Deep Space Navigation - NASA

Deep Space Navigation, the Celestial Reference

Frame, and Very Long Baseline Interferometry3rd U.S. VLBA Reference Frame and Navigation Meeting

Joseph Lazio, Joseph Guinn

Earth at LaunchEarth at Arrival

Mars at Launch

Mars at Arrival10 months

15 min light time

Typical Earth to Mars

Trajectory

Deep Space Navigation 2

Mars, Moon, and Small Bodies

GRAIL: Dual Spacecraft Formation

(2011-2012)

Dawn:

Low Thrust

Asteroid

Orbiter

Stardust: Comet Coma Sample Return

Deep Impact: Comet

Tempel 1 Impactor

(2005)

Re-Purposed as

EPOXI: Hartley 2

Flyby (2010)Earth Return

(2006)

Mars

Reconnaissance

Orbiter (MRO)ESA Mars

Express

Mars Odyssey

Operational 2001-2014

MAVEN

2016 2018 2020

Curiosity

Mars Science

Laboratory

Mars 2020

Science

Rover

2022

ESA

ExoMars

Trace Gas

Orbiter

Mars

Exploration

Rovers InSight

ISRO

MOM

Phoenix

UH

F A

ntenna

Cam

era X

-Band P

atch Arra

y

IRIS

Radio

C&

DH

Electronics

EP

S E

lectronics

Star T

racker &

AC

S E

lectronics

MM

A H

aWK

Solar P

anels

Additional

Solar P

anel

AC

S C

old Gas

(hidden)

Batteries A

CS

RW

A (3x)

(hidden)

New Horizons Pluto

Juno

Jupiter

Orbiter

Cassini Saturn Tour

Outer Planet MissionsInterplanetary

CubeSats

Europa Clipper

Galileo

Jovian

Tour


Deep Space Navigation

1. Positions and Physical Models of Celestial Bodies

2. “Flyable” Trajectories

3. Fly the Trajectory

Includes VLBI and Celestial Reference Frame

4. High precision dynamic and measurement models– Relativity – lots of gravity and high speeds tweak onboard clocks

– Non-gravitational – spacecraft attitude control, venting, leaking and

outgassing perturb trajectories

– Maneuvers

Four Things Needed Beyond Low Earth Orbit

1. Celestial Body Positions – Past, Present, Future

Orbits refined using

• Earth RADAR

• Astrometric Images

• Planetary orbiters near

objects of interest

Locations & Uncertainties of Planets, Natural Satellites, and Small Bodies

5Deep Space Navigation

NASA/JPL maintains Horizons Database (Google Maps of the Solar System)

Currently contains ~ 650,000 Objects


Optimal Trajectory Design

2. “Flyable” Travel Plan

Hohman transfer orbitCredit: Phoenix7777

Interplanetary Superhighway


Aside: Low-Thrust and Low-Energy Trajectories


GRAIL low-energy

trajectory enabled mission

to reduce fuel

requirements and lunar

arrival velocity

Earth-Moon

Rotating Frame

Earth

Asteroid Retrieval Mission

Distant Retrograde Orbit (DRO)

Stable storage orbit (> 100 yr)

proposed by NASA/JPL MD/Nav

Dawn low-thrust trajectory

achieved total Dv > 10 km/s.

Allowed both Vesta and

Ceres to be explored



Spacecraft state vector =𝒙, 𝒗; 𝒕

➢ Ensure that actual

trajectory is sufficiently

close to planned

trajectory

➢ Requires measurements

from which state vector

can be estimated

➢ Requires monitoring• Relative motions ~ 10 km/s

• Non-gravitational forces


R

right

ascension a

declination d

• Range (R)In practice, not used often

• Range-rate ሶ𝑹 or Doppler (vz)

• Plane of sky (a, d)➢ Measured relative to Celestial

Reference Frame

• Proper motion (ma, md)In practice, not used


Collect Measurements

DSN Advanced

Interferometric

(DDOR, VLBA)

ESA

DSN

State of the Art

Ground-based

Radio Navigation(MER, PHX, MSL)




∆DOR provides Plane-of-Sky

measurements

• Determine position of

spacecraft relative to

stationary reference source

of known position

• Essential beyond lunar

orbit

• Complementary to line-of-

sight from Doppler and

RangeOptical analogy is “Optical

Astrometry”▪ Uses star catalog

instead of quasars

▪ Gaia

∆DOR (Delta-Differential One-Way Range)


