The Planetary Society Blog
By Emily Lakdawalla
Ten years in space -- an update
Nov. 8, 2006 | 10:10 PST | 18:10 UTC
It turns out that on its tenth anniversary in space, Mars Global Surveyor is experiencing some difficulty. It's not a disaster or anything; rather, the details of the story illuminate the careful preparations that are done to make sure that distant spacecraft don't lose contact with Earth even when they run in to problems.
As described on the JPL website, Mars Global Surveyor reported on November 2 that a motor that moves one of its solar arrays had experienced errors. Onboard software switched the spacecraft to a backup motor controller, then to a backup circuitry connection. Contact with the spacecraft lapsed on November 3 and 4; on the 5th, Earth did receive signals from the spacecraft, but the signals indicated that it had entered safe mode and was awaiting instructions from Earth. There was another lapse in contact through the 5th and on November 6. JPL engineers concluded that onboard software had initiated an activity designed to help it survive a stuck solar array: it turns the stuck array toward the Sun and rotates the rest of the spacecraft in the same direction, maintaining spacecraft power at the expense of pointing its radio antenna at Earth. So, as of yesterday, they actually were not in contact with Mars Global Surveyor, but all indications are that the spacecraft is responding as it should to the problem of a stuck solar array. We'll just have to stay tuned and see how Mars Global Surveyor soldiers through this problem.
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