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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comes from the fact that it's been up there for nearly two decades, and therefore carries computer systems long outdated here on Earth.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."
well if the Hubble has at least 640k memory it should be fine. . . .right?
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 sent my Amiga 500 into orbit in 2001 using a homemade trebuchet (granted, quite a large one) and a very high mountain. It broadcasts the Pinball Dreams high score list every two hours on the hour. The problem is, the last time I went up to do some improvements (long story) I had forgotten a few vital 68000 assembler directives, so I was unable to make the transition from antiquated late-80s desktop computer to cutting-edge ASAT weapon. Too bad, now the 10kT warhead I attached to it is probably just sitting there, twiddling its sub-critical materials.
I would imagine it's a little more difficult than simply popping out the CPU and putting in a new one. If you were tasked with upgrading a 486 here on Earth, how many components do you think you'd be able to recycle into the new machine? You'd end up replacing the whole thing, maybe keeping the HDD around just long enough to get your data off it.
"I'm not sure I like the fugnutish tone you used in your post!" -RogL (608926)-
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
A quote from the famous "Real programmers don't use Pascal" article written in 1983. Some of the most awesome Real Programmers of all work at the Jet Propulsion Laboratory in California. Many of them know the entire operating system of the Pioneer and Voyager spacecraft by heart. With a combination of large ground-based Fortran programs and small spacecraft-based assembly language programs, they are able to do incredible feats of navigation and improvisation-- hitting ten-kilometer wide windows at Saturn after six years in space, repairing or bypassing damaged sensor platforms, radios, and batteries. Allegedly, one Real Programmer managed to tuck a pattern matching program into a few hundred bytes of unused memory in a Voyager spacecraft that searched for, located, and photographed a new moon of Jupiter. The current plan for the Galileo spacecraft is to use a gravity assist trajectory past Mars on the way to Jupiter. This trajectory passes within 80 +/- 3 kilometers of the surface of Mars. Nobody is going to trust a Pascal program (or Pascal programmer) for navigation to these tolerances. If you have never read it, it's still a great read (at least for us old-timers). http://www.pbm.com/~lindahl/real.programmers.html
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.
This is a bullshit article. Unfortunately, that has become the norm for Popular Mechanics.
The Intel 486 is hardly some arcane CPU that's so old that nobody knows how to program it. Anybody who can write assembly for modern PCs can write assembly for the 486. And anybody who wants to write in a higher-level language can -- because all the 486 development tools are still easily available.
If you read the article, you'll find that it presents no evidence whatsoever for its assertion that the Hubble's use of a 486 makes it harder to repair. In fact, it reads more like, "The Hubble has a 486, and damn that seems outdated to me! Maybe that's why it's so hard to fix!" Really, that's about the level of the 'logical' argument that you'll find in the article.
Can't they just remodulate the shield harmonics or reverse the polarity of the neutron flow or something?
echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;