Manufacturing for Exploration - Library

Manufacturing for Exploration

Final Report

International Space University

MSS Program 2019

This MSS 2019 Team Project work was conducted at the ISU Strasbourg Central Campus in Illkirch-

Graffenstaden, France

© International Space University. All Rights Reserved

The front cover is an original piece created by Lord Jim Tuohy. It is titled

‘Manufacturing for Exploration’. Inspired by the ideas put forward in the

report, it encompasses the idea that in-space manufacturing is creating

a path to enable human deep space exploration.

The Executive Summary and the Final report may be found on the ISU web site at

http://www.isunet.edu in the “ISU Team Projects/Student Reports” section. Paper copies of the

Executive Summary and the Final Report may also be requested, while supplies last, from:

International Space University

Strasbourg Central Campus

Attention: Publications/Library

Parc d’Innovation

1 rue Jean-Dominique Cassini

67400 Illkirch-Graffenstaden

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Publications:

Tel +33 (0)3 88 65 54 32

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e-mail: [email protected]

Acknowledgments

The Manufacturing for Exploration team would like to thank our Faculty Interface Prof. Vasilis Zervos, for

expanding our vision for the report.

The team would also like to expresses its gratitude to the faculty, Prof. Chris Welch, Prof. Volker Damann,

Prof. Taiwo Tejumola, Prof. Hugh Hill, Ms. Danijela Stupar, Prof. Gongling Sun and Dr. Omar Hatamleh,

and teaching assistants in ISU Ms. Ana Garduño Baltazar, Mr. Hameed Mohamed, and Mr. James Hurrell,

who with their valuable suggestions, guidance, and feedback, helped us immensely to produce the final

report.

Special thanks to ISU Librarian Ms. Muriel Riester, ISU IT staff, Mr. Nicolas Moncussi and Mr. Joel Herman,

ISU Administration, Ms. Claire Byrski and Ms. Christine Jenck, for granting us access to all the ISU facilities

and services.

We would especially like to thank Abeba Birhane from University College Dublin, James Baltitude from

OrbitFab, Xavier Fruh from BeAM Machines, Stefan Siarov from Valispace, Pasi Vainikka and Juha-Pekka

Pitkänen from Solar Foods Ltd., and Lord Jim Tuohy for sharing their invaluable experiences and opinions

with us. Their contribution and assistance were of great value to the project.

Faculty Interface Dr. Vasilis Zervos

Dr. Taiwo Tejumola

Teaching Associate James Hurrell

Authors

Marc Abi-Fadel Mazin Al Harbi

Miguel Chafen Tongtong Chen

Alexandria Farias Sarah Halpin

Zhuhui Jiang Sara Khan

Jue Liu Matthew McGrath

Adam Nawal Kuren Patel

Adi Rahamimoff Stephanie Rocha

Ignaty Romanov-Chernigovsky Daniel Rotko

Eóin Tuohy Héloïse Vertadier

Hannah Woodward

Faculty Preface

On Behalf of the ISU Faculty:

Innovation and technological change are intrinsically linked with the space sector, which though faced by definitional challenges, is nonetheless typically perceived entailing space components manufactured on Earth. Emerging technologies and developments in various fields lead to expanding the concept of space sector and industry, by emerging in-space manufacturing and 3D printing applications. The state of the art and applications feasibility of such concepts in the near and distant future is a task requiring research and synthesis within an interdisciplinary intercultural and international environment, fitting to the nature of ISU. Thus, a group of approximately twenty ISU Masters students in 2018/2019 embarked into the unknown in an effort to expand frontiers and exploit the options for a truly ‘’space-based’’ industry. As is often the case, the hard work and struggle associated with expanding frontiers is rarely felt by the authors into an environment where a perfect idea is the enemy of a good one. For them, the critical mass of research-amazed knowledge is the perfect complement to a report that provides an invaluable insight for the space sector and community. The report and auxiliaries provide a comprehensive approach to the outer space manufacturing challenges with existing and future applications and demands. Starting from the ISS and moving into future exploration scenarios supporting distant missions seems by now quite familiar with the authors who have covered significant distance in a short time. As for the faculty, we are grateful, for there is little more than positive experiences and knowledge obtained from our interactions with the group. We wish them the best, along with this and future works that will confidently challenge and add value to the space and wider society.

Professor Vasilis Zervos

Team Preface In 2018 our group was formed to examine and explore the topic of, in-space manufacturing. Our team was composed of nineteen Masters students at the International Space University (ISU). In keeping with ISU’s 3Is program aims (Intercultural, Interdisciplinary and International work) we came from fourteen different academic backgrounds and fifteen different nationalities. Our goal was to create a team capable of meeting deliverable goals of communicating our findings on the topic in hand.

We discovered quickly that in-space manufacturing is a far reaching subject, an excellent example of a topic requiring a multidisciplinary approach. After spending time learning more about our new teammates strengths and skills, we voted on the creation of a team structure thus developing our management team consisting of our Project Manager, Faculty Interface and Chief Editor to support our efforts. Other team members’ roles remained fluid to meet the needs of the work. The output from our research is indebted to the dynamic and dedicated work of our team. Through the last six months we have learnt from each other and grown in the skills critical to the successful completion of this work.

No man or woman is an island, this is particularly true when attempting to develop a critical mass of knowledge on a previously unknown topic. When spending six months exploring such a vast topic it is easy to come to crossroads, dead ends and roundabouts. We remain immensely grateful to all who kindly offered their time and expertise to allow us to find our way through.

Humanity appears to be looking to the skies again, dreaming of space exploration and innovated techniques. Terrestrial based 3D printing and manufacturing techniques continue to show huge potential to be of significant use in enhancing humanity’s quality of life. Now is the time to utilize that potential to enhance humanities dreams.

Abstract

Humanity’s ambitious dreams of leaving footprints on far away worlds comes many challenges.

Fortunately, with the advances in current technology, these challenges can be conquered from many

directions. In-space manufacturing (ISM) has the potential to be one of the technologies which will bring

human exploration dreams to life. ISM includes techniques such as 3D printing, recycling, and assembling,

chemical and biological process. Due to its many benefits, such as minimal wastage and highly

customizable products, a significant focus will be drawn to 3D printing in this report. This technology has

proven itself to be fruitful to a variety of Earth applications. Hence, current initiatives are focusing on

expanding 3D printing into space, more specifically to space habitats.

This report discusses on the potential of ISM as a solution to enable a self-sustaining space habitat without

re-supply requirements. The report is split into two sections. The first section of the report uses the

International Space Station (ISS) as an analogue to identify numerous areas where ISM can be and is

leveraged during expeditions.

In the second section, a crewed deep space mission is defined as a space habitat with seven crew members

beyond the Earth’s GEO ring for a continuous period of three years without re-supply. Since the location

and duration of this mission are dissimilar to the ISS, differences in technical and crew requirements of

the two space habitats are established. ISM technologies, either developed or in-development, are

proposed for each of the requirements. The respective technology readiness level, challenges and risks

are also mapped for each proposed technology. Furthermore, the mission is perceived through a financial,

political, legal, and ethical lens.

Following the two sections, the report concludes with the added value of ISM and recommendations to

any gaps identified between space habitat requirements and technology capabilities.

297 / 300 Words

Table of Contents INTRODUCTION 1

Motivation 2

Methodology 4

ISS ANALOG 5

1 Internal Failures and External Threats 6

1.1 Internal Failure 6

1.2 External Threats 8

1.2.1 Impact from External Objects 8

1.2.2 Extreme Temperatures 10

1.2.3 Radiation 10

2 Crew Needs 11

2.1 Atmosphere 11

2.2 Water 12

2.3 Food 12

2.4 Crew Health 15

2.5 Clothing 16

3 Additive Manufacturing on ISS 17

3.1 Current Techniques 17

3.2 In-Development Techniques 21

4 Other Manufacturing on ISS 24

Chapter 1 Summary 27

DEEP SPACE CREWED MISSION 28

1 Mission Type 29

2 Human Factors 31

2.1 Critical Crew Needs 32

2.1.1 Requirements 32

2.1.2 Technology 33

2.2 Waste Management 35


2.2.2 Technology 35

2.3 Medicine 37


2.3.2 Technology 38

2.4 Medical devices 41


2.4.2 Technology 41

2.5 Mental Health 45


2.5.2 Technology 46

2.6 Radiation (Crew) 48


2.6.2 Technology 50

3 Technical Factors 54

3.1 Radiation 54


3.1.2 Technology 55

3.2 Communication 56


3.2.2 Technology 59

4 Spacecraft Parameters 61

4.1 Storage Space 61

4.2 Mass 61

5 TRL Timeline 63

6 Challenges 66

6.1 Design Challenges 66

6.2 Manufacturing Challenges 68

6.3 Qualification and Standardization Challenges 70

7 Risks 72

8 Financial Considerations 79

8.1 Case Study - Plastic Spares 80

9 Political Considerations 84

9.1 Public Private Partnerships 84

9.2 Agencies Grading 84

9.2.1 Big Partners 84

9.2.2 Future Players 87

9.2.3 Recommendations 88

10 Legal Implications 90

10.1 Legal framework 90

10.2 General considerations 90

10.3 Intellectual and Industrial property issues 90

10.3.1 Intellectual property 90

10.3.2 Industrial property law 90

10.3 Goods or services provider? 91

10.3.1 The difference between the two notions 91

10.3.2 Manufacturing in orbit only implies providing goods 91

10.4 3D printing and liability: Tort law 91

10.4.1 Tort law 91

10.4.2 For the crewed mission: Health issues and Tort Law 93

11 Ethics 94

11.1 Ethics and Automation 94

11.2 Mimicking Mother Nature 95

ADDED VALUE 96

RECOMMENDATIONS 98

CONCLUSION 101

REFERENCES 103

I

List of Figures

Figure 1: Manufacturing methods which are considered as subcategories of ISM in this report. 18

Figure 2: Classification of additive manufacturing techniques 19

Figure 3: Percentage of failed parts and components on the ISS 24

FIgure 4: Estimated ISS maintenance logistics, 2012-2020. Mass estimates are for spare items only 25

Figure 5: Illustration of the damage caused by a hypervelocity impact 26

Figure 6: Sentinel-1 fragment impact in space 26

Figure 7: Multi-layer and twin-layer Whipple shields with debris impacts 27

Figure 8: University of Stuttgart algae bioreactor 31

Figure 9: A customized finger splint 3D printed on the ISS 34

Figure 10: The 3DP Tech Demo; the first 3D Printer in zero gravity 35

Figure 11: A sample of 3D printed parts on the ISS for the astronauts 36

Figure 12: The Additive Manufacturing Facility (AMF) on board of the ISS 38

Figure 13: The Refabricator 39

Figure 14: Shuttle Remote Manipulator System and Mobile Servicing Systems 42

Figure 15: European Robotic Arm 42

Figure 16: Japanese Experimental Module Remote Manipulator System 43

Figure 17: Robonaut 2 onboard ISS with astronaut Steven Swanson 44

Figure 18: Diagram of current ISS and required future habitation systems elements 49

Figure 19: FabRx’s chewable medicines showing different dose sizes 58

Figure 20: Surgical tools, splint, face mask, otoscope and a fitting 60

Figure 21: Examples of patient specific 3D printed consumables 61

Figure 22: Heart model by Stratasys 62

Figure 23: 3D printed hip joint replacement tool by GE 63

Figure 24: Metal 3D printed automatic suturing tool from Suture 63

Figure 25: Effectiveness of different radiation protection materials vs. launch mass 69

Figure 26: Simple hydrogen shielding design 70

Figure 27: Solar Cell Power Loss vs Radiation (700 km altitude, 30° inclination) 73

Figure 28: NASA Deep Space Network Capabilities 76

Figure 29: Relationship between Performance and Antenna Size 76

Figure 30: Archinaut Dilo Spacecraft Attaching its Reflectors 78

Figure 31: Mass savings from AM using earth based and ISRU feedstock 79

Figure 32: An explanation of TRL levels 82

Figure 33: Risk matrix associated with proposed ISM technologies 97

Figure 34: NASA’s forecasted available budget and costs of human spaceflight program 102

Figure 35: NASA Design Review Architecture 5.0 for Human Landing on Mars 103

II

List of Tables

Table 1: List of Phase I products 34

Table 2: List of Phase II products 37

Table 3: Printing capacity of the AMF 38

Table 4: Examples of AMF products printed on the ISS 38

Table 5: Systems in Phase I and II of NASA’s ISM technology development efforts 40

Table 6: Closed loop efficiencies for Oxygen, Food and Water for a 3-year mission of 7 members 50

Table 7: Mass savings with increased recycling rates 50

Table 8: A bioregenerative HPGF’s impact on S/C food production and atmospheric recycling 51

Table 9: Breakdown of ISS waste for three people per year 53

Table 10: Comparison of aerobic and anaerobic waste treatment 54

Table 11: Examples of pharmaceutical formulations that were developed by 3DP technology 56

Table 12: Printing technologies for medical devices 60

Table 13: Career astronaut limits for males and females at varying age 67

Table 14: Mission specific radiation doses 67

Table 15: Trade-off to provide advantages and disadvantages of various shielding methods 70

Table 16: Recommendations for radiation shielding in spacecraft 71

Table 17: Free-Space Path Loss at Various Frequencies 75

Table 18: Mass of spares and reduction by using AM on a twenty-six month deep space mission 79

Table 19: Technology Readiness Levels of discussed ISM technologies 83

Table 20: SWOT analysis of 3D printing 84

Table 21: ISM Design Challenges 85

Table 22: ISM Manufacturing Challenges 87

Table 23: ISM Qualification and Standardization Challenges 89

Table 24: Risks, Ratings, and Mitigation strategies 90

Table 25: Information regarding ISS Spares 100

Table 26: Mass and Costs of Plastic Spares Required on a Spacecraft without ISM Capabilities 100

Table 27: Mass and Costs of Plastic Spares Required on a Spacecraft with ISM Capabilities 100

Table 28: Mass and Costs of Plastic ISM Equipment Required on a Spacecraft 101

Table 29: Recommendations for working with agencies 106

III

List of Acronyms

3DP 3D Printing

ABS Acrylonitrile butadiene styrene

AI Artificial Intelligence

ALSS Adaptive Laser Sintering System

AM Additive Manufacturing

AMF Additive Manufacturing Facility

AMSC Additive Manufacturing Standardization Collaborative

ANSI American National Standards Institute

ASA Acrylic Styrene Acrylonitrile / Aminosaicylic Acid

BEAM Bigelow Expandable Activity Module

BLEO Beyond Low Earth Orbit

BPS Biomass Production System

CAD Computer-Aided Design

CAS Chinese Academy of Sciences

CCPA Central Committee of the Communist Party of China

CMSE China Manned Space Program

CNSA Chinese National Space Agency

COPUOS United Nations Committee on the Peaceful Uses of Outer Space

CQ Crew Quarters

CRG Cornerstone Research Group

CRISSP Customizable Recyclable International Space Station Packaging

CSA Canadian Space Agency

CSU Center for Space Utilization

DLP Direct-Light Processing / Digital Light Processing

DSOC Deep Space Optical Communications

DMLM Direct Metal Laser Melting

DRA Design Reference Architecture

EBF3 Electron Beam Freeform Fabrication

EBM Electron Beam Melting

ECEEE European Council for an Energy-Efficient Economy

ECLS Environmental Control and Life Support System

EEC European Economic Community

EEG Electroencephalogram

EF Exposed Facility

EMCS European Modular Cultivation System

ERA European Robotic Arm

ERASMUS European community Action Scheme for the Mobility of University Students

ESA European Space Agency

ESPRIT European System Providing Refueling, Infrastructure and Telecommunications

IV

EU European Union

EVA Extra-Vehicular Activity

EXPRESS Expedite the PRocessing of Experiments to Space Station

FabLab Fabrication Laboratory

FDM Fused Deposition Modeling

FDA Food and Drug Administration

FFF Fused Filament Fabrications

FIT Factory in a Tool

FSPL Free-Space Path Loss

GCR Galactic Cosmic Radiation

GE General Electric

GEO Geosynchronous Equatorial Orbit

HDPE High-Density Polyethylene

HEOMD Human Exploration Operations Mission Directorate

HERA Hybrid Electronic Radiation Assessor

HMC Heat-Melt Compactor

HPGF Hydroponic Plant Growth Facility

ISM In-Space Manufacturing

ISRO Indian Space Research Organization

ISS International Space Station

ISU International Space University

IVA Intra-Vehicular Activity

IVTEPC Intra-Vehicular Tissue Equivalent Proportional Counter

JAXA Japanese Aerospace Exploration Agency

JEMRMS Japanese Experimental Module Remote Manipulator System

LaRC Langley Research Center

LED Light-Emitting Diode

LEO Low-Earth Orbit

LH2 Liquid Hydrogen

LMD Fused Metal Deposition

LOX Liquid Oxygen

MAMBA Metal Advanced Manufacturing Bot-Assisted Assembly

MBS Mobile Base System

MLI Multi-Layer Insulation

MLM Multi-purpose Laboratory Module

MPCV Multi-Purpose Crew Vehicle

MPLM Multi-Purpose Logistics Module

MR Manufacturing Readiness Level

MSS Mobile Servicing System

NASA National Aeronautics and Space Administration

NextSTEP Next Space Technologies for Exploration Partnerships

OGS Original Groove System

V

PA Polyamide

PC Polycarbonate

PEI Polyetherimide

PEU Plant Experiment Unit

PGBA Plant Generic Bioprocessing Apparatus

PGF Plant Growth Facility

PGU Plant Growth Unit

PPP Public-Private Partnership

PPSF Polyphenylsulfone

R2 Robonaut 2

R&D Research and Development

REM Radiation Enclosure Monitor

RFID Radio-Frequency Identification

SATCOM Satellite Communications

SBIR Small Business Innovative Research

S/C Spacecraft

SIMPLE Sintered Inductive Metal Printer with Laser Exposure

SLA Stereolithography

SLM Selective Laser Melting

SLS Selective Laser Sintering

SPDM Special Purpose Dexterous Manipulator

SPHERES Synchronized Position Hold Engage Reorient Experimental Satellites

SRMS Shuttle Remote Manipulator System

SSA Space Situational Awareness

SEE Single Event Effect

SMM Satellite Manufacturing Machine

SpaceX Space Exploration Technologies

SSRMS Space Station Remote Manipulator System

STEPS Software and Tools for Electronics Printing in Space

STTR Small Business Technology Transfer

SWOT Strengths Weaknesses, Opportunities, Strengths

TEPC Tissue Equivalent Proportional Counter

TRL Technology Readiness Level

TUI Tethers Unlimited

UAM Ultrasonic Additive Manufacturing

UM Nodal Module

UNOOSA United Nations Office for Outer Space Affairs

US United States

VEGGIE Vegetable Production System

Introduction

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INTRODUCTION

Space has always been seen as a domain of exploration and discovery. The mystery and unknown quality

of space has led to speculations and tales of fantasy. Coupled with an infinite and elusive nature, religions

and mythologies have looked to the heavens for their inspiration for thousands of years. From launching

the first object into orbit in 1957 to a human-made object reaching over 145 astronomical units away

from Earth, humans have always been intrigued by the curiosities of space and have fed their curious

minds through technology. Technology provides the capability of expanding upon humanity’s current

accomplishments in the space industry. Specifically, implementing manufacturing techniques (a process

which outputs a product from an input) in-space has the potential to revolutionize the way humans use

and explore the barriers of space.

The following report will closely follow the definitions established by Skomorohov, Hein, and Welch (2016)

and Trujillo, et al. (2017) when defining in-space manufacturing (ISM). Skomorohov, Hein, and Welch

(2016), define ISM as “any endeavor which takes place outside of Earth’s atmosphere and which performs

any of the three activities: fabrication, assembly, and integration”. Trujillo, et al. (2017) define ISM as “an

umbrella term for a variety of technologies, processes and architectures which deliver a desired component

or system to a spacecraft outside of the traditional Earth-launch paradigm”.

Therefore, this report will consider the ISM subcategories as illustrated in Figure 1. However, 3D printing,

also known as additive manufacturing (AM), will constitute the major focus of the report due to the recent

rise in interest of 3D printing in-space. Furthermore, recycling, assembly, biological, and chemical

manufacturing processes will be addressed in the report.

Figure 1: Manufacturing methods which are considered as subcategories of ISM in this report.

Introduction

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Current initiatives have been focused on developing traditional manufacturing by pushing it towards in-

space 3D printing. Common 3D printing techniques begin with the production of a Computer Aided Design

(CAD) model or part. Afterwards, the 3D printer reads in data from the CAD file and lays down or adds

successive layers of liquid, powder, sheet material or other material, in a layer-upon-layer fashion to

fabricate a 3D object (AmazingAM, 2018).

These techniques are expected to play a significant role in the future of manufacturing due to the

numerous benefits as listed by Ghosh (2015): highly customizable, minimal wastage of raw materials,

lighter, and more optimized parts. Researchers are looking into enhancing current printing technologies

and expanding its borders. Terrestrial applications of 3D printing have been very successful and there is a

new focus to reap the benefits this technology in space. Figure 2 describes the current additive

manufacturing techniques available on Earth. Most of the techniques listed in Figure 2 cannot yet be

implemented in space due to a microgravity environment. However, researchers are currently focusing

on ways to tackle this challenge.

Figure 2: Classification of additive manufacturing techniques (Joshi and Sheikh, 2015).

Motivation

Although there are many reasons to pursue ISM, the main rationales are outlined by Johnston, et al.

(2014):

Rationale 1 - Known and Predicted Repair

The normal wear and tear of parts on the ISS require stockpiles of spares and additional components to

be readily available for timely replacement. These stockpiles can occupy large volumes on the ISS which

can be vacated for other needs such as crew recreational quarters. These large storage volumes will be

reduced with the introduction of additive manufacturing. Any required component can be printed and

Introduction

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there will be no need to store components which may or may not be used; instead compact filament,

powder or liquid for the printers will be stored.

Rationale 2 - Known Production and Assembly

Current launching techniques generate intense vibrations which can be detrimental to delicate cargo.

There are also structural and geometric constraints imposed on payloads due to the limited space. These

issues can be by-passed through manufacturing of delicate or large components in space. Furthermore,

printing techniques on the ISS will mitigate the significant cost of launching all equipment possibly

required to the ISS as astronauts on the space station have long been reliant on launches from Earth to

bring spare parts.

Rationale 3 - Unknown Repair and Replacement

Due to parts and components failing spontaneously, either the stockpiles of common failing parts are used

or the crew has to wait for a resupply mission. In the case of waiting for a resupply mission, the disturbance

to flight experiments, crucial operational equipment failure, or even a medical emergency can be

detrimental to the success of a mission. Such critical situations can be prevented by the 3D printing

techniques available on a space habitat for quick responses to any unforeseen circumstances.

Parts that are unlikely to fail, but do, may not have replacements stored. The ability to produce unique

parts on demand enables these unforeseeable failures to be easily resolved. With 3D printing these

replacement parts can be produced on station, thus removing the need for storage of spare components

with a low risk of failure.

In the near future, ISM may become the primary platform for producing numerous goods as these

methods may be more economical and efficient. As stated by Jason Crusan, director of NASA's Advanced

Exploration Systems Division at NASA Headquarters in Washington, "Additive manufacturing with 3D

printers will allow space crews to be less reliant on supply missions from Earth and lead to sustainable,

self-reliant exploration missions where resupply is difficult and costly. The space station provides the

optimal place to perfect this technology in microgravity" (Hubscher and Mohon, 2014). Furthermore, ISM

has the potential to positively affect human spaceflight operations by reducing existing logistics

requirements for the ISS and future long-duration human space missions.

This report will serve to provide knowledge in regards to the possibility of exploiting ISM to bring the

dreams of deep space crewed exploration to life. The role which current technology can play to support

ISM and subsequently enable crewed deep space exploration will be discussed in detail. This transfer of

knowledge from the authors to the readers will be accomplished through a structured approach.

