1. Final Version Frank Stocklin Ron Vento Bob Summers May 17 2002 Data Systems Micro-Arcsecond Imaging Mission, Pathfinder (MAXIM-PF)

2. Final Version Data Systems Page 2 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Data Systems Topics  Ops Concept  Driving Requirements and Assumptions  Selected Configuration and Rationale  Signal Margin Summary  Component Power/Mass/Cost Summary  Risk Assessment  LASER option  Backup

3. Final Version Data Systems Page 3 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center OPS CONCEPT  HUB to Free Flyers(FF)  UHF  Coherent for ranging/ 60 Kbps duplex data transfer  CDMA  simultaneous receive of 6 FF’s  Time share transmits to 6 FF’s  may also be able to simultaneous transmit to FF’s if necessary-needs some NRE  LASER reflector FF to HUB to determine relative position  HUB to Detector  S-Band  34 kbps/5.5 Kbps using HGA’s w/omni backup  Simultaneous receive/transmit with HUB to FF  LASER reflector to determine relative position  Detector to Ground  X Band to DSN  5 Mbps/5 Kbps  15 minute dump/day

4. Final Version Data Systems Page 4 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center  Launch Date: August 2015  Mission Life: 4 years required/5 year goal  Nominal Orbit: L2 Location  Stellar pointing  One HUB S/C & 6 identical Free Flyers located in a spherical arc forming a radius of 100-500 m  50 Kbps to/from  One Detector S/C located at 20 KKM from HUB  34/5.5 Kbps to/from  Distance from HUB to FF’s must be determined  RF ranging will be course & LASER will be fine  Distance from HUB to Detector must be determined  RF ranging will be course & LASER will be fine  Formation flying  Maintained by continuous RF & LASER Data Systems Driving Requirements & Assumptions

5. Final Version Data Systems Page 5 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center  No FF inter-communications  Data Latency: None  Telemetry BER =10 -5  Selective redundancy appropriate Data Systems Driving Requirements & Assumptions

6. Final Version Data Systems Page 6 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Selected Configuration & Rationale Free Flyers  UHF selected because of ease of antenna design to minimize nulls  Transponder design from current transceiver design*  CDMA used to enable simultaneous communication with 6 FF’s  Ranging enabled by use of PN code  FF’s will compute range to HUB  60 Kbps duplex link between HUB & FF’s  Baseline approach is to time share transmissions from HUB to FF’s  Possible to design for simultaneous transmissions-needs some NRE  Laser  Used for range and position of the HUB to FF’s * Prototype will fly on STS this summer

7. Final Version Data Systems Page 7 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Selected Configuration & Rationale HUB  UHF/S-Band Transponders (2)  S-Band  2 omnis  Fixed HGA (0.3 M)  2 HPAs (10 watts)  Transmit/receive 34 kbps/5.5 kbps to/from detector (operational mode)  Transmit/receive 50 bps with detector (coarse ranging and emergency)  UHF  2 omnis (or patches)  Transmit 60 kbps to each of 6 FFs (time shared - effective rate received at each FF is 10 kbps)

8. Final Version Data Systems Page 8 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Selected Configuration & Rationale Detector  S-Band  2 transponders  2 omnis  Fixed HGA (0.3 M)  2 HPA (10 watts)  Transmit/receive 5.5kbps/34 kbps to/from HUB (operational mode)  Transmit/receive 50 bps with HUB (coarse ranging and emergency)  X-Band  2 Transponders  2 omnis  2 gimbaled HGAs (0.5 M)  Transmit/Receive 50 Kbps/5 kbps with DSN 34 M (using S/C HGA)  Transmit/Receive 50 bps/5 kbps with DSN 34 M (using S/C omni)  Ranging available

9. Final Version Data Systems Page 9 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Data Systems Selected Configuration & Rationale MOC DSN 34 M Science & Hskpg Command HUB 34M Free Flyers(6) DETECTOR LASER FF’s to HUB RF LASER HUB to DETECTOR X Band

