NASA resets Hubble gyroscope with an old tech-support trick

Cal Jeffrey

TS Evangelist
Staff member

Earlier this month the Hubble Space Telescope’s (HST) gyroscope went haywire and stopped functioning. Engineers prepared for such a contingency by installing a backup gyro. However, after turning it on, they discovered that it was spinning too fast and was unable to keep the HST held in place.

Being that the telescope is not easily accessible, the failed gyroscopes posed a significant problem for NASA engineers on the ground. How were they to get the gyroscope functioning properly again without sending up an expensive and risky spacewalk mission — were that even possible? By executing a restart of course.

"In an attempt to correct the erroneously high rates produced by the backup gyro, the Hubble operations team executed a running restart of the gyro on Oct. 16th. This procedure turned the gyro off for one second, and then restarted it before the wheel spun down."

While that is a simple way of putting it, the process is way more complicated than that. The HST doesn't have an on/off switch. As such, the Hubble team had to command the telescope to perform maneuvers while switching the gyroscope from high-rotation to low-rotation.

“During each maneuver, the gyro was switched from high mode to low mode to dislodge any blockage that may have accumulated around the float.,” said NASA in a press release.

The maneuvers worked, and the HST’s gyro is functional once again. However, NASA still has a few more tests to conduct to be sure the backup gyroscope can function properly during normal operations. After all, it has been sitting collecting dust (so to speak) for 17 years. Engineers are optimistic that the HST will be back online soon.

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Uncle Al

TS Evangelist
Wow .... all those PhD Engineers and all it took was cycling the on/off switch ..... impressive and a LOT cheaper than flying up there and smacking the thing with one of those DOD $400 hammers!
 

mbrowne5061

TS Evangelist
Wow .... all those PhD Engineers and all it took was cycling the on/off switch ..... impressive and a LOT cheaper than flying up there and smacking the thing with one of those DOD $400 hammers!
Too be fair, they were cycling between two power switches (one for each gyro; write up didn't make this clear), while firing thrusters on a multi-billion dollar piece of hardware that has been in continuous free-fall for a couple decades, while being several hundred to several thousand miles away, all in an effort to dislodge a piece of stuck hardware - and they succeeded.

It would be as if your mechanic fixed your engine after it seized on a long road trip, all by him calling your cellphone.