Introduction

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Methodology

Prior to this report, an extensive literature review was performed to understand the current terrestrial 3D

printing technologies and their potential applications in the space sector. ISM techniques currently in

development and utilized on the ISS have also been reviewed and analyzed to provide insight into the

potential of expanding these techniques to deep space crewed missions. For the purpose of this report,

the term deep space applies to any distance beyond the geosynchronous equatorial orbit (GEO).

As of now, many additive manufacturing projects have been carried out successfully on the ISS. Although

these products are currently on a small scale, they are a stepping stone towards printing larger and more

complex structures in space. Along with this first step come many questions about the potential of 3D

printing in space and what breakthroughs these technologies will bring into fruition. Additionally, other

ISM technologies such as assembly, recycling, biological and chemical processes have enabled the ISS to

come into existence and sustain a crew of six crew members at a time. Hence, this report has been divided

into two chapters to assess the potential of ISM within space habitats: 1) ISS Analogue and 2) Deep Space

Crewed Mission.

Chapter one of the report provides a foundation for further study, exploring the current state and

projected development of ISM aboard the ISS. By analyzing common equipment failures on the ISS along

with the associated risks, the role of 3D printing in mitigating those risks is assessed. Furthermore,

analyzing additional requirements for the ISS due to human presence can open new horizons for the

potential of 3D printing. Therefore, it is important to discuss current technologies, developing

technologies and other manufacturing methods to be deployed in space and on the ISS.

The second chapter of the report builds onto the foundation presented in the first chapter and expands

ISM to crewed missions in deep space. The mission type and the respective requirements are defined and

initial assumptions are established to provide consistency and ease of utilizing the ISS as a reference.

Afterwards, the difference in requirements between the ISS and the deep space mission are outlined.

These requirements are classified into: (i) human factors and (ii) technical factors. Manufacturing

technologies, specifically 3D printing, which are currently developed or in-development for Earth or space

application are proposed as potential solutions for each of the aforementioned requirements. The

feasibility analysis of the proposed technologies will entail: (i) technology readiness level (TRL), (ii) risks,

and (iii) challenges. Once the technical aspects of the missions are defined and discussed, the mission will

be analyzed from a political, legal, ethical, and financial perspective. This perspective will shed light onto

any additional challenges with using ISM to enable a crewed deep space mission.

After the two aforementioned chapters, the report will examine the added value of utilizing ISM. Lastly,

recommendations in regards to filling any gaps between crewed mission requirements and the current

technology will be discussed.

CHAPTER ONE

ISS ANALOG

Chapter One: ISS Analogue

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1 Internal Failures and External Threats

Like any system, the ISS is prone to failures. These failures can stem from hardware failures of individual

components or within subsystems. The crew on the ISS is responsible for performing duties related to

replacing and repairing damaged components. In addition to internal failures, there are also external

threats originating from the harsh environment of space. These external threats can impact the normal

operations of the station. With advances in ISM techniques, the logistical burden of replacing or repairing

components can be reduced while the external threats are mitigated.

1.1 Internal Failure

The ISS witnesses numerous failures in hardware across different components as illustrated in Figure 3.

Those failures can stem from components that have reached their end-of-life due to wear and tear or

unexpected failures. Components with a limited lifetime need to be replaced and repaired on a daily basis,

namely igniter tips, overhead lights, and various waste filters in the regenerative life support system.

Some components may be utilized on a daily basis or some may be delicate which makes them more

prone to failure than others. The most common failures ordered by highest to lowest failure rate are: (i)

electrical and electronic components, (ii) plastic and composites, (iii) mechanical metal parts, and (iv)

ceramics and glass. Unfortunately, with current technology, approximately 18% of hardware failures are

not candidates for additive manufacturing or repair (National Research Council, 2014a).

In addition to damage and failure, the ISS crew must contend with lost or misplaced tools and unattached

components due to the ventilation system and other microforces. Therefore, there is a need for multiple

spare components to replace lost or damaged tools. 3D printing can help reduce the demand for spare

components by introducing on-demand production of tools and parts. Current 3D printing technologies

on the ISS and their catalog of products are further discussed later in this chapter in Sections 3.1, 3.2, and

4.

Figure 3: Percentage of failed parts and components on the ISS (Adapted from the National Research

Council, 2014a).


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Currently, the ISS relies upon a resupply mission every three months which carries crucial cargo. In each

resupply, the cargo encompasses various substances ranging from sustenance for crew members to

replacement parts and spares for equipment susceptible to failure (Owens and de Weck, 2016). The mass

of resupply that the ISS requires is displayed in Figure 4. As shown, there are 13,170 kg of spares stored

on the ISS for the estimated failure mass of 450 kg annually. Unfortunately, nearly 95% of the 31,170 kg

of spares are never utilized, thus requiring an unnecessary high financial investment to respond to

maintenance demands (Owens and de Weck, 2016). Furthermore, the volume and mass detained for

storage uses can be drastically reduced with ISM. Raw material required for 3D printing is commonly

stored in compact geometries, which can help save volume. The need to store an abundant amount of

spares will be nonessential since a component can be printed when it is required. Hence, the endurance

of ISS, time without resupply, will be increased with the introduction of ISM.

FIgure 4: Estimated ISS maintenance logistics for 2012-2020, including ground storage, upmass, on-orbit

storage, and expected utilization. Mass estimates are for mass of spare items only; does not include

packaging and carrier mass (Owens and de Weck, 2016).


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1.2 External Threats

The orbital altitude of the ISS lies in a harsh environment of vacuum, microgravity, extremes of

temperature, meteoroids, space debris, ionospheric plasma, and ultraviolet and ionizing radiation (Thirsk,

et al., 2009). Given the environment that the ISS operates in, an assessment of environmental threats and

mitigation strategies is necessary. The failures and dangers associated with impact from external objects,

thermal control, and radiation will be discussed with respect to the potential of ISM in these areas.

1.2.1 Impact from External Objects

According to ESA, there are more than 29,000 objects larger than 10 cm that can heavily damage a

spacecraft. The impact of a 1 kg piece of debris has the same impact as a 35,000 kg tractor-trailer travelling

at 190 km/hr (Thirsk, et al., 2009). Figure 5 displays a 12 mm aluminum sphere travelling at a velocity of

6.8 km/s into an aluminum block. This illustrates the extent of an impact from a hypervelocity space

object, either a small meteoroid or debris, on the ISS and more generally on a spacecraft. Any collision of

a 10 cm object with a spacecraft will most likely cause a catastrophic failure (ESA, 2013). Apart from

physical damage to the ISS’s hull, damage to solar panels can occur, leading to power outages. A collision

between a piece of fragment debris and Sentinel-1 solar panels is shown in Figure 6.

Figure 5: Illustration of the damage caused by a hypervelocity impact (ESA, 2013).

Figure 6: Sentinel-1 fragment impact in space (ESA, 2013).


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The probability of a meteoroid or micrometeoroid impact with the ISS has increased when compared to

the probability during the beginning of ISS operations (Akahoshia, et al., 2008). NASA has estimated the

probability of a micrometeoroid debris strike causing depressurization of the station, fire, or toxic release

of ammonia is 1 in 120, 1 in 46,000, and 1 in 5.6 million, respectively. In addition, the risk of a

micrometeoroid penetrating the station and causing a catastrophic failure (a condition where disabling or

fatal injury occurs to personnel or loss of the ISS occurs) is 33 percent and 6 percent, respectively (NASA

Inspector General, 2018). Therefore, Space Situational Awareness (SSA) detects and monitors space

objects, including debris, in Earth’s orbit and determines their position and velocity (Elias, et al., 2014).

Currently, the hazard of potential debris collisions with the ISS is minimized by: (i) shielding critical

elements of the ISS to protect them from impacts with the meteoroids and debris (<10 cm), (ii) performing

collision avoidance maneuvers for debris larger than 10 cm, and (iii) implementing design features and

operational procedures (National Research Council, 1997).

Current shielding techniques use outer shell aluminum and Whipple shields as illustrated in Figure 7.

Whipple shields usually include layers of Kevlar or Nextel which utilize their high strengths to break the

projectile into smaller and lower energy particles (Christiansen, et al., 1995). It is possible to replace the

damaged shields. By utilizing ISM, the replacement shields may be 3D printed in space to avoid launching

constraints imposed on cargo payloads. Furthermore, shielding plates that have been exposed to high

impact frequencies can be removed and recycled (Section 3.2 of Chapter 1 further describes metal

recycling capabilities on the ISS using MAMBA from Tethers Unlimited). Thereon, the recycled material

can then be utilized as raw material for the production of replacement shields. This process is currently

being utilized terrestrially; Kevlar is being recycled by companies such as Ballistic Recycling Intl (Anon,

2019). However, such a recycling technology has yet to be developed for the ISS and increase ISM

capabilities. Nevertheless, the assembly of Whipple shields on the exterior of the ISS will require robotic

assembly arms which are discussed in further detail in Section 4 of this chapter.

Figure 7: Multi-layer and twin-layer Whipple shields with debris impacts (NASA, 2013).


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1.2.2 Extreme Temperatures

The ISS is on the sunlit side of the Earth for 45 continuous minutes which exposes it to temperatures in

excess of 100°C. While in Earth’s shadow for an equivalent time, the ISS can experience temperatures

below -100°C (Thirsk, et al., 2009). To protect the crew and system components, four methods are used

to control the thermal system: insulation, surface coatings, heaters, and heat pipes (NASA, 2015a).

Without proper thermal control, various ISS systems can fail due to environmental factors such as extreme

cooling and heating.

Thermal threats can be further mitigated through the use of ISM. During emergency situations, such as

damage to thermal systems, extra insulation may be 3D printed to maintain a temperature which allows

subsystems to operate at full efficiency and effectiveness. In addition, heat pipes and heat exchangers are

currently 3D printed on Earth using laser powder bed fusion (Saunders, 2018). Such a technology can be

leveraged in space for emergency situations when excess thermal energy needs to be disposed of.

Furthermore, spare components can also be printed from recycled parts for heaters and heat pipes if

there is damage to the current components.

1.2.3 Radiation

The ISS orbits above the Earth’s atmosphere exposing it to radiation sources from galactic cosmic rays

(energetic particles from outside the solar system), particles trapped in the Earth’s magnetic field (the Van

Allen Belts), and solar energetic particle events (solar flares) (Thirsk, et al., 2009). Both ionizing and non-

ionizing radiation can cause long-term health effects, equipment failures, and malfunctions. Galactic

cosmic rays are high-energy and almost impossible to fully shield against, however, water shelters and

polyethylene are currently used as radiation shields for spaceflight and orbital habitats. In addition, a

deployable structure to protect the ISS from radiation shielding is possible but due to the size and mass

constraints posed by some launching capabilities, these large and heavy structures are impractical

(International Space University Space Studies Program, 1998). Hence, by 3D printing these deployable

structures in space, these launch constraints can be bypassed.


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2 Crew Needs

Due to the lack of autonomy on the ISS, there is a need for a continuous human presence. In order to

ensure the health, safety, and welfare of the crew in the hostile environment of space, the space station

must be equipped with numerous life support systems. Since each ISS expedition lasts a duration of

approximately six months with three to six crew members, there is a need for a habitable atmosphere; a

supply of water, food, and clothing; and safety considerations for the crew. The following section will

further discuss these requirements in detail along with their respective ISM techniques (recycling,

chemical process, and/or biological process).

2.1 Atmosphere

The oxygen requirements of an astronaut on the ISS is 0.83 kg per day (303 kg per year) (NASA, 2015c).

The requirement is predominantly supplied by electrolysis. This chemical process utilizes electricity from

the solar panels to split water into hydrogen and oxygen molecules. Thereafter, the hydrogen molecules

are vented into space. Excess hydrogen molecules can be used as a source of fuel or propellant in the

future. This could be an efficient way to use all products and recycle. However, large quantities of stored

hydrogen around the station do expose humans to the potential risk of an explosion (Barry, 2000).

In addition to oxygen requirements, the atmosphere within the ISS must be free of gases in concentrations

which pose a danger to crew health. Humans produce gases such as ammonia, carbon monoxide and

methane via urine, respiration, and digestion, respectively. These gases are harmful in significant

concentrations and hence they are filtered from the ISS air via charcoal filters. Furthermore, since October

2010 the ISS features a Sabatier process, which allows carbon dioxide to catalytically react with hydrogen

to create drinkable water and methane (NASA, 2011). Any excess carbon dioxide from the process,

exhaled by humans, is vented into space. In addition, two backup responses to oxygen demands are

implemented on the ISS: (i) large tanks of compressed air are mounted outside of the airlock capsule, and

(ii) storage of metal canisters packed with perchlorate, which release oxygen when they are burnt (Barry,

2000).

Although the current technique to maintain the atmosphere within the ISS is through a chemical recycling

process, several technological upgrades are required to fully close the loop. The current systems on the

ISS have a 42 percent oxygen recovery rate which is not satisfactory (NASA Inspector General, 2018).

Hence, due to the low efficiency, resupply missions of oxygen are required to fill the gap in oxygen

production. By improving the chemical recycling process, a higher recovery rate of oxygen can eliminate

resupply requirements. Furthermore, some components of the environmental control and life support

system have an average lifetime of less than six months (NASA Inspector General, 2018). Therefore,

subsystems critical to the crew are dependent on storage of spares or resupply missions. An error in

calculations or spontaneous failure of a component can be life threatening since a resupply mission only

occurs every three months. Fortunately, these risks can be minimized with the introduction of 3D printing

onboard allowing a crucial component to be produced instantaneously.


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2.2 Water

In order to create a habitable environment for the astronauts on the ISS, abundant amounts of water

must be accessible. Water is required for both metabolic and hygienic purposes. On the ISS, an astronaut

requires 2.59 kg and 25.27 kg of water daily for consumption and hygiene, respectively. These values

equate to a requirement of approximately 10,790 kg of water per year, per astronaut, to sustain day-to-

day operations (Jones, 2010).

The current method of producing water on the ISS is through recycling from atmospheric conditions,

waste water, H2-O2 fuel cells, CO2 reduction, and condensation from equipment. The waste water which

is collected has to be filtered prior to usage. The waste water passes through three steps before it is

purified: (i) a filter which removes particles and debris, (ii) a multi-filtration beds which remove organic

and inorganic impurities, and (iii) a catalytic oxidation reactor which removes volatile organic compounds

and eliminates bacteria and viruses (Barry and Phillips, 2000). In addition, water purification can be also

be achieved by bio-regenerative systems like plants. Plants have the ability to purify waste or partially

processed water by utilizing the nutrients in the waste water and perspiring water vapor into the

atmosphere (Lane and Schoeller, 2000). This topic will be expanded upon in Sections 2.1 and 2.2 of

Chapter 2.

The current production system runs at 90 percent efficiency which leads to the loss of approximately three

to six tonnes of water per year that needs to be resupplied (Jones, 2010). It is important to note this figure

is highly dependent on crew size hence the large variability. The water is lost from, but not limited to,

production of unusable brine, consumption from generating oxygen, leaks in the airlocks, and leaching by

CO2 removal systems (Barry and Phillips, 2000). It is important to increase the efficiency of ISM of water

on the ISS and close the loop. Subsequently, the resupply requirements will be reduced and the endurance

of the ISS will be increased.

2.3 Food

The prior sections discussed two out of the three essential needs for humans to sustain life. This section

is going to focus on the third essential need, food. According to NASA, the food requirement for an

astronaut on the ISS is 2 kg per day (NASA, 2007). Over a period of one year, considering a crew size of

six, this requirement measures to 4,380 kg. Currently, this mass of food is being fulfilled solely by resupply

missions.

As previously defined in the introduction, ISM encompasses biological processes such as in-space food

production. This process currently at the experimental stage. Stutte, et al. (2011) identified two important

objectives that must be achieved by any in-space food production system: (i) support growth from start

to finish and (ii) retain water, media, and biological material without contaminating the spacecraft.

Furthermore, several food products have been identified as candidates for production in microgravity:

agricultural products, microbiological products, chemical synthesis products, animal products, and waste

recycling products (Eckart, 1994).


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The sections below discuss the various edible products which have been manufactured using

experimental in-space food production technologies. The constraints and difficulties associated with the

use of each technology have also been laid out.

Algae

Algae have been researched extensively in the early 1950s and 1960s by the United States (US) Military.

The reason algae were selected is due to its high photosynthetic efficiency and their ability to grow in

small spaces. In addition to these benefits, algae is an effective atmospheric regenerator capable of

recycling CO2 to O2. However, the downside of algae is the requirement to process them prior to ingestion.

The significant nucleic acids and indigestible cell wall components present in algae makes them difficult

to eat unprocessed (Lane and Schoeller, 2000).

Recently, the University of Stuttgart is undertaking research on Chlorella vulgaris algae, with an aim to

send an experiment to the ISS. The experiment is to test a hybrid life support system that provides food

production capabilities and atmospheric recycling for crewed missions. Preliminary research has

estimated that 30 percent of human nutrition needs could be filled with algae bioreactor production in

space (Dancer, 2017). Figure 8 displays the algae bioreactor developed by the University of Stuttgart.

Figure 8: University of Stuttgart algae bioreactor (Dancer, 2017).

Microbes

Microbes are organisms which range from harmful and beneficial bacteria, viruses, yeasts, protozoans,

and fungi. While most microbes are considered to be sources of biological contamination or useful

recycling “factories” of biological material, some microbes are also considered as possible food sources

for space activities. For example, many species of fungi are edible and are regularly farmed in controlled

conditions. Microbes do pose specific challenges due to their nature of airborne spreading, which can

become especially complicated in microgravity (Eckart, 1996).

Plants

This section is adapted from Lane and Schoeller’s (2000) publication on bioregenerative life support for

planetary exploration (pre-ISS). Since the early 1950s, the idea to leverage a plants’ photosynthesis ability

for dual uses has been proposed. From one side, plants can provide breathable oxygen by removing


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carbon dioxide while from the other side, plants can create organic compounds that are used as sources

of food in space. Leveraging a varied diet of plants, humans’ nutritional needs can be addressed. It is

suggested that leafy and salad type crops would be favored to supply adequate calcium levels as seeds

are low on calcium levels. Plants for space travel are selected based on their yield to growth area ratio,

amenability to controlled environments, and low processing requirements. After many closed-loop tests

with humans, wheat, cabbage, and broccoli are the top three recommended crops, with wheat being

tested previously aboard the Russian Mir Space Station. An optimal crop mix is essential to provide crew

members with the daily nutritional requirements in terms of carbohydrates, proteins, and lipids. Some

plants produce higher yields in brighter lighting conditions, and as such, illumination aspects should also

be considered for in-space food production needs, with some plants requiring dark cycles, while other

plants being tolerant to constant illumination.

Plants have been grown in the space environment for over 40 years, with the first plant experiments

performed on Salyut 1 during the Oasis 1 experiment in 1971. Since Oasis 1, there have over 20 different

plant experiments on board a spacecraft with over 40 different plant species experimented upon (Zabel,

et al., 2016).

As of 2013, the ISS has been used to test VEGGIE, a deployable plant growth unit that provides the crew

with fresh food. While official data from the experiment has not been released as of late 2018 (NASA,

2019a), VEGGIE is a testbed not only for nutritional and food production, but also for psychological and

radiation protection methods for long duration flights. Having something green from Earth, something

meaningful to do during a mission and the anti-oxidative benefits of fresh plants are all bound into

VEGGIE’s research (NASA, 2015b).

It has been calculated that 10-20 m² of continuously planted area could meet one single astronaut’s O2

needs, while an area of about 30-50 m² would be needed for adequate food production. In addition to

food production and atmospheric recycling, plants also perform wastewater management, with waste

water fed to plants, and transpiration from them providing clean water as collectable moisture (Lane and

Schoeller, 2000).

Animals

Silkworm moth larvae show strong potential for use as an animal protein source for astronauts during

long-term deep space exploration. Silkworm living on mulberry leaves have the following benefits for use

in space: high protein content, reasonable nutrient compositions and ample contents, a short lifespan,

easy breeding method, small growth room, little odor, and wastewater produced (Yang, et al., 2009).

Brinckmann and Schiller (2002) designed concepts for experiments with insects and aquatic organisms

such as rotifers, nematodes, and other small aquatic animals (sea urchin larvae, tadpoles, fish youngsters)

using two ESA facilities which will be available for animal research and other biological experiments on

the ISS: the European Modular Cultivation System (EMCS) in the US Lab “Destiny” and BIOLAB in the

European “Columbus” Laboratory.


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Furthermore, other animals have been considered as a potential source of nutrition for long term

missions. Due to long and complex life cycles of most animals, animals with short life cycles have been

proposed as the most suitable. This could include animals like rapidly reproducing fish species (Eckart,

1994). As an example, Japanese rice fish, medaka, has been used as a research animal aboard ISS. Research

has proven that medaka are relatively unaffected by microgravity and could live full life cycles aboard a

spacecraft with only minor stress related issues (Ijiri, 2003; Murata, et al., 2015). Animals as a food source

will be further considered in Section 2.1.2 of Chapter 2.

2.4 Crew Health

The presence of equipment for crew health holds a significant value on the ISS. As astronauts are carrying

out their expedition, return to Earth is not always possible in a short time. Hence, stockpiles of medical

supplies are required. While an analysis of the likelihood of injuries during a space mission could identify

the crucial medical supplies required, this is not without issue. Unforeseen circumstances may trigger the

need for non-stocked items, multiple injuries may occur simultaneously, or the use of generic devices may

cause significant hindrance to the working requirements of the crew. Furthermore, a minor trauma could

cause fractures abetted by bone demineralization due to microgravity. In any emergency situation, crew

members must be able to respond immediately.

Currently, medical devices and drugs are available in stockpiles which are resupplied to the ISS via cargo

missions. With the improvements in ISM, any risks associated with the aforementioned situations can be

mitigated. The sections below outline the current and developing ISM technologies implemented in the

ISS to provide astronauts with instantaneous access to critical medical devices and drugs.

Medical Devices

Medical devices such as splints can take up valuable volume and mass but may never be needed. On-

demand patient specific medical supplies can provide astronauts with more effective personalized

products. A company, 3D4MD, has developed CAD models for medical supplies which can be uploaded

and printed on the ISS using Made in Space’s Additive Manufacturing Facility (further discussed in Section

3.1 of Chapter 1). This company aims to leverage 3D printing systems to address global healthcare issues

on Earth as well as astronauts’ medical requirements (3D4MD, 2019). Their medical team designed a

digital model of a custom-fitted finger splint as shown in Figure 9. With an on-board 3D printer, astronauts

can now have basic personalized medical supplies during space mission (Davies, 2017).

Figure 9: A customized finger splint 3D printed on the ISS (Davies, 2017).


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Drugs

The medical supply needs can be partially fulfilled by producing antibiotics through microbial processes.

As an example, actinomycin D has been produced onboard of the ISS during a 72- day experiment with a

bacteria species, Streptomyces plicatus. Actinomycin D is ingested to prevent bacterial and tumorous

activity (Koba and Konopa, 2005). It was observed that microgravity increased the rate of early-stage

production of antibiotics relative to terrestrial antibiotic production (Benoit, et al., 2006). Antibiotic

production can prove valuable in confined spaces where infections may be unavoidable and hygiene

conditions may degrade rapidly in comparison to an open environment. Other manufacturing

technologies used on Earth to print personalized patient-specific drugs are discussed in Section 2.3 of

Chapter 2.

2.5 Clothing

Clothing in space is currently a challenge. Designing clothes for use in microgravity has to take into

consideration safety, moisture absorption, and freedom of movement. Hence, the design of clothing has

to be carefully considered (Yamashita and Wheeler, 2014). Furthermore, the size of clothing typically worn

by a crew member on Earth will increase in space due to the elongation of their spine.

