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."

Comments

Re:Why not simulate it?

[io333]

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?

Re:7400s hard to find?

[mikewas]

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!

Re:port the software? ... try hardware!

[rodgerd]

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.

Re:It has 64k of memory

[henley]

You don't mean the kind that looks like jillions of tiny tires (or black donuts) intersecting with the wires of a chain-link fence, are you?

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...