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Digging in the Dirt, Scientists Succeed on Mars

JOE PALCA, host:

This is Talk of the Nation: Science Friday from NPR News, and I'm Joe Palca. Ira Flatow is away. Later in the hour, a look at a tiny, but important marine microorganism, and a peek inside the brains of tune-deaf people. But first, this week, researchers operating the Mars Phoenix Lander managed to get a tiny sample of soil into an onboard oven, filling up the oven.

The oven will be used to bake the soil and analyze the gases that it gives off. Getting the soil into the oven has been a bit of a challenge. Joining me now to talk about it, and what happens next in some of the other projects onboard the Mars Phoenix Lander, is Peter Smith. He's the principal investigator from NASA's Mars Phoenix mission, and he's also a senior research scientist in the Lunar and Planetary Laboratory at the University of Arizona in Tucson. Welcome back to the program, Dr. Smith.

Dr. PETER SMITH (Principal Investigator, NASA's Phoenix Mars Mission): Hello, I can't hear you.

PALCA: Oh, well, that's too bad. Peter Smith is in Arizona. Can you hear me now?

Dr. SMITH: Yeah, that's much better.

PALCA: Okay, good. Well, Peter Smith, this is Joe Palca, and we're on Talk of the Nation: Science Friday. How are you?

Dr. SMITH: I'm great. How are you, Joe?

PALCA: Good. Good. So it's been a couple of weeks since JPL, but I gather, things are moving along, but maybe not as fast as you had hoped.

Dr. SMITH: Well, we got through our characterization phase, which allowed us to put a scoopful of soil onto our first instrument, and lo and behold, it wouldn't go through the screen. And this is not a problem with the instrument, which is functioning perfectly, but Martian soil turns out to be very clumpy and sticky. And isn't it nice that we have just the right instruments there to understand why it is so?

PALCA: Well, actually, I was going to ask you about that. So let's just step back for a second. So the Phoenix landed, it did everything on - everything - it put out its solar cells, and it has stretched out its arms, and it got ready to do all of its experiments, and the main experiment is to scoop up the soil, and this is soil up near the north pole of Mars, which is going to have a mix of ice and dirt.

Dr. SMITH: Right.

PALCA: So it's going to scoop the dirt, and it's going to drop it into these special instruments...

Dr. SMITH: Right.

PALCA: And so it was supposed to sprinkle the dirt down on a sort of a - looked like a sieve with a - that shakes back and forth. Why wasn't the dirt falling into the instrument?

Dr. SMITH: Well, that's the million-dollar question. We've now got a sample of this material inside of our microscope, and we can see that the particles are very small. Much smaller than the size of the openings in our screen. In fact, almost undetectable in size in our microscopes, so they're very tiny particles.

And either it's the mineral that it's made out of, some sort of sticky clay, or its salts that are holding this soil together, so that it has trouble getting through the screen. But the good news is, Joe, that after seven tries during five Martian days, the soil has now gone through the screen, and it's in the oven.

PALCA: I want to invite our listeners to join the conversation. The number is 1-800-989-8255. That's 1-800-989-TALK. And oh, by the way, if you want more information about what we're talking about this hour, go to our website at, where you'll find links and the - both the University of Arizona and the NASA people have put up some fantastic pages that really help you get into this mission.

But my question, Peter Smith, is, OK, so it took seven tries. What made the seventh try better than the first six?

Dr. SMITH: Well, you know, one theory is that the soil dried out. It was now up on the surface of the spacecraft, where it's much warmer than down on the surface, and perhaps there was a little bit of ice in the soil, and over several days, it dried, and as we shook it the seventh time, it started to move.

PALCA: You know, I wish I could have said it much smarter just a few seconds ago, because as I was thinking about this, this morning, and I've been listening to all your press conferences, and we've been talking about this notion that there's ice in the soil, and maybe it would sublime if it just got a little bit warmer.

Dr. SMITH: Right.

PALCA: That's what people think might have happened, it went from a solid to a gas and suddenly the particles were freed up to fall through the sieve.

Dr. SMITH; Well, that's - that makes sense. Otherwise, it's kind of hard to understand why it didn't go through the first time.

PALCA: Yeah, yeah. Got you.

Dr. SMITH: So anyway, the good news for us is scientifically, this is a very unusual soil, not like any of the soils we're told would be on Mars, and that we tested in our lab, because those went right through our sieve and this doesn't. So, we're really curious as to why.

PALCA: Cool. Let's take a call now because we have listeners who are - have their own theories about what happened, so let's go to Andrew in San Francisco. Andrew, welcome to Science Friday.

ANDREW (Caller): Well, thank you, yeah, I was just thinking. I was kind of listening to what you were talking about and such, and also think of reasons why the soil might be sticking together, you said possibly salts or clay, but I was wondering if there's any kind of mineral, or just something that could it magnetically sticking together, possibly even to the screen itself, or just to itself.

Dr. SMITH: Well, that's a good point. It wouldn't stick to the screen, which is a non-magnetic material. But the Martian soil is known to be magnetic, and certainly has a component in it that is magnetic, and we're seeing that in our microscope, which has some magnetic substrates, so we can see which particles sticks and which don't. So that's something we're pursuing and it's a possibility.

PALCA: Andrew, thanks. That was an interesting thought.

Dr. SMITH: All right. Thank you.

PALCA: Sure. Peter Smith, once - now you've got the sample in the oven, and first of all, this oven is how large?

Dr. SMITH: Oh, it's very tiny. It's like a pencil lead, half an inch long. It's about the size of it. And it's tiny because, we're going to heat it up to a thousand degrees Centigrade, which is 1800 Fahrenheit, and if we had a big oven, it would take more power than the spacecraft can produce. So we have to have a small oven.

