Roving Mars

squyres
Steve Squyres
Credit: Cornell

The Mars Rovers Spirit and Opportunity are the Energizer Bunnies of planetary exploration. Designed to last for only 90 days, they are still going strong after nearly two years. Their journeys on Mars have provided exquisite detail of the planet’s surface, proving definitively that liquid water once existed on this now arid world. Just when the scientists thought the rovers were finished, their solar panels blanketed by so much dust that power levels were dropping lower and lower, Mars came to the rescue by sending dust devils spinning nearby, blowing away most of the dust. It is almost as though Mars itself was rooting for these two little intrepid rovers, wanting them to further explore the planet’s manifest mysteries.

Steve Squyres, the Principal Investigator for the Mars Exploration Rover (MER) project, has now published a book about what it took to get to Mars. His tale begins with the glimmer of an idea, and then follows his travails through NASA’s bureaucracy and the construction of the rovers. He recalls the exhilaration and anxiety of launching from Earth and then landing on Mars, and concludes his saga with the rovers still in full exploration mode.

The following is excerpted from "ROVING MARS" by Steve Squyres. Published by Hyperion. Copyright 2005 Steven W. Squyres. All rights reserved. Available wherever books are sold.


"When I was a kid, I loved maps. Still do. I grew up in the sixties, and in those days if you looked at a not-so-current atlas of the world, you could still find a few blank spots-places that were understood poorly enough by the mapmakers that they didn’t know what to draw. I loved the idea of a map that wasn’t done yet, with places on it still to be discovered. As a boy, I read everything I could get my hands on about exploration-Amundsen and Scott in the Antarctic, Beebe and Barton in the deep sea-tracing their adventures across my maps and dreaming about the exploring I’d do myself someday.

rover_slip
The path of Spirit along the floor Gusev Crater to Columbia Hills as seen by the navigation camera
Credit: NASA/JPL

By the time I hit college, reality set in. There were no blank spots on the maps anymore. I was a student at Cornell University, in upstate New York. I loved climbing mountains and I had a knack for science, so I picked geology as a major, thinking that it might be a way to get paid to go climbing. After learning a little bit of geology I started to drift toward something involving exploration of the sea floor, since there were still some blank spots there. But it wasn’t working for me. The geologists who have spent the last two centuries studying our planet, it turns out, have done a pretty darn good job of it. To me, geology felt like filling in details.

Then, early in the spring of my junior year, I was giving my girlfriend a tour of the Cornell campus. This was in 1977, just after NASA’s Viking spacecraft had arrived at Mars, and while we were in the Space Sciences building she spotted a three-by-five card tacked to a bulletin board, announcing that a professor who was a member of the Viking science team was going to be teaching a graduate seminar course on Mars. What the hell, I thought, and I went.

I started by nearly getting kicked out of class. The first thing the professor asked when we were all in our seats was -Are there any undergraduates here? One timid hand went up – mine – and he asked me to see him after the lecture. It was pretty obvious he was going to throw me out. What saved me was that one of my would-be classmates was a grad student from the geology department who knew both me and the prof, and who came over at the crucial juncture and vouched as best he could for my studious nature. The prof assented, though not without making it clear why he didn’t like having undergrads in the course. If I’m talking about temperatures on Mars,’ he said, I don’t want to have to stop and explain to the whole class what thermal diffusivity is.’ I nodded sagely, and ran back to my dorm room to look up thermal diffusivity.

pancam3
False color view of shading differences between soil near the Spirit’s location.
Credit: NASA/JPL

Because the course was taught at the graduate level, we were expected to do some kind of original research project for our grade. A few weeks into the semester I figured I’d better start thinking about what I was going to do for my term paper, so I asked for a key to the -Mars Room, where all of the new pictures from the Viking orbiters were being kept. I found the Mars Room in Clark Hall, behind the Space Sciences building. It was a deserted and disorderly place, more like a warehouse than a scientific data archive. A few of the pictures that had been taken during the earliest part of the mission were in glossy blue three-ring binders, arranged in chronological order on gray-painted steel shelves. Most, though, were on long rolls of photographic paper, stacked on the floor or still in their shipping cartons. My idea had been to spend fifteen or twenty minutes flipping through pictures, hoping to find inspiration for a term paper topic. Instead, I was in that room for four hours, racing through the pictures, stunned. I understood almost nothing that I saw, of course, but that was the beauty of it. Nobody understood most of this stuff. In fact, only a handful of people in the world had even seen it yet. Sitting there cross-legged on the linoleum, I was exploring a new, distant and alien world. I walked out of that room knowing exactly what I wanted to do with the rest of my life.

The planet that I saw in those pictures is a beautiful, terrible, desolate place. It’s cold: The average temperature on Mars is sixty degrees below zero centigrade. It’s dry: If you could take all the water vapor in the martian atmosphere and freeze it out on the planet’s surface, the layer of ice you would make would be barely a hundredth of a millimeter thick. The thin carbon dioxide atmosphere of Mars whips dust off the ground into storms that can darken the skies for months at a time. The planet that we see as a shining red point of light in the night sky of Earth is a barren, hostile world.

