People of IPR
Fri August 10, 2012
After 'Terror,' Mars Scientists Plan Exploration
IRA FLATOW, HOST:
This is SCIENCE FRIDAY, I'm Ira Flatow. Unless you've been hiding under a rock on Mars, you know that last weekend NASA's Mars Science Laboratory safely made its way down to the surface of the Red Planet and now the Rover Curiosity sits, set up camp in Gale Crater.
So what'll it do now that it's there? Joining me now to talk about it is John Grotzinger. He's project scientist for the mission, professor of geology at Caltech. He joins me from the JPL Campus in Pasadena. Welcome back to the program.
JOHN GROTZINGER: Thanks for having me, Ira.
FLATOW: Can you give us a status update and a thumbnail of what's going on now?
GROTZINGER: Well, at this point right now we're almost a week into the first surface mission operations. Everything is going 100 percent, and the science team is just thrilled with each passing day. It's looking really great.
FLATOW: And how soon does it make its first move off its spot?
GROTZINGER: Well, that's still a ways to come. In contrast to previous Rover missions, Curiosity is just so much more complex as a result of the design to integrate these 10 science instruments that we have to wait and we check each one of them out. In fact, yesterday we got the final bit of news that every instrument is alive.
We've done health checks and checked out some capability, but there's still a lot more to do until we're sort of firing on all cylinders and ready to start roving.
FLATOW: Tell us about the spot where it's sitting. I'm reading your biography. I've followed your career. You're a geologist, you love to study ancient forms of life, how it might have evolved. Are you in a good spot there, as opposed to past missions, which just wanted to get something down on the surface, you know, to get to Mars? Are you in a good spot that you'd like to be in to study these things?
GROTZINGER: Yeah, I think we're really in quite a great spot, actually. What's one of the points that's worth really emphasizing is that as a result of this entry, descent and landing system, which was so spectacular to see and be part of, it gives the science community for the first time in any of these landed missions access to the very top candidates.
So as we came down to the final four and then the eventual selection of the Gale Crater landing site, there were no duds. They were all a list of superlatives. And this one in particular, as we sit on the ground now, we honestly couldn't imagine a better place to have landed within the ellipse to begin our mission of exploration.
FLATOW: And why is that?
GROTZINGER: Well, the - I would suppose it's the context that's provided by the knowledge that we had an advance, that the Rover is now sitting at the base of a feature that geologists call an alluvial fan. And what that is, is it's a deposit of sand and gravel that's created by the erosion of mountains and transported by streams. For example, in the Death Valley area, people are used to seeing pictures of these cone-shaped deposits extending out into the valley.
And we seem to have landed right at the base of one of those, which is really nice because water is one of our key tracers for the search for habitable environments. Water flows downhill, and we're downhill.
FLATOW: So it is a given that you expect to find some trace of water or a sign that it was there, or could life still be there?
GROTZINGER: Yeah, there's still several things that have to go right, but the indicators that we see from the orbiter data suggest that we're off to a start position that's as much as we could have hoped for. One knows based on previous experience with Mars missions that you get ideas from orbit, and when you get on the ground, everything changes.
So with that caveat, however, the new generation of information that all the Mars orbiters provides is so helpful for creating a context. We feel pretty confident that we'll find something that has to do with water.
FLATOW: And how about something that might have to do with life or former life? I know you're an expert in stromatolites, which are sort of globs of sandy rock formed and held together by films of bacteria in shallow water. And you've also talked about the fact that there may not have to be life forms that form these things.
But I imagine you must be very excited by the fact that maybe these kinds of things might be nearby, and you might find something like that?
GROTZINGER: Yeah, I think that the - you know, of course we're holding our breaths in advance of approaching the first outcrops to imagine what might be there. And the one thing about Curiosity is that it was designed really not to do life detection; that's really a very separate mission concept. You know, Viking attempted to do that, and we have no way to detect microbial respiration, we have no way to look for micro-fossils.
