An interview with Steve Squyres

Steve Squyres

[The following is the text of an interview with Steve Squyres, professor of astronomy at Cornell University and scientific principal investigator for the NASA Jet Propulsion Laboratory's Mars exploration rover project. The telephone interview was conducted by AAAS senior writer Edward W. Lempinen in two installments, on 2 August and 5 August 2004.]

In the spring and summer of 2003, Mars was approaching a point where it was closer to the earth than it had been in 73,000 years—it was clearly visible at the time. At the time, of course, you were the principle scientific investigator on the rover mission. Did you ever go outside and just look up at Mars? And if you did, what did you think?

It was before launch, and at that point in time if you went out around midnight or so, Mars would just be rising. It was very close to conjunction. To me, the thing that really strikes me is how different it felt to look at Mars then, and to go out and look at Mars in the sky now. It's a very different feeling. Despite the fact that it was near its closest approach in 60,000 years or something, it just looked impossibly far away. You know, the rockets were on the pad [at Cape Canaveral, Florida] or about to be. The spacecraft were on the pad or about to be. And we had no idea what was going to happen.

Launches are risky. Landing is incredibly risky. We were having all kinds of problems with the hardware—terrifying problems with the hardware, stuff that could've completely kept us from launching because we had fatal design flaws inside the vehicle, things that could result in us leaving a smoking hole in the ground when we got to Mars. We had all these problems we were facing and we would go out at night after a day of trying to solve these problems and Mars would just look incredibly distant. You'd sit there—I can remember sitting on the beach at midnight, looking at this thing in the sky. And realizing that two-thirds of the missions—two-thirds of the pieces of metal that we had flung at that thing—had failed over the years, or the decades. It just looked really, really hard.

Now I feel a little bit different. Mars is still a difficult place to do business, but having them succeed in the way that they have, and having them tell us what we now know about these places, Gusev and Meridiani—there are places on Mars now where you could put a human being down in a space suit and they'd open a visor and they'd look around and they'd say, 'Yeah, I knew it looked like this, I saw it in the pictures.' We've got these robots up there with 20/20 vision and we would instantly recognize the place. You could feel like, sort of like, you'd been there. With that kind of familiarity with two tiny places on the Martian surface, it feels different when you look up at it in the sky at night. It feels more…familiar.

Was there any hint in your boyhood, or in your student days, that you'd be doing the kind of work you're doing now?

When I was a kid I was fascinated by exploration. I read everything I could get my hands on about early exploration of the Arctic, the Antarctic, the deep ocean, places like that. I was fascinated by that. And since I grew up in the '60s and early '70s, I was always fascinated by the Mercury and Gemini and Apollo missions and all that, and followed them closely on television.

The other thing is that I really liked science and really loved mountaineering, mountain-climbing. So all of those sort of naturally led me toward a career that involved exploration. And in fact I initially went into geology as a field where I thought I could get paid to climb mountains, a way to do science outdoors with my boots on. And while that didn't work out, it did give me a taste for exploration, doing it myself, that was very appealing.

The problem for me with geology was that I found after studying it for a while that the geologists who had been working this planet for the past couple of hundred years had actually done a good job of figuring it out. And that's not to say there's not an enormous amount of geological science to be done and questions to be answered, but a lot of the big questions, like plate tectonics—being a part of the plate tectonics revolution in geology must've been just exhilarating. But by the time I was a geologist, that had been figured out.

What I was looking for was a blank canvas where there were big, fundamental questions that people just didn't know the answers to, and don't. Doing geological exploration on another planet, where no had ever been and which no one had ever seen before, that had tremendous appeal.

I understand, though, that there was a class in your undergraduate years at Cornell that just really brought you to focus on planetary science.

It was my junior year, my third year, and I was a geology major. I liked what I was doing but it hadn't really grabbed me. And there was this course on the results of the Viking mission to Mars; it was 1977, when Viking was just returning data, and it was taught by a professor at Cornell, Joe Veverka, who was a member of the Viking science team. He's the [astronomy] department chairman at Cornell now. So I signed up for the course. I nearly got thrown out of the class, actually, because I was the only undergraduate who had signed up for the class in a class for graduate students.

