MS. DIANE REHMThanks for joining us. I'm Diane Rehm. On August 6, the NASA space rover, Curiosity, is set to land on Mars. Scientists are hopeful a more thorough exploration of the closest planet to Earth will help determine whether life ever existed or could exist on Mars. Washington Post science writer, Marc Kaufman, has written an e-book. It's titled "Mars Landing 2012." He joins me in the studio along with James Green, director of planetary science for NASA.

MS. DIANE REHMI invite you to join us as well, 800-433-8850, send us your email to drshow@wamu.org, follow us on Facebook or Twitter. Good morning, gentleman. Thanks for being here.

MR. JAMES GREENGood morning, Diane.

MR. MARC KAUFMANGood morning, Diane.

REHMJim Green, I love the space rover's name, Curiosity. It's just perfect.

GREENYes.

REHMBut why of all the planets in the solar system, why is Mars the target for this exploration?

GREENWell, Mars is probably the most Earth-like. Even though Venus is the size of Earth, the temperature on Venus is so high, and the pressure is so huge, we'll never be able to put humans down on Venus. But Mars really has many of the conditions and the ability for us to be able to -- if we're gonna step out of low Earth orbit, be that ultimate destination for humans.

REHMOf course Mars is closest to the Earth. You've already done a flyby. What did you see when you all went by?

GREENWell, we've actually flown by Mars a number of times in the early '60s, and at that time, what we saw was a very cratered planet, more moonlike at that time, and it was very disappointing. But by the time we put spacecraft in orbit and had the opportunity to really study the planet, and most recently with our Mars reconnaissance orbiter with high resolution imaging, we see that Mars is just so fantastic. From a major geological perspective where there are places that look like water has flown, and a lot of water in fact.

REHMWater.

GREENWater.

REHMThat's really remarkable that you would not have seen that on first flyby, but further, further, further examination.

GREENThat's right. What we have seen is evidence of past water.

REHMI see.

GREENAnd most recently, we've seen indications of water seeping out of aquifers, flowing down crater walls. Now, the atmosphere of Mars is really thin, and so consequently, the water actually evaporates or sublimates quiet quickly, and so it's been very hard to see. But indeed, there's a fair amount of water that's trapped in the ice and trapped underneath the surface.

REHMJim Green, director of planetary science at NASA. Turning to you Marc Kaufman, you've written that the landing is billed as seven minutes of terror. Tell us about that.

KAUFMANYes. This is what, one of the many things that makes this such a remarkable mission. Because this is such a large rover, it's one ton compared to I think a third of that from the last rovers that came in. They had to make a different kind of landing, and incidentally, it's the kind of landing that they ultimately would have to do if they ever brought humans. They couldn't do something small. And so it comes into the atmosphere, the Martian atmosphere at 13,200 miles an hour, and it has less than seven minutes to go down to zero. Now, it's hard...

REHMHow does it do that?

KAUFMANWell, there -- it has six...

REHMWith great difficulty.

KAUFMANWith great difficulty. It has six or seven different maneuvers that it has to do in terms of putting its heath shield forward, getting a parachute to go out, doing S-curves, but the big thing, the big advance here is that the module separates very close to the surface, and a descent module hovers over the surface for a while at about 60 feet, and then it just very slowly, slowly, slowly drops the rover. It's called a….

REHMGently.

KAUFMANGently, gently. It's 1.7 miles an hour hopefully at that point. If it's not then we're all in trouble, but it is -- that is called a sky crane maneuver, and it's never been used before, and here's the fascinating thing to me as I went out to JPL, the jet propulsion lab and spoke to people about it. All of these things have been tested individually, but of course they cannot be tested as a system. And so this is a test landing.

REHMAnd it's going to take you said from the time this hovers to the time it actually lands, how long?

KAUFMANThat is only about -- I think that's less than a minute.

REHMWhoa.

KAUFMANIt's seven minutes from the time that it enters the atmosphere...

REHMI see.

