lecture 10.1: nasa’s deep space network: current...

Lecture 10.1:

NASA’s Deep Space Network:Current Status and the Future

Курс Лекций: «Современные Проблемы Астрономии»для студентов Государственного Астрономического Института им. П.К. Штернберга

7 февраля – 23 мая 2011

В. Г. Турышев Jet Propulsion Laboratory, California Institute of Technology

4800 Oak Grove Drive, Pasadena, CA 91009 USAГосударственный Астрономический Институт им. П.К. Штернберга

Университетский проспект, дом 13, Москва, 119991 Россия

FUTURE OF DEEP SPACE NAVIGATIONFUTURE OF DEEP SPACE NAVIGATION

Outline

• General consideration• Strategy of DSN evolution

– List of current capabilities– Future needs

• Principles of Deep Space Communications• Progress 1962-2004• Mission examples:

– Voyager mission to outer planets– Galileo to Jupiter– Cassini to Saturn– Odyssey to Mars

• Concluding Remarks

Deep Space Network

Goldstone, California

Canberra, Australia

Madrid, Spain

Goldstone, California

Future’s NASA Navigation System

Complementary, Supplementary

Data Types

Ascent Vehicles

Low-Thrust, Low-EnergyTrajectories

DSNArray

In-Situ Assets

AutonomousOptical

Navigation

Advanced Interferometric

Data Types

Formation Flying

Pinpoint Landing

Small-body Proximity

Operations


In-Situ Assets

Reference Set for Navigation Requirements (2005)

Crew Exploration Vehicle (2008, Moon in 2020, Mars in 2030)Human rating of deep space navigation capabilities, emphasis on risk-reduction; complementary and supplementary navigation methods. It will evolve to enable the human exploration of the Moon and Mars.

Lunar South Pole Sample Return (2010)Going back to the Moon after 30 years, but with more demanding requirements: landing in deep craters or at the pole; autonomous 6-DOF GNC for landing and ascent.

Mars Telecom Orbiter (2009-cancel) Demonstrating autonomous optical navigation for rendezvous; gimbaled camera; providing enhanced in-situ navigation and telecom assets.

Jupiter Icy Moons Orbiter (2015?)Low-thrust and low-energy navigation inside the Jovian system, requiring innovative trajectory optimization and automated on-board control.

Mars Sample Return (2013)Pinpoint landing, ascent GNC, Mars-orbit rendezvous and docking, first trip from Mars to Earth.

Mars Science Laboratory (2009-11)The heaviest rover ever flown to Mars; a precursor to human missions demonstrating powered, precision landing.

Titan Aerorover (2025)Autonomous atmospheric GNC in an unknown environment.

Terrestrial Planet Finder (2018?)Formation-flying at an unprecedented level of accuracy.


A Timeline of Capabilities (as seen in 2005)

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Next Generation Nav S/W

Ka-Band Interferometric

Demo

Opti-metric Ranging Demo

Low-Thrust Trajectory

Control

Mars Telecom Orbiter

Mars Reconnaissance

Orbiter JIMO

Mars Science

Lab

Mars Telecom Orbiter

Next Generation Traj. Design

ToolsAutonomous Rendezvous

Demo

Mars UHF2-way EDL

Demo

Phoenix

Mars UHF2-way EDL

Demo

Autonomous Rendezvous

Mars Sample Return


A Timeline of Capabilities (as seen in 2005)

