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Fri October 12, 2012
Curiosity Rover Gets the 'Scoop' on Mars
Originally published on Fri October 12, 2012 1:45 pm
IRA FLATOW, HOST:
This is SCIENCE FRIDAY. I'm Ira Flatow. The Mars rover Curiosity scooped its first sample of Martian soil last weekend. The mission controllers plan to use it to clean out an instrument on the end of the rover's robotic arm that filters and sorts samples for analysis. But work was halted when a small, strange, shiny object was spotted on the ground between Curiosity and the robotic arm. Where did it come from? Could it be something that came off the rover itself? The rover also made a surprising rock find. And here to provide us with update on the mission is Michael Watkins. He's Curiosity's mission manager at NASA's JPL laboratory in Pasadena. Welcome to SCIENCE FRIDAY.
MICHAEL WATKINS: Good afternoon. Glad to be here.
FLATOW: Thank you. What - you ever figure out - you guys noticed a small bright object on the ground. It's clearly visible in the photos that you sent back to us. Did you figure out what it was?
WATKINS: Partially. There was actually a couple of them.
WATKINS: And we're - we looked around as we see a few little bits and pieces like this one. The very first day, we - it looked really shiny to us, looked kind of silver. And we thought...
WATKINS: ...did we just shake a screw off of ourselves or something?
WATKINS: You know, like, did we just undo one of our bolts, you know? Because we did the scoop and we do a little vibration to settle the material in the scoop, kind of, you know, like if you're flour sifting or something, you kind of want to shake it down a little bit. And so we actually had a little vibration motor and we started vibing. And then we looked at the scoop and it looks great. And then we saw this little silver thing, and we just want to make sure we didn't accidentally back out a screw or do some other crazy thing.
And as soon as we took a close look at it, we could see it looked more really like a piece of plastic, more like, kind of a little bit like a shiny bit of plastic. And it kind of just caught the sun at the right angle that made it look kind of silvery. It actually looks more like a little piece of plastic.
FLATOW: So you discovered plastic on Mars?
WATKINS: Exactly. And almost certainly our own litter. So, you know, we do - it looks like a little bit of cable wrapping or cable tie-down. You know, we have lots of cables on the rover and we had lots of them, you know, in the parts of the spacecraft that we threw away, like on the heat shield and the descent stage and all that. And so the best guess right now is, you know, we cut a lot of cables when we start separating the spacecraft to, you know, to touchdown, throw away the heat shield. It's probably little bits and pieces of that stuff that kind of, you know, fluttered down and is around us still.
There might have been a little bit that fell on the deck. You know, if you drive your car through a, you know, through a confetti, you know, through a ticker tape parade in the way to your drive home and then you look around your driveway and there's still little bits and pieces you carried with you. So that looks like our best guess right now.
FLATOW: Yeah. So you're not - there's no concern that something, you know, like we - we home-brewmakers leave little extra parts and screws and bolts, thing, lying around.
WATKINS: Yeah, that's right. That was certainly our concern, like why is this left over? But, no, it's almost certainly not a fastener like that. So at this time, it looks like there's pretty low concern.
FLATOW: And the soil. You shoveled up your first bit of soil. Tell us what that was like.
WATKINS: Yes. Well, so it's the first time that the rover - that the scoop, the arm and the sort of Swiss Army knife of tools at the end of the arm actually touched Martian soil. And so we want to make sure that we could control the arm accurately enough, that we could scoop down and not jam the scoop into the ground and also not, you know, sort of take a swing and miss the ground. But the arm actually was really good. We got a perfect scoop. The scientists helped us pick a very boring sandpit. You know, it looks exactly like any random bit of Mars sand over the whole planet, and scooped it up just perfectly in the scoop. You guys saw the picture.
