The team operating NASA's Mars Odyssey orbiter is returning the healthy spacecraft to usual activities this week after a precautionary status of reduced activity that the orbiter entered on Sept. 14.

Odyssey properly put itself into the standby "safe mode" in response to a root cause that engineers have diagnosed as the same cause as for two previous safe mode entries, in 2005 and 2006. When the onboard flight computer could not get a routine response from the system that monitors the spacecraft's orientation, a fault protection feature in the software told the flight computer to reboot and put the spacecraft into the standby status. In reality, the attitude-control task was operating just fine, but a messaging interface system got stuck, leaving the flight computer to assume the task was no longer running.

While in safe mode, Odyssey stayed in communication, with its main antenna pointed toward Earth and its solar panels facing the sun. The ground team is returning the spacecraft to full service step by step. The spacecraft is expected to point its instruments and UHF relay antenna toward Mars today (Tuesday), to resume relaying communications from the Mars rovers on Wednesday, and to resume using its own science instruments on Thursday. The rovers are communicating directly with Earth while Odyssey is unavailable for relay.

"The spacecraft reacted exactly as it was designed to for this condition," said Odyssey Mission Manager Robert Mase of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The onboard autonomy ensures that the spacecraft keeps itself in a safe state and allows time for the ground teams to respond with the established contingency procedures that were designed for these circumstances."

JPL, a division of the California Institute of Technology, manages the Mars Odyssey project for the NASA Science Mission Directorate. The orbiter reached Mars in 2001 and is partway through its second mission extension.

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