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IRA FLATOW, host:

Next stop, the mysteries of Mercury and Mars. Time for our solar system quiz. What planet has a volcano larger than a state of Delaware and a crater in it shaped like a kidney? Wait, wait, don't tell you, of course, it's Mercury, you knew that. Just one of the surprising findings about the M&M planets, Mars and Mercury, making news this week. Earlier this year, the Messenger Spacecraft flew by the planet Mercury, getting a closer look at our solar system's smallest planet, sending back fascinating photographs and data about that very hot body. And joining me to talk more about it is Ralph McNutt Jr., he is a project scientist for the Messenger Mission. He's based at the applied physics laboratory at John Hopkins University in Laurel, Maryland. Welcome back to Science Friday, Dr. McNutt.

Dr. RALPH MCNUTT JR. (Project Scientist, John Hopkins University, Laurel, Maryland): Well, it's good. Good to be here.

FLATOW: You're welcome. Mars of course, continues to make news, rather the - actually, I should say, the robotics spacecraft digging up the planet there do. Also joining us now is a sort of Science Friday's regular, Peter Smith is a principal investigator for the Phoenix Mission, whose scoop and now fork - we'll have to talk about the fork - has been feasting on Martian soil. Welcome back to Science Friday, Dr. Smith.

Dr. PETER SMITH (Principal Investigator, Phoenix Mission): Oh, thank you very much.

FLATOW: Let me, let's talk about Mercury first. Some really interesting findings there.

Dr. MCNUTT: Exactly, it's been a long time coming too.

FLATOW: Tell us what the most surprising thing is so far?

Dr. MCNUTT: Well, you know, I think that the - I think that the most surprising thing actually has been seeing how dynamic a system that Mercury is. I mean, we've been able to take a look at what's going on with the interaction of the magnetic field with stuff that's boiling off the surface and forming a very, very thin atmosphere, and a plasma environment. But that's sort of from my background, the other exciting thing of course, is that we've been able to see parts of the planet that have literally never been seen before by human eyes.

FLATOW: And one of the things - one of the things you noticed is, that the planet is shrinking.

Dr. MCNUTT: Well, that's right. You know, we had some evidence about the shrinkage of the planet back in its early days for the Mariner 10 mission over 30 years ago. But what we've been able to see with Messenger is that these what are called lobate scarps - cliffs - are actually more dominant on the surface of the planet than we thought. The system of those are much larger and looks like the shrinkage was bigger than we thought we had from Mariner 10.

FLATOW: Well, that's interesting, we got to take a short break gentlemen. We'll come back and talk lots more about Mercury and about Mars, and about the missions that are going on there. Stay with us, 1-800-989-8255. 1-800-989-TALK. Also, if you're in Second Life, go to Science Friday Island there, and you can ask a questions as avatars. So, stay with us, we'll be right back after this short break.

(Soundbite of music)

FLATOW: You're listening to Talk of The Nation, Science Friday. I'm Ira Flatow. We're talking this hour about the Mars and Mercury with Ralph McNutt, Project Scientist for the Messenger Mission, he's taking great photographs of Mercury. And Peter Smith, principal investigator for the Mars Phoenix Mission. Our number, 1-800-989-8255. We were talking about finding that Mercury seems to be shrinking more than you thought.

Dr. MCNUTT: Well, that's exactly right. And again, it gets back to trying to understand what happened in the early part of the formation of the solar system, and that's one of the big things that the Messenger Spacecraft is out to help us learn about.

FLATOW: You also, if for so - you're taking much better pictures than you did last time, over 30 years ago. If we were close by on that spacecraft, looking down or being on the surface, what would be the main features we'd see on the surface?

Dr. MCNUTT: Well, you'd see craters. There's a lot of craters, but you also see craters that are filled in with lava flows, and you'll also see, what certainly looked to be volcanoes. That was one of the big controversies that was left over from the Mariner 10 Mission about whether that there were volcanoes and volcanic actions that had flooded some of the craters back at the beginning of the planet. And that's something we've been able to confirm with the new look we've had by using Messenger.

FLATOW: And how about the inside of the planet? Have you learned anything new about its core?

Dr. MCNUTT: Well, we're starting to learn that it's a very dynamic thing, too. You know, with the Mariner 10 Mission, we discovered a magnetic field, and Messenger have shown that it is indeed still there as expected, but also very highly influenced by the solar wind. And we know that with that magnetic field that there is a liquid core, and we're going to be getting some better handle on that with the rest of the Messenger Mission as well. So in Mercury is very dynamic place.