For a crew of six, over 400 kg of clothing is supplied to the ISS per year (NASA, 2019f). As there is no

laundry washing facility on the ISS, the crew receives new sets of clothing that are changed periodically

(either daily or weekly) (Stine, 1997; Yamashita and Wheeler, 2014). Dirty clothes are currently jettisoned

from the ISS along with other solid wastes such as trash (Anderson, Barta and Lange, 2015). With the

implementation of ISM, clothes can be 3D printed. Combined with textile recycling capabilities, the cost

of launching a resupply of clothes can be drastically reduced along with the storage volume requirements.

Such technologies can also provide astronauts with personalized clothes that are adapted to their

changing bodies affected by the long-duration microgravity environment.


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3 Additive Manufacturing on ISS

This section of the report will focus on discussing further in detail the current and in-development 3D

printing technologies for the ISS. In-space 3D printing is considered as an infant technology with its first

initiatives in 2014. However, space agencies have placed an emphasis to mature such technologies

because of their ability to reduce spare part mass and resupply missions. This section will go into more

detail about specific products and capabilities of three additive manufacturing technologies on the ISS.

The section will conclude with NASA and ESA initiatives on additive manufacturing.

3.1 Current Techniques

Demo 3D Printer - 2014

To understand the necessity to mature in-space 3D printing technologies, NASA partnered with Made In

Space to develop 3D printing techniques which would efficiently and effectively print in microgravity. In

2014, after extensive testing on a number of parabolic flights the previous year, the 3D Printing (3DP) Tech

Demo was built and launched to the ISS. The printer is displayed in Figure 10 (Made In Space, 2017).

The material used for the printer was Acrylonitrile Butadiene Styrene (ABS) plastic, chosen for its strength,

low toxicity, and ease of use (Prater, et al., 2016). Using forced convection to drive the substrate and

replace gravity, the printer was able to print small parts and tools shown in Figure 11 via Fused Deposition

Modeling (FDM). This demonstrated the possibility to further additive manufacturing capabilities in

microgravity including recycling of waste substrate (Made In Space, 2017).

Figure 10: The 3DP Tech Demo; the first 3D Printer in zero gravity (Made in Space, 2014).


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Figure 11: A sample of 3D printed parts on the ISS for the astronauts (made-in-space-3D-printed-objects,

n.d. and World’s-First-Tool-Made-In-Space-Using-3D-Printing-1, n.d.).

To date, the 3DP has printed over 50 parts (Bean, et al., 2016). The printer was used as a proof of concept

to print two phases worth of mechanical test coupons as seen in Table 1 and 2.

Phase I printed 22 various parts and these parts were sent down to Earth for analytical testing (Bean, et

al., 2016). The parts were found to have superior tensile strength when compared to their terrestrial

counterparts but inferior compressive strength (Bean, et al., 2016). The experimenters at NASA did not

know the cause of the variance but believed that the extruder tip was too close to the build tray which

was remedied during the phase II experiments (Bean, et al., 2016).

Phase II was conducted in 2016 and 34 additional parts were printed. These prints were again sent back

to NASA for analysis on Earth and found that the specimens from phase I and phase II showed no statistical

differences. The source of error was deemed to be a multitude of variables that are uncontrollable and

inherent to the different manufacturing environments (Prater, Werkheiser and Ledbetter, 2018).

However, NASA did conclude that microgravity was not the cause of these variances and considered their

proof of concept complete. Tables 1 and 2 lists the products printed during Phase I and Phase II analysis,

respectively. After the completion of the two phases, NASA concluded that FDM had proven itself

successful in the environment of space.


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Table 1: List of Phase I products (Bean, et al., 2016).

Phase I: Specimen Description

1. Calibration coupon 2. Extruder plate

3. Layer quality specimen 4. Tensile coupon

5. Compression coupon 6. Flexure coupon

7. Negative range specimen 8. Torque coupon

9. Crowfoot 10. Structural clip

11. Positive range specimen 12. Tensile coupon

13. Compression coupon 14. Flexure coupon

15. Tensile coupon 16. Compression coupon

17. Flexure coupon 18. Tensile coupon

19. Microgravity structure specimen 20. Sample container (container)

21. Ratchet 22. Wire tie

Table 2: List of Phase II products (Prater, Werkheiser and Ledbetter, 2018).

Phase II: Specimen Description Quantity

Total calibration coupons 1

Total tensile coupons 12

Compression coupons 14

Layer quality specimens 7

Additive Manufacturing Facility (AMF) - 2016

The next printer utilized on the ISS arrived in 2016, the Additive Manufacturing Facility (AMF). Both the

3DP and the AMF were designed and developed by Made in Space as part of the NASA Small Business

Innovative Research/Small Business Technology Transfer (SBIR/STTR) initiative. The AMF, shown in Figure

12, was implemented for hardware manufacturing services for NASA and the U.S National Laboratory

onboard. The AMF was built with consideration of the expertise developed during the 3DP experimental

phases and also uses the FDM process. As such, the AMF has the capability to print larger and more

complex products in less time than its predecessor (3DP Tech Demo Printer), with multiple aerospace

grade plastics as an input (Made in Space, 2016a). Table 3 provides further specifications of the AMF.


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Figure 12: The Additive Manufacturing Facility (AMF) on board of the ISS (Made in Space, 2016a).

Table 3: Printing capacity of the AMF (Made in Space, 2016a).

Parameter Performance

Volume (mm) 140 L x 100 W x 100 H

Material ABS, HDPE, PEI+PC (upgradable)

X/Y Resolution 0.025 – 0.44 mm with nominal of 0.15 mm

Z Resolution 75 μm layer height

Minimum Wall Thickness 1 mm

Threaded Holes >M10

Power Consumption 600 W

The AMF has produced over 100 parts to date (Prater, Werkheiser and Ledbetter, 2018). The printer is

owned and operated by Made In Space and examples of parts created for the ISS are shown below in

Table 4 (Werkheiser, 2018). In addition to the parts in Table 4, other parts manufactured by the AMF are

as follows: Allen wrenches, clothespins, cable mounts, buckles, cable ties, nuts, bolts, sockets, bottles, ball

valves, medical devices, springs, and many more (Made in Space, 2016b).

Table 4: Examples of AMF products printed on the ISS (Werkheiser, 2018).

Specimen Name Purpose Creating Date

SPHERES Tow Hitch Joins 2 satellites together during flight. February 2nd, 2017

REM Shield Enclosure Radiation Monitor Brackets March 20th - June 16th, 2017

Antenna Feed Horn Space communication and navigation March 9th, 2017

OGS Adapter Adapter for OGS air outlet and fixture July 19th, 2016


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Refabricator - 2018

Tethers Unlimited Incorporated (TUI) received approximately USD 750,000 as part of NASA’s SBIR

initiative to develop the Refabricator, a proof of concept 3D printer and closed-loop recycler delivered to

the ISS in November 2018 (NASA, 2019b). The Refabricator, shown in Figure 13, can print tools and parts

using plastic filament that can be made from recycling previously made plastic parts. The printer would

allow effective re-use of the material from all printed parts when they are no longer needed. The

Refabricator is currently undergoing testing on the ISS, and is the first integrated recycler and printer in

space (NASA, 2017a).

Figure 13: The Refabricator (NASA, 2017a).

3.2 In-Development Techniques

The Refabricator was the final printer to date that has been installed on the ISS. However, many additive

manufacturing techniques are currently under development with plans to launch their 3D printers in the

upcoming years.

NASA Initiative

For the ISS, there are a number of systems that are currently being developed under the SBIR award. This

award is categorized into three phases. In Phase I, systems are defined as establishing technical feasibility

and concept and are awarded at a maximum of 125,000 USD in 2018. Phase II efforts include further

development, R&D, and prototypes from Phase I and are awarded a maximum of 750,000 USD in 2018. In

Phase III, these systems have been planned for commercialization and infusion as well as for flight on the

ISS. This is the phase where hardware for current ISM payloads such as Refabricator were developed

(Prater, et al., 2018). Examples of systems in Phase I and Phase II can be found in Table 5 below.


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Table 5: Systems in Phase I and II of NASA’s ISM technology development efforts (Prater, et al., 2018).

System Name Phase Function Materials Company

Vulcan Advanced Hybrid Manufacturing System

Phase II Fused filament fabrication (FFF), weld based AM and automated part movement

Multi-material, hybrid manufacturing

Made In Space

Heat Melt Compactor (HMC)

Phase II

Compresses and heats 1 kg of solid non-biological waste (packaging) to produce 200 ml of water and a compact foam tile.

Solid non-biological waste.

NASA

The ISS Fabrication Laboratory (FabLab) using Ultrasonic Additive Manufacturing Technology (UAM)

Phase II

Creates solid state bonds in various metal composites and materials. Milling and welding of finished parts as well as embedding sensors, and producing new composites

Aluminum alloys, metal composites, metal foils. UAM removes the oxide layer by using sound waves (metal foil)

Ultra Tech Machinery

Metal Advanced Manufacturing Bot-Assisted Assembly (MAMBA)

Phase II Metal manufacturing and recycling

New or scrap metals pressed into a metal ingot

Tethers Unlimited

ERASMUS Phase II ‘Medical-Grade and Food-Safe Plastic Recycling and Sanitation System'

Recycled materials (plastics) using a dry heat sterilization and UV sanitization

Tethers Unlimited

Sintered Inductive Metal Printer with Laser Exposure (SIMPLE)

Phase II

Metal printer with filament heated through induction and deposited. Melt completed by a low power laser

Ferromagnetic wire-fed metal filament

Techshot

Customizable Recyclable International Space Station Packaging (CRISSP)

Phase II

3D foam packaging from recycled materials. Phase II-X will upgrade the Refabricator system and use materials from it

Plastic recycled from the Refabricator into filament - Material study in progress

Tethers Unlimited

Reversible Copolymer Materials for FDM 3D Printing of Non-Standard Plastics

Phase II

Recycling and blending of materials into usable polymer filament. Phase II-X will conduct further material characterization

Thermally-reversible polymer materials with FFF

Cornerstone Research

Group (CRG)

Software and Tools for Electronics Printing in Space (STEPS)

Phase I Software that complements NASA's effort in printable electronics

Software Techshot

Adaptive laser sintering for in-space printed electronics

Phase I Adaptive Laser Sintering System (ALSS) for printed electronics

Metal Inks, low Tg Polymer substrates

Optomec


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Furthermore, a new ISM project award as part of NASA’s Next-STEP program was announced in December

2017. This project is a Multi-Material Fabrication Laboratory (FabLab) that seeks to have a high level of

autonomy and should be able to integrate a suite of manufacturing capabilities. Some of the capabilities

of FabLab were the ability to manufacture metals, ceramics, electronics and biological tissues in

microgravity. The FabLab is suggested to fit within the current Expedite the Processing of Experiments to

Space Station Racks (EXPRESS racks) on the ISS, including power and mass restrictions. In addition, it

should possess terrestrial and autonomous quality control. The project is currently in the initial stages

with three companies working on it: Techshot, Tethers Unlimited, and Interlog Corporation (Prater, et al.,

2018).

ESA Initiative

The European Space Agency (ESA) has student initiatives focusing on expanding the capabilities of additive

manufacturing in space. An example of this is the Grain Power team, abbreviation of Gravity Independent

Powder-based Additive Manufacturing. They have proposed to demonstrate the feasibility of powder-

based additive manufacturing in microgravity by flying a prototype powder-based 3D-printer working in

microgravity. This project was selected to partake in the European Space Agency program “Fly Your

Thesis” and will fly on the ESA parabolic flight campaign in November 2019 (ESA Fly your Thesis, 2019).


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4 Other Manufacturing on ISS

As previously mentioned in the introduction, ISM includes other manufacturing technologies involving

recycling, assembly, biological, and chemical processes. This section will focus on discussing the assembly

techniques featured on the ISS, both onboard and it’s exterior.

Project Archinaut

Made In Space has initiated Project Archinaut, a NASA funded project that was initiated in 2015 together

with Northrop Grumman Corporation and Oceaneering Space Systems. The goal of Project Archinaut is to

“enable autonomous manufacture and assembly of spacecraft systems on orbit” (Made In Space, 2018).

Two projects which employ the Archinaut technology are underway: the first is Dilo, a spacecraft that

transforms into a large reflector, while the second is Ulisses, a free-flying robot that manufactures and

assembles large structures in space. The ISS is expected to be used as a platform to test Project Archinaut

under microgravity environment since the prototype might require maintenance and calibration.

Canadian Robotic Arm

Currently, with the development of robotic technology, increased agility and dexterity can be witnessed

during the assembly and maintenance tasks conducted with the Canadian-built Mobile Servicing System.

The system contains the Space Station Remote Manipulator Systems (SSRMS) and the Special Purpose

Dexterous Manipulator (SPDM) (Flores-abad, et al., 2014). The SSRMS, also known as Canadarm2, was

launched and installed on the STS-100 Mission in 2001. It is a 17-meter long robotic arm that has seven

degrees of freedom and a symmetric structure capable of moving around the ISS like an inchworm. The

Canadarm2 is operational on the ISS to fulfill the critical missions such as the ISS assembly and operation.

It also plays a key role in the construction of the ISS (Flores-abad, et al., 2014).

A small, dexterous two-armed robot, SPDM is Canada’s other contribution to ISS. Since it features a 15

degrees of freedom dual-arm configuration, it can undertake highly dexterous tasks, such as installing,

removing and servicing small payloads and Orbital Replaceable Units, with the help of Canadarm2. During

operations, the Canadarm2 carries the payload within the SPDM’s range for repair, or picks up the SPDM

and positions it close to the payload that requires servicing (King, 2001).

Figure 14: Shuttle Remote Manipulator System and Mobile Servicing Systems (Jordan, 2011).


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European Robotic Arm

The European Robotic Arm (ERA) will be fixed to the Russian segment of the ISS. It is an 11-meter and

seven degrees of freedom manipulator with two booms and a transferable base. The special tasks of the

ERA include the installation, deployment and replacement of solar arrays as well as the placement of

Orbital Replaceable Units (Laryssa, et al., 2007). The ERA has yet to be launched to the ISS. The system

was expected to be launched on a Proton-M rocket in late 2019 but it has been postponed to 2020

(Cruijssen, et al., 2014; Aziz, 2019).

Figure 15: European Robotic Arm (ESA, 2006).

Japanese Experimental Module Remote Manipulator System

Japanese Experimental Module Remote Manipulator System (JEMRMS), developed by JAXA, is composed

of two arms with 6 degrees of freedom, a 10-meter long main arm with 6 degrees of freedom and a 2.2-

meter long small fine arm. The main arm, which consists of booms, joints, television cameras, camera pan

tilt unit, light and end effector, is attached to the Japanese Experimental Module Pressurized Module. The

small fine arm will be attached to the end of the main arm and can perform agile tasks, such as exchanging

the Exposed Facility (EF) with the main arm or placing Orbital Replaceable Units (JAXA, 2019).

Figure 16: Japanese Experimental Module Remote Manipulator System (Robinson, et al., 2008).


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Robonaut

Robonaut 2 (R2) is a humanoid robotic platform manufactured by NASA and General Motors. It has been

tested on the ISS to take on tasks that are traditionally performed by astronauts. It incorporates force

sensing, thus allowing gentle operations to be performed with high dexterity. It is designed to be operated

by people through interactive interfaces (Diftler, et al., 2019). R2 is still limited to very structured tasks

and the ability to perform flexible tasks is still lacking. As such, complicated tasks will remain for now in

the domain of astronauts’ EVA. R2 also requires special robotically compatible interfaces. It can attach

itself using grippers to handrails and seat tracks (Badger, n.d.). R2 is supposed to relieve astronauts from

EVAs, dangerous and/or hazardous, rapid responses and physically demanding tasks, and has proven its

usefulness in test situations.

Figure 17: Robonaut 2 onboard ISS with astronaut Steven Swanson (Badger, n.d.).


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Chapter 1 Summary

This chapter established a framework for ISM that will be further utilized and expanded upon in Chapter

2. The current failures on the ISS will be leveraged to identify areas of further study while the crew needs

set a baseline to compare and contrast against the deep space mission crew needs for a period of 3 years

with no resupply. Current manufacturing technology has been identified to mitigate the risks of deep

space while developmental technologies will be further elaborated upon along with their future

applications for a sustainable spacecraft. Chapter 2 will determine the boundary conditions associated

with a 3-year deep space mission and analyze solutions including feasibility, challenges, and risks.

TER ONE

C

C DEEP SPACE CREWED MISSION

CHAPTER TWO

Chapter Two: Deep Space Crewed Mission

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1 Mission Type

The current achievements and successes in space drive humans to push the exploration boundaries

further. There has been discussion of humans going back to the Moon and even exploring as far as Mars.

However, with these dreams come many challenges. This section will attempt to resolve some of these

challenges with the implementation of ISM in those dreams. This section will build upon the foundation

laid out in Chapter 1: ISS Analogue. However, prior to establishing the potential of ISM in a crewed deep

space mission, a number of educated assumptions must be outlined. This section will outline the

assumptions in regards to the location, duration, and crew size.

Location

Regardless of the mission destination, space agencies and private companies are investing into long

duration crewed deep space exploration missions. In fact, NASA, SpaceX and the Russian Government

have laid out plans and desires to go to Mars in the coming years (Dunbar, 2018; Foust, 2018; Torossian,

2018). Hence, the location of this mission is assumed to be in deep space which is defined in the

Introduction of this report as beyond the GEO. A particular celestial body has not been chosen as the

destination since governments’ space priorities and plans are subject to frequent changes and redirection.

For example, NASA under the Obama administration was tasked to focus on asteroid mining, while under

the Trump administration, NASA’s focus has been shifted towards the Moon as a pit-stop to Mars (Patel,

2017; Leary, 2017).

Nevertheless, this deep space mission will need to feature ISM capabilities to increase the spacecraft’s

autonomy while reducing costs. Due to the assumption that the spacecraft is in deep space, the

practicality of cargo resupply is reduced. In fact, it is assumed resupply missions to this mission are not

viable due to the enormous velocities and distances to overcome in a transfer trajectory (Saunders, 2017).

Duration

Now that the location and term “deep space” has been established, the time period over which this

mission will take place must be defined. According to NASA, a crewed mission to Mars can potentially take

up to three years, considering (i) the time it takes to reach Mars from Earth, (ii) the time it takes to orbit

Mars and perform research experiments and (iii) the time it takes to come back to Earth. Due to the

relative positions of Earth and Mars during their orbits around the Sun, the distance between the two

planets varies, thus allowing an optimal launch or return window to occur once every approximately two

years (Frost, 2016). Although the location of this mission is not to Mars but to an arbitrary point in deep

space, the maximum duration which is obtained from mission analysis is assumed for this mission as well.

This is to ensure the full potential of ISM is exposed and exploited. Furthermore, NASA’s analysis for a

mission to Mars also corroborates the need to eliminate mission reliance on cargo resupply and introduce

ISM.


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Crew Size

Currently, the ISS is populated by a maximum crew of six people. However, once US commercial crew

vehicles become operational, the ISS crew size will be expanded to seven people (NASA, 2015a). Using the

ISS as an analog, the assumption has been made that future deep space missions will need to

accommodate a maximum of seven crew members. A relatively large number of crew members decreases

social monopoly and escalation of internal conflicts while maintaining a high stimulus environment.

Hence, for the purpose of this report, it has been assumed that ISM technologies will be assessed under

the framework of supporting a three years mission into deep space hosting a crew of seven crew

members.

Since deep space crewed missions feature a different set of requirements when compared to the ISS

missions, this chapter first introduces the critical factors that need to be considered for a deep space

crewed mission from a human perspective as well as a spacecraft perspective. Afterwards, the report

discusses how 3D printing and other manufacturing technologies can potentially be leveraged or adapted

to address the critical factors previously mentioned. Following this section, a Technology Readiness Level

(TRL) timeline for the different manufacturing technologies is provided, along with the challenges and

risks associated with each technology. Finally, the financial, legal, political, ethical and environmental

considerations of ISM are discussed.


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2 Human Factors

A deep space crewed missions, as described in the prior section, has more stringent crew demands

compared to the ISS. Since the crew will be exposed to radiation and solitude from Earth for a longer

period, the crew needs are more significant. Figure 18 lists and illustrates the habitation system elements

that are crucial for the crew of current space habitats such as the ISS as well as the expected future deep

space habitation system elements.

Figure 18: Diagram of current ISS and required future habitation systems elements according to NASA

(Crusan and Gatens, 2017).

The sections that follow will discuss the particularities of a deep space mission compared to the ISS in

regards to human factors. These factors include: (i) critical crew needs, (ii) waste management, (iii)

medical supplies, and (iv) medicine. Once the differences in the two missions are established, technology

which may have the potential to fill the requirement gap will be proposed.


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2.1 Critical Crew Needs

Although humans have numerous requirements in order to survive a three-year deep space mission, this

section will discuss the critical needs which are basic to life: (i) atmosphere, (ii) food, and (iii) water. Once

the critical requirements are established, a technology to meet those requirements will be proposed.

2.1.1 Requirements

The current crew requirements on the ISS for atmosphere, water, and food are discussed previously in

Section 2 of Chapter 1. By extrapolating that data to seven crew members and three years, Table 6 is

produced.

Table 6: Closed-loop efficiencies for Oxygen, Food and Water for a 3-year mission of seven members.

Requirement 1 person per year Total for Mission

Oxygen 303 kg 6,363 kg

Food 226 kg 4,746 kg

Potable water 1,300 kg 27,300 kg

Hygiene water 9,490 kg 199,290 kg

The total mass of critical needs equates to 237,700 kg. This is the mass that is required if the mission were

to depend solely on resupply missions. However, this mission is considered to be sustainable which means

these requirements are to be satisfied by use of ISM, more specifically recycling. Referring back to figure

18, the efficiency of the current “closed” loop systems needs to be increased to 75% and 98% for O2

recovery from CO2 and H2O recovery, respectively. After performing the calculations, as shown in Table 7,

the total mass saved is approximately 20,190 kg. This mass is saved in the initial mass of the cargo

launched with the crew.

Table 7: Mass savings with increased recycling rates.

Requirement ISS

Recycling Rate

Ideal Recycling

Rate

Resupply with ISS Rate

Resupply with Ideal Rate

Mass Saving

Oxygen 42% 75% 3,690 kg 1,590 kg 2,099 kg

Potable water 90% 98% 2,730 kg 546 kg 2,148 kg

Hygiene water 90% 98% 19,929 kg 3,985 kg 15,943 kg

However, there is still a requirement for a large initial mass of critical crew needs in order to sustain seven

crew members for three years as the recycling rates are not 100%. Hence, other ISM techniques which

are more efficient need to be considered to provide higher recycling rates.


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Furthermore, the food requirements on the ISS are currently being satisfied solely by resupply missions.

This cannot be the case for a deep space mission since a resupply will be very time consuming and cost

ineffective. The food can also be launched with the initial cargo with the crew. In total, this would amount

to approximately 4,700 kg of food (dry weight) for seven crew members for three years (Anderson, Barta

and Lange, 2015). This amount of food would need to be stored for the whole flight duration. For such a

mission, ISM of food is needed to fulfill the food requirements without excessive mass during launch.

2.1.2 Technology

One type of ISM technology that may fulfill the atmosphere, water and food needs of crew members is

bio-regenerative systems (Eckart, 1994; Lobascio, et al., 2008). The most important component of a bio-

regenerative systems is photosynthesis. This process can perform most of the major functions for life

support systems (Eckart, 1996). An example of photosynthetic effects on life support is discussed in Table

8.

Table 8: An example of a bio-regenerative Hydroponic Plant Growth Facility’s (HPGF) impact on in-space

food production and atmospheric recycling capabilities (Lobascio, et al., 2008).

