3 5 deep space communications

8/3/2019 3 5 Deep Space Communications

1/17


2/17

SSOutlook for the DSN- Preparing

for an Exciting Future

DRIVERS

Growth of proximity links and consequent bandwidth demand on

trunk-lines

Migration of Space Science Enterprise mission set into deep space

Mission plan reliance on large aperture ground stations

Evolution toward more data-intensive instruments and media

NASA missions are getting more ambitious and can

return more data than ever before.


3/17

SS8-Year View: Downlink Trends

Spacecraft Data Storage Capacity as a Function ofTime

0.0

0.11.0

10.0

100.0

1,000.0

10,000.0

2003 2007 2011GbitsofOnb

oardDataStorage

Minimum

Average

Maximum

*RadioAstron, MTO, and JIMO not included.

* Near-Earth Downlink Data Rates as a Function ofTime

0.1

1.010.0

100.0

1,000.0

10,000.0

100,000.0

2003 2007 2011DownlinkDataRate(kbps)

Minimum

Average

Maximum

*

*Excludes RadioAstron.

Spacecraft data storage trends suggest collected data

volumes will increase by 1-to-2 orders of magnitude.Near-Earth downlink rates also appear to be increasing1-to-2 orders of magnitude.

Project-Estimated Daily Data Volume as a Function

of Time

0.0

0.1

1.0

10.0

100.0

1,000.0

10,000.0

2003 2007 2011

Gbitsper

Day

Minimum

Average

Maximum

*RadioAstron, MTO, and JIMO not included.

*

Project-estimated daily data volumes also exhibit anincrease of 1-to-2 orders of magnitude.

Deep Space Downlink Data Rates as a Function of

Time

0.1

1.0

10.0

100.0

1,000.0

10,000.0

100,000.0

2003 2007 2011DownlinkDataR

ates(kbps)

Minimum

Average

Maximum

Deep space downlink rates are increasing by 1-to-2orders of magnitude as well.


4/17

SSut oo or t e current -

Requirementse.g. Maximum Supportable Rates for a Mars Orbiter/Relay Circa 2005Maximum Supportable Rates for a Mars Orbiter/Relay Circa 2005--20102010

Synthetic Aperture Radar

Data for ScienceData for Science

Data for PublicData 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 2005-2010) for linkbetween Mars S/C 2.66 AU from Earth

with 100W TWTA and 5m HGAand DSN:

34m at X-band34m at Ka-band

70m at X-band70m at Ka-band

CassiniSAR

Terra

ASTER(VNIR)

SIR-C &SRTM

(X-band)

SRTM(C-band)

Direction of IncreasingData Richness

Direction of IncreasingSense of Presence

X-SARMagellan

SAR

MGS MOC

Cassini ISS

AVIRIS

AIRSAR

Lansats4&5 TM

Landsats1,2, &3 MSS

OrbView-2

CassiniVIMS

Terra

ASTER(SWIR)

TerraASTER (TIR)

IMAX

AdequateScience

Image/min*(4bpp)

AdequatePublic

Image/min*(1bpp)

Quality

ScienceImage/min*

MPEG-1

(352x240 at30 frames/sec)

Ave. MPEG-2 (704x480

at 30 frames/sec)

ATV Standard

(Min.)

ATVStandard

(Max.)

Gen. DeliveryRate(6MHz

Channel)

12-ChannelIMP Pancam/min

(3:1 compression)

12-Channel IMPPancam/min

DATARATES(bits/s)

Raw NTSC

Studio QualityVideo (720x486

at 30 frames/sec)

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


5/17

SS Looking Toward the 20-Year Horizon: 2.7AU Mars Orbiter/Relay ScenarioSynthetic Aperture Radar

Data for ScienceData for Science

Data for PublicData 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 7ETM+

EO-1 ALI

Anticipated maximum supportabledata rate (circa 2013) for link

between Mars S/C 2.66 AU from Earthwith 100W TWTA and 5m HGA

and DSN:34m at Ka-band70m 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

Cassini ISS

AVIRIS

AIRSAR

Lansats4&5 TM

Landsats

1,2, &3 MSS

OrbView-2

CassiniVIMS

TerraASTER(SWIR)

Terra

ASTER (TIR)

IMAX

Adequate

ScienceImage/min*

(4bpp)

Adequate

PublicImage/min*

(1bpp)

Quality

ScienceImage/min*

6.8E+8 bps with200:1 compression

MPEG-1(352x240 at

30 frames/sec)

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

ATV Standard(Min.)

ATVStandard

(Max.)

Gen. Delivery

Rate(6MHzChannel)

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

12-Channel IMPPancam/min

MGS MOC

Maximum supportable optical comm data rate

at maximum Earth-Mars separation distanceassuming 10m optical telescope on ground &50cm telescope with 5W laser on S/C.