FLATOW: Wow.

Dr. MCNUTT: With a lot of things still going on.

FLATOW: Not just this hot rocks sitting out there.

Dr. MCNUTT: Not just a hot rock.

FLATOW: And the Messenger Space probe. How long will it be going for? And what will it doing?

Dr. MCNUTT: Well, we've got another, we're using protocol reverse gravity assist to gradually slow us down on inner solar system. We actually have another fly by on the sixth of October of this year. We'll see another 30 percent of the planet that's never been seen before from a spacecraft. And then, we'll have a follow up fly by in the 29th of September of 2009. And then we actually go into orbit in March of 2011, and we'll be operating in Mercury over, the first that's ever happened for at least one Earth year.

FLATOW: Any chance you might find in this hot dry place any evidence of water?

Dr. MCNUTT: Well, as a matter of fact, we may actually, already have found evidence of water. Again, this is in looking at the data of what's called the FIPS Instrument. It's part of the pay load, we're seeing what appeared to be ions of water. And some of that at least presumably is coming from the planet.

FLATOW: That would have to be made in the shade as they say.

Dr. MCNUTT: Well, exactly, and actually there are this polar deposits, that are in permanently shadowed craters up near the poles, and those have been seen image by radar from the earth. And for all the world, they look like that they may be composed of water ice. And we may be seeing some evidence of that, and that certainly one of these stay tuned kind of stories that we're going to be looking at - I mean, more and more details as the mission goes on.

FLATOW: Well, Peter Smith, should we be moving one of your probes to Mercury?

Dr. SMITH: Oh. Any time now. Yeah.

(Soundbite of laughing)

FLATOW: Looking for water, because you've been pretty successful. Now, it looks like you found some very good evidence of water on Mars, right?

Dr. SMITH: Well, we certainly have. My gosh, we landed on a place where it looks for all the world, like dust and rock, as far as you can see. But if you take your robotic arm and scrape two inches off of the surface. It's an ice sheet, we're basically on an ice skating rink on the northern planes of Mars.

FLATOW: How are you so sure of that?

Dr. SMITH: Well, we've actually scraped a little chunk of this very hard material off and watch it sublimate. In other words, vaporize from solid to vapor. And we don't have another hypothesis as to what other material would do this at this temperatures. But to make absolutely certain Ira, we're actually going to get a scoopful of this very hard icy - what we think is icy material. Put it in one of our instruments and do a mass spectrometer of it, to make sure we've got mass 18 which is H2O. And then we are particularly interested in the impurities that are in this ice. And that - give us any clues about climate history on Mars and perhaps, habitabilities. This is a place life could live.

FLATOW: And you also got, what I've - would describe as sort of a fork now, sticking in to the ground?

Dr. SMITH: Yes, we do have fork , it has four tines. We take the fork and place it in to the soil and it tell us a lot of the properties of the soil. It's conductivity for thermal and electrical transmission. And the temperatures, and my gosh, if there's any even mono-layers of water that are possible to go liquid, from ice to liquid. It's very sensitive for that transition.

FLATOW: And you also have a very, very sensitive microscope that you're using?

Dr. SMITH: We sure do. And in fact, tonight, we get our first pictures with the Atomic Force microscope which, believe it or not, has a resolution of a hundred nanometers, tenth of a micron. So, that's going to be very exciting that it turns out a lot of the soil particles are very, very small and beneath the resolution limit of our optical microscope which can only see four microns.

FLATOW: What can you tell about, you know, looking at such a small or having such a great magnification for a soil particle?

Dr. SMITH: Well, it's really about the history of the soil. I mean, obviously soil starts out as some of volcanic emission and some lava, and then it breaks down bit by bit into smaller and smaller pieces. And there's - if you can see the shapes and the textures of these grains, you can try and learn their history, how they get so small.

FLATOW: Wow, 1-800-989-8255. Let's go to a Second Life for Lore Gaudio says, what made Mercury shrink? Good question.

Dr. MCNUTT: It's been cooling off.

FLATOW: And so, it's like a pie in the oven.

Dr. MCNUTT: Yeah, that's exactly right.

FLATOW: The crust do shrinks that.

Dr. MCNUTT: So, what we think what happened was the internal part of the planet actually shrunk a little bit more than the crust did. And so, as the result, he actually see this evidence of this overlaps in the crust on the surface.

FLATOW: Mm hmm. Let's go to the phones. Phil in Burke, South Dakota. Hi, Phil.

PHIL (Caller): Yeah, hi, there.

