Planetary Radio: Space Exploration, Astronomy and Science - Four Decades of Mars Exploration

Episode Date: August 18, 2003

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This is Planetary Radio. of our show. The excitement is rising as surely as a very bright Mars is rising in the night sky. Five spacecraft on their way there and just a week till that mysterious planet passes closer to us than it has in 50,000 years. A fitting time to talk with someone who can provide a good sense of the 40-year history of Mars missions. That's why former JPL director Dr. Bruce Murray will be our guest. We'll find out from Bruce Betts why opera singers have nothing to do with asteroid impacts, and Emily explains why we're lucky enough to have an atmosphere circling Earth. Let's take to the air. Hi, I'm Emily Lakdawalla with questions and answers.

A listener asked, I've heard that the sun was smaller and hotter when it was young. If this was true, wouldn't the Earth's oceans have evaporated? It is true that the sun's luminosity has changed over the 4.5 billion years of its life. Current stellar formation models suggest that since the Sun was born, its luminosity has increased. This increase in luminosity probably did have an effect on the early atmospheres of all of the planets. But the terrestrial planets, which include Mercury, Venus, Earth and Mars, do not have their original atmospheres intact. The first atmospheres on all of these planets were probably destroyed by a young and active Sun. Scientists believe that just after a star forms from a cloud of gas and dust, there

is a phase called the T-Tauri stage. During the T-Tauri stage, violent winds from the Sun blew away the fragile atmospheres of light elements that formed around the young planets, leaving balls of naked rock. So where did our atmosphere and oceans come from? To find out, stay tuned to Planetary Radio. Bruce Murray's career as a planetary scientist stretches back roughly as far as our ability to send spacecraft to visit other planets. He's as responsible as any other human being for getting some of those missions off the ground.

This geologist still heads for his Caltech office every day, where he continues his research and has five students hard at work studying Mars. You may have heard him several months ago on this program, talking with Lou Friedman and Freeman Dyson. We asked Bruce to pay us another visit as we enter what may be the most exciting period of Mars discovery in human history. He spoke to us from his home in Southern California.

Bruce Murray, we're entering an unprecedented period of Mars exploration. in human history. He spoke to us from his home in Southern California. Bruce Murray, we're entering an unprecedented period of Mars exploration. There's also great excitement over the fact that Mars is about to pass closer to Earth than it has in over 50,000 years. At the risk of throwing you a softball, does that planet deserve all this attention? Does that planet deserve all this attention? Well, any planet that offers the potential for at least human visiting and bases the way Mars does clearly warrants our attention. And so, yes, I feel it does deserve it. Also, we've learned some very exciting things about Mars.

Just in the last several years, due first to the Mars Global Surveyor, high-resolution spacecraft, and then most recently from the Mars Odyssey spacecraft, which has the capacity of detecting water molecules in the form of ice within about two or three feet of the surface. The latter, that is the Mars Odyssey, has discovered enormous amounts of ice very near the surface over much larger areas of the planet than we had imagined possible. I still don't understand quite why, but that's great because when humans go there, they're going to need to be able to get accessible water molecules for not just water drinking, to make rocket fuel from,

to make oxygen to breathe, and to grow plants with. We know so much more about Mars now, thanks to these wonderful instruments that we have sent there and our observations from Earth. But this planet has fascinated humans since even before good old Percival Lowell thought he saw those big canals. It's fascinating for the reason is, right now, in the period of August 2003, because it's so bright in the sky. This great big reddish object, ancient people knew that it wasn't a star, it was different, it was called a planet or a wanderer, and that it gets bright and then dim at times,

and changes, made it a very mysterious object from the very beginning. You mention how bright Mars is in the sky right now. It is an incredible sight. Is this especially exciting, do you think, for somebody who's been staring up at Mars, wondering about it and investigating it for quite a long time? Well, I'd like to say that this closest to 50,000 years is of tremendous importance to ground-based observers

other than the usual period of time, which is frightening around every 26 months, the fact is that it realistically isn't measurably or perceptibly brighter as seen by the naked eye or even through a telescope. The closeness is a very minor matter. But the phenomenon that we're seeing and which is called to attention by this is really quite striking. It's very large relatively in the sky with a telescope.

It's big enough you can see a lot more detail. So that pattern has always been very exciting to astronomers, and observational campaigns were adjusted for that. Most importantly, SPRIKE is close to us. When it's closer, it means that the rocket fuel required to get there is less. And so for planetary exploration with spacecraft, which is my bag, these periods of time when Mars and the Earth get very close together are extremely important to get big payloads there most efficiently. And that would explain why we now have five, count them, five spacecraft on their way. Yeah.

I think people knew it was going to be like that a long time ago and meant that for the same launch vehicle, you could carry more payload and do more at this time than you can at the opposite phase, which happens in between. You mentioned Mars Global Surveyor, Mars Odyssey, these amazing orbiters that actually have the power to find water ice under the surface of Mars. As far as I could tell from your biography, your first Mars mission that you were involved with was Mariner 4,

the flyby in 1965 that returned 22 somewhat grainy television pictures. You had a lot to do with that. Do you ever look back at those pictures? As a matter of fact, quite recently, because I gave a talk at a conference in Colorado, and the title was Mars, Land of Broken Paradigms. And the reason I choose that title is that it has fooled us so many times. First, the view from the telescope is first of all low, and then more refined scientific views.

And then Mariner 4 came in and returned not even 21 useful pictures or less than that. But among them were some that showed giant craters that looked like the moon. And what I was showing in this talk was exactly that. And that was the beginning of the first paradigm breaking. And then it's been repeated repeatedly by Mars since then. There was a good deal of disappointment, wasn't there? I mean, you say these constant surprises. There were a lot of disappointed people in 1965, even folks like Ray Bradbury. I might have been disappointed,

although I think he stayed pretty optimistic. Ray, of course, celebrating his birthday during this closest pass of Mars to Earth. Yeah, Ray, I knew him then, fortunately, or forgot to know him about that time. Ray is an optimist about humans and the Earth, and he's a fan of what's out there. But going ups and downs are really about the Earth and eventually about our going out from Earth to the planet, which he believes very deeply. The exciting thing about that 1965 flyby on July 15th, to be precise,

was that it, first of all, demonstrated the power of planetary exploration in a way that's hard to believe. That little probe that did that weighed 575 pounds. There are instruments that go on spacecraft now that weigh that much. And this was the first one that had a terribly difficult thing to do. But it made the big discoveries, and it demonstrated beyond the public to the scientists and the engineers that exploration is a very powerful thing.

Seek and ye shall find. We didn't know what we were going to find. We certainