Top scientist looks back on Martian marathon

Steve Squyres, principal investigator for the Mars rover missions, describes the initial maneuvers of the Spirit rover on its landing platform in this photo from January 2004.Robert Galbraith / Reuters

Steve Squyres always knew he'd be running a marathon on Mars, but he never thought the run would last a year.

Nevertheless, here he is, still working as the principal investigator for the Mars Exploration Rovers.

When NASA's Spirit rover landed in Mars' broad Gusev Crater on Jan. 3, the scientists were planning for a primary mission of only 90 Martian days, or "sols." And when Spirit mysteriously went out of contact two weeks later, just before its twin Opportunity rover was to make its own risky touchdown, it looked as if the mission could come to a premature end right there.

"It was a dark few days," Squyres, a 48-year-old astronomy professor from Cornell University, recalled last week in a telephone interview.

Both rovers not only survived, but thrived: Opportunity still looks as if it "just came off the showroom floor," thanks in part to a clean sweep of its solar cells, Squyres said. And after a rocky beginning, Spirit is doing just fine in Gusev Crater's Columbia Hills, with even brighter skies ahead.

"We are well past the coldest, darkest months of winter on Mars now," Squyres told "The sun is coming back to the south, and each day the solar array output seems to get better and better."

The anniversary of the twin-rover mission is being marked with a splash, including a round of news briefings and the cutting of a "rover birthday cake" at NASA's Jet Propulsion Laboratory. The festivities air on NASA Television, starting at 1 p.m. ET Monday.

More birthday greetings arrive on Tuesday, with the premiere of a public-TV documentary titled "Welcome to Mars." The "Nova" documentary follows Squyres and the rest of the team at JPL as they shepherd the rovers through their mission.

Today, Squyres no longer operates out of JPL in sunny Pasadena, Calif. Instead, he is telecommuting from his home base at Cornell, in frosty Ithaca, N.Y. — and loving it.

"Over the summer, we invested heavily in infrastructure. ... Now I can do exactly the same things that I used to do at JPL all day, but do them all in New York, and that for me is a big, big plus," he said.

From his office at Cornell, Squyres talked about the early problems and the latest successes, as well as the "Nova" documentary and the road ahead. I know you never thought these things would last for a year — or did you?
No, I didn't. In my wildest flights of fancy, if you had sat me down, say, after launch, and fed me truth serum and said, "OK, Squyres, how long do you really think they're going to last?" ... my answer would have been, "If we get on the surface safely, get off the lander OK, I think we're going to go 120 or 150 sols. And if really everything breaks our way, one of them could go to 180."

But twice that? And going four kilometers, and climbing mountains, and going down into an impact crater? No. Never would have believed it.

If you had known that it was going to be a year, would you have planned the mission differently?
I don't think we would have done things very differently. You learn as you go in this business. And even if you're confident that your vehicle is going to last a very long time, you can't go dashing about in a way dramatically different from what we did anyway, because you have to get smarter about Mars as you go.

One thing that I always preach to my science team is ... "trust the vehicles." I really believed that these things were going to last a long time. Now, 300 days, 200 days, 150 days, what have you, I don't know. But I really believed that they were going to last for a long time, and we shouldn't operate them as if they were going to drop dead at any moment. We should be willing to plan ahead. We should be willing to take a risk and do something that may take a long time, that may not have a good payoff.

The best example of that was our drive to the Columbia Hills. Here we were on sol 90. The "warranty" had just expired on the vehicle, and we're two and a half kilometers away from this phenomenal-looking target. We've got no idea whether we're going to be able to reach it or not. We've got a choice: We can either believe in the vehicle — believe in its ability to go that far and last that long, and take the risk and just go sprinting across the plains — or we could just fool around with the rocks we have in front of us and say, "Well, we'll never get that far, so let's just focus on what we have here and be happy with it."

The commitment that we made on about sol 100 was, "Let's go for it." We went for it, and we got there, and we've been in the hills ever since. The really exciting science discoveries from Spirit didn't begin until sol 156, when we crossed the boundary into the Columbia Hills. So it was the right thing to do, and it paid off.

In the "Nova" documentary, there's a lot of attention given to the problem with Spirit early in the mission. Was that the huge turning point?
It was terrifying when it happened. I don't know if I would use the phrase "turning point," but it was one of the truly singular events of the mission. We came perilously close, I think, to losing that vehicle. In retrospect, we probably were not nearly as close as it seemed we were at the time. These vehicles have an enormous amount of smarts built into them. They're very, very good at keeping themselves safe.

What happened was, we fundamentally lost control of Spirit for several days. The vehicle was awake all night long, rebooting and rebooting. I don't know how much more of that the rover would have been able to take. But it was a terrifying thing.

And the timing was just intense. It was awful, because it was sol 18. Remember, Opportunity landed on sol 21 of the Spirit mission. So this is three days before Opportunity was going to land. We've completely lost the ability to control one vehicle, we've practically lost contact with it. The other one is screaming in toward Mars with three days to go, two days to go, one day to go. And we had duststorms in the Martian atmosphere, so the atmosphere we designed for was not the atmosphere that we got. We're making last-minute changes to our parachute deployment parameters and hoping this is going to work.

I'm sitting there on the ground, along with so many other people on this team, having put so much effort into this mission, and I'm thinking, "In 48 hours this could be all over."

