Missions to Mars have been fraught with failures. So the recent successes of Mars Pathfinder, Mars Global Surveyor (MGS), and Mars Odyssey are that much sweeter. Low altitude passes of MGS around the planet—a boon to magnetics—were serendipitous and actually occurred as a result of engineering malfunction. One of the solar panels did not open fully prior to intended aerobraking to circularize the orbit at its 400 km present altitude. Therefore the mission engineers allowed an elliptical orbit to continue for more than a year. This orbit brought the spacecraft close to the planet (about 100–170 km range) for a...

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