The Hubble Space Telescope has been responsible for some of the most stunning and informative pictures of deep space since it was launched in 1990, but the telescope suffered a failure on October 5 that placed it into safe mode. Now NASA has announced that the telescope has been fixed and will return to normal operations.
The failure occurred due to a problem with one of the six gyros which measure the speed at which the spacecraft turns. The Hubble instruments had to be deactivated when the third gyro malfunctioned, which caused the telescope to have problems with turning to new directions and locking on to new targets. Fortunately, there was a backup gyro onboard the spacecraft which the NASA team was able to activate remotely. Although the backup gyro was activated the day after the failure, there were issues with the data that it was sending, as it suggested that the craft was rotating far faster than it actually was.
It took three weeks to rectify the problem with the backup gyro, during which time the NASA scientists commanded the craft to perform various turns and maneuvers, and switched the gyro between different operational modes. The scientists believe that this fixed the problem by clearing a blockage between parts inside the gyro which was causing the inaccurate readings. With the gyro operating effectively, NASA then performed more tests to ensure that the gyro was stable and installed additional safeguards should the problem arise again in the future. The gyro was recalibrated by setting the telescope to rotate to point at various locations in the sky and by instructing it to lock on to targets, all of which were performed effectively.
The last stage of fixing the telescope was reactivating the instruments which had been powered down, and checking that it was sending back data correctly. All went well, and the telescope started transmitting data back to Earth for the first time since the problem arose on October 5.
Now the gyro is running correctly and the instruments have been reactivated, so Hubble can resume its data collection, capturing beautiful images of space objects.