Communication and Navigation System

1
Communication and Navigation System

• Doro Gracia
• Kazuya Suzuki
• Patrick Zeitouni

2
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.

3
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

4
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

5
Rover Com System
GEO
GEO satellites either advanced TDRSS or
commercial satellite equipped with optical head
RF
LC
6
Rover Com System Details

• 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 (8590) to service poles
• Eccentric (0.6) to dwell longer in south pole
• Satellite pairs spaced 180 apart in same orbit
  to provide handoff

7
Satellite Orbits
8
Rover Coverage
9
Base Waypoint Com System
GEO
LC
RF

• 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

10
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 lt 55,000km.
• Use a 1m antenna (adequate dB margin)

L1 Station
11
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

12
Navigation Mission Requirements

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

13
Available Options

• Satellites
• Towers
• Beacons
• Inertial systems
• Image Terrain Navigation (landmarks)

14
Proposed Systems

• 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

15
Proposed Systems

• 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

16
Communication Link Budget