1. LuNet Integrated Network Architecture for Sustained Human and Robotic Exploration Gary Noreen Telecommunications Architect Communications Architecture and Research Section Jet Propulsion Laboratory (818) 354-6048 gary.k.noreen@jpl.nasa.gov

2. GKN-2March 11, 2005 LuMarsNet Agenda Lunar Telecommunications Network –Presumed Requirements –Strawman Architecture ·Ground Segment ·Space Segment ›Orbit Design ›RF Payload ·Frequency Plan Mars Telecommunications Network –Presumed Requirements –Strawman Architecture ·Ground Segment ·Space Segment ›Orbit Design ›RF Payload ·Frequency Plan –Emergency Communications

3. Integrated Network Architecture GKN-3March 11, 2005 LuMarsNet Strawman Return Link Requirements UserChannel Content # of Channels Channel Rate Total Rate Operational Base Speech210 kbps20 kbps Engineering1100 kbps Astronauts Speech410 kbps40 kbps Helmet camera4100 kbps400 kbps Engineering420 kbps80 kbps Human Transports Video21.5 Mbps3 Mbps Engineering220 kbps40 kbps Robotic Rovers Video41.5 Mbps6 Mbps Engineering420 kbps80 kbps Aggregate10 Mbps High Rate BaseHDTV120 Mbps Human Transports HDTV120 Mbps Hyperspectral Imaging1150 Mbps Robotic Rovers Radar1100 Mbps Hyperspectral Imaging1150 Mbps Aggregate440 Mbps

4. GKN-4March 11, 2005 LuMarsNet Strawman Lunar Network Architecture Terrestrial ground network to support lunar exploration –Spacecraft en route to and near the moon –Earth connection to lunar relay orbiters, lunar stations Lunar relay constellation –3 Lunar Telecom Orbiters –South Pole base –Limited far side coverage Malapert Station –Repeater on summit of Malapert Mountain near lunar South Pole

5. GKN-5March 11, 2005 LuMarsNet Terrestrial Ground Network 3 Earth complexes ~120 ° apart (DSN) Eight 12 m antennas at each complex –1 for each LTO – 3 total –1 for Malapert Station –2 for spacecraft en route & on near side of moon –2 backup Potential Terrestrial Ground Network Data Rates * Assumes the moon is within the beamwidth of the ground antenna. Spacecraft Antenna Frequency Band Return* (10 W)Forward (200W) AllocationRateAllocationRate 1 m HGA S-band2.2-2.29 GHz5.2 Mbps2.025-2.11 GHz1 Mbps X-band8.45-8.5 GHz70 Mbps7.19-7.235 GHz13 Mbps K a -band25.5-27 GHz530 MbpsN/A OmniS-band2.2-2.29 GHz12.5 kbps2.025-2.11 GHz5 kbps

6. GKN-6March 11, 2005 LuMarsNet Strawman Lunar Relay Constellation 3 Lunar Telecom Orbiters (LTO) Communications payload –15 dB UHF relay MGA –1 m diameter relay HGA –1 m diameter Earth HGA Inclined elliptical orbits –Quasi-stable –Apoapses stay in southern hemisphere –Presumed requirements: at least 2 orbiters in view of base near lunar pole all the time

7. GKN-7March 11, 2005 LuMarsNet Quasi-Stable Lunar Relay Orbits Perilune altitude 125 km to 1150 km; maximum range to pole is 11,600 km Mean pass length over pole is 10.6 hours; mean gap time 3.5 hours. Inclination between 46º and 63º Eccentricity between 0.56 and 0.72 At least two orbiters 10° or higher elevation all the time from polar base

