Planetary Radio: Space Exploration, Astronomy and Science - Former JPL Director Bruce Murray on the Persistence and Importance of Water Ice

Episode Date: October 19, 2009

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Former JPL Director Bruce Murray returns to 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. One more conversation about water and ice this week, but we'll have it with the man who first realized that, under the right conditions, water ice could last millions or even billions of years in a vacuum. Our own Bruce Betts will join us for this conversation with his mentor Bruce Murray. Dr. Betts will stick around for another edition of

What's Up? and we'll learn who has won the DVD collector's edition of the first three seasons of the universe from the History Channel. Hey, if they're really gas giants, why don't asteroids pass right through them? Emily Lakdawalla knows why, and she'll share the wealth in Q&A. That's gone underway with Bill Nye, who notes that space and politics seem to have become bedfellows. I'll be right back with Bruce and Bruce. Hey, hey, Bill Nye, the planetary guy here, vice president of Planetary Society, this week speaking to you from a dormitory room on the campus of Cornell University, my alma mater. I'm here to conduct some business about alumni affairs, but I will also have the great honor of doing the Astronomy 101 lecture in the very same lecture hall where I took it from

none other than Carl Sagan, one of the founders of the Planetary Society. It's quite an exciting trip for me, really. Meanwhile, space is becoming politicized. That is to say the politics of space are becoming prominent in the news. That's because it's so important. We've got to sort out what to do with our tax dollars so that we most effectively explore nearby star systems, our own star system, and then what to do with humans. Humans have been exploring space for a long time, but now humans got to do something, if I may, newer and cooler. There's a lot of people want to go back to the moon, and there's a lot of extraordinary money to be spent on sending people to the moon, but instead, I claim what we need to do is make the human next destination

Mars, and this is the flexible path as brought down by the Augustine Commission. He was the former head of Lockheed Martin. In order to send people to Mars, we have to find intermediate destinations so that we can make sure we do a good job. And the obvious ones are asteroids. And you know why? Because if the Earth gets hit with an asteroid, it is, as they say, game over. So we hire politicians by voting to sort out what to do with our tax dollars. That's right. Space is politicized. Explore distant star systems, our own star system, asteroids, and then the eventual goal of sending human geologists to Mars to look for signs of water and life. It'll change the world. I know I've said it before, but it's important. The president had

a star party outside for crying out loud with 20 telescopes and school kids. The head of NASA, the administrator of NASA, Charles Bolden, said, maybe I didn't really want this job. I'm really a fly guy. I really like exploring space in my own space shuttle. So we've got to sort this out. We are doing what we can to influence politicians with regard to what to do next in space. I've got to fly. Bill Nye the Planetary Guy. Long before he ran the Jet Propulsion Laboratory, even longer before he joined Carl Sagan and Lou Friedman in founding the Planetary Society,

Bruce Murray became curious about water and ice around our solar system. In 1961, he proposed that once water ice had collected someplace, it might stay right there for a very, very long time. Now, 48 years later, that's largely why scientists all over the world are looking for ice in permanently shaded corners of the moon. Dr. Murray is now retired from JPL and the Society, though he maintains his office on the Caltech campus. Bruce recently joined me at Planetary Society headquarters. Out on the front lawn, Society staff members were greeting visitors who had dropped by to pick up bargains at an inventory sale. Inside, our friend Bruce Betts joined us for a conversation about the persistence and importance of water in our solar system. Dr. Betts was once a student of Dr. Murray's at Caltech. I got to tell you,

I am really honored to have the two Bruce's here. What was the line from Star Wars? Now, I am the master. Oh, I wish. Don't try anything, kid. All right. Well, you certainly don't look like Darth Vader. Bruce Murray, thank you very much for coming back to Planetary Radio. That's Lord Murray. And Bruce Betts, the director of projects, of course, who joins us every week. You know, he's on the show every week. We're that desperate.

Yeah. Yeah. Can we talk about ice on the moon? Please. Oh, God, please. So back in 1961, 48 years ago. Don't say that. Is this one of the things I did? No, I'm afraid not.