And then we went ahead and ingested that through the, you know, through this path that we will eventually drop samples into the instrument. And used - sort of shook it. So we'd like to joke that we kind of sandblast that clean by vibing the Martian sand in that, you know, through those little chambers. And it kind of blasts the wall just like sandblasting it to make it clean. And then we throw it out. And we do that a couple of more times to make sure we're clean in there.
FLATOW: Is that like to get off any grease or things that are left from production or when you loaded it?
WATKINS: Yeah, pretty much, and not just production. So, you know, we try as hard as we can to clean everything up and get it clean as we can. The problem is there's the air on the Earth, and the air on the Earth just has lots of organics stuff in it, and it will just kind of adhere to the wall. So if you just - it's just open in the air for, you know, any amount of time, you're going to have this very faint residue that could contain some organic materials. And so the analysis was if you scrub that really well with this Martian material, we can easily get down clean enough.
FLATOW: It reminds me when you go camping. You know, when you got a pan you want to clean out, you put some dirt in it and you rock it around in there and cleans out all the debris, and now you got a clean pan.
FLATOW: I can see what you...
WATKINS: Good point.
FLATOW: ...see what you guys were doing a week beforehand. 1-800-989-8255. Talking with Michael Watkins, Curiosity mission manager at JPL. Now, tell us about this, you zapped a strange-looking, pyramid-shaped rock that you had not expected to see or you hadn't seen any of it on Mars before.
WATKINS: Well, so I think that, you know, they hadn't seen exactly this particular rock. That rock, you know, it's called Jake Matijevic, right? And we named it after one of our lead engineers. You probably - you may know the story. He was a instrumental guy on the very first rover we put, Mars Pathfinder, and then Spirit and Opportunity and on this mission. He unfortunately just passed away shortly after landing. So we named this first big rock that we sampled after Jake.
And what we really wanted was, you know, sometimes there's a fine line between engineering and science, right? So the scientist helped us pick a rock that they thought was very uniform in structure, very fine-grained, so that when we looked at with two of our instruments, one that's on the end of the arm, the Alpha particle X-ray spectrometer, or APXS, that tells us what the rock's made of, and we could compare that to blasting it with our ChemCam device, right? A ChemCam hits it - hits the rock with a laser, makes a little plasma, a little spark and looks - sort of looks at the color of that spark and determines what the rock is made of.
And when they compare those two measurements, kind of cross-calibrate these instruments - so they picked a rock. They thought it would be kind of a basalt. They thought it would be something that they could easily get the same results between the two instruments. It turns out that the rock is similar to the things you see on volcanic islands in - on the Earth, looks like a kind of igneous rock that often has volcanic origin on the Earth. It also turns out to have a little bit of sort of differential structure in the rock so that the exact little tiny spot that ChemCam laser hit is similar but not exactly the same as kind of the larger average spot that the APXS instrument examined. And that's kind of interesting, and the scientists are looking - are still looking at that.
FLATOW: Why was that surprising to find that kind of rock there?
WATKINS: Well, I'm not sure that it was - well, so two things - let me say two things about it. First, of course, is that, you know, there are many scientists, hundreds of specialists in Mars science and geology and Earth geology looking at that, and I'm not one of them, so I will give my layman - semi-layman's impression. But I think the first thing to say is, you know, any one rock is pretty hard to interpret what's going on and its origin.
And so the real advantage of geologists on the Earth is, you know, they go out and they do field geology, and they look all around. They don't just have one rock in their laboratory from which they can really learn where it came from. They want to go see the rock, where it formed, look at all the rocks around it, you know, look at the whole history of the area to, you know, to get a better understanding. And I think they just - we're just not there in terms of understanding exactly why this rock is there.
FLATOW: Mm-hmm. And - but it is similar to a kind of rock you would find on Earth?
WATKINS: Yes, it is fairly similar. And the scientists were discussing that, have been discussing that in the last few days. We don't know whether it formed in exactly the same way that those rocks formed on the Earth, though. That's the part we don't quite know yet. You know, is it just a volcanic rock or is there another way it could have formed on Mars differently from the Earth?