Parameter Value

Cultivated surface 30m2

Cultivation volume 25m3

Tentative menu (% of edible mass) Soybean (14%) – Wheat (41%) – Dry bean (21%) – Lettuce (24%)

Caloric energy amount production 4475 kJ/day (38% of total need of one crew member in one day)

Macronutrient contribution per crew and day Carbohydrates: 43% - Proteins: 41% - Lipids: 22%

Food production (fresh basis) per day 435g

Water transpired per day 150kg (need of 5 crew members)

Oxygen production per day 863g (100% of need of 1 crew member)

CO₂ removal per day 1187g (120% of need of 1 crew member)

Air temperature in the HPGF 20 to 28 °C

Relative humidity in the HPGF 75%

CO₂ concentration in the HPGF 300 μmolCO2/molair

Pressure in the HPGF 101325 Pa

In the following sections, atmospheric, water, and food needs, and the impact of possible bio-regenerative

systems in space are explored in further detail.


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Atmosphere

Bio-regenerative systems can be used to replenish atmosphere. With current ISS systems based on

mechanical gas purification, bio-regenerative systems can fulfill the role of a CO2 scrubber by using

photosynthetic reaction to convert CO2 to O2 (Eckart, 1994). The opposite is also true, and biological

systems can be used to convert organic waste to atmospheric gases like CO2 or CH4, which then can be

used to fuel further biological growth or to create spacecraft fuel (Eckart, 1996).

Water

Some bio-regenerative systems can utilize high amounts of water, as shown in Table 8 (Lobascrio, et al.,

2008). However, bio-regenerative systems are also effective at recycling water, as some systems operate

using wastewater as an input. As biological components like plants or microbes absorb and consume the

nutrients and impurities from the wastewater, they produce clean water that can be gathered by moisture

collectors installed on the spacecraft and can then be converted to consumable water (Lane and Schoeller,

2000). Two options of bio-regenerative systems for water reclamation from organic material exist: (i)

aerobic bioreactors and (ii) anaerobic bioreactors. In aerobic bioreactors, microbes break down organic

material to their base constituents (CO2, H2O, NH3 and biomass/sludge) in the presence of oxygen.

However, in anaerobic bioreactors, where microbes don’t require oxygen, organic material is broken

down into methane, CO2, and biomass/sludge (Eckart, 1996).

Food

One option to fulfill the food requirements would be to grow food in space which may be achieved by

utilizing hydroponics or aeroponics to produce fresh plants. It has been estimated that farming plants

would need 30-50 m2 of farming area to fulfill one person’s nutritional requirements (Lane and Schoeller,

2000; Lobascio, et al., 2008). With a crew of seven people, potential farming requirement would be 210-

350 m2 to satisfy full complement crew daily nutritional needs. However, this is impractical due to the

high area requirements.

Second, bioreactors can be used on the ISS to grow microbes based food. Although these microbes have

significant nutritional value and fast production rates, an additional processing technique is required.

Without a processing technique, these microbes are not edible. Further research on compact processing

techniques for algae needs to be conducted.

Lastly, insects and/or animals can be utilized as fresh food sources. Insects have been explored as a food

production option for space flights due to their fast reproduction and waste processing capability. As

insects could eat leftover organic waste to grow biomass, they could be a good nutritional supply for

astronauts and recyclers (Parry, 2007). Furthermore, animal cell lines can be grown to produce meat in

laboratory conditions from cell cultures (Schwartz, 2016). These meat cells could then be combined with

3D printing to produce palpable food for astronauts without real animals. The 3D printing of animal

protein could also open the window for more visually pleasing products during spaceflight. This could

increase astronaut’s morale during long term missions (Terfansky, et al. 2013).


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2.2 Waste Management

As with any system dealing with crew, particular attention must be paid to the waste produced and its

disposal. This section extrapolates the waste data from the ISS and calculates the expected waste to be

generated on a three-year deep space mission with seven crew members. Afterwards, multiple solutions

to manage the waste are proposed.

2.2.1 Requirements

As proven on the ISS, waste includes a variety of material, including wastewater, carbon dioxide, food

packaging, clothing, cleaning materials, electronics, and broken parts, among others. Some of this waste

is recycled to minimize the need for resupply such as water that is largely reclaimed but a certain amount

of brine is left over that cannot be reused. The overall levels of waste for a crew of three for one year are

detailed in Table 9 below.

Table 9: Breakdown of ISS waste for three people per year (Anderson, Barta and Lange, 2015).

Waste Product Mass (kg) Method of Disposal

Methane 224 Vented

Carbon Dioxide 522 Vented

Solid waste (clothing, trash, etc...) 1,248 Jettisoned (reentry)

Brine 352 Jettisoned (reentry)

Total 2,346

This translates to 16,422 kg for a crew of seven for three years that must either be jettisoned or vented.

While biological waste, methane, carbon dioxide, and brine may have use in a bio-regenerative system

(outlined in the above section), the remaining solid waste (approximately 7,203 kg) can be stored, limited

by onboard space, or simply jettisoned on route (Anderson, Barta and Lange, 2015). This mass can be

lowered with new types of food packaging and clothing that have been developed and tested on the ISS

(Broyan, Chu and Ewert, 2014). With this capability, zero waste would be the end goal. Otherwise, other

methods of disposal must also be developed.

2.2.2 Technology

There are four ISM techniques which can be implemented to manage the waste which will be produced

by the mission: (i) input to bio-regenerative system, (ii) used as fuel, (iii) input to compactor, and (iv) input

to the Refabricator. All these techniques, excluding the compactor, recycles the waste produced. The

following sections will further discuss these techniques.

Bio-regenerative System

One of the important functions of bio-regenerative systems is also their ability to recycle biological

material. Organic waste created by human metabolism, food waste, or dead tissues is a major waste class

in bio-regenerative systems and recycling these back to nutrients can fuel further growth cycles for plants


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and other organisms. As ordinary waste treatment facilities are too large for spacecraft uses, two main

methods have been identified to recycle organic materials in space:

1. Aerobic bioreactors that use oxygen to convert liquid waste and solid waste back into inorganic

and organic compounds;

2. Anaerobic bioreactors that do not use oxygen to convert solid wastes and possible liquid wastes

to organic and inorganic compounds (Eckart, 1996).

Table 10: Comparison of aerobic and anaerobic waste treatment (adapted from Eckart, 1996).

Aerobic Bioreactor Anaerobic Bioreactor

Use ● Liquid Wastes ● Maybe composting of solid wastes

● Solid Wastes ● Possibly treatment of liquid wastes

Wastes Biologic decomposable fractions of liquid and solid wastes.

Biologic decomposable fractions of liquid and solid wastes

Output CO2, H2O, NH3, (NO2, NO3), biomass/sludge

CH4, CO2, (H2), biomass/sludge

Advantages ● Transition from an insoluble to a soluble state may limit the production rate

● Basic system for the treatment of liquid wastes

● No gas consumption ● No leakage problems ● Methane may be used as fuel ● Small amounts of well stabilized

sludge may be used as fertilizer.

Disadvantages ● O2 -consumption ● CO2 -production ● Microbial activity may be influenced

by toxic components

● Methane production ● Danger of inflammation of Methane ● Slow decomposition ● Very good controlling required ● Microbial activity may be influenced

by toxic components

Fuel

As shown in Table 9, the total mass of methane vented into space is 224 kg per year. Although it is difficult

to recycle this excess methane within the ISS, it can be converted into fuel for propulsion (Anderson, Barta

and Lange, 2015).

Space X is currently developing a rocket engine based on methane. This fuel has advantages of being

relatively dense with a higher melting point than hydrogen, therefore, easier to store (Clark, n.d).

Heat Melt Compactor

The Heat Melt Compactor (HMC) is being tested to take 1 kg of leftover solid, non-biological waste in the

form of packaging and other material, and extract up to 200 ml of water from it, with the remainder being

compressed into foam tiles to be stored. This would create 1,200 kg of water and reduce the waste from


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approximately 7,203 kg to 4,800 kg. The foam tiles that are produced from the process could be potentially

used to create privacy partitions, acoustic separations, and even radiation protection. Beyond the

organizational and safety uses, such dividers would also have potential psychological benefits. Throughout

the mission, the foam tiles would be assembled together as they become available to create these

structural elements, offsetting the need for overall structural mass for a deep-space spacecraft (Broyan,

Chu and Ewert, 2014). This minimizes volume for storage by 70-90%. Another factor in the handling of

waste is the possible contaminant and microbial growth. The HMC includes a process of sterilization (via

heating) in order to minimize this crew risk. This has been tested on the ground, with plans being made

to install the system on the ISS, meeting all physical requirements of use alongside human spaceflight

systems, including power (peak draw of 1 kW) (Fisher and Lee, 2016).

Refabricator

Another method of disposal is the Refabricator by Tethers Unlimited Inc. (TUI), mentioned in Section 3.1

of Chapter 1. This device is the integration of two subsystems: a recycling plant and a 3D printer. Discarded

plastics are placed in the recycler, heated to the point of melting and converted into high-quality filament,

repurposing the material to serve as feedstock for the printer. This subsystem then fabricates new parts

and tools with a range of applications going from food utensils to medical equipment. At this time, the

Refabricator has only been designed to handle Utem, a sturdy plastic, but with limited uses. It is hoped to

upgrade the system to utilize High-Density Polyethylene (HDPE), which has medical applications

(Saunders, 2017). The device as-is is being confirmed to be safe for human use and is currently aboard the

ISS for further testing (NASA, 2019b). In order to deal with metals, another device with similar applications

is currently being designed: the Metal Advanced Manufacturing Bot-Assisted Assembly (MAMBA, also

from TUI), with components under construction and testing, with a prototype slated for full integration

(Prater, et al., 2018).

2.3 Medicine

2.3.1 Requirements

The viability of long duration crewed space missions heavily relies on the crew’s health. On the ISS, the

crew’s health plan is considered for relatively short stay periods and relies on the possibility of using the

Soyuz for emergency evacuation to return to Earth within three to four hours (NASA, 2017d). For deep

space missions, this luxury is unavailable. According to Jones, et al. (2004), there are no medical issues

that would completely stop the first expeditionary missions to Mars given sufficient redundancy in life

support systems. Yet, for a three year mission, a spacecraft must still provide a robust and complete

medical system which can provide for a wide variety of medical issues, and a palliative capability must be

available where resources are limited (NASA, 2017d). NASA (2018d) has identified the risk of

‘unacceptable health and mission outcomes due to the limitations of inflight medical capabilities’ as

inappropriate for three year missions. One of the main causes being that there is no current capability to

minimize medical system resource utilization during exploration missions. Utilizing new technologies such

as 3D printing can significantly help in solving this problem.


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2.3.2 Technology

Due to the crew size of seven, and the increased likelihood of medical issues arising, the amount of drugs

that are needed for a crewed deep space mission significantly increases. The current solution for drug

supplies is storage and resupply. There are a number of different processes and technologies to could be

utilized to change this limitation. A number of technologies are discussed below. These technologies are

all either developed terrestrially or being developed terrestrially as the technology is relatively new.

Inkjet printing

This technique works by depositing tiny droplets of “ink” (other materials such as an excipient may also

be used) onto a substrate. A thermal inkjet printers work by heating up the nozzle, which creates tiny air

bubbles that then collapse leading to pressure pulses that eject ink droplets in volumes as small as 10 - 15

pico-liters. This allows for greater precision and the droplet size can be adjusted by changing the

temperature gradient (Ventola, 2014).

Thermal inkjet printing has been demonstrated to produce solid dosage forms of prednisolone (a steroid

medication which has been used to treat allergies and inflammatory conditions) (Meléndez, et al., 2008).

Inkjet printing has been used to develop nanoparticles and implants containing antibiotics (Gu, et al.,

2012; Huang, et al., 2007), as well as folic acid nanosuspensions (Pardeike, et al., 2011).

Fused Deposition Modelling (FDM)

FDM is similar to thermal Inkjet printing, but instead of releasing ink, beads of heated plastic are ejected.

This also means that the beads of plastic fuse to one another and previous layers before gradually cooling

down. This technique often uses the same thermoplastics that are used in injection molding and as such,

the products produced have similar stability, durability, and mechanical properties (Ventola, 2014). FDM

has been demonstrated to produce anti-inflammatory and antibiotic tablets (Goyanes, et al., 2015).

ZipDose

ZipDose technology has been developed by Aprecia Pharmaceuticals and have produced levetiracetam

tablets (used to treat epilepsy) which is the first 3D printed drug to be approved by the Food and Drug

Administration (FDA). The ability to 3D print the drug, removes the need for compression in the

manufacturing process and therefore can achieve a large dose of the active ingredient (1000 mg of

levetiracetam). An additional benefit from this method is that the tablet rapidly disintegrates with the sip

of a liquid (Aprecia Pharmaceuticals, 2015). This process is the most developed technology for the 3D

printing of medicine in terms of TRL, Manufacturing Readiness Level (MRL), and its approval from the Food

and Drug Administration (FDA).


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Established Technologies

Table 11: Examples of pharmaceutical formulations that were developed by 3DP technology

(Jassim-Jaboori and Oyewumi, 2015).

3DP Technology Dosage Forms Active Ingredients Drug use

Inkjet 3DP

Implant Levofloxacin

Antibiotic for treatment of acute bacterial sinusitis, pneumonia, urinary tract

infections

Nanosuspension Folic Acid A synthetic form of vitamin B9

Nanoparticles Rifampicin Antibiotic for treatment of tuberculosis, leprosy, and

Legionnaires’ disease

Thermal Inkjet (TIJ) Printing

Solution

Salbutamol sulphate Nebulizer used to treat

wheezing and shortness of breath

Prednisolone

Steroid medication used to treat certain types of allergies,

inflammatory conditions, autoimmune disorders, and

cancers

Fused Deposition Modeling (FDM)

Tablet

5-aminosalicylic acid (5-ASA, mesalazine) and 4-aminosalicylic acid (4-

ASA)

5-ASA - An anti-inflammatory drug used to treat

inflammatory bowel disease 4-ASA - An antibiotic primarily

used to treat tuberculosis

3DP extrusion-based printing

Tablet Captopril with

Nifedipine and Glipizide

Angiotensin-converting enzyme inhibitor used for the

treatment of hypertension and some types of congestive

heart failure

A laboratory- scale 3DP machine

Capsule Pseudoephedrine

hydrochloride

Decongestant that shrinks blood vessels in the nasal

passages

3DP machine Multi-drug implant Rifampicin and

Isoniazid Anti-tuberculosis medication


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Advantages of 3D printing medication

There are three major advantages that come with the 3D printing of medicine over conventional

manufacturing methods:

1. Personalized drug dosing

2. Unique dosage forms

3. Complex drug-release profiles

Personalized drug dosing is one of the most evident advantages. The ability to change the size of each

tablet or form allows the dosage to be adjusted. This not only reduces waste due to production of standard

form sizes but also allows for specific customization to suit the patient. With a potential crew of 7 people,

the ability to produce person specific drugs, saves on storing a vast amount of drugs for every crew

member and drug wastage. One potential application of personalized drug dosage is the production of

drugs that can facilitate faster recovery from radiation damage (radio-protectants). These drugs could be

printed in advance if there is a known increase in radiation exposure. The dosage of these drugs could be

increased or decreased depending on the severity of the exposure.

Figure 19: FabRx’s chewable medicines showing different dose sizes (FabRx, 2018).

Unique dosage forms allows for the drug to not just be printed in a tablet or capsule form but another

form that may be more suited to the user. In a microgravity environment, this may be a great capability

for both the patient and the process. Allowing different forms of administration through manufacturing

techniques on board greatly increased the adaptability of the drug production.

Complex Drug profiles are now becoming a much more researched topic due to the development of 3D

printing. Traditionally, drugs have the active ingredient and substrate together in a homogeneous mixture,

now however, 3D printers can print barriers between active layers only 200 microns thick allowing for

controlled drug release (Ventola, 2014). Administering multi-layer drugs, with steady state release or

pulsating mechanisms allows crew members to reduce the time allocated to medication and can also ease

the use of medication.


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2.4 Medical devices

2.4.1 Requirements

As discussed in Section 2.3 of this Chapter, future long duration exploratory missions with decreased

access to support from Earth will require on-board medical personnel and equipment to be more effective

and independent. Currently on the ISS, a medical condition could be resolved more easily than the same

medical condition occurring in deep space.

On the ISS, there are several medical kits (NASA, 2016b):

1. Medical diagnostic pack - blood pressure cuff, thermometer, oximeter, stethoscope, etc.

2. Medical supply pack - such as bandaids, tapes, gloves, needles, and syringes.

3. Minor treatment pack - Bandaids, gloves, dental kit.

4. Oral medication pack.

5. Physician equipment pack - minor surgery kits.

6. Topical and injectable medication pack.

All of these packs contain many disposable pieces of equipment in addition to other routine testing

consumables. It can be seen that an important part of the weight is used for medical consumables. In

addition to this, many of these parts are stored but never used (Owens and de Weck, 2016).

ISM can help enable deep-space missions by reducing the stored current medical supplies and related

weights. In addition to this, the flexibility of design that becomes available when using additive

manufacturing enables for the creation of new types of consumables. This allows for new approaches to

be taken when it comes to medical devices for use in spaceflight.

Current on Earth 3D printing technologies have proven capable of printing medical related plastic

consumables and medical graded materials. These methods will be evaluated for space mission

requirements.

2.4.2 Technology

In the medical field, consumables are usually syringes, catheters, tubes, and needles that are mainly

simple parts made out of plastics or metals. These components are made for one-time use in order to

maintain patient personal hygiene and reduce the spreading of infections between crew members (NASA,

2016b). The feasibility of 3D printing methods in supplying these needs will be further described.

General Plastics and Polymers Consumables

3D printing of medical consumables on Earth is not very commercialized yet since it is much cheaper to

mass produce by molds. However, in space from reasons previously described it can still be worthwhile

to print the consumables. When looking at production of consumables in space, the most obvious

technologies are plastics which are already proved as operational technology in space. Figure 20 shows

some of the different medical consumables that have been printed using current 3DP technology.


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Figure 20: Surgical tools, splint, face mask, otoscope and a fitting (3D4MD, 2019; 3D printing Industry,

2019).

When looking at long exploration missions, the variety and amount of these consumables will be very

high. Medical surgery may be a matter of essence when astronauts will be staying longer periods without

the possibility of returning to Earth and consumables will not be replenished at the same frequency as is

currently being done on the ISS.

3D printing plastics terrestrially is quite developed and is used in high-end medical operations where

specialty and customized tools are required. These tools and components are printed by the technologies

presented in Table 12.

Table 12: Printing technologies for medical devices (Engatech, n.d.; Stratasys, 2019).

3DP technology

Material Resolution Usage Bio compatibility

Sterilization

Polyjet Thousands of materials with different thermal behavior, transparency, rigidity and color such as ABS, ASA, MED610 provided by Stratasys.

<100 micron Complex prints with different characteristics in one print. Detailed and smooth precise finishes. Highly flexible.

Yes No

Fused Deposition Modeling

Tens of materials such as ABS, PPSF, Nylon.

>100 micron Durable, tough, thermoresistant, tight tolerance components

Yes Yes

DMLM Stainless steels, Chrome-cobalt alloys, Bronze, Nickel and aluminum alloys

20 microns Metallic tools of all kinds with high finish

Yes Yes


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These technologies have been proven to be capable of sterilizing the final product through the printing

process and can use many biocompatible materials. In addition to these processes, the company ‘Copper

3D’ have developed a printing filament that has a nano-copper additive within the filament the gives it

antibacterial properties (Copper 3D, 2018). These qualities are highly desirable for production of medical

components (Perez, et al., 2012; Flynn, et al., 2016).

Patient Specific Consumables

Long space missions under microgravity will have implications on human structural systems such as bones

and muscles. The ability to 3D print patient specific casts and body support may be of benefit for crew

suffering from these conditions. There is commercial terrestrial examples such as Activarmor (figure 21)

and orthopedic corset by Wasp (Buscaroli, 2018).

Figure 21: Example of patient specific 3D printed consumables (Activarmor, 2019).

With advanced capabilities for larger prints, other space oriented wearable medical devices such as

printed contraptions to regulate blood flow from limbs to upper body in order to mitigate the adverse

effects of microgravity can be considered. Printed personal body radiation shields may also be a future

application of such technology. The casting requires scanning and specific design which can be done prior

to the mission with CAD files stored or sent in case of an emergency.

Printing for Training Space Medical Crew

Crew level of expertise in medical operations is not high. To date, a medical surgeon is not an integral part

of space mission’s team and that may not change. With 3D printing technologies, it is possible to print

surgical aids to help a crew member perform a medical surgery that they are unfamiliar with. An example

of this would be for a dental procedure. If a crew member’s dental map was stored, a dentist on Earth

could upload a CAD model with the exact spot to drill that crew members teeth. This would then be 3D

printed, and used for the medical procedure. 3D printing of physiological models for training is very

developed and is offered by commercial companies such as Stratasys and Materialise (Materialise, 2019)

and demonstrated by operating hospitals (O’Neal, 2016).


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Figure 22: 3D printed heart model by Stratasys (Model of patient's left atrial appendage, n.d.).

Metal Consumables

Much like plastic consumables, steel consumables are also part of the medical kits onboard the ISS and

future exploration missions vehicles. However, metallic medical instruments constitute a lower

percentage of the medical kits in terms of both mass and volume. As such, developing a metal printing

technology for space mission may not be worthwhile. If such capability will exist, metallic medical

consumables could also be printed for the benefit of the medical services onboard.

As with the plastic consumables, simple common metallic tools will not be produced terrestrially by 3D

printing processes but rather by more efficient high-volume traditional methods that require larger

infrastructure. Terrestrially 3D technologies are reserved for high-end/cutting-edge medical procedures.

In space 3D printing technology can be utilized for simpler objects just to save the space and cost required

to send it from Earth.

For example, on Earth GE produced a special stainless steel tool to assist in hip joint replacement. This

tool is patient-specific 3D printed using Direct Metal Laser Melting (DMLM) technology (see Table 12

above for DMLM properties) (GE Additive, 2018a).


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Figure 23: 3D printed hip joint replacement tool by GE (GE Additive, 2018b).

This technology on Earth is expensive and required for very specific needs but in space if available can be

used in many other applications as well as printing simple metallic medical and surgical tools.

Figure 24: Metal 3D printed automatic suturing tool from Sutrue (3D printed suturing tool, n.d.).

Future exploration missions may require this capability of manufacturing for simpler tools such as

tweezers, surgical blades, needles and other special tools requiring metallic properties.

2.5 Mental Health

The presence of humans in space brings with it a number of unique risks in comparison to those on Earth.

These space-specific challenges all represent threats to the completion of mission goals. This would be

significantly amplified by undertaking deep space missions where mission time, mission importance and

physical dangers would be higher than any previously attempted. This section aims to provide an overview

of one specific risk to mission success: Human Psychology.

Deep space exploration, a currently untested expedition type, has been classified as high risk to mental

health (NASA, 2016a). The presence of unknown mission parameters implies that psychiatric and

psychological developments could become significant hazards (NASA, 2016a). Current data on this subject


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comes from two areas: analog on-Earth studies and in space human behavior research. Both sources shall

be further discussed.

2.5.1 Requirements

The psychology of being in space is a relatively young subject (Harrison and Fiedler, 2011). This began with

concern of how intercultural and interpersonal stressors could impact on an Astronauts’ cognitive capacity

to complete their work (Harrison and Fiedler, 2011). Even now, when working in a multicultural

environment is increasingly commonplace, electroencephalogram (EEG) studies of analog mission

participants found increased subconscious anxiety in regards to images of participants from other socio-

cultural groups (Bubeev and Ushakov, 2010). Significant decreases in emotional wellbeing and

interpersonal relationships have been positively correlated with space stressors in both Russian space

flights and analog missions (Manzey, Schiewe and Fassbender, 1995). Further to this, a lack of participant

or crew cohesion has been directly correlated with increased human errors (Landon, Vessey and Barrett,

2016). Terrestrial based research has consistently supported the concept that increased psychological

stress is detrimental to human cognitive skills (De la Torre, et al., 2010). Even mild levels of psychological

symptomatology (sub-clinical) could impact on individual health, team cohesiveness and task

performance levels (NASA, 2016a).