Because it was a graduate level course, we were expected to some kind of original research for our grade, for a term paper. About three or four weeks into the semester, I decided, 'Well, I probably ought to start thinking about my term paper,' because the whole grade is based on that one paper. And so I got a key to what they call the Mars Room—it was the place where they kept all the pictures that were coming back from the spacecraft. This is before CD-ROMs, the internet—we didn't have much in the way of digital data—and so these pictures were just printed out on big rolls of photographic paper and then they were in this room. So I walked in there figuring I'd take 15 or 20 minutes to go through some pictures and see if I can come up with an idea for a term paper. I was in there for four hours, and I came out of that room knowing exactly what I wanted to do with the rest of my life. I'm sitting there going through pictures in notebooks and seeing things that no one had ever seen before. Literally, at that point in time, there probably hadn't been more than 100 people who had actually looked at them. I didn't understand what I was looking at, but the beauty of it was, hardly anybody understood. It was new. It was different. It was the unknown. And I realized then that by sending robots to these different worlds, you can explore in a way that is exciting and intellectually satisfying, and that's what I wanted to do.

It strikes me, generally, that you have a very interesting relationship with Mars.

The relationship to Mars is the obvious one—I'm fascinated by the place. I'm in no way unique in that regard. Mars has fascinated lots of people, for centuries. But I've always been intrigued by it, primarily because, alone among the planets, it's the one place where you could imagine life really taking hold. Of course there's Europa, which is a moon of Jupiter, which is intriguing for the same reason. But of the planets, and especially the places you could go and study in a comparatively straightforward fashion, it's by far the most intriguing.

As far as the relationship with the rovers goes, I've got a very strong and continuously evolving relationship with both Spirit and Opportunity. Though it's funny to speak of a relationship with things that are after all nothing more than machines. But these machines mean a lot to us. They're machines that we worked on for many years. They're machines that are the embodiment of the hopes and dreams that some of us have had for decades.

More than that, they are our surrogates. I know that if there were any way for me to go to Mars myself, believe me, I'd do it in a heartbeat. But since that's not possible, we use Spirit and Opportunity as our eyes and our hands to explore Mars as we would have if we were there. The design of the vehicles is very intentionally, in some respects, human like.

We gave Spirit and Opportunity 20/20 vision. If you look at the resolution of the pan-cam cameras and you convert milliradians per pixel, the equivalent of human vision is 20/20. We gave them arms that are very similar in form and function to a human arm—that's because human arms is pretty well designed for the tasks that it has. We gave them the ability to move through the terrain just as we would if we were there, climbing up hills, going down into craters, going across the terrain to get from one interesting place to another. And so they do what we would do if we were there. And that fact, plus the fact that they have sort of developed personalities, leads you to have a relationship with them that's considerably stronger than one might have with any old hunk of hardware. They have their quirks, they have their own little peculiarities, and dealing with those on a daily basis, 12 hours a day, you start to feel pretty close to them.

Do you miss them?

It's funny, I do kind of miss them. Back when we were building them, we were working with physically in the same room with them every day. They had their quirks and their personalities back then, too, and you got to know them really well. And then when the rockets launched, of course, they were out in space for the first seven months of the mission, when they were just cruising to Mars and not really doing much, I really missed them. Now that they're on Mars and we're talking to them and working with them every day, it's a good feeling. But it's not quite the same as having them around. But you know, now they're off doing what they're supposed to do.

Back to the time you were at Cape Canaveral, in the spring of 2003—what were the greatest challenges that you seemed to face in those days? Were those the same challenges you'd expected in the earliest days of planning?

The challenges at that time broke down into two different types. There were the ones we knew were out there waiting for us on Mars. But then there were the ones we had to solve before we could even get off the ground. At that point in time the mindset was very much, let's focus on today's disaster, and save tomorrow's disaster for tomorrow. Because if we didn't solve the immediate crisis we were dealing with, we weren't going to fly at all.

