P2K: When we spoke before you talked about at some point having to make some real hard tradeoffs between things that would be nice and things that just aren't going to fly... Have you had to make any hard decisions so far that have resulted in things that were initially desirec being taken off the spacecraft?

Pete Theisinger: No, we've been very fortunate in being able to hold the line. We've really... As John Casani at the Laboratory likes to say, "Keep your grip." We've really kept out grip here, and kept our cool. We haven't over-reacted to bad news. And that has turned out to be justified by later events. So... those possibilities still exist. Schedule complications and difficulties could force us to not be able to include in the flight software all the bells and whistles we would like to include. That's a possibility that's there, but not yet needs to be confronted. We are working on airbags and, um...

And as you know, landing on Mars is a difficult thing. The thing I refer to as "the last one meter problem," or "the last ten meter problem". It's the fact that when you hit the ground the environment that you are hitting is not under your control. And so we have to accommodate a set of rock sizes and a set of rock distributions and some slopes and a variety of parameters in the landing environment that we have got to be able to accommodate, and we are going through an airbag test program... The results of that may be that maybe one of the more rocky landing sites, potential landing sites, on the planet, that the scientists have on their short list now, might have to be excluded from safety reasons: that may be another difficult choice, but we're not there yet. We're 6, 6-7 months away from having to confront that issue.