Planetary Radio: Space Exploration, Astronomy and Science - Signs of Life? Discovery of Martian Methane Plumes

Episode Date: February 23, 2009

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Is something alive up there? Methane on Mars, this week on Planetary Radio. Hi everyone, welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. Something is creating natural gas on Mars. Is that something alive? Or is this a geological process? No one would like the answer more than Michael Mumma, leader of the team that discovered and localized methane plumes

on the red planet. He's our guest on today's show. Bill Nye is back with thoughts about Hayabusa, the little Japanese asteroid probe. Emily Lakdawalla also returns to answer a question of yours about Venus. And way down the line, Bruce Betts and I will give antimatter its due as we find out which of you is the winner of another space trivia contest and explore the night sky. Were you looking forward to the next space shuttle liftoff?

Well, keep looking. NASA has announced that Discovery's mission to the International Space Station must be delayed again as they continue to work on a problem with some critical fuel valves. No new launch date had been named as we finished this week's show. Speaking of NASA, the agency has just signed a deal with the European Space Agency for joint exploration of Jupiter and its moon Europa. The mission won't happen until about 2020. It'll be followed by a similar shot at Saturn and Titan. Details are at planetary.org.

Here's Bill. Hey, Bill Nye, the planetary guy here, vice president of the Planetary Society. And this week, another remarkable thing happened fantastically far from Earth. The Hayabusa spacecraft, which is a Japanese spacecraft, launched in 2003. And it's had all kinds of trouble. It's had fuel leaks, said it's spinning. They stopped the leak. Another leak happened. It was spinning the other way. They gave it a gravity assist with the Earth. They sent it past the moon. Anyway, it went out to this asteroid, Itokawa, and it tapped

it. And it's presumed that it knocked up some asteroidal material and scooped it up in this kooky little basket. Well, here's the thing, my friends. It's on the way back. So this mission has been underway for six years. And it's got another year to go before it parachutes onto the continent of Australia. Now, here's the thing. It's been using an ion drive, like in science fiction movies. It uses xenon, the same gas that makes the bright blue light in a flash system on a camera. for hours and hours and weeks and weeks and months and months and years and years,

31,000 hours. And this thing is finally on the way back. And pretty soon, we may have our first piece of an asteroid. Once again, my friends, we will learn something about our place in the universe. We will learn a little bit more about where the Earth came from, where these asteroids came from. Why didn't they accrete into a big planet, why did we have the dumb luck to be on a planet with liquid water, all these fabulous questions can be chipped away at, pun intended, with the Hayabusa spacecraft.

And Hayabusa means falcon in Japanese. And here's to a safe, soaring home. I gotta fly. Bill Nye the Planetary Guy. By the way, if you caught Bill's great TV show, it's called Stuff Happens, and it runs on the Planet Green Network. I love it.

You probably heard the announcement a few weeks ago, or maybe you read the story at planetary.org. A team of planetary scientists has found three separate plumes of methane emanating from the surface of Mars. It's one more tantalizing bit of data that is consistent with biological activity underway right now on the planet, or at least not too far in the past. But there are other possible sources that don't depend on the presence of life. Michael Mumma led the team that found the plumes. He directs the Goddard Center for Astrobiology and is a senior scientist at the NASA Goddard Space Flight Center in Greenbelt, Maryland. We got him on the phone a couple of days ago for a conversation about this discovery.

Mike, that was a very exciting announcement made by your team a while back, these methane plumes on Mars, something, though, that you folks have been working on for years. Matt, we actually started this investigation back in 1989 using an instrument at the Kitt Peak National Observatory in Tucson, Arizona. And that instrument wasn't sensitive enough to make the detections. We had to wait another 10 years until the instrumentation did become available and we were able to resume. I guess this is the best possible evidence that there's still a heck of a lot we can learn about distant places without actually having to send a probe there. Of course, you did use some of the most powerful instruments on this planet. Well, we did. In fact, we used the Keck telescope, Keck 2 in particular, one of the two twin 10-meter

telescopes in Mauna Kea. But most of the observing was done with the NASA Infrared Telescope in Mauna Kea, which is a relatively small one these days, only 3 meters in diameter. But nevertheless, these have very powerful instruments connected to them, and the combination has really made them much larger than they would have seemed as little as 10 years ago because of these very powerful instruments that essentially increase the aperture of the telescope by a large amount. How were you able to localize this search to certain sections of the planet? Well, what we do is we place the entrance aperture of the spectrometer. The aperture is a long slit, essentially an opening between two parallel razor blades, if you like.