I had problems with some of the instruments that my team was dealing with. I think by far the most severe problem we faced in the days before launch was we inadvertently blew a fuse inside Spirit. And in the process of investigating why that fuse had blown, the engineers had discovered a potentially fatal flaw in the pyrotechnics system on the vehicles, the system that fires the little explosive devices that release the solar array and release the arm and release the wheels and allow the vehicle to open up and deploy. There are dozens of these pyro-firings, these little explosive events that have to happen in the landing process, for example. And if any of them don't happen, you're done. We uncovered what looked like it might be a fatal flaw in the design of the pyro system, and in order to exonerate the pyro system, it was necessary to go to some extreme lengths. The engineers on both coasts, in Florida and California, had to perform heroic work to get that whole issue resolved. We didn't get the last issue resolved and the final go-ahead until three days before we launched.

It was terrifying—it was absolutely terrifying. If we had not solved that problem, those rovers could've ended up in the air and space museum instead. It was that kind of stuff—My God! We have to solve this problem or we won't even fly!—that we were really focused on at that time.

Now, the honest truth is, we launched these vehicles not really knowing how to operate them on Mars. We launched them without software that would work adequately on the surface of Mars. We knew how to operate them in flight. We knew how to launch 'em and we knew how to land 'em. Software for launch, cruise, landing was extensively tested and in excellent shape. So I would say at the time we launched that our confidence in getting them down safely onto the surface was high. Now, Mars can always bite you. Our landing system is a very robust, very rugged landing system, but that's not to say that one really strong gust of wind or one sharp, pointed rock at just the wrong place or time couldn't kill you—it could. There was an element of luck in it. But we were confident when we launched that we had done all the things that we needed to do to give us the give chance of a safe landing.

What we were not ready for at the time of launch was surface operations. We had a frantic seven months. People always had this sort of funny idea—people not on the project—that for crews, it might be kind of a quiet, relaxing time for us. In fact we had to pick up the pace after we launched because we had only seven months to complete the software for driving around on the surface and for learning how to operate these things. We didn't build two rovers—we actually built four of them. Two of them we launched to Mars, and two of them are here on Earth. And all through cruise we used those two rovers here on Earth to earn our Martian driving licenses. It was ugly.

We would have these operations readiness tests, where we would operate the vehicles for a week at a time as if they were actually on Mars—and they were horrible. We made every kind of mistake you could imagine. I think over all of the operations readiness tests all added together, I don't think the rovers moved more than about 20 meters. It was a very, very painful, laborious process to learn how to use these vehicles. But by the time we got them to Mars, we kind of knew what we were doing. And since then, we've learned a lot about what we're doing. So we're doing very aggressive things with them now.

Is there any single aspect of this mission that you can point to and say: This is the greatest success? This is the most important discovery?

You just asked two different questions—the greatest success, and the greatest discovery. If you look at this from a purely scientific standpoint, those questions are equivalent, but this is not a purely scientific enterprise.

This is science enabled by engineering and technology. Our greatest success on an engineering front is that we have really raised the bar for what we can do robotically on another planet. We have traveled more than three kilometers—in fact, if you add the two vehicles together, I think our total odometry is close to five kilometers now. We're climbing mountains, we're descending into craters, we're really pushing the boundaries of what people have ever done robotically on the surface of another world. And the technical accomplishments there, the fact that all of the scientific instruments are working exactly as they were designed to and are returning data flawlessly day after day after day—the technical achievement there is one that we are very proud of.

Scientifically, I think our most significant discovery has to be the evidence for pretty substantial amounts of liquid water at Meridiani Planum. What we have found there are rocks that bear the pretty distinctive signature of the action of water, chemically, in their texture. These are sedimentary rocks. They were laid down in water, affected by the action of the water, in some cases created by the evaporation of water. And this speaks of an environment in the past on Mars that, at one point in time at least, would have been a very life—friendly and very habitable environment. And that makes Mars a somewhat more interesting place.

At this point, based on what you know, do you think there was ever life on Mars?