10. Final Version Data Systems Page 10 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Selected Configuration and Rational Functional Free Flyer Block Diagram C&DH LASER CMD/TLM Multi Channel UHF transponder Hybrid Diplexer Omnis/ patches To HUB

11. Final Version Data Systems Page 11 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Selected Configuration and Rational Functional HUB Block Diagram C&DH UHF Omnis/ patches 0.3M S- Band Reflector LASER Multi CH UHF/S Band Transponder(2) CMD/TLM Diplexer Hybrid S-Band Omnis Hybrid HUB to FF communications HUB to Detector communications 6 Channels from FF’s CDMA RF Switch Diplexer To Detector 6 LASER Reflectors HPA (2)

12. Final Version Data Systems Page 12 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Selected Configuration and Rational Functional Detector Block Diagram C&DH S Band Omnis 0.5M X- Band Reflector S Band Transponder(2) CMD/TLM Diplexer Hybrid X-Band Omnis Hybrid Detector to HUB communications Detector to Ground communications RF Switch Diplexer 1 LASER Reflector RF Switch HPA (2) X Band Transponder(2) 0.3 M HGA

13. Final Version Data Systems Page 13 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Maxim_PF Signal Margins

14. Final Version Data Systems Page 14 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Power/Mass/Cost Summary Free Flyer

15. Final Version Data Systems Page 15 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Mass/Cost/Power Summary HUB

16. Final Version Data Systems Page 16 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Mass/Cost/Power Summary Detector *Includes gimbals, booms, deployment hardware ComponentPower (peak/Average)MassCost S/X-band Omni Antennas (2 each)4 kg$200K X-Band xpndr (2)42/25 watts8 kg$1.0 M S-Band xpndr (2)22/22 watts7 kg$1.0 M S-Band HPA (2)40/40 watts8 kg$1.0 M S-Band HGA (fixed)4 kg$2.0 M X-Band HGA (2) ( gimbaled) 16/1 watts24 kg *$6.0 M Hybrids, diplexers, switches, misc10 kg$500K Laser reflector Included in instruments Total120/88 watts65 kg$11.7 M

17. Final Version Data Systems Page 17 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Data Systems Cost Summary FreeFlyer (6) $0.8 M HUB $4.5 M Detector $11.7 M Ground station $2.4 M (4 years)** TOTAL$19.4 M* *Laser cost included in instruments ** Includes 1 hr pre/post pass time

18. Final Version Data Systems Page 18 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center LASER OPTION  Laser data link between the HUB and Detector  Eliminates two 0.3 M antennas  4 kg and $2 M savings on both HUB and Detector.  RF transponders and HPAs still required for coarse ranging and emergency modes  Requires 1.9 kg,and 1.9 watts on both HUB and Detector  $1 M NRE and $0.5 M per flight unit  Net difference from RF  -2.1 kg, + 2 watts, -$0.5 M (Detector-Includes all NRE)  -2.1 kg, + 2 watts, -$1.5 M (HUB) ** Exact details are given in the backup charts

19. Final Version Data Systems Page 19 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Data Systems Risk Assessment  Some NRE to make current transceiver design to transponder  Multi channel receive for HUB is an evolving capability but is not a concern for the time frame of this mission  Simultaneous transmission of 2 independent signals (HUB to FF & Detector) is also doable but should be encouraged(funded) to make it happen  Simultaneous transmission of 6 signals (HUB to FF’s) is probably doable but needs to be funded & demonstrated  Basic design is low-medium risk