We normally orient this north-south along the planet's meridian, and then the slit width defines the location of light that's sampled on the planet itself. The slit width defines the location of light that's sampled on the planet itself. So we see regions ranging all the way from the northern limb of the planet, the most extreme portion we can look at, through the equatorial zone as one proceeds downward along the slit, and then finally exits at the south limb. And at the same time, the light is diffracted and it's re-imaged onto a two-dimensional detector array in the focal plane of the instrument. And this gives us the ability to measure a spectrum

at each discrete little aperture along that slit. So, for example, when we look at Mars and it's approximately 7 arc seconds in diameter, we would obtain about 35 individually measured spectra at points along the slit from north to south. or the amount of methane, carbon dioxide, or water, whichever molecule we're looking at, at these different positions in latitude going from north to south on the planet. And, of course, if the planet is rotating and we take slit spectra at sequential times, then we're basically sampling different areas of the surface as they move under the slit. And so in this way, we can then build up a two-dimensional map,

and one in longitude and one in latitude, by combining the temporal series with the series along the slit itself. And so in this way, we can map the planet over a period of perhaps five or six hours, we might map as much as 60 or 70 degrees of longitude. Obviously, you discovered this activity, and it was localized. And we will link to both your website at Goddard and to an excellent article by my colleague, Amir Alexander, that talks more in depth about how this took place. Alexander that talks a little more in depth about how this took place. Were you surprised that you were able to find not just the presence of methane, but these so-called plumes? The big surprise was finding that there were discrete regions that appear to be releasing methane into the planet's atmosphere, and at particular seasons. We had thought that we would be able to detect methane itself,

but we did not expect to see these active regions, and in particular the plumes. And by the way, for your listeners, I should say that when we speak of a plume, we are not talking about something like a small geyser. We're talking about a pollution plume such as you might see over a large area, downwind from a large city or from a forest fire, which of course we don't have on Mars. But similarly, the gases released from these active regions spread out over a large region and create this large enhancement that we call a plume. So that in itself was very surprising.

We did not expect to see this. And yet there it is, as can be seen in some of the maps that you were able to put out that show in parts per billion the presence of this gas. And you said there were seasonal variations. There are. In fact, we saw these intense areas of release in mid-summer in the north of Mars. This was terrestrial time. It was March of 2003.

And then we looked again at a slightly later season on Mars, and we found that most of the methane had disappeared. That is to say, it had been destroyed in the meantime. It was a total time that was about one and a half Mars years. So the season then was spring in the northern hemisphere, what we'd call the beginning of spring or vernal equinox here on Earth. So between mid-summer and then the following vernalinox, or early spring, about half of the methane had been destroyed. And this was, again, another surprise. Until that time, we had thought that the lifetime of methane on Mars

would be on the order of 300 years, which even so is extremely short and would indicate that if you see methane, it had to be released relatively recently, could not be a remnant from the early phase of Mars history. But our lifetime is about 100 times shorter than that, and this implies that there is another process which is destroying methane very efficiently. That's Michael Mumma, leader of the team that has discovered three plumes of methane gas on Mars. Our conversation will continue after a break. This is Planetary Radio.

Hey, hey, Bill Nye the Science Guy here. I hope you're enjoying Planetary Radio. We put a lot of work into this show and all our other great Planetary Society projects. I've been a member since the disco era. Now I'm the Society's Vice President. And you may well ask, why do we go to all this trouble? Simple. We believe in the P, B,

and J. The passion, beauty, and joy of space exploration. You probably do too, or you wouldn't be listening. Of course, you can do more than just listen. You can become part of the action, helping us fly solar sails, discover new planets, and search for extraterrestrial intelligence and life elsewhere in the universe.

Here's how to find out more. You can learn more about the Planetary Society at our website, planetary.org slash radio, or by calling 1-800-9-WORLDS. Planetary Radio listeners who aren't yet members can join and receive a Planetary Radio t-shirt. Members receive the internationally acclaimed Planetary Report magazine. That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. Is there life on Mars? We still don't know,

but the discovery of methane plumes adds one more piece to the puzzle. Michael Mumma directs the Astrobiology Center at NASA Goddard. He led the team that used Earth-based telescopes to pinpoint the three sources of this natural gas. Anything special about the locales in which these plumes are located? Well, there are special things about these locales. In particular, one of them occurs over a region called Neely Fossi. There's a major impact basin just north of the equator on Mars called the Isidis Basin. And this basin has a fracture ring around it. We often see these in other impact basins elsewhere in the solar system.

