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Hubble Space Telescope Goes Into Safe Mode
Generic Specialist writes "There is an article on the BBC web-site reporting that the Hubble Space Telescope has finally shut itself down due to the failure of a fourth gyroscope. For some time it has been running on the minimum three out of its six gyroscopes, and on Saturday the failure of another one sent the telesope into its safe mode. We'll have to wait until after the next servicing mission, due next month, before any more science can be done.
"
The gyroscopes allow the operators to point the Hubble. Which is why a minimum of 3 are required. There is no ability to change the Hubble's orbit. To do that would require dragging it into the cargo bay as they did on the repair mission last time and use the shuttle to boost it into a higher orbit.
As the Hubble sits there only Isaac Newton is controlling its orbit. If a large solar flare occurs, hopefully the earth will be between the hubble and the event, otherwise there's little the operators can do, other than close the doors, possible put the processor into some sort of safe mode, and hope for no bit-flips.
It was always expected to have to do a minimum of 2 servicing visits to the hubble for these type of things. Originally they were intended to upgrade the hardware (changing a tape storage device to solid state, etc..) but they always suspected that things like gyros would need changing out.Everyone here seems to be forgetting that space is a particularly harsh environment. Especially considering that in Low Earth Orbit (LEO) a satellite is going to shadow to sunlight (~ -200 degrees to ~ +200 degrees farenheit) many times a day. These environment changes tax even the best engineered hardware, and these problems shouldn't surprise anyone.
Regardless of cost, I think Hubble was a tremendous investment. Knowlege for the sake of knowlege. I like it.
The more "pure-science" that is done in the world the better (science that can not be perverted into a weapon).
Ignore Alien Orders
After getting in touch with the gyro craftsman ("Hans"), the project decided to try to turn gyro 1 on and off again. This was done about 1:00 local time. This did not seem to do any good. The start up cycle went up to about 500 milli-amps (over 700 ma was expected) and then down to the 350 ma level it had been at after the failure this morning. There was no indication that the gyro moved, it certainly did not get into sync. At this time, there is not a good understanding of what actually failed. The "lube patch" theory is now not seen to be completely consistent with the data. The gyro engineers at GSFC and Allied will be reviewing the data and looking at a wider range of possible failure scenarios over the weekend. No further attempt will be made to turn the gyro on until next week.
There will be a meeting/telecon sometime Monday afternoon to review the data and analyses. Meanwhile, the working expectation is that we will stay in zero gyro mode until SM3A. The instruments will be recovered from safe to hold next week. The current plan is to work through the plans for the recoveries on Monday and carry them out on Tuesday. The recoveries will be done in real-time, but an RTCS will be needed for the FOC recovery. The project will be reviewing the situation to identify any housekeeping activities necessary during the period before SM3A. They are also reviewing the process for closely monitoring performance in the zero gyro mode, since this will be by far the longest time we have been in this mode.
A dog-bone shaped satelite with a pair of manipulator arms about to rip it to shreds? :-)
"Pinky, you've left the lens cap of your mind on again." - P&TB
"I can see my house from here!" - ST:
Gyro-99FX3dW00 caused a general protection fault in MSHBLSAT.dll. It may be possible to continue operating normally. Press enter to return to MS-Space and wait for your telescope to recover, or press ctrl-alt-del to send it spiraling down to earth in a heaping flaming mass.
Bad things often happen to good people,
It is up to them to see that they remain good.
It seems like one thing or another has gone wrong with Hubble since it was first put into orbit. How reliable was the design expected to be compared to how reliable it has been?
;)
It's not that easy.
HST was designed to be modular, and in that sense the lifespan is long; each module can be replaced.
The design takes into consideration that the individual modules would need replacement.
Another thing; compared to the amount of money spent on warefare, the amount used on space exploration is peanust.
Anyhow; it is used a lot and constantly bombarded by particles. Give it a break
Assuming it went into deep safemode, the scope is fine. The aperature door will close and the scope will keep position in space. Safe mode is something Hubble's controllers understand very well...
Check out Eric Chaisson's The Hubble Wars for a good description of just how FUBARed the Hubble really is. Among the interesting points: several of the initial gyros on the scope were engineering test models that already had tens of millions of hours of use. A number failed before the last repair mission: they were only 1 gyro away from safe then.
Chaisson (ex-Space Telescope Science Institute high-muckity-muck) was more than a bit critical of the entire design process. Even beyond the the well-known mirror and solar panel problems, the number of design flaws and construction problems were amazing. For example, while it waited for launch nobody could find the documentation that stated that the secondary mirror had ever been installed. They had to tip the scope and build a $BIGNUM "diving board" so someone could climb into the scope and look.
"Seven Deadly Sins? I thought it was a to-do list!"
Many /.ers were asking for details on Hubble. Well I did some diggig up and came up with this Hubble history:
.. can any one give more details ?
--Co-operative program of NASA and ESA
--Design lifetime = 15 years,with a 3 yr cycle of on-orbit service
--Launched by Discovery(STS-31),1990
--2 service missions so far,1993, and 1997
--1993 service replaced two gyroscope Electronics Control Units (ECUs)and fuse plugs for the gyroscopes
But no details on the latest failure even at stsci.edu
Some Links :
http://www.stsci.edu/hst/
http://amazing-space.st sci.edu/service/service-science.html
Manifest
... "follow me" the wise man said, but he walked behind
From the following comments on NASA's mission site, it sounds like the gyros are just too new and different:
:-)
"Why aren't the gyros working?
The Hubble team believes they understand the cause of the failures, although they cannot be certain until the gyros are returned from space and taken apart. Based on nearly one and a half years of intensive chemical, mechanical and electrical investigations, the team believes that the thin wires are being corroded by the fluid in which they are immersed and ultimately this corrosion causes them to break. The fluid is very thick (about the thickness of 10W-30 motor oil), and in order to force this fluid into its float cavity, pressured air was used. The team believes that eventually, oxygen in the air interacted with the fluid to create a small amount of corrosive material and the wires were partially eaten away. Sometimes the wires were strong enough to carry electricity and some-times they were not and they broke. Pressurized nitrogen is now used instead of pressurized air. Using pressurized nitrogen eliminates the introduction of oxygen into this fluid."
Sounds like a much more forgivable error than confusing pounds with Newtons
--
"You can't get something for nothing." - my grandfather, on the stock market and Reaganomics.
I also worked on Servicing Mission 3B, which is supposed to fix the NICMOS Cryo cooler, and add some additional hardware. NICMOS is an infared camera, good for seeing through dust clouds and whatnot. Who knows when that mission is going up now.
Remember, the Hubble was supposed to be launched in 1986, shortly _after_ the Challenger (RIP) disaster.
Hubble sat around for a few extra years and had plenty of time to age. The whole problem with the optics on Hubble was that sitting on earth too long deformed the mirror.
IIRC, Hubble is about 15 years old. It was one of the first (if not the first) satilites (sp?) designed to be maintained by the shuttle. Hubble has been in planning since before the first shuttle flight, so we're dealing with some 20+ year old technology. I would think they are slowly upgrading the old systems with newer tech as they replace them.
Not sure about the lifespan.
then it comes to be that the soothing light at the end of your tunnel is just a freight train coming your way