20. Final Version Data Systems Page 20 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Back-Up Charts

21. Final Version Data Systems Page 21 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center UHF HUB/Freeflyer - Freeflyer/Hub 50 kbps *** DOWNLINK MARGIN CALCULATION*** GSFC C.L.A.S.S. ANALYSIS #1 DATE & TIME: 5/14/ 2 14: 9:47 PERFORMED BY: R. VENTO LINKID: MAXIM FREQUENCY: 400.0 MHz RANGE: 0.5 km MODULATION: BPSK DATA RATE: 50.000 kbps CODING: RATE 1/2 CODED BER: 1.00E-05 OMNIS AT 300 DEG 1 MILLIWATT PARAMETER VALUE REMARKS --------------------------------------------------------------------------------------------- 01. USER SPACECRAFT TRANSMITTER POWER - dBW -30.00 0.0 WATTS 02. USER SPACECRAFT PASSIVE LOSS - dB 5.00 NOTE A 03. USER SPACECRAFT ANTENNA GAIN - dBi 0.00 NOTE A 04. USER SPACECRAFT POINTING LOSS - dB 0.00 NOTE A 05. USER SPACECRAFT EIRP - dBWi -35.00 06. POLARIZATION LOSS - dB 0.30 NOTE A 07. FREE SPACE LOSS - dB 78.46 NOTE B 08. ATMOSPHERIC LOSS - dB 0.00 NOTE A 09. RAIN ATTENUATION - dB 0.00 NOTE A 10. MULTIPATH LOSS - dB 0.00 NOTE A 11. GROUND STATION ANTENNA GAIN - dB 0.00 NOTE A 12. GROUND STATION PASSIVE LOSS - dB 5.00 NOTE A 13. GROUND STATION POINTING LOSS - dB 0.00 NOTE A 14. SYSTEM NOISE TEMPERATURE - dB-DEGREES-K 24.77 NOTE A 15. GROUND STATION G/T - dB/DEGREES-K -29.77 16. BOLTZMANN'S CONSTANT - dBW/(Hz*K) -228.60 CONSTANT 17. RECEIVED CARRIER TO NOISE DENSITY - dB/Hz 85.07 18. MODULATION LOSS - dB 0.00 NOTE A 19. DATA RATE - dB-bps 46.99 NOTE A 20. DIFFERENTIAL ENCODING/DECODING LOSS - dB 0.00 NOTE A 21. USER CONSTRAINT LOSS - dB 0.00 NOTE A 22. RECEIVED Eb/No - dB 38.08 23. IMPLEMENTATION LOSS - dB 3.00 NOTE A 24. REQUIRED Eb/No - dB 4.25 NOTE B 25. REQUIRED PERFORMANCE MARGIN - dB 0.00 NOTE A 26. MARGIN - dB 30.83 * MAXI04 * Minus 7.8 dB when supporting 6 Freeflyers simultaneously

22. Final Version Data Systems Page 22 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center X-band Downlink Detector to 34M BWG 5 Mbps HGA *** DOWNLINK MARGIN CALCULATION*** GSFC C.L.A.S.S. ANALYSIS #1 DATE & TIME: 5/14/ 2 14:36:44 PERFORMED BY: R. VENTO LINKID: 11 FREQUENCY: 8475.0 MHz RANGE: 1800000.0 km MODULATION: BPSK DATA RATE: 5000.000 kbps CODING: TURBO BER: 1.00E-05 S/C 0.5 METER ANTENNA 99% AVAILABILITY PARAMETER VALUE REMARKS --------------------------------------------------------------------------------------------- 01. USER SPACECRAFT TRANSMITTER POWER - dBW 6.99 5.0 WATTS 02. USER SPACECRAFT PASSIVE LOSS - dB 3.00 NOTE A 03. USER SPACECRAFT ANTENNA GAIN - dBi 30.35 NOTE A 04. USER SPACECRAFT POINTING LOSS - dB 0.50 NOTE A 05. USER SPACECRAFT EIRP - dBWi 33.84 06. POLARIZATION LOSS - dB 0.50 NOTE A 07. FREE SPACE LOSS - dB 236.11 NOTE B 08. ATMOSPHERIC LOSS - dB 0.50 NOTE A 09. RAIN ATTENUATION - dB 1.00 NOTE A 10. MULTIPATH LOSS - dB 0.00 NOTE A 11. GROUND STATION ANTENNA GAIN - dB 68.20 NOTE A 12. GROUND STATION PASSIVE LOSS - dB 0.00 NOTE A 13. GROUND STATION POINTING LOSS - dB 0.00 NOTE A 14. SYSTEM NOISE TEMPERATURE - dB-DEGREES-K 20.79 NOTE A 15. GROUND STATION G/T - dB/DEGREES-K 47.41 16. BOLTZMANN'S CONSTANT - dBW/(Hz*K) -228.60 CONSTANT 17. RECEIVED CARRIER TO NOISE DENSITY - dB/Hz 71.74 18. MODULATION LOSS - dB 0.00 NOTE A 19. DATA RATE - dB-bps 66.99 NOTE A 20. DIFFERENTIAL ENCODING/DECODING LOSS - dB 0.00 NOTE A 21. USER CONSTRAINT LOSS - dB 0.00 NOTE A 22. RECEIVED Eb/No - dB 4.75 23. IMPLEMENTATION LOSS - dB 3.00 NOTE A 24. REQUIRED Eb/No - dB 1.00 NOTE A 25. REQUIRED PERFORMANCE MARGIN - dB 0.00 NOTE A 26. MARGIN - dB 0.75 MAXI06 NOTE A: PARAMETER VALUE FROM USER PROJECT - SUBJECT TO CHANGE NOTE B: FROM CLASS ANALYSIS IF COMPUTED