Mars Opportunity Cloud Cover
Opportunity found ‘blueberry-like’ concretions scattered across the Meridiani plains. Click image for larger view.
Image Credit: NASA/JPL

But it may not always have been that way. The pictures I was looking at, though I did not realize it then, showed evidence that water may once have flowed in abundance across the martian surface. There are dried-up riverbeds on Mars. There are dried-up lakebeds. There are features that tell of enormous floods that once poured across the martian surface. Most remarkably, there are small valleys, with branching tributaries, that wind sinuously through the martian highlands. These valleys must have been carved by streams that were so small that it’s hard to imagine how they could form under the frigid conditions on Mars today. How can a trickle of water flow at sixty degrees below zero and not freeze? But there they are, in the pictures, demanding explanation.

Most of Mars’s water-carved valleys are exceptionally old. It’s tough to be sure, but many of them may date from the first billion years of Mars’s 4.5-billion-year history. So despite the planet’s forbidding climate today, its valleys are a clue that back in the earliest part of its history, Mars may have been a warmer, wetter and more Earth-like world.

And here’s the thing: Four billion years ago is the very same time that, somehow, life first came into being on our own planet. We don’t know how this miracle-the process of genesis-took place. But one thing that it surely required was liquid water. And if it happened here on Earth four billion years ago in environments that were warm and wet, then an obvious question arises: Could it also have happened on Mars?

Finding evidence that life arose independently on another planet would be one of the most profound discoveries that humans could ever make. If you only know that a miracle has happened once, then it may be a rare, or even singular, event. But if you can prove that it happened twice in the same solar system-recognizing that there may be countless solar systems out there-it means that, while no less wondrous a miracle, it may be a universal one.

Opportunity ruts
Opportunity hazcam view of its dune hazard and deep ruts. Banner image shows recent picture of the Earth as viewed from Opportunity on the surface of Meridiani Planum, Mars.
Credit: Cornell/JPL/ NASA.

So Mars is a world that can help us learn our place in the cosmos. If we go to Mars and find that it developed life, we’ve learned something fundamental about how common a phenomenon life may be. And if we go there and find that the conditions were once warm, wet and habitable, yet that somehow life didn’t emerge, then we have learned something profound about the conditions that are required for life to develop.

And consider this: Suppose just for a moment that the miracle of genesis really did occur on Mars. On Earth, because of the intense geologic activity that our planet has suffered since its birth, the physical evidence of how that miracle took place is gone. That the miracle occurred is inarguable-we ourselves are part of the evidence. But tangible clues of how it actually happened are lost to us forever, because all the rocks from that earliest period of the Earth’s history have been destroyed by later geologic activity. On Mars, though, they have not. Mars has been a more geologically quiescent world than Earth, and nearly half the martian surface is covered with rocks that are close to four billion years old. So if the miracle of genesis also took place on Mars, then evidence for how it happened may still be there, a story in the rocks waiting to be read.

The business of reading the story that rocks have to tell is the work of a geologist, and that was a subject I had learned something about. A geologist is like a detective at the scene of a crime. Something happened here long ago . . . what was it? Was it warm here? Was it wet? Was it the kind of environment that would have been suitable for life? The answers to questions like this can lie in clues that were left behind in the ancient rocks on the planet’s surface.

mars_rover
Rover impact simulation video frame. Each rover could bounce twenty or more times before coming to rest, with the average impact of a golf cart being dropped from the roof of a five-story building.
Credit: D. Maas/NASA/JPL/Cornell

Every rock preserves evidence of what conditions were like when it formed. When sediments are deposited, the coarse grains settle close to shore and the fine ones in deeper water. Look at the grain size in a sedimentary rock, then, and you learn something about where it was laid down. Ripples preserved in rocks can tell you about currents. Distinctive minerals like salts can tell you what was dissolved in the water. A good geologist can piece together clues like this to learn in detail what an ancient world was like. Geology on Mars, if there was a way to do it, would be something worth devoting a career to.

But the kind of Mars mission I wanted to do would be complicated. It wouldn’t be enough just to fly by the planet, say, or to put something into orbit around it. Orbital spacecraft give you a great view, and they’re the best way to get a really global look at another world. But the problem I wanted to attack wasn’t a global one. The clues that I felt I needed were locked up in the rocks at a few special places on Mars. The only way to get at them, I was sure, was going to be the old-fashioned bang-it-with-a-hammer approach of a field geologist – albeit a robotic one – down on the martian surface.

And there was another thing about getting down onto the surface of Mars. Taking pictures from orbit didn’t feel like real exploration to me. Lewis and Clark hadn’t looked down on the Louisiana Territory from orbit. What I really wanted, when you got right down to it, was martian dirt on my own boots. And if I couldn’t have that, I wanted the next best thing. I just didn’t have any idea how to go about it.

Twenty-six years after my cathartic moment in the Mars Room, twin robotic explorers named Spirit and Opportunity were in final preparation for launch from Cape Canaveral in Florida. Built by a sprawling family of engineers and scientists, they were poised to carry the dreams of their creators to a planet where two out of every three spacecraft missions had ended in failure. Their mission was to study rocks on the surface of Mars, and to learn from those rocks whether or not the planet had ever had what it takes to support life.

That they were in Florida at all, however, was a small miracle."


Related Web Pages

JPL Rovers
Spirit’s Sol images and slideshow
Opportunity image gallery and slideshow
Mars Berries Once Rich in Iron-Water
NASA’s RATs Go Roving on Mars

Water Signs
Microscopic Imager
Gusev Crater
Pancam- Surveying the Martian Scene
Mössbauer spectrometer