DATA

RATES(bits/s)


6/17

SS Bringing Home the Bacon

NASAs Office of Space Science is exploring two approaches:1. Optical communications

2. Enhanced RF communications


7/17

SS Optical Communication

Operational demonstration of laser comm on deep space missions will occuron the Mars Telcom Orbiter in 2009

Current design parameters:

Average laser power = 5W; 300W peak

Wavelength = 1.06 microns

Geiger Mode Avalanche Photodiodes

Target Data Rates from Mars: 3 Mbps at conjunction; 10 Mbps at opposition

Looking at beacon and beaconless pointing systems

Receive Terminals:

Ground-based: 3-9 8-10m class collecting area required [not imaging quality]

Could be accomplished with an array of 16 off the shelf telescopes or 8 1m

telescopes arrayed as well High altitude balloons

Space based data capture


8/17

SS RF Communication

Three Pronged Approach:

More Efficient Encoding of the Data on the Spacecraft

More powerful Transmitters and/or More Bandwidth on the

Downlink

Bigger Light Bucket


9/17

SS Moving Up- to Ka Band

Why Ka-band and Why Now?Deep space X-Band allocation is getting crowded

More missionsHigher telemetry rates:

Will affect spectrum availability to future missions

for many years to come

Only 50 MHz allocated. Will not increase.


10/17

SS 2007 Mars Missions Spectra, Planned Rates

Figure 1. Spectral Occupancy of Mars Missions in 2007 Time Frame (Data rates are as currently conceived by miss ions)

-30

-20

-10

0

8400 8405 8410 8415 8420 8425 8430 8435 8440 8445 8450

Frequency, MHz

RelativeP

SD,

d

Odyssey(220ksps, ch.8)Mars07Landerr (7.2 ksps)Mars07Rover (7.2 ksps)Mars Scout Orbiter(9 ksps )ME(586 ksps, ch.18)CNES07Orbiter(60 ksps)Telesat( 360 ksps)Mars05( 4.4Msps, filtered)

-Only Mars Express and Odyssey have been

assigned a frequency channel

-The center frequency (downlink) of the n th

channel is given by

8400.06 + (n-3)*1.36 MHz


11/17

SS 2007 Mars Missions Spectra, LinkSupportable Rates

Figure 2. Spectral Occupancy of Mars Missions in 2007 Time Frame (Data rates for Mars 05 Orbiter, CNES 07 Orbiter and Telesat

are maximum rates supportable at 0.6 AU range)

-30

-20

-10

0

8400 8405 8410 8415 8420 8425 8430 8435 8440 8445 8450

Frequency, MHz

Relative

PSD

,dB

Odyssey(220ksps, ch.8)Mars07Landerr (7.2 ksps)Mars07Rover (7.2 ksps)Mars Scout Orbiter(9 ksps)ME(586 ksps, ch.18)CNES Orbiter (1 Msps, QPSK)

Telesat(6.7 Msps, QPSK)Mars05(17.2 Msps, QPSK)


12/17

SS Choose Your Limitation

Two Choices:

Bandwidth Limited

Signal/Noise Limited


13/17

SSSpacecraft Radio Systems --

Ka-Band TWTA

Critical Design Review of 35W TWTA wasdelayed to accommodate needs of Mars `05mission Tube selected for flight on M`05 Expanded review will validate consistency

with flight requirements

Review held at contractor facilities TWT: Thales (Thomson) in Velizy, France

EPC: Tesat-Spacecom (Bosch SatCom) inBaknang, Germany

Draft of review material has been received atJPL -- under detail review

Contractor is continuing with TWTAdevelopment as if CDR had been passed

All indications are that TWTA development andperformance are on track

Flight qualified model delivered in Dec 02

Code S is providing funding to MRO to fly theKa band Tx as a demo

Ka-band 35W TWT

Output

Input

GunCollector

Circuit,

Tube,Helix


14/17

SSEnabling NASA Science for the Next 50 Years

The Next Generation DSN

Increase DSN telemetry capability

Provide radiometric observables for precise spacecraftnavigation

Enhance DSN science capabilities


15/17

SSOne Possible Approach:

Arrays of Small Antennas

Technology advances in a number of areas are making large arrays of smaller

antennas both feasible and affordable

Low cost, high performance parabolic antennas for satellite TV

Low cost, low noise, wide bandwidth LNAs

Low cost, reliable cryogenics

Low cost fiber optic communications

Faster computing

Large Arrays could add to the DSNs value to NASA by dramatically

increasing capabilities for spacecraft communications, navigation, and ground

based science


16/17

SS Optimum Antenna Size

Cost of Providing G/T Equivalent of

12 34m Antennas or 100 12m Antennas

Site, Software,

Engineering

Electronics Antenna

0

100,000

200,000

300,000

400,000

6 8 10 12 18 25 34Antenna Diameter, Meters

TotalCost,$K


17/17

SS Current Status of Array Studies

Design studies are underway leading to a cost review in early FY04

Reflector Manufacture

Site Selection

Overall Systems Design & Electronics

Uplink Study

3 5 deep space communications

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