A statement issued by the US space agency said that Hubble entered safe mode on Friday, October 5, after one of the three gyros currently used to position the telescope failed. Six new gyros were installed during a servicing mission in 2009, three of which have now malfunctioned. According to NASA, the latest failure was not unexpected, as the gyro “had been exhibiting end-of-life behaviour for approximately a year.” While the remaining three gyros are “technically enhanced” and should be more operationally durable than the those that have failed, just two of them 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,” NASA said in a statement.
“As a result, Hubble remains in safe mode. Staff at NASA’s Goddard Space Flight Centre 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.”
Although the space telescope is designed to function optimally with three gyros, it can still operate to a high level with just one. An Anomaly Review Board made up of members of the Hubble Team, as well as experts on the particular type of gyro, will now investigate the issue and try and get the malfunctioning unit up and running. If successful, Hubble will return to its regular scientific operations. However, if the problem cannot be solved, the mission will continue in a pre-defined ‘reduced gyro’ mode using just a single gyro.
“While reduced-gyro mode offers less sky coverage at any particular time, there is relatively limited impact on the overall scientific capabilities,” NASA said.
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