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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comes from the fact that it's been up there for nearly two decades, and therefore carries computer systems long outdated here on Earth.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.
They need to have the chips hardened for radiation. I'm not sure what the process entails
I would hope it involves putting the everything in a radiation shielded box. I could see how smaller chip architectures might be more susceptible to radiation, but a decade is enough time to figure that out and use exterior shielding instead of hardening. Sure that might be much more difficult, but if you can't handle difficult don't work at NASA. Of course with a Hubble sized budget, there is no excuse for not having several back-up sets of the non-custom parts that might not be available in a few years. Computer components had exhibited that high turn over rate for plenty of time before Hubble launched.
We are all just people.
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
It's already running on an upgrade. The 486 was installed in 1999 as part of STS-103.
http://en.wikipedia.org/wiki/Hubble_Space_Telescope#Servicing_Mission_3A
IIRC, the 486 was chosen specifically for the physical size of the data paths? Or the dies that cast the chips themselves? Either way, they were large enough that passing radation would be less likely to corrupt data that it would on the newer, smaller pentium based chips.
There are some people that if they don't know, you can't tell 'em.
The US government had a standing order to chip brokers for all the 8087 math coprocessors that could be had. They are used in some military radar units and there is no replacement available.
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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
I had the opportunity to work on a radiation hardened computer for a satellite. This was in the late 90's, and was probably much like the Hubble Telescope processor. We went through endless simulations and scenarios to try and second guess every conceivable error or fault possible. Bit flips were easily handled, but double bit failures were not. When we had double bit flips we had to reload all the software and data anew.
The equipment we used to design and support the onboard system was modern (for that time), but the chips for the simulators were on breadboards that were hand wired for much of it. It was ugly, but there were no available alternatives at the time that were rad-hardened.
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.
He who lights his taper at mine, receives light without darkening me.
They need to have the chips hardened for radiation. I'm not sure what the process entails
I think we went over this not to long ago with one of the Mars craft, or we were it was in the thread about the dangers of outsourcing DoD hardware? (or was that digg..) Regardless, it's generally just tech a few years older that's proven itself without major flaws... http://en.wikipedia.org/wiki/Radiation_hardening#Radiation-hardening_techniques http://history.nasa.gov/computers/Part1.html And of course if your in the market for such kit... www.honeywell.com/radhard/
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