As stated, high risk actions, such as Extra Vehicle Activities (EVAs), have a high cost if unsuccessful - a small

error on Earth could mean death in space (Bishop, 2011). The ISS provides a good platform to understand

the impact of living in space on astronauts. The astronaut experience can be characterized by high levels

of monotonous work in a multicultural environment with significant penalties for error (up to and

including death) (NASA, 2016a). The proposed Deep Space Mission would include all these elements with

the additional risk of distance from rescue. No psychological emergency has occurred in space as of yet,

suggesting a validity to current approaches - however, it is unknown as to the transferability of these

techniques to different mission objectives, types, and crews (NASA, 2016b). Outcomes of distress in

extreme environment living situations appear to be dictated by the interactions of the physical

environment being experienced, the social context and individual personality types (Bishop, 2011).

Human factors research, such as discussed here, has developed a strong base of evidence to support the

hypothesis that decreasing levels of psychological and/or physiological stress, while simultaneously

increasing validated support techniques, will allow humans in space to work for longer with greater levels

of success (Landon, Vessey and Barrett, 2016). The importance of psychological support has been

identified as a significant variable requiring risk mitigation. This is for the protection of both the humans

involved in a space based mission as well as for the mission itself.

2.5.2 Technology

Two micro-mitigation plans shall be proposed in the following section in support of the mental health

needs of a crewed deep space exploration mission. These are:

1. 3D printing of recreational models and pieces to enhance crew leisure time options;

2. 3D printing of room dividers to allow astronauts autonomy of environment and enhanced privacy

options.


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Agencies provide psychological resilience training to provide the skill base to allow self-care in supporting

psychological wellbeing (Manzey, Schiewe and Fassbender, 1995). Personal and social resources are

essential predictors of well-being (Beutel, et al., 2010). Support is provided preflight, during flight, and

post flight to this end (Harrison and Fiedler, 2011). Complimentary to this plan, the 3D printing of items

available on Earth, such as games, could be used to enhance the recreational and social options of crew

and thus decrease the risks of monotony of routine. A cursory search of design databases identified over

100 available game designs, free to download (Yeggi, 2019).

An offshoot of the creation of recreational models could be the use of in-situ printers to create 3D models

of loved ones. This technology is currently available in terrestrial markets (Watkin, 2017). On a three year

mission, a crew member’s connection with loved ones on Earth would be very abstract, utilizing email and

video conferencing. The distance of important relationships could become extremely distressing. Crew,

for example, may be forced to watch their child's birth and adolescence via a computer monitor. The

ability to create models of their child throughout this time period could allow crew members to create a

more tangible connection to what they are missing. This may not lessen the distress of missing their

families but it may help make this distress more manageable. Tactile models of other items from home

may also provide a calming support technique for homesickness, such as models of home towns or

countries. This concept has never been tested in space.

Another potential support plan for the mission in question could be the use of the design of the habitat

used. Living and relying on a space station or shuttle is, by its nature, to give up a certain level of autonomy

inherent to living on Earth. Humans are constrained by the size and layout of the habitat area, reliance on

life systems and the pressures of crew size on available space (Imhof, 2003). Input from crew have

indicated areas requiring development in a design context to create a more human friendly habitat. For

example, those who worked on the Mir station requested a reduction in background noise levels (Imhof,

2003). The aforementioned areas of note on Earth would generally be considered basic tenets of

wellbeing, suggesting that unless adequately addressed in orbit, manufacturing facilities may struggle

with worker retention.

“Owning a location” appears to be an unspoken wish for those humans utilizing space habitats. Imhof

(2003) speculated that a sectioned, recreation specific area may be of use in supporting this. This allows

individuals to close the door behind them creating their own private area, separate from station work.

The ability to 3D print panels and dividers that could then be recycled would allow crew an autonomy and

variability of environment never seen in space habitats.

Those products can be created utilizing additive printing techniques currently available and used both on

Earth and in orbit thanks to the 3DP demo printer (refer to Section 3.1 in Chapter 1). Design plans for

generic forms of both product types are currently available for free on multiple platforms with multiple

successful uses (Grunewald, 2016; Yeggi, 2019). While the necessary printer has been tested in orbit,

neither product type has been printed in orbit and thus requires in-situ testing for qualification.


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The elimination of psychological stressors in this mission type is not possible. However, the

aforementioned approaches of bringing “Earth to Space”, may allow micro mitigations to be utilized to

create an impact that is significant in its totality. The aim of this mitigation being the promotion of crew

wellbeing and thus the promotion of mission objectives.

2.6 Radiation (Crew)

2.6.1 Requirements

Radiation continues to pose an enormous risk to agencies considering long-term crewed missions outside

of the Earth’s magnetosphere. While terrestrial levels of radiation are relatively low, solar and galactic

radiation stretches across our solar system, making deep space travel extremely dangerous for humans.

The sun provides the majority of the damaging radiation in our solar system - however, galactic cosmic

radiation (GCR) is also present stemming from radiation within the Milky Way galaxy (Rask, et al., 2008).

The two primary types of radiation are ionizing and non-ionizing. Both radiation types cause critical

damage. However, non-ionizing radiation can be shielded against due to its relatively long wavelength

and lower energy. Ionizing radiation is primarily responsible for the conundrum space agencies face in

crewed space flight. Ionizing radiation is composed of high energy particles or photons capable of

removing electrons from atoms or molecules (Rask, et al., 2008). Ionizing radiation can be categorized

into 3 primary groups depending on its source:

1. Trapped radiation belt particles (Van Allen)

2. Cosmic rays

3. Solar particles (Rask, et al., 2008)

While most people on Earth are protected from these various types of radiation, astronauts are highly

exposed and largely unprotected.

There are three critical factors that dictate how much radiation an astronaut receives: solar cycles, altitude

from Earth (distance from the magnetosphere), and the individual’s susceptibility (Rask, et al., 2008). The

sun solar cycle is roughly 11-year which helps astronomers and scientists predict the severity, number of

solar spots, and coronal mass ejections responsible for detrimental radiation throughout our solar system

(Rask, et al., 2008). In addition, each individual is more or less susceptible to radiation similar to how some

families have a higher likelihood for certain types of cancer due to their genetic predispositions. Finally,

altitude dictates an astronaut's protection from this harmful radiation. The Earth’s magnetic field blocks

the majority of this radiation. However, astronauts on the ISS, at an altitude of 350-400 km, are exposed

to approximately 40 times the amount of radiation people are exposed to on Earth’s surface within a

single year (Rask, et al., 2008).

As can be seen in Table 13, age and gender also dictate the standard astronaut career exposure limits.

This is primarily due to the risk of various types of cancer associated with gender and age. To compare,

terrestrial humans are only exposed to .0036 Sieverts (Sv) per year (Rask, et al., 2008).


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Table 13: Career astronaut limits for males and females at varying age (Rask, et al., 2008).

Career Exposure Limits for NASA Astronauts by Age and Gender

Age (years) 25 35 45 55

Male (Sv) 1.50 2.50 3.25 4.00

Female (Sv) 1.00 1.75 2.50 3.00

On the ISS, radiation is measured through either passive or active dosimeters. These devices are capable

of measuring the astronaut's dose equivalent which is a standardized radiation measurement metric

taking into account the different types of ionizing radiation that can induce biological damage (Naef,

2018).

Mission types have been categorized to compare expected radiation exposure levels shown in Table 14.

Having selected a 3-year mission, Mars exposure estimates will most likely be synonymous with this

mission type. With no improvements in technology, this exposure is over 100 times the yearly radiation

exposure on Earth and excludes 25-year-old women from participating in the mission. Clearly, there is a

need for better radiation protection to reduce the risks posed in a long-term mission.

Table 14: Mission specific radiation doses (Rask, et al., 2008).

Mission Type Radiation Dose (mSv)

Space Shuttle Mission 41-C (8-day mission orbiting the Earth at 460 km) 5.59

Apollo 14 (9-day mission to the Moon) 11.4

Skylab 4 (87-day mission orbiting the Earth at 473 km) 178

ISS Mission (up to 6 months orbiting Earth at 353 km) 160

Estimated Mars mission (3 years) 1,200

Currently, the primary method of radiation protection on the ISS is through structural shielding. The

structure is composed of 1 cm thick aluminum. Certain areas contain additional shielding, with a blanket

just inside the aluminum structure containing six layers of Kevlar and six layers of Nextel (National

Research Council, 1997). Additional methods and materials for protection are under investigation at

various space agencies in preparation for longer missions outside at the limits of Earth’s magnetosphere.


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Some of these materials, such as polyethylene, have to ability to be 3D printed to maintain adaptability

during missions.

2.6.2 Technology

Radiation exposure for astronauts poses a significant technology gap for crewed deep space exploration.

Various technologies are currently under development to mitigate the risk to astronauts. However, in

Section 2.6.1 of this Chapter, it was shown that a 3-year mission to deep space would increase the typical

yearly exposure limit derived from the ISS from 150 mSv to 1,200 mSv (Rask, et al., 2008). There are many

mitigation strategies including improved radiation shielding, pharmaceuticals, diet, and personalized

plans. This section will focus on primary radiation shielding for the spacecraft and secondary radiation

shielding techniques to optimize the radiation exposure an astronaut is subjected to.

To create reasonable expectations in technological advancements prior to a 3-year duration crewed

mission, the maximum exposure limit will be maintained at approximately 150 mSv. This value is backed

by significant research and ISS participants are not readily eager to relax this baseline. However, based on

the various 1-year missions on the ISS, such as astronaut Scott Kelly’s, research may prove that exposure

to 320 mSv may be within reason. The 320 mSv value is an extrapolation from current ISS 6-month mission

data. That said, there are various approaches to shielding that will assist in simplifying the overall

spacecraft design. The following shielding schemes have been identified by NASA as areas in the

spacecraft that would benefit from increased shielding efforts (Clowdsley and Simon, 2013):

1. Personalized Shielding;

2. Individual Crew Quarter Shielding;

3. Crew Quarter Shielding;

4. Entire Spacecraft Shielding.

This appears a very logical technique to mitigating the risk of astronaut exposure. Astronauts sleep on

average 7-8 hours on the ISS and spend another 2-4 hours per day in crew quarters talking with family

members, crew members, or eating meals (Rovera, 2014). This means that astronauts spend

approximately half their day in one contained area. Increased radiation shielding in these areas will

significantly aid in protections from Galactic Cosmic Radiation (GCR) and solar radiation.

One of the current barriers to improving radiation shielding is the mass associated with developing an

adequate shielding technology. To put this in perspective; it would take well over 60 heavy lift launches,

each capable of carrying 40.5 tonnes of aluminum, to meet the radiation shielding baseline set by the ISS

at 150 mSv (Singleterry, 2013). This is highlighted by Figure 25 along with other potential materials under

consideration.


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Figure 25: Effectiveness of different radiation protection materials vs. launch mass (Singleterry, 2013).

Based on Figure 25, aluminum and multi-layer insulation (MLI) are not feasible to use as the primary

method of radiation shielding throughout the entire spacecraft. The following lists the primary methods

proposed for long duration deep space missions based on research being undertaken by various space

agencies (Singleterry, 2013):

1. High-density liquid hydrogen wall;

2. Liquid hydrogen wall;

3. Water wall;

4. High density polyethylene;

5. Aluminum + MLI;

6. Active radiation shielding.

Active radiation shielding, such as magnetic field generation from the spacecraft, will be excluded from

this report due to its low TRL and high power demands. Liquid walls are one of the primary suggestions

for radiation shielding improvements and Figure 26 shows a very basic design for how this technique

would work within a spacecraft for cryogenic liquid hydrogen. The open pocket in the middle of the

diagram titled ‘Crew Quarters’ is the daily operating area for the astronauts while the 2 gray circles depict

aluminum shielding encapsulating the liquid highlighted in green.


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Figure 26: Simple hydrogen shielding design.

Cryogenic hydrogen and water walls have more effectively shielded against the high ionizing energy

particles emitted by the sun or elsewhere in the solar system (Singleterry, 2013). Polyethylene also

provides an interesting solution and can be utilized in tandem within the MLI for typical shielding systems.

Table 15 is a trade-off study of the various techniques and some key parameters associated with radiation

shielding.

Table 15: Trade-off to provide advantages and disadvantages of various shielding methods (Singleterry,

2013).

Shielding Method Density Effectiveness

with Equivalent

Mass

Material

Handling Danger

Secondary Use

Liquid Hydrogen Wall Low High High Fuel

Polyethylene Medium Medium Low N/A

Water Wall

Medium Medium Low Closed loop water system for onboard

support

Aluminum with MLI High Low Low N/A

Based on the trade-off study, it was concluded that liquid hydrogen is the most effective and useful

radiation shield. Cryogenic hydrogen poses a large risk to the crew due to its combustion characteristics

so the engineering solution will need an extremely cautious approach to ensure unnecessary danger is

not introduced to the crew. However, it is also acknowledged that a combination of methods are needed

in order to properly shield the crew from hazardous radiation.

Liquid hydrogen and liquid water shields support the sustainable spacecraft objective by having alternate

uses such as fuel and the closed loop water reclaiming system. The fuel can be used for emergency

maneuvers or planetary lander capabilities while the water can be used at the final destination for bio-

regenerative systems.


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The final recommendation for radiation shielding are shown in Table 16.

Table 16: Recommendations for radiation shielding in spacecraft.

Compartment Type Shielding Method

Personalization Polyethylene stitching in crew clothing

Individual Crew Quarter Water bladder sleeping bags, pharmaceuticals, and dietary restrictions

Crew Quarters Common Area High density cryogenic liquid hydrogen wall

Spacecraft Repair Aluminum shell with MLI layered with polyethylene. Repair if radiation shielding is damaged in transit.

Additive manufacturing plays a larger role for the personalization and repair. The suggestion in Table 16

supports specialized crew clothing with integrated polyethylene structures and, more importantly,

increased shielding around the most susceptible organs. Stratasys is an industry leader in terrestrial

printing and has begun to work with fashion designers to design and print specialized clothing and

wearables (Swack, 2016). This is a very underdeveloped field terrestrially and space agencies will have to

drive advancements to implement solutions involving additive manufacturing clothing and wearables.

However, this technology would help customize the way space agencies react to radiation threats.

Repair operations will also be heavily supported by additive manufacturing. If there is damage during

transit to the radiation shielding, SLS or FDM printers can be utilized to print aluminum or polyethylene

to help repair and bolster the radiation shielding. The Refabricator and the MAMBA are good candidates

to recycle and reprint parts for radiation shielding due to their recycling ability as discussed in Chapter 1,

Section 3.1. The HMC system discussed in Section 2.2.2 of this Chapter can be utilized to create radiation

shielding tiles using a closed loop system. The ability to adapt and react to unforeseen situations remains

the greatest advantage of additive manufacturing and holds true for radiation shielding. 3D printing of

pharmaceuticals for radiation protection is further discussed in Section 2.3 of Chapter 2.

The plethora of suggestions shown in Table 16 improve on today’s baseline, but there is still a substantial

gap in meeting the 150 mSv goal. The radiation limit may need to be relaxed for a 3-year mission to

become more feasible and experiments on the ISS will need to be conducted to quantify and verify the

suggested recommendations.


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3 Technical Factors

The previous section discussed the human requirements as well as the ISM technologies that can

efficiently and sustainably address those requirements. Similarly, the below section discusses the

technical requirements from a spacecraft perspective as well as the ISM technologies that can address

those requirements.

3.1 Radiation

3.1.1 Requirements

The spacecraft will pass through many varied radiation profiles on its journey and must be adequately

prepared for all of them. There is the thick, dense, low-energy plasma of LEO (Schrijver and Siscoe, 2012),

the highly charged particles of the Van Allen belts, and the energetic plasma and cosmic radiation beyond

the reach of Earth’s magnetosphere (Barth, 1996). Each event can have a variety of deleterious effects on

spacecraft subsystems, and so each must be prepared for and mitigated.

The low energy plasma found in LEO leads to spacecraft charging. This effect is intensified by the higher

energy plasma and charged ions found in GEO and beyond, with possible floating voltages of several

thousand volts during a solar storm. An electric charge building up across the surface of the spacecraft is,

to some extent, unavoidable. If any parts of the spacecraft exterior are electrically isolated from the rest,

this can lead to arcing, damaging the spacecraft in the process (Schrijver and Siscoe, 2012).

Although short missions may only gain a floating surface voltage of around 0.5V, multi-year missions can

build up much higher charges; 10,000V has been observed in rare cases. The ISS can have a floating

potential of up to -140V. Although this is thankfully too low to cause arcing between the station and

resupply shuttles, it does cause other issues – the thin anodized coating on the outside is gradually

stripped away by the difference between this float and the charge on the outside of the coating, which

does sometimes lead to arcing (Schrijver and Siscoe, 2012). Additionally, if the wires between solar cells

collect a charge, the potential difference across the solar array can be affected and the current produced

can drop drastically. To counter this, the floating voltage is reduced by a Plasma Contactor – a device that

charges Xenon gas and ejects it to reduce the floating voltage (Patterson, et al., 1994).

Solar arrays are also particularly vulnerable to total dose effects of radiation over time, leading to

degradation effects and a loss of efficiency (Figure 27). For long missions a significant degree of over-

engineering is required to allow for sufficient power generation at all stages. The same occurs with many

other electronic subsystems in a spacecraft – after biological tissue, electronics are the most vulnerable

components to radiation-induced degradation (Schrijver and Siscoe, 2012).


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Figure 27: Solar Cell Power Loss vs Radiation (700 km altitude, 30° inclination) (Schrijver and Siscoe,

2012).

Sensitive semiconductor electronics are also at risk of Single Event Effects (SEEs). A particle with an energy

of the order of GeV can penetrate an electrical system and have a number of effects. The simplest is a

single-event upset, where a bit is simply flipped from 0 to 1. This can be corrected for with simple error

checking by software. Other effects, however, can include a latch up, causing an electrical feedback loop

across a semiconductor junction until it is powered off, or rupturing the insulating layer and rendering the

gate useless. The lower the voltage of a subsystem, and the smaller it is, the more vulnerable it is to these

effects, causing problems for any spacecraft designer concerned with their mass and power budgets

(Schrijver and Siscoe, 2012).

One potential solution to these issues is to 3D print replacement electronics and solar arrays as needed,

as well as printing additional radiation shielding and electrical contacts for repair purposes.

3.1.2 Technology

Different shielding techniques have already been covered in depth in Section 2.6 of Chapter 2. Apart from

the possible use of recycled waste printed into radiation shielding discussed in Section 2.2 of Chapter 2,

3D printing could be used to replace damaged or non-functional electronic components, saving space and

producing highly customizable circuitry on demand.

3D printing of electronics has been researched under terrestrial conditions – Optomec has successfully

printed electronics onto substrates, both 2D and 3D. Using a method called Aerosol Jet printing, a

conductive material can be aerosolized and sprayed onto a film in lines as thin as 10μm, and is able to

print resistors, capacitors, sensors, antennas, and transistors. Use of a dielectric can also produce the

effect of a multi-layer circuit board, allowing for complex circuitry to be produced on very thin, lightweight

film (Optomec, 2018a). nScrypt have developed the Factory in a Tool (FIT) platform for the US military,

which is capable of using a wide range of materials and substrates to print a variety of things – circuitry


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included (Vialva, 2018b). Both have been proven on Earth, although they have yet to undergo flight testing

of any kind. These various 3D printing techniques address the highest failure rate currently witnessed on

the ISS, as shown in Figure 3 in Chapter 1, Section 1.

The printing of solar panels is also difficult to achieve, but has also been proven in terrestrial

environments. Optomec has used their Aerosol Jet printing technique to print solar cells (Optomec,

2018b), and research by the Victorian Organic Solar Cell Consortium has produced films of solar cells

printed on organic material (O'Neil, 2014). The circuitry of the array can be printed with the electronic

circuitry methods listed above, with large metal printing and structural assembly being used for the

structure of the array. This could make use of Made in Space’s Archinaut, or a similar system discussed in

Section 4 of Chapter 1. Assembly can be completed manually by crew members, but automated assembly

of electronic components has already been flight-tested by Made In Space, with the Satellite

Manufacturing Machine (SMM) assembling and linking several electronic components under microgravity

conditions during a parabolic flight (Made in Space, 2017).

3.2 Communication

The ability to communicate and exchange information with a spacecraft is critical to ensure its normal

mission operations and long-term survivability. The section below discusses the requirements of a deep

space mission in terms of communication as well as the ISM technologies that can be leveraged to address

those requirements.

3.2.1 Requirements

A crewed mission on a three year journey into deep space will require featuring sufficiently reliable and

efficient communication systems and interfaces to ensure the maximum possible throughput is achieved.

As electromagnetic waves propagate in free space, their energy is spread across an increasing volume of

space. The ratio of the available power at a receiving antenna and the power of a transmitting antenna

can be given by the below formula, derived from Friis’ equation (Shaw, 2013).

𝑃𝑟

𝑃𝑡 = (

𝜆

4𝜋𝑅)2𝐺𝑟𝐺𝑡

Where the below assumptions and definitions apply:

– Free-Space Path Loss (FSPL) is given by (4𝜋𝑅

𝜆)2 , or 20𝑙𝑜𝑔(

4𝜋𝑅

𝜆) 𝑑𝐵 ;

– R >> 𝜆 such that both antennas are in the far field of each other;

– Pt is the power delivered to the terminals of an isotropic transmit antenna (in Watts);

– Pr is the available power at the receiving antenna terminals equal to the product of the power;

density of the incident wave and the effective aperture area of the receiving antenna

proportional to 𝜆 2 (in Watts);

– Gt is the transmitting antenna gain;

– Gr is the receiving antenna gain;

– The antennas are correctly aligned and have the same polarization;

– The antennas are in unobstructed free space, with no multipath;


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– The bandwidth is narrow enough that a single value for the wavelength can be assumed.

Based on the above equation, the available power at the receiving antenna (Pr) is inversely proportional

to the distance between the two antennas (R). As such, the further a spacecraft travels into deep space,

the less power its antenna can receive and the more power it needs to send data, thus limiting the data

rate that can be transmitted. This can also be characterized by an increase in the Free-Space Path Loss

(FSPL) as the distance between the two antennas increases.

In addition, although higher frequencies (i.e., shorter wavelength) can transmit more data than lower

frequencies within the same amount of time, higher frequencies experience a higher FSPL than lower

frequencies. An example of the challenges in this area can be attested by the eccentricity of Mars’ orbit

causing the distance between Earth and Mars to vary tremendously, from a minimum distance of 55

million km to a maximum distance of 400 million km at superior conjunction (Ho, Golshan and Kliore,

2002). As such, the FSPL between Earth and Mars is much higher than FSPL between Earth and GEO

satellites for example, while it also varies depending on the relative positions of Earth and Mars.

Table 17 below shows the FSPL between Earth and Mars for various frequencies ranging from 300 MHz to

32 GHz.

Table 17: Free-Space Path Loss at Various Frequencies (adapted from Ho, Golshan and Kliore, 2002).

Distance (km)

Free-Space Path Loss (in dB)

VHF Band (300 MHz)

S Band (3 GHz)

X Band (10 GHz)

Ka-Band (32 GHz)

Optical (~300 THz)

Earth-ISS 400 ~134 ~154 ~165 ~175 ~254

Earth-GEO 36,000 ~173 ~193 ~204 ~214 ~293

Earth- Mars at Opposition

55 x 106 ~237 ~257 ~267 ~277 ~357

Earth-Mars at Conjunction

400 x 106 ~254 ~274 ~284 ~294 ~374

Additionally, future missions are expected to become more complex and require more data to be

transmitted between the spacecraft and the ground station, as showcased by NASA’s Deep Space Network

forecast below (Figure 28). To achieve data rates 10 to 100 times higher than state-of-the-art present

radio frequency communications, NASA is investing in optical communications, where data is transmitted

using frequencies falling close to the visible part of the spectrum (Campbell, 2017).


