Hubble Space Telescope Enters Safe Mode

Hubble Space Telescope (Credit: NASA)

WASHINGTON (NASA PR) — NASA is working to resume science operations of the Hubble Space Telescope after the spacecraft entered safe mode on Friday, October 5, shortly after 6:00 p.m. EDT. Hubble’s instruments still are fully operational and are expected to produce excellent science for years to come.

Hubble entered safe mode after one of the three gyroscopes (gyros) actively being used to point and steady the telescope failed. Safe mode puts the telescope into a stable configuration until ground control can correct the issue and return the mission to normal operation.

Built with multiple redundancies, Hubble had six new gyros installed during Servicing Mission-4 in 2009. Hubble usually uses three gyros at a time for maximum efficiency, but can continue to make scientific observations with just one.

The gyro that failed had been exhibiting end-of-life behavior for approximately a year, and its failure was not unexpected; two other gyros of the same type had already failed. The remaining three gyros available for use are technically enhanced and therefore expected to have significantly longer operational lives.

Two of those enhanced gyros are currently running. Upon powering on the third enhanced gyro that had been held in reserve, analysis of spacecraft telemetry indicated that it was not performing at the level required for operations. As a result, Hubble remains in safe mode. Staff at NASA’s Goddard Space Flight Center and the Space Telescope Science Institute are currently performing analyses and tests to determine what options are available  to recover the gyro to operational performance.

Science operations with Hubble have been suspended while NASA investigates the anomaly. An Anomaly Review Board, including experts from the Hubble team and industry familiar with the design and performance of this type of gyro, is being formed to investigate this issue and develop the recovery plan. If the outcome of this investigation results in recovery of the malfunctioning gyro, Hubble will resume science operations in its standard three-gyro configuration.

If the outcome indicates that the gyro is not usable, Hubble will resume science operations in an already defined “reduced-gyro” mode that uses only one gyro. While reduced-gyro mode offers less sky coverage at any particular time, there is relatively limited impact on the overall scientific capabilities.

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  • Robert G. Oler

    it is time to contract out a HST revitalization mission to private enterprise

  • Paul_Scutts

    Good point, Robert, and NASA has a brand spanking new Dragon 2 just gathering dust in a “garage” somewhere, or so I’m told. 🙂 Regards, Paul.

  • Jeff2Space

    Such a mission would be hideously expensive. I’d expect you could do it with a Dragon 2, but it lacks an airlock and I’m not sure it’s going to be “certified” for EVAs like were done with Gemini and Apollo (CSM “stand up” EVAs). You have to make sure you can open and close the hatch in vacuum as well as certify all of the systems on board for vacuum exposure during the EVA.

    Might be simpler to modify a Cygnus resupply vessel with a docking mechanism on the end to attach a Dragon 2. You’d also need a side EVA hatch so the entire Cygnus pressurized section could be used as an airlock. You’d also need an “arm” on the thing to grab Hubble and use as a work platform for the EVAs. Also need a support stand on Cygnus to attach to the aft end of Hubble once it’s captured. Lots of little things would need to be done to make this possible. And all that costs money. So it’s not just the cost of flying a Dragon 2 with a crew.

  • Steve

    Of course, one or two more Gyros might fail before you get this all together. Plus, you need to gather all of these spare parts. I assume new gyros would need to be manufactured.

  • Robert G. Oler

    the thing of it, is that while one can come up with some theories about how to do it…the thing to do in my view is to try and let commercial companies “bid” on the process and see what they come up with

    FOR INSTANCE as a short term “item” it would strike me that one of the satellite servicing platforms currently being built to have a test satellite effort in GEO could in fact be modified to serve as a replacement stabilization system for Hubble…just as they would for a GEO satellite

    another possibility would be (just throwing out ideas that I thought of while doing my bike ride here) would be to take OSC’s bus platform for the Cygnus it after all has te solar arrays on them to dock with the HST and now act as a both reboost and stabilization platform

    then you can start looking at how to involve humans…I am not sure that the basic science platforms are in trouble

  • Robert G. Oler

    see my post above, it doesnt necessarily have to be crewed

  • Jeff2Space

    From what I understand, it’s the position sensing gyros that are going bad. Hubble’s reaction wheels, and magnetorquers, are fine. So yeah, if you firmly attached a “servicing satellite” that had half a dozen new sensing gyros to the back of Hubble (I believe there is an attachment point there), you might be able to restore precise pointing without having to do any EVAs.

    The challenge would be that Hubble expects its gyros to be “wired in” to its control system. The “servicing satellite” would presumably only be able to communicate with the ground. So, you’d likely need some software updates on Hubble which would allow the ground could coordinate the data transfer.

  • redneck

    I agree with letting companies bid with a couple of restrictions.

    If bids are too high, forget it we don’t need even more money is no object programs.

    Second is to write the requirements loosely enough to allow innovation. One possibility is that a new telescope with modern materials and methods could be built and launched for less than the cobbled patch job and have more capabilities.

  • Robert G. Oler

    yes. I am not saying its “plug and play” but in my view if a contract was let to do it, private industry would respond to the challenge in unique and capable ways

  • Robert G. Oler

    yes but I am curious what folks would come up with to fix it…its worth 1/2 billion or so to “revitalize it”

  • Paul_Scutts

    It would be best to have a human in the loop, Bob, we are the most adaptable tool. Remember the first servicing of Hubble and the problem with just closing the doors? You can back it in that something will not go according to script. Regards, Paul.

  • Lee

    Maybe, maybe not. It’s been up since 1990, so the electronics that haven’t yet been replaced are pretty long in the tooth. Lots has been replaced, including all the science instruments, batteries, gyros (including those that are now failing), and smaller bus controllers. Unless you are going to develop the ability to service everything in the telescope, you’re going to find that just changing a couple of gyros isn’t going to help you much. It won’t be long until something else fails.

  • Robert G. Oler

    Unless you are going to develop the ability to service everything in
    the telescope, you’re going to find that just changing a couple of gyros
    isn’t going to help you much. It won’t be long until something else

    that is what I would do…start treating Hubble as a long term national asset and figure out a revitalization program I am still thinking about that…