NASA's Mars Odyssey orbiter, which
has been circling the red planet for nearly eight years, needs a risky reboot
to address a long-known, potential vulnerability in its memory system.
The Odyssey
team plans to perform the operation next week.
The chief concern about the
potential memory vulnerability stems from the length of time that the
spacecraft has been exposed to the accumulated effects of the space
radiation environment since the last reboot, which occurred on Oct. 31,
2003.
As an additional benefit, the
cold-reboot procedure will demonstrate whether Odyssey's onboard backup systems
will be available should they ever be required.
"We have lost no functionality,
but there would be advantages to knowing whether the B side [backup system] is
available," said Odyssey Mission Manager Gaylon McSmith of NASA's Jet Propulsion Laboratory in Pasadena, Calif.
"We have developed a careful plan for attempting to determine that."
NASA also recently revived
its Mars Reconnaissance Orbiter after a glitch sent it into its protective
safe mode last week.
In all the years since its April 7,
2001, launch, Odyssey has not needed to use its set of spare components. The
spares are called the spacecraft's "B side," which includes an
identical set of a computer processor, navigation sensors, relay radio and
other subsystems. To use any of them, Odyssey would have to shift to all of
them at once from its primary set of components, called the "A side."
On March 21, 2007, the B side spare
of an electronic component for managing the distribution of power, called the
high-efficiency power supply, became inoperable. If it is permanently disabled,
then none of the B side is available for use. Engineers have investigated the
inoperability of the power supply and that the component can probably be made
to work properly again by rebooting the orbiter's computer, although the
memory-vulnerability issue that is the current concern is not directly related
to the March 2007 event that affected the power supply.
Odyssey is in the third two-year
extension of its mission at Mars.
Some A side
components, such as the UHF radio used for communications with spacecraft on
the surface of Mars, have worked as long as they were designed to last.
In addition to its own major
scientific discoveries and continuing studies of the planet, the Odyssey
mission has played important roles in supporting the missions of the Mars rovers Spirit and Opportunity and the Phoenix Mars Lander.
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