NASA placed its venerable Hubble Space Telescope into a “safe mode” on Friday evening because of gyroscope problems, the space agency confirmed Monday. Although science operations are expected to resume fairly soon, the current issues raise concerns about the future of the invaluable scientific instrument.
Ground operators put the telescope into this stable configuration after one of the three active gyros that steadies and points the telescope failed. According to NASA, the gyro that failed last week had been exhibiting end-of-life behavior for about a year, and its failure was not unexpected. What happens next is a little complex and requires some explanation.
The Hubble telescope has three pairs of two gyroscopes, with each pair consisting of a primary and back-up gyroscope. Moreover, in each pair, one of the gyroscopes is of an “old” design, while the other is an “enhanced” or newer design intended to last for a longer period of time.
Source: FS – All – Science – News
Hubble Space Telescope taken offline after gyroscope failure