And indeed, a portion of this fracture ring has collapsed at one place to form a depressed canyon called the Graben. And in this Graben, orbiting spacecraft have discovered minerals that clearly indicate they formed in liquid water. So this appears to be a place where serpentine and various carbonates have formed eons ago when liquid water was present. And of course, with liquid water, one can imagine that there were other things going on as well. But the big surprise for us was that one of our active regions is centered directly over

this graben or this deep cleft called Nili Fossi. Another one was really interesting. This is a shield volcano, which is somewhat younger than the Nili Fossi formation. It's a shield volcano called Syrtis Major. This is about 1,200 kilometers in diameter at the base. That's about 600 miles, maybe 700 miles for those who think in the English system. But in any case, to our great surprise, we thought at first the plume might be centered

over the caldera where gases might still be leaking out from deep below. But indeed, it was not centered there. It was centered over the southeast quadrant. So that sent us back to the scientific literature to scurry around and find out what had been learned or inferred about this region of the volcano. And we ran across a paper by scientists from Brown University, which indicated that this particular quadrant of the volcano

was very unusual because it seemed to show evidence of extensive collapse of the subsurface. And this gave rise to surface cracks that were unusual and so forth. So this was an indicator that there were, in fact, massive fractures in this quadrant, distinguishing it from the other quadrants and perhaps giving conduits for methane to leak out from below. The third region, one called Terra Sabi, was actually a region that shows unusual impact craters that have ejecta flow.

This is material ejected from the crater itself at impact. But instead of just being kind of looking like a shatter blanket of rocks, this looks like something slurry or thick, almost liquidus-like structure material flowed outwards and ran down the slopes and formed these very soft-edged, so-called lobate deposits. Various scientists have speculated, or not speculation, have thought these were related to the ejection of an ice-laden material from the crater

that then caused a slurry and enabled this material to flow down the slope in a very kind of thick and viscous way. this material to flow downslope in a very kind of thick and viscous way. So the net information here is that we see methane issuing forth from regions that were once rich in water ice and perhaps other hydrated minerals of that sort. And this, of course, is very interesting and very surprising. We haven't gotten yet to the question that has intrigued so many people since this story came out and put you on a lot of front pages. What's generating this?

Is it bio or geo? Well, that, of course, is the $64 question. And the simple answer is that we must follow each of those possibilities and devise tests that could, in fact, clarify which or if both are, in fact, contributing. We really can't identify or even suggest that we've discovered biology. Nothing could be produced by geochemistry. This does happen on Earth. On the other hand, we have other examples on Earth of deep biospheres

where biota have lived for eons out of touch with photosynthesis. Beneath the deep gold mines in South Africa, there is a community that has been dated anywhere from 20 million to 100 million years in age. And that community basically lives on hydrogen that has been liberated from water trapped in the fractures in the rock. And the water is actually being destroyed by natural radioactivity. And so this forms the ultimate energy source which these microbes use. So what we can do and what we're planning to do is knowing what kinds of chemicals such as higher order hydrocarbons or isotopic fractions and so on are produced by both biochemistry or by the abiotic means, you can then go and search for those and attempt to address this question

of whether we see biology at work or geochemistry. But either way, it's a tremendously exciting opportunity because it gives us a window into Mars as an active planet in a way that we never had before. Are you providing any advice to the folks who are trying to decide now where the Mars Science Laboratory should set down? Well, we gave the Project Science Steering Group a briefing back in October in advance of our publication to let them know that this was a region of particular interest.

You may know that Nili Fosai was, in fact, one of the five finalists in the landing site selection process. And so we felt this was very important and relevant information. Indeed, at about the same time, scientists from Brown had made a discovery of carbonates in the same region. So they also briefed the team. We think it's important now that we have two years' time given to us in the delay of MSL. It could be fortuitous because we can now ask the project team to reconsider their landing strategies, and perhaps in the most favorable case we might be able to consider Neal-E-Fonsi again.

Mike, we are out of time. Congratulations again on this extremely exciting discovery, and best of luck over the next two years as we prepare for the arrival of the Mars Science Laboratory, hopefully dropping it right into one of these regions where it can hunt around for that source of this natural gas on Mars. Matt, thanks so much for giving me a chance to talk to your audience. I hope they found this exciting as we have. Dr. Michael Mumma is Director of the Goddard Center for Astrobiology,

Senior Scientist of the Solar System Exploration Division at Goddard Space Flight Center. We'll continue to follow that research both on the Planetary Society website and right here on Planetary Radio, where we are going to return with this week's edition of What's Up? And Dr. Bruce Betts, right after we hear from Emily. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, Why does Venus rotate so slowly?