FLATOW: So are we still in the testing phase of the Curiosity? Are we in full, you know, roving mode?
WATKINS: So we're in and out of the testing phase. So the way we kind of think of it as the rover can do, you know, 20 different things and we've commissioned, you know, like 18 of them. And so those are in full mode. But there's a couple more that we're still making sure we know how to do. And those two are still kind of important, right? That's the scooping and the drilling into rocks and getting them into our chemistry labs.
So we're roving. We're, you know, we've driven a couple hundred meters away from the landing site. We've used virtually all of the instruments, and they're in use every day. What we want to do now, as we talk about the scoop, make sure we know how to use the arm correctly, make sure we know how to get that sample through all the little chambers and everything, in the portioner and all that, and then drop it off accurately into our - open the doors of our instrument and drop it off accurately in there. And then make sure that those instruments accurately process that to determine the chemistry and the composition and the mineralogy of those instruments.
So that phase, we're still going to be in that phase of checking out those instruments for a couple of weeks here. And we think the first end-to-end thing where we get results out of the analytical instruments will probably be maybe two weeks from now or so.
FLATOW: That's why you're in this boring rock piece of sand there, just like...
WATKINS: Exactly right. So we're using kind of a boring thing just because it's a good way to test out those instruments. And when they're tested out, then of course we go look for the most interesting stuff for all the remaining instruments.
FLATOW: Let's go to the phones. Gary in Sacramento, hi. Welcome to SCIENCE FRIDAY.
GARY: Hi. Good morning. Good topic. Assuming that the shiny objects aren't soda can or beer can pop tops of some alien variety, how are you going to go about differentiating between whatever your spectrum are or spectra are of your results for your sample there to eliminate the possibility that it might be something else that was either on the mother ship or on the rover that got trapped into your scoop by accident?
WATKINS: Yeah, so that's a good question. Of course, you know, we don't think that these, of course, are, you know, are in our scoop. We can look at our scoop and see what we have in there and see what we had before. But, you know, your general question is a good one, which is how do you know anytime you make a measurement whether you're measuring residual Earth stuff or Mars stuff. And the way we do that is really two ways. First, we run the instruments just on - just as they are exactly as they've landed without putting Mars into them. So both instruments, our X-ray diffraction instrument that we call CheMin and our gas chromatograph mass spectrometer, kind of a CSI kind of instrument that we call SAM - those guys actually run their blank cups and see what they're reading out and that tells them what the background level of cleanliness really was. And so then, when they put this - the Mars in, they can know, OK, but I already tested the blank and I know what the background was.
We also actually carry - sealed up in a container - a control sample, that we know exactly what it's made of. And we can actually drill into that and put that through the instrument. And we have several of those blanks and check again throughout the mission what - are we really reading what we think we're reading with this known sample? And if we're not, let's subtract that extra error out from what we measure on Mars.
FLATOW: Here's a tweet from J.R., who says: Have you learned or made any corrections to prevent Curiosity from getting stuck like Spirit in the sand?
WATKINS: Yes, we have. That's a good question. It's something that concerns us all the time. It concerned us certainly on Spirit and Opportunity. One thing to remember is that those missions tended to have more and more trouble as they got older, and one of the wheel motors failed. So it didn't have quite as much torque available as we do. But the other thing we do is we all the time now check for slipping. So we run this visual odometry code all the time. Our flight computer is a little bit faster, and we're able to check for slip more or less constantly so that we don't bury ourselves in. As soon as we start to slip too much, we immediately will stop and back out of that area. So we hope to have our motors - all six wheels driving for a long time, and we also will do the slip check pretty much all the time that we're driving.
FLATOW: Let's say - what - let me just say that this is SCIENCE FRIDAY from NPR. I'm Ira Flatow, talking about the Mars rover with Michael Watkins. What's the RPM of those wheels, just to get an idea how fast it moves comparative to what we have in our cars here.
