3 ms·

Lest you think this sort of thing is something that could only happen to the Ruskies, consider that the same sort of mistake has happened on NASA space probes,

Lest you think this sort of thing is something that could only happen to the Ruskies, consider that the same sort of mistake has happened on NASA space probes, twice. The Galileo Jupiter atmospheric probe deployed its parachutes late because the accelerometer designed to trigger the pyro charges to release the parachutes was wired backwards. There were two different "g-switches" which provided acceleration data at different scales. When the probe entered Jupiter's atmosphere the software control system saw that the acceleration data it was getting was all wrong, it marked one of the channels as failed and attempted to use just the other channel, though the scale was all wrong so the data was bogus (leading the software to think that the probe was in a different stage of its entry than it actually was). The result was that the main parachute was deployed very late and the only reason the parachute successfully deployed at all at the speed and atmospheric density it was released into is by more or less sheer luck. The same mis-wiring happened on the Genesis sample return probe, which caused it to collide with the ground rather than be captured in mid-air as per the plan. The funny part is that the accelerometers on both probes were tested in a centrifuge, but the wiring harnesses for the tests were also wired backwards as well.

grinich 13y ago
The lack of integrated testing was by far the most impressive thing about the Curiosity Rover/MSL landing to me. Most people who followed the news had no idea that the skycrane deployment setup was never actually tested in full. They validated components, like the hydrazine engines, radar, and bridle release mechanism, but not the combination of all. Software and circuits scale through abstraction and the static discipline. But combining atoms just gets harder and harder. (This sort of thing also happens when constructing buildings or bridges, but there's usually not a million different points for potential catastrophic failure.)

grinich 13y ago

The lack of integrated testing was by far the most impressive thing about the Curiosity Rover/MSL landing to me. Most people who followed the news had no idea that the skycrane deployment setup was never actually tested in full. They validated components, like the hydrazine engines, radar, and bridle release mechanism, but not the combination of all. Software and circuits scale through abstraction and the static discipline. But combining atoms just gets harder and harder. (This sort of thing also happens when constructing buildings or bridges, but there's usually not a million different points for potential catastrophic failure.)