23. Final Version Data Systems Page 23 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center S-band Detector/Hub - Hub/Detector 5.5 Kbps - 34 Kbps HGAs *** DOWNLINK MARGIN CALCULATION*** GSFC C.L.A.S.S. ANALYSIS #1 DATE & TIME: 5/14/ 2 12:17:48 PERFORMED BY: R. VENTO LINKID: MAXIM FREQUENCY: 2250.0 MHz RANGE: 20000.0 km MODULATION: BPSK DATA RATE: 34.000 kbps CODING:TURBO BER: 1.00E-05 S/C ANTENNAS ARE 0.3 METERS AT 300 DEG TURBO CODES PARAMETER VALUE REMARKS ----------------------------------------------------------------------------------------------------------- 01. USER SPACECRAFT TRANSMITTER POWER - dBW 6.99 5.0 WATTS 02. USER SPACECRAFT PASSIVE LOSS - dB 3.00 03. USER SPACECRAFT ANTENNA GAIN - dBi 14.51 04. USER SPACECRAFT POINTING LOSS - dB 0.00 05. USER SPACECRAFT EIRP - dBWi 18.50 06. POLARIZATION LOSS - dB 0.30 07. FREE SPACE LOSS - dB 185.51 08. ATMOSPHERIC LOSS - dB 0.00 09. RAIN ATTENUATION - dB 0.00 10. MULTIPATH LOSS - dB 0.00 11. GROUND STATION ANTENNA GAIN - dBi 14.51 0.3 M, EFF: 55.0% 12. GROUND STATION PASSIVE LOSS - dB 0.00 13. GROUND STATION POINTING LOSS - dB 0.00 14. SYSTEM NOISE TEMPERATURE - dB-DEGREES-K 24.77 15. GROUND STATION G/T - dB/DEGREES-K -10.26 16. BOLTZMANN'S CONSTANT - dBW/(Hz*K) -228.60 CONSTANT 17. RECEIVED CARRIER TO NOISE DENSITY - dB/Hz 51.04 18. MODULATION LOSS - dB 0.00 19. DATA RATE - dB-bps 45.31 20. DIFFERENTIAL ENCODING/DECODING LOSS - dB 0.00 21. USER CONSTRAINT LOSS - dB 0.00 22. RECEIVED Eb/No - dB 5.72 23. IMPLEMENTATION LOSS - dB 3.00 24. REQUIRED Eb/No - dB 1.00 25. REQUIRED PERFORMANCE MARGIN - dB 0.00 26. MARGIN - dB 1.72 MAXI02

