Slashdot Mirror
Cassini Geyser-Tasting a Bust
Maggie McKee writes "The Cassini spacecraft flew into the icy geysers erupting from Saturn's moon Enceladus on Wednesday in an attempt to figure out what they were made of, but a glitch prevented the probe from actually 'tasting' the plumes. An 'unexplained software hiccup' put the Cosmic Dust Analyzer (CDA) out of commission. Ironically, new software designed to improve the ability of the CDA to count particle hits may be to blame. Mission managers may try to re-attempt the plume fly-through later this year."
Or they got warned off...
Cassini: [message relayed from monolith] "All these worlds are yours except Enceladus. Attempt no landings there...."
This is just one data point in a rather big history. At least they didn't confuse feet-per-second with meters-per-second; at least they didn't cause their CPU to thrash due to a radar being left on and overloading the interrupts. Also, this is the same organization that managed to put two quite-autonomous rovers on Mars and keep them rolling for, what is it now?, 4 years. When one of the rovers did have a software failure, and a really bad mission-killing one, they were able to debug it and update firmware OTA from light-minutes distance, on a machine that was only intermittently alive.
They screw things up, but they seem to do very well at fault-tolerance and recovery, and I think if I were in automated systems, I'd wanna be at NASA over anywhere else, period.
Don't blame me, I voted for Baltar.
These craft - their software, hardware, and the interactions between them - are so complex that there is no way to exhaustively test everything. It's complex enough that you can't even determine what an exhaustive test criteria would be. If we wanted exhaustive testing to ensure that nothing wrong ever happens, we'd never get anything off the ground. Mistakes happen, the unforeseen happens, and when communications take hours to go through, it is just plain hard. You live with it, correct mistakes as they happen, and make the best of it. They'll get a chance to try again. They have already logged tremendous amounts of data that couldn't have been gotten any other way - it's not like the whole $1.5b mission is a bust. This probe, the largest and most complex NASA has ever launched, has been operating continuously, with very few problems and no critical failures, for over a decade now.
NASA, in general, is a lot more stringent with its software than most organizations. If you would like to know more about it, you could start here.