This is a little bit nerve-wracking, although it's exciting.

This mission will greatly expand our scientific understanding of Mars, pave the way for our next robotic missions later in this decade and help us prepare for sending humans to Mars.

As long as the vehicles remain healthy and they continue the science return, we'll do what we need to do to keep them operating and learning. An asset on the surface like this is invaluable, and we certainly wouldn't want to prematurely cut them off.

Spirit and Opportunity are approaching targets that a year ago seemed well out of reach. Their successes strengthen NASA's commitment to a vision with the ambitious targets of returning samples from Mars and sending human explorers to Mars.

Spirit has climbed to the hilltop and looked over the other side, but NASA did not do this just to say we can do it. The Mars rovers are addressing fundamental questions about Martian history and planetary environments.

It's a little nerve-racking even though it's exciting.

It's going to be difficult to get it into orbit. Mars is hard, Mars can be unpredictable, but we've got a good team here.

First we have to get it into orbit, which is not an easy task.

Mars doesn't treat you very well, for the most part. So this is a very challenging thing to do.