KAUFMAN...and then it goes through all these other maneuvers that slow it down in terms of friction, in terms of the parachute and so on. But again, never before tried.

REHMAnd Jim, will you be able to see this maneuver?

GREENNot exactly the way you might think, but indeed, the whole system will be beeping tones back to us. We'll be monitoring that from spacecraft that are orbiting Mars, and also from one of our very large dishes, a 70-meter dish out in Goldstone. And so we'll understand based on the timeline where it is in each one of its processes so that it -- we'll be assured that it lands safely by the end of that.

REHMHow far away is Mars, even knowing it's the closet planet to the Earth?

GREENWell, getting to Mars is much like football, and that is, a good quarterback always throws his football in anticipation of where the receiver is going to be, and that's what we've had to do with Mars. So Mars actually is a fair distance away from us. It's not the closest at the time period. And when it enters the atmosphere and gets down to the ground as Marc mentions that's seven minutes, but light travel, which is how I would measure distance in this case, is about 13-and-a-half minutes. So when we receive the signal that the Curiosity rover has started its path down to the ground, it will already be there.

REHMHow long ago did this vehicle begin its journey?

GREENWell, we launched it in November 26. It was our Thanksgiving to get it off the ground in good shape, and it's just been doing wonderful ever since then. So it takes about nine months to get it there.

REHMNine months.

GREENYeah. So that's quite a throw from the quarterback.

REHMAnd now explain why the presence of old water is so important.

GREENWell, what we're doing with Curiosity, is we're landing it in a region of what we would call past Mars. It's deep in a crater where there's clays and sulfates. Those have been deposited by water, and probably an ocean-like system.

REHMHow large is this crater?

GREENOh, the crater's pretty huge. You know, the beltway would just be around it. But this particular region that we're landing is down in the floor of the crater, so from my perspective, we're really going back in time when Mars was wet, and where's a potential for life to have occurred at that time.

REHMSo you're saying you're going down farther than the equivalent of the Grand Canyon here on Earth.

GREENThat's a good question. I didn't think of it that way, but indeed we are going very deep down into this crater, down to where the strata will tell us about the past Mars, and it's probably deeper than the Grand Canyon, yeah.

REHMMarc.

KAUFMANWell, and just another way to look at it is that there's a large mountain in the middle of this crater, and the mountain is three miles high, and I don't know that it goes up as far as the rim of the crater, but -- I'm not sure about that, but it is -- you can tell that the distances here are fairly large. And one of the many things that makes this mission different than anything that's ever been done before, is that the rover is going to climb some of that mountain.

KAUFMANIt's going to first drive to it, find things that are at the bottom of it in terms of the clays and the minerals that Jim mentioned, and then it's going to try to climb up.

REHMOkay. Now, wait a minute. You've got me really excited here. This rover is going to land at the bottom of this crater?

GREENCorrect.

REHMBoy, you gotta have a bulls eye for that.

GREENWe do. We do. It's very difficult, in fact, you can probably imagine somebody hitting a golf ball in New York and putting a hole in one in L.A., and we've practiced that from our previous missions. We've modeled the atmosphere of Mars. We know a lot about Mars and it's conditions and it's atmosphere, it's temperature, it's pressure, and consequently that means what we call the landing ellipse for this particular mission is shrunk down to about 11 or 12 kilometers by about 20 kilometers.

REHMWhoa. So at the bottom of the Grand Canyon for example, can I expect to find life on Earth as it was? Why is this crater giving you such clues, Marc?

KAUFMANWell, the reason why -- I mean, certainly we would find Earth has been just pioneered by a lot of different species, so we wouldn't necessarily find a different form of life, a different species at the bottom of the Grand Canyon, but I think what Jim was referring to earlier is that the bottom of the crater is primordial Martian rock, and as a result, it can have in it what might have been alive 3.5, four billions ago.

KAUFMANAs it turns out, four billion years ago the Earth was kind of a mess. The Moon had been created not that long after. It was just like not a place where life could begin, but there is good reason to think now that Mars was a place like that.

