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Communication and Software

Radios Issues

One aspect of our research was to develop a reliable ground communication network, capable of transmitting real audio, video, and data from any point on Mars to all personnel and equipment. Two important constraints were power efficiency and ease of on-site repair.

Options and Solutions

Several different options were considered before the actual decision was made. We explored the development of a Global Positioning System (GPS) capable of covering the whole area of Mars targeted for exploration. Negative aspects of this option inlcuded:

It would be energy inefficient, since all equipment would have to be transmitting all the time to maintain communications.
Requiring more than just three satellites, it would be inordinantly expensive.
Current technologies are of limited capability and it is unwise to risk the principal mode of communications to unproven technology.

A second option was to use multiple surface relay stations. For a power efficient transmission, the main factor is the distance to which the signal is being transmitted. Each relay would be able to receive signals from all the equipment in radius of about 5 miles and would have enough energy to send those signals to the satellite in closer orbit and then make the connection back to the originating unit for feed-back. This option was much cheaper and reliable and much more power efficient, since the relays will be able to provide their own power and be used as signal amplifiers.

A third option was proposed by the "Robotics and Automation" team. They suggested developing not only LMRs (Little Martian Rovers, the smallest exploration units, capable of going into almost inaccessible places) but also several medium-sized rovers. These new rovers obviate the need for relays: like the main rover used to carry
astronauts on manned excursions, the medium-sized robotic rovers would have enough power to send signals to the satellites and to the main base, presuming they were within sight of the rover.

Following the third option, we chose to employ the UHF band for surface-to-surface and surface-to-satellite communications. Not only is that method energy efficient, but it requires only small antennae that are appropriate for LMR deployments.

A minor issue was the communication package for the astronauts. The technologies used nowadays for fast and high-quality communications between people are so advanced, and are improving so rapidly, that we cannot reasonably choose a "best" option so far in advance of the flight. We presume that an appropriate design will be "hard-wired" into the spacesuits used for surface excursions.

Authors: Benjamin Solish (bsolish@mit.edu) and Jordan Brayanov (jordan12@mit.edu)