You know, I don't have an opinion on that. I think one of the worst mistakes you can make as a scientist is to believe or wish for an answer to some question. It can skew your analysis of the data. It can bias your interpretation of results, wishing for something. It's maybe not a good thing to do if you want to find out what the truth is. And I don't have any data that to me point conclusively for or against it, the idea of there having once been or now being life on Mars. And so my inclination is to say, let's use the data we've got to formulate better experiments that may lead us to an answer to that question.

Spirit and Opportunity have proven much more durable than expected, no? Any sense of how much longer they'll go on?

I think that our prospects of surviving our first Martian winter are reasonably good, if nothing else gets us first. I don't think that we have any reasonable chance of surviving a second Martian winter.

So you think that this mission could continue for weeks, perhaps months. As this mission winds down, though, what do you think future directions of Mars exploration and research should be?

I think what you're going to see is a continuation of the plan NASA already has in place. The 2005 and 2007 missions are already solidly set in motion, and those are going to be what they're going to be. 2009 and beyond is when you have the opportunity to respond to some of our discoveries. I think it's fortunate though perhaps not entirely surprising that the mission that's planned for 2009 is already, in itself, a very good response to our mission. It's another rover mission, consisting of a larger, more capable, longer-range rover with potentially a nuclear power source that could go and really explore one or two places in great detail.

And then I think the next thing to do, in my opinion, and I think fortunately also in NASA's opinion, is to move fairly aggressively toward sample return. You can do wonderful things with in situ instruments. I'm a big fan of in situ science on Mars, that's what I do. But I've built enough instruments to go to Mars to know for sure that instruments that you can strap on top of a rocket and shoot off into space are never going to be as capable as things you can build and tend lovingly under laboratory conditions. And so getting some samples back and getting them back into the best laboratories on earth and taking them apart molecule by molecule is going to enable a whole range of science that you can't possibly do in situ.

The other thing about sample return is that, it's kind of a gift that keeps on giving. Once you've got samples back, if you don't immediately allocate all of them to destructive analysis, then if you keep some of those samples around, there are going to be new generations of instruments, new generations of scientists that are going to come along 10, 20 or 30 years later and still be able to apply what is then the state of the art technology to the samples from Mars. People today are doing lots of good science with samples that were collected from the moon in the '60s and early '70s. So, I think sample return would be a really good direction to go, once we're technologically ready to do it.

I assume that would be robotic missions—it wouldn't be manned missions.

Look, I would love to see us going into human exploration of Mars as soon as possible. But I think that it's quite viable to do robotic sample return.

Spirit, in late June, discovered a rock that's been named "Pot of Gold," and it received some press attention—

Oh yeah. It received a lot of attention from us, too.

You suggested at the time that your team couldn't readily explain how it was formed. Have there been any new developments in your understanding of what caused the rock to form as it did?

Not really.

Do you have any favorite theories about what caused the rock to form as it did?

We do have some theories. But I think that testing those theories really requires us to understand better the geologic context in which that rock arose. As we have worked our way up the Columbia Hills so far, we haven't seen anything that looked like that. I was thinking that it might be plausible that the Columbia hills might be chock-full of rocks that looked like that. And in fact, we really haven't seen anything else that looks like that. It's a very, very strange rock. And I think we need to understand the geologic context of the Columbia Hills better before we jump to too many conclusions about how that rock formed.

So you don't want to say what any of the theories might be?

You know, I'd rather not.

When this mission is over, whenever that happens, what will you do next? Will you stay in Mars research and exploration? Or will you move to other things?

I definitely will stay in planetary research and exploration. I don't expect to write another proposal to be a principle investigator on another mission, personally. Missions like this require an enormous degree of commitment, personal sacrifice by one's family members—I haven't seen my family hardly at all in eight months. And before that I was commuting once a week to the West Coast for years.

What I'd like to do is continue to participate personally in missions of planetary exploration where I can have a comparable amount of fun but not so much responsibility. I mean, seriously, what I'd like to do is find a place where I can contribute to planetary investigations in ways that make use of the experience I've gained in doing this mission—help other principle investigators put together some hardware to go to Mars or some other planet. Maybe I can be someone who can help them with the challenges they're going to face along the way, while not actually having to be in the role of P.I. myself. Something like that has a lot of appeal to me.

