Deep Space Network. Spectrum Management Issues. Presentation to the NRC Committee on Radio Frequencies [CORF] May 14, 2003 by

Transcription

1 Deep Space Network SS Spectrum Management Issues Presentation to the NRC Committee on Radio Frequencies [CORF] May 14, 2003 by Dr. Barry Geldzahler NASA HQ Program Executive for Space Operations

2 DSN Facilities SS DSS METER GOLDSTONE JPL Ne twork Operations Control Ce nter and CTA 21, Pasadena DSS 24 DSS METER B EAM WAVEGUIDE (BWG ) CALIF ORNIA DSS METER HI -E FFICIENCY (HEF ) DSS METER DSS 26 9/02 CTT DSS 27 GOLDSTONE SPC GPS MIL 71 DSN's Merritt Is. Launch Support Facility DSS METER SPAIN MADRID DSS METER HI-EFFICIENCY (HEF) DSS METER 34 -METER B EAM WAVEGUIDE (BWG) DSS55 11/03 DSS54 MADRID SPC DSS METER GPS DSS METER DSS METER B EAM WAVEGUIDE (BWG) AUSTRALIA DSS METER HI-EFFICIENCY (HEF) DSS METER DSS METER CANBERRA SPC GPS CANBERRA

3 High Level Spectrum Concerns The Army National Training Center expansion at Fort Irwin for large-scale desert training. The Army has purchased more than 100,000 acres south/south West of Goldstone. This area is directly in the direction where our antennas track spacecraft. Army is planning to use several thousand troops, several hundred vehicle and many airplanes and helicopters in that area all with state of the art communication gears. With thousands of emitters, there is a significant potential for interference to Goldstone antennas. The interference of X-band EESS missions with X-band deep space missions. EESS missions use the MHz band and usually are very wide band (several hundred MHz). The out of band emissions of EESS missions can fall within the MHz band of deep space missions. We need to have a NASA policy directing all NASA EESS missions to filter their out of band emissions. The third issue is JWST and its options and trade-offs in using X- or Ka-band. This is an example of a bigger issue: what is the proper band for high data rate near-earth missions operating at L2.

4 Other Spectrum Issues S-Band TDRSS return link ( MHz center, 6 MHz bandwidth) - Users of this link should implement filter on their satellites to reduce coordination load to project and DSN. X-Band uplink ( MHz) - Approval of primary status (relative to the Fixed Service) is expected at WRC2003. S-Band uplink ( MHz) - Restricted by IMT2000 at Madrid. X-Band downlink ( ) - Growing congestion. A provisional SFCG guideline advocated moving high rate telemetry of deep space missions to the 32 GHz band. MRO will be the first mission to do so. More stringent guidelines may be needed in the future. S-Band downlink ( MHz) - Reduced mission requirement. 32 GHz downlink - Sharing with HDFS is being studied under ITU-R. Mars relay links - SFCG established provisional frequency assignment guidelines (SFCG 22-1). Frequency assignment to new deep space missions - SFCG assigned study responsibility to NASA/JPL - SFCG RES More bandwidth requirement expected in the future.

5 Future of the DSN at Radio Frequencies Loss of low frequencies [S-band] Move to higher frequencies [Ka- band]

6 Outlook 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 [but this may change] Evolution toward more data-intensive instruments and media NASA missions are getting more ambitious and can return more data than ever before.

7 Data Rates of Today s Instrumentation Are A Small Fraction of Tomorrow s Deluge Electromagnetic radiation carries only four kinds of information: Amplitude Phase Frequency Polarization Today s planetary studies to data generally tap only amplitude and frequency. Tomorrow s planetary studies will include synthetic aperture radar, interferometry, narrower channel hyperspectral imagers, polarimeters, and??? Data rates will reach unprecedented heights, and we must begin preparations now to capture that data

