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Houston, We Have a Software Problem
An anonymous reader writes "The computer system that launches the Space Shuttle is an old, but important, computer system. It is built from mid 70's technology and features SSI chips like 7400's...which are getting hard to find. It has 64k of memory and no room to repair any software bugs. NASA started the CLCS project in 1996 which uses state of the art computer languages, OO methodologies, and hardware. Everything that you could actually hire people off the street for. However, NASA is in a budget crunch with the Space Station cost overruns. It is looking to trim costs to keep the Space Station going. There are stories about CLCS getting cancelled here and these guys say its already cancelled."
There comes a time in every products lifetime when its time to start over,.
Exactly. And that includes the shuttle. It has never lived up to what it was envisioned to be and it is only going to become more costly and more failure prone in the future as every bit of hardware on that pig is already showing signs of fatigue.
There are many launch systems that cost far less per pound to throw things into orbit. The reasons we still have those monstrosities flying are political only, not technological or scientific.
Sure this is flamebate. (Gosh, getting rid of the old karma system is so LIBERATING!) But if we can discuss how some little bits of hardware in the shuttle are past their time, why can't we discuss the big bit?
The 54 series parts were like the 74 series, but in a hermitically sealed case, 100% tested over a wider temperature range, and burned in to remove infant failures. For this application they used space qualified components. The same as 54 series parts, more stringent tests, and now the chips are also evaluated for radiation resistance. Any change in the design or production process and the 54 & space qualified chips must be requalified. What can happen is that a chip is produced to be fuctionally the same, but using smaller geometries, and now is more suseptiple to ESD and radiation.
CMOS chips, because of their high impedances, are notorious for ESD and rad sensitivity so they won't do.
With the reduction in military, aerospace, and space spending many manufacturers have dropped the 54 series and space qualified components. They haven't made any attempts to add replacements in their product lines.
When a part is dropped, the manufacturer usually informs the industry of their intent. You're given a date & price for a final order. the theory is that you can buy a lifetime supply of these parts. Industry isn't likely to but any more than they need to complete existing contracts plus a few spares, there's no guarenty that you'll get any more contracts to build items requiring these parts so these purchases will cut into your profits. Government procurment may buy additional components, but lack funding to really buy large quantities.
An opportunity is presented, and they will be taken advantage of. A distributer might buy some additional parts -- since the distribributer has several customers buying a particular part from him, his risk of being stuck with an unseable component is small.
After the final production run, the chip manufactorers will sell the documentation, tooling, and rights to make a chip. There are small manufacturers who buy these, all well as the out of date machinery to produce these parts. They can then make small production runs, sometimes under a hundred components, for a price. In addition, they might buy untested dice or wafers from the last production run. The untested & unpackaged componets are very cheap, so it's more affordable & less risky to buy and store these than the completed components.
So it is possible to still get the parts needed? -- at a price!
"Glory is fleeting, but obscurity is forever." --Napoleon Bonaparte
I was thinking this. Why don't they open some of the current code and some of the requirements they need to "the community".
Think of who space enthusiasts are and what a lot of them do; software and hardware development. In a budget crunch a good strategy would be to allow interested hobbyists to write some of the code, and then have NASA's boys peer review it.
-- The unsig...
Actually, the old AP101 computers may have had 64k of memory (I don't recall). We upgraded those bad boys a long time ago to AP101S which have a whopping 256k. Who could ask for anything more.
FYI: That extra bump in memory allowed us to store the entire Entry program in upper memory so that in the event of a Trans-Atlantic abort, we wouldn't have to wait 20 seconds for it to load from the mass memory.
- "Sweet merciful crap!" Homer J. Simpson
I believe the discussion is about a computer that is based on the ground.. even if not, I think you fail to realize that NASA has been using Linux in space for a while.. PC104 boards with flash (solid state) memory running Linux.
Might I suggest using FPGAs to emulate the hardware old system so the software doesn't have to be thrown out?
Assuming that circuit layouts are available for these old chips, it would be a piece of cake to emulate them in VHDL (a hardware description language) because they are comparatively simple to today's integrated circuits. Once the chip descriptions are written in VHDL, it would be relatively easy to 'port' the hardware over to a new FPGA if the old one dies or whatever. Then it would not be necessary to truly port or re-code any of the currently working code, and it would be much easier to fix bugs and extend it because you don't have the memory and speed limitations of the old system.
NASA falls under the classification of "independent agency" within the Federal government. The budget is hooked up with other agencies such as the Vetran's Administration if that tell you anything about how things are considered.
"player 4 hit player 1 with 0 stroms"
The ISS is a relic of the first generation of US space plans, going back to the 1952 Collier's articles. The assumption was that to further explore the solar system you'd need (a) a reusable shuttle to go to and from orbit (b) a space station as a research facility and also as a base for assembling and testing space-only ships (c) said space-only ships that would leave and return to the space station with crew being transferred by the shuttle to and from earth, ie the station would be a sort of orbital railway terminus or airport.
This was sensible plan if you were looking at a large number of flights per year and/or setting up say regular interplanetary shuttles. *However* it is totally inapplicable to the current situation where *we haven't even been back to the moon in thirty years let alone get to Mars let alone make out-of-LEO human travel routine*.
