Test of spare wheel puts Orbiter on path to recovery

June 15, 2012 By Guy Webster
NASA's Mars Odyssey spacecraft passes above Mars' south pole in this artist's concept illustration. The spacecraft has been orbiting Mars since October 24, 2001. Credit: NASA/JPL

(Phys.org) -- In a step toward returning NASA's Mars Odyssey orbiter to full service, mission controllers have tested a spare reaction wheel on the spacecraft for potential use with two other reaction wheels in adjusting and maintaining the spacecraft's orientation.

After more than 11 years of non-operational storage, the spare reaction wheel passed preliminary tests on Wednesday, June 12, spinning at up to 5,000 rotations per minute forward and backward. Odyssey engineers plan to substitute it for a reaction wheel they have assessed as no longer reliable. That wheel stuck for a few minutes last week, causing Odyssey to put itself into safe mode on June 8, Universal Time (June 7, Pacific Time). is a precautionary status with reduced activity.

"We are taking steps to assess the replacement of the troublesome wheel with the spare that Odyssey has been carrying for exactly this purpose," said Mars Odyssey Project Manager Gaylon McSmith of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "If the assessment results are positive, this will put us on a path toward resuming full use of Odyssey."

Like many other spacecraft, Odyssey uses a set of three reaction wheels to control its attitude, or which way it is facing relative to the sun, Earth or Mars. Increasing the of a reaction wheel inside the spacecraft causes the spacecraft itself to rotate in the opposite direction. The configuration in use since launch combines the effects of three wheels at right angles to each other to provide control in all directions. The orbiter carries a fourth reaction wheel skewed at angles to all three others so that it can be used as a substitute for any one of them. This spare wheel had not rotated since before Odyssey's April 7, 2001, .

Odyssey can also use thrusters to control its attitude. Reaction wheels offer the advantage of running on from the orbiter's , rather than drawing on the finite supply of thruster fuel. They also provide more precise control of pointing, which can enable higher data-rate communications through the orbiter's directional antenna.

Odyssey has worked at Mars for more than 10 years, which is longer than any other Mars mission in history. Besides conducting its own scientific observations, it serves as a communication relay for robots on the Martian surface. 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.

Explore further: One Mars Orbiter Takes First Photos of Other Orbiters

Related Stories

Mars Orbiter's Computer Reboots Successfully

March 12, 2009

(PhysOrg.com) -- NASA's Mars Odyssey orbiter properly followed commands today to shut down and restart, a strategy by its engineers to clear any memory flaws accumulated in more than five years since Odyssey's last reboot. ...

Mars Odyssey Orbiter Puts Itself Into Safe Standby

December 1, 2009

(PhysOrg.com) -- 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 ...

Recommended for you

Exiled exoplanet likely kicked out of star's neighborhood

December 1, 2015

A planet discovered last year sitting at an unusually large distance from its star - 16 times farther than Pluto is from the sun - may have been kicked out of its birthplace close to the star in a process similar to what ...

Cassini mission provides insight into Saturn

December 1, 2015

Scientists have found the first direct evidence for explosive releases of energy in Saturn's magnetic bubble using data from the Cassini spacecraft, a joint mission between NASA, the European Space Agency, and the Italian ...

Timing a sextuple quasar

December 1, 2015

Quasars are galaxies with massive black holes at their cores around which vast amounts of energy are being radiated. Indeed, so much light is emitted that the nucleus of a quasar is much brighter than the rest of the entire ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.