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To MARS with MER - RESEARCH/ers
Mars Exploration Rover Project Manager
NASA Jet Propulsion Laboratory
"Driving to the Review Board, October 2001"
P2K: I was at Plum Brook on the day of some of the first (airbag) tests... and I heard some pretty worried telecons back to base, standard operating procedure at start of tests?
Pete Theisinger: Well I think that, um, that we were a little bit surprised by what happened at Plum Brook in October. We had... there's always a message here, and that is that to keep your optimism under control. One of the engineers that worked for me a long time ago used to use the phrase "constructive paranoia", to refer to the mindset of not expecting it all to go like you thought. And I think at Plum Brook, we had done some tests, earlier that year with inherited Pathfinder airbags that had been around for a while, and those tests had some very modest and minor difficulties, and we attributed those modest and minor difficulties to deterioration of airbags because they had not been kept in a controlled environment during their storage.
And so we came into the October suite expecting that we would be able to land a very heavy mass, with a very high velocity, really outside the bounds of the design, but we wanted to, kind of, put a stake way out there: we could say, OK we can do this, it's like kind of a lead-off double, we've got a slam-dunk here.
And we backed up into a condition more aligned with what we think we really need at the envelope case. And we went through a series of tests which were mostly successful: we discovered some detailed design issues, that we are addressing in the airbags we are making now for the suite in January and February. So, it's, umm.... When your reach gets to be too long, testing can give you some unpleasant surprises. I think we were just a little optimistic and we got caught by that in October.
But, you know, these things all have benefits. You go back and you dust off your thinking, and you look at corrective actions and you decide, "Boy, I really don't understand it as well as I do... I thought I did," and complacency is removed and firmer and more detailed analysis is engaged in. So we are now basically manufacturing different airbag designs, I think we've got about 6, that we're going to drop in the January-February time at Plum Brook, and we expect that there'll be... some of those designs will be successful, and we will then pick and choose from those options to see what we ought to take for the baseline for flight...