FLATOW: Hi, there.

PHIL: I have a question for Dr. McNutt about Mercury. I thought, I read that there was a lower abundance of iron on the surface found by Messenger. And how do you, if it's true, how you connect that with Mercury seeming to have a great density. And a large iron core and in addition to that, you talked about how it got to be so dense in the first place.

Dr. MCNUTT: Well, you know, actually, to sort of reverse the order. Trying to understand how it got so dense has to do with the formation of the planet. And that's one of the things that we're going after with Messenger to try to understand exactly how the planet was put together early on in the history of the solar system. And some evidence for that has to do with exactly what we see in terms of both the minerals and the elements in the upper part of the crust. And you're absolutely right, what we're seeing so far with the minimal - what we've gotten from the fly-by is that we seem to not have that much iron oxide.

That is consistent with one of the hypotheses, and basically the irons there because the iron all sunk to the bottom as it were, the gravity well. And leaving the - leaving the surface actually somewhat depleted in iron. And so that it fits in with some of the scenarios, and we're still working through that. We've just only begun to really scrape the surface with this first fly-by, and it's going to actually take the orbital phase to really be able to map the mineralogy of the surface to be absolutely certain. But so far, that's the picture that's emerging, and there is a way of sort of putting a consistent story together.

FLATOW: That's one of the interesting things about Mercury and Mars. Mercury being so much smaller than Mars but having more dense iron. Isn't the gravity about the same?

Dr. MCNUTT: That's right, that's one of these really strange things. If you look at the numbers, it turns out that the gravity that you'd feel your weight on the surface of Mercury, is almost exactly what you'd feel walking around on the surface of Mars.

FLATOW: Let me ask you Peter Smith, talking about Mars. You've got a whole sort of Swiss Army knife of tools there, to get down to that surface.

Dr. SMITH: Yes, we do. We want to make sure that we could interact with the very cold ice. Its temperature is minus 90 centigrade which is probably about as cold as any ice you could ever find in Antarctica in the winter. And when ice gets that cold, it's gets harder, it's almost the hardness of the sidewalks. So, we brought some tools with us to be sure that we could get samples of this very hard material and that's what we're actually doing this week. This is kind of the prime science phase of our mission. And we're interacting with the ice now, we're getting kind of scoopfuls of icy soil, and putting it in our instruments. And I think over the next few weeks, we'll have some very interesting discoveries to report.

FLATOW: We'll let say, you know, you confirm that it's ice, it's real water. Is it mission accomplished?

Dr. SMITH: No, no, no. We're following up on the discovery by Odyssey scientists in 2002 that there was a lot of ice in these Northern Plains, and the first thing was we weren't too sure that when we landed, we would actually be able to reach out and grab it.

FLATOW: Mm hmm.

Dr. SMITH: But that was an important part of our mission is to make sure that we could actually interact with the ice, and now we know we can. And so, now it's all about what that ice has to tell us about climate change and the chances for life on Mars.

FLATOW: 1-800-989-8255. You know, we've always heard about Mercury being such a hot inhospitable place. Ralph, how do you work in a Mercury day there and what keeps you from overheating the instruments?

Dr. MCNUTT: Oh, well you have to be real careful about how you design them thermally. And actually we've got a sun shade on the front of the space craft that points at the sun all the time. It heats up to about 390 degrees Celsius and - which is enough to melt a great deal of materials. And we're able to use that along with thermal blanketing to keep the rest of the space craft and the instruments relatively cool so that they can do their job. At the same time, we do come down close over Mercury which, of course, is hot and that does tend to heat up the space craft and then, once that we actually get into orbit, we'll be going up to much higher altitude.

FLATOW: Mm.

Dr. MCNUTT: The orbits are 12-hour orbits and when we go up to the higher altitude, the space craft cools off and then we'll be coming back in and heating up again. And of course, that's the same sort of thing that happened briefly during the fly-by that we just went through in January and in these coming up. So, it's a very - it's a very tricky thing you have to worry about if you were at the Mercury and looked up at the sun, it would be about 11 times as hot as the sun at noon on the Earth.

FLATOW: Let me play devil's advocate for a second. Could you make a case for sending a robot like we've - all the robots we've sent to Mars to planets like Mercury?

Dr. MCNUTT: Oh, absolutely. I mean there's - we're really - Mercury is a very hard place to get to and that's why that there have only been - there's only been one previous probe that's been there and that was Mariner 10 back in the mid-1970s. And Messenger will be the first probe to actually get into orbit and to start doing the kind of assays that have been done from orbit on Mars for some time. But certainly the next stage after Messenger and after Beppi Colombo, that's an European space agency mission that's going to Mercury here one of these years. The next thing to do would be to get a probe down on the surface and to do some science up close and personal like what's going on with Phoenix right now on Mars.

