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Thread: Hubble Space Telescope and Chandra X-Ray Observatory are both in safe mode.

  1. #1
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    Hubble Space Telescope and Chandra X-Ray Observatory are both in safe mode.

    "NASA addressing problems with Hubble and Chandra space telescopes"

    https://spacenews.com/nasa-addressin...ce-telescopes/

    As one group of engineers continues to diagnose a gyro problem that has sidelined the Hubble Space Telescope, another is dealing with a problem that has put operations of another large space observatory on hold.

    In a statement Oct. 12, NASA said the Chandra X-Ray Observatory entered a safe mode on the morning of Oct. 10. That safe mode interrupts scientific observations and puts the spacecraft into a stable configuration.

    NASA said the cause of the Chandra safe mode is under investigation, and could be due to a problem with one of the spacecraft’s gyroscopes. “Analysis of available data indicates the transition to safe mode was normal behavior for such an event,” the agency stated. “All systems functioned as expected and the scientific instruments are safe.”

    Chandra is one of the four original “Great Observatories” developed by NASA to perform astronomy across the electromagnetic spectrum. Chandra was launched by the shuttle in 1999 for what was originally a five-year mission, later extended to 10.

    NASA also provided an update Oct. 12 on the status of another of the Great Observatories, the Hubble Space Telescope. Hubble has been in a safe mode since Oct. 5 when one of its gyros failed and another was not “performing at the level required for operations,” the agency said Oct. 8.
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    Chandra is apparently all better
    NASA
    The cause of Chandra's safe mode on October 10 has now been understood and the Operations team has successfully returned the spacecraft to its normal pointing mode. The safe mode was caused by a glitch in one of Chandra's gyroscopes resulting in a 3-second period of bad data that in turn led the on-board computer to calculate an incorrect value for the spacecraft momentum. The erroneous momentum indication then triggered the safe mode.

    The team has completed plans to switch gyroscopes and place the gyroscope that experienced the glitch in reserve. Once configured with a series of pre-tested flight software patches, the team will return Chandra to science operations which are expected to commence by next week.
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    Scott Manley has a nice video explanation of Hubble's problems

    The Hubble space telescope is probably the most famous telescope in the world, even though technically it's not on Earth. It's been working since 1990 and has been serviced 5 times, upgrading with each visit. However on Friday one of 3 remaining gyroscopes failed leaving the spacecraft without enough gyros to perform normal spacecraft operations.

    However there are plans for this which will squeeze more life out of the spacecraft for the near future.
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    And now Hubble is getting better

    NASA took great strides last week to press into service a Hubble Space Telescope backup gyroscope (gyro) that was incorrectly returning extremely high rotation rates. The backup gyro was turned on after the spacecraft entered safe mode due to a failed gyro on Friday, Oct. 5. The rotation rates produced by the backup gyro have since reduced and are now within an expected range. Additional tests will be performed to ensure Hubble can return to science operations with this gyro.

    A gyro is a device that measures the speed at which the spacecraft is turning, and is needed to help Hubble turn and lock on to new targets.

    A wheel inside the gyro spins at a constant rate of 19,200 revolutions per minute. This wheel is mounted in a sealed cylinder, called a float, which is suspended in a thick fluid. Electricity is carried to the motor by thin wires, approximately the size of a human hair, that are immersed in the fluid. Electronics within the gyro detect very small movements of the axis of the wheel and communicate this information to Hubble’s central computer. These gyros have two modes — high and low. High mode is a coarse mode used to measure large rotation rates when the spacecraft turns across the sky from one target to the next. Low mode is a precision mode used to measure finer rotations when the spacecraft locks onto a target and needs to stay very still.

    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.

    Hubble then executed additional maneuvers to make sure that the gyro remained stable within operational limits as the spacecraft moved. The team saw no problems and continued to observe the gyro through the weekend to ensure that it remained stable.
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    Quote Originally Posted by Swift View Post
    "Help desk. Mmm. Hmm. Mmm-hmm. Have you tried turning it off, then turning it back on? Try that. It's working now? You're welcome. Thanks for calling the help desk."
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    Quote Originally Posted by Roger E. Moore View Post
    "Help desk. Mmm. Hmm. Mmm-hmm. Have you tried turning it off, then turning it back on? Try that. It's working now? You're welcome. Thanks for calling the help desk."
    Well, sending an astronaut up there to smack the side of it is no longer an option.
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    Quote Originally Posted by Swift View Post
    Well, sending an astronaut up there to smack the side of it is no longer an option.
    Alan Bean would have volunteered.

