PC World Business

Behind every robot is a driver. While NASA's twin robot geologists, Spirit and Opportunity, have gained plenty of media attention since they first landed on Mars at the start of 2004, little attention has been given to the team of dedicated IT workers behind the robots, plotting their every move.

We talk to Scott Maxwell, one of 14 Rover Drivers that work in NASA's California-based Jet Propulsion Laboratory, and find out what it is like to control a robot on another planet. Maxwell discusses what makes up an average work day, the highlights of the project, how he got the job, and the tools he uses in his work. Ashley Stroupe also discusses her life as a robot driver in the next part of this two part series.

What in your opinion are the top three discoveries the Rovers have made?

The Rovers went to Mars to help us tell the past story of life in the solar system by looking for evidence of past water activity on the Martian surface. Both Rovers have found such evidence, so I'd choose two of the top three discoveries as independent confirmations of past water activity on Mars -- Spirit on her side of Mars, in the Gusev Crater, and Opportunity on the other side, in the Meridiani Planum.

But maybe their most significant accomplishment has simply been proving that this can be done. Before Spirit and Opportunity, we'd never successfully operated free-roaming Rovers on the surface of another world. It was, in part, an act of faith that we could do it and that it would produce good science. But both Rovers have shown, quite conclusively, that this is not only a terrific approach from a science point of view, but also one that engages the public in a new way.

What does an average work day consist of, from when you arrive in the office to when you leave?

We arrange for our work day here on Earth to match the Martian night, so when the solar-powered Rovers shut down for the Martian night, they send us pictures and other data showing us where they are now and what they did the previous day. Then they go to sleep, and we go to work planning the next Martian day of activities. At the end of our day, we have a list of commands to send the Rovers when the sun comes back up in the Martian sky. At that point, they go to work, and we go to sleep.

The Martian day is about 40 minutes longer than an Earth day, so this affects our work schedules: some days we start earlier, some days later, and sometimes we plan two Martian days at a time for the Rover and skip every other day here on Earth. (We do that when the Martian night starts so late in the Earth day that there isn't enough time to plan a regular day of activities.)

Insofar as there's an average work day driving the Rovers, it looks like this: as fast as possible -- usually within the first half hour -- we assess the results of the previous day, make sure there are no concerns, and work with the science team to make a good guess as to what we should try to achieve that day. Over the next hour or so, we refine that plan, until we have a solid high-level idea of what we're trying to accomplish -- drive over to that nifty-looking rock about 20 metres away, or pick up the Rover's arm and put it down again over there for example.

The rest of the day involves turning that high-level plan into detailed commands that the Rover can execute. First, we spend an hour or two putting together a good enough version of those commands so that we can show the whole team an animation. Then we hold a meeting where all of the engineers and scientists approve the detailed plan and review the animation together.

In the last phase, we spend a few more hours refining our first cut, debating what-if scenarios. What if that patch of soil is deeper than we thought and we swerve off course while driving through it? Or what if we start to go off course and whack the solar panels into that big rock? We make sure that the commands we're sending to the Rover will do the right thing in the face of all imaginable contingencies. We review this final cut at the day's commands -- twice! -- and if we can't find anything wrong with it no matter how hard we try, we send it to the Rover.

The next day, it starts all over.