NASA's Mars Odyssey orbiter, already the longest-working spacecraft ever sent to Mars, has successfully switched to using its redundant computer, a system that has not been used since before its launch in 2001.
Odyssey relayed data to Earth late Sunday (Nov. 11, 2012) that it received from NASA's Opportunity rover on Mars using the orbiter's fresh "B-side" radio for UHF (ultra-high frequency) communications. In plans for this week are relays for the newest Mars rover, Curiosity, and resumption of Odyssey's own scientific observations.
"The side-swap has gone well. All the subsystems that we are using for the first time are performing as intended," said Odyssey Project Manager Gaylon McSmith of NASA's Jet Propulsion Laboratory, Pasadena, Calif.
Like many spacecraft, Odyssey carries a pair of redundant main computers, so that a backup is available if the other fails. Odyssey's "A-side" computer and "B-side" computer each have several other redundant subsystems linked to just that computer.
The Odyssey team decided to switch to the B-side computer to begin using its inertial measurement unit. This gyroscope-equipped device senses changes in the spacecraft's orientation, providing important information for control of pointing the antenna, solar arrays and instruments.
"We have been on the A side for more than 11 years. Everything on the A side still works, but the inertial measurement unit on that side has been showing signs of wearing out," said Odyssey Mission Manager Chris Potts at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We will swap to the B side on Nov. 5 so that we still have some life available in reserve on the A side."
In many potential problem situations, the Odyssey's autonomous fault-protection response would switch the spacecraft from the active side to the other side. By preserving the capability of switching back to a fully functional A side, the mission continues to have the available protection of switching sides temporarily and correcting any fixable anomaly on the B side.
"The spare inertial measurement unit is factory new, last operated on the day before launch," Potts said.
Odyssey launched April 7, 2001, began orbiting Mars on Oct. 24 of that year, began systematic science observations of Mars in early 2002, and broke the previous record for longest-working Mars probe in December 2010.
Odyssey's longevity enables continued science, including monitoring the seasonal changes on Mars from year to year, and continued relay service.
"It is testimony to the excellent design of this spacecraft and operation of this mission in partnership with Lockheed Martin that we have brand-new major components available to begin using after more than 11 years at Mars," McSmith said.