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    Quote Originally Posted by schlaugh View Post
    Alan Bean would have volunteered.
    He would have, as I suspect the entire past and current astronaut corp, if we still had a spacecraft that could get there.
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  9. #9
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    Quote Originally Posted by Swift View Post
    He would have, as I suspect the entire past and current astronaut corp, if we still had a spacecraft that could get there.
    We have that Air Force X-37B thinger, have it smack the Hubble. Robot to robot, you know.
    Last edited by Roger E. Moore; 2018-Oct-23 at 11:49 PM.
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  10. #10
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    Quote Originally Posted by Swift View Post
    He would have, as I suspect the entire past and current astronaut corp, if we still had a spacecraft that could get there.
    I was curious if there had been any thought about another servicing mission, and found a little about it. From here:

    https://www.space.com/29206-how-will...scope-die.html

    apparently it's thought that, if nothing is done, 2028 for reentry is probably the worst case but Hubble might last until 2040. In any case, NASA doesn't want to leave it to do an uncontrolled entry, so it's expected they would either send a spacecraft to drop it in a controlled fashion, raise it, or just possibly do another service mission.

    This article from early 2017:

    http://www.spaceflightinsider.com/mi...icing-mission/

    said that Trump advisers were considering a servicing mission with Dream Chaser (a mini Shuttle like spacecraft) which hasn't gone into space yet. Of course, given how long Hubble might last in space, later administrations may have time to consider it as well.

    This article:

    https://spacenews.com/op-ed-a-not-so...icing-mission/

    says that SpaceX did a very preliminary study back in 2010 about using Dragon to do a mission, either with a robot arm or EVA, and spare parts stored in the Dragon's "trunk" (a section attached to the Dragon capsule). The Dragon design has changed since then, but apparently not so much to make the idea infeasible.

    I didn't see anything about Boeing's Starliner, but wouldn't be surprised if they could do something similar to Dragon. And given how long it might stay in space, there could be other entries as well - Blue Origin maybe?

    I doubt this will be like the Space Shuttle and Skylab - there was interest in raising, servicing and crewing Skylab using the Shuttle, but it took too long to get the Shuttle launched to save Skylab In this case, though, I expect crewed spacecraft will again be available in time. But will there be sufficient interest?

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    Kepler was found today to be in sleep mode, as well.
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by George View Post
    Kepler was found today to be in sleep mode, as well.
    That's not good. I thought it was sending data home.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
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  13. #13
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    Hubble Space Telescope and Chandra X-Ray Observatory are both in safe mode.

    Apparently it did so and then went into sleep mode.

    Kepler Spacecraft Updates

    Oct. 23 - Following a successful return of data from the last observation campaign, the Kepler team commanded the spacecraft into position to begin collecting data for its next campaign.

    On Friday October 19, during a regularly scheduled spacecraft contact using NASA’s Deep Space Network, the team learned that the spacecraft had transitioned to its no-fuel-use sleep mode. The Kepler team is currently assessing the cause and evaluating possible next steps.

    Oct. 15 - The Kepler spacecraft has successfully downloaded Campaign 19 data to Earth. We are monitoring the spacecraft and will provide more information when its status has been fully assessed.

    Oct. 12 - On October 11, NASA woke up the Kepler spacecraft and maneuvered it into a stable configuration that will allow NASA to download the latest data with the least amount of fuel consumption. We are still monitoring the health of the spacecraft while working towards downloading data from Campaign 19.

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    Quote Originally Posted by schlaugh View Post
    Apparently it did so and then went into sleep mode.
    Ohthankgoodness WHEW omg that scared me.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
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  15. #15
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    And Hubble is now back to normal operations:

    https://www.nasa.gov/feature/goddard...cope-safe-mode

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