REHMMarc Kaufman. He's science writer with the Washington Post, author of the National Geographic e-short titled "Mars Landing 2012." Short break. We'll be right back.

REHMAnd joining me here in the studio, Jim Greene. He is director of Planetary Science here at NASA headquarters. And Marc Kaufman, science writer with the Washington Post. He's author of the National Geographic e-short titled "Mars Landing 2012: Inside NASA's Curiosity Mission," which was released this month. Marc Kaufman, some people have said this is the most important NASA mission of the decade.

KAUFMANAbsolutely. Speaking earlier last week with John Gruntsfelt who's the chief scientist of NASA and that is specifically what he told me. He said that this one is the big one, and the reasons why, if I could just lay it out for a sec.

REHMSure.

KAUFMANOne, just the landing will require a level of competence and of innovation that's never been seen before. That then allows the lander to go into a crater, which again has never been done before. Always we landed on flat plain. So there's that huge engineering technological advance. Second, this is the first astrobiology mission, astrobiology being the search for life beyond Earth since Viking in the 1970's.

KAUFMANViking came back with disheartening kind of information. Astrobiology was taken off the table the most part. The last 10-15 years the possibilities for life beyond Earth and particularly on Mars have increased dramatically. And so it is now -- it makes sense to go back to Mars, and with greater refinement and greater know-how to look for the potential signs of life or the building blocks of life.

REHMWhat time, our time, is the landing expected to happen?

GREENWell unfortunately Eastern time, 1:37 in the morning. But -- and we'll know the whether or not it landed safely by two o'clock in the morning.

REHMWhere will you be?

GREENI'll be at the JPL, at the Jet Propulsion Lab.

REHMOkay. And we've gotten a number of emails saying will it be possible for people to view the landing live from Earth with a powerful planetarium-type telescope?

GREENNo, not from a telescope. However, what's even better is to be able to log onto www.nasa.gov/mars and be able to find a venue. We have a Google map. We have well over 300 outlets all across the country, actually a number in the world, for which we're going to pick up the feed from JPL. So you don't have to be at JPL or in the control room. You can actually see what's going on. And there'll be a variety of events and activities at all the NASA centers and many museums in the United States. So that's the first place I'd go.

REHMAll right, give me that email again, that address again.

GREENIt's www.nasa.gov/mars.

REHMSlash mars, okay. We'll have that up on our website. I'm not sure I can stay up that late, but I'm sure a great many people across the world will want to see that. Here's an email. "Your guest mentioned that water evaporates very quickly on Mars. Is there a water cycle as on Earth? Where does the water go when it evaporates?" Jim.

GREENThat's a great question. And, in fact, Mars has lost an enormous amount of water. We believe Mars had significant amount of water in its past, many billions of years ago and that's why Curiosity is going back in time to look at those regions. And so, we want to know what happened to it, why it changed so radically over the years. And the oceans evaporated ended up in the upper atmosphere, and then the oxygen was stripped away.

GREENPerhaps because the planet did not have a magnetic field or it lost its magnetic field, perhaps because the planets gravity isn't like that of the Earth. You know, it's about 1/6th the gravity of the Earth. So, those are mysteries that we're also looking into, and it's part of an overall puzzle as to whether Mars would have been habitable in the past. And that's actually what Curiosity is doing. It's looking for, going back in time looking for whether Mars could have been habitable in its early days.

REHMAnd the trick here is habitable in a life form as we know it, Marc.

KAUFMANAbsolutely. And we don't really know how to look for life as we don't know it per se. They're looking for organic compounds, meaning carbon-based compounds and they're looking for environments, little habitats that on Earth would appear to be conducive to life or that we know are conducive to life. And you could perhaps extrapolate from that on Mars. So, yes, they're not looking for life as they did at Viking and came up with kind of controversial and still argued about results.

KAUFMANBut rather they're looking for those building blocks and the habitats to say, hey, it could have happened here. And then hopefully in the future they'll go and say, hey, it did happen here.