State of the Art


Deep Space Tracking Stations

New Norcia

Cebreros

Malargüe

Canberra

Goldstone

Madrid

Usuda

UchinouraByalalu

13

NASA Deep Space Network and non-NASA


State of the Art


1 nanoradian @ 1

astronomical unit ≅ 150 m

• For current landing on

Mars, need accuracies ~

100 m

Atmospheric winds lead to

comparable variations

during (parachute) descent

• In outer Solar System,

higher accuracies

desirable

E.g., kilometer-scale

precision navigation

required to probe

Enceladus plumes (Saturnian moon @ 10 au)

15

right

ascension a

declination d

R

Deep Space Navigation

3. Fly the Trajectory: Toward the Future


3. Fly the Trajectory: Toward

the Future

ICRF3 X-band

Defining

ICRF3 K-band

ICRF3 Ka-band

International Celestial

Reference Frame – Third

Realization (ICRF3)

➢ Notable factor – multi-

wavelength coverage: S-

X (legacy), K, X-Ka

• S-X under increasing

threat from radio

spectrum use

• K- and Ka-band are

growth for deep space

telecommunications

➢ Beyond ICRF3

• Southern Hemisphere

• Ecliptic+

• Increasing Wavelength

Coverage

Reference Frame Development

New Norcia

Cebreros

Malargüe

Canberra

Goldstone

Madrid

Usuda

UchinouraByalalu

17

VLBA(ngVLA)


3. Toward the Future: Beyond the ICRF3

ICRF3 Ka-bandInternational Celestial Reference Frame –

Third Realization (ICRF3)

Southern Hemisphere

➢ Global coverage required for

accuracy and stability

➢ VLBA is northern hemisphere, deep-

space tracking has

notable southern

hemisphere coverage


3. Toward the Future: Beyond the ICRF3

ICRF3 Ka-band

International Celestial Reference

Frame – Third Realization (ICRF3)

Ecliptic+

➢ Global coverage required for

accuracy and stability

➢ Deep space missions

(including lunar!) have

relatively limited declination

range

Deep space tracking stations

focus on ecliptic

right

ascension a

declination d

Jupiter ca. 2029,

a la Europa

Clipper


3. Toward the Future

VLBA for Deep Space

Navigation

Possible improvements by

including the VLBA for deep

space navigation?

Mars approach example

NASA stations only: —

and —

NASA stations + VLBA

antennas: — and — Martin-Mur & Highsmith, “Mars Approach

Navigation Using the VLBA”


Summary

1. Positions and Physical Models of Celestial Bodies


3. Fly the TrajectoryIncludes VLBI and Celestial Reference Frame

Toward the Future: Beyond ICRF3

Southern Hemisphere

Ecliptic+VLBA for Deep Space Navigation?

4. High precision dynamic and measurement models

[T. Ely et al., “Comparison of Deep Space Navigation using Optical

Imaging, Pulsar Time-of-Arrival Tracking, and/or Radiometric

Tracking,” Acta Astronautica, submitted]

Backup Material


Current Deep Space Navigation Data Types

• Radio metric observations are based on light-time.

– Usually multiplied by speed to light to express as distance

– Accuracy of clocks at stations often limit accuracy

• Doppler measures rate of change of light time (velocity).

– Measurement precision is ~(l/1000)/100 s ~ 3 µm/100 s ~ 0.3 µm/s ~ c/1015

– Accuracy usually limited by solar plasma, ionosphere, or troposphere

– High accuracy of Doppler is essential for estimation of force models.

• Range measures absolute light time (1-way or 2-way).

– Radio uses group delay of modulation with accuracy ~ 1 m.

• 2-way range usually used; 1-way range requires much better clock accuracy

• Better accuracy not helpful, since transverse components much less well known

• VLBI or ∆DOR (delta-differenced one-way range)

– Measure difference of arrival time of signal from spacecraft at two stations

• ∆t/c divided by distance between stations, gives angular measure.

• Quasars (natural radio sources) used to calibrate difference in station clocks.


Orbit Error Components for Cruise

• Transverse position and velocity inferred from

– Time history of Doppler (signature from Earth rotation)

Singular for zero declination

– Difference in range measurements

Limited by station clock calibration to ~ 30 nanoradian

• VLBI/∆DOR measures transverse position directly.

Use of natural radio source as timing calibration signal enables accuracy

< 1 nanoradian

Range

r

z

y

x

Declination

Right Ascension

! Radial

! Declination

! Right Ascension

Spacecraft PositionUncertainty Ellipsoid

• For cruise, need to estimate

spacecraft position and velocity

as function of time

• Radial (to Earth) position and

velocity measured directly by

range and Doppler

6/14/15 IPPW-15 - Navigation 25

Sample X-band Doppler Residuals

• DSN Doppler files can be integrated to show actual measured

changes in range.

