MAXIM Data Systems Command & Data Handling Space - Ground Link Ground System 19 August 1999

MAXIM Data Systems Topics lData System Recommendations lOptions and Trades lSpectrum Utilization lGround Antenna Capabilities lData System Drivers lData System Block Diagram lMass/Power Summary lOperations Concept lLink Margin Summary lCost Data lSuggested Study Areas

Recommendations for MAXIM !Detector satellite will transmit science data using S-Band to Optics Spacecraft for combined transmission to ground stations !Store data continuously & dump daily for 12 min using DSN 34M using X-Band !Total downlink data rate: 300 Kbps !Use 2:1 data compression !Use S-band for Optics/Detector transmissions !Use S-band for backup comm from DSN for both Optics & Detector

Options/Trades !Detector spacecraft to transmit telemetry to Optics spacecraft for combined relay to ground station ( vs separate links) !Less ground station time required !Smaller antenna required for Detector Spacecraft & much simpler communication system !Optics spacecraft sends recorded data vs real time !Ground costs significantly less !Allows good availability on DSN 34M system

Options/Trades !DSN 34M recommended (vs 13M commercial) !Allows hi-rate playback !Reduces contact time !Much lower cost !Proven deep space operation !13 M commercial has unproven ranging capability at 40 million Km

Spectrum Utilization ØX-band Space to Ground Link Ø(+)Uplink and downlink frequency assignments available Ø(+) More efficient than S-Band (approx 11.5 dB) Ø(+)S/C hardware is available Ø(-) Rain attenuation (approx 2 dB) ØS-band for Optics/Detector link Ø(+ ) More efficient than X-Band (omni/omni) Ø(+) Existing hardware available with modifications of frequency Rx/Tx Ø(+) Allows backup to ground if needed (UHF not readily available) ØS-Band to ground link (emergency) Ø (0) Future allocation in DSN band may be questionable

Ground Antenna Capabilities DSN 34M: !X-Band Rx/Tx !G/T = 52.4 dBi/K !EIRP = 103 dBw max(can go to 110 dBw) !S-Band Rx/Tx !G/T = 42.1 dBi/K !EIRP = 98 dBw 13M commercial: ! X-Band Rx/Tx (uplink and ranging need to be added) !G/T = 37 dBi/K !EIRP = 90 dBw !S-Band Rx/Tx !G/T = 24.5 dBi/K !EIRP = 68 dBw

MAXIM Data System Drivers lMaximum Range: 40 million KM lDaily Data Volume: 432 Mbits

MAXIM Data Systems Block Diagram

RF Communications Mass/ Power Optics Spacecraft

RF Communications Mass/ Power Detector Spacecraft

DSN 34 M BWG (Stations at Canberra, Madrid, Goldstone) MAXIM MOC MAXIM Science Data MAXIM Operations Concept Diagram MAXIM Science X-band Kbps and Ranging S-band Emergency bps S-band command and 4 Kbps Telemetry (Housekeeping/Science) Commands S-band Emergency 12 bps and 100 bps

MAXIM Operations Concept !Detector spacecraft will continuously S-Band to Optics 4 Kbps (3 Kbps science, 1 Kbps housekeeping, uncompressed) !Optics spacecraft will compress 2:1 all Detector data and 1 Kbps Optics housekeeping data !Optics spacecraft will continuously record all compressed data for playback 1/day for Kbps to DSN X-Band through 1 of 2 HGA antennas !Nominal commanding/ranging to Optics spacecraft will be done via X-Band through DSN 34M BWG !Both Optics & Detector will have S-Band low-rate command/telemetry through DSN 34M for emergency operations !Commands throughput from MOC, telemetry FTP’d from fileserver

MAXIM Link Margin Summary All links have 3 dB required performance margins All links have rate 1/2 convolutional encoding

Cost Ground systems: !DSN 1hr/day = $365k/yr x 3= $1.1M !13M 8 hr/day = $7M Optics Spacecraft: !X Band !XPDRs (2) =$2M !HGA antennas(2)= $2M !S-band !XCVR(4) = $2.8M !omni antennas(4) = $300K !C&DH = $2M

Cost(cont’d) ØDetector Spacecraft: !S-band XCVR(2)= 1.4M !omni antennas(2) = $150K

Suggested Study Areas,Use of new coding schemes (e.g. Turbo Codes),Modified frequency scheme for S-band XCVR

Acronym List lACS - Attitude Control System lACU - Antenna Control Unit lBC - Bus Controller lBWG - Beam Wave Guide lDSN - Deep Space Network lFTP - File Transfer Protocol lHGA - High Gain Antenna lHSKP - housekeeping lI/F - Interface lMOC - Mission Operations Center lRF - Radio Frequency lSSR - Solid State Recorder lXCVR - Transceiver lXPDR - Transponder