If something like a stromatolite popped up, you know, that would be a thrilling discovery, but short of that, what we're really doing is sort of addressing the intermediate step of trying to find what we would call a habitable environment, a place that has water. All life as we know it need water. Energy. All microorganisms require a source of energy for metabolism. And a source of carbon, because all life as we know it is based structurally on carbon.
So with our payload, we're able to address each one of those systematically, looking at the chemistry, mineralogy and eventually in the most promising places take a shot at looking for carbon.
FLATOW: Take a shot looking for carbon, 1-800-989-8255. Sam in Wichita. Hi, welcome to SCIENCE FRIDAY.
FLATOW: Hi, go ahead.
SAM: Yeah, I was just wondering, I keep hearing about both the Mars Science Laboratory and the Curiosity Rover. I was wondering what exactly is the distinction between the two.
GROTZINGER: Oh, great question. The Mars Science Laboratory is the mission. So when we architect and develop a mission, it has several components associated with it, and it begins already with the launch vehicle at Cape Canaveral, the Atlas 541 rocket that lifted us off on last November 26.
Then on the flight from Earth to Mars, we have what's called the cruise stage, which provides solar energy to keep all the electronics going and also communicate with the Rover, which is nestled inside of what's called the aeroshell.
Then when we enter the atmosphere, we reject the aeroshell, and you're now all familiar with the EDL sequence. And then ultimately what gets deployed to the surface of Mars is the Rover. And the Rover, we actually regard it as a - as the fourth spacecraft. You have the launch vehicle, the cruise stage, the sky crane, and the Rover as the fourth mobile element.
FLATOW: And tell us about the instruments, the different kinds of experiments you can perform in that laboratory.
GROTZINGER: Right, so Curiosity is really pioneering in the sense that it's a mobile laboratory. We have to look all the way back to Viking to find a mission that we would say had a laboratory on board. The advantage we have this time around is that we can drive around and go to the features that are the most interest.
So within it, you know, we start off with what we call the remote sensing suite of instruments, which include the cameras, and there are 17 of them on this mission. And then we have a really kind of exciting new technology called ChemCam, which is a laser that shoots out in front, up to about seven meters away, that can create a plasma.
We look at the light, and it tells us about rock composition. And then we have the instruments that are on the arm, where we can reach out and get a more precise chemical analysis. We can use what's kind of like a jeweler's loop, a hand lens to get detailed color images.
And then just to single out a few more, in the belly of the Rover are what we call the analytical instruments that define it as a laboratory, and one of them is an instrument called X-ray diffraction. It's a - CheMin is the name of the instrument. We dump a rock powder in there, analyze it, and it gives us once and for all the definitive mineral composition of Mars.
And then the other one is called SAM. It stands for Sample Analysis at Mars, and it has a very complex suite of instruments that can do everything from sniff the atmosphere for methane to process rock powders and look for organic molecules and other advanced geochemical measurements.
FLATOW: 1-800-989-8255 is our number. As you drive around, is it possible - here on Earth people see - they go - if they're in a crater or a hillside, they can see the cut of the side of the mountain and see different strata and layers and different - the geological history. Can you do that on - from this crater on Mars also and find a good layer that you say, oh, I want to drill into that one?
GROTZINGER: Yeah, that's a terrific question and I think really defines the core aspect of the geological part of the mission here. It takes two things to be successful. One is a fully functioning science payload, and we seem to be well on track towards that part. The images we get now suggest that we're well on track for the other part.
But from orbit, we could already tell that as we approached this mountain in the middle of Gale Crater that we informally refer to as Mount Sharp, that there's a succession of layers that are five kilometers thick, so that's a bit over three miles. And it's almost three times as deep as the Grand Canyon. And what we learned ever since the time of John Wesley Powell's pioneering trip down the Grand Canyon, staring up at the walls of the canyon and wondering what those layers preserved, I think we're doing the same thing.
We look up at this, and we can only imagine that this represents a tremendous swath through the geologic history of Mars, its early environmental evolution of what might be tens, hundreds, maybe even a billion years, hundreds of millions of years to a billion years. And that interval of time that we're sampling occurred somewhere between three and four billion years ago.