You weren't even born then, for credit. Right. But was it 1961? Yes. Where were you, Bruce? At Caltech. But you were still a student, right? A post-grad?

Oh. No? You flatter me. I was a post-doctoral fellow there. Oh, a post-doc. Okay, my apologies. And what led you to start thinking about these deep, somewhat dark craters, permanently shadowed craters? deep, somewhat dark craters, permanently shadowed craters.

Well, fortunately, because I can't remember, of course, what caused me to think about it, but you can't prove it either. So therefore, I'll make something up. Great. No, I think the real interest was in water. That was a pretty important substance. It still is. And so I got thinking about it, and I think the paper is actually called the stability of water on the moon. And that was the idea. How stable

is it? What's it take to get rid of it? What will cause it to stay? And that also led to considerations for the same question of Mars, because again, water is pretty important stuff there. Pretty important down here too, Bob. So that led me into what became a long-term interest, which was the stability of water on the terrestrial planets. I assume other people realized that these craters, especially the ones at the South Pole,

would have these areas up near the rim that were permanently shadowed. You know, you're going to be unhappy because I'm going to tell you I can't remember. Oh, that's quite all right. That's okay. Whether there were other people who had thought of this or not, I don't know. Nobody else had published the idea before. Well, not about the ice, just that these craters had these shadows. But apparently it occurred to you first that, you know, if they're shadowed, how long would water ice last?

Was anybody even thinking that, okay, maybe a comet hits these and they have some ice or water for a little while, but maybe it wouldn't last too long? Well, you must remember that at that time there were probably six people working on that problem in the whole world. Oh, my. Okay. So it wasn't hard to be first or second. I don't remember actually who was working on it, but I had become interested in water on the moon and on Mars, actually, also.

It turned out that I realized that the very fact that there was water vapor around there meant that there must be ice. And so the real business was that ice would form in the shadows, and it becomes very stable for very long periods of time. When you say long periods of time, what are we talking about? Age of solar system. Seriously? Depends on the temperatures you get. You had asked me beforehand. This is, I have to jump in since it's the one thing I actually remember from taking classes from Bruce Murray.

All right, there may be others. Is how, this plot of how incredibly stable water ice is, but you have to get it really cold, tens of kelvins to be, and then it becomes stable for billions of years conceptually. But I'll let the expert go back now. Longer than you're likely to live. But that was a new realization at the time. And so it made you think, well, boy, there ought to be some ice up there. Maybe we ought to start looking for it. How about Mars?

Will it be in the shadows of Mars? And on and on and on. So it got a ball rolling of intellectual pursuit. And that was the stability of ice in shadowed areas on the moon and terrestrial planets. Since then, as we said, 48 years ago that you thought about that. And that was the stability of ices in shadowed areas on the moon and terrestrial planets. Yeah. Since then, as we said, 48 years ago that you thought about that. Don't say that. Okay.

Second warning. Stop saying that. Was it really been 48 years? I'm afraid so. But it's taken that long. I mean, now, here a week ago, we had this mission, LCROSS. Now, here a week ago, we had this mission, LCROSS, and your former student here was, as we learned last week, up on Mount Palomar looking for direct evidence of this stuff in these craters. Did you find any?

There was some water at the observatory. It was less clear whether there was water in the craters, and I think we're still waiting to see. clear whether there was water in the craters. And I think we're still waiting to see. It was lacking the plume, but they've got a lot of spectral data that we haven't heard the results, and we should hear in the next few weeks. Let me know. We'll see. We will let you know. But then tell us again about how, actually tell Bruce, because this was so interesting, that, you know, it'd been a while since you'd done any observing up there. And in the meantime, they'd added the adaptive optics it wasn't quite as big a number but it's still a disturbing number for me how long ago that I fiddled around Caltech working welcome to old age Now, now. Yes, but it's amazing.

