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MARSats

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The MARSats would comprise the second part of the Mars Network. The MARSats would be much like the very high-bandwidth geostationary communications satellites in Earth orbit, except that they would be in a similar type of orbit around Mars. While the MARSats might not serve any specific navigation function, they would provide a breakthrough increase in connectivity and data rate. This increase would come from two factors, respectively: the MARSat's orbit and the type of telecommunications equipment it would use for both the in situ and long-haul communications links. As discussed earlier, the MARSats would be in areostationary orbits that would keep them continuously in view of and in contact with the same hemisphere of Mars (except when interrupted by infrequent eclipses). This continuous contact time potentially would enable the collection of huge volumes of data from the exploration elements.

The second factor, the type of telecommunications equipment, drives MARSat's high bandwidth. MARSat would be using a high-power, very high frequency Ka-band transceiver and a large, high-gain, dish antenna to provide a high capacity, long-haul data link to the Earth. For in situ communication with the Mars exploration elements, MARSat would employ a high-power, high-frequency X-band transceiver and pointable, high-gain, dish antenna - as well as one or more smaller spot antennas. To the extent that the exploration elements are also equipped with X-band transmitters or transceivers, the first MARSat's equipment would enable data rates of up to 1 megabits per second, or fast enough to allow streaming video from the exploration elements. Combined with the continuous contact time associated with the areostationary orbit, these data rates would enable orders of magnitude more data return than with the Microsats alone.

Because MARSat's high-power transceivers and high-gain antennas entail large amounts of power, volume, and mass, and because achieving an areostationary orbit requires very large propulsive maneuvers, the MARSat itself would necessarily be fairly large. Current MARSat point designs indicate kilowatt-level power requirements, with the solar array wing dimensions needed to provide such power on the order of 6 m by 2 m per wing. MARSat's mass in these designs ranges between 800 and 1000 kg. These power, volume, and mass characteristics necessarily drive the MARSAT to being a primary payload on a Delta-class launch vehicle. Hence, the development and launch costs for MARSat would be significantly greater than those associated with the Microsats. Fortunately, only two to three MARSats would be needed to provide Mars with near-continuous, high-bandwidth, global coverage. And, each MARSat would be large enough to accommodate subsystem and component redundancy sufficient to achieve a minimum operational life of 7 years - thereby reducing the frequency with which such satellites would need to be replaced. The first of these MARSats is tentatively planned for launch in 2007.

 

 

 

 Last updated: Nov. 24, 1999
  © Copyright 1999