Hubble gyro problem appears fixed


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Engineers have apparently pinpointed and fixed the issue that was causing the Hubble Space Telescope’s last back up gyroscope to operate incorrectly, making it likely that the telescope will return to full normal operations shortly.

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. 16. This procedure turned the gyro off for one second, and then restarted it before the wheel spun down. The intention was to clear any faults that may have occurred during startup on Oct. 6, after the gyro had been off for more than 7.5 years. However, the resulting data showed no improvement in the gyro’s performance.

On Oct. 18, the Hubble operations team commanded a series of spacecraft maneuvers, or turns, in opposite directions to attempt to clear any blockage that may have caused the float to be off-center and produce the exceedingly high rates. During each maneuver, the gyro was switched from high mode to low mode to dislodge any blockage that may have accumulated around the float.

Following the Oct. 18 maneuvers, the team noticed a significant reduction in the high rates, allowing rates to be measured in low mode for brief periods of time. On Oct. 19, the operations team commanded Hubble to perform additional maneuvers and gyro mode switches, which appear to have cleared the issue. Gyro rates now look normal in both high and low mode.

This is wonderful news, in that it means the telescope will once again be able to point accurately enough to continue to take sharp images across the entire sky. It also highlights how close we are now to the telescope’s demise, since it no longer has a back-up gyroscope. With the next failure, which will occur eventually, Hubble will descend into one gyroscope operations, holding off its second working gyro as a backup.

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10 comments

  • born01930

    Now that some time is bought “we” should decide how much Hubble is worth. $500M? $250M? then put it out something like an X prize and have whomever wants to try to fix it get that amount. Wishful thinking I know…but that is what will drive space entrepreneurship

  • MDN

    Wishful thinking maybe, but I like the idea!

    Changing topics, a thought I’ve been meaning to post for thought and comment for awhile is that we should abandon Grand Observatory class pursuits after Webb. I still shudder thinking about the reliability risks of this platform but it’s essentially a sunk cost at this point so too late to change.

    Going forward however (WFirst etc.) I suggest that future systems should adopt a SWARM architecture where we launch MANY smaller platforms that work collectively. These would be easier to develop, faster to deploy (since you can start with just 1 or a few), more flexible scientifically as you could allocate them independently or collectively, more resilient as the loss of one or a few does not kill the entire platform, and could be upgraded incrementally as instrumentation improves.

    I’m sure there would be some downsides too (the signal to noise ratio wouldn not scale as well I suspect for instance), but just think how much easier it would have been to build and launch 36 separate mini-Webb’s, each based on a single mirror equal to 1 of the 18 segments Webb uses. I bet that could have been done for less than we’ve spent and would have been up and operating by now.

  • MDN: Your thoughts make great sense, but convince the powers-that-be in the astronomy community. They want give grand observatories that eat up lots of time and money, but give those in charge nice jobs for decades.

  • John L

    Good news! Too bad there’s nothing that can visit Hubble again and replace the gyros.

    Also good news that turning it off, then turning it back on again also works for space telescopes. Of course, sometimes you have to switch it from high mode to low mode repeatedly too.

  • mpthompson

    Seems the Hubble would be the ideal candidate for a fully robotic repair mission. In low Earth orbit the robot doesn’t have to be very intelligent as it can be remotely guided by humans, it just needs to be fairly dexterous. I don’t think that it’s realistic that a Dragon capsule could be used to refurbish the Hubble as I don’t think SpaceX has developed EVA capabilities, but it shouldn’t be too hard for a Dragon to fit a robot and spare parts in it’s trunk that could effect repairs.

  • Orion314

    I think it is time to consider a practical augmentation to the treasure of HST. I’ve pondered space telescopes since the 60’s
    How about a private amature lead enterprise . via low scale launch cost like Space X ?
    Launch a small flexible mirror segment that can , periodically , be connected like a piece of a puzzle? A telescope that can work , and yet , grow over time. The GST , i.e. The Growing Space Telescope. Imagine , a Telescope mirror miles and miles in diameter..

  • Col Beausabre

    MDN – “I still shudder thinking about the reliability risks of this platform but it’s essentially a sunk cost at this point so too late to change.”

    Sunk costs are irrelevant, just as they always are.

    https://en.wikipedia.org/wiki/Sunk_cost#Overoptimistic_probability_bias

    The question is whether the expected benefits are worth any additional expenditures.

    Orion – Good God, man, you’re advocating a return to pre-1940 science! No Big Science. No National Labs. No more CERNs. No NOAA. No NASA. PRIVATE funding of scientific research! Good lord, how would they survive without sucking off the Federal teat ?! Well, Mount Palomar was built without any government money. Who paid for Einstein (yes, he was a patent examiner, but thats what he did for the money, not research, that was his after hours hobby).

  • commodude

    Anyone who’s ever called or been tech support knows the first thing you do is reboot…

  • wayne

    Q:
    I’m under the impression, at the last servicing mission, some sort of “docking-ring” was attached to the end of the Hubble, so as to facilitate a future “controlled de-orbit,” procedure.
    Am I remembering this correctly?

  • Col Beausabre

    Commodude – No the first thing you do is plug it in

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