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Hubble Repairs Hindered By Antiquated Computer Systems
Andrew Moseman writes "Part of the trouble NASA is encountering while fixing the Hubble Space Telescope comes from the fact that it's been up there for nearly two decades, and therefore carries computer systems long outdated here on Earth. 'One of the main computers that the Goddard team has been struggling with during the repair attempts runs on an Intel 486 chip, the height of 1989 technology.' Many of NASA's long-running missions rely on antiquated systems — the Voyager probes each have about 32k of memory — but the scientists say they can manage."
Maybe I'm just getting old, but a 486 doesn't seem all that big a deal to me. I mean it's not as if it's a completely different architecture to that in use today.
They need to have the chips hardened for radiation. I'm not sure what the process entails, but they don't seem to do it with chips younger than 10 years or so. /. did a pretty good article on this awhile back I think.
I actually don't think you can realistically shield effectively against some types of high energy particles. Nuclear reactors use 6 ft of concrete to shield against neutrons. There's higher energy particles than neutrons in space. I'm sure that external shielding plays a large role in it, but there's probably more to it. The wikipedia article on radiation hardening is actually very good. http://en.wikipedia.org/w/index.php?title=Radiation_hardening&oldid=235697687
What you want may well be impossible. There are no magical materials right now to do what you want. Cosmic rays in the range TeV can't be stopped with a box that can be affordably launched, much less fit into the satellite. It's easier to use chips that are designed to handle them.
NASA already has a backup computer, on which are two independent circuits to do the same thing. Side "B" that is on the Hubble right now is handling things right now, after side "A" quit working.
NASA is putting the last of their spare parts on the Hubble right now, after which, there are no more short of restarting production, which isn't going to happen affordably. They made a lot of replacement parts which were gradually used as there were servicing missions.
486 was officially the only space-rated hardware for a very long time. The problem is that when you create a smaller transistor, it becomes far more sensitive to ionizing radiation... the older the die, the larger - and thus less likely to be effected by radiation. More "modern" processors require more shielding.
meh
One of the reasons particles like neutrons are hard to stop is that they have no charge and don't react with the electromagnetic fields that bind matter together. You basically need a collision between the neutron and an atomic nucleus to stop it.
A particle that doesn't interact electromagnetically, however, is (if I'm not mistaken) less likely to interfere with electronic equipment. Which is not to say hard-to-stop radiation like neutron radiation does no damage at all, but I'd be curious to know whether it's a concern at all for satellites.
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