FLATOW: Is there any money for it? Is there anything on the drawing board?

Dr. MCNUTT: Nothing on the drawing board for that. There were some discussion I believe with some of our colleagues in Russia in conjunction with the Beppi Colombo mission some time ago about perhaps looking at a probe to actually land on the surface. But I think they started looking at the price tag, and it did - got to be a little bit on the high side. So, right now, there's nothing on the drawing board for that, and it's not going to be cheap to do. But on the other hand, things that are worth doing usually cost you a little bit of money.

FLATOW: This is Talk of The Nation Science Friday from NPR News. Talking with Ralph McNutt, project scientist for the Messenger mission and Peter Smith, principal investigator for the Mars Phoenix mission. Let's go to phone. Sir, Rocky (ph) in Saint Paul. Hi, Rocky.

ROCKY (Caller): Hello, sir. I'm glad - I hear you guys what you're talking about. See, my Dad, I never knew him. He moved out to Seattle when I was born in '57, and he worked on all the Apollo stuff that went to the moon and whatever. And he worked on Mariner 10, and I looked on the Internet, and I can't find anything about it really seriously about what did they made and how and whatnot and is there any way I can get any of that information?

FLATOW: About Mariner 10?

ROCKY: Yeah.

Dr. MCNUTT: Usually the best - one of the best things you can do for some technical information on Mariner 10 is if you - if you use one of the search engines and look under NSSDC for National Space Science Data Center and Mariner 10, and that'll connect you back with the database at Goddard Space Flight Center.

FLATOW: Good luck to you, Rocky.

ROCKY: Oh wait. Can you tell me that one more time?

Dr. MCNUTT: Yes. NSSDC Mariner 10. Three different words, put a space between and use a good search engine.

ROCKY: OK. Thank you much. My Dad's name was Peter O'Toole.

FLATOW: Good to know. Good luck to you.

ROCKY: OK. Yeah, bye.

FLATOW: How much more sophisticated, speaking of Mariner 10, is the probe that we have now?

Dr. MCNUTT: Oh, it's far more sophisticated. You know, it's like - well, it's like with Phoenix. It's like comparing Phoenix with the Viking landers back in the mid-70s.

FLATOW: Mm.

Dr. MCNUTT: I mean, we've come a tremendous way on being able to have computational facilities on board on having spacecraft autonomy to protect these things, and indeed, you know we're just talking about the kind of instruments that are onboard Phoenix Landers and again we've got a pay load on Messenger that would have taken 10 times the mass if you try to build it back in the 1970s.

FLATOW: Mm hmm.

Dr. MCNUTT: And if it was going to take 10 times the mass, you couldn't have flown it into Mercury.

FLATOW: Right.

Dr. MCNUTT: So, things have changed tremendously and it's the changes in the technology and the reduction and the mass of the instruments and they increase this in computational power that are making all of these advances possible.

FLATOW: Pete Smith, any comment? Any comment on...

Dr. SMITH: Yeah. Sure. But we have actually set a mass spectrometer on our mission and that used to be a laboratory - piece of laboratory equipment that weighed half a ton. And we've got it down to just a dozen kilograms so, you know, there's been tremendous advances in many areas, and of course, the computers are - the old space craft in the 70s didn't have the computing power of your cell phone. So there's been tremendous advances, and we're just living in a wonderful era for that.

FLATOW: Yeah.

Dr. SMITH: You know, space exploration couldn't have been done 50 or 60 years ago. It's just in our lifetime that we're able to do these things.

FLATOW: And you also had to advance the power on Earth to track these things and keep track of...

Dr. SMITH: Oh yeah. There's a whole infrastructure that goes up. Otherwise, we wouldn't be able to communicate, and we have the deep space network that's in three places around the globe. So that we'll always have communication with our satellites.

FLATOW: Where is Pioneer now?

Dr. SMITH: Well that's outside the solar system. That's gone out to the heliopause I believe.

FLATOW: Is that third - most furthest away or is Voyager?

Dr. SMITH: No.

Dr. MCNUTT JR: Actually, if I can mention...

FLATOW: Sure.

Dr. MCNUTT JR: Voyager One is actually the thing that's the furthest away from the Earth right now. It's well over 100 astronomical units away and Voyager One and Voyager Two have both gone through what's called the termination shock of the solar wind and are actually getting in to the interaction region between the solar system and the true inner stellar space.

