Mars Dead or Alive

Mars Scientist Steve Squyres discusses the possibilities and perils of the current mission to Mars
Edited by Mary Eileen O'Connor

No one can speak more knowledgeably or eloquently about NASA's Mars Exploration Rover (MER) mission than Steve Squyres. And that's only partly because Squyres, a professor of astronomy at Cornell University and former chairman of NASA's Space Science Advisory Committee, dreamed up the mission and serves as the principal investigator of its science payload.

It has a lot to do with Squyres's unfettered passion for the pair of $400 million MERs that, if all goes to plan, will probe Martian rocks and soil for 90 days beginning this month to see if conditions on the surface were ever right for life. (The mission is examined in NOVA "Mars Dead or Alive," premiering Sunday, January 4 at 6 p.m. on TV12.)

In this interview, conducted at the Jet Propulsion Laboratory in January 2003, Squyres talks about everything from why the MERs don't have life-detection instruments to why your laptop at home is "way smarter" than the rovers' computers.

NOVA: In a nutshell, what is this mission all about?
Squyres: With this mission, we're asking: "Where are the places on Mars where life might have been? Where was it habitable?" We're going to do our very best to pick two places that have the maximum probability, we're going to land there, and we're going to do geology. We're going to understand as best we can what the environment was.

NOVA: The selection of MER was the end of a long roller-coaster ride for you. What is this thing that got selected? And what does it mean to you to finally see it happen?
Squyres: Well, what got selected was a big, capable robot field geologist. It's a rover that weighs 350 pounds, and it can travel dozens of yards a day across the Martian surface. It has a whole tool kit of scientific experiments that gives it the kind of capability you'd want a human field geologist to have on Mars. It provides us with the capability to do exploration that has never been done before on the surface of another planet.

NOVA: It's incredible how all this effort hinges on the last five minutes of its flight to Mars.
Squyres: Yes, during entry, descent, and landing, the rover is on its own. There is no back and forth between the vehicle and Earth. We've taught it what to do, and it does it or it doesn't. There's no intervention possible. There isn't enough time. From the time we hit the top of the atmosphere to when we're stationary on the surface is only a matter of minutes. Mars is too far away to interact with it at that kind of distance, so the thing has to be able to do it by itself.

NOVA: When these rovers wake up on Mars, what kind of a world will they be in?
Squyres: It's hard to say exactly, because we've only been to three places on the Martian surface, and the places we're going with MER are probably very different from those. I expect us to get some real surprises, especially with some of the landing sites we've been talking about.

We do know that the rovers are going to be in a very hostile environment for a piece of hardware. They'll be in a place where there's dust to get in the joints, and the temperature varies by 100*C between nighttime and daytime, so solder joints and things like that get expanded and contracted. In a sense, though, they'll be in their native environment. This is the world they were designed for, so I think they're going to do okay.

NOVA: At what point does this become a successful mission for you? When do you breathe your sigh of relief?
Squyres: That's a good question. You can answer it on different levels. The point at which I will feel it has been a truly successful mission is the point at which I feel that we have taken full advantage of the capabilities that these vehicles offer to answer the questions that we've gone to answer -- the point at which there isn't that much more that we can learn with these machines. That's the point at which I really think we can say, yeah, it's been a successful mission.

But I will feel like celebrating the first day we've got six wheels in the dirt. It has been such a struggle from the start of this idea back in 1995, to the point where we're now just about ready to ship them to the launchpad. To have taken it from the original concept to the point where we've got a rover or two rovers on Mars in their native environment driving around and doing science, I'm going to feel a certain measure of success just for getting that far.

-- Interview conducted by Mark Davis, producer of NOVA "Mars Dead or Alive," which premieres Sunday, January 4 at 6 p.m. on TV12, and edited by Peter Tyson, editor in chief of NOVA online. A longer interview with Steve Squyres is available at www.pbs.org/nova/mars.