The reality was, we got Spirit back, and there was just a bit of fantastic detective work by some of the software folks to figure that one out. Next day ... Opportunity lands successfully, we land right in this crater, there's layered bedrock and off we go. But I'll tell you, it was a dark few days.

Was there anytime when you were thinking, "Maybe this isn't such a good idea to have a documentary film crew this close to what's going on"?
No, I never thought that at all. In fact, I was glad to have them there. When something is a success, the way this has been, it's very easy for people to think, "Oh, well, it went smoothly, they knew what they were doing." And the sense of drama, the sense of science and engineering as it's really done, can be lost.

I think it's very important for those of us in scientific and engineering fields to be able to share with people, especially with young people who are making career choices, what our professions are really like, and how dramatic and how exciting and how terrifying these professions can be. To have someone there with the kind of eye for drama and detail that Mark Davis, the producer of the "Nova" episode, has — to have him there documenting these things as they happen — was a good thing.

We were going to see triumph, or we were going to fall flat on our face. At the time there was no way of knowing. But capturing that and having people be able to look at this and realize, "No, this wasn't by the script, by the book, by the numbers ... this was drama, this was excitement, this was scary" ... it conveys it as it really was. And I was glad to have him there.

Do you feel as if you almost have a couple of siblings here, and you're wondering "which one Dad likes best"?
They definitely have taken on very, very different personalities. When we built them, we built them as identical as we could. As we were testing them, when they were here on Earth and still growing up, even then they began to take on personalities. The reason for that is that Spirit was the firstborn. Every major, complicated test that we did, it seems we did on Spirit first.

The purpose of testing is to uncover problems, so we uncovered a lot, and most of them were on Spirit. So Spirit seemed like the problem child even back then. Once we got them to Mars, that trend continued. Spirit landed first, and that's the reason that Spirit was the one that had the anomaly. Had we landed in the opposite order, somewhere around sol 18, Opportunity would have had that terrible anomaly, because that was just out there waiting to bite us. We just didn't know it.

So Spirit has borne the brunt of being the firstborn, by being the one that uncovers so many of the problems. The thing is that, since we landed, we have used them completely differently. They're very, very versatile machines. I say these things are like Swiss army knives because of the different things you can do with them. And because their landing sites are so different from one another, we have tended to use them very differently. Because of that, I think they've diverged in personality, and in physical properties even more.

Spirit, I think of as being the tough, hard-working, blue-collar rover. Spirit's the one that had to drive four kilometers. Spirit's the one that had to climb into the Columbia Hills. Spirit is banged up, scratched up, dinged up. Spirit was the one that had the gimpy wheel for a while, though that seems to be getting better. Spirit has been the one that's really had the tough ride, and Spirit has had to work very, very hard for every major scientific discovery. Even the rocks are hard. You've got to grind really hard with the RAT [Rock Abrasion Tool] to get into them.

Opportunity, I call her "Little Miss Perfect." Everything's gone right for that vehicle. The vehicle comes to rest, and bang, there's layered outcrop — salty, sedimentary rock, 8 meters away. Literally the first picture to come down has got this outcrop in it. We just waltz right over to it, everything's there, the rock is nice and soft. You grind into it easily with the RAT. You get out onto the plains and it's like a parking lot. It's just smooth, hard-packed sand as far as you can see to the horizon — the most benign driving surface you can possibly imagine. Opportunity doesn't have a scratch on it.

Another thing that sets Opportunity apart, though, is that unlike Spirit, Opportunity has this stuck heater. Each of the joints on the arm has a heater on it, to warm it up. And on the shoulder joint on Opportunity, that heater has been stuck on since we landed. Now, we can take it offline at night by taking the battery offline, and we do that if we need to save energy. But this has been a significant power drain on that vehicle since the start of the mission. Fortunately, that has been the rover that doesn't have to struggle for many kilometers over boulders. ... I'll be honest with you, I think if you took Opportunity and put it in Gusev Crater, that rover would have had a tough time. It's a good thing that our tough, blue-collar rover ended up at the tough landing site.

Have you thought about how long this is going to go on? Are there other missions that you need to be working on?
This is what our highest priority will be until the very final day. For me personally, this is my highest priority. ... For example, I'm on the imaging science team for the Cassini mission to Saturn, and that mission is returning wonderful data. I have not been able to devote the time to missions like Cassini that I had expected to, because I have to give first priority to Spirit and Opportunity. That's just what I'm going to continue to do. Cassini is a very big mission with lots of good scientists on it. They'll be just fine. I gotta stay with my rovers.

Is there a particular date that the mission has been extended to?
What NASA's been doing is they've been giving us money in six-month chunks. So the last one came on the 1st of October. Every time six months come around, we renew it, and then we go on.

Has there been any thought given to what the longevity of this mission means for future mission planning — for example, the idea that we could have a permanent mission to Mars?
It gives you some hope that future missions that are intended to operate for long periods of time will in fact be able to so.

At the same time, the worst thing that you can do, based on a mission like this, is to take away the message that, "Oh, somehow Mars just got easy. Now we have Mars figured out. Sure, we had a lot of failed missions in the past, but now we've got it."

No. This mission has succeeded because a remarkable group of people worked very hard, and tested, and tested, and tested, and tested, and tested. In the end it comes down to blocking and tackling on every single mission. And it's going to be that way in the future.

In order to succeed, future missions are going to have to be as careful and as conscientious about testing as we were. And they're also going to have to have a little luck, just like we did.