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Figure 28: NASA Deep Space Network Capabilities (Hughes, 2017).

One way to mitigate the power losses in free space is to increase the antennas’ gains (Gr and Gt). Figure

29 below illustrates an example where an antenna’s gain is increased by enlarging the antenna. This can

be made by adding antenna elements such as in array antennas and thus adding gain. Directly 3D printing

these radiating elements can improve the antenna gain in case of no other available option. (Satmarin,

2019). Albeit the possibility of increasing an antenna gain by augmenting its diameter is feasible, three

issues affect the design of antennas for spacecrafts; (i) size restrictions due to fairing dimensions of launch

vehicle, (ii) vibrations and other mechanical loads during launch, and (iii) antennas exhibit a logarithmic

relationship between gain and diameter (i.e., as illustrated in Figure 29, increasing the antenna size by a

factor of 8, increases the gain by a factor of 1.6 only).

Figure 29: Relationship between Performance and Antenna Size (Satmarin, 2019).


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The section below will assess the potential to use a 3D printer coupled with assembly robotic arms that

will enable the manufacturing of large antennas and reflectors for optimized deep space communications.

3.2.2 Technology

This section addresses the communication hurdles discussed in the above section and discusses the

feasibility of using a 3D printing technology coupled with assembly robotic arms to improve

communication between a crewed spacecraft in deep space and Earth. Such technologies are currently

being developed by Made in Space with the Archinaut and by Tethers Unlimited with the SpiderFab.

Additionally, Kleos Space and Magna Parva are investing in manufacturing techniques of carbon fiber

structures to create antennas and solar panel arrays (Kleos, 2019).

As mentioned in Section 4 of Chapter 1, Made in Space is making progress on its Archinaut technology,

which will enable the in-orbit manufacturing and 3D printing of antennas, reflectors, radars, arrays and

other structures for direct use in space. The two projects which employ the Archinaut technology are

underway; the first 3D printing and in-orbit manufacturing is Dilo, a spacecraft that transforms into a large

reflector, while the second is Ulisses, a free-flying robot that manufactures and assembles large structures

in space (Made in Space, 2018). In 2017, Made In Space was able to demonstrate its Archinaut technology

in a thermal vacuum chamber at NASA Ames Research Center by printing a 32m long beam (Wall, 2017).

Dilo could bring in added-value to a crewed deep space mission. In fact, the reflective elements are stored

on-board and only attached to the Dilo itself through 3D printing techniques to create a fully deployed

large reflector (Figure 30), thus greatly reducing the required launcher size and dimensions (Made in

Space, 2018). As mentioned previously, an increase in the antenna size can mitigate the power losses

associated with the free-space path loss.

Figure 30: Archinaut Dilo Spacecraft Attaching its Reflectors (Made in Space, 2018).

Additionally, Harris Corporation, a company specializing in communication systems for the space and

defense sector, developed a 3D printing technique that uses titanium to manufacture Fixed-Mesh

Reflectors for communication satellites such as one of the Inmarsat’s satellites. Using 3D printing

technology, Harris was able to eliminate 3.5 hours of labor production time and reduced assembly errors

(Harris, 2016).


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Such aforementioned improvements in 3D printing and assembly technologies could be merged into a

single solution. The initial phase will require Fixed-Mesh Reflectors to be 3D printed on-board the crewed

spacecraft to Mars. This phase will be followed by a second phase that leverages the Archinaut’s

technology to attach and assemble those 3D printed reflectors directly in orbit. As such, a crewed deep

space mission will likely benefit from acquiring deep space communication capabilities provided by Dilo.

Other antenna components can also be 3D printed on-board (i.e., customized horn antennas and antenna

arrays) by using Swissto12’s technology currently being used for manufacturing of Earth antennas

(Swissto12, 2019). Combining the Archinaut technology with Swissto12’s 3D printing can bring in added-

value. Eventually, research and development to manufacture such antenna horns and arrays directly in

space could enable cost saving in the form of reduced spare component storage requirements, while

enabling a higher reliability of communication systems on a spacecraft.

To reduce risk and increase reliability, a redundant communication system will need to be on-board the

spacecraft with ability to 3D print replacement parts for Dilo. Risks associated with integrating and not

integrating such technologies on-board will be further addressed in Section 7.


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4 Spacecraft Parameters

4.1 Storage Space

As the duration of crewed missions increases, demand for critical life components and spare storage will

increase accordingly. Currently, the Russian modules Rassvet and Zarya and the Italian module Leonardo

MPLM are used for storage on the ISS, with a combined volume of just over 55m3 (International Space

Station, 2019). A long-term deep space mission may not have the luxury of this storage space - mass

considerations could be expected to restrict the size of the spacecraft, and resupply from earth would be

nearly impossible. Along with mass, a saving in storage space would be a major benefit ISM could provide,

due to the ability to print on demand from a common feedstock rather than keep spares of multiple

distinct parts. Storing liquid or powder bulk material will always be more efficient in space than storing

the final products which require special packaging and have specific form and volume.

4.2 Mass

One of the greatest barriers to space exploration is launch cost. Launch cost is directly influenced by mass,

so any reduction in mass will reduce the cost of a space mission. One way to achieve this is to reduce the

mass of spare items taken into orbit by means of additive manufacturing. Owens, et al., (2015) describes

how additive manufacturing is able to reduce this mass by, “enabling commonality of material”. The

authors quantify the mass of spares and the probability of part failure in order to determine how many

times a part will need to be replaced or repaired. They also take into account how much spare weight is

carried by those parts that were never replaced and carried over to the next mission. They used these

numbers to determine the amount of feedstock required for long duration missions as well as the mass

reduction that this can provide.

In a case study on a hypothetical twenty-six month deep space mission, replacing ECLS components, it

was determined that the spares mass reduction was at 17% using low precision manufacturing (Owens,

et al., 2015). By using high precision manufacturing, the mass was reduced by 35%. A summary of the

baseline and mass savings can be found in table 18 below.

Table 18: Mass of spares and reduction by using AM on a twenty-six month deep space mission (Owens,

et al., 2015).

Manufacturing Precision

Baseline Mass (t)

Total Mass for Spares with AM (t)

Total Mass for Feedstock (kg)

Reduction in Mass (%)

Low 9.21 7.65 642 17%

High 9.21 6.02 909 35%

For subsequent missions beyond the initial flight, the mass required for spares is less, as is the savings

using additive manufacturing. The reduction of mass for the second flight is 6.7% for low precision and

13.3% for high precision manufacturing. There is a reduction of mass up to the 9th mission, where savings

taper off. These results were based on bringing all spares and feedstock from Earth. When calculating


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using in-situ resource feedstock, such as from the surface of Mars, the mass savings are increased to 2.20t

- a 41% increase in savings over earth based feedstock for low precision manufacturing. For high precision

manufacturing with ISRU feedstock, there was a 4.10t mass savings resulting in a 29% increase in mass

savings over earth based feedstock (Owens, et al., 2015). The mass saving graphs from the cumulative

spares and spare logistics with Earth based and ISRU based feedstock can be seen in figure 31 below.

Figure 31: Mass savings from AM using Earth based and ISRU feedstock (Owens, et al., 2015).

In a comparative analogy, Owens and de Weck (2016) showed that the number of spares in orbit on the

ISS is currently over 13,000 kg. The expected average of failures was reported to be only around 450 kg

annually (see Figure 4 of Section 1.1). Added to this mass is the estimate of spares on the ground of about

18,000 kg that are ready to fly at any given time. Out of the approximate 31,000 kg in spares, it is estimated

that 95% will most likely never be used. However, as these are mission critical spares, they must be in

circulation and ready to fly or to be manufactured. 3D printing is a technology adequate for producing

spares on demand reducing mass and storage volumes. If only 450 kg of spares are used out of 13,000kg,

that leaves 12,000 kg for the weight of the printers itself and 5% margin for bulk material. Additive

manufacturing and recycling create a suitable solution for spare parts and specialization while in transit.


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5 TRL Timeline

Figure 32, below, gives an overview of the different Technology Readiness Level (TRL) levels and how they

equate to where a technology is in its development lifecycle. To get an idea of the TRLs of the technologies

discussed in chapter 2 thus far, they have been outlined below in Table 19. This shows the mission

requirements, ISM technologies, and applications of each technology, as well as the TRL based on current

research and development.

Figure 32: An explanation of TRL levels (WaybackMachine, 2004).


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Table 19: Technology Readiness Levels of discussed ISM technologies.

Requirement Chapter/Section Discussed Technology Technology Status TRL

Heat Melt Compactor (HMC)

2.2: Waste Management Water extraction/ structural component build

Developed (terrestrial) 7

Environment dividers

2.4: Mental Health Additive printer (Made in Space 3DP)

Printer viability demonstrated on ISS. Product developed terrestrially.

9

Recreational models and pieces

2.4: Mental Health Additive printer (made in space 3DP)

Printer viability demonstrated on ISS. Product developed terrestrially.

9

Refabricator 1, 3.1: Current Techniques 2.2: Waste Management

Integrated plastic recycling and plastic printing

Printer viability demonstrated on the ISS.

8

Air Revitalization system

2.1.2: Atmosphere Recycle carbon dioxide into oxygen

Printer viability demonstrated on the ISS.

8

Water Recycling 2.1.2: Water

Waste water and air moisture recycling into clean water.

Part of ECLS in use on ISS 9

Metal Advance Manufacturing Bot-Assisted Assembly (MAMBA)

1, 3.2 - In-Development Techniques 2.2 - Waste Management

Integrated metal recycling and plastic printing

Component development prior to full assembly

4

3D printing of Medicine

2.3: Medical Supplies

Thermal Inkjet Printing/Fused Deposition Modelling (FDM)/ZipDose

Fully developed for terrestrial use. Delayed by regulation. Not yet developed for space application, uses conventional 3D printing technologies

5


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Communication Antenna Structure and Assembly

3.2: Communication Archinaut

Under development with vacuum thermal test successfully passed and in-space test expected in 2019

6

Communication Antenna Reflector

3.2: Communication

Harris’s 3D printed Fixed-Mesh Reflectors using Titanium powder

Technology developed on Earth but for use in Space

5

3D printing of electronic circuitry

3.1: Radiation (Equipment) Aerosol Jet (electronics) and FIT

Proven in terrestrial environment

5

3D printing of solar cells

3.1: Radiation (Equipment) Aerosol Jet (solar cells) and VICOSC

Proven in terrestrial environment

5

Automated assembly of components

3.1: Radiation (Equipment) Made In Space SMM

Tested on parabolic flight

6


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6 Challenges

While 3D printing could be revolutionary if applied to space products, it should not be seen as a global

solution as there are still multiple challenges to overcome before additive manufacturing can reach its

maximum potential.

Before getting into the details of the three main challenges identified, Table 20 shows a SWOT analysis of

3D printing based on the study developed throughout this report. The SWOT analysis has the advantage

of synthesizing the strengths and weaknesses of a defined topic with regard to the opportunities and

threats generated by its environment. Hence, this analysis is of particular importance to set the basis of

the challenges and limitations 3D printing can face.

Table 20: SWOT analysis of 3D printing (McAlister and Wood, 2014).

Strengths Weaknesses

- Reduced design constraints

- Reduced number of parts

- Efficient use of materials

- Reduced supply chain

- Negates dedicated tooling

- Reduced labor cost

- Less barriers to market

- Limited material variety

- Limited structural properties

- Cost

- Speed and volumes

- Usability

- Printer proliferation

- Design Issues

Opportunities Threats

- Customized products

- Cheap small production runs

- Physical testing

- Job creation

- Manufacturing repatriation

- End to obsolescence

- Drive to innovation

- Copyright, patents and ethics

- Tort law

- Frivolous printing

- Traditional job losses

- Qualification

- Manufacturing

That said, to take full benefit of the 3D printing and manufacturing capabilities the following key

challenges need to be addressed.

6.1 Design Challenges

The main challenge coming from the design is that current design tools are not capable of enabling the

full capacity of additive manufacturing. In fact, design tools do not include specific features for 3D printing

and they often are not compatible with the machine programs which leads current design tools that are

not adapted to facilitate additive manufacturing features (Ghidini, 2013).


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Additionally, 3D printers operating in space must be designed to take into consideration the launch

environment. As such, a 3D printer launched into space will experience vibration loads, mechanical

stresses, acoustic and thermal loads, and must thus be designed to resist those external stresses. When

operating in microgravity, 3D printers must be able to operate normally under microgravity constraints.

Hence, they should be fitted with active feedstock pumps or pushers for example.

Another challenge related with 3D printing technologies is the need for pre-processing as well as post-

processing operations. As such, 3D printed components must be removed from the printer, and polished

or ground to meet the desired surface finish, electrical conductivity, and look and feel in the case of

medical products for example.

One last challenge needs to be noted as its importance is not negligible: the design rules for 3D printing

are not fully established yet (Ghidini, 2013). In other words, if traditional design answers to specific

requirements, those are quite different when speaking of 3D printing, especially if this printing is done in

space. Table 21 demonstrates those design difficulties for the products discussed previously.

Table 21: ISM Design Challenges.

Products Design Challenges

Waste Management

Systems

Ensure that recycling input can come in a large variety of forms and

materials (including metals and electronics), not just pre-used plastic.

Include spare parts for the hardware itself since they might not be

manufacturable if hardware fails.

Bio-regenerative Systems High space requirements, high energy demands, complex biological

interactions, catastrophic failures leading to contamination.

Closed Loop Systems

Next generation life support system, which can recycle CO₂ into O₂,

has been installed in the US Destiny laboratory. The new system is

made to demonstrate the new technology. It can recycle more than

50% CO₂ exhaled by the astronauts. Higher efficiencies are harder to

reach, which currently results in significant mass loss in air over the

course of a long mission.

Radiation &

Micrometeoroids Shielding

Ensuring enough micrometeoroids shielding is provided around the

spacecraft to ensure that cryogenic hydrogen or water walls are not

penetrated. Need to ensure printers are able to print both a high level

of detail and large structures, depending on whether printing a full

solar array or sensitive microcircuitry. Polyethylene imposes design

challenges due to its operating temperatures for example


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Medical Supplies

Developing the design to work in microgravity. As the full capabilities

of the technology have not yet been matured to operate in

microgravity, the design of such a process will need much

consideration. Some of the current techniques are based on powder

or liquid bulk materials which under microgravity can behave

differently than expected on Earth. This can affect product quality but

also human health. Yet, the challenge is reduced by the fact the many

of the printing techniques are well established 3D printing techniques,

and specific solutions can be found.

Communication (Antennas

and Reflectors)

Design is constrained by the 3D printer size, which limits the volume

of products that can be manufactured.

Additionally, low mass material are usually favored on space missions

and will put constraints on the design of antenna and reflectors.

Mental Health Products

Generic designs are already freely available for the products in

question however adjustments may be required for in space usage

such as preventing free floating components which could create

hazards.

6.2 Manufacturing Challenges

Accuracy, reproducibility and reliability have to be guaranteed from raw material to the end product

through the manufacturing process. However, currently the raw material procurement is not fully

controlled which has an impact on the manufacture. For instance, the characteristics of the powder can

change from one furnisher to another, the traceability of the latter is difficult and the same applies for its

procurement.

Regarding the technical part of the 3D printers and their process stability, it has been demonstrated that

two identical machines from the same manufacturer produce slightly different output (Ghidini, 2013). This

could potentially create difficulties if two identical pieces are required or if one piece is of poorer quality.

Those manufacturing challenges are illustrated in Table 22.


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Table 22: ISM Manufacturing Challenges.

Products Manufacturing Challenges

Waste Management

Systems

Develop installation, testing, and maintenance techniques for the

hardware to account for mission duration; Confirm manufacturing times

and procedural list are both small enough to lower the risk of user

mistakes.

Bio-regenerative

Systems

Implementation from prototypes to large scale systems.

Closed Loop Systems

Ensure sufficient redundancy in all closed loops to minimize risk.

Address degradation of the plastic during the recycling process and ensure

process control. The integrity of the printing process relies on the

feedstock having stable chemical, mechanical, and geometric properties.

Medical Supplies

Sterilization of the equipment, in microgravity, it is extremely difficult to

maintain clean environments; High grade 3D printing machines especially

ones that are used for metals and electronics can be quite large and

require consideration in mass and volume budgets; Complete automation

of the process is not viable in the near future. Pre- and post-fabrication will

require human intervention; In some cases the medical treatment is an

emergency, the technology manufacturing time constants are not short

enough yet. Thus some supplies will have to be pre-made and not

manufactured on demand.

Communication

(Antennas and

Reflectors)

Ensuring correct alignment of antenna reflectors when positioned on the

structure (i.e. Dilo); Ensuring reflectors can be easily moved if not properly

aligned; 3D printing of metals in microgravity is still under-development.

Radiation &

Micrometeoroids

Shielding

There are large mass requirements to launch sufficient cryogenic liquid

hydrogen for shielding. The liquid hydrogen installation into the spacecraft

will also need to be handled carefully and may increase risk. Polyethylene

imposes certain manufacturing challenges regarding hazardous fumes and

thermal control needs.

Mental Health

Products

Utilizing terrestrial manufacturing information available for the designs in

question, manufacturing time can range from two hours twenty minutes

through to eight hours (Yeggi, 2019). This information must be prefaced

with a caveat however as they have, as of yet, not been tested in situ

microgravity tests. Challenges may be identified once this testing occurs.


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6.3 Qualification and Standardization Challenges

The main difficulty regarding the qualification and standardization of 3D printed products is that the

classical qualification methods do not apply for additive manufacturing because the material evaluation

samples are not always representative of the printed object, the polyamide (PA) requirements are not

established yet and neither are the process verification methodologies (Ghidini, 2013). This is a huge gap

in the additive manufacturing process because the safety standards cannot be reached for lack of

consistency between the different qualifications.

In addition, the compatibility with other manufacturing processes needs to be validated especially in

regards of space requirements. This includes interface machining, surface finishing, assembling and

joining, and thermal treatments (Ghidini, 2013).

These qualification and standardization challenges are keeping additive manufacturing from being used

on a global scale. Currently, even the liability chain is not clear, and the different types of manufacture

make it almost impossible to have harmonized products. This lack of qualification is shown in Table 23.


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Table 23: ISM Qualification and Standardization Challenges.

Products Qualification and Standardization Challenges

Waste Management

Systems

Standardize elements of waste, such as food/equipment packaging in

terms of material, size and mass, for use in recycling/production devices.

Bio-regenerative

Systems

Hygiene qualifications are a major shortfall as is processing of products

(algae and microorganisms). Standardized production systems

(hydroponic systems, bioreactors).

Closed Loop Systems

Qualify Verification against Feedstock Specifications; Standardization of

feedstock, process, acceptance procedures and life cycle management;

Standardization of key system components with high expected failure

rates.

Medical Supplies

As the increased radiation exposure in space has been recorded to

reduce the shelf life of certain drugs (Du, et al., 2011). Manufacturing in

space might not produce drugs with long enough shelf lives to support a

3 year mission. The effects of radiation on the active ingredient need to

be further examined as well as how the active ingredient is affected

before and after the manufacturing process. Also, qualification of the

drugs produced will be a challenge as it will be difficulty to verify that the

printed dosage is correct, especially for stronger drugs.

Communication

(Antennas and

Reflectors)

Due to the high variability in finished products, the quality of the

reflectors and other antenna parts will impact the antenna gain. This will

reduce the antenna’s ability to efficiently communicate with the ground

segment, thus posing risks to the mission.

Radiation &

Micrometeoroids

Shielding

The suggested shielding is only TRL 6 so there are significant qualification

challenges to meet crew requirements for effective radiation exposure

limits. Microcircuitry and solar cell printing technology is currently only

TRL 5 and would need a further qualification to be suitable for use in a

microgravity environment. The variety and complexity of

microelectronics in spacecraft subsystems may make standardization

extremely difficult, if not impossible, and so printers would need to be

able to custom-print a highly variable set of circuits.

Mental Health Products

Microgravity qualification of terrestrially printed products has yet to

occur. Verification and Competence must be proven before certification

by Astronauts (AMSC, 2018). Qualification of the technology required is

already in the process via ISS testing.


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7 Risks

Installing and operating 3D printers and other in-orbit manufacturing technologies on a spacecraft does

not come without risks. Those risks can be stemming from a multitude of factors such as hardware design

lifecycle, human errors, software issues and thermal stresses to name a few.

Additionally, some risks arise from the lack of having 3D printers and in-orbit manufacturing techniques.

Those risks are described in Table 24 below.

Table 24: Risks, Ratings, and Mitigation strategies.