– Unknown constant bias must be estimated.

• Missing or deleted points complicate the integration.

– Require either correction for missing cycles or estimation of additional bias.

• Sample shown is at SEP ~ 90°, so limited by wet troposphere noise.


Looking Ahead – Mission Concepts

Technology Infusion:• Deep Space Atomic Clock – to reduce DSN tracking needs

• Low-Thrust / Low-Energy Trajectories – to increase mass delivery

• Onboard Optical and Radio Navigation - to enable pinpoint landing and

autonomous operations

UH

F A

nte

nna

Cam

era

X-B

and P

atch

Arra

y

IRIS

Radio

C

&D

H E

lectro

nics

EP

S E

lectro

nics

Sta

r Tra

cker &

AC

S E

lectro

nics

MM

A H

aW

K

Sola

r Panels

Additio

nal

Sola

r Panel

AC

S C

old

Gas

(hid

den)

Batte

ries

AC

S R

WA (3

x)

(hid

den)


Determine Natural Body Physical Models

Lunar

Gravity

Map

• Pole Orientations

• Spin Rates

• Shape Models

• Gravity Fields

Often needed for flight operations prior to availability from science team

Mars

Gravity

Map

Phobos Orientation

Vesta Shape Model


Find ‘Global Minima’

Complex constraints

complicate the initial

search…

State of the art

techniques are used to

uncover exceptionally

strong trajectory

solutions…Launch Date

Arr

ival

Date

Pork Chop

Plot

Not always straightforward


International Partnerships

ISRO Mars Orbiter

(Ongoing)

JAXA Hayabusa-2 Asteroid

Sample Return (2014-2020)

ESA Rosetta

Comet Rendezvous/Landing (2014)ESA Mars Express (2003)

Mars Orbit Insertion

JAXA Hayabusa-1 Comet Sample Return

(2010) Earth Return

http://airborne.seti.org/hayabusa/images/CCO-postflight.mp4


Entry Point Targeting

NASA Deep Space Entry/Re-Entry Experiences

Earth:

– Genesis (2004 direct entry)

– Stardust (2006 direct entry)

Mars:

– Viking 1,2 (1976 from orbit)

– Mars Pathfinder (1997 direct entry)

– Mars Exploration Rovers (2004 direct entry)

– Phoenix Mars Lander (2008 direct entry)

– Mars Science Laboratory (2012 direct entry)

Jupiter:

– Galileo (2003 from orbit)

Titan:

– Cassini-ESA/Huygens (2005 from Saturn orbit)


Deep Space Navigation Components

• Deep Space Navigation refers to orbit determination & prediction,

and maneuver design to reach desired target at desired time.

– Target orbit/position is usually estimated in advance separately, but

sometimes improved with navigation data.

• Tracking data used from Earth observatories.

– Primarily done with antennas of the Deep Space Network (DSN) located in

Goldstone (CA), Madrid (Spain), and Canberra (Australia).

– Occasionally augmented by stations in Japan (ISAS), Australia, and

Argentina (ESA).

• Navigation phases include; cruise, planetary orbit, satellite tour.

– Cruise generally has weakest observation geometry.

• Most demanding performance to date is direct landing on Mars (MSL).

– Planetary orbiters generally have larger dynamical signature.

– Satellite tour (e.g. Galileo, Cassini) geometrically in-between

• Satellite orbit determination often requires spacecraft-based imaging


Next Generation Mars Entry

Descent and Landing

TECHNOLOGY #1

Terrain Relative

Navigation (TRN)

TECHNOLOGY #2

Guidance for Fuel Optimal

Large Diverts (G-FOLD)

MSLPin-Point

(future)

Multi-

Point

(proposed for

M2020)

image

landmarks landing ellipse

TECHNOLOGY #3

Hazard Detection &

Avoidance

AutoNav

On July 4, 2005, AutoNav

enabled the third of NASA’s

first three comet nuclei

missions (at left); the other

two being:

Borrelly, Sept 2001,

Wild 2, Nov. 2002, both also

captured with AutoNav.

These were followed by

Hartley2 in 2010, and a

Tempel 1 revisit in 2011.

AutoNav placed optical

navigation elements onboard

for otherwise impossible

speedy turn-around of

navigation operations.


Deep Space Navigation - NASA

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