Communication and Navigation System

Doro Gracia

Kazuya Suzuki

Patrick Zeitouni

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Mission Requirements

Provide adequate communication between: Rovers Emergency transfer vehicles Bases and waypoints

Provide adequate navigation capability for: lunar landers rovers along race route

Establish: communications and navigation infrastructure.

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Comm Requirements & Issues

High data rates from rovers: 4 active HDTV channels 12 Mbps per rover

Continuous Rover coverage From lunar equator to pole trek

Rovers Limitations: Power limited, Earth-Moon distance at that data rate cannot be achieved Antenna Pointing accuracy a problem during race (bounce) Complex antennas like phased arrays can solve pointing

problem, but are expensive, bulky, and are even more power inefficient

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Lunar Com Options Trade Study Looked at laser and radio frequencies (RF) communication

Straight to Earth / Earth orbiting satellites Through Lunar orbiting satellites

Looked at surface towers Chose LC to Earth Orbit for Bases & Waypoints Chose RF to Lunar Orbit for Rovers

Link Closure Pointing Complexity

Link Closure Pointing Complexity

Link Closure Pointing Complexity Costs

Lunar Satellite Good Bad OK Good Good OK Good Good OK OKEarth Satellite Good Bad OK Good OK OK Good Good Good OKLunar Satellite Good Good OK Good Good OK Good Good OK OKEarth Satellite Bad Bad Good Bad Good Good Bad Good Good OKLunar Satellite Good Good Bad Good Good OK Good Good OK BadEarth Satellite Good Good Bad Good Good Good Good Good Good Bad

Good OK Bad Good OK Bad N/A N/A N/A Good

Waypoints Bases

LaserCom

RF

Phased ArraySurface Towers

Rover

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

LC

RF

GEO

Rover Com SystemGEO satellites either advanced TDRSS or commercial satellite equipped with optical head

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Rovers have a 0.3m antenna Rovers communicate to Lunar orbit

Adequate link margin Relaxed pointing requirement

Satellite Constellation 0.6m Antenna to Lunar surface, LC back to Earth 4 satellites in 2 repeating ground track orbits

Inclined (85~90) to service poles Eccentric (0.6) to dwell longer in south pole Satellite pairs spaced 180° apart in same orbit to provide handoff

Rover Com System Details

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Satellite Orbits

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Rover Coverage

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

LCRF

GEO

Base & Waypoint Com System

Given their fixed locations, bases and waypoints communicate directly to Earth orbit using LC

GEO satellites either advanced TDRSS or commercial satellite equipped with optical head

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Earth-Moon Phase Transport Com Satellite based system with RF com capabilities

for: Communications

between crew transport and Earth between crew transport and L1 station depending on

proximity < 55,000km. Use a 1m antenna (adequate dB margin)

L1 Station

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

TV Programming

TV studios from Earth gateways provide live rover race feed (via satellites)

Continuous 24 hours a day coverage Daily summaries with highlights of events Pay-per-view provides:

In-depth analysis behind the scenes And more

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Navigation Mission Requirements

Provide navigation capabilities for the following: Lunar landings (manned & unmanned) Rovers Rescue missions

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Available Options

Satellites Towers Beacons Inertial systems Image Terrain Navigation (landmarks)

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Landing navigation at bases Beacons (like existing airports)

Rover navigation Image terrain navigation for rovers

Backup guidance for rovers Inertial systems, recalibrated at waypoints Earth assistance

Proposed Systems

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Emergency vehicle navigation Track the beacons on rovers

Beacons at Waypoints Assist in emergency or other landings

RF Buoys dropped by rovers Establish a route that future rovers can

follow Assist in emergency landings

Proposed Systems

2-Dec-04 USC 2004 AME 557 Space Exploration Architecture

Communication Link BudgetMargin = Rover_EIRP - Space Loss + Sat_G/T - DR - Eb -K

Design Frequency = 30 GHz (Ka-Band) - High gain, high capacity and no atmospheric loss on Moon.Waveform = QPSK - Simple, power efficient, no bandwidth constraints.Power: Transmitter Power = 100Watts Antenna Size = ?

Space Loss: Max Range 55,000km = 217dB

Satellite G/T: Amtemma size - 0.6m dish = 45dB EOC = 42dB Receiver Elect. Temp. = -28dB 14dB/k

Data Rate: 3Mb X 4 Active Channels = 12Mbs = 10Log(12) = 73dBEb/No (Waveform Dependent) = 4.8dBK (Boltzmann's Const.): -228dB

1dB = EIRP - 217 - 14 - 73 - 4.8 + 228EIRP = 53.8dB

100Watts = 20dBw - Based on 10Log(100W)

Antenna Gain = EIRP - Power = 53.8 - 20 = 33.8 dBw

0.6m 42dB

0.3m 36dB - This closes with data rates.

Rover Antenna Size = 0.3m with a gain of 36dB - 2dB Ouput Loss = 34dB

TX Power Antenna Gain

Rang

Antenna Gain Receive

Boltzmann’s