FLATOW: Still sending back information.

Dr. MCNUTT JR: Still sending back information. Absolutely.

FLATOW: Wow.

Dr. MCNUTT JR: I think there's about four instruments on both of them. They get tracked every day. It takes about 9 hours for the radio signals to get back to the earth. They're a long way out there.

FLATOW: Build to last. We're going to have to take a break. Come back and talk a little more with Ralph McNutt and Peter Smith and your phone calls, 1-800-989-8255. Talking space this hours on Science Friday. Stay with us.

(Soundbite of music)

FLATOW: This is Talk of The Nation Science Friday. I'm Ira Flatow. A brief program note coming up next week on Talk of The Nation and praise of political insults plus covering the Olympics in China and the broadcast returns to the Newseum in Washington and if you'd like to be part of a live studio audience there, send an email to tickets at npr.org. We're talking this hour about Mars and Mercury with my guests Ralph McNutt, project scientist for the Messenger mission. Peter Smith, principal investigativor for the Mars Phoenix mission. Our number 1-800-989-8255. We've got time for a phone call or two. David in Columbus. Hi, David.

DAVID (Caller): Hi, guys. A question for Peter and first congratulations on the success of Phoenix. My question is regarding information being released from the first TEGA oven sample besides the preliminary announcement of detecting water in that soil sample, I've got to see any other more detailed information on the results from that sample as the gas is burned off. Would you be able to share a little any of those with us this afternoon?

Dr. SMITH: Well, I'd like to. But we just got our calibration data that goes with that data set, I think two days ago, and the team is working quite hard to understand the subtle signals that they saw. And without the calibration, they've been hampered so, I'm afraid it's going to be another few days before we make an announcement.

FLATOW: What are the ovens designed to do and tell us?

Dr. SMITH: OK. We have eight tiny ovens, and we deliver samples from whatever part of the surface we want to take them from. They go into the little ovens, and then we slowly heat up to as much as a thousand degrees centigrade. And as you heat up through those temperatures, the material inside undergoes changes of various types particularly if there's say a carbonate or a sulphate or what we call a volatile mineral that has gases involved with it. And the gases get driven off at those temperatures. So you now the temperature which gas comes off, and then the gas goes into a mass spectrometer, and you know all the elements that make up the gas, and you can really do a very sensitive analysis of the minerals and even the organic materials that might be on that sample. So we have eight chances, and we've used one so far of a surface sample.

FLATOW: And so far, what we heard - is this correct? That the soil is fertile enough that you could grow broccoli in it, something like that?

(Soundbite of laughter)

Dr. SMITH: Well, the soil is a alkaline soil and those are fairly common on the Earth, and I think the idea was asparagus grows in an alkaline soil.

(Soundbite of laughter)

Dr. SMITH: And if you brought it back to the Earth and...

FLATOW: You got my winter vegetable roll.

Dr. SMITH: Have it fertilizer and water, you might be able to grow some.

FLATOW: Wrong winter vegetable. Now, we only have about a minute or two left. Let me ask you, Ralph, what are you waiting for? Any data that's in a hopper and being crunched that will tell us something different? Anything?

Dr. MCNUTT: Well, we're still crunching through quite a bit actually and we're actually going to be giving some of the results tomorrow at what's called the Coast Bar meeting in Montreal or Canada and the biggest thing right now is working on all the planning and all of the computer loads for having a successful second fly-by on the sixth of October where we're going to see the rest of the planet for the very first time.

FLATOW: Any preview of those results for tomorrow? Just give us a little taste.

Dr. MCNUTT: Well, there's going to be some more details on what we've talked about before again. More details on the planet. We've actually got - there's actually a special issue of Science Magazine that came out on the Fourth of July.

FLATOW: Right.

Dr. MCNUTT: They get on the newsstands today that has a lot of the Messenger results in it.

FLATOW: All right, we'll I won't press you anymore on that.

Dr. MCNUTT: OK.

FLATOW: All right. Thank you both, gentlemen for taking time to be with us today.

Dr. MCNUTT: Thank you.

Dr. SMITH: Thank you, Ira.

FLATOW: Welcome. Peter Smith, principal investigator for the Mars Phoenix mission and Ralph McNutt, project scientist for the Messenger mission that is in Mercury.

Up next, predicting earthquakes. Yeah, you think you can do it? Maybe for scientists who study earthquakes being able to predict a quake to give people let's say enough time to prepare or to get out of the way.

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