2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030

In-Situ Network-Based

Navigation

Opti-Metric

Ranging

Advanced Autonomous

On-board Nav

Human Lunar

Missions

Next Generation

MTO

Aerorover

Planet Finder

Human Mars

Missions

Substantial Nav Infrastructure at

Mars


Performance-Enhancing Capabilities

Enhancing Capabilities

Performance Measure

Advanced Ground-

Based Radio-Metrics

Optical Systems

Software Re-Engineering

Autonomous Navigation

Advanced Frequency &

Time Systems

In-Situ Assets

Orbit control accuracy on approach, Mars & terrestrial bodies

Advanced VLBI, range,

Ka-band

Gimbaled camera, moon

tracking

High precision dynamical and measurement

models

On-board GNCusing in-situ radio, optical

High precision 1-way data Tie to target

Orbit control accuracy on approach, outer planets

Advanced VLBI, range, Ka-band

Gimbaled camera, moon

tracking


models

On-board GNC using optical

High precision 1-way data -

Orbit control accuracy, in orbit

High Precision Doppler, Ka-band

Landmark tracking


models

On-board GNC using in-situ radio, optical

High precision 1-way data

Tie to planetary reference frame

Orbit reconstruction accuracy, in orbit

High Precision Doppler, Ka-band

-


models

On-board estimation

using in-situ radio, optical



Landing accuracy on surface - Descent imager


models

On-board GNC using in-situ

radio, optical, IMU, radar, laser

- Tie to planetary reference frame

Position determination of landed vehicle

High Precision Doppler,

range, Ka-band

Landmark tracking

High precision measurement

models

On-board estimation

using in-situ radio



Key capabilities that enable

ultimate performance


Navigation Tracking-Metrics Requirements (12/2007)

Tracking Error Source (1σ Accuracy) units current

capability2010 reqt

2020 reqt

2030 reqt

Doppler/random (60s) mm/s 0.03 0.03 0.03 0.02

Doppler/systematic (60s) mm/s 0.001 0.003 0.003 0.002Range/random m 0.3 0.5 0.3 0.1

Range/systematic m 1.1 2 2 1

Angles deg 0.01 .04 .04 .04

VLBI nrad 2.5 2 1 0.5

Troposphere zenith delay cm 0.8 0.5 0.5 0.3

Ionosphere TECU 5 5 3 2

Earth orientation (real-time) cm 7 5 3 2Earth orientation (after update) cm 5 3 2 0.5

Station locations (geocentric) cm 3 2 2 1

Quasar coordinates nrad 1 1 1 0.5

Mars ephemeris nrad 2 3 2 1


Approved Mission Set: DSN Supports*

• GOES N-P (C)• NOAA N, N’ (C)• PROSEDS (C)• SOLAR-B (F)

• RADARSAT (O)

Legacy LEO• GALILEO (O)• MARS GLOBAL SURVEYOR (O)• CASSINI (O)• NOZOMI (O)• STARDUST (O)• 2001 MARS ODYSSEY (O)• GSSR (O)****• MUSES-C (C), (F per MSD)• MARS EXPRESS (C)• MARS EXPLORATION ROVERS A & B (C)• ROSETTA (C)• DEEP IMPACT (C)• MESSENGER (C)• MARS RECONNAISSANCE ORBITER (C)• DAWN (C)• MARS SCOUT (F)• MARS TELESAT (F)• MARS SCIENCE LABORATORY (F)

HEO, Lunar, L1 & L2

LEOP**

• NEW HORIZONS (F)• NEW FRONTIERS (F) (X)• GRAVITY PROBE B

(O)****• EVN (O)****• GBRA (O)****• MEGA (O)****• SIRTF (C)• KEPLER (C)• SIM (F)• VOYAGERS 1 & 2 (O)• ULYSSES (O)• STEREO A & B (C)• ORBITAL DEBRIS (O)• SPACE GEODESY (O)• DISCOVERY (F) (X)• MIDEX (F) (X)• NMP (F) (X)

DEEP SPACE***

NOTES

*~20 additional spacecraft fall under “Emergency Support Only” and are not shown.

**LEOP = Launch & Early Operations Phase; almost all DSN missions receive such support, but those listed as “LEOP” receive no other significant DSN support.

***Deep Space includes missions utilizing Earth leading and trailing orbits, since spacecraft in such orbits drift out well beyond Lagrange point distances.

****Support assumes the form of ground-based observations for mission reference ties (e.g., GP-B), VLBI co-observations, radio astronomy, solar system radar, or orbital debris.

