Overconservative

The entire drive up from Boca Raton to Titusville, I was listening to the radio, wondering why they were still talking about the failed ECO sensor as a potential flight issue, and hoping that they weren't going to scrub on account of it, but if they were, I wished the entire way up, with every mile, that they would do it now, so we could stop wasting time and gas. What I couldn't understand was what the MMT expected to change in the hours leading up to flight that would make them suddenly decide that they were going to follow the (absurd) flight rule.

They knew in the early morning hours that they had a problem. There was no reason to think that it was going to fix itself prior to launch. So if it was a violation of the launch commit criteria to fly with a failed sensor an hour before launch, why wasn't it eight hours before launch? Why did they put the crew in the vehicle, and have them sit on their backs for hours, why did they let everyone drive from all over the place to attend the launch, if they weren't going to fly with it?

The only possible excuse that I could come up with was that they were waiting for the best possible weather report for a next-day launch. If the weather was deteriorating for Saturday, then they might have made a last-minute decision to waive, and flown on Friday. As it turned out, the forecast for Saturday was good (and in fact better than existing conditions on Friday), so they may have decided that, since they'd have one more shot, they might as well do a tank drain, see if the problem cleared up, and do it then.

Nonetheless, it's not the decision I'd have made. A delay of another day lost them a day of contingency at ISS, and it risked something else going wrong in the recycle. They were all ready to go on Friday, other than the failed sensor, and that shouldn't have kept them on the ground, since the new rule was an overreaction to Columbia, anyway, and they should change it back to what it always was--fail operational (i.e, only two sensors are needed, and the other two are available for redundancy). When I was at KSC yesterday, I talked to one of the briefers in private after a status briefing, and said that they were crazy not to launch Friday. He agreed that they've overconstrained the system to make it almost impossible to meet scheduled objectives, and done so in a manner that makes little contribution to true safety--settling for appearances instead.