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Data Relay Systems for a Mars
Human Base in Meridiani Planum
L. Nikulásdóttir
T. Velasco
1. Scope
2. Requirements for the Communications
3. Critical Parameters
4. Case by Case Analysis
5. Summary
6. Optical Communications
7. Conclusions
1. Scope
Scope of the Study:
• Identify the Requirements and Criticalities for Communications
with the Mars Surface
• Analyse the Main options for Mars-Earth Relay Satellite
• Identify the best Strategy for a Mars Human Base in Meridiani
Planum Base
Meridiani Planum is located close to the Equator (1.9S; 354.5E)
2. Requirements for the Communications
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Current Systems – not communication satellites
NASA Mission Mars Telecommunications Orbiter (2009)
Demanding Requirements for a Human Mission
Mars Telecommunications Orbiter, source: NASA/JPL
Mars Odissey, source: NASA/JPL
2. Requirements for the Communications
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High Data Rate Communications
High Data Volume Communications
2. Requirements for the Communications
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“Continuous” Communications - occultations
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Reliability of the System
2. Requirements for the Communications
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Missions Survey
Mission
Year / Agency
Data Rate to Earth
Mars Global Surveyor
1996 / NASA
~10kbps
Mars Odyssey
2001 / NASA
~14kbps
Mars Express
2003 / ESA
~97kbps
Mars Reconnaissance Orbiter
2005 / NASA
~200kbps
Mars Telecommunications Orbiter
2009 / NASA
~1Mbps
Data rates from Mars orbiting spacecraft to Earth.
Values are estimated for the maximum distance Earth to Mars
3. Critical Parameters for Communications
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Data Rates
BR (bps)  EIRPTX (dBm )  LPROP (dB)  Eb / N 0,required (dB)  G / TRX (dB / K )  198.6dBJ / K
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Link Visibility Mars Surface to Earth
Link Visibility Mars Surface to Relay Satellite
Link Visibility Relay Satellite to Earth
Technical Feasibility (by 2019) and Costs (Dv)
Dv req  vinc  Dvorb
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Reliability/Redundancy
vinc 
2 MARS
 v
r
4. Case by Case Analysis
Low Mars Orbit
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Used for MER through Mars
Odissey and MGS
Typically 400km – Polar/Sunsynchronous
Low Coverage (2%)
Low Data Volume
Constellations increase
performances
4. Case by Case Analysis
Medium Mars Orbit
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Increases coverage time
MTO (2009)
Higher Dv for insertion
4. Case by Case Analysis
High Elliptical Orbit
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Higher coverage
Continuous communication
possible with two satellites
Low Dv required for insertion
4. Case by Case Analysis
Areostationary Orbit
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Equivalent to Geostationary orbit for Earth
Continuous coverage of the surface
Two satellites would provide continuous link with Earth
High Dv required
Needs orbit corrections
4. Case by Case Analysis
Mars Moons
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Use of Phobos or Deimos orbiters
Performances are not very high
4. Case by Case Analysis
Mars Occultation
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The Sun or Moon is between Mars and the Earth
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Occultation by the Moon is short (28 minutes)
Occultation by the Sun can happen each approx. 2 years, and can last
up to 3 weeks
Occultation by the Sun will not occur in 2019 nor 2021
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4. Case by Case Analysis
“Trojan” Orbit
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Satellite located in L4 or L5
Earth-Sun Lagrange points
Not optimal performances,
but solves the problem of
occultation
4. Case by Case Analysis
Lagrange Points
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Use L1 and L2 Sun-Mars
Good coverage
Low data rates (high
distance from Mars orbit)
High Dv needed
5. Summary
Comments/Pro’s/Con’s
Orbit
Bit Rate
Coverage
LMO
low
low
Big Constellation needed/ Low cost / Low
performance
MMO
high
med
Constellation needed / better performances /
High cost
HEO
high
med/ high
> two S/C needed /
Low cost/
Performances are limited
Stationary
very high
high
> two S/C needed /
Best performances /
Very high cost
Trojans
med
med
For Mars occultations
6. Optical Communications
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Limitation of the RF Systems
Limitation of the Bit Rates – increasing absorption
Laser Communications are the alternative
Technical Challenges: accurate pointing, cloud and dust
attenuation, components, etc
Mars Telecommunications Orbiter – Mars Laser
Communications Demonstration (MLCD)
MTO Laser communications, source: NASA/JPL
7. Conclusions and Recommendations
• High Bit Rate and Continuous Coverage are Mandatory for a
Human Mission on Mars
• Constellation of HEO or Areostationary seems to be the best
solution. HEO is preferred for the low Dv needed for insertion
• Further Work to Optimise the Concept (Failure Recovery
Modes)
• Development of Optical Communications would be big step
forward
The end
or…
…The Beginning?