KEY

Structure & Evolution of Universe ThemeAstronomical Search for Origins ThemeExploration of the Solar System Theme

Sun-Earth Connection ThemeCross-Theme Affiliation

Unaffiliated with Space Science Enterprise(O) = Operating (as of 4/03)(C) = Commitment to support, but not yet operating (as of 4/03)(F) = Future commitment to support anticipated (as of 4/03)(X) = Not specifically called out in Code S approved “Mission Set Database” or “Mission Set

Change Log”

• CHANDRA (O)• WMAP (O)• INTEGRAL (O)• ISTP-GEOTAIL (O)• ISTP-WIND (O)• ISTP-SOHO (O)• ISTP-POLAR (O)• ACE (O)• IMAGE (O)• IMP-8 (O)• ISTP-CLUSTER II

(O)• GENESIS (O)• LUNAR-A (F)• ST-5 (C)


Future Science Missions from the SMD Roadmaps**

• AURORAL MULTISCALE• GEOSPACE SYSTEM RESPONSE IMAGER• INTERSTELLAR PROBE• SOLAR CONNECTIONS OBSERVATORY FOR PLANETARY ENVIRONS• SOLAR POLAR IMAGER• DAYSIDE BOUNDARY LAYER CONSTELLATION• MAGNETOSPHERE-IONOSPHERE OBSERVATORY• PARTICLE ACCELERATION SOLAR ORBITER• L1-DIAMOND• MAGNETIC TRANSITION REGION PROBE• SOLAR IMAGING RADIO ARRAY• STELLAR IMAGER• SUN EARTH ENERGY CONNECTOR• SUN-HELIOSPHERE-EARTH CONSTELLATION• NEPTUNE ORBITER*• IO ELECTRODYNAMICS• MARS AERONOMY*• VENUS AERONOMY

• MAGCON• SOLAR PROBE• TELEMACHUS• IONOSPHERE

THERMOSPHERE MESOSPHERE WAVES COUPLER

• HELIOSPHERIC IMAGER AND GALACTIC OBSERVER

• RECONNECTION AND MICROSCALE

• INNER HELIOSPHERE SENTINELS

• SOLAR ORBITER• INNER MAGNETOSPHERIC

CONSTELLATION• TROPICAL ITM COUPLER

2008 20182013

• SOLAR DYNAMICS OBSERVATORY• RADIATION BELT STORM PROBES• IONOSPHERE THERMOSPHERE

STORM PROBES

SEU

ASO

ESS**

SEC***

• LISA • CONSTELLATION-X

• BLACK HOLE FINDERPROBE

• EXPLORER MISSIONS

• DARK ENERGY PROBE• EXPLORER MISSIONS

• INFLATION PROBE

2023

• BIG BANG OBSERVER• BLACK HOLE IMAGER• EXPLORER MISSIONS

• SPACE INFRARED TELESCOPE FACILITY

• KEPLER

• SPACE INTERFEROMETRY MISSION

• JAMES WEBB SPACE TELESCOPE

• EXPLORER MISSION• DISCOVERY MISSION

• TERRESTRIAL PLANET FINDER• SINGLE APERTURE FAR-

INFRARED OBSERVATORY• EXPLORER MISSION• DISCOVERY MISSION

• SPACE ULTRAVIOLET / OPTICAL TELESCOPE

• LIFE FINDER• PLANET IMAGER• EXPLORER MISSION• DISCOVERY MISSION

• SOLAR-TERRESTRIAL RELATIONS OBSERVATORY

• THEMIS• GEOSPACE ELECTRODYNAMIC

CONNECTIONS• MAGNETOSPHERIC MULTISCALE

• CINDI• TWINS• AIM

• JUPITER POLAR ORBITER*

• DEEP IMPACT• MESSENGER• DAWN• MARS SCOUT• NEW HORIZONS• MARS EXPLORATION ROVERS• MARS RECONNAISSANCE ORBITER

• GLAST• GRAVITY PROBE B• SWIFT• SPIDR• EUSO• WISE

• DISCOVERY MISSIONS• SOUTH POLE AITKEN BASIN

SAMPLE RETURN• JUPITER ICY MOONS ORBITER*• MARS SCOUTS• MARS SCIENCE LABORATORY

• DISCOVERY MISSIONS• JUPITER POLAR ORBITER/PROBES*• VENUS IN-SITU EXPLORER• COMET SURFACE SAMPLE RETURN• MARS SCOUTS• MARS LONG-LIVED LANDER NETWORK