When that day comes—when this mission ends and Spirit and Opportunity are stuck on Mars, no longer able to function, what will your feelings be then?

That's going to be hard, I won't kid you. When these things die, it's going to be a painful moment for us. Again, they're not human, they're machines, but they are machines in which we've put a great deal of ourselves, and it's going to hurt when they're gone. You know, I—it's hard for me to predict how I'm going to feel, because I've never been through this. But it's going to be hard.

It's going to be a lot easier than it would've been otherwise because of the success we've had with these vehicles, because of their accomplishments. If these things had died on landing, or if they'd died early in the mission—for example, Spirit had that terrible anomaly, it started on the 18th sol, with the mission just barely getting started, if Spirit had died then, that would've been devastating, just a devastating loss emotionally. We're past sol 200 with Spirit now, we're close to sol 200 with Opportunity, and these are vehicles that were designed to last 90 sols. So whatever happens, when they die, they will have led long, productive lives—far beyond our expectations—and will have died honorable deaths. And in a situation like that, sure, it will hurt, but I don't think it will be nearly as bad as if they'd died young.

One other thing to mention—it's enormously satisfying right now to be doing the things that we're doing with these vehicles. We are absolutely using them to their utmost. We are pushing them to their very limits. I'll give you just two examples from the last 48 hours. A couple of sols ago, with Spirit, there's something on the vehicle we call the tilt high-water mark—it's just a continuously measured value for how much the rover is tilted. On Spirit, a couple of days ago, we hit a tilt high-water mark of 34 degrees—it was tilted 34 degrees. We're doing rock-climbing with this thing now. We're traveling over incredibly rugged difficult terrain. We're pushing that vehicle to its limit.

I'll give you another example of Opportunity, just last night [4 August 2004]. We have a UHF antenna on board the vehicle. It's sort of an omni-directional antenna in that it covers the whole sky. We use it to communicate with the Mars Odyssey orbiter when it flies overhead. Despite the fact that it's sort of omni-directional, it's not really, because there's some directions where it works really well and some directions where it works less well. Something that we've been doing for a while is when the Odyssey is gong to be flying across the sky, we can predict of course ahead of time where it's going to be in the sky. And so what we've been doing over part of the mission anyway is that we've turned the rover and we park it so that when the orbiter flies over, it'll be at the best possible attitude, so the orbiter will pass through the fat part of the antenna beam.

We did something yesterday, for the first time, where as the orbiter is flying across the sky, we're sitting there on Mars, the Odyssey spacecraft pops up over the horizon, and in about 15 minutes as it flies from horizon, we actually, as the spacecraft is flying overhead, slowly turn the rover, rotating to point the fat part of the antenna pattern at the spacecraft continuously, as it works across the sky. And so instead of getting 80 megabits down to the ground, we got 130 as a result of doing that. It's just really cool stuff. And every day we're finding new tricks to teach these things and new things that we can do to squeeze more science out of them.

It's enormously satisfying to be able to take two pieces of hardware that—once upon a time, oh, we babied these things. We dressed up in fancy white suits and we wore rubber gloves, and we tiptoed around them delicately and we treated them like they were 24-carat gold. And now we're just beating on them! [Laughs] And they're responding well. They're scratched up, they're pretty beat-up rovers now, but boy, they're doing great. It's really really cool to see them responding so well to the aggressive things that we're doing to them in the environment on Mars.

I have to think that that will have a strong influence in the development of a new generation of rovers.

Absolutely, you bet. It teaches the people a lot, too—the next generation of scientist and engineers. We've got a lot of students on this mission who are learning a lot of tricks about how to explore other planets.

I'm afraid with that I'm going to have to go. We're having a meeting to plan tomorrow's activities for Opportunity and I have to go off to that meeting…

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For more information, read the related article.

See also the team's papers and Mars photos.