# The Hubble is in safe mode after losing another gyroscope



## Robert Zwilling (Oct 8, 2018)

Hubble in safe mode

The Hubble telescope started out with 6 gyroscopes. Three of them are spares. The article says it needs a minimum of 3 which is what is has been using. One of those gyros failed, so now it is down to two. The plan is to restart one of the failed gyros. I guess they shut it off when it was looking like it might fail. Without any gyros the telescope can be controlled from the ground but can't perform science operations. It should be able to operate with 2 gyros.

In 2005 NASA said new software allows Hubble to operate on 2 gyros
The gyros wear out and have definite lifetimes. When all 6 of the gyros were replaced in 2009 NASA said new programming allowed it to run on 2 gyros. It did operate on 2 gyros from 2005 until 2009 when all the gyros were replaced. 

Operating in the two gyro mode
Information from the missing third gyro is supplied from other sources.

Hubble repair history
The 2009 repairs and gyro replacement were expected to take it through 2013, the gyros made it to 2018, hopefully the revived gyro will work until someone gets back out there.

Hubble Gyroscopes
Originally it was though that the gyros were failing from oxidation of the wires inside the gyros because pressurized air was used in the gyros. The air was changed to nitrogen, which seemed to extend the life of the gyros, but they still wear out.

What's involved in fixing the Hubble telescope.
From the description of the repair routines in this article it doesn't appear that astronauts can just fly out there in a little capsule or other small craft, pop in new gyros and be on their way back to the space station or Earth.


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## Edward M. Grant (Oct 8, 2018)

If SpaceX can get their BFR flying on schedule, maybe there'd be a chance to get someone up there who could fix it. Assuming the company that made the gyros can still do so, of course.


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## tinkerdan (Oct 8, 2018)

I met and spoke with Andrew J. Feustel--one of the crew of the STS 125-- prior to the repair in 2009 and from the description both of the training and what they expected to do when repairing the Hubble telescope, it was no trivial matter and the best approach was through use of the shuttles.

It has been long enough since the last repair that it would need a lot of attention to part repair and maintenance far beyond the gyros.


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## Anthoney (Oct 8, 2018)

It's a shame we don't have a convenient, reusable space craft to send up a repair crew.


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## Edward M. Grant (Oct 9, 2018)

tinkerdan said:


> I met and spoke with Andrew J. Feustel--one of the crew of the STS 125-- prior to the repair in 2009 and from the description both of the training and what they expected to do when repairing the Hubble telescope, it was no trivial matter and the best approach was through use of the shuttles.



The problem is that the shuttle was so expensive that it would have made more sense to maintain a Hubble production line and launch a new one every few years.

Thinking more about it, if BFR does fly soon, it could potentially bring Hubble back for a refit, then launch it again. Hopefully NASA still have the spare mirror in storage...


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## Robert Zwilling (Oct 24, 2018)

Hubble telescope is working again
They had to restart the gyro a couple of times, apparently it was a bit stiff from not doing anything for a couple of years.


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