They've taken, I know, going farther back, you did observing using the Palomar 200-inch, and now they've, in recent years, with the adaptive optics systems they've got on there, it's really a whole new observatory. The images were fabulous and just a whole new capability science-wise. Great, great. And apparently, I mean, Emily Lakdawalla in the Planetary Society blog said it looks like apparently the best, certainly the best Earth-based images, I guess, were from Palomar. But as you told us last week, no plume, and they weren't doing spectroscopic stuff up there. Right. It was just near-infrared imaging.

And as we record this, the most recent check that we've made, there has still not been any announcement that the spectroscopic data from LCROSS, you know, indicating that any water got thrown up from that impact. But to be clear, there's no indication otherwise. They're just holding the data tight. Yeah. And caressing it gently.

Maybe it'll change the spots a little bit. Exactly. More from Bruce Murray and Bruce Betts in a minute. This is Planetary Radio. I'm Robert Picardo. I traveled across the galaxy as the doctor in Star Trek Voyager. Then I joined the Planetary Society to become part of the real adventure of space exploration.

The Society fights for missions that unveil the secrets of the solar system. It searches for other intelligences in the universe, and it built the first solar sail. It also shares the wonder through this radio show, its website, and other exciting projects that reach around the globe. I'm proud to be part of this greatest of all voyages, and I hope you'll consider joining us. 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. Our nearly 100,000 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. We're joined by two Bruce's, geologist and planetary scientist Bruce Murray, who is a former director of the Jet Propulsion Lab and a founder of the Planetary Society. Bruce Betts is an astronomer and planetary scientist and a former student of Dr. Murray's at Caltech. As we continued our conversation about water ice on the Moon and Mars, I wondered about the recent discovery made by the Moon Mineralogy Mapper on Chandrayaan-1, helped by the Deep Impact, and Cassini probes. I don't know if you're up on those results, this finding of this film of water and OH molecules,

but I wonder, I'll ask both of you, does that say anything to you about, Does that say anything to you about, is it evidence for, against, or not at all neutral regarding water at the poles in those craters, if there is this film all over the moon? The film itself, I think, is not, as you call it a film, is not highly relevant because it's separated. Now, there's a separate conclusion that they're putting forth from one of the set of instruments, Deep Impact, where they say that the moon is breathing water, that it's actually changing the amount, that it's coming out during the middle of the day. But it's also two observations, basically, and a very complicated inference. So I at least haven't bought into that yet. It might be true. That's really interesting because then you indicate there's some process actively putting out and bringing water in.

You get the water molecules out of the surface. Then maybe they can hop down to the polar regions over time. But that is not the one they had lots of data for, which was just from three spacecraft, that there's some very small amount of water in many places. I guess whenever you mention water and the moon, then juices start flowing in lots of people. Sometimes justifiably, sometimes there isn't much really to justify it, but the juices still flow.

The reason people are interested in water on the moon is that one, scientifically, but the more compelling reason is the idea that there may be human flight and colonies to the moon sometime, in which case water is very, very important because we don't have it, and it's very expensive to transport a spaceship full of water to the moon. So that's why I think it's worth paying attention to because if it's held up that there is a source of water on the moon that's fairly plentiful,

then it might change some people's attitude about whether humans could really build a long-term endeavor there. You mentioned Mars as well. So here's a place where we know there's lots and lots of ice, not far below the surface, sometimes right on the surface for a little while. Were you saying a minute ago, I think you did, that that was also something you were considering back there in 1961? Well, I'll say yes. I'm sure of what reaction that's going to provoke. But yes, the, yeah, I mean, water is such an important substance.

If you find it on any astronomical body, you're going to pay attention. And if it's one that you didn't think was there and you find evidence for it, that's big news. Since he won't mention, Bruce was on one of the key papers in the mid-60s that predicted the movement of water and carbon dioxide ice on Mars and interactions of the poles on or off and really pushed that field forward an awful lot in trying to understand the water and carbon dioxide cycles on Mars. Dr. Murray, did you hear the recent story that said that it's quite possible

that Viking 1 and I think it was just maybe it was just Viking 2, right, if it had managed to dig down just a few more centimeters, it might very well have hit a layer of ice. I haven't heard that yet. As I often say with rumors, good luck. Maybe it's true. But how would that have changed things? I mean, this was a time when you were still doing a lot at that little laboratory up the street.

