'Curiosity' On Mars
JOE PALCA, host: This is SCIENCE FRIDAY. I'm Joe Palca, filling in for Ira Flatow. Well, if you liked the Pathfinder rover, the little bitty Pathfinder, and then you liked even more the slightly bigger Spirit and Opportunity rovers, well, you're in for a treat because we're heading back to Mars with the Mars Science Laboratory rover. It's also known as Curiosity and it's heading to Mars later this year. If all goes to plan all goes according to plan, Curiosity will reach the Gale crater of Mars by 2012.
It's designed to make a soft landing, lowered to the surface by a rocket-powered sky crane. And this would be some kind of crazy landing to see because if you check out the simulations that NASA has put up on the website it's just wild the way this thing comes down, or is supposed to come down. We hope it comes down.
Joining me now to talk about Curiosity will be one of once it lands will be up on top of it, on top of everything once it lands, is the chief scientist for the mission, John Grotzinger. He is a professor of geology in the division of Geological and Planetary Sciences at CalTech, the California Institute of Technology. Thanks for joining me today, John.
JOHN GROTZINGER: Thanks for having me.
PALCA: You're very welcome. So, Curiosity. First of all, now bounce down this time? No airbags?
GROTZINGER: Yeah, that's right. Curiosity weighs a lot more than Spirit and Opportunity did. In fact, it weighs literally a ton and because of that extra weight we can't use the landing air bag system anymore. So JPL had to design what's called an active propulsion system that has rocket engines that allow the spacecraft to hover above the surface of Mars and then reel the rover down on a series of cables until it touches the ground.
And then once it touches the ground, the cables are cut, the hovering spacecraft goes off and crashes on the side, and the rover is pretty much ready to go.
PALCA: I know. It's really, I just ever since I saw that, it just struck me as the greatest I don't want to say Rube Goldberg because I'm sure it's not that complicated, but it certainly is a wild way of coming down.
Oh, by the way, if you have questions you would like to ask John Grotzinger give us a call at 800-989-8255. That's 800-989-TALK.
So this is a bigger rover. I mean, if the others were coffee table size, this is about the size of a compact car. I presume that means there's a lot of extra instruments on board.
GROTZINGER: That's right. We've got instruments, 10 of them, 10 science instruments, that were built by nine principal investigators and the principal investigators are responsible for using the instruments once it's on the surface of Mars. And what we've got, then, is a way to use all of these instruments synergistically to get at a more set of advanced questions than what we've been asking in the past.
PALCA: So, OK. In the past, as I've said a number of times when I've reported on this, we're looking for water. We're searching for signs of water. It's always water, water, water, water. Well, now we think we're pretty sure there was water. What are we looking for now?
GROTZINGER: So now we're still using water as one of the leading indicators of where to go but now in addition to that we're also able to see before we land minerals that formed in the presence of water. And so when we see minerals we also get an indication of what the chemistry of the rocks are.
And so with some sense of both the mineralogy and the chemistry of the rocks and all of the sort of morphologic features, like ancient river channels, that tell us about water, we can now begin to get a sense of what the environment was like. That if life had evolved on Mars what would the environments have been like that microorganisms would've lived in? And so we call this the search for habitable environments.
PALCA: And is there - you're not going to actually be able to detect a microorganism, are you? Or will you see something crawling along or will you see signs that they were once there, if they were there at all?
GROTZINGER: That's right. MSL is not a life detection mission. We have no ability to see extant life if it were there and so we are focused instead on trying to answer the question if the geological and environmental conditions were right, is this the kind of environment that life might've existed in as microbes.
And so the goal is to really to characterize that environment to try to understand how they would've interacted with it in the past.
PALCA: Now, this mission was supposed to launch two years ago but things were a little backed up and you had to delay two years. What's the delay meant and is it causing you any problems? I mean, there's still lots to do before you get to Mars, I understand.
GROTZINGER: That's right. We did have a delay. We were supposed to have launched in 2009 and when you take a mission to Mars, you get an opportunity for a few weeks every two years. So when we get - when we fell behind on building the spacecraft we had to wait two years.
But that turned out to be a blessing in disguise because this mission is the most complicated rover that's ever been put onto the surface of another planet. And that extra two years has bought us some time to think about how we're going to use these instruments, to do additional testing of the instruments, and all around to ensure that we're going to have a better science investigation as a team.
PALCA: But you're going to make this launch.
GROTZINGER: We are going to make this and we're going to launch, hopefully, on Thanksgiving Day in November.
PALCA: Have you actually talked to the staff who are saying couldn't you pick another day? Because...
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PALCA: ...Thanksgiving Day some people like to spend with their families.
GROTZINGER: Right. Well, for MSL we make it possible for all the families to join us down at Cape Canaveral and I know that my family is excited to come down. So we'll be able to spend that time together and everybody's part of the family.
PALCA: OK. Well, I'll see if I can talk my mother into coming down, as well. Let's take a call now and go to Isaiah in Washington, D.C. Welcome to SCIENCE FRIDAY, Isaiah.