24. Final Version Data Systems Page 24 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center - X-Band DSN 34 M BWG to Detector 5 Kbps HGA TABLE 0.5 S/C ANTENNA UPLINK DATE & TIME: 05/14/02 15: 1:25 MAXIM PF FREQUENCY - 7200.000 MHZ GROUND ANTENNA - - - 34 BWG POWER - 0.2000 K WATTS --------------------------------------------------------------------------- PARAMETERS UNITS VALUES ESTIMATED TOLERANCES (MAX RNG: (MIN RNG: DB 1805260. KM 1800000. KM 10.0 EL) 90.0 EL) FAV ADV --------------------------------------------------------------------------- EFFECTIVE RADIATED POWER DBM 120.0 120.0 1.0 -1.0 FREE SPACE DISPERSION LOSS DB -234.7 -234.7 0.0 0.0 ATMOSPHERIC LOSS DB -0.5 0.0 0.0 0.0 POLARIZATION LOSS DB -3.0 -3.0 0.0 0.0 SPACECRAFT ANTENNA GAIN DBI 28.5 28.5 0.0 0.0 SPACECRAFT PASSIVE LOSS DB -5.0 -5.0 0.5 -0.5 MAXIMUM TOTAL RECEIVED POWER DBM -94.7 -94.2 1.1 -1.1 SPACECRAFT ANTENNA NULL DEPTH DB 0.0 0.0 0.0 0.0 MINIMUM TOTAL RECEIVED POWER DBM -94.7 -94.2 1.1 -1.1 SYSTEM NOISE DENSITY DBM/HZ -171.6 -171.6 0.0 0.0 IF NOISE BANDWIDTH( 3000.000 KHZ) DB-HZ 64.8 64.8 0.0 0.0 IF NOISE POWER DBM -106.8 -106.8 0.0 0.0 IF SNR (MIN) DB 12.1 12.6 1.1 -1.1 --------------------------------------------------------------------------- CARRIER CHANNEL ------- ------- CARRIER/TOTAL POWER DB -2.9 -2.9 0.3 -0.3 RECEIVED CARRIER POWER DBM -97.6 -97.1 1.2 -1.2 CARRIER LOOP NOISE BW( 800. HZ) DB-HZ 29.0 29.0 0.0 0.0 NOISE POWER DBM -142.6 -142.6 0.0 0.0 CARRIER/NOISE DB 45.0 45.5 1.2 -1.2 REQUIRED CARRIER/NOISE DB 15.0 15.0 0.0 0.0 AVAILABLE CARRIER MARGIN DB 30.0 30.5 1.2 -1.2 REQUIRED PERFORMANCE MARGIN DB 3.0 3.0 0.0 0.0 NET MARGIN DB 27.0 27.5 1.2 -1.2 --------------------------------------------------------------------------- COMMAND CHANNEL (PCM/PSK/PM) ------- ------- ------------ COMMAND/TOTAL POWER(MI=1.10 RAD) DB -3.5 -3.5 0.3 -0.3 RECEIVED COMMAND POWER DBM -98.2 -97.7 1.2 -1.2 PREDETECTION (PSK) NOISE BW(80.000 KHZ) DB-HZ 49.0 49.0 0.0 0.0 PREDETECTION (PSK) NOISE POWER DB -122.6 -122.6 0.0 0.0 PREDETECTION (PSK) SNR DB 24.4 24.9 1.2 -1.2 COMMAND DATA RATE ( 5.000KBPS) DB-BPS 37.0 37.0 0.0 0.0 AVAILABLE ENERGY PER BIT/NOISE DENSITY DB 36.4 36.9 1.2 -1.2 DECODER DEGRADATION DB -2.0 -2.0 0.0 0.0 REQUIRED ENERGY PER BIT/NOISE DENSITY (BER=E-5) DB 10.5 10.5 0.0 0.0 AVAILABLE COMMAND MARGIN DB 23.9 24.4 1.2 -1.2 REQUIRED PERFORMANCE MARGIN DB 3.0 3.0 0.0 0.0 NET MARGIN DB 20.9 21.4 1.2 -1.2 ---------------------------------------------------------------------------

