October 24, 2004

Scientific and Engineering Failure

Not long ago, the Genesis spacecraft came tumbling back to Earth. It didn't go entirely as planned:

Everything had gone pretty well up to that point, but the dramatic "Catch by the Hollywood Stuntmen" failed, not because they missed, but because the parachutes on the spacecraft failed to open. The impact shattered the somewhat delicate plates that had been sieving the voids of space for the last few years.

The question immediately became, "Was the mission a success or a failure?" That question is followed immediately, at least in my mind, by questions of what would determine success. My first cut analysis would be the following. 1) a clear engineering failure; 2) based on the apparent success at recovering samples from the shattered plates, a likely scientific success.

But that is an overly simple analysis. First of all, with the exception of the last little bit, the spacecraft performed quite well. It spent three years following a wierd path through the solar system. It deployed its sampling mechanisms and collected about 10e20 ions, that is individual atoms, bits of matter, that have been spit out of the sun. Not bad really.

Things went wrong on the engineering front with re-entry. And at the time of this writing it looks as if the problem was that the switches that were meant to deploy the parachutes were installed backwards (this interpretation from The Economist, a more official report blames "a design error that involves the orientation of gravity-switch devices"). (Nature also reported on the switch problem...).

Success of the science mission depends upon the ability of scientists to extract new understanding of our solar system from the samples that the spacecraft collected. The Hollywood Stuntmen that were supposed to catch the spacecraft by the parachute were employed because there was great concern that the thing not crash into the ground because of the fragility of the sampling plates. So things didn't look good for scientific success at first. It now appears that samples will be able to be recovered, identified and useful.

So now I would summarize as follows: 1) with the exception of the parachute bit, which clearly was a cock-up, the engineering was pretty good; 2) the science also looks like it is going to tell us something along the lines of what was proposed years ago.

But both of those are hedges, to the Real Question, which is - Was the Genesis Mission a success? And despite the basically happy endings, I would argue that in important ways (beyond the parachutes), the mission failed. It seems to me that "parachutes fail to open" is an obvious late stage scenario. And the importance of considering this option is highlighted by the initial despair on the part of the scientific team. How is it that such an obvious possibility with such a disasterous implication relied on the correct installation of nearly symmetric switch the size of a pencil eraser with no backup?

My guess is that the scientists and the engineers weren't talking to each other as much as they should have been. And that is the real failure of the mission. Despite the decent recover on the part of the science team.

A bit more on the ALCS series. The "post-season" modifier is indeed irrelevant. Going 4 straight to win a best of 7 series has only happened on two other occaisions in professional sports, both in hockey (now isn't that interesting, are the statistics of hockey streaks different than baseball?).