This particular gyro caused Hubble to enter safe mode in November after returning similar faulty readings. The team is currently working to identify potential solutions. If necessary, the spacecraft can be re-configured to operate with only one gyro, with the other remaining gyro placed in reserve . The spacecraft had six new gyros installed during the fifth and final space shuttle servicing mission in 2009. To date, three of those gyros remain operational, including the gyro currently experiencing fluctuations. Hubble uses three gyros to maximize efficiency, but could continue to make science observations with only one gyro if required.