8 Outlook for the current DSN- Requirements e.g. Maximum Supportable Rates for a Mars Orbiter/Relay Circa Cassini SAR Magellan SAR Synthetic Aperture Radar AIRSAR X-SAR SIR-C & SRTM (X-band) SRTM (C-band) Data for Science Cassini ISS MGS MOC Adequate Science Image/min* (4bpp) Planetary Images Cassini VIMS Quality Science Image/min* Multi-Spectral & Hyper-Spectral Imagers OrbView-2 Terra ASTER (TIR) 12-Channel IMP Pancam/min (3:1 compression) Landsats 12-Channel IMP 1,2, &3 MSS Pancam/min AVIRIS Terra ASTER (SWIR) Lansats 4&5 TM Terra ASTER (VNIR) NEMO, OrbView-4, EO-1 ALI Landsat 7 ETM+ 1E+04 1E+05 1E+06 1E+07 1E+08 Adequate Public Image/min* (1bpp) Data for Public Direction of Increasing Sense of Presence MPEG-1 (352x240 at 30 frames/sec) Anticipated maximum supportable data rate (circa ) for link between Mars S/C 2.66 AU from Earth with 100W TWTA and 5m HGA and DSN: 34m at X-band 34m at Ka-band 70m at X-band 70m at Ka-band Ave. MPEG-2 (704x480 at 30 frames/sec) ATV Standard (Min.) Video Gen. Delivery Rate(6MHz Channel) ATV Standard (Max.) HDTV Raw NTSC Studio Quality Video (720x486 at 30 frames/sec) IMAX

9 Bringing Home the Bacon Two Approaches: Radio Frequencies Optical Communications

10 Radio Frequencies Three Pronged Approach: More Efficient Encoding of the Data on the Spacecraft We are pushing the theoretical limits of what can be accomplished in coding technologies More powerful Transmitters and/or More Bandwidth on the Downlink We are deploying more powerful, larger bandwidth transmitters Larger Ground-based Collecting Area The Next Generation Deep Space Network

11 Enabling NASA Science for the Next 50 Years The Next Generation DSN Increase DSN telemetry capability by a factor of 10^6 Provide radiometric observables for precise spacecraft navigation Enhance DSN Science capabilities

12 Need to go to Ka Band Figure 1. Spectral Occupancy of Mars Missions in 2007 Time Frame (Data rates are as currently conceived by missions) 0-10 Relative PSD, db Frequency, MHz -Only Mars Express and Odyssey have been assigned a frequency channel -The center frequency (downlink) of the n th channel is given by (n-3)*1.36 MHz 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)

13 Choose Your Limitation Two Choices: Bandwidth Limited Signal/Noise Limited

14 Spacecraft Radio Systems Ka-Band TWTA Critical Design Review of 35W TWTA was delayed to accommodate needs of Mars `05 mission 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) in Baknang, Germany Draft of review material has been received at JPL -- under detail review Contractor is continuing with TWTA development as if CDR had been passed All indications are that TWTA development and performance are on track Flight qualified model due to be delivered in Aug 02 Code S is providing funding to MRO to fly the Ka band Tx as a demo Collector Circuit, Tube, Helix Output Ka-band 35W TWT Input Gun

15 DSN Ka-band Downlink Readiness Goldstone Madrid Canberra Today: First operational DSN Ka-band 34m BWG is already on-line Goldstone DSS 25 supported 98 DS1 Ka demo Now supporting Cassini Radio Science Experiment By MRO arrival (2006): One add l 34m BWG w/ Ka-band capability at each complex DSS 26 at Goldstone DSS 55 (new BWG) at Madrid DSS 34 (upgrade) at Canberra Alternate Assets [IACG WG4]: 34m ESA dish at New Norcia, Australia 49m equivalent dish at Narrabri, Australia 34m dish at Cebreros, Spain [tied to Venus Express] New Norcia 34 Narrabri ESA New Norcia 34 Narrabri 34 DSN Ka-band Implementation Plan

16 DSN Array: Working Baseline m antennas at each of the three DSN longitudes [equivalent of a 240m antenna] Freq range 2-44 GHz Primary use X [8GHz] and Ka [32 GHz for Deep Space] The future in the radio is Ka band

17 Capturing High Rate Data Data Rate, Bits/Second 1.E+11 1.E+10 1.E+09 1.E+08 1.E+07 1.E+06 1.E+05 1.E+04 Maximum Data Rate vs Distance With 5kW DC at Spacecraft 360 x12m Ka Optical m X or 34m Ka JUPITER 10 Distance, A.U x 12m Ka MARS To capture these high data rates, need 500 MHz bandwidth of the deep space spectrum. We re looking for additional Ka band bandwidth to enable a higher science return