With the Hubble Space Telescope about to be reconfigured, there's been some good natured fun poked at the fact its computers are powered by old school 486's. This is not your father's 486! NASA does things a little differently as would you under similar circumstances. Remember, these chips are operating under extreme temperature and radiation conditions and have to undergo the rigors of Earth launch to space and the attendant G-force. This is hardened electronics.
I haven't been able to find the original specs (Hubble launched in 1990 but was designed and tested in the 80s) but I do know today NASA brags, "Hubble components must endure harsh tests at NASA's Goddard Space Flight Center." Harsh doesn't begin to describe them. They have to be as bad as the conditions which will be met in space or the whole exercise is worthless!
In typical NASA fashion they've produced a video on "NASA's Chamber of Horrors," featuring systems engineer Kevin Boyce as the tour guide. There is the obligatory centrifuge to simulate g-force. The centrifuge can exert 30-Gs, a lot more than you or I could take. On most shuttle missions the astronauts "only" hit about 3-Gs on the way up.
As the Space Shuttle gets set to fire its engines, NASA bathes the launch complex and vehicle with water. It's a crude but effective way to dampen vibration--a shock absorber. It's only so effective. There's still plenty of shaking going on. That's why before electronic parts get launched they're strapped to vibration tables equal to any paint shaker at Home Depot. Once the shuttle lifts extreme vibration comes in the form of noise from the massive rockets. Electronic components are blasted with noise in an acoustics chamber to make sure they're up to it.
The CPU's clock can easily become a small radio transmitter. For that reason electronics for space are both listened to and bombarded by RF to make sure they neither interfere nor are interfered with. It's done in the Interference Chamber which allows a controlled environment. In the Space Environment Chamber components get fired up in a vacuum as the temperature is pushed between 300°F and -310°F. Those temperatures represent the difference between full sunlight and shade in space. These tests can take weeks!
In NASA's out-of-this-world world you can't just drive over to Frys for a CPU and some Doritos. You've got to have gear hardened for the occasion and tested scrupulously, which usually means mission electronics well behind what you have on your desk. It's a sad NASA fact of life.
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October 17, 2008 5:54 PM
Ah, it's always refreshing to read people who actually understand the limitations of putting technology into orbit. When you spend so much money just to put a piece of equipment under extreme stress when you launch it into space, you'd better make sure that not only does it survive the trip in working order, but that it's light enough to make the trip affordably.
I can't count how many times I read comments around the Web where someone says "well why didn't they just add -this- or -that" to a satellite, a rover, or probe. Usually it's in response to someone reporting a problem with something that would be a trivial fix if it were earthbound, but is obviously much more complicated when it's in orbit or on the surface of another planet - but the triviality of brushing the dirt off of a scoop in your backyard pales in comparison to what it would take when that probe is, let's say, on Mars.
The thousand-dollar toilet is expensive for a REASON, folks! :D
October 17, 2008 10:39 PM
Thanks Alan -
My head is already swollen enough.
I think one thing NASA never forgets is these probes are tough to bring back to the shop. Hubble's designed-in ability to be upgraded and repaired is the exception, not the rule. With most space hardware, once it dies, it's dead!
Geoff Fox
October 20, 2008 1:21 PM
Good write-up! Stuff like this needs to get out to the public more in order to quell inquiries like "why does it cost so stinking much to send a little box into space?" Also, people don't realise that the space program's budget is but a very tiny portion - less than 1% - of the Federal budget. So yeah, $3billion on the whole for Hubble to date...considering what it's produced and accomplished...to the average American it's pennies a day and THAT, my friends, is one helluva bargain! Think about THAT next time your $1,500 laptop goes on the fritz when you drop it 3' onto a carpted floor!
October 20, 2008 8:57 PM
Ground control to Major Tom.I love this rocket science.Like Michael C.said more of this stuff needs to get to Joe Average.The only problem with that is Joe Average is to worried if his Budweiser is cold or if the old lady restocked the "fridge".We deserve what we get and that ain't gonna be pretty guys.