Crossing Their Fingers

It looks like NASA's not going to abandon the ISS. That seems sensible to me.

I'd like to know where they get the 1/124 number for probability of having to evacuate. But it makes sense, given that they're already down at least one (and actually, more like two or three) level in the fault tree, that you can accept a lower reliability for the lifeboat. Lifeboats, after all, have traditionally been pretty iffy propositions. It's not reasonable to demand high reliability of them. That was one of the complaints that I used to have when working on CERV--that the requirements were overspecified for something that was only for use in an emergency.