During normal operation, Hubble uses three gyros to point and steady the telescope. Hubble automatically entered safe mode, which allows ground control to try to resolve the problem and resume regular operation. Hubble has six gyroscope installed. Two had already suffered the same fate, and when the agency went to fire up the last remaining gyro, it refused to work properly.
Image transmitted by Hubble
However NASA says the craft can continue to work in a “reduced-gyro” mode that only requires the one gyroscope. In this situation it won’t be able to scan as much of the sky. After a similar incident in 2003 – the other NASA’s radiotelescope, Keppler, was still able to detect exoplanets and make other important observations. The Hubble Space Telescope was first deployed to low Earth orbit in 1990 and was high valuable for scientists. The current plan, according to Dr. Rachel Osten, the deputy mission head for the observatory, is to try and revive a previously failed gyroscope to replace this new failure. That could take weeks to accomplish. The Hubble Space Telescope was last serviced in 2009 and it was expected to last until 2015 but continued to operate.