25. Final Version Data Systems Page 25 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center *** DOWNLINK MARGIN CALCULATION*** GSFC C.L.A.S.S. ANALYSIS #1 DATE & TIME: 5/15/ 2 10:39:22 PERFORMED BY: R. VENTO LINKID: 11 FREQUENCY: 8475.0 MHz RANGE: 1800000.0 km MODULATION: BPSK DATA RATE: 5.000 kbps CODING: TURBO BER: 1.00E-05 S/C 0.5 METER ANTENNA 99% AVAILABILITY PARAMETER VALUE REMARKS --------------------------------------------------------------------------------------------- 01. USER SPACECRAFT TRANSMITTER POWER - dBW 6.99 5.0 WATTS 02. USER SPACECRAFT PASSIVE LOSS - dB 3.00 NOTE A 03. USER SPACECRAFT ANTENNA GAIN - dBi 0.00 NOTE A 04. USER SPACECRAFT POINTING LOSS - dB 0.00 NOTE A 05. USER SPACECRAFT EIRP - dBWi 3.99 06. POLARIZATION LOSS - dB 0.50 NOTE A 07. FREE SPACE LOSS - dB 236.11 NOTE B 08. ATMOSPHERIC LOSS - dB 0.50 NOTE A 09. RAIN ATTENUATION - dB 1.00 NOTE A 10. MULTIPATH LOSS - dB 0.00 NOTE A 11. GROUND STATION ANTENNA GAIN - dB 68.20 NOTE A 12. GROUND STATION PASSIVE LOSS - dB 0.00 NOTE A 13. GROUND STATION POINTING LOSS - dB 0.00 NOTE A 14. SYSTEM NOISE TEMPERATURE - dB-DEGREES-K 20.79 NOTE A 15. GROUND STATION G/T - dB/DEGREES-K 47.41 16. BOLTZMANN'S CONSTANT - dBW/(Hz*K) -228.60 CONSTANT 17. RECEIVED CARRIER TO NOISE DENSITY - dB/Hz 41.89 18. MODULATION LOSS - dB 0.00 NOTE A 19. DATA RATE - dB-bps 36.99 NOTE A 20. DIFFERENTIAL ENCODING/DECODING LOSS - dB 0.00 NOTE A 21. USER CONSTRAINT LOSS - dB 0.00 NOTE A 22. RECEIVED Eb/No - dB 4.90 23. IMPLEMENTATION LOSS - dB 3.00 NOTE A 24. REQUIRED Eb/No - dB 1.00 NOTE A 25. REQUIRED PERFORMANCE MARGIN - dB 0.00 NOTE A 26. MARGIN - dB 0.90 MAXI12 NOTE A: PARAMETER VALUE FROM USER PROJECT - SUBJECT TO CHANGE NOTE B: FROM CLASS ANALYSIS IF COMPUTED X-band Downlink Detector to 34M BWG 5 Kbps OMNI Mode

26. Final Version Data Systems Page 26 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center S-band Detector/Hub - Hub/Detector 50 bits OMNIs *** DOWNLINK MARGIN CALCULATION*** GSFC C.L.A.S.S. ANALYSIS #1 DATE & TIME: 5/15/ 2 10:29:54 PERFORMED BY: R. VENTO LINKID: MAXIM PF FREQUENCY: 2250.0 MHz RANGE: 20000.0 km MODULATION: BPSK DATA RATE: 0.050 kbps CODING: TURBO BER: 1.00E-05 PARAMETER VALUE REMARKS --------------------------------------------------------------------------------------------- 01. USER SPACECRAFT TRANSMITTER POWER - dBW 10.00 10.0 WATTS 02. USER SPACECRAFT PASSIVE LOSS - dB 5.00 NOTE A 03. USER SPACECRAFT ANTENNA GAIN - dBi 0.00 NOTE A 04. USER SPACECRAFT POINTING LOSS - dB 0.00 NOTE A 05. USER SPACECRAFT EIRP - dBWi 5.00 06. POLARIZATION LOSS - dB 0.30 NOTE A 07. FREE SPACE LOSS - dB 185.51 NOTE B 08. ATMOSPHERIC LOSS - dB 0.00 NOTE A 09. RAIN ATTENUATION - dB 0.00 NOTE A 10. MULTIPATH LOSS - dB 0.00 NOTE A 11. GROUND STATION ANTENNA GAIN - dB 0.00 NOTE A 12. GROUND STATION PASSIVE LOSS - dB 2.00 NOTE A 13. GROUND STATION POINTING LOSS - dB 0.00 NOTE A 14. SYSTEM NOISE TEMPERATURE - dB-DEGREES-K 24.77 NOTE A 15. GROUND STATION G/T - dB/DEGREES-K -26.77 16. BOLTZMANN'S CONSTANT - dBW/(Hz*K) -228.60 CONSTANT 17. RECEIVED CARRIER TO NOISE DENSITY - dB/Hz 21.02 18. MODULATION LOSS - dB 0.00 NOTE A 19. DATA RATE - dB-bps 16.99 NOTE A 20. DIFFERENTIAL ENCODING/DECODING LOSS - dB 0.00 NOTE A 21. USER CONSTRAINT LOSS - dB 0.00 NOTE A 22. RECEIVED Eb/No - dB 4.03 23. IMPLEMENTATION LOSS - dB 3.00 NOTE A 24. REQUIRED Eb/No - dB 1.00 NOTE A 25. REQUIRED PERFORMANCE MARGIN - dB 0.00 NOTE A 26. MARGIN - dB 0.03 MAXI10 NOTE A: PARAMETER VALUE FROM USER PROJECT - SUBJECT TO CHANGE NOTE B: FROM CLASS ANALYSIS IF COMPUTED

