Water On Mars
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JEFFREY BROWN: At least part of Mars was once “soaking wet.” NASA scientists announced that today, after studying data from the rover Opportunity, which landed five weeks ago in a small crater on Mars. Here to tell us about the finding is Jim Garvin, lead scientist for NASA’s Mars program.
Welcome to you.
JIM GARVIN: Thanks, Jeff.
JEFFREY BROWN: Before we go through all the evidence, in simple terms what exactly have you found?
JIM GARVIN: We found evidence, Jeff, that rocks on Mars at this site were once soaked in liquid water, leaving behind the clues in the chemistry of those rocks. This points to the possibility that within those rocks at some time in the Mars past we could have had habitats, places hospitable for short periods of time or long periods of time to life as we know it on Earth.
JEFFREY BROWN: Habitats habitable to life as we know it on Earth.
JIM GARVIN: As we know it on Earth.
JEFFREY BROWN: But you did not find yet actual life or signs of life?
JIM GARVIN: Not at all. We’re not even directly looking for it. We’re looking for records of times environments that would have been good places to live if you were on Mars.
JEFFREY BROWN: No question, though, about the excitement in this for you.
JIM GARVIN: Oh, my gosh. This is beyond a home run. Greater than anything we had expected this early in this kind of mission.
JEFFREY BROWN: Now, is there any way of knowing when there would have been water?
JIM GARVIN: That’s the challenge. We don’t have the tools built into our rovers to ask that directly. So we have to do it by inference. As we move around beyond the outcroppings we’re looking at, by looking at the extent of the stack of rock rocks and how much of them were processed by the water, we’re seeing the evidence of from the past and we may be able to get some clues to that, and maybe by also comparing to our Gusev site, where Spirit is working. But the direct evidence may require returning those rocks to labs here on Earth to get the timing down really tight.
JEFFREY BROWN: Actually bringing them home.
JIM GARVIN: Bringing them home with robots.
JEFFREY BROWN: Now, another big question that was raised at the press conference today was that it’s not clear whether the rocks were actually formed by bodies of water. Explain to us what the issue is there.
JIM GARVIN: Very important point. We would love to find that all these outcroppings that we see at the Opportunity site were actually laid down by water, the way rocks are made when lakes produce sediment and then dry up, or ancient seas. We’ve seen that all over the Earth. You can find it in west Texas, all over. We’d love to know that. That means water was there for long enough for both life to exist, but also even maybe for life to get its start. We think those warm, wet environments for a long time are the right conducive places.
We haven’t found that yet. We’re still looking. We have a plan. There may be evidence, a little hint, that we might be able to get with this machine, with this rover Opportunity to find that. But right now, all we know is the rocks we’re looking at were soaked with water, producing these chemistry… these minerals that tell us it was wet in the rocks.
JEFFREY BROWN: Okay, we have some pictures that help us walk through the evidence here. Let’s look at the first one. It’s a wide shot. Tell us what we’re seeing.
JIM GARVIN: We’re looking at this outcropping, the first bedrock seen on another world. We never even got to touch that kind of stuff on the moon. Here we are on Mars, 30, 40 feet away from where we landed. We’re driving up and exploring bedrock not much higher than a big curb side. So this is not a huge vista. The total relief is about six feet, the size of a human being like yourself.
JEFFREY BROWN: Six feet is all we’re looking at.
JIM GARVIN: Right, six feet. We’re in a little hole. Tiger Woods would have been really happy with this. We went all the way to Mars, multi-hundred millimeter, and we landed in a 60-foot hole.
JEFFREY BROWN: That turned out to be good fortune.
JIM GARVIN: Very good fortune.
JEFFREY BROWN: Let’s look at the second picture, which is zooming into a specific formation called El Capitan.
JIM GARVIN: We nickname these places so we can keep them straight. This is El Capitan. This is about the scale of what I’m holding up here. It’s an outcropping with a foot or two of relief. What you see are layered rocks, finely layered, fairly soft. We can scratch them with our rock abrasion tool and grind them away very easily, kind of like wet limestone. You see layering and cracks. If you look carefully, you see little spherical things — little BBs, if you will. They’re not BBs, of course. They are evidence of little rounded things made by Mother Nature on Mars.
JEFFREY BROWN: Here’s a picture of that. You’ve nicknamed these blueberries.
JIM GARVIN: Because when we put the pictures together in false color, they turn out blue. They’re really gray berries, if you got technical. They’re about the size of a BB, like I said, a little pea. They’re distributed in these rocks. They’re not just along layers like someone spilled them out. They’re distributed. One possibility for these — of many, the one we’re feeling more confident about now — is that they are in fact the signs of fluids filling little holes in rocks and then solidifying, growing new kinds of little pieces of rocks, and something we call in geology concretions.
JEFFREY BROWN: Opportunity found an astonishing amount of salt. What does that tell you?
JIM GARVIN: Well, salts as we know on Earth, places like the Dead Sea, Death Valley, are a sign often of a former wet environment. Liquid water wet. If you ever swam in the Dead Sea, you see all around the bathtub rings of the Dead Sea, encrustations of salt. Here on Mars we found salts made of sulfate like the kind of stuff you would see if you went to White Sands, New Mexico. That’s a sign that the chemistry, the water had to have been around long enough to convert into this salt-rich stuff. That’s a good indicator, a telltale of water soaking the rocks.
JEFFREY BROWN: Now we have another picture of something called vugs.
JIM GARVIN: That sounds like a crossword puzzle word.
JEFFREY BROWN: Doesn’t sound very good but what is it?
JIM GARVIN: Vugs are little voids, gaps in rocks– millimeters as fine as my fingernail where crystals, neat crystals, maybe the kind you’d find in dry lake beds on Earth, used to be there and weathered out. They were removed by a process maybe involving water. That process of removal gives us this scattered buggy appearance we see. That’s a telltale. That’s a fingerprint. Sherlock Holmes would say water was there, made the stuff. It’s gone. That’s what we see now at this hand-lens scale on the rocks.
JEFFREY BROWN: You’re taking all this physical evidence and the chemical evidence you’re able to find and put it altogether.
JIM GARVIN: Right.
JEFFREY BROWN: What happens next?
JIM GARVIN: We put it together and put the puzzle together — we say water, soaking rocks. What happens next is, we start exploring beyond the little hole we landed in, this little 60-foot cavity, 6-foot deep. We look beyond the outcrop of what’s ahead.
JEFFREY BROWN: We have one more picture.
JIM GARVIN: This is what’s ahead. We’re really exploring and adapting to Mars. What you see looks like a small set of hills, another crater, a week’s drive away. If you look across there, the surface is so flat, it’s almost like a frozen lake surface in rock. On the distance, you’re looking at the back wall of a big hole 100 feet deep. We think we see, possibly, outcroppings of more rocks that might give us a greater cross-section of the Mars we need to explore.
JEFFREY BROWN: Okay. We’ll stay tuned. Jim Garvin of NASA, thanks very much.
JIM GARVIN: Thanks a lot, Jeff.