Yeah, at Caltech. Yeah. If Viking had come up with that incontrovertible evidence. Well, as we now know, it could have easily done so had it hit a different place. That discovery on Mars of Viking actually pulling up a little bit of ice and dropping it into the lab there. How that might have changed things. Well, we knew that there was ice on Mars. Yeah.

We could see it with telescopes from the Earth, white frost and things like that. I think the nature of the space exploration activity, I won't use business because I don't find it to be profitable, but the activity creates sort of a bow wave of expectation and enthusiasm in the public and one of the things that does that is a notion of ice because ice is obviously that's something everybody understands and that it could be very important. We didn't have that experience. We didn't but if we had I think it it would have given at least a near-term boost

to Mars exploration. Wasn't his picture is hanging right above your head as I look toward you across the microphone here. You're co-founder of the Society, Carl, Carl Sagan. Wasn't he also a big believer that once we really had the tools to look, we would find water and ice all over the place? I think that's right. He and I differed because he was a chronic pessimist, optimist, and I'm a chronic pessimist. That's for sure. Seems where I learned it from.

Yes. Seems where I learned it from. Yes. And therefore he was in favor of water and ice on Mars until all possible arguments to the contrary were exhausted. I was not that way. So we had a fundamental disagreement in how we looked at things. Both are valid. Both have good reasons for them. And they were just the different temperaments that Carl and I had.

But it does point out that there is room for two good scientists to come at something from very different directions. Right. And to be quite convinced of the veracity of their conclusions. Absolutely. As long as we're on the topic and we're just about out of time, here we are in, what, the living room of this old house off of Colorado Boulevard, where you and Carl and Lou Friedman got things going so many years ago. Still fun to come by this place? Oh, yes.

It's really a beautiful old house here. I love it. And for those of us who've been around since the beginning of the Planetary Society, this is a little cathedral out here. Yeah. Any last words from the student? He is still the master.

I'm going to get back out there to the sail. I think all the good stuff is going fast. So I'm just going to thank the two of you for joining us on the show. Actually, you need to stick around because we're going to do What's Up in just a moment or two after Emily comes in with Q&A. So please,

you stay, but Dr. Murray, you sure can. Get out of here. Thanks for joining us on Planetary Radio. He is Dr. Bruce Murray, one of the three co-founders of the Planetary Society, and used to run that place called the Jet Propulsion Laboratory up the road here, up the 210 freeway from here in Pasadena. Still someone, as you've heard, who cares a great deal and has had some interesting things to say about how our solar system has come together.

Still pretty exciting to watch this happen, isn't it? It certainly is, because the watching gets better. Yeah. Thanks again. Bye-bye. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, I read that Uranus got its tilt when it was hit by another object.

What does it mean for a ball of gas to be hit? Wouldn't another object just pass right through it? The outer planets Jupiter, Saturn, Uranus, and Neptune are composed mostly of materials that are gases or liquids at standard temperature and pressure. Things like hydrogen, helium, water, methane, and ammonia. And the parts of those worlds that we can see, their uppermost atmospheres, are in the gaseous state. But if you took a ride in a space probe that could dive into a giant planet's atmosphere, it wouldn't take long before the state of things would change

because of a rapid rise in both temperature and pressure. The interiors of the giant planets behave mostly like liquids, and deep within them they actually have cores made of rock and metal, the same stuff that Earth is made of. In the early solar system, there were frequent collisions between the protoplanets and other nearly planet-sized bodies called planetesimals. between the protoplanets and other nearly planet-sized bodies called planetesimals. A colliding planetesimal certainly couldn't fly straight through the incredibly dense liquidy interior of a protoplanet, so it was absorbed. When that happened, the planetesimal contributed not only its mass, but also its momentum to the growing planet.

