It has been announced by NASA that the Mars Odyssey Orbiter spacecraft, currently in orbit around the planet Mars, has been moved to its back up Inertial Measurment Unit.  The decision was taken by engineers was after they found found that the primary inertial measurement unit was suffering degradation.

The spacecraft was launched in April 2001 and was originally envisaged to have a lifespan of only three and a half years. Despite exceeding its design life, the spacecraft continues to operate as both a science data and imaging resource and as a communications relay from the planet.  However, Mars Odyssey Orbiter has suffered a series of  major and minor anomalies during is life to date including having its Radiation Environment (MARIE) instrument knocked out in a solar storm in October 2003 and suffering a partial loss of attitude control redundancy in having one of its four reaction wheels fail in June this year.