PALCA: Right. And what happens when - I mean what do you learn as you heat up a sample of soil to this high temperature? What are you looking to see come off of it?

Dr. SMITH: Well, at the lower temperatures, we'll see any ice coming out. You know, the boiling point of water on Mars at, where we're landing, is only 4 degrees above freezing. So, at very low temperatures, we see any of - the ice will be boiled away or evaporated. And then as we heat the higher temperatures, there's other water molecules that combine more tightly to the soils, for instance clay, or some salts can hold water pretty tightly, but we'll hit those temperatures, then we'll know the temperature, and we'll see the water come out of the soil, and that will tell us exactly what type of clay it is, or what type of salt.

And then other materials that can come out, are organic materials, 3 or four hundred Centigrade, they tend to come out. And we'll be able to see an organic spectrum in our mass spectrometer. And then at higher temperatures, you can see carbonates decompose, and carbon dioxide will be released. So there's a whole spectrum of minerals, and salts, and other materials that are formed through the action of liquid water that will decompose at these temperatures.

PALCA: So, this is just - this instrument, TEGA, that you're working on now, that's the heating oven, what other instruments are on board, and when will they start getting their samples?

Dr. SMITH: Well, we have results today from our microscope. We're going to be releasing those images very shortly, and we see at least four different kinds of particles, in the first pictures down from the spacecraft, which came down yesterday, and so there's kind of a complex mixture inside of these soils.

In fact, they even clump at the microscopic level, so they're very unusual materials, or at least, unexpected materials. And - so, we'll be trying to figure out what the four components are that we see in the microscope. We have the ovens, we have the microscope, and our third instrument is a wet-chemistry cell, and this is quite nice, because that, we add water that we brought from earth to the soil, and we mix it up, and we looked for all the salts that go into solution into the water. So, there's a whole range of materials that'll go into solution. And we'll be studying those.

Let's take another call now, and go to Austin in Wichita, Kansas. Austin, welcome to the program

AUSTIN (Caller): Hi. I just had a question. Are you guys going to bring the soil samples back to earth?

PALCA: Hmm. interesting.

Dr. SMITH: Why, we'd sure love to. But we can't. We're - this is a one-way trip.


PALCA: Is that - Peter Smith, is that a plan for a future mission? To bring that sample back?

Dr. SMITH: Yes. And it's been on the books for quite a long time, and it may not happen till somewhere in the 2020s.

PALCA: Ah. Why would you want to bring a sample back? I mean, you've got all these instruments on the Lander, what do you gain by having the material back on earth?

Dr. SMITH: Well, the instruments on the Earth are much more powerful than the ones we have on Mars, and there's no end of different types of analysis that you can do, and we've certainly proven that, using lunar soils, where you can look down at the very tiniest grains, and get a complete analysis of each grain. We're not able to do that with remote instruments.

PALCA: Mm. I got it. Now, what about - I mean, you're what? Two weeks or yeah - just over - just under two weeks right, into this mission?

Dr. SMITH: Right.

FLATOW: How long - how are you doing in terms of accomplishing milestones? You were, I think optimally hoping to be finished with the check out phase in one week, and now we're coming up on two. Do you feel like you're getting - things are moving at their proper speed?

Dr. SMITH: Actually, I do. Actually we got out of our characterization phase after about 12 days. We had a couple of hiccups with our communication through the orbiters. But you know, it takes a little while to get this complex system all running smoothly, and even though we've tested and tested, there's still some little bumps on the road that you have to get over.

And we think we've gotten over all that, first, the soil was stickier and clumpier than we thought it would be, and we're having trouble getting it through our screen. We had a couple of start-up problems with our instruments. Those have all been resolved. And so now, we, for the first time in 32 years, have soil inside of instruments on Mars. And we feel that we're making rapid progress.

PALCA: That's exciting. I'm just thinking now of going forward for the next soil sample. Are you going to have to do this same trick of waiting several days for the soil to bake? Or do you have ideas about how to get it through?

Dr. SMITH: That's a good question. We don't want to go through that again. So we've developed a new method during this time of sprinkling, and we can tilt the scoop, and we can - we have a little vibrator on it, and we can just kind of sprinkle out some material, and that should hit the screen particle by particle, and go through much easier, that just dumping a load on it.

PALCA: And just out of curiosity, what time of day is it on Mars now? Because we started out, we were sort of - Earth and Mars we're sorted at the same time and now, they probably got out of sink a bit.

Dr. SMITH: Yeah, they certainly have. It's 40 minutes change every day. Let's see, the last I looked, it was 19:00, what would that be? That's seven o'clock?

PALCA: Seven o'clock at night. Yeah. So, that's later in the day. Well, I know you guys have got a lot to do. And I appreciate you're taking the time to talk with us about this today. We'll be following the mission through the end, I hope. And I hope it's a long ways off.

Dr. SMITH: Oh, stay with us, know. We're going layer by layer from the surface down to whatever is beneath the - at least ice. We think we found ice, and we're - we ought to prove that. And it's the question of what's preserved in that ice, that makes this mission so interesting.

PALCA: Well, we'll come back and find out. Thanks very much, Peter Smith.

Dr. SMITH: Hey, you're very welcome.

PALCA: Peter Smith is the principal investigator for Nar - Mars - NASA's Mars Phoenix Mission and is also a senior research scientist at the University of Arizona in Tucson. We're going to take a short break. When we come back from the surface of the red planet, we'll be going to the blue ocean. Stay with us.

JOE PALCA: This is Talk of the Nation, from NPR News. Transcript provided by NPR, Copyright NPR.