integrated network architecture for sustained human and robotic exploration
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Integrated Network Architecture for Sustained Human and Robotic Exploration. Gary Noreen Telecommunications Architect Communications Architecture and Research Section Jet Propulsion Laboratory (818) 354-6048 [email protected]. Lunar Telecommunications Network Presumed Requirements - PowerPoint PPT PresentationTRANSCRIPT
LuNet
Integrated Network Architecture forSustained Human and Robotic Exploration
Integrated Network Architecture forSustained Human and Robotic Exploration
Gary NoreenTelecommunications ArchitectCommunications Architecture and Research SectionJet Propulsion Laboratory(818) [email protected]
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
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GKN-3March 11, 2005 LuMarsNet
Strawman Return Link Requirements
User Channel Content# of
ChannelsChannel
RateTotal Rate
Op
era
tional
BaseSpeech 2 10 kbps 20 kbps
Engineering 1 100 kbps 100 kbps
Astronauts
Speech 4 10 kbps 40 kbps
Helmet camera 4 100 kbps 400 kbps
Engineering 4 20 kbps 80 kbps
Human Transports
Video 2 1.5 Mbps 3 Mbps
Engineering 2 20 kbps 40 kbps
Robotic Rovers
Video 4 1.5 Mbps 6 Mbps
Engineering 4 20 kbps 80 kbps
Aggregate 10 Mbps
Hig
h R
ate
Base HDTV 1 20 Mbps 20 Mbps
Human Transports
HDTV 1 20 Mbps 20 Mbps
Hyperspectral Imaging 1 150 Mbps 150 Mbps
Robotic Rovers
Radar 1 100 Mbps 100 Mbps
Hyperspectral Imaging 1 150 Mbps 150 Mbps
Aggregate 440 Mbps
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
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)
Allocation Rate Allocation Rate
1 m HGA
S-band 2.2-2.29 GHz 5.2 Mbps 2.025-2.11 GHz 1 Mbps
X-band 8.45-8.5 GHz 70 Mbps 7.19-7.235 GHz 13 Mbps
Ka-band 25.5-27 GHz 530 Mbps N/A N/A
Omni S-band 2.2-2.29 GHz 12.5 kbps 2.025-2.11 GHz 5 kbps
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
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
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 Antenna Return (User-to-Orbiter) Forward (Orbiter-to-User)
User Antenna Band Frequency Power Rate Frequency Power Rate
-3 dBS-band 2.2-2.29 GHz
4 W 10 kbps2.025-2.11 GHz
4 W 10 kbps
0.25 m15 W 1.5 Mbps 25 W 1.5 Mbps
Ka-band 37-37.5 GHz 35 W 1 Gbps
Relay Data Rates
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
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
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
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)
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
AntennaBand
Return Forward
Orbiter User Power Rate Power Rate
2.2 m
-3 dB X 35 W 110 kbps 10 W 25 kbps
0.25 mX 90 W 130 Mbps 30 W 31 Mbps
Ka 35 W 800 Mbps 8 W 210 Mbps
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
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.