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IRA FLATOW, host:

You're listening to Talk of the Nation: Science Friday. I'm Ira Flatow. In the next part of the program, we're going to talk about something very, very mysterious, and it's about Mars; it's about the plumes of methane on Mars. And maybe you were able to watch like I did yesterday; NASA has teleconferences that reporters can login to and watch NASA scientists talk about new research that they're reporting on. Sometimes, their research gets reported not just by NASA, but in journals at the same time. And in this case, it was reported in the journal Science. And what they were talking about was something really, really mysterious, and this was the discovery of a plume of methane gas that rose from the surface of Mars back in early 2003. And the question that is - was on the minds, and is still on the minds, of all of the NASA folks who studied this is, where do you get a plume of methane gas coming from on Mars?

Now, we know it's possible that methane could be made in couple of different ways, and scientists were on there to talk about the different ways that methane can be made. We know if you know here on - if you're on Earth, you know how methane is made, could become - come from swamp gas, right? It could be made by biological methods that are made here on Earth. Bacteria, it comes stored from old bacteria, sometimes stored underground. When you, you know, you drill for oil or gas, you get methane belts. You got - or it could be made from other kinds of ways on Mars. It didn't have to come from, you know, from the biological or maybe the geological side of it. Maybe there was water. We know there's water. It leaked underground and hit a hot spot, and the water, you know, were released - the methane came belching out of the side.

Well, we're going to discuss that with Michael Mumma. He is a senior planetary scientist and director of the Goddard Center for Astrobiology at NASA's Goddard Space Flight Center in Greenbelt. He joined us from a studio there. Welcome to Science Friday, Dr. Mumma.

Dr. MICHAEL MUMMA (Director, Goddard Center for Astrobiology, and Senior Scientist, Solar System Exploration Division, Goddard Space Flight Center, NASA): Oh, thanks very much, Ira. It's a pleasure to be with you.

FLATOW: Is this as mysterious to you as it is to us here, as it is a wonderfully mysterious discovery?

Dr. MUMMA: It is, actually. You know, we're all puzzling about what could be generating this methane and how it can be released from the surface of Mars.

FLATOW: Now, do you have one theory that you prefer over the other? Let's talk about the two theories. I mentioned that there could be the biological side like there is here on Earth, right?

Dr. MUMMA: That's correct. Here, we have both microbes that make methane - we call them methanogens - and some that actually use the methane as food, called methanotrophs. And so, it could be biology that's responsible for the methane on Mars.

FLATOW: Or it could be geology. How could geology make methane?

Dr. MUMMA: Actually, there are two different ways in which methane is made by geology on Earth. The first, of course, is in the influence from volcanoes; gas emerging during volcanic eruptions can, in fact, release methane in very small amounts, but also releases far more sulfur dioxide. We'll come back to that in a moment. On the other hand, there's a much cooler process, lower temperature, in which warm rock in the deep Earth is reacting with water and CO2 and converting the form of rock called olivine into a different mineral called serpentine and releasing methane in the process. So, either one of these is a potential candidate for the release on Mars.

FLATOW: Mm-hmm. 1-800-989-8255 is our phone number, talking with Michael Mumma of NASA, talking about this mysterious plume. Does the plume shoot out of something, like a big plume?

Dr. MUMMA: Well, most people would think of a plume as a, for example, a geyser...

FLATOW: Right.

Dr. MUMMA: Or a plume of water shooting out of a water hose. But this is not at all what we mean by a plume. The plume we're referring to is actually the - a plume more like a huge cloud of pollution that would waft in from a city over the countryside or even from a different country into our country. This plume on Mars has a dimension that's measured in thousands of kilometers, almost the size of half the United States, if you like.

FLATOW: Wow.

Dr. MUMMA: Yeah. And at the center of this plume, we identified three specific regions where areas of release where the methane apparently is emerging from the subsurface of Mars.

FLATOW: Wow. Now, one of the biggest mysteries you also mentioned at this news conference was if you have so much methane coming out, why isn't there so much left, right? It's coming out at such huge amounts. Where's it going?

Dr. MUMMA: Well, that's right. In fact, we observed these major releases in March - January to March of 2003, and yet, just barely over one Mars years later, we found that at the equinox season - this was about six months later on Mars, essentially - about half of methane had vanished. It was not anywhere present in the atmosphere. And so, we infer that the lifetime of methane after release from subsurface is very short. It could be as short as only one Earth year in destroying about half of it. And this is actually quite puzzling, led to some brand new ideas.

FLATOW: And so, where is it going? What kind of ideas were they?

