What Spirit found was probably a hot spring or fumarole, the kind of place where biologists think life might have arisen on Earth. It's not equipped to detect evidence of past life directly, but it found exactly the sort of spot we want to go back to with robots (or people!) that can.

Oh, and the first hints of that silica-rich material were turned up by the trenches we dug as we dragged our broken wheel around. Without that hardware failure, Spirit wouldn't have realised one of its greatest successes!

What was your technical background before joining NASA as a Rover driver?

I completed my Master of Computer Science degree at the University of Illinois at Urbana-Champaign, and I have undergraduate degrees in Computer Science as well as English. The degree in English surprises a lot of people, but it's not so unusual on this team -- other Rover drivers on the team have undergraduate degrees in fields as varied as anthropology, sculpture, and chemical engineering.

I came to Jet Propulsion Laboratory (JPL) straight from grad school in 1994 and worked here for about five years, working a little bit on each of a lot of missions, before I landed a full-time software development role on the mission that became Mars Exploration Rovers (MER). That role was to help write the software we'd use to drive the Rovers, and I parlayed that into the Rover-driving job.

What software and hardware do you use to do your job?

Since this is a one-of-a-kind endeavour, the software is almost all custom-built, as you can imagine. We wrote software for driving the Rovers, a collection of tools known as RSVP -- the Rover Sequencing and Visualization Program. We use a lot of other custom-written software, written in all kinds of computer languages -- Java, Perl, Python, shell scripts, you name it. When we need more, we write it.

It all runs on a collection of high-end Linux boxes -- nice systems, but commodity PC hardware. Since 3-D visualisation is a big part of the job, the Linux boxes sport bonzer NVIDIA graphics cards.

In order to plot the Rover's next moves you must need to "become a robot", in the way an actor needs to become his or her character. Do you find that you think more like a robot in your everyday life from doing this job?

That happened to me very quickly. Just a few weeks into the mission, I was walking across the JPL campus, and I realised I was half-consciously evaluating the rocks I saw as if we were planning to drive near them: "No problem, we can drive over that one; oops, that one's too big, better steer around it".

That evaluation is a large part of what we do in our job, and it was quite funny to realise that it had seeped into my real life.

Would you describe your job as a "dream tech-job"?

Yes. Oh, my, yes. I've often said that I have the best job on two planets, and you can believe it.

Read the interview with Ashley Stroupe here.