REHMAren't there even theories that Earth could have been formed by one, I don't know, something flying off the moon or Mars and creating the Earth?

GREENPanspermia, it's a theory that I believe would be fair to say has some serious backing. The logic of this is that because Mars back in 4 billion years ago or so appeared to be more habitable than Earth. It's possible that a meteorite could have struck Mars, kicked out some kind of rock that had microbial life in it. We know that these microbes, these extremophiles can last for a long time under remarkable conditions.

GREENAnd so potentially, it could have flown around the universe or the solar system for a while, landed here in D.C. And, boom, there you go, we're all Martians.

REHMNow, are you looking to lift rock out of that crater and somehow have it transported back here to Earth?

GREENThat's a great question. We would to be able to do that because clearly the analytical ability that we have here on Earth is far greater than anything we can stick in a rover and sit down on the ground.

REHMYeah.

GREENBut this is actually the next logical step to really be able to look at these past environments on Mars. Look for complex organic molecules, make atmospheric measurements of importance for which we're quite tantalized by the methane that we see Mars emitting on a seasonal basis. So it's a huge step from the ability to put such a complicated set of experiments down on the ground, but it's really the next step in a long line of activity for which we do hope to bring back samples from Mars.

REHMWhat kind of organism could one hope to find within the rock, within the crater? Marc.

KAUFMANWell, again, they're not looking for the organism right now. They don't have the capacity or the level of sterility. But what scientists have found in the last 10, 15 years is that you could go down into the bowels of the Earth and they do that is South Africa.

REHMRight.

KAUFMANAs deep as you can go and you're going to find in the water deep underground that there is microbial life, little bacteria, little other.

REHMThat we've never seen.

KAUFMANWe have never seen, we didn't know until recently existed. And as it turns out there is more life below the surface of the Earth than there is above. And that includes the bottom of the ocean.

REHMWhat kind of life?

GREENAlmost all single cell microbes. I mean, that's kind of what life's all about and for 3.8 billion of our years -- no, three billion of the years on Earth that there has been life, that's all there was. So they're looking for that kind of stuff.

REHMOkay. Well, help me understand exactly then. You're not looking for life.

GREENCorrect.

REHMYou're looking for past existence of water.

GREENYes, in addition to the environment of that past. The clays that were deposited when there was an ocean there. The sulfates that were deposited because of the evaporation cycle that occurred. All the deposition that created Mount Sharp, which is at the middle of this crater that we're going to walk up is really a time capsule for us. And so, it's not the huge step Viking was, well let's get on and look for life.

REHMYeah.

GREENBut we realized that the tough part about actually understanding what we're measuring and saying is life. So we've stepped back from that and we've said these are the next steps that we must make. We must look at the isotopes of carbon. We must look at the organic materials. We must see if there's an opportunity for complex organic materials to be combined that might be the beginning of life.

REHMOkay. So this Curiosity I'm dying to see it, lands at the bottom of this crater. How steep is the mountain it must climb? Marc.

KAUFMANI'm afraid I don't know the exact angle, but I'm told that it is relative -- well some parts of it are cliff faces, rock faces and that's where the geologists will have a field day as it were.

REHMOkay. And how does Curiosity have the wherewithal to get up this cliff.

KAUFMANOh, you know, it won't go up the cliff but rather go up around some valleys, you know, going up the mountain. It has a battery to power it and it has a design that allows it to be very flexible as it goes up so it can even be at an angle.

REHMHow do we know that a nuclear-powered vehicle may or might interact with the atmosphere on Mars?

GREENWell the nuclear powered vehicle really is from plutonium 238. It's really from an isotope point of view, generates helium nuclei in a way that we can take the heat from that and generate electricity. We don't anticipate that the reactions that occur inside the rover of this process will affect the environment at all. So very low level of radioactivity, but it's hot enough that the heat then does the electricity, charging the batteries and allows us to move.

REHMOkay. And describe for me how the rover gets at the substance you all want to see.