• DISCOVERY MISSIONS• MARS SCOUTS• MARS UPPER ATMOSPHERE ORBITER*• MARS SAMPLE RETURN• EUROPA LANDER• TITAN EXPLORER• NEPTUNE ORBITER WITH PROBES*

Very Approximate Launch Epoch

Key

DSN Support Likely

DSN Support PossibleDSN Support Unlikely

*Indicates possible overlap between ESS and SEC.**ESS based on Planetary Decadal Survey + President’s

FY04 Budget ; some missions may be New Frontiers missions; some SEU & SEC missions derived from latest Explorer awards.

***Some missions may be Explorer or Discovery.


20-Year Horizon: Downlink -- 10.6 AU Titan Orbiter/Relay Scenario (Maximum Supportable Rates with RF Flight Hardware Improvements and Ka Ground Improvements

Synthetic Aperture Radar

DATARATES(bits/s)

Data for Science

Data for Public

1E+04 1E+05 1E+06 1E+07 1E+08

Planetary Images

Video

Multi-Spectral & Hyper-Spectral Imagers

HDTV

NEMO,OrbView-4,Landsat 7

ETM+

EO-1 ALI

Anticipated maximum supportabledata rate (circa 2012) for linkbetween Titan S/C 10.596 AU from Earthwith 100w TWTA and 5m HGAand DSN:

34m at Ka-band

70m at Ka-band

CassiniSAR

TerraASTER(VNIR)

SIR-C &SRTM

(X-band)SRTM

(C-band)

Direction of IncreasingData Richness

Direction of IncreasingSense of Presence

X-SARMagellan

SAR

MGS MOC

Cassini ISSAVIRIS

AIRSAR

Lansats4&5 TM

Landsats1,2, &3 MSS

OrbView-2

CassiniVIMS

Terra ASTER(SWIR)

TerraASTER (TIR)

IMAX

“Adequate”Science

Image/min*(4bpp)

“Adequate”Public

Image/min*(1bpp)

“Quality”Science

Image/min*

6.8E+8 bps with200:1 compression

Raw NTSCStudio QualityVideo (720x486at 30 frames/sec)

MPEG-1(352x240 at

30 frames/sec)

Ave. MPEG-2 (704x480at 30 frames/sec)

ATV Standard(Min.) ATV

Standard(Max.)

Gen. DeliveryRate(6MHz

Channel)

12-ChannelIMP Pancam/min(3:1 compression)

12-Channel IMPPancam/min

*Reference picture is 1024 x 1024 with 12 bit depth. Planetaryimage compression characterizations from A. Kiely and F. Pollara.

70m at Ka-bandWith 1kW TWTA onNuclear Spacecraft


Level-1 Navigation Requirements

Navigation Capability 2005 2010 2020 2030Orbit control accuracy on approach, Mars & terrestrial bodies

2kmMER

2kmMSL

1kmMSR

0.5kmCEV

Orbit control accuracy on approach, outer planets

20kmCassini

20kmCassini

2kmJIMO

10kmTitan Explorer

Orbit control accuracy, in orbit 5kmMRO

5kmMRO

1kmMSR

<1kmCEV

Orbit reconstruction accuracy, in orbit 10mMGS

10mMGS

1m radialJIMO

<1mCEV

Landing accuracy on surface 21km x 5km MER

5km x 5km MSL

25m x 25m CSSR

100m x 100mCEV

Position determination of landed vehicle 20mMER

1mMSL

1mMSR

1mCEV

Many of the navigation capabilities required for the new vision are currently available, but some newmissions have requirements that cannot be fulfilled without improving existing capabilities or developing new technologies:

– Precise and rapid trajectory optimization, determination, prediction and control for approaching, orbiting or landed assets, down to kilometers or even meters.