The formation of planets was a violent process. The solar system started out as a dusty nebula, where small bodies nucleated and gathered more mass through gravitational attraction. Toward the end of the solar system's formation, there were many more bodies whizzing around than there are now, and enormous impacts were actually commonplace and unavoidable. The moon's origin is thought to have come from the impact of a Mars-sized body with the proto-Earth, and a giant impact is one possible explanation for the extreme tilt of Uranus. So it's not hard to imagine that two proto-planets

could have collided at such an angle that the primordial rotation of the proto-Venus was largely cancelled out or even reversed by the impact. What's much harder to explain, actually, is how Venus could have experienced such a large collision and wound up with absolutely no moons to show for it. According to computer simulations, most large collisions spray ejecta into orbit around the planet, which should coalesce into a moon. And if the moon is orbiting in the same direction that the planet is rotating, tidal effect should cause the moon to move farther from its planet over time as our own moon has done. Simulations suggest that in order for Venus to have suffered large

collisions, which must have happened in order for it to have formed in the first place, it should also have had a moon. So there must have been another late giant impact that acted to reverse the rotation and cause its moon or moons to wind up moving closer to the planet over time and eventually crash into the planet, leaving no trace of their existence. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Well, to the tune of the faint tick-tock of the universe, we are joined once again by Dr. Bruce Betts,

the Director of Projects for the Planetary Society. He's on the Skype connection for this week's edition of What's Up? Welcome back. Thank you very much. Yes, time keeps on slipping, slipping, slipping. Is that your atomic clock in the background yes yes it's an atomic clock designed uh in the late 1800s because i can hear the cc madams going back and forth back and forth i thought it was just me i thought i was losing it thank you thank you tell us about the night sky. Venus, evening sky,

getting lower, but still really easy to check out over in the west. After sunset, it's the extremely bright star-like object. Whole planet party going on in the pre-dawn, but only if you've got a nice clear view to the east, in which case you can see Jupiter, which isn't too hard. It's really, really bright. Below it is Mercury, looking not as bright, but still like a bright star. And then Mars, looking like an even fainter reddish star. Mars will keep getting higher as time goes on. Mercury, we're going to lose pretty soon. It's going to dive back down, and Jupiter will get easier. Let's go on to this week in space history, 40 years ago, the successful launch of Mariner 6. Mariner 6, part of three successful flybys of Mars, 4, 6, and 7,

and all of them showing us, by chance, the heavily cratered parts of Mars, making us thinking it was boring, and really just a bunch of craters. But all that changed with Mariner 9 a few years later. Random space fact. Yeah, Skype just doesn't do it justice. Yeah. Binary star systems, of course. Star systems consisting of two stars orbiting around their center of mass,

each a companion star of the other. Roughly half the stars in our galaxy are binary star systems or multiple star systems. We thought it was more than half, and now recent research seems to indicate that it's probably a little less than half. But in any case, an awful lot of binary stars out there to go along with all the fabulous single star systems like our own. Trivia contest, we asked you, what is the antimatter equivalent of an electron? And how much energy do they release when the two of them come together? How'd we do, Matt? Everyone knew that the counterpart to the electron is the positron. Some people did say the anti-electron, but that's just not as sexy. What did throw some people is the energy released. Some people settled for just saying, well, equals MC squared. And, you know, we said thank you for sharing, but that's times, what, 511,000 electron volts or just over 1 million electron volts, 1.022 million electron volts.

Indeed. Totally. Well, Josh Glazer is the guy whose name came up on random.org this time. Josh Glazer listens to us in Japan. And Josh, I'm so glad he won because he's one of those who gave us much, much more. Bruce, a whole bunch of these guys have way too much time on their hands. They actually derived it. They didn't just look it up. And not only did Josh derive it, but he was joined by a few other people who wanted us to know that if I really wanted to run my cell phone off of this reaction, I'd need a few more positron-electron pairs annihilating. In fact, he figured it out

as 6.10 times 10 to the 11th, which sounds like a lot, but then he came up with the mass that would be necessary to run my cell phone for one second, 1.11 times 10 to the minus 15 grams of matter and antimatter. And now I just- You could probably carry that around, okay. I probably could, yeah. You know, maybe some shielding would make it a little bit tougher in my pocket. Now, is that just to run it for a specific amount of time? That'd be one second.

Oh, okay. Oh, so you'll need more than that. We also had Brent Pantalone. He also derived it. And he mentioned that sometimes positronium is formed. That's a cool word. Positronium! Positronium, which is where an electron is fooled by a positron into thinking that the positron is a proton and forms a little atom

called positronium. So we learned from this that positrons are devious. Yeah, they're not only dangerous, they're devious. Exactly. Keep an eye out, everyone. Anyway, we're going to send Josh a year in space calendar and a rewards card from Oceanside Photo and Telescope. Then let's go on to the next trivia. In the English language, besides Earth, what other planet in our solar system is not named after a Roman god? Not named after a Roman god. English language, besides Earth, planet. Go to planetary.org slash radio. Find out how to enter and compete

for a fabulous prize. And guess what you've got until Monday, March 2nd at 2 p.m. Pacific time to get us that answer. We're out of time. All right, everybody, go out there, look up in the night sky and think about your favorite video game. Thank you. Good night.

He's Bruce Betts, the Director of Projects for the Planetary Society. You'll find him in this world and the virtual ones here on What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California. Have a great week. Thank you.