ISAIAH: Hi. Thanks for having me on.
PALCA: You bet. What's your question?
ISAIAH: I'm wondering what kind of technologies on the Mars rover will be adapted for the average consumer in the near future?
PALCA: Oh, interesting. The spin off kind of question. Thanks, Isaiah. Well, John Grotzinger, you have - I mean, are there life detectors or mineral detectors that you're going to be using on Earth from this mission?
GROTZINGER: Well, as a matter of fact, we've already had one spin off and it is a mineral detector. It uses a process called X-ray diffraction and it's the standard technique by which you look at crystalline substances here on Earth.
And the group that has built this, Dave Blake at NASA Ames and Philippe Sarrazin, have been able to compartmentalize this in a really miniaturized format and now it turns out they have other uses as well.
For example, most drugs in the solid form are in a crystalline state and so they've had some early business already in looking for things that might've been falsified, drugs that are used for anti-malarial drugs in other countries.
PALCA: Wow. That's pretty interesting. I was sort of being facetious. I didn't think there would be anything but there you go. You have something already. Let's take another call and go to Ed in Long Island, New York. Ed, welcome to SCIENCE FRIDAY. You're on the air.
ED: Hi. Hi, how you doing, Ira? Oh. Tremendous fan. I'm curious about the altitude the rover is going to be lowered down from from the rocket.
PALCA: Ah. So this is the crane that extends the thing that goes down a tether and then it flies along at the bottom of the tether. When does that happen?
GROTZINGER: Right. So that is at the very end of our entry, descent, and landing sequence and basically the spacecraft decelerates through the Martian atmosphere. The heat shield is ejected. A new spacecraft that we call the descent stage emerges, and it descends under powered rockets until it's very close to the surface, a few hundred feet.
PALCA: Aren't you leaving out the parachutes?
GROTZINGER: Well, yes. All this happens while the parachute is deployed. So we go from supersonic to subsonic speeds. And then we get down very close to the surface and now this separate spacecraft called the descent stage is flying on its own with the rover attached to its belly. And then when it's a few hundred feet above the surface, it then reels the rover down on three cable, and then it gently descends at about a meter per second after that. And then when the rover feel - when it feels the bottom, because its wheels are touching, then the cables are cut and it's off on its own on the ground.
PALCA: I just love it. But how do you test something like this? You're not building a simulation for it to run on Earth, are you, or a backup on to try it out on earth?
GROTZINGER: Yeah. Something as complicated as this with the difference between the atmosphere of Mars and Earth and also the difference in gravity between Mars and Earth, it really isn't possible to test it rigorously by building one and flying around here on Earth. So instead, JPL uses the same approach that other space missions use, which is to study it using numerical simulation. So they have big computers that are programmed to simulate the way that the spacecraft will behave, and they test it that way.
PALCA: All right. You know, one thing I've been wondering is NASA's very good about finding photo ops. Is there any way that we'll be able to see live pictures as this thing comes down? Maybe a camera on the rover, or a camera on the descent part of the spacecraft?
GROTZINGER: Yeah. It'll be a great movie. The cameras - and we have 17 on them, on MSL - five of them are dedicated to science, and one of them is attached to the bottom of the rover. It's built by Malin Space Science Systems. And that camera, as soon as the heat shield falls away from the descending spacecraft that's attached to the parachute, a camera will turn on, and it's full color, HD resolution, five frames per second. And it will make a movie of the whole time that we are descending down to the ground, including touchdown.
PALCA: And does that come back right away, or do we have to wait a few days for that to come back?
GROTZINGER: Yeah. We'll have to be patient because, as you might guess, that's going to be a big data volume, but we'll try to get it down as quickly as possible. Initially, there will probably be a thumbnail version of the movie and then, as time goes by, based on how much data we get sent down each day, we should be able to put it all together and release it on a website for the public to see.
PALCA: Wow. So what do you think? I mean, it was pretty nerve-wracking for the Spirit and Opportunity to come down, and they both made it. I know you're not going to say it's not going to make it, but are you worried at all?
GROTZINGER: Well, we're always worried. You know, Mars is a difficult place to reach, and, you know, NASA and JPL have been very successful in the past But, you know, there are times when things don't work out. So we're always mindful of that. And I think that there will be a lot of suspense with this landing system because if it's successful, it will then pave the way for future landing events that will be even more substantial than what MSL's going to do.
PALCA: Okay. Well, we'll keep our fingers crossed. Thanks very much for joining us today.
GROTZINGER: Thanks for having me.
PALCA: John Grotzinger is Professor of Geology in the Division of Geological and Planetary Sciences at the California Institute of Technology, otherwise known as Cal Tech in Pasadena, and he's the principal investigator - or a principal - the principal investigator for the Mars Curiosity Probe that's landing at the end of - later this year.
Stay with us. We're going to talk about an asteroid that's just taking us for a ride, or maybe we're taking it for a ride. Don't go away.
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PALCA: This is SCIENCE FRIDAY, from NPR.
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