So we're for the first time really probing the next dimension of Mars exploration, which is the dimension of deep time.
FLATOW: And how would you go about actually finding water if it was there?
GROTZINGER: So if you imagine now this stack of layers or, you know, hiking up the flank of the Grand Canyon, we have a very systematized method of exploration because of these layers. We simply start at the bottom, and they're going to represent the earlier chapters in the history of this environmental story.
And as we go up, we go to the younger layers, which - or the higher layers, which represent the younger chapters. And at each layer we will use our remote sensing package first - the cameras, the ChemCam instruments, zap it, see if it looks promising - and if we find a layer that does look promising, then we can reach the arm out and do a more sophisticated set of detailed observations.
And then based on that, if it really looks promising, we can drill a hole into it, generate the powder, and dump it into the instruments.
FLATOW: We're talking with John Grotzinger, who is project scientist for the Mars Science Laboratory Mission. We're going to take a break. Our number 1-800-989-8255. We'll come back and talk more with him. And you can also tweet us @scifri. Stay with us, we'll be right back after this break.
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FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY, from NPR.
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FLATOW: This is SCIENCE FRIDAY, I'm Ira Flatow. We're talking this hour about Mars, exploring Mars with the Curiosity. My guest is John Grotzinger. He is project scientist for the Mars Science Laboratory, also known as Curiosity. He's professor of geology at Caltech. Our number, 1-800-989-8255. Question for you, John. How much of the route is already planned out? How much leeway is there for you to say hey, let's see - you know, let's go over there and drive in that direction?
GROTZINGER: From that point of view, it's all open. We do have a route to a sort of a rough degree that we feel will take us from where we've landed in the ellipse to the base of Mount Sharp, where we'll begin to tear into that stratigraphy there, the succession of layers that we'll analyze.
But if we find something that's really exciting, you know, this is a mission of discovery, and if it takes us in a different direction, then we'll follow that for a while, and if it keeps developing, we'll spend more time on it. If it doesn't work out, then we'll just return to our original path.
FLATOW: 1-800-989-8255. Brad in Paradise, North Carolina. Hi, Brad.
BRAD: Hi, Ira.
FLATOW: Hi there.
BRAD: Hey, I was wondering what drove the decision at NASA to pick this location to touch down, maybe to get - to elaborate a little bit here.
FLATOW: OK, good question. You talked about it a little bit. John, give us a little more of your thinking.
GROTZINGER: Yeah, so basically the way that it works is we have to go back almost six years now and imagine that what NASA does is they open up a kind of an offering of potential candidates for landing sites. They define the mission and define the instruments that are going to be on it, and then they ask the world: Hey, where should we send this thing?
And five, six years ago, in the first round, anybody can show up and participate in the process. You give a presentation on a patch of Mars that you think is particularly interesting and be influential to the audience that's listening to it. And this process is iterative. So after each meeting, it gets trimmed down to a fewer, fewer number of candidates.
And as a result of this process, we would up with sort of the final four, if you will. And then the science team that's responsible for the mission, and there are over 400 of us, then deliberate, you know, how well does each one of these landing sites fit what we think are the goals of the mission as designed by NASA and our ability to achieve them with the instruments that we have. And on that basis, we wound up at Gale Crater.
And then after that, the entry, descent and landing engineers at JPL look at where the science team wants to go as their top priority and then tries to take the landing ellipse and shift it around. They literally slide it around and try to find the optimal position to avoid rocks, to avoid steep slopes, maybe a little cliffs here and there, other things that are considered to be hazards for landing. And then they pick the optimal position for them that represents the optimal position or the best possible position for the scientists.
FLATOW: How were you able to hit the bulls-eye? What is there about the new technology between now, six years ago, whatever, that allowed you - I mean, no pilots on board, robotic, flying on its own. How did it get exactly where - it's just amazing to we laypeople to understand that. You know, we see in the military that they're able to hit bulls-eyes with all kinds of things. How is NASA, how are you folks able to hit that bulls-eye so well?