– Pinpoint landing to within a few tens of meters at the Moon and Mars, or meters at a small body.– Low-energy and low-thrust trajectory optimization and control, especially when orbiting the moons of gas giants.– Autonomous GNC, formation flying, small-body proximity operations, and rendezvous and docking in outer space.– Complementary and supplementary navigation assets or methods to avoid single-point failures.– Improvements in attitude knowledge & control required to accurately point narrow beams for optical communications

Current JPL Capabilities

Require PlannedTechnologies & Implementations

Require NewTechnologies


A Flexible and Capable Navigation System

Missions will choose which capabilities to use and how to use them based on requirements, risk posture, and budget

A robotic mission sampling a near-Earth object could use an optical navigation camera and a LIDAR

A Hubble repair mission may use radio-metrics and an optical camera for rendezvous and docking

A lunar rover could use just a proximity radio and lunar relay orbiters

A human mission to Mars may use redundant means to enhance human safety and reduce mission risk:− Ground-based radio-metric− Proximity radio for in-situ assets− Optical camera− Radar− IMU


Space Network – 2010 CapabilitiesFUTURE OF DEEP SPACE NAVIGATIONFUTURE OF DEEP SPACE NAVIGATION

Deep Space Network in 2010FUTURE OF DEEP SPACE NAVIGATIONFUTURE OF DEEP SPACE NAVIGATION

NASA is considering implementing a 12m antenna array designed to grow at least up to 400 antennas. This would provide an aperture equal to a 240m antenna or 120

times the capability of the current 70m X-band antenna.


Purposes of Deep Space Communications

• Tracking– To permit the dialogue between G and S/C initiate

• Commands– For the mission guide

– To alter the planned profile of the mission

– To modify the TLC system itself while technology improves

• Telemetry– Transmission of scientific and engineering data from S/C


Characteristics

• Commands Characteristics:– Low data volume

– Requirement of extremely high quality(no misunderstanding of the orders can be tolerated)

• Telemetry Characteristics:– Image telemetry

• Large volume of data

• Requirement of moderate quality

– Non-image telemetry

• Small volume of data

• Requirement of high quality


Up-link Characteristics

• Large transmitter power (up to 10 kW)

• Large transmitter antenna (up to 70 m)

• Small receiving antenna

• Non-sophisticated receiver (to be highly reliable)

• Moderate computing power (for data processing)

– Low data volume ( rate = 10 ÷ 100 bit/s )– Requirement of extremely high quality ( error probability Pe = 10‐7 )


Down-link Characteristics

• Small transmitter power (3 ÷ 30 W)

• Small transmitter antenna (1 ÷ 5 m)

• large receiving antenna (30 ÷ 70 m)

• Ultra-sophisticated receiver (reliability is not a problem)

• Ultra-high computing power (for data processing)

• Image telemetry– Low data volume ( rate = 10 ÷ 100 bit/s )– Requirement of extremely high quality ( error probability Pe = 10‐7 )

• Non‐image telemetry– Low data volume ( rate = 10 ÷ 100 bit/s )– Requirement of extremely high quality ( error probability Pe = 10‐7 )


Principle of telemetry (1)

Optimal Reception (in the absence of coding)

Optimum minimum bit error probability Pe

• Baseband signal format

– binary data sequence– is the pulse shape– is the symbol period

Σ OPTIMUMRECEIVERs(t)

n0(t) additive Gaussian noise

ân


Principles of telemetry (2)

Optimal Reception (in the absence of coding)

The bit error probability

is a decreasing function of

whereis the net received power (in watts)is Boltzmann’s constantis the noise temperature (in Kelvin)is the bit rate (in bit/s)



Evaluation of net received power

The net received power is given by



Evaluation of net received power: Mariner 10

The net received power is a very small number !



Bit rate evaluation

To assure a given Pe, a minimum S/N is required

where

with



Summary• For a reliable TLC link, e.g. Pe = 10 -3 for image telemetry,

an S/N must be assured– for uncoded transmission

– for sophisticated coded transmission

• Transmitting antenna Gain

where– is the antenna efficiency– is the antenna area– is the RF carrier frequency


Sky Noise Temperature (1)

(in the absence of atmosphere)

where


Sky Noise Temperature (2)


Concluding remarks (1)

The highest TLC performance was reached by Voyager 2 at Neptune’s on August 24, 1989 with

Absolutely the most powerful TLC system ever built !!