# Risk Causes Impact Risk

Rating Mitigation

Bio-regenerative Systems/ Bioreactor for Food Production

1 Biological Contamination

- Pathogens - Contamination of spacecraft by biological material

- Equipment failure

- Cleanup requirement

- Contamination of spacecraft by biological material

- Crew illness

1C

- Perform constant maintenance

- Disinfect surfaces - Develop and follow proper hygiene protocols

- Integrate automatic sensors for upkeep

2 System Failure

- Short circuit - High energy radiation

- Human error - Wear and tear

- Contaminant leaks - Environmental contamination

- Fire hazard - Crop damage or loss - Food contamination - Loss or partial loss of oxygen supply

- Loss or partial loss of carbon dioxide removal system

2B

- Perform constant maintenance

- Provide training to repair systems

- 3D print replacement parts

- Store dry emergency food

- Store emergency O2 onboard

3D Printer using Animal Proteins

3

Cell Culture Does Not Survive in Deep Space

- High energy radiation

- Human error - Long-term microgravity

- Loss or partial loss of food source

3B

- Freeze animal cells in shielded containers

- Develop and follow protocols

- Introduce redundant systems (e.g., dry food)


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Rating Mitigation

Heat Melt Compactor

4 Solid Waste Leak


- Human error - Wear and tear - Short circuit

- Spacecraft contamination

- Crew illness 3B

- Add additional insulation layer

- Perform regular maintenance

- 3D print spares

5 System Failure


- Human error - Short circuit - Wear and tear

- Potential solid waste leak

- Accumulation of solid waste

2A


- 3D print spares - Jettison waste into deep space

Refabricator

6 Hazardous Fumes’ Leakage

- Human error - Wear and tear - Short circuit

- Crew illness - Spacecraft contamination

3A


- Use non-hazardous plastics

7 System Failure

- Wear and tear - Human error - Short circuit - Radiation

- Inability to repurpose plastic parts or print new spares and tools

- Potential fumes leakage

4B


- Include redundant systems onboard

8

Improper Production of Plastic Part or Spare

- Human error - Software failure

- Raw material inconsistency

- Risk of other equipment failure

- Wasted system power

3C

- Install non-destructive testing equipment onboard

9 Shortage in Bulk Material

- Improper planning and overuse of bulk materials

- Failure of recycling systems

- Inability to produce in the long run

2C

- Proper planning and assessment in analog missions

- Development of ISRU technologies and recycling


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Rating Mitigation

3D Printing Technologies for Medicine & Medical Products

10 Loss in Active Ingredients’ Effectiveness

- Radiation - Expiry date of active ingredient reached

- Bacteria mutations

- Inability to effectively treat crew

- Risks of depression - Risks of cancer

4D

- Freeze emergency active ingredients in shielded containers

11

Failure of Equipment & Over Reliance on 3D Printers Operability

- Component failures

- Software failures - Human error

- Inability to print required drugs or medical supplies/ products

- Inability to print recreational products, leading to frustration and possibly monotony

3A

- Store a small amount of critical medication on board

- Ensure all parts of the drug 3D printer can be replaced and produced by other part production techniques on board

- Usage of 3D printed components for the printers itself

12 Improper Production of Drug (dosage)

- Incorrect production instructions, component/software failure

- Incorrect drugs administered

- Possible damage to crew health

4C

- Account for control samples of known drugs to validate the process against

- Perform tests to routinely check production dosages are correct

13

Lack of In-space Production Processes Developed

- Lack of research and development of product

- Rushed mission planning

- Inability to produce drugs while in space

- Possibility of running out of needed medication

5C

- Invest in possible drug production technologies and adapt to space production


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Rating Mitigation

3D Printing Technologies for Medicine, Medical Products and Psychological Support

14

Bulk Material Spread in Spacecraft Atmosphere

- Breach in printers chamber

- Printing residues - Post-preparation

- Health hazard (e.g., inhaling particles, eye damage, and skin irritation)

5B

- Protection of bulk materials compartments

- Isolation of printing modules

- Atmosphere evacuation, filtering, and ventilation

15 Communication of CAD Files

- Long delays - Relatively large files

- Inability to produce required specific models

1C

- Good communication contingencies having pre prepared files onboard for most needs

16 Shortage in Bulk Material

- Improper planning and overuse of bulk materials

- Failure of recycling systems

- Inability to produce in the long run

2C

- Proper planning and assessment in analog missions

- Development of ISRU technologies and recycling

17 Insufficient Experience

- Lack of deep expertise in 3D printing of medical drugs

- Mistakes in operations of medical tools and printers

3B

- Train astronauts in 3D printing and medical procedures

- Experiment on analog missions and ISS

18

Damage to Spacecraft Critical Systems

- Recreational game products floating away and getting stuck in spacecraft’s critical systems

- Potential mission failure

3A

- Develop and implement guidelines and protocols


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Rating Mitigation

Manufacturing Technologies for Radiation Shielding & Electronics’ Repair

19

Leak or failure of Cryogenic Liquid Hydrogen system, potentially causing tank explosions

- Insufficient design and safety parameters

- Crew danger - Potential mission failure

- Increased risk of cancer

5B

- Conduct design/safety reviews at all milestones and run lab tests with the intended design

- Perform experimental tests using the liquid hydrogen wall on the ISS

20 Failure of Polyethylene 3D Printer

- Wear and tear - Human error - Short circuit - Radiation

- Inability to print personalized clothing with embedded polyethylene for radiation protection

- Increased risk of cancer

3B



21 Failure of Electronics’ 3D Printer

- Radiation - Wear and tear - Human error - Short circuit - Over-reliance on 3D printing operability

- Inability to 3D print electronic replacements

- Cascade of other system failures

5B



- Develop a safe workbench for manually creating electronics and train astronauts accordingly

22

Failure of Solar Arrays 3D Printer and Assembler

- Radiation - Wear and tear - Human error - Short circuit - Over-reliance on 3D printing operability

- Inability to 3D print solar arrays

- Decreased power generation depending on failure date

4B


- Include emergency nuclear power generator


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Rating Mitigation

Manufacturing Technologies for Communications

23

Failure of 3D Printer and Assembler of Antenna and Reflectors

- Components failure due to wear and tear or radiation

- Software failure

- Inability to manufacture large antenna with a high data rate, leading to restrictions on data transfer rate and potential adverse effects on crew systems and mental health

4B

- Redundant communication systems

- Storage of some critical components with a high likelihood of failing

24

Misalignment of Reflectors or Defective 3D Printed Reflectors

- Control system failure

- Laser scanning system failure

- Decreased antenna efficiency with the potential introduction of noise

3C

- Perform EVA to realign reflectors

- Design reflectors for easy replacement procedures

25

Malfunction of Robotic Arms during Assembly of Antenna

- Hardware failure

- Software failure

- Damage of spacecraft external components

- Potential piercing of hull

5A

- Position robotic arms sufficiently far away from critical external components

- Include “shutdown” code in the software when abnormal behaviors are detected and directly stop robotic arms’ operations

26

Lack of 3D Printer and/ or Assembler On-board

- Cost or schedule issues during the technology development process

- Inability to manufacture higher gain antennas in space, thus limiting the data rate

4A

- Increase investments in in-space manufacturing and assembly of antenna and reflectors


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Figure 33: Risk matrix associated with proposed ISM technologies.


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8 Financial Considerations

This section aims to provide a basis to estimate the future demand for in-space manufacturing capabilities

in deep space crewed missions as well as illustrate cost savings through a case study on spares. As such,

this section will lay out the governmental agencies and private corporations’ plans to perform deep space

crewed missions, thus providing an understanding of the number of deep space trips expected to occur

by 2050 (governmental and private spacecraft).

As of 2019, only NASA and SpaceX have mentioned clear plans to eventually send humans to Mars, albeit

the fact that NASA is first considering using the Moon as a pit-stop (Dunbar, 2018), while SpaceX is

expecting to send the first uncrewed Big Falcon Rocket to Mars by 2022 (Foust, 2018). Other countries

such as Russia have mentioned their willingness to send crewed missions to Mars, first starting with

robotic missions at the next launch window (Torossian, 2018). Additionally, Blue Origin is also a strong

player in the field of crewed space-flights, although focusing at present more on space tourism (Upson,

2019).

Figure 34: NASA’s forecasted available budget and costs of human spaceflight program (National

Research Council, 2014b).

According to the National Academy of Science, NASA’s inflation adjusted budget for human spaceflight is

expected to reach USD ~16 B by 2040 (National Research Council, 2014b), as illustrated in Figure 34. The

ISS could potentially be decommissioned in 2024, thus allowing NASA’s budget to be redirected towards

other projects (Klotz, 2017). It can be assumed that the previously allocated ISS finances, as shown in

figure 34, will be transferred to new projects such as the human deep space exploration missions to Mars


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or asteroids. Regardless of the destination, ISM can help space agencies and private launch providers

reduce launch mass for long duration deep space missions. Hence, eventually reducing cost as the

developmental and production costs for in-space manufacturing systems will be spread over a long period

of time.

8.1 Case Study - Plastic Spares

For the sake and relevance of this section, the following overall assumptions apply:

- The total time required for the mission will be three years (as agreed upon previously)

- The mission will feature a crew of seven astronauts (as agreed upon previously)

- The deep space mission will be to travel to Mars, orbit for a few months and then come back

- The cost of launching a payload to Mars will be assumed to range from USD 45,000 per kg to USD

63,000 per kg, assuming SpaceX’s Falcon Heavy can carry around three to four tonnes of payload

to Mars at a fixed price of USD 135 Million and SpaceX’s current price for launching cargo to the

ISS respectively (De Selding, 2016; NASA Inspector General, 2018). This range is used as a

sensitivity analysis.

- Without ISM capabilities, the mass of onboard stock of spares needed on a spacecraft to Mars is

assumed to be 60% of the onboard ISS mass of stock of spares plus three times the annual ISS

resupply of stock (Refer to table 26)

- With ISM capabilities, which include recycling, the mass of onboard stock of spares needed on a

spacecraft to Mars is assumed to be equal to three times to mass of expected annual ISS failures

in addition to one tonne of raw materials (Refer to table 27)

- Due to the limited information regarding the split of cargo launched to the ISS (e.g., electronics,

plastic tools, metal parts, ceramic components), it is assumed that 30% of the cargo launched to

the ISS are plastic components.

As described in Figure 35, in 2009 NASA developed the Design Reference Architecture (DRA) 5.0 for a

human landing on Mars. According to Foust (2015), NASA is not considering updating this DRA but with

current commercial and renewed interests in Mars, DRA 6.0 may become a necessity. 3D printing and in-

space manufacturing techniques can help reduce the need to launch cargo to Mars twenty six months

prior to the crew launch as illustrated in DRA 5.0.


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Figure 35: NASA Design Review Architecture 5.0 for Human Landing on Mars (Drake, 2009).

Table 25: Information regarding ISS Spares (Owens and de Weck, 2016).

Inputs Value Comments

Mass of Spares Currently Stored Onboard the ISS

13,170 kg (Owens and de Weck, 2016)

Mass of Spares Launched to the ISS per Year 3,190 kg (Owens and de Weck, 2016)

Mass of Spare Failures on the ISS 450 kg (Owens and de Weck, 2016)

Table 26: Mass and Costs of Plastic Spares Required on a Spacecraft without ISM Capabilities.

Assumption & Calculations Value Comments

Mass of Spares Required on Spacecraft to Mars without ISM Capabilities

17,472 kg Assuming 60% of 13,170 kg plus 3 x 3,190 kg (3 years worth of annual resupplies to ISS) (Owens and de Weck, 2016)

Mass of Plastic Spares Required on Spacecraft to Mars without ISM Capabilities

5,241 kg Assuming 30% of 17,472 kg for plastic parts

Cost of Launching the Mass of Plastic Spares Required on Spacecraft to Mars without ISM Capabilities

USD 236 - 330

Million

Assuming launch costs to Mars varying between USD 45,000 and 63,000 per kg (De Selding, 2016; NASA Inspector General, 2018)


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Table 27: Mass and Costs of Plastic Spares Required on a Spacecraft with ISM Capabilities.

Assumptions & Calculations Value Comments

Mass of Spares Required on Spacecraft to Mars with ISM Capabilities (including emergency raw material)

1,620 kg Assuming three times the mass of spare failures on the ISS plus 20% margin as emergency raw material

Mass of Plastic Spares Required on Spacecraft to Mars with ISM Capabilities (including emergency raw material)

486 kg Assuming 30% of 1,620 kg for plastic parts

Cost of Launching the Mass of Plastic Spares Required on Spacecraft to Mars with ISM Capabilities

USD 22 - 30 Million

Assuming that a trip to Mars will experience similar failure rates as the ISS but over a three years period. Assuming launch costs to Mars varying between USD 45,000 and 63,000 per kg (De Selding, 2016; NASA Inspector General, 2018)

Table 28: Mass and Costs of Plastic ISM Equipment Required on a Spacecraft.

Assumptions & Calculations Value Comments

Mass of Additive Manufacturing Facility on Spacecraft to Mars

100 kg The AMF from Made in Space has a mass of 45 kg. It has been assumed that upgraded equipment will be needed

Cost of Launching Upgraded AMF to Mars USD 4.5 -

6.3 Million

Assuming launch costs to Mars varying between USD 45,000 and 63,000 per kg (De Selding, 2016; NASA Inspector General, 2018)

Mass of Refabricator from TUI 1,000 kg Assumption

Cost of Launching Refabricator to Mars USD 45 -

63 Million (De Selding, 2016; NASA Inspector General, 2018)

Based on table 26, the total cost of launching all the mass required to support a three year mission to

Mars in terms of plastic spare parts and components, without the ISM capabilities onboard, is expected

to range between USD 236 to 330 Million. Comparatively, based on tables 27 and 28, a spacecraft

travelling to Mars with plastics’ ISM capabilities onboard will need to account for the following costs:

- Cost of Launching the Mass of Plastic Spares Required on Spacecraft to Mars, including emergency raw material (USD 22 - 30 Million)

- Cost of Launching the Upgraded AMF (USD 4.5 - 6.3 Million) - Cost of Launching the Refabricator (USD 45 - 63 Million) - Cost of Additional Power Requirements (USD 2 Million, assuming 1,000 W power requirements

provided by GaAs solar cells)


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- Cost of Thermal Requirements (Assumed as a percentage of power requirements costs) - Developmental Costs of AMF and Refabricator (USD 2 Million for Made in Space, (NASA

SBIR/STTR, 2019) 2.5 Million for Tethers Unlimited (Iftikhar, 2019) - Manufacturing Costs of one AMF and one Refabricator (USD 1 Million, assumed as 30% of

developmental costs) As such, a spacecraft with ISM capabilities on a three years journey to Mars will require:

- USD 75 - 110 Million in launch costs and operational costs (Assuming ~5% margin of errors) - USD 4 Million in one-time capital expenditure (Developmental and manufacturing costs)

Since the equipment will be used for at least three years, then it is fair to assume that the capital

expenditure can be spread over three years. As such, the developmental and manufacturing costs account

for ~1.3 Million per year. This cost is rather negligible when compared to the launch and operational costs

mentioned previously. Based on the above calculations, it can be inferred that in-space plastic recycling

and 3D printing on a spacecraft travelling for three years can enable up to USD 200 million in cost savings

over a period of three years. Other ISM capabilities discussed throughout the report such as in-space drug

production, and metal, ceramics, and textile ISM can also enable cost savings through a reduction in the

overall mass that needs to be launched into deep space.


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9 Political Considerations

While the use of public private partnerships shall be considered in the following section from the

perspective of a private entity, they have been rejected due to their lack of reliability. Instead, the role of

the contractor for different space agencies will be focused on and the policies of these agencies will be

studied and classified to allow selection of the best partners with which to develop a crewed deep space

mission. Among these space agencies, the Israeli space agency was considered but has been excluded due

to its tight links to NASA.

9.1 Public Private Partnerships

The public-private partnership (PPP) is a form of financing through which a public authority uses private

providers to finance and manage public equipment. In return, the private partner receives a payment

from the public party (Klijn and Teisman, 2002). In the space sector, PPPs have developed mainly because

of government budgetary constraints, the decrease of government-controlled industries and economies,

and exponential growth in the private sector.

However, PPPs do have three main cons that outweigh the advantages that this solution could bring:

- Limited benefits for cost and management efficiency;

- PPPs are funded by the States which may use them to hide their debts;

- Due to the aforementioned cons, delays are frequently experienced when conducting a project

under a PPP (Lampropoulos, 2018).

As the drawbacks of PPPs are significant in nature, one solution remains to allow engagement in this

market: getting a contractor status with a space agency. In order to establish likely partners, a grading of

the main global space agencies has been developed in the section below based on their policies regarding

deep crewed space exploration.

9.2 Agencies Grading

9.2.1 Big Partners

National Aeronautics and Space Administration - NASA

The President of the United States of America has recently taken a number of steps to update old policies

and maintain the U.S.’s competitive advantage as a leader in the industry. A significant proportion of their

budget is spent on the development of new technologies to enable deep space human spaceflight. The

allocated budget is due to fluctuate somewhat in the coming years but overall, will still remain one of the

largest proportions of NASA’s budget (NASA, 2019d).

The signing of space policy directive - 1 instructed NASA to focus on returning astronauts to the Moon and

send humans to Mars. This memorandum specifically focused the directive to these specific goals but

most importantly, included the wording “commercial and international partners” (The White House,

2017). This highlights the U.S.’s awareness of the difficulties in human spaceflight and how those

difficulties are more easily overcome with assistance from commercial and international partners.


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Partnering with commercial companies is evident today with the emergence of commercial crew vehicles.

SpaceX and Boeing are scheduled to test their crew vehicles this year. NASA partnering with these

companies allows for new innovative solutions to arise and also importantly, provide cost-effective

solutions to send a crew into orbit. NASA is not only focusing on industry partnerships for launch vehicles

but also for in-flight technologies. NASA has teamed up with final frontier design to develop a new

intravehicular activity (IVA) space suit which is lightweight, inexpensive, and reliable (NASA, 2018b). NASA

policy to work with these companies is clearly benefiting them in order to quickly develop their human

space flight ability.

NASA’s history of international cooperation has served them well for human spaceflight and it is

understandable as to why they continue with this policy. Today, NASA is actively partnered with ESA,

Roscosmos, JAXA, and the CSA on the ISS. Covering the cost of the development and maintenance of the

ISS was something that could not be done by one agency alone but was possible with collaboration.

Moving forward with its human space flight capability, NASA has partnered with the ESA to develop the

Orion Multi-Purpose Crew Vehicle (Orion MPCV) with ESA leading on the development of the service

module (ESA, 2015). Again, this project enables NASA to spread the costs while improving the

development of deep space Orion MPCV.

NASA currently has three major milestones on their way to deep space human space flight. The first being

the development of the Orion Multi-Purpose Crew Vehicle (Orion MPCV). Orion has the capacity to carry

up to three crew members for over 21 days. NASA will also have to complete the Space Launch System

(SLS). This is a large launch vehicle capable of sending Orion into deep space (NASA, 2019e). Finally, NASA

aims to develop the Gateway. The Gateway’s goal is a sustained presence around and on the Moon and

to develop and deploy critical infrastructure required for operations on the lunar surface and at other

deep space destinations” (NASA Advisory Council, 2018). It will act as a proving ground for later Mars

missions and will enable a human presence in cislunar space, cementing NASA’s human presence in deep

space.

European Space Agency - ESA

ESA has had a strong presence in human space flight and aims to position itself at the edge of human

spaceflight capabilities (ESA, 2019). ESA’s rationale behind its focus on human spaceflight and exploration

is due to the fact that it aids the socio political goals in the vision of European identity and human

spaceflight and exploration are important symbols of space to the public (ESA, 2007).

ESA wants to be an active agent when it comes to missions beyond LEO (BLEO). It has the goal of being a

key partner of NASA for BLEO missions. Apart from having previous positive partnerships with NASA, ESA

has partnered with NASA for the development of the service module of the Orion MPCV capsule. This was

a great decision from a human space exploration policy perspective as it provides ESA with the capability

to send crew on the Orion capsule to BLEO. ESA currently has no crew launch capability and no plans for

the development of one. ESA also has plans to get involved in NASA’s deep space gateway (DSG) mission.

It has a number of technologies such as the European System Providing Refueling, Infrastructure and

Telecommunications (ESPRIT) (ESA, 2017).


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ESA also is exploring the possibility of partnering with the Chinese National Space Agency (CNSA) on the

Chinese crewed space station. ESA would expand its possibilities to conduct scientific research in orbit as

well as expanding the market for European spaceflight products (ESA, 2017).

The development of in space manufacturing to enable crewed deep space exploration, would help ESA on

their path towards human BLEO missions. An additional and real benefit ESA could see from the

development of these technologies in Europe is the spin-offs and economic advantages that come with

them. As previously mentioned, ESA aims to promote growth within Europe through the space sector and

this would be another avenue to achieve this.

China National Space Administration - CNSA

China’s space policy is led by China’s five-year national plan. In this plan, China has a main focus on

manned spaceships, space stations, lunar and Mars exploration (CCPA, 2016).

China Manned Space Program

China's manned space mission is mainly dominated by the China Manned Space Program (CMSE). CMSE

has a "Three-step Strategy" of development：

- To launch a crewed spaceship, build up primarily integrated experimental manned spacecraft

engineering, and carry out space application experiments

- To make technology breakthroughs in Extravehicular Activities (EVA) as well as space rendezvous

and docking of manned spaceships and spacecraft, launch a space lab, and provide a solution for

space application of a certain scale with crew on a short-term basis

- To establish a space station and provide a solution for space application of larger scale with crew

on a long-term basis (CMSE, 2019)

CMSE three current missions of which two are of particular interest in regards of deep space crewed

mission:

1. Tiangong II

Tiangong II is a space laboratory, also can be described as crewed spaceflight vehicle designed for carrying

out space experimental activities. It is the prototype of the space station which means it's smaller than

the space station in scale. The major tasks include making breakthroughs on spaceflight vehicles’ space

rendezvous and docking and assembly control technologies; breakthroughs on key technologies relating

to crew’ mid-term space mission, long-term auto flight of space vehicles, key technologies such as

regenerative life support systems and cargo spaceship replenishment and preliminary investigation of key

technologies relating to space station construction (CMSE, 2019).

2. Unnamed crewed Space Station

This Space Station System is comprised of the Core Capsule, Experiment Capsule I and Experiment Capsule

II, with the aim of building a reliable operating space station, and providing long-term support for the

onboard healthy living for the crew (CMSE, 2019).

Roscosmos

The Russian space program has suffered from poor exchange rates which can be seen in its most recent

10-year program. The 2016 – 2025 budget ($20.5 billion) is less than half of the last decades budget ($56.4


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billion). With this said, Russia is still aiming to keep a human presence in LEO with additional modules

planned for the ISS which can become independent stations.

The Kremlin still promises to complete the assembly of the Russian segment of the International Space

Station, which has remained unfinished for nearly two decades. According to this plan, a total of three

new modules were planned to join the ISS: the Multi-purpose Laboratory Module (MLM); the Node

Module (UM); and a new-generation laboratory and power supply facility dubbed NEM-1. These

components were supposed to be sent in 2017, the latest Russian plan for the assembly of the ISS, set the

delivery of the UM to the Russian Segment of the outpost for November 2019 (Zak, 2016).

Roscosmos had ambitious plans to build a giant super-heavy rocket, which would enable Russia to land its

cosmonauts on the Moon by the end of the 2020s and begin setting up a permanent base there. But both

the government officials and Roscosmos stressed that the first priority for the program will be

communication and broadcasting satellites for now. Also, according to the approved strategy, Roscosmos

still remains committed to shifting human space launches from Baikonur in Kazakhstan, to the new

spaceport in Vostochny in the Russian Far East. This would need a new launch pad and rocket. The new

facility is promised to be ready in 2021, and thus a new generation of spacecraft is needed (Zak, 2016).

Roscosmos promised to launch the uncrewed prototype of the Soyuz replacement in 2021 and to send

the first crew to the ISS aboard the new ship in 2023. The Moon landing still remains the strategic goal of

the Russian human space flight program (Zak, 2016).

9.2.2 Future Players

JAXA

JAXA has three policy objectives: ensure space security, promote the use of civil space, maintain and

strengthen the science and technology industrial base (National Space Policy Secretariat, 2017).

Although JAXA has no crewed launch capabilities and no plans to develop any, it currently has 10

astronauts and a strong presence when it comes to human space flight. Like ESA, JAXA is one of the five

members of the ISS with their own ‘Kibo’ module for scientific research. However, JAXA’s aims for human

spaceflight are currently to conduct research in a microgravity environment. They have recently met with

NASA to share their views on space exploration beyond LEO but have yet to make any solid agreements

to enable them to travel beyond LEO (JAXA, 2018).

ISRO

On November 7, 2006, the Indian Space Agency (ISRO) approved India’s first manned space mission. On

July 2018, ISRO successfully conducted the first flight test of the "Rocket Escape System" at the Satish

Dhawan Space Centre (ISRO, 2018). At the end of 2018, ISRO announced three Indian astronauts will be

sent to space by 2021, as part of India's ambitious Gaganyaan project. The Indian government also

allocating 100 billion rupees ($1.43bn) for this mission (Phys.org, 2019).


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Iranian Space Agency

Iran’s aim is to send an Iranian crew to space within eight years. This goal was put forward by the Iranian

Aerospace Research Institute (member of the Iranian Space Research Center), more specifically the aim is

to send astronauts to sub-orbital space in collaboration with a private Russian company (The Straits Times,

2017).

While Iran is not ready yet to send humans to space, its space program is promising and its recent launch

achievements put the country as a potential future space faring nation. Iran’s ambitions are clear and it

would be unreasonable to ignore them.

9.2.3 Recommendations

Table 29: Recommendations for working with agencies.

Policy includes crewed

missions

Policy includes Deep Space crewed

missions

Capacity to send humans into deep space

within 30 years

Political and Economic stability

Recommend partnership

1 - Yes 2 - Potentially

3 - No

NASA Yes Yes Yes Yes 1

ESA Yes Yes Yes Yes 1

CNSA Yes Yes Yes Yes 1

ROSCOSMOS Yes Yes Yes No (Economical) 2

JAXA Yes No No Yes 2

ISRO Yes No No Yes 2

Iranian Space Agency

Yes No No No (Political) 3

Table 29 summarizes the agencies’ policies from the previous sections, outlines how the policies are in

line with deep space human spaceflight, and quantifies their suitability for a partnership focused on deep

space exploration.

Some key features to note are that Roscosmos is currently economically unstable, as mentioned in Section

9.2.1 of Chapter 2. The Iranian Space Agency can be considered to be politically unstable due to the

current threat of conflict and concerns around nuclear arms (The Washington Times, 2019).

