In order to resume regular scientific operations, NASA is transitioning the Hubble spacecraft to a new operational mode that was previously considered. The new mode will involve the spacecraft operating with only one gyro, while keeping another gyro available for potential future use. During Hubble’s last servicing mission in 2009, six new gyros were installed. Currently, three of those gyros are still operational, including the one experiencing issues that the team is monitoring.
While Hubble normally uses three gyros for maximum efficiency, it can still conduct scientific observations with just one gyro. NASA had actually developed this plan over 20 years ago as the optimal operational mode to extend the life of the Hubble spacecraft and enable it to continue functioning with less than three working gyros. From 2005 to 2009, Hubble operated in two-gyro mode, which is very similar to the upcoming one-gyro mode.
In 2008, a brief demonstration of one-gyro operations showed no negative impact on the quality of scientific observations. This history of successful operation with fewer gyros gives NASA confidence that Hubble will still be able to provide valuable scientific data in the new operational mode.