8. GKN-8March 11, 2005 LuMarsNet 1 m relay antenna used in calculations 1.5 m relay antenna would provide performance comparable to TDRS –TDRS 4.5 m Single Access antenna –Geostationary altitude (earth): 35,000 km –Maximum LTO altitude: 11,600 km 1 m Orbiter AntennaReturn (User-to-Orbiter)Forward (Orbiter-to-User) User AntennaBandFrequencyPowerRateFrequencyPowerRate -3 dB S-band2.2-2.29 GHz 4 W10 kbps 2.025-2.11 GHz 4 W10 kbps 0.25 m 15 W1.5 Mbps25 W1.5 Mbps K a -band37-37.5 GHz35 W1 Gbps Relay Data Rates

9. GKN-9March 11, 2005 LuMarsNet One sustained human base –Mid-latitude location Other requirements assumed similar to lunar case, including customer set Big differences –Two-way light time 6.3 to 44.5 minutes –Mars-Earth range extremely high (up to 2.67 AU) – must cope with incredibly low signal levels Mars Network Strawman Requirements

10. GKN-10March 11, 2005 LuMarsNet Strawman Mars Network Architecture Terrestrial ground network to support Mars exploration –Spacecraft en route to and near Mars –Earth connection to Mars relay orbiters, Mars stations Mars relay constellation –2 Mars Communication Satellites (Comsats) –Areostationary orbits ·Partially overlapping footprints ·Human base in view of both

11. GKN-11March 11, 2005 LuMarsNet Terrestrial Ground Network for Mars Exploration 3 Earth complexes ~120 ° apart (DSN) Arrays of 12 m antennas at each complex –The DSN is planning arrays of 400 12 m antennas at each complex –Array of 10 12 m antennas = one 34 m –Array of 40 12 m antennas = one 70 m A spacecraft with a 6 m HGA and a 1 kW transmitter at maximum Mars range can send 500 Mbps to an array of 180 12 m antennas Optical may be deployed if proven viable by Mars Telecommunications Orbiter

12. GKN-12March 11, 2005 LuMarsNet Strawman Mars Comsat Constellation Mars Base Sacagawea & Pocahontas Mars communication satellites Areostationary orbits (akin to geostationary) –17,033 km altitude –Overlapping footprints at human base –Extended coverage for robotic exploration Communications payload –6 m High Gain Antenna for deep space link (Earth) – optical optional –2.2 m High Gain Antenna for proximity link (Mars)

13. GKN-13March 11, 2005 LuMarsNet Areostationary altitude: 17,033 km Geostationary altitude: 35,000 km Proximity link performance –2.2 m antenna → comparable to TDRS –7 m antenna → comparable to Thuraya Relay Data Rates THURAYA SATELLITE PHONE Antenna Band ReturnForward OrbiterUserPowerRatePowerRate 2.2 m -3 dBX35 W110 kbps10 W25 kbps 0.25 m X90 W130 Mbps30 W31 Mbps KaKa 35 W800 Mbps8 W210 Mbps

14. GKN-14March 11, 2005 LuMarsNet Emergency Deep Space Communications Robotic deep space experience –Sun-point mode in the event of an anomaly –Accept very low data rates (10 bps) More robust communications may be necessary for humans –Gemini 8: spacecraft may spin uncontrollably –Humans are likely to demand voice communications ·At least 1 kbps ·Additional engineering data to monitor humans as well as CEV Sending back 1 kbps from a spinning spacecraft near maximum Mars range is very challenging –Inadequate margin even assuming array of 400 12 m antennas on the ground and 1 kW transmitter on the spacecraft

15. GKN-15March 11, 2005 LuMarsNet Conclusions A modest network of 3 LTOs and 24 12 m ground antennas could provide continuous redundant links to human and robotic missions to the near side of the moon and to one of the poles. JPL has identified a stable orbit for the LTOs that maintains near-ideal phasing. A network of two areostationary Mars communications satellites in conjunction with large arrays of small ground antennas at Earth could provide continuous redundant links to human and robotic missions in the vicinity of a mid-latitude Martian base and receive high rate data (500 Mbps). The greatest challenge may be the provision of emergency communications services to human missions en route to Mars.