Potentially Galileo with the full displayed antenna and the DSN of 1995 would have a higher performance with an improvement factor of 2.


Concluding remarks (2)

• Bit rate from Jupiter (5 A.U.)

• Bit rate from Mars at minimum distance (0.38 A.U.)

• Bit rate from 1 light year (63000 A.U.)

• Bit rate from Earth geostationary orbit (38000 km)

corresponding to 64 millions of TF channels !!

What does Means 21.6 kbit/s from 30 A.U. ?

21.6 (30/5)2 = 777.6 kbit/s

21.6 (30/0.38)2 = 134.62 Mbit/s

21.6 (30/63000)2 = 4.92 mbit/s = 17.7 bit/h

3 Tbit/s


Main NASA missions to planets


Cassini Spacecraft


Beam Elementary Equations (1)

• Planar beam angle

– wavelength– diameter of TX antenna (or telescope)

• Antenna gain

• Beam diameter at distance D


Beam Elementary Equations (2)

Example (from Jupiter: D = 5 A.U.)

RF (Ka band, 30 GHz)

Optical


Optical Telecomm. from Mars


Future Science and Outreach Needs


Optical Communications Vision and Mission

• Vision:– To increase volume of space data transfer,– to enable affordable virtual presence throughout the solar

system.

• Mission:– 10-100 times higher data-rate,– 1/100 the aperture area,– less mass and less power consumption– …relative to current state-of-the-art.

Over the next 30 years to enhance the current communicationscapability (1Mbps for Mars 05) by 30 dB (3 orders of magnitude)


Beam Divergence (Frequency) Effect


Near Earth vs. Deep Space


Illustration of Pointing Requirements (for Mars)


Implementation Concepts


Multi-Telescope Reception


Coding (1)

• Source coding– PCM 5 Mbit / imagine– DPCM (1986) 1.5 Mbit / imagine 1/3– DCT (1996) 500 kbit / imagine 1/10

• Channel coding– Golay (10 dB above Shannon limit)– Reed Solomon (1986) (3.5 dB above Shannon limit) – Turbo codes (1996) (1.1 dB above Shannon limit)


Coding (2)


Coding (3)


Deep-Space Network Road Map


Ka-band Deep-Space Road Map


Optical Deep-Space Road Map


Network Capacity Road Map

Near Future Capabilities for Deep Space Navigation


Typical Data Types for Spacecraft Navigation

Data Type Characteristics Current Accuracy Typical Mission Phases

Doppler Measures line-of-sight range rate

0.03 mm/s(60s)

All. Only data type used for Mars orbiting spacecraft and for certain astronomical observatories.

Range Measures line-of-sight range ~1-2 m LEOP, cruise, approach, planetary

ephemeris updates

Angles Measures plane-of-sky position

0.17 mrad0.01 deg

LEOP, usable only in the proximity of the Earth

DDOR Measures plane-of-sky position

2.5 nrad0.14 μdeg

Cruise, approach, planetary ephemeris updates

Optical Angular resolution down to about 0.1mdeg

1.7 μrad0.1 mdeg

Approach, proximity, satellite ephemeris updates

DSN navigation is the state of the art in deep space nav technology

Earth

Sun

Radio Metric Tracking:Line of Sight: Range, Doppler

Plane of Sky: VLBI Types

Solar Torques,Thruster Firings

Guidance Commands

Observations (Doppler, Range, Interferometric, Optical)

Flight-PathOptimization

Data FitOK?