NASA, ESA, and CNSA are all recommended for partnering with for the purpose of deep space exploration

due to their capabilities (both now and in the future), their policy, and their stability. It is highly likely that

all three will have deep space human mission capability within the next thirty years. Roscosmos, JAXA,


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and ISRO are all listed as potential partnerships as they all have crewed missions included in their missions

statements but either lack current plans and/or capability to carry out deep space human missions or are

subject to economic instability. The Iranian Space Agency has crewed missions plans however is not

recommended to partner with due to a lack of future plans and regional instability.


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10 Legal Implications

10.1 Legal framework

This section would not be relevant without a defined framework, hence for the sake of consistency, the

following bases shall be laid:

- The point of view is from a private entity;

- Based in Luxembourg;

- Working as a contractor for governmental space agencies.

In regards to the mission, space law is not relevant since the commercialization of space will not be

addressed and nor will weapons will be manufactured. Therefore, the mission in question falls within the

framework of European laws as the company is headquartered in Luxembourg.

10.2 General considerations

The general considerations usually include the facility registration, the bandwidth and the orbit allocation.

However, with regards to the framework foundation expressed at the beginning of this chapter, the

private entity shall work for space agencies as a contractor meaning that those considerations shall

require assessment only by the latter since only the 3D printer(s), and no spacecraft of any kind, would

be provided.

10.3 Intellectual and Industrial property issues

10.3.1 Intellectual property

Intellectual property law is a branch of general law that includes all the rules applicable to intellectual or

intangible creations. Those are part of what can be assessed as: "intangible property". Moving forward,

3D printing techniques means it is now possible to duplicate any object. Users could then, theoretically,

copy anything without the authorization of the intellectual property rights’ owner of this object.

Nevertheless, it is not in the scope of the mission to reproduce any object that would fall under intellectual

property protections. Indeed, the tools, the parts or even the medicine manufactured are protected by

the industrial property law.

10.3.2 Industrial property law

Industrial property allows the protection of technical creations; mainly patents, ornamental creations

(drawings & models) and distinctive brand signs.

Regarding that particular legal framework, it is in the scope of the mission to print tools or part of the

spacecraft that could be missing or could break. In this case, the patent of said part would be required. In

fact, a patent is a protection granted by the government to reward an inventor and the fruits of their

ingenuity. A patent makes it possible to obtain a monopoly, or in other words absolute control, on an


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invention. That said, to avoid any legal issue, it will be fundamental to be sure to obtain the patent before

repairing or creating any parts, tools or medicine otherwise the work done will be considered as

counterfeiting.

Nevertheless, it must be noted that copyright and licensing work both ways. Indeed, if the private entity

aims to create and produce original models for 3D printing, the question of whether or not they want the

models to be available to others or not should be raised. And if not, a patent will be needed in order to

secure the copyright (Kuliś, 2017).

10.3 Goods or services provider?

In order to qualify the mission and thus the applicable law, a distinction between being a provider of goods

or services must be made.

10.3.1 The difference between the two notions

On the one hand, goods are tangible. They consist of products that can be acquired for use or

consumption. Depending on the nature of the good or product, it can be consumed from the first use (e.g.

a chocolate bar or a soft drink) or can be used more than once, when the product does not lose its original

characteristics (e.g. a pen or shoes).

On the other hand, services are intangible. They are actions which may require special skills or resources

provided by a third party. When paying for a service, we do not become the owner of the service, only

the result of the action provided by the service provider (e.g. a haircut) or the right to service (e.g. legal

advice from a lawyer, a room in a hotel).

10.3.2 Manufacturing in orbit only implies providing goods

Providing one or multiple 3D printers for a crewed deep space mission only implies to provide goods for

said mission. In fact, the crew would only use the printer to create either tools, food or even medicine

which does not imply any particular transfer of know-how or capacity coming from the private company.

However, the latter binds itself to provide the goods wanted which brings the liability question: to what

extent the company could be responsible in case of a failure?

10.4 3D printing and liability: Tort law

10.4.1 Tort law

Tort law or civil liability law is a branch of law that governs the conditions under which a victim can obtain

compensation for his/her prejudice. In other words, for each harm there is a reparation of some kind.

In tort law, there is a branch that is of particular importance for the mission statement: the liability for

defective products’ law. This is recognized by the European Directive on liability for defective products

(85/374/EEC), under which any producer of a defective movable must make good, the damage caused


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(Directive 85/374/EEC). As stated within the submitted framework, the proposed company is

headquartered in Luxembourg, thus it is submitted to European law and this Directive applies.

The responsibility of the manufacturer rests also on the seller of a good’s responsibility. Under this legal

framework, the manufacturer is liable for any defective material or, more generally, for a defect which

makes the goods unsuitable for the intended use. Obviously, the defect must exist at the time of the sale,

be unknown to the purchaser on that date and present an issue of note. Ignorance of the defect by the

manufacturer does not affect the liability of the latter under the quality guarantee.

Regarding the responsibility of the manufacturer, there is a common chain value of responsibility that

exists in European law which is stated as follow:

Supplier → Manufacturer → Seller → Buyer

Nevertheless, this chain-of-sales concept is not relevant in the 3D printing industry because there is a large

number of suppliers that could possibly be held accountable. Here is a non-exhaustive list of potentially

liable actors:

- The manufacturer or the supplier of the 3D printer and/or its printing materials;

- The printer’s owner;

- The person who sold or designed the original object;

- The person who created or shared the CAD file;

- The person who created the object using the printer;

- The person who sold the 3D-printed object…

To date, there is still no specific jurisprudence relating to the rules of civil liability for a product produced

in 3D. It is an unknown territory for manufacturers. Indeed, as the defect can come from a lot of possible

scenarios, it is almost impossible, using the traditional tort law, to sort out who is actually responsible in

case of a defect. Those possible scenarios can include:

- The original product design used to create the 3D printed object was defective;

- The original CAD file was defective;

- A defect was introduced into the CAD file as it was uploaded to a file-sharer;

- The CAD file was corrupted during the process of downloading;

- The defect was caused by an issue with the 3D printer;

- The defect was caused by an issue in the raw material used in the 3D printer

- Human error in implementing the digital design caused the defect;

- Human error in using the 3D printer and/or the raw material.

However, while there is an almost infinite number of actors that could be liable, there is a way to avoid

legal difficulties in this area: having a perfect process of manufacturing (Freeman, 2013). Processes allow

the manufacturer and the client, here the space agencies, to be on the same page regarding the

expectations and the quality of the product. With a battery of test and requirements, the responsibility of

the private entity can be reduced.


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10.4.2 For the crewed mission: Health issues and Tort Law

In the case of the proposed mission, the crew present will have to live in a closed environment, far from

Earth which could be dangerous for the worker’s physical health.

In fact, a study conducted by researchers from the Georgia Institute of Technology and from the UL

Chemical Safety in April 2018, showed that 3D printers may be dangerous to human lungs due to the

presence of nanoparticles. It was concluded after two years of research that “many 3D printers emit

ultrafine particles during operation”. These particles, which are measured in nanometers, are breathable

and once they reach the lungs, they persist throughout life (Underwriters Laboratories, 2018). All research

conducted on 3D printers thus far, appears to reach similar conclusions: 3D printers are harmful to human

health regardless of the model chosen. Only one solution has been advocated thus far: staying away from

the printer when it is working. This recommendation that is not an option in our case thus risk mitigation

plans are required, for example options could include using the printers in an enclosed area with strong

air filtering and personal protective equipment.

Thus, regarding this study it might be a challenge to have multiple printers onboard for a three years

mission. This significant risk in regards to crew health would require addressing at an insurance level in

tandem with any mitigation plan.


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11 Ethics

The in space manufacturing process must be risks assessed and evaluated, as with any on-Earth activity.

These newly developed techniques are created by humans to impact on human lives. The welfare of said

humans is paramount to mission objectives being successfully completed in any crewed mission. The

following section shall attempt to highlight some of the social impacts and ramifications of the actions

under discussion.

Since Antiquity, ethics has been a subject of reflection to which many philosophers and thinkers have

contributed, from Aristotle and Descartes to Spinoza and Kant to name a few. Through this profusion of

philosophical works and research in the human and social sciences, it appears that there is no consensus

definition of ethics. The Greek etymology (ethos and ethicos) and Latin (mos and moralis) propose two

meanings of the term "ethics":

- A set of rules enforced and respected by the members of a society, rules given as a guide to

conduct and stated in terms of good and bad

- A philosophical discipline that reflects on these rules and representing their foundations and ends

(Cruz, 2017)

For the majority of authors, ethics is considered at the very least as defining what is good and what is

wrong. The origin of these values is very varied. The individuals draw them from religion, the belief in a

superior technology, the fear of scientific progress, the rational reflection, the search for creation of

economic value, social survival or even education. In addition, in a given organization, each individual has

an ethic that serves as a benchmark when he/she must make a decision and act. Ethics can, therefore, be

defined as a way of thinking that guides individual actions (Cruz, 2017).

11.1 Ethics and Automation

Ethical considerations in regards to in space manufacturing are not limited to situations where humans

are continuously present. Robotics and automation ethics is a sub area of ethics dedicated to examining

the ramifications of the described scenario (Tzafestas, 2018).

There are a number of questions that any developer should be mindful of during the decision making

phase of facility development. These can be most easily understood within two categories, the impact of

automation on society, and the relationship between humans and artificial intelligence (AI).

The impact of automation is already visible in society, for example, the impact of self-service checkouts

on job opportunities in supermarkets. A fully automated in space manufacturing facility would require

high levels of sophistication in its robotics. How will on Earth manufacturing jobs be impacted? Would

meeting this mission objective make humans obsolete? Ethicists have identified this as a question that

will require an answer within the foreseeable future (Rotman, 2013). Further to this, AI technological

advancements are beginning to lead to socially competent robots (Tzafestas, 2018). Would a socially

competent robot have the same social needs as humans and if so, what supports would robots require in


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regards to their well-being if placed within a fully automated facility? While there is currently no solution

to these potential issues, mindfulness of their existence would be useful in development planning.

11.2 Mimicking Mother Nature

The main consideration of any ethical assessment is how any new technology can be misused. Bio-printing

could lead to changes in the human body that should not be possible without technical assistance. This

could lead to the creation of super-humans. With bio-printing, it would appear that Medicine shall

eventually be able to create organs with higher capacities and a longer life expectancy than is naturally

possible (Gilbert, et al., 2017).

This would be an artificial enhancement of the human body that could possibly lead to the creation of

synthetic humans. While bio-printing is a significant advancement in medicine, the limit between

augmented humans and the simple cure is very thin. For this reason, bio-printing must remain regulated

and must be used for the sole purpose of saving lives (Gilbert, et al., 2017).

With that in mind, the following questions arise: by creating bio-printing, are humans trying to play “God”

creating the human equivalent of hybrid-creation attempts between animals? And shouldn’t Nature be

left to its preset limitations?

Added Value

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ADDED VALUE

In this paper, the benefits of using in space manufacturing have been highlighted and discussed. In

addition to this, here is one fundamental added value: the positive environmental impact of using this

technology. This impact can be further increased by the democratization of in space manufacturing.

When launching a Soyuz rocket, the booster launchers release kerosene and liquid oxygen. Ariane 5, and

Vega, to a lesser extent, both exhaust hydrochloric acid and alumina. In addition, a large amount of water

is projected onto the launching table which results in the increase of the cloud of combustion, and, finally,

a large part of the pollutants emitted fall close to the launch area (David, 2017).

These gases remain on the ground distributed radially approximately 1 km around the launching pad.

Further information is required on the environmental impact of rocket launches and re-entering space

debris on the middle and upper atmosphere. Research supports the conclusion that rocket emissions and

debris are directly affecting the ozone (David, 2017).

This issue can be mitigated by in space manufacturing. Utilizing these technologies can decrease a

significant percentage of the supplies required for a crewed deep-space mission via re-supply launches.

Consequently, the associated greenhouse gases would be decreased (Ghidini, 2016).

In addition, the reduced requirement of re-supply missions will subsequently reduce energy consumption

and the CO₂ footprint on Earth. Furthermore, as every product can be used multiple times, the recycling

process is not needed and therefore energy would be saved, in particular for metal components (Ghidini,

2016).

The majority of manufacturing methods, inclusive of 3D printing, have numerous negative side effects on

the environment. By utilizing in space manufacturing, these environmental impacts can be mitigated

through reduced power consumption, elimination of nanoparticles, greenhouse gas exhaust, and

reduction of chemical run-off. Hence, in space manufacturing can be deemed to be the lesser of two evils

(Keppner, et al., 2018). Although the number of rocket launches to re-supply is not significant, the benefits

of using space as a medium for creating products are not negligible. Furthermore, there will be less

wastage since any product printed in space will be put to use whereas stockpiles may or may not be

utilized.

Therefore, despite the fact that there is currently no precise data about how much gas is released,

reducing the number of rockets launched and the quantity of material needed to resupply the missing or

broken ones reduces the supply chain.

Added Value

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Finally, according to Ghidini (2013), 3D printing can protect the environment by guaranteeing:

1. Significant weight reductions: can go up to 95% but is usually is a bit more than 50% of the initial

weight that is reduced;

2. Radical reduction of waste material compared to classical subtractive manufacturing;

3. Additive manufacturing lead time which could be shorter by months compared to traditional

manufacturing;

4. Drastic reduction of manufacturing steps required;

5. Decrease in energy consumption and reduction of CO₂ footprint;

6. Process speed optimization.

In-space manufacturing is thus beneficial to the environment (David, 2017).

Recommendations

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RECOMMENDATIONS

Across this report, several manufacturing techniques have been proposed to address the constraints and

requirements that emerge from sending a crew into deep space for a period of up to three years. The ISS

was utilized to set a baseline to establish the essential needs of a crew and common bottlenecks

associated with planning a 3-year mission. The following section aggregates the key recommendations

tailored to (i) space agencies and private space players with plans to send a crewed mission on a 3-year

journey as well as (ii) the space and 3D printing industries as a whole.

Food and Health Manufacturing Processes

Life support and bioregenerative systems are suggested to operate in parallel to support basic life needs

in an efficient manner. Algae processing, bioreactors to grow microbes, and plant generation have been

identified as key developments in bioregenerative systems because of their ability to nourish crew

members and produce adequate atmospheric requirements. Some experiments have been conducted on

the ISS, but there is still a significant technological gap to apply these solutions to more advanced mission

architectures. Section 2.1 of Chapter 2 goes into more detail on how life support, bioregeneration, and

waste management can operate in parallel effectively.

Medical Supplies and Drugs

Medical standardization is required in order to streamline the ISM process for medical devices and

medicine. Medical devices are currently 3D printed on the ISS with FDM techniques while manufacturing

medicine still remains a terrestrial challenge. To create standardization and personalization, it is

recommended to create patient-specific database formats for astronauts using additive manufacturing

profiles. To validate manufactured medicine in space, it is suggested to further develop the following

technologies on the ISS: Inkjet 3DP, Thermal Inkjet (TIJ) Printing, and Fused Deposition Modeling (FDM)

with respect to the printing of medicine in space.

The final area for improvement is shelf life of medicine. Advanced radiation shielding techniques will

heavily support this process and have been detailed in Section 2.6.2 of Chapter 2. This continues to pose

a risk to long duration missions.

Mental Health

It is recommended that space agencies place an emphasis on crew’s hobbies and family dynamics.

Specialized games and scale model figurines of family members can be 3D printed using FDM techniques

to help astronauts feel more connected to home. Section 2.5 of Chapter 2 provides further detail

regarding this recommendation.

Standardization and Commercialization

Standardization and commercialization have been identified as key areas to further develop with respect

to ISM. Since this is still a niche industry, proper standards and design guidelines such as handling,

Recommendations

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operability, and reliability will need to be continuously monitored on the ISS while the ground support

revises and documents and issues. Commercialization is evolving rapidly, with Made in Space and TUI

leading the way, but this market would benefit from more actors. To this point, agencies and commercial

companies should consider creating a standard database consisting of 3D models for parts exhibiting high

failure rates. This would provide astronauts with the ability to quickly react to situations as they arise.

With deep space communication latency, astronauts may not have time to wait for ground support to

provide solutions.

It is also suggested for space agencies and private companies to create modular designs with as many

common or identical parts as possible. This way, ISM can easily be utilized for replacement parts and

assembly will be simpler.

In conjunction with additive manufacturing, robotics should be developed to remove as much human

interfacing as possible for secondary processing of 3D printed parts. As there will always be some human

interfacing required, astronaut training will need to be developed and tailored to specific and detailed

operations. Astronauts must be able to identify the failed components within the 3D printers and repair

them readily. This might require launching stock emergency spares with known high failure rates.

The final recommendation for this section is to update the Design Review Architecture for Human Landing

on Mars from 5.0 to 6.0. Since a Mars mission closely follows this reports mission architecture, it may be

beneficial for NASA to consider updating their design guideline to include ISM techniques with a focus on

additive manufacturing; enabling cost reductions on the long term.

Electronics

The industry should focus on developing space-grade recyclable electronic and electrical components that

can introduce higher sustainability on deep space missions. As highlighted in Section 1.1 of Chapter 1, the

most common failure today on the ISS comes from electrical components, hence a clear emphasis should

be placed on the ability to mitigate these risks without the need of resupply or specialized spare parts.

Validation for 3D printed electronics should occur in parallel with the creation of the FabLab ISS additive

manufacturing plans. Aerosol jet printing has been the primary method identified in this report for further

development with a TRL of 5.

Metal Printing

The FabLab project associated with the ISS is currently planned to complete by 2024. It is recommended

that this validation process continues to move forward efficiently with key actors such as Made in Space

and TUI. The most interesting improvement currently being developed terrestrially is the MAMBA for its

ability to integrate recycling as well as 3D printing. This integration between recycling and manufacturing

will be imperative for deep space crewed missions.

Recommendations

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Assembly

Assembly in space is critical in reacting to the extreme environments posed by deep space missions. It is

recommended to study 3D printing of radiation protection materials such as aluminum and polyethylene

and document the repair and assembly process.

In addition, it is advocated to further develop the capability to 3D print large antennas. This will be used

to mitigate the effects of long distance power loss during communication. The large structure printing and

assembly of antennas are not yet validated but require further study and present an interesting value add.

Further information can be found in Section 3.2 of Chapter 2.

Sustainability

The sustainability that ISM can generate for a spacecraft is likely its largest benefit. As such, it is suggested

to develop more compact printers capable of printing multiple materials. This will help reduce the

required volume capacity and overall mass for the various ISM techniques.

Further advancement of recycling techniques within the realm to ISM will greatly benefit future deep

space crewed missions. This eliminates the need for resupply if performed correctly and efficiently. TUI is

heavily focused in this area with their Refabricator and MAMBA products. Although they have not been

tested in a space environment, successful integration will provide an enormous improvement in the way

repairs and spares are approached.

Another recommendation is to increase the sustainability of the ISS itself to begin to simulate and

replicate deep space mission parameters. Attempting to reduce the number of resupplies to the ISS by

leveraging ISM will help define further technology gaps and areas of improvement. The recommendation

is to start by reducing the resupply frequency to once per year. As the ISS operates in LEO, this will be a

low risk feasibility study since the required material can be supplied in the case of emergency.

With a larger emphasis being placed on ISM, it is recommended to focus on efficiency and power

consumption requirements. Having more 3D printers on board will drive higher power requirements and

more complex power generation architectures. At the same time, having the capability to manufacture

and assemble solar panels directly in space can enable higher power generation as mentioned in Section

3.2.2 of Chapter 2. This will need to be a central focus in planning for future deep space crewed missions.

References

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CONCLUSION

3D printing emerged late last century. It started as a design aid and prototyping tool but its potential

seized the imagination and business instincts of many. The ability to rapidly produce fully customizable

objects opened up a realm of possibilities. This potential was quickly transformed into applications and

hardware models. While a community of “do it yourself” makers was growing, the technology started to

seep into the traditional manufacturing industry, mainly in the modeling and prototyping phases. As the

variety of 3D printable materials and quality evolved, manufacturers started producing end products

through additive manufacturing.

Today, 3D printing technology touches upon almost every industry but only for a specific set of products.

The most developed 3D printing technologies operate using plastics, but new 3D printing technologies are

focusing on other materials such as metal, glass, concrete, food, and textiles to name a few. 3D printing

applications in the industry will generally either be high end, benefitting from the ability to customize the

products, or experimental. On the other hand, the technology is usually not used in high volume

production lines and the price for a market ready product will be high.

Despite those challenges, the space industry is relatively resilient to these disadvantages. In fact, space

missions usually do not require mass produced components, subsystems and systems. Additionally, NASA

in collaboration with commercial partners such as Made in Space, has developed and operated ISM

technologies with a price tag which is negligible compared to the mission budget and the overall return

on investment in the form of cost savings in the long term.

A space mission experiences a plethora of premature failures combined with expected wear and tear. The

ability to readily produce on-demand components in space can enable space stations’ personnel, with

minimal expertise in manufacturing, to tend to the needs of the space stations’ systems. As such, in-space

manufacturing technologies are highly compatible with a crewed mission operational environment,

reducing the amount of spare storage required.

While LEO missions such as the ISS can act as experimental platforms for ISM technologies, the real

challenge for these technologies will be in such missions where resupply is unavailable e.g. deep space

exploration missions. As such, this report was developed around the idea of leveraging operational and in

development ISM technologies that can support a 3-year deep space crewed mission of seven people.

References

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This report’s conclusions are laid out below:

1. Like in many space related industries, the ISM industry is still in its infancy, with governmental

agencies, such as NASA, partnering with commercial entities to advance the industry and

potentially enable the creation of a space economy.

2. The technologies identified from this topic are split in:

a. 3D printing by crew within a space habitat.

b. 3D printing of large structures and robotically assembling them out in space.

c. Manufacturing technologies which are not 3D printing (e.g., recycling, assembly,

biological and chemical processes).

3. Developmental and manufacturing costs of ISM technologies will be amortized over a long term,

thus providing an incentive to shift the focus from an open loop resupply paradigm to a closed

loop one. The ISS is expected to be used as a platform to elevate the TRL of ISM technologies in

order to later on be ready for long duration deep space expeditions.

4. ISM enables products to be developed that are not easily launched into space. For example, large

structures face many launch constraints and have good chances of being developed commercially

through ISM. Although TRL is relatively high, operational status is not clear.

5. ISM technologies, other than 3D printing, exhibit differences in TRL, some of which are highly

developed while others are still at a relatively conceptual level.

6. When the ISS experimental platform will end its operational lifetime and funds will be redirected

towards long distance exploration mission; thus the TRL of 3D printing is required to be at 9 in

order to accommodate the mission needs.

7. While plastics 3D printing is fairly developed, a gap exists in metal and electronic 3D printing to

respond to failures similar to those encountered on the ISS today.

8. Additional crew needs in future deep exploration were identified, mainly in medicine,

communication, and radiation shielding. It was also found that current 3D printing technologies

have limited ability to face these challenges.

9. The recyclability was pointed out as a major contributor to long duration deep space missions

sustainability, and any manufacturing attempt should address the recyclability of the final product

at its end of life.

10. The modularity of components was found to be an assisting design tool to make the best use out

of 3D design parts allowing to print minimal required parts to address the failure.

Having an “ideal” 3D printing manufacturing machine capable of anything from any material would

obviously be an asset for space exploration, but it is also a science fiction tool. Currently, printing anything

and everything is not possible. In addition, mass and power budgets are not sufficient enough to develop

better printers. Still the potential of such a device is extremely attractive on Earth and in space.

Advancement in 3D printing technologies in space will occur hand in hand with the launching of more

crewed missions to explore our surrounding planets and moons. This technology has great prospects, in

essence the further distance humankind travels, the more it will advance.

References

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