Dr. MUMMA: Well, there's a team at the University of Michigan led by Professor Sushil Atreya. And they came up with a novel idea that the dust in Mars' atmosphere may actually be charging up to high levels, kind of like a static electricity would develop as you walk across the carpet in a dry room. And then when you reach for a piece of metal connected to the ground, you're going to get a shock. Well, in a similar way, these dust particles in the atmosphere of Mars might develop literal electric discharges from their edges in trying to discharge this high-voltage potential. And that discharge can actually cause the creation of a new superoxidant, a molecule which can actually combine with methane and destroy it. The prime candidate is a molecule called peroxide, which, of course, I would say at least half of your listeners would know of that because it's the same chemical that's used to bleach hair.

FLATOW: Hydrogen peroxide.

Dr. MUMMA: You've got it.

FLATOW: Yeah.

Dr. MUMMA: You bet.

FLATOW: So, is there any evidence that tilts your thinking or a lack of evidence of something that tilts your thinking one way or the other, either biological or geological?

Dr. MUMMA: Well, there is. In fact, I mentioned earlier that volcanoes produce a lot more sulfur dioxide than they do methane. And so, when we compare the abundance of sulfur dioxide on Mars relative to methane, we find that, indeed, SO2 is very low in abundance compared with what belches out from terrestrial volcanoes. So, this would tend to argue against active volcanism, at least to the type that is active on Earth, as being responsible for this gas on Mars. But of course, we don't know whether serpentinization, this other process I mentioned, the low-temperature geochemical process, could be occurring. We don't know for sure whether it is or not. And we, of course, we don't really know that we have biology at work either. So, we need to make a number of careful tests and diagnostic measurements in order to further constrain these possibilities.

FLATOW: Can you do that from so far away?

Dr. MUMMA: Well, you can, in fact. We are using several of the world's largest telescopes, some on Mauna Kea in Hawaii at an altitude of almost three miles, 14,000 feet. And beginning this August, we'll be using a telescope in the Southern Hemisphere in Chile, one of the very large new European telescopes. With our European colleagues, we'll be investigating the methane from that site. So, what we can do with these is we can actually search for not only the methane, but also other gases that are released along with it, such as ethane or propane. If it's released from a standard hydrocarbon deposit on Earth, for example, you might see multiple kinds of this natural gas being released. We can test for that. And on the other hand, we can look for gases that would be reached only by biology, if they're similar to Earth, things like nitrogen, dinitrogen oxide, N2O, and some other things such as H2S, hydrogen sulfide, and so forth. So, these are the kinds of tests we can do from Earth.

There are some that we cannot do from Earth very well. We would like to measure both the isotopic ratios in hydrogen atoms and also in carbon atoms, because we know that life on Earth dislikes heavy carbon, for example. It tends to combine with light carbon, and so the methane formed from biogenesis on Earth is usually depleted in carbon-13, a heavier isotope. So, by comparing that on Mars, we can begin to gain some understanding as to whether biology could be at work or not.

FLATOW: And so, we need to send another rover there or something.

Dr. MUMMA: Well, in fact, there's one on the way. It hasn't been launched yet, but the - it will be launch in 2011. It's called the Mars Science Laboratory at the moment. And it has instruments onboard that are tailored at making such measurements of rare isotopes and methane and other potential biomarker gases.

FLATOW: So, should - would the new mantra then be "follow the methane" instead of "follow the water"?

(Soundbite of laughter)

FLATOW: I heard that saying expressed.

Dr. MUMMA: Well, that's right. I mean, follow the carbon was one for awhile, and follow the water, and perhaps follow the methane is the right strategy. But we think that the way to think of this is that this discovery represents the - really the first evidence that Mars is an active planet, not just something that - a planet that underwent development billions of years ago, and we can see this now in a geological record, but a planet that's currently active. And so, this opens a new window, a new dimension, if you like, into this exciting place. But it also means we need to adjust our thinking about how we go about exploiting that new window, that new line of evidence. It clearly is going to imply that we want to eventually put probes down at the places where the most interesting release is occurring.

So, we have a lot of work to do in order to identify those spots. But clearly, one of the areas we've looked at already and identified as a region of active release is a canyon called Nili Fossae. Fancy words, it's kind of like a continent name on Earth. But it's a place where earlier observations of minerals had found things that could form in liquid water, particularly clay minerals called phyllosilicates, and also carbonate minerals like limestone, which could be either from life forms or not. It can form it in several ways. The key point is they're made in liquid water, and now we see methane emerging from that same region in large abundance. So, this becomes a prime region for exploration, and as you may know, Ira, it was one of the five finalists for the landing site for the Mars Science Lab that's supposed to be launched in 2011.

FLATOW: Is it moving way up now?

