NASA MARS Odyssey Orbiter Puts Itself into Standby Safe Mode

NASA's Mars Odyssey orbiter put itself into a precautionary standby status early Friday, June 8, Universal Time (Thursday evening, Pacific Time), when the spacecraft detected unexpected characteristics in movement of one of its reaction wheels.

The spacecraft uses three of these wheels as the primary method for adjusting and maintaining its orientation. It carries a spare reaction wheel.

Odyssey's flight team is in communication with the spacecraft while planning actions in response to Odyssey entering the standby status, which is called safe mode.

"The spacecraft is safe, and information we've received from it indicates the problem is limited to a single reaction wheel," said Odyssey Mission Manager Chris Potts of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

"The path forward is evaluating the health of the reaction wheel and our options for proceeding."

Because the trigger for the incident was limited to a reaction wheel, the spacecraft did not need to completely reboot its computer, as it had in some earlier safing incidents during its record-setting decade of service at Mars. The flight team will be developing a recovery timeline in coming days.

NASA launched the Mars Odyssey spacecraft on April 7, 2001. Odyssey arrived at Mars Oct. 24, 2001.

After arrival, the spacecraft spent several months using a technique called aerobraking, which involved dipping into the Martian atmosphere to adjust its orbit. In February 2002, science operations began. Odyssey has worked at Mars longer than any other mission in history.

Besides conducting its own scientific observations, it serves as a communication relay for robots on the surface of Mars.

NASA plans to use Odyssey and the newer Mars Reconnaissance Orbiter as communication relays for the Mars Science Laboratory mission during the landing and Mars-surface operations of that mission's Curiosity rover.

NASA MARS: Odyssey Orbiter goes into Safe Standby Mode

NASA's Mars Odyssey orbiter put itself into a safe standby mode on Saturday, Nov. 28, and the team operating the spacecraft has begun implementing careful steps designed to resume Odyssey's science and relay operations within about a week.

Engineers have diagnosed the cause of the Nov. 28 event as the spacecraft's proper response to a memory error with a known source. The likely cause is an upset in the orbiter's "memory error external bus," as was the case with a similar event in June 2008.

In safe mode over the weekend, Odyssey remained in communication with ground controllers and maintained healthy temperatures and power. To clear the memory error, the team commanded Odyssey today to perform a cold reboot of the orbiter's onboard computer. The spacecraft reported that the reboot had been completed successfully.

"This event is a type we have seen before, so we have a known and tested path to resuming normal operations," said Odyssey Project Manager Philip Varghese of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Odyssey has been orbiting Mars since 2001. 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.

Until Odyssey is available again as a communications relay, Spirit and Opportunity will be operating with direct communications to and from Earth.