It's such a complex spacecraft. This is probably one of the most complicated spacecraft ever manufactured, and we're building not only one, but two. We have a barebones staff here which is very qualified, but we're stretched between two different spacecraft. And we did discover these problems before launch, and we discovered them in time to get them fixed. And that is actually a very exhilarating thing, to see how the team reacts when a problem does occur.

Now the spacecraft was about to "leave home", we asked Art what personalities have developed. Had the two rovers grown different characters?

Art Thompson: "Absolutely. Basically, the two spacecraft react at different levels, different stages, so we have to adjust parameters to make sure that we understand which spacecraft we're working with. Different draws of electrical current, which tells us the health or the state of the vehicle. We're constantly updating our understanding of either vehicle, and one of the things that our test team has done is we've intentionally not segregated them. They work one day on MER-1, the next day they'll come over and work on MER-2. And sometimes that can be a little confusing, but it's really good to see how the team comes over and realizes within the first five or ten minutes which spacecraft they're working on, just from looking at the telemetry.