(Soundbite of laughter)

Dr. MUMMA: Well, as a matter of fact, it's back in the running. It was actually eliminated from the running in December because the site is a little bit challenging to reach. It's a little too high for the parachute to slow the (unintelligible) rockets to slowly lander properly. And it's also a relatively rough site in terms of its surface terrain. But now, with this new discovery, it's - we have a two-year gap here between the launch that was expected in 2009 but now has slipped to 2011. We have another two years to rethink this, and I believe that this will be in fact, reexamined to see if, indeed, those other issues can be overcome.

FLATOW: So, you have two serendipitous things that happened. One is that the launch slipped. So, you can maybe redirect, right?

Dr. MUMMA: Well, that's right.

FLATOW: Where, you know, you would have gone by now.

Dr. MUMMA: Maybe someone out there is looking out for us.

(Soundbite of laughter)

FLATOW: And you have this new source of methane that combines with the other clues that you have.

Dr. MUMMA: Well, that's right, and you know, the right way is not to jump to a conclusion about which of these possibilities is actually producing methane. but rather to follow each possibility, identify what new tests we need to make in order to see whether that one's correct or not, and then go down the path a little further in each direction until we see which one is emerging.

FLATOW: Mm-hmm.

Dr. MUMMA: We may find, Ira, that there are some vents on Mars that are actually, mainly biologically driven, and perhaps there are other ones that are actually driven by geochemistry. It could be that we have some of each.

FLATOW: Mm-hmm. Talking with Michael Mumma of NASA Goddard Space Flight Center in Greenbelt on Science Friday from NPR News. So, it sounds like a bonanza happening just when the budgets are all being cut.

Dr. MUMMA: Well, you know, it's funny. I made a comment in yesterday's press conference that was broadcast worldwide, as you know. And I commented, now, look, folks, without regard to budgets...

(Soundbite of laughter)

Dr. MUMMA: And without regards to politics and other planned missions, here's what I think we should do if I were just thinking of this as a scientific prospective.

FLATOW: Yeah, and...

Dr. MUMMA: I think we should, in fact, go forward and map Mars over at least two Mars years, do the entire surface daily or weekly, monthly, try to identify all of the sites that are active, which ones repeat from year to year, which do not, which ones are likely biochemical and geological or biological in origin, and this way, build a data - I won't call it a data cube, because that has only three dimensions; I'll call it data polygon - use database which basically will tell us, let us look at this in detail, tell us the various chemistries of these gases coming out.

FLATOW: Let me ask you one question, because we're running out of time. If this is a geological emission, would it be from old - if it were a life form, would it be a living form or a would it be left over from an old life form that's just escaping to the surface now?

Dr. MUMMA: Well, that is a possibility. We can't actually identify the age of the life form or the process that is producing the methane at the present time. That's going to require a lot more work and much more in situ sampling and so on before we can answer that question.

FLATOW: But there could be life living below the surface that's close enough to the heat to get enough heat to survive because we have salty regions like that here on Earth.

Dr. MUMMA: Well, in fact, there are, in fact, many analogues on Earth. There is a life form living deep below the surface in South Africa, which does not live on energy derived from the sun, but rather lives on energy derived from radiation in the rock, the nuclear radiation through the decay of nuclide which destroys local water in fissures there, and then, provides hydrogen atoms, which combined to make an energy source for the microbe that lives in that region. That microbe is -does not produce methane, but it does produce hydrogen sulfide. And we have other microbes elsewhere that produced methane, which can - or some that eat methane for food. So, it turns out these critters are highly adaptable, and we can well imagine that there was a methanogen and a methanotroph living under the deep permafrost of Mars in regions that had been isolated in the surface for many, many millions of years, even billions.

FLATOW: So, one might be making it, and one might be eating it.

Dr. MUMMA: That's quite right. Yes, indeed.

FLATOW: And that would explain getting rid of the methane gas.

Dr. MUMMA: We think the methane destruction is not related to eating the methane.

FLATOW: I see.

Dr. MUMMA: Because what we see has escaped into the atmosphere and we think, actually, the destruction is related to this superoxidant material that's produced by normal processes, and probably the methane that escapes in the atmosphere is reacting with that material.

FLATOW: Well, Mars continues to surprise us. Too bad we can't get those little rovers over there.

(Soundbite of laughter)

Dr. MUMMA: We'd love to.

FLATOW: But we'll have to wait for the big one...

Dr. MUMMA: Absolutely.

FLATOW: To be repositioned. Thank you, Dr. Mumma, for taking time to be with us.

Dr. MUMMA: Ira, it's a great pleasure. Thank you.

FLATOW: You're welcome. Michael Mumma is senior planetary scientist and director of the Goddard Center for Astrobiology at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Short break. When we come back, we're going to talk about the history of pheromones, pheromones. Stay with us. We'll be right back.

(Soundbite of music)

FLATOW: I'm Ira Flatow. This is Science Friday from NPR News.

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