GREENWell it does it in many fascinating ways. One of the experiments is called chem.-cam it sits on top the rover. And the mast at the very top, it fires a laser and that laser will impinge on a rock and it's intense enough, 10 or 20 feet away, to heat that rock and allow the atoms in the rock to emit radiation. And then we're going to look at that. And that radiation will tell us hey that's a fascinating rock.

REHMSuppose you create an earthquake.

GREENI doubt -- no, I don't think we'll have any chance of doing that.

REHMAn earthquake or a Mars-quake.

KAUFMANA Mars-quake.

REHMA Mars-quake. You don't think it would do that?

GREENNo, no. Another way, of course, is that we have a drill and we'll be drilling into the rock. And we also have a scoop where we can scoop up (word?) material.

REHMAnd then from within...

GREENWell those then go into a port into a couple instruments. One is called SAM, which is the sample analysis on Mars instrument.

REHMOkay.

GREENThat's the one that will look at the isotopes and will really understand the complex organic possibilities that it could measure.

REHMAnd then transmit that information back to the earth laboratories.

GREENCorrect. And it does that in a rather unique. It actually radios up to another orbiting satellite that we have around Mars. And we have a couple options. The Mars reconnaissance orbiter, another one is Mars odyssey. And then when they get in position, they radio that signal back to earth.

REHMAnd you're listening to "The Diane Rehm Show," beaming out to you from the planet Earth, but my goodness who exciting. You must be excited.

KAUFMANOh, absolutely. This is just really a thrill.

REHMBut that seven minutes.

KAUFMANAnd millions of people around the world will be watching this. Something that I guess I knew but didn't fully understand is the extent to which the United States and NASA own Mars. And I don't, by that, mean that we have property rights to it.

REHMPut a flag down?

KAUFMANWell, there have been only six successful landings on Mars and all of them have been American. There have been 44 missions to Mars and less than a third of have succeeded and all of those have been -- or many of those have been American. So, that is one of our great strengths around the world and why a lot of people globally will be watching us.

KAUFMANAnd, two, I think it's just an enormous example of American soft power and why I just, as a journalist and also as a citizen, hope that the Mars program doesn't get cut as it looks like it might be, because Mars is what we do really, really well. We are exceptional about that.

REHMNow, President Obama has cut some moneys from.

GREENIndeed. President Obama has made some tough decisions. I know we can't do everything. And these are austere budget times. And I'm delighted to say that in a balance that has to be enabled through a budgetary process, we have an exciting planetary program. Indeed right now all our attention is pointed to MSL. We are also planning potential future missions to Mars. And we're doing that now in a very unique way that we have not done before.

GREENAnd that is we're working with the human exploration portion of NASA. So we're thinking about what are those next steps that we can do together. And that will be exciting because human exploration will mean -- different types of measurements will need the science measurements that we make, but also different kinds of measurements. And by working together, we hope to be able to put humans on Mars sooner rather than later.

REHMAll right, let's go to Amagansett, New York, and take a call from Neil. Good morning, you're on the air.

NEILGood morning, Diane.

REHMHi.

NEILLove your show.

REHMThank you.

NEILMarc and James have been -- and I've been reading, in fact, for years now, about having found water on Mars. And I actually have three questions pertaining to that. First, how has this water been detected? I mean, is it with telescopes? Is it with probes that have actually landed, you know, unmanned probes that have previously landed?

REHMOkay.

NEILMy second question is when you go investigate in to find past existence of water, how do you know it was water and not some other liquid?

REHMOkay.

NEILThree, when we say water, is it water as you and I know it? Are we talking tap water? Is it some other weird alien isotope version of water?

REHMAll right, thanks. Jim?

GREENOh, wow, that's a set of really great questions. And it turns out -- we've looked at the water resources on Mars in many different ways. One of the first ways is from our orbiters. We're looking at geological features that we know where rapidly moving liquid on the surface has shaped, And in fact there are several locations on Mars, which looks like a delta.

