Neither manned landings nor short-range robotic probes such as Mars Pathfinder can explore more than a small fraction of the surface of Mars, 144 million square kilometers comprising as much surface area as all the continents and islands on Earth. Complete exploration of Mars to find or conclusively rule out important discoveries such a past or present life will require high speed low-altitude or ground-based probes such as airplanes, balloons, or high-speed rovers. These devices will need high frame-rate imaging such as digital video to explore the planet and for remote operation either by astronauts on Mars or mission control on Earth. A major limitation for transmission of video both on Mars and especially between Mars and Earth is the limited bandwidths available, currently less than 100 Kilobits/seconds between Mars and Earth when line of sight is available. One solution is to establish a network of communications satellites in Mars orbit. Even with a communications network, bandwidth will be limited, especially between Mars and Earth. A complementary approach is to develop very low bitrate video compression algorithms, e.g. VHS videotape quality at 56 Kilobits/second. Methods that may be able to achieve this such as the H.26L and MPEG-4 video coding standards, contour-based image coding, and object-based image coding are discussed, including applications and special issues on Mars and in deep space such as the high bit error rates of deep space communication links.

Computer and Communications Infrastructure