NASA engineers working to repair Hubble after gyroscope failure

Hubble Telescope put into 'safe mode' on Friday following the failure of the gyroscope

NASA is working to resume operations on the Hubble Space Telescope after one of the spacecraft's gyroscope's failed. Hubble was put into 'safe mode' on Friday in response, while NASA engineers work to try and fix the problem.

Safe mode puts the telescope into a stable configuration until ground control can correct the issue and return the mission to normal operation.

The three gyroscopes on board Hubble help to steady and point the telescope. Science operations have been suspended while it is repaired - if it can be repaired.

Built with multiple redundancies, Hubble had six new gyros installed during a Servicing Mission in 2009. While Hubble usually uses three gyros at a time for maximum efficiency, it can continue to make scientific observations with just one.

The gyro that failed had been exhibiting end-of-life behaviour for approximately a year, NASA revealed, and its failure was not unexpected.

"Two other gyros of the same type had already failed," NASA's HubbleSite said. "The remaining three gyros available for use are technically enhanced and therefore expected to have significantly longer operational lives."

Two of those enhanced gyros are currently running. Upon powering on the third enhanced gyro that had been held in reserve, analysis of spacecraft telemetry indicated that it was not performing at the level required for operations. As a result, Hubble remains in safe mode.

Staff at NASA's Goddard Space Flight Center and the Space Telescope Science Institute are currently performing analyses and tests to determine what options are available to recover the gyro to operational performance.

An Anomaly Review Board, including experts from the Hubble team, and industry familiar with the design and performance of this type of gyro, is being formed to investigate the issue and develop a recovery plan.

If the outcome of this investigation results in recovery of the malfunctioning gyro, Hubble will resume science operations in its standard three-gyro configuration.

If the outcome indicates that the gyro has become unusable, Hubble will resume science operations in an already defined 'reduced-gyro' mode that uses only one gyro.

"While reduced-gyro mode offers less sky coverage at any particular time, there is relatively limited impact on the overall scientific capabilities," NASA added.