If the impact happened off-center, and statistics say that it's much more likely for an impact to be off than on-center, the collision could have spun the protoplanet faster or counteracted its spin, and it could also have shifted the rotation axis. Such large collisions in the early history of the solar system most likely explain the sideways spin of Uranus as well as the slow, backward spin of Venus. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt

with more Planetary Radio. Alright, as promised, Dr. Murray has left, but we still have the other Bruce here, Bruce Betts, the Director of Projects for the Planetary Society. He's joined us once again for this week's edition of What's Up from here in the living room at the Planetary Society. Welcome back. And I am the master now. Yeah, I'll call him back in here.

I will. No, no, no, no. All right. Did you get anything good at the sale? Like that T-shirt you have on? Yeah, they slapped a T-shirt on me. They didn't like it when I showed up in the referee uniform. But that's what I want to get a picture of you and Bruce Murray together.

Me with the soccer referee uniform. Yeah, that's what I want as soon as we're done with this. Tell us about the night sky. Okay. In the night sky, we've got Venus offside in the pre-dawn no sorry in in the pre-dawn we have venus and saturn very close by to each other in the eastern low in the east venus being the much brighter of the two we have mars very high overhead looking reddish in the pre-dawn also hanging out in the evening sky now over there in the east, low in the east early on.

And the evening sky is still dominated by Jupiter, brightest star-like object up in the evening, high in the south after sunset. It's the bright thing up there. On to Random Space Fact! Now I'm really sorry Dr. Murray didn't stick around. You want to hear what I would have done if you were here? Sure. Random Space Fact. Let's talk about Mars and those ice caps and the things that came out of murray papers and studies from the 60s along with others at caltech which is uh mars poles they're they're kind of weird they're asymmetric and so the permanent cap in the south is carbon dioxide ice the permanent cap in the north what is water ice on the surface, although we've learned later that it seems to be covering carbon dioxide ice.

And both poles get covered over by dry ice, carbon dioxide ice, during the winter. That's not all that random considering what we were just talking about on this show. But it's all right. It is a space fact. You're right. That's all right. Two out of three isn't bad. Shall we go on to the contest?

Yourness is blue. I beg your pardon. Okay. Forgot. Never discuss that planet. That's right. We asked you last time around about the LCROSS impact and how much time was there approximately between the impact of the centaur upper stage and the impact of the shepherding spacecraft how'd we do matt you

know this is one of those where this show is just so timely that some people actually were still able to enter after the impacts cool they had it precisely four minutes and 26 seconds but you had made it fairly loose. Closest minute. Okay. And that's exactly what happened. Because our winner, who is Jamie McAuliffe, I think he's from Illinois, Marion, Illinois. But I had to figure that out from Google Maps because all I had was his street address.

He indeed said four minutes. You're stalking the entrance. I even have a picture of his house now. Four minutes, four minutes between the Centaur impact and the Shepherding spacecraft of the LCROSS mission. Jamie, congratulations.

You know what this means? No, what does this mean, Matt? He gets the DVD copy of, what, three seasons of the History Channel's The Universe series, which you are part of. Indeed. But not in those three seasons. No, not yet. But they were excellent. Yes, three

full seasons on DVD. Very cool. The History Channel The Universe. So congratulations, Jamie. What do you got for next week? So, what was the first spacecraft to fly by Mars successfully? And Bruce Murray was on part of the imaging team for that and all of those missions at that time.

And for many years and decades afterwards. Go to planetary.org slash radio. Find out how to enter. Now, do we have to disqualify Bruce Murray from entering this competition? qualify Bruce Murray from entering this competition? If he actually chooses to enter and wins from your random.org, I'd give it to him. Yeah, I think we should give him a shirt. We'll give him a shirt. But I think everyone's got a pretty good chance.

You've got – you and Dr. Murray have until 2 p.m. on Monday, Monday, 2 p.m., October 26, to enter this latest version of the Space Trivia Contest. All right, everybody, go out there, look up at the night sky, and think about the joy, oh, joy of yard sales. Thank you, and good night. It's an inventory sale. Lou said it's an inventory sale. Oh, I wasn't thinking about this one.

Oh, I'm sorry. Oh, right, no, this is an inventory sale. He's Bruce Betts, the Director of Projects for the Planetary Society. He joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California. Keep looking

up. Thank you.