27. Final Version Data Systems Page 27 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center HUB - DETECTOR LASER COMMUNICATIONS Concept: A low power laser communications link can exploit the precision alignment of the spacecraft to provide low rate data links with simple, low power, lightweight equipment.  Assumptions:  Operates only when both spacecraft are in operational attitude.  A low bandwidth RF link is used to control Hub and Detector spacecraft positioning into the operational attitude.  Approach:  Use low power “laser pointer” technology for the transmitters.  Use a different frequency from the beacon to avoid interference.  Simplify layout by using separate optics from beacon and star tracker.  Use simple modulation without forward error correction.  Requirements:  Operate at a range of 20,000 kilometers between spacecraft.  Communicate Forward data continuously from the Detector to the Hub at 5500 bps.  Communicate Return data from continuously from the Hub to the Detector at 34,000 bps.

28. Final Version Data Systems Page 28 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center Laser communications links  Transmitters:  671 nm, 10 & 50 mW GaAs diode lasers.  500 microradian beam divergence (simple lens).  Higher power version of 5 mW “laser pointer.”  Receivers:  10 cm (4”) spacecraft telescope.  3.5 dB Implementation Loss; 2.0 dB Pointing Loss.  Limited motion gimbal.

29. Final Version Data Systems Page 29 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center WEIGHT AND POWER ESTIMATE Using parametric model and engineering estimates: Note: 10 mW transmitter will require less power (< 100 mW).

30. Final Version Data Systems Page 30 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center COST & SCHEDULE ESTIMATE COST  Based on COTS laser technology; still requires a receiver.  Assumes that fundamental R&D is completed; designs exist.  NRE to adapt existing designs to specific spacecraft: ~$1M.  Recurring engineering for flight units: $0.2M to $0.5M. SCHEDULE ESTIMATE (FLIGHT EQUIPMENT)  NRE: ~ 6-12 months  Recurring Build & Test: ~ 6-12 months

31. Final Version Data Systems Page 31 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center SUMMARY  Simple, low power “laser pointer” transmitter still requires a receiver with a telescope.  Eliminating gimbals requires precise co-alignment, though  Gimbals, if needed, can be very limited motion.  Fixed geometry of spacecraft eliminates need for “look ahead.” Therefore  Sharing the telescope for both transmit and receive could be better:  Increased transmitter gain allows smaller telescope, or  Can use even lower power lasers, and  Would allow much higher data rates.  Little impact on mass and power.  Scalability very good (either alternative) through:  Changing transmitter power (first choice up to about 100 mW).  Use coding and/or better modulation (second choice).  Increasing receiver telescope aperture (last choice).

32. Final Version Data Systems Page 32 LAI-Maxim-PF May 17.2002 Goddard Space Flight Center SHARED TELESCOPE ALTERNATIVE EXAMPLE  Reduced shared aperture to 2.5 cm.  Decreased laser power to 2 mW and 10 mW. SCALABILITY