Sifting Martian Soil and Dreaming of Future Expeditions

Soil collected last year by the Mars rover Curiosity may contain two percent water, researchers report. Laurie Leshin of Rensselaer Polytechnic Institute describes what else the rover is finding in the soil, and what that information might mean for future expeditions to Mars.

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IRA FLATOW, HOST:

Speaking of research that's going on, we continue to follow new developments on Mars. It's not news anymore that Mars has water. Scientists have seen the ice caps. They've seen the marks of erosion. But writing in the journal Science, researchers report that the soil itself on Mars has water in it, about the same as you'd find in desert on Earth, but it's enough to quench your thirst.

Joining me now to talk about it is Laurie Leshin. She's one of the authors of that paper. She is dean of the School of Science at Rensselaer Polytechnic in Troy. Welcome to New York. Welcome to SCIENCE FRIDAY. You are in New York.

LAURIE LESHIN: Yes, I am. Thanks.

FLATOW: You're in the state of New York.

LESHIN: Thank you for having me.

FLATOW: So what is new about the soil here? Is it the amount of water that's in the soil?

LESHIN: That we really quantified very well, the amount of water. We did a pretty amazing experiment. We scooped up some dirt beneath our wheels near Curiosity's landing site and we sieved it a little bit. And then we dropped it about a half a baby aspirin's worth at a time into our cups which went into an oven and heated it up three times hotter than your oven at home. And we scanned as we were heating up and detected lots of different things coming off the swell, but water was the most abundant at about 2 percent.

FLATOW: Most abundant.

LESHIN: Um-hum.

FLATOW: How much water would - how much soil would you have to do to make a cupful of water?

LESHIN: Yeah, so I did this quick back-of-the-envelope calculation on it. If you took about a cubic food of dirt on the surface of Mars and you heated it up to just a few hundred degrees, you could get out a couple of bottles of water, a couple of pints of water.

FLATOW: Really?

LESHIN: Yep.

FLATOW: Just with a cubic food of dirt.

LESHIN: Yep.

FLATOW: That's optimistic, isn't it?

LESHIN: Well, it's kind of what the data are telling us. So in that sense it's glad.

FLATOW: Well, I mean, if you were going to Mars and you needed some water...

LESHIN: That's right.

FLATOW: ...you could - is just any dirt there? Does it have to be a certain kind? Where is water linked into the dirt?

LESHIN: Right. So this is an interesting thing about Mars' dirt. It's one of the reasons that it's so interesting to study it on Mars, even though most of us don't think about the dirt beneath our feet very much on earth. On Mars we've had a lot of experience doing sort of more basic kinds of bulk chemical analysis of dirt everywhere we've gone where we have a little sensor that we just stick out on the end of an arm and we analyze the dirt.

And it kind of looks like the dirt is the same everywhere you go on Mars. So by studying it in detail in one place, like we have with Curiosity, we're kind of learning about the whole planet. So it's my expectation that you should find a small amount of water chemically bound in the dirt like we did pretty much anywhere you go on Mars.

FLATOW: Wow. There was another paper published that found disappointingly, a lack of methane in Martian samples. Because wasn't there some research before that had shown plumes of methane on Mars?

LESHIN: So interestingly this is the same, you know, workhorse instrument in the belly of the rover called Sam that made - that analyzed the - found the water in the dirt that also can occasionally suck in atmosphere, so suck in gas from the Martian atmosphere and analyze that. And one of the things it can look for is methane very sensitively. And it's true that our colleagues used that instrument.

And that paper was published a week before ours in Science showing that they - you know, down to, you know, a per billion or less or so don't see methane in the atmosphere. And it's a very sensitive measurement. And the fact that it's being done on the surface of Mars it means, I think, that it's very accurate. The previous measurements had been telescopic measurements based on earth, kind of looking at Mars from afar. We're sitting there right in the middle of Mars' atmosphere and analyzing this.

FLATOW: One last question. How is the shutdown affecting the rover team?

LESHIN: Right now we're continuing to operate. You know, the Mars rover is managed by the Jet Propulsion Lab, which is a contractor facility run by Caltech. And so most of the folks that work on the rover are not government employees. Those that are we're backfilling those roles. But we're going to have to assess on a week-by-week basis to see if we're still able to keep operating. But for now we're drive, drive, driving every day.

FLATOW: But that could change if this continues.

LESHIN: It could absolutely. We'll assess week by week.

FLATOW: All right. Thank you for taking time to talk with us today.

LESHIN: Yeah, my pleasure.

FLATOW: Laurie Leshin is dean of the School of Science at Rensselaer Polytechnic University. That's up there in Choi, New York, and co-author of a paper in Science about what's in the Martian soil. We're going to take a break. When we come back we're going to talk about encryption. Is it possible encrypt your files anymore? Has NSA got all the codes to break in? How to do it, what to expect? Our number 1-800-989-8255. 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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