REHMAll right. Hold your answers to the other two parts of that question. We've got to take a break here. We'll get to whether it's water or something else when we come back.

REHMAnd welcome back. I am looking at a photograph of Curiosity and I must say -- I know you won't like this, but it's adorable.

GREENWell, thank you. I think so.

REHMIt really, really is. Tell me how large it is, Marc.

KAUFMANIt's about 10' long. At the top of its mast I believe it's 7' high. It's approximately 2,000 pounds, has ten instruments. And in all of these criteria it is much, much larger than anything that's been on Mars before. What it also has -- all of the rovers have had a certain level of ability to make decisions on their own. Not artificial intelligence, but, you know, there's a rock here so, you know, you don't...

REHMRight, move over here.

KAUFMANExactly. This one has a much higher level of that kind of decision making. Again, JPL does not say it's artificial intelligence but I was speaking to one of the rover drivers and what he said was, you know, he stays up at night thinking, all right we're going to know what decisions Curiosity made while we were asleep and we could see that. But we won't know what it's thinking, how it came to that process -- to that decision. And I just found that to be a fascinating kind of insight.

REHMWell, the great concern we all have is what happens if there is some say slight damage in the landing process, is there an ability to correct, Jim?

GREENWhat will happen is after it lands on the surface there'll be a time period for which we will do an assessment of its total health. And if there is a problem, some anomaly that'll occur we'll either begin the process of correcting that anomaly. If it's something mechanical, then we'll go into the process of accommodating it. And then we'll modify the plan and then execute a variation of it.

REHMAnd how long do you expect it will be there?

GREENWell, the plan right now for Curiosity to really complete its mission objectives is about two years, which is actually one Mars year it turn out, 670 days.

REHMAnd then what would happen to Curiosity?

GREENWell, Curiosity depending on itself could indeed continue on. We call that an extended mission. After you meet your objectives you're going to find many, many, many new things and it's going to want to investigate those more thoroughly. And that condition, which is just the happiest of conditions, we're going to let it do that. And it's got the ability to last many years on the surface.

REHMI'm hoping that our listeners will now go to drshow.org. You can see for yourself Curiosity, just absolutely adorable. I know my colleague Ira Flatow, host of Science Friday, would not call it adorable, but I feel it is that way.

KAUFMANDiane, if I could just...

REHMSure, go ahead.

KAUFMAN...along those lines. The two previous rovers that went to Mars, Spirit and Opportunity that landed at the same time in 2004 I believe, they each were supposed to go for, what was it, about 20 weeks or so.

GREENNinety days.

KAUFMANNinety days. One of them is still going.

REHMWow.

KAUFMANThe other went for until I think 2009. So that's a way of saying that these things can really last. And each of them took on this kind of personality of the little rover that could. You know what I mean?

REHMYeah, yeah.

KAUFMANYou know, they would get stuck in a sandpit and then they would get out. They would go down into a small crater and by god, you know, what were they gonna see? So I think there's a real hope from Mars' enthusiasts and then also from NASA that that kind of -- what you just said, that this is kind of an adorable thing, that that will get communicated in some way.

REHMAll right. The bad question though, how much does all this cost, Jim?

GREENWell, Curiosity cost about 2.5 billion and took at least eight years to get together. It has a number of international people and instruments that are participating in the program. And so it's quite an endeavor. I mean, it really takes a long time to do these things properly.

REHMSo when you say a number of international groups participating here, I mean, could there be competition as to whose planet Mars really is? I mean, if the Russians are participating, if the Chinese are -- how do you arrive at whose planet...

GREENWell, certainly what's happening now, the European Space Agency is planning a mission for 2016 and also another mission for 2018. And the reason why they're on those boundaries is because there's an alignment for which you then, as I mentioned with the football analogy, throw the ball and then...

REHMOr the golf ball.

GREEN...yeah, and get the receiver to catch it. And those alignments occur every 26 months. So ESA is planning an important program, probably an orbiter first and then in the 18 timeframe they'll also have a rover, a lander. And the Russian Space Agency's also been very interested in Mars for the entire length of the space age. And they're still going to be a player and their plans are to work with ESA and grow their participation in that effort.