Compare

DynamicModels

Observational Models

Predicted Obs

No

Yes

Flight PathEstimation

Solar System Ephemerides

Media Calibrations

Radio Source Locs

Platform Parameters

Freq. & Timing

Trajectory Design Tools

VLBI

Weather

RadioRef

MediaModeling

GDHF/Analysis

KEOF

GPS Data

Gravity Fields

Navigation S/W

The Space Navigation Process

Solar System Ephemerides



Advanced Ground-Based Radio-MetricsAdvance ground-based radio-metric navigation capabilities:• Retain and improve interferometric techniques (plane-of-sky observables):

– Ka-band DDOR by 2005– Operational VLBA spacecraft tracking by 2008– DSN Array by 2012– Improved real-time media and platform calibrations by 2012

• Retain and improve high-precision ranging and Doppler (line-of-sight observables):– High-precision multi-frequency antenna calibration by 2008– Pseudorandom-noise coding by 2010– Improved frequency and timing systems at the DSN array by 2012– Regenerative digital range transponders by 2012

Advantages:• Improved accuracy for mission critical applications:

– Improve precision on approach of Mars by using multi-spacecraft VLBI and range– Improve precision for orbiters by using Ka-band

• Reduced use of ground antenna time for routine operations– End the reliance on long sessions of line-of-sight measurements for long-arc dynamical fits, get

instantaneous 3-D positions of spacecraftEnhanced navigation capabilities:• Orbit control accuracy on approach for terrestrial and outer planets• Orbit control accuracy in orbit• Orbit reconstruction accuracy in orbit


Advanced Frequency and Timing Systems

• Advance frequency and timing systems:– Improved frequency references for high-precision applications

• Systematic upgrades of obsolescent components of DSN’s Frequency and Timing Subsystem, including improved time and frequency systems for BWG arraying by 2006

• Improved time and frequency system for the DSN Array by 2008

– On-board USOs for 1-way tracking using ground or in-situ assets• One-way spacecraft-to-spacecraft applications by 2009 (MTO)• Multiple spacecraft per antenna for telemetry and navigation by 2005 (MGS and MRO)• On-board use of ground-to-spacecraft from a Mars beacon by 2011

• Advantages:– Reduce uplink needs, e.g. Multiple Spacecraft per Antenna– Reduce power requirements, e.g. 1-way uplink data types processed on-board– Improve accuracy of 1-way data, ground-based and in-situ

• Enhanced navigation capabilities:– Orbit control accuracy on approach for terrestrial and outer planets– Orbit control accuracy on orbit– Orbit reconstruction accuracy in orbit– Landing accuracy on surface– Position determination of landed vehicles

• Enabled mission classes:– Precision landers and rovers– Ascent vehicles– Rendezvous and docking in outer space– Missions that need to navigate autonomously


Future of the DSN: Medium to Long Term

• How to proceed with existing DSN capabilities:– Refurbish, replace (with what?), or?– How long S, move to X, and 26 GHz Ka

• X to Ka for many missions is driven by need for bandwidth (not performance)

• 26 GHz need to start using it or we will loose it for scientific missions• Optical communications

– Mars '09 Telecom Orbiter Experiment Established by NASA– Hard to predict what will follow '09

• GSFC pushing back side of TDRSS space based• Dedicated Space based more flexibility but very high cost?

– Ground based may have cost, capacity, and flexibility advantage

• Large Array– Still best candidate for affordable >10 x 70m RF based capability– Must have prototype to prove viability for cost and reliable, long life operations– Programmatic uncertainty make start date uncertain


Optical Systems

• Expand usage of optical data for trajectory determination:– Light-weight gimbaled optical camera by 2005– Opti-metric data types by 2015

• Advantages:– Enabling of close-proximity operations and autonomy, especially when the round-trip light

time to the ground would make closed-loop control impossible– Improved navigation accuracy, e.g. pinpoint landing– Complementary or supplementary data types to radio-metric data for applications that

require redundancy– Gimballing reduces sequencing conflicts with other spacecraft activities– Reduced use of ground antenna time for navigation

• Enhanced navigation capabilities:– Orbit control accuracy on approach for terrestrial and outer planets– Orbit control accuracy on orbit– Landing accuracy on surface

• Enabled mission classes:– Low energy orbit transfers– Precision landers & rovers, including proximity operations around small bodies– Rendezvous and docking in outer space– Missions that need to navigate autonomously

lecture 10.1: nasa’s deep space network: current...

Documents