GROTZINGER: Yeah, it does - it does seem like there's a lot of stuff that is missing there, and I think for those of us on a science team, it does seem like so much of a miracle. You hear about this. You see it. You can see the smaller size of the ellipse. You can see that they can get the ellipse closer up to the base of Mount Sharp and put it near the base of this alluvial fan, kind of in the sweet spot that we could ever want to be in.
And you just wonder: Is it ever going to work? And then in the end when it does, you realize that these guys are just seriously good at what they do. And the two components, if I can single out two things to just discuss briefly, between the previous missions is that this mission has what's called guided entry.
And so after the point of a cruise state separation, when the aeroshell begins to feel the tug of gravity and get pulled into the upper atmosphere, it has ejectable ballast. And that ejectable ballast, it offsets the center of mass from the center of symmetry of the aeroshell, and it literally flies through the atmosphere like a wing.
And then there are thrusters, what's called a reaction control system, and the onboard inertial navigation system detects changes from the direction that you're supposed to be flying in in order to arrive at the target that you've selected in advance. So it sort of flies out of these errors.
And then later on, after the parachute deploy, when we break free in the descent stage, it's flying around and then eventually with the sky crane, it also navigates, and it is able to fly out of its errors to basically get us down within about a mile and a half of the actual target. It was just amazing to see where we wound up.
FLATOW: So it actually has a map in its mind that it's following, and it compares it to the contour of the surface, where it is, and can decide I'm off, I go left, I go right, up, down? Sort of like that?
GROTZINGER: Right, exactly right that. You define the target. You give it the exact latitude and longitude and the position you want to be in, and then as you enter the atmosphere, right before that happens, on Earth we send it an update of the position of where it is before it enters the atmosphere, and defining those two in advance and then relying on the guided process, it does it all by itself.
FLATOW: You know, we have followed the two little rovers on Mars now for many years. And that was supposed to be, you know, a 30-day tour or something like that. And you've set up for - and now they're at, what, seven years, something like that? And you've set up for a two-year tour, which if we talk about in Rover years would be 14 years or something like that.
FLATOW: Are you ready - you know, all set that it could go much longer, and you might have a much longer lifespan, or you just don't want to jinx it and talk about it now?
GROTZINGER: Yeah, well, you know, we get that question all the time, and our - my answer to it is the - we promised the sponsor, who is NASA, a two-year mission, and that's what we hope to deliver, and after the clock strikes midnight after the second year, the warranty expires, and all bets are off. We're removed from our obligation, but we hope that this rover will live as long as it can.
The one interesting thing about this is that there's enough of these missions now, and space missions are a little bit like babies, you know, once they're sort of turned on to do their thing, if they last six seconds, they might last six minutes, and then they might last six months, and it's even possible you'd get six years.
So when Spirit and Opportunity, way back when, were in that sort of infant phase, you can see that the mortality rate decreases as the spacecraft gets older. So for us, you know, if we make it to that two-year boundary, we have hope that we'll last, you know, quite a bit longer.
FLATOW: One last question because I'm surprised at the attention, the world attention that this mission got. And NASA certainly did everything it could, from putting the Jumbotron working in Times Square. But I think it eclipses anything I expected. Would you agree?
GROTZINGER: I definitely agree. We - coming into this, those of us that were sort of involved in the higher-level discussions about how to roll out the mission and make it the most attractive to the public, you know, we were really worried that between this being an election year and the Olympics happening coincidentally, we wondered what would happen. And I think all of us are just touched with how much attention we've really gotten.
FLATOW: All right, John Grotzinger, thank you very much. We've run out of time. And good luck to you.
GROTZINGER: Thanks very much for having me.
FLATOW: You're welcome. Dr. Grotzinger is project scientist for the Mars Science Laboratory Mission, aka Curiosity, and professor of geology at Caltech. Transcript provided by NPR, Copyright NPR.