There is no way in the world that the money will be made available to allow a manned-space flight schedule that would effectively use these facilities; it would make Apollo's budget look like that of the proverbial chook raffle.
What *should* have been done after the fall of communism was a joint US/Russian Mars program. The Russians had the heavy lift vehicle (Energia), the experience with long-duration space living and well-advanced Mars plans. The US had the experience from Apollo in control systems, rendezvous and building landers and the money. An enhanced Energia (or two) launching a Russio-US crew in a US-designed spaceship and Mars lander would have been a far more effective use of the money and skills on both sides, and would really have reignited world interest in manned space flight. If Mars was still inappropriate, they should have looked at a big, long duration moon mission with a plan to set up a base there. For a one-off effort (initially) there would be no point in having the ISS. And if you really wanted a test space station you'd launch it in one go Skylab-style from Energia.
Frankly given the duration of the Russian space-station missions I don't see what else we can learn of relevance to surviving a Mars mission. It certainly doesn't give us experience in the *big* potential show-stopper - protecting against radiation exposure during the trip and solar flares once you get outside the Van Allen belts.
[Finished Stephen Baxter's fabulous novel "Voyage" over the weekend. Alternative history of NASA going to Mars in 1985 instead of building the Shuttle. Read it and weep...]
Replacing it can be harder. I used to work in newspaper publishing; the core editorial systems of one employer were old ATEX J11 systems with a proprietary, tightly integrated OS and application suite. Over time, various aspects of the system were offloaded to more modern systems (eg, PostScript output and integration with graphics from desktop systems had dedicated AIX systems, imagesetters driven by PostScript RIPs, dumb terminals run from dedicated I/O boards replaced with terminal emulators on the desktop).
Despite all this tweaking, the crufty old systems stayed in place. Why? Well, on each of these old boxes, we could support 25-30 journos and the systems just worked, grinding out newspapers day after day.
People kept talking about replacing them, not least because we had to train up operators and engineers on them every time new staff came in, parts were hard to come by (the standards-not-compatible SCSI and ethernet interfaces were picky about what they talked to, and the filesystem could only address 600 MB of disk per system), and they used huge amounts of power and floor space.
For the three years I worked there and in the three years hence no-one has been able to deliver an editorial system that just works. When vendors rolled their rigged demos in, they crash. The major vendors like CyberGraphics and ATEX couldn't point to successful implementations of their new systems producing a decent number of newspapers on the basis of more than one edition per day.
Would it have been nice to have a Unix or Windows based system? Sure. Reduced overheads and training burdens, able to buy the latest and greatest hardware, and so on. But no-one could actually deliver something that worked better than the crufty old J11 systems.
NASA are probably in a similar bind; it's a very familiar problem: old systems developed by tight, focused, skilled teams and developed over the years are very, very hard to replace.
I think it's important to realize that the Shuttle also represents the pinnacle of 1970's computing and that the whole of computing has changed significantly in the last ~25 years. In the 1970's, you didn't worry about things like GUIs (and all the "bloat" that they entail), TCP/IP stacks, extensive amounts of code to deal with the wide variety of hardware configuration, etc.
It's not so much an issue of bloated code as it is an attempt to cover all the bases. The shuttle software was designed with one purpose in mind -- get that shit-heap into orbit. You can't compare it to a modern Linux distro without invoking an apples-to-oranges counter-argument.
Furthermore, the launch of the shuttle isn't handled by a single onboard computer. It's handled by several. Please reference The Space Shuttle Operator's Manual for more on the systems aboard the shuttle. It's a general, non-technical overview, but a great reference, nonetheless.
You ask "where will it stop?" Here's a hint: it won't. And this same argument probably came up in the 1970's when they started writing the spec for the shuttle. The computer aboard the shuttle is more capable than Apollo for a mission profile that isn't significantly more difficult in any regard (generally speaking). Hell, the PDA you have sitting on your desktop right now has far more computing power than all the computers involved in the Apollo program put together, and it certainly doesn't do anything like putting men on the moon.
But again, it's all a matter of the scope of usage.
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Yes, he does mean Core Memory, and yes, the AP-101 as flown in the Shuttle from mid-70s through to mid-90s did indeed use Core memory.
Indeed, the upgrade to the AP-101s with (I think) static-column RAM took so long because Core memory has the lovely property of retaining information even when the power dies - a key factor, sadly, in the ability to retrieve information from Challenger's onboard computers after the 1986 crash. Another key factor is that Core memory is remarkably resilient to bit-flipping caused by cosmic rays and other radiation (events known as "SEUs" or "Single Event Upsets").
All of which meant that it was a major project just to replace that memory with more modern RAM. And it's not just a couple' sticks of SDRAM either - most of the space-savings you'd expect from replacing bulky core with nice compact RAM chips is taken up with additional hardware to a) provide sufficient power support to retain memory in the event of main power failure b) continually scan through memory doing parity checks to detect and correct for SEUs...
Don't diss Core, man...
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I'd rather have a bottle in front of me than a frontal lobotomy