WATKINS: Well, it moves much, much more slowly, and the reason is really - it's not so much driven by how fast we can turn the wheels. It's because we actually turn the wheels a little bit, and we drive a meter, and then we look around us, and we check for slip. And we also make a new stereo map of the terrain in front of us, and we make sure that it's safe to keep driving there. So on the ground, we do this planning and we say, gee, it sure looks safe if we tell the rover to drive over here. But we want the rover to also check autonomously.
So what it does is it stops, takes these two pictures, thinks about it, makes a stereo map and then starts to roll a little bit more. So if you were to actually watch the rover driving, a lot of the time it would not be driving. A lot of times when it's driving, it drives a little bit, stop, and is thinking, and then driving some more. And that's really what gets us the net drive speed. So the most we can ever get probably is maybe 100, maybe a little more than 100 meters, a football field or so in a day. But if you're in difficult terrain, we might only drive, you know, a few meters per day.
FLATOW: Yeah. Reminds me of someone trying to learn how to drive a stick shift.
WATKINS: Yeah, exactly.
FLATOW: A little - buckle, go a little.
FLATOW: Yeah. Let's go to the phones, to Bobby in Keizer, Oregon. Hi, Bobby.
BOBBY: Yeah, hi. Long-time listener, first-time caller. I was wondering, is there anything that you might discover that you're not allowed to tell us about, like the government restricts you from telling us about discovering certain things, like, say you've discovered alien bones or something? I mean, is there anything you're restricted from telling us about?
WATKINS: No, we are not restricted. In fact, we send all the data out almost as soon as we get it, and it's available on the Web here, the JPL websites, NASA websites. We put it out pretty much as soon as we get it. And it's not - it has happened in the past that someone else has noticed things in images before we did. There's lot of, you know, legions of fans out there taking a look at it. So, no, we don't - we pretty much put everything out as quickly as we can.
In the case of the science instruments, they sometimes want to make sure that they get a scientifically valid answer, they don't accidentally, you know, say that they've discovered something when the test wasn't right. So the scientists, you know, go through a review process to make sure that it's right. But for the images and engineering data, we put all that out right away.
FLATOW: Was it you guys that looked at the shiny object first, or did it come in from the Web someplace? Somebody noticed it looking at the photos.
WATKINS: I think in that case, we found it - I think we found it first. But there have been other times when interesting stuff has been found by folks out there on the Web.
FLATOW: Yeah. And so where is the next destination for you guys to take it?
WATKINS: So we're heading, in the short term - so you know, the long term - I think you guys know about this. The long term is we want to get to the base of this mountain, this Sharp Mountain because it can - we can read the history of Mars and go back to this oldest Mars terrain when it was wetter. But that's a few kilometers away. So it'll take us a while to get there. About 100 meters or so away from us, there is the - a meeting place of a couple of different geologic units, a couple of different places that look a little different. There's an area that looks like it had a lot of craters in it. There's another area that looks like it's really fractured and kind of badlands kind of stuff.
And then there's - we're in this kind of hummocky, kind of little rolling knobs of material. And all three of those kind of meet at this location that the scientists have dubbed Glenelg, G-L-E-N-E-L-G, and they want to drive up to there and take a look at that. What's the difference between those geologic units? Why are they different? And is there anything interesting about the place that they meet? And so after we get done in our sand pit here, the sand pit is called Rocknest. After we get done with that and test out our instruments, we're going to drive over to Glenelg and probably actually drill using our rotary percussion, our little jackhammer, into the outcrop there.
FLATOW: Well, have a good trip and good luck to you and don't drive like my brother. So...
WATKINS: Thanks very much. I hope to talk to you again.
FLATOW: Take care. Michael Watkins is a Curiosity mission manager at NASA's Jet Propulsion Laboratory in Pasadena, California. Transcript provided by NPR, Copyright NPR.