Hubble Repairs Hindered By Antiquated Computer Systems 193
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comes from the fact that it's been up there for nearly two decades, and therefore carries computer systems long outdated here on Earth.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."
Re:Upgrade (Score:4, Interesting)
It takes several years to develop a radiation hardened version of circuits, in addition to being very expensive. About the most modern such processor is based on the PowerPC 750, aka Apple's G3.
Also, as far as I understand it, processors using smaller processes are much more difficult to harden, which significantly limits modernization.
amazing what can be done (Score:4, Interesting)
in such a small space by a good programmer. Most systems today are so encumbered by having been built by toolkits built on toolkits built on metalanguages ad nauseum that a simple "hello world" program now can run hundreds of K of memory.
My compliments to the programmers who still know how to get the most out of the little resources they're working with on these scientific probes.
Re:Upgrade (Score:5, Interesting)
Re:Hardly that antiquated (Score:4, Interesting)
Hubble's not gonna be wasting it's precious cpu time on running calculations for scientists on earth; they can do that themselves here on much faster processors, rather than divide up processor time onboard a satellite. Hubble will, however, need processing power for alignment; controlling rocket burns to get it pointing the right way, controlling motors to position mirrors, that kinda stuff, which doesn't need huge amounts of processing power. Just decent, realtime, predictable core + software, without things like fdiv bugs, or huge amounts of heat that pentiums+ give off.
Re:Upgrade (Score:5, Interesting)
Actually, some sorts of shielding make things worse. Moderate amounts of shielding just end up providing targets for the really high energy particles, which releases a big cloud of moderate energy particles on impact. The secondary radiation is both more abundant and more likely to interact with the stuff on the inside, and so causes a bigger problem. For space applications, there are intermediate amounts of shielding that will actually *increase* the total dose. (This is the case for cosmic rays, not solar flares; the latter can be fairly effectively shielded against, but is frequently less of a concern.) If you're not willing to put *large* amounts of mass around the thing to be shielded, it's often impossible to improve things all that much.
Hardening often consists of simple changes that are nonetheless expensive because they involve changes to the whole production line -- things like rating all the transistors for a noticeably higher voltage, to reduce the likelihood of a radiation-induced latchup event. As chip voltages get lower, this gets harder. Other changes include things like using isotopically pure boron in your dopants -- boron comes in two common isotopes, 10B and 11B. 11B is relatively immune to cosmic radiation, but 10B will fision when hit -- releasing secondary ionizing particles that cause a much greater problem than the cosmic ray by itself would. So rad-hard chips end up made with (expensive) depleted boron.
Combine these, and you see why it's difficult to find a decent selection of rad-hard chips, and also why an up-to-date radiation hardened CPU can cost over $100k each -- and also why you nonetheless need them, and can't really substitute anything short of a few tons of shielding.
Re:Upgrade (Score:1, Interesting)
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.
No such thing as a radiation shield. Radiation hardening involves redundancy and some software tricks. 486 chip sets are as far as it goes. Anything that uses smaller transistors has issues, from what I've heard.
Re:Upgrade (Score:3, Interesting)
External shielding is often a bad idea for space hardware. The shielding is heavy (as it must be to stop particles), and itself becomes radio-active over time as it is exposed to wonderful effects like gamma rays. We get this free shielding of miles of atmosphere, here on Earth, and we get even more shielding from solar radiation half of the day. (The technical term for this is 'night-time'). That Earth shielding also gets rid of a lot of the more intense interstellar radiation as well.
You can't replace that with a NASA bright idea. You need to work with the physics and chemistry available to you. And frankly, Hubble was not intended to last this long without regular, Space Shuttle provided maintenance. It's a tribute to the original engineering that it's survived as well as it has.
Re:You know you are getting old... (Score:2, Interesting)
Yes there is
Microsoft wrote a document (collaboarating with Hayes, the inventors of the AT command set) so that devices could identify themselves back in the Win95 days.
http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/pnpcom.rtf [microsoft.com]
Back then I remember buying a serial modem, plugging it in and being impressed that Windows installed Dial Up Networking, the Windows PPP client.
This COM port Plug'n'Play was still around at least until XP, there was a driver called SERENUM.SYS in the stack for serial ports that did the bus enumeration. I don't have any Vista machine with RS232 ports, but a quick Google search makes me think it would be present on a Vista machine that did.
Re:Upgrade (Score:3, Interesting)
Definitely, the point being that you get the most scattering in collisions between objects of near equal mass. The closest mass neutral particle to a neutron is a hydrogen atom (with it's approximately 1 electron associated with one proton), and so the important oil-well petrophysical measurement "neutron density" is actually a measure of the mean number of hydrogen atoms per unit volume in the measured area. In contrast, the so-called "bulk density" petrophysical measurement uses gamma ray photons with an energy that gives each photon a comparable momentum with an electron, so the "bulk density" tool is actually giving you a measure of the number of electrons (and hence protons) per unit volume.
It might sound useless to you, but I have to explain this at least once per quarter year to colleagues trying to perform a "quick look" analysis of a set of wireline logs from an oilwell under evaluation. The teaching of these skills is riddled with such obfuscations.