KAUFMANAnd to further answer your question, under the space treaty it is -- individual nations cannot own any part of a celestial body.

REHMThank you, thank you.

KAUFMANHowever, this is something that is an anomaly that is fascinating. Individual companies, the United States alleges or asserts -- and I think a number of other countries do -- can. And this is looking forward to the time when perhaps there will be mining on Mars or mining on the moon.

REHMAnd don't you have some private corporations that are already involved?

KAUFMANAbsolutely. There's the Shackleton Energy, which wants to mine water at the bottom of the moon. And one of their partners I believe is Boeing. So yes, there is a huge growing space industry out there.

REHMHere's a Tweet from Erza (sp?) . She says, "NASA put a bunch of people's names on a chip on Curiosity. Even if it's just ones and zeros, I'm happy to be involved somehow." Tell me about that naming project.

GREENWell, we did post on our web many years ago, an opportunity for people to submit their names. And indeed I was happy to do that myself and our names are indeed printed on a chip and that's on Curiosity now.

REHMAll right.

GREENIn addition to that, there's a nice little plaque that's sitting on the top surface that's signed by John Holdren, president Obama's Science Advisor and President Obama.

REHMTerrific. Let's go to New Orleans. Good morning, Ian.

IANGood morning. I had a question. One of your guests has said that there was a seasonal release of methane from Mars.

REHMRight.

IANAnd I was curious, is there a non-organic process that could account for the release of methane and its seasonality?

REHMJim.

GREENYes, indeed. Methane, as we know here on earth, the biggest producer is cows. We don't expect any of that complex life to be on Mars. But even the smallest microbial life will emit methane. But there is a non-biological process, it's called abiotic for which deep inside Mars, perhaps if there's magma and they certainly have to have water and other minerals, the combination of heating the water can produce methane.

REHMYou both referred to this Mars mission as really so important. I'm going to be the down sider. What happens if it fails, Jim?

GREENWell, you know, landing on Mars is tough and there's no doubt about it, our record hasn't been great. Mars has been the one that's won. But I really look at it on the bright side. I think we've done everything humanly possible to make this a successful mission.

REHMI understand that, but what happens if it's not, Marc?

KAUFMANI think pretty clear what happens is that the budget gets shrunk even more than it is.

REHMEven further, yeah.

KAUFMANI mean, I think that the cuts proposed now for 13 hours, something like $300 million.

REHMPoor Jim, I realize he doesn't want to talk about this at all.

KAUFMANHe doesn't want to talk about it. And also when he was referring earlier to the European/Russian mission, that used to be a European/American mission. And we broke our agreement with that. And then the Europeans brought the Russians in. So again, we're in this remarkable...

REHMVery important.

KAUFMAN...we're in this remarkable situation. We know how to get to Mars better than anyone. It is hard, but we know how to do it better. And the question is, are we going to walk away from that?

GREENNow I'm trying not to be overconfident, as I said, but indeed if there is a bad day on Mars, what we're going to do it we're going to pick ourselves up, figure out what went wrong and make the next step a better one. And that always comes from detailed analysis of all aspects of the technical capability of the system called entry descent landing to get it down on the surface and the rover itself.

REHMHere's an email from a middle school math teacher who says, "I would love to develop lessons for my students that connect to the Mars mission. What resources for teachers does NASA have?"

GREENOh, that's another great question. There are several things that have been posted to our website that are about educators who can use the NASA search engine and you can say Mars lesson plans. And there are a number of things that are currently available that ought to help her. You know, math objectives for every one of the grades, you know, providing some excitement to the kids by implementing those through our space program and some of the tough things that we have to do is always important for the kids I think.

KAUFMANThere also were the Mars Society, which is a group of citizens and they have a lot of stuff up. And there's an organization called Explore Mars which has been very active in putting together Mars parties and Mars information and Mars videos, whatever. They have a website called getcurious.com.

REHMDo you think there are going to be an awful lot of people staying up until 1:30 or 2:00 on the 6th? Do you expect that?

GREENI think that this is really going to be a global phenomenon.

KAUFMANYeah, you know, there might not be as many people on the east coast of the U.S. as some other places just because it's so late. But around the world it has a potential of being not quite an Apollo 11, you know, first time on the moon but because of all the ways in which it's unique it could almost reach that.

REHMAll right. To Salt Lake City, Utah. Good morning, David.

DAVIDYes, thank you for taking my call.

REHMSurely.

DAVIDMy father was involved in the space program pretty much from its inception and eventually he wound up at (word?) essentially restructuring the booster program after the Challenger disaster. After his retirement in the '80s he started to tell me stuff. And he said that in the '60s around the time that Kennedy was talking about going to the moon, he was in workgroups -- small workgroups with some of the pioneers of rocketry saying that, well the moon is great, but let's think about Mars. And he didn't reveal much to me, but I'm wondering if any of that early speculative work and conceptual work survived.

REHMJim.

GREENIt does. From a historical perspective, of course, it has developed the technology of the times for which we have improved our technology by several orders of magnitude since then. But even Wernher von Braun in the '50s was dreaming about going to Mars. You know, Mars is in our psyche ever since the telescopes got powerful enough in the late 1800s and they thought canals were there. And the excitement of...

REHMThe red planet.

GREEN...the red planet and, you know, "War of the Worlds" from a cultural perspective and literature perspective, H. G. wells, et cetera. You know...

REHMPoor Pluto. We have to remember poor Pluto and you're listening to "The Diane Rehm Show." You know, I can remember in grade school seeing that line of planets and memorizing them and Pluto all the way out there on the end, which is no longer regarded as a planet. Marc, tell us about Robert Bigelow's plans for space motels.

KAUFMANWell, this is -- he has the rights to use some of the inflatable habitats that NASA put together some years ago -- space habitats. And he is one of dozens, at this point, of very wealthy people who are investing in the space industry of the future. What he -- he himself is a motel mogul, made a lot of money building motels and so the idea is you build these. He has made an agreement with Elon Musk of SpaceX to, in the future, have SpaceX rockets deliver people...

REHMElon Musk who made his money with PayPal, didn't he?

KAUFMANExactly. And has subsequently developed SpaceX into this remarkable company that has twice now orbited the earth with capsules and once docked with the International Space Station. But the idea is that you would then like, okay it's your honeymoon, you wanna go out to the stars. You get onto a rocket, you go boom and you go out to potentially something like a habitat. And...

REHMWell, didn't somebody once have the idea that as the earth became overcrowded, you would create these cities between here and Mars and everywhere else?

KAUFMANYes, I mean, that is certainly possible or something that has been conceived. But there's also this strong kind of back current from people like Stephen Hawking of hey, we have to learn more about Mars. We have to learn more about getting to Mars because we're going to need it as a place to go as a species sometime down the line.

REHMDo you believe that?

KAUFMANDo I believe that? I don't see how it would be possible to, as they say, terra-form Mars so that it could be lived in by a lot of people.

REHMNow, yeah.

KAUFMANBut who knows? I mean, you know, we're talking about things that'll happen over centuries rather than years or decades.

REHMWhat do you think, James?

GREENI think Marc is right. The -- and you are too. In other words, our steps -- our first steps are really to understand everything about Mars we possible can from a scientific point of view, how it was put together, how water exists on that planet and what resources we might be able to use by going to Mars.

REHMJim Green. he's director of planetary science at NASA. Marc Kaufman, science writer with the Washington Post, author of the National Geographic "e-short" titled "Mars Landing 2012: Inside NASA's Curiosity Mission." That mission Curiosity scheduled to land on August 6. We'll all be watching and I get to be the first person on Mars. Thanks for listening all. I'm Diane Rehm.

KAUFMANThank you, Diane.

GREENThank you very much.