NASA fixes the Hubble Space Telescope

With a series of forced maneuvers, NASA fixes the Hubble’s gyroscopes

The HST has been operating in space for 28 years.

Washington, Oct 23 – The Hubble Space Telescope may soon resume science operations, say NASA scientists, after resolving a technical glitch that forced the probe to enter ‘safe mode’ earlier this month.

After the telescope’s gyroscope — which helps Hubble turn and lock on to new targets — failed on October 5, NASA took great strides last week to press into service a backup gyroscope (gyro) that was incorrectly returning extremely high rotation rates, according to a statement.

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, NASA said.

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 October 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 October 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.

The Hubble operations team commanded a series of spacecraft maneuver, 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.

On October 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, NASA said.

The Hubble operations team plans to execute a series of tests to evaluate the performance of the gyro under conditions similar to those encountered during routine science observations, including moving to targets, locking on to a target, and performing precision pointing.

After these engineering tests have been completed, Hubble is expected to soon return to normal science operations.

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74 thoughts on “NASA fixes the Hubble Space Telescope

  1. Good to see that there are some folks with NASA who know their business and don’t waste their time fiddling data.

  2. Just deorbit the thing. It was a great tool that has done much to advance science, but all good things must come to an end. It will continue to fail and it should be deorbited it they still have control and the ability to do so.

    • What a silly comment. Soon Richard Branson will be popping up there for a weekend break. He can take up a spare gyro.

    • If this fix works, it can continue doing science.
      Even if the gyro in question fails again, they will still be able to control it well enough to do a controlled deorbit.

      • While that may be true, it is indicative of an aging platform where more systems can be expected to fail. The telescope is well beyond its design life. We can not go back up to fix it. The next failure could very easily be in a system that would render it unable to perform a deorbit maneuver. Sometimes you have to know when it is time to throw away old equipment.

        • “Sometimes you have to know when it is time to throw away old equipment” I dunno, 7-1/2 years without a restart isn’t so shabby. “well beyond its design life” != worthless.

        • In that case, better deorbit everything as soon as it achieves orbit. After all, something might break tomorrow.

          • No but after almost 30 years on orbit, it is fair to assess whether it is worth spending more money on. We spend over $80m per year on program costs. That ratchets up to almost $100m by 2020. Bring it down and clear the orbit and budget for new and more advanced missions.

    • With all due respect, unless you are an engineer with specific knowledge of the hardware used by the Hubble Space Telescope, and have extensive experience with the aging of space-based platforms, I’ll trust the evaluation of the engineers at NASA over your opinion.

      • Basically its a value judgement. Can the new information we get about space stuff be obtained any other way with any other program in orbit or planned? Are we better off with or without that information? If the Hubble is no longer in orbit there will be NO new information from it. Is that better or worse?

  3. Seems similar to the Epley maneuver used to treat benign positional vertigo in humans. This corrects the vertigo by getting a small otolith to fall into a pouch in the semi-circular canal. Several coordinated positioning moves are strung together to achieve this goal.

    • Caught a local youth trying to rip the clocks off my Guzzi a couple of years back. A swift Epley maneuver cured his vertigo too.

    • A couple of months ago, I had severe vertigo when I arose from a lying-down position or turned over on my right side. My primary care manager referred me to a physical therapist. She had me go through different motions (mainly falling backwards on a exam table with my head sideways at as 45 degree angle and off the side of the exam table). When I left the facility, I was so dizzy, that I felt like a drunken sailor (I thought, “what have I gotten myself into”.) That night, I woke up, and my vertigo was completely gone. And it hasn’t returned since. I took good notes, so if it returns, I’ll know what to do.

  4. Newer generations of gyros don’t rotate, they vibrate. Apparently they are more stable and reliable than the rotating type. The technology has been around for a long time; this article was published in 1993:

    https://link.springer.com/chapter/10.1007%2F978-1-4684-0444-9_11

    It looks as though industry has been slow to take up vibrating gyros, although there was a rumour that they were used in the cruise missiles of the first Gulf war, the ones that went through windows. The rumour said that US military wasn’t letting the technology out.

    I only learned this because we now (in the last 2 years) have gyro surveying instruments that can measure the track of the skinny drill holes used in mineral exploration. I did some back-of-envelope calculations that a gyro less than an inch in diameter would have to spin at well over a million RPM, and this seemed implausible. That’s when I heard that they vibrate now.

    These are north-seeking gyros; we had older versions that only measured the change from the initial azimuth, and they precessed, as gyros will, so you had to survey the hole with the gyro going down, then coming up, and hope that the rate of precession was constant. They were still an improvement over the magnetic compass types that were affected by magnetic anomalies.

    I love the way people keep coming up with new and better technologies. And, AFAIK it wasn’t the Obama administration letting military technology out; it was a bunch of Aussies and Brits who did it from scratch. The theory is old, anyway, it was the engineering that was innovative (in case anyone wanted to make the same point we’ve heard a few times before).

      • As I understand it, it would not be physically possible to establish initial ‘firm’ link between surface and the geostationary orbit since any rocket pulling initial ‘tether’ would be required to have a ‘near geo-synchronous’ flight for whole of 40,000 km, not forgetting possibility of what I would call a ‘ Rossby wave whiplash’ on the structure of a proposed elevator.

          • It’s theoretically possible, but the engineering at the moment is not possible. Someday though, we may ride elevators to and from orbit.

        • Space elevators look like a great idea – at least to those promoting them. Just kike AGW, the PowerPoint presentations are compelling. I’m sure there are many others on this forum who would like to understand whether the physics really works or not. Do you have a few links to get us started?

          • Oh, there’s no problem with the physics. It’s really quite simple. Kind of like putting an object on a string and whirling it around a central point. But in the case of a space elevator the string would be a ribbon made of something very strong, likely carbon (think of long strings of carbon nanotubes). The weight would be some mass out at 2x the geosync orbit and at geosync a station for docking spacecraft, etc. The only real problem is that the engineering is currently beyond us. But that will eventually change.

        • vukcevic,
          More likely, an initial cable would be fabricated in orbit and then “flown” down to the anchor point. When it hooked up, there would be some titanic forces involved, but then that’s part of the engineering we’ve yet to solve. Doesn’t seem impossible though.

          • It is currently impossible with all known or proposed materials. Nothing we’ve got (or are experimenting with, including CNT (Carbon NanoTubes)) has sufficiently high tensile strength and sufficiently low density such that the tether doesn’t snap under its own weight.

            Even our most advanced materials (CNTs) are only about 60% strong enough, and we still haven’t figured out how to make them longer than 500 centimeters, nor how to braid them together without breaking them or having them reorient their covalent bonds between strands (which would weaken the tether).

            A further problem is that the areal density of the CNTs decreases as they grow longer, so they have to come up with better catalysts before they can grow CNTs longer.

            A further problem is that CNTs have only 3 bonds, leaving a 4th covalent bond available, making it electronegative… and once that tether’s in the air, we have no guarantee what molecules will covalently bond with the CNT and what sort of functionalization will result.

            For instance, CNTs in an argon plasma (as would be found high in the atmosphere) will functionalize with oxygen and fluorine (as would be found high in the atmosphere), drastically decreasing the tensile strength of the CNT.

            So unless they find a way to build a continuous CNT tether 100,000 km long, figure out a way to boost its tensile strength by at least 1/3rd, and somehow seal it so it never interacts with the atmosphere (with some sealant that never interacts with the CNT nor the atmosphere), we’ll never have a space elevator.

          • “Everything is theoretically impossible until somebody does it.” I don’t remember who said that originally, but I know it’s a science fiction author. If you think about it, pretty much everything we have today was impossible at some point because we lacked understanding about some (or many) thing(s). I think that space elevators have so many advantages to other methods of getting into orbit, that we will eventually solve all the technical challenges and build them. They may not be built with CNTs, but they will be built.

  5. I wonder if the fluid was congealed in the gyro, and when started up formed a warm area around the wheel for a while which created a low resistance zone and resulted in overspeeding, until exercised enough to mix less viscous heated liquid into colder gel surrounding it.

    • Ed, that’s why they need a space-tug that docks at the ISS to permit excursions for repair or retrieval/relaunch of satellites. It should also serve as a “lifeboat” for emergency evacuation. To me it’s not acceptable to be up there without both those capabilities, preferably in the same vehicle.

    • The first step was completely redesigning Hubble’s camera to cope with the malformed mirror, and working out how to correct the images in software. Until that was done, there was no mission, and the project was a write-off. A friend of mine I was at college with did that work.

  6. Keep in mind Hubble was not in low Earth orbit where the shuttle operated. The repair was a special mission to get up high enough to reach it, and actually more dangerous than normal. As far as de-orbiting Hubble, it will remain in orbit if it dies for quite some time due to how high it is unless it is intentionally directed down.

  7. I’m impressed that the gyro restarted at all, after being turned off for 7.5 years. And then they got it to work properly. There’s some serious good engineering in there, and it’s all just slightly short of miraculous.

  8. Hubble takes a lickin’ and keeps on tickin’!

    Love that Hubble! Such good pictures! Some of the best money NASA ever spent.

  9. “This procedure turned the gyro off for one second, and then restarted it before the wheel spun down”

    Bloody hell – Windows operating system???

    “Sir, can you turn your computer off then turn it back on again, that will clear the problem”

    ROLF!!!

  10. I think Hubble should be completely used up, right to the day that it can no longer follow a controlled de-orbit.

    Then as Hubble tumbled in a final uncontrolled spin and gathered velocity, all the little critters on the surface began to make excited squeaking noises and emitted a series of spinning newspaper headlines of DOOM like those seen in a campy old newsreel. Academia nuts cheerfully discussed infinitesimally low probably impact events in stern voices, and their interviewers nodded gravely, as if humanity covered the Earth completely to a depth of 20 meters and this bus-sized object presented the greatest danger they had ever faced. It was amusing.

    As fate would have it however, despite the vanishingly low probability a single solid piece did manage to trace a brilliant burning path toward an elderly woman standing in her back yard witnessing the announced descent. It wholly obliterated her and carved a smouldering crater.

    After they had gathered a few bits of her and buried them the family called a press conference in the back yard. It was a news event carried live to the world, and the woman’s tearful son stood for a moment in silence but for the incessant whirring and clicking sound of cameras, which was dubbed in because cameras had not whirred or clicked for years.

    The press were gathered to witness the onslaught of the backlash that was sure to follow. Hubble had fallen in the same country that had created it, now widely known as the most litigious society on Earth. Any moment now her son would rally a wounded primal cry of hatred, step aside and his lawyers would mop up in measured tones and describe their sweeping campaign that would leave no Hubble contractor or NASA or the Federal Government unscathed. Once there had once been chance lotteries whose winners had been celebrated. Now life itself was the lottery and the process was so streamlined even petty grievances were like playing the slots. This would be a massive victim payoff and everyone would follow it with tabloid relish. And it was about to begin.

    “Momma loved to look at the stars,” her son began with a sob. “But her eyesight was never very good.” The press all blinked in unison. Something was not right. Where was the outrage?

    “When Hubble went up and those photographs started coming in, she rejoiced. She couldn’t get enough of them. She’d say ‘Look here! This is God’s creation! It’s so much bigger than the church ever knew!’ and things like that. When Hubble’s mirror was repaired she sent NASA a handwritten letter thanking them all personally, and in it she said, ‘It’s okay, everyone makes mistakes. Everyone needs new glasses sometimes. You made it right.’ and I’m sure someone there has it on their wall…”

    “In 2018 there were some problems with gyroscopes and Momma read up all she could about them, what they looked like inside and what was the problem. This was puzzling to me and I asked her why. ‘Well it should be obvious! I may be the one and only person who will pray to God for gyroscopes to heal. I have to be specific.’ Which amused us at the time, but when they started working again I wondered if their desperate maneuvers had been helped along with a little nudge? Momma would not have it. ‘No silly boy, God did not lay a finger on them but my prayer was answered. How much do you know about gyroscopes?’ she asked, beaming in her newly acquired knowledge. ‘All He did was grab hold of the Universe hold it gently still while NASA did the work. Without his hand on the firmament there would be nothing to push against. Nothing could be done. He works His finest miracles through others,’ she concluded solemnly.”

    “So as I stand here today to honor my mother, I am recalling times over the years when certain voices called for the retiring of various spacecraft, including Hubble, for reasons of budget or end of usefullness. Mamma scoffed at this and wrote more letters, some of them vicious. ‘Why should spacecraft not fight to survive just like ideas and people, and just like people, struggle to postpone death until the last? Since when has the moment of one’s death been up to some committee? Not on my watch! Even if they are things, we must cherish the things that have brought us joy, until the very end. It is our covenant.’ When the Mars Opportunity Rover died, Momma prayed for it to find salvation in its own way. But she also wrote a scathing letter to NASA accusing them of parental neglect for not giving it a nuclear power source. The Voyager spacecraft were a great source of inspiration to her, even as its batteries were waning. ‘They have already had a full blessed life’ she would say. ‘Anything at this point is icing on the cake.’ And my friends, for Hubble there has been a great many years of ‘icing’. While there have been many finer and sharper telescopes put into orbit, Momma considered herself Hubble’s devoted fan. ‘Those other fancy telescopes have been taken over by scientists,’ she said. ‘And Hubble, because it is still working but not as powerful, has been taken over by philosophers like me. It has become a tool of inspiration.’ ”

    “And… as to the way she died…” the ridiculous camera noise started whirring and clicking again. “She was fond of jokes. She would have a good laugh about it. That is all. Thank you.”

    And so it was that the greatest lawsuit the world had ever seen, never happened. Hubble had fallen and the year was 2038.

  11. If in doubt give it a clout if at first you don’t succeed get a bigger hammer.
    Has served me well for many years of fixing things.

    James Bull

  12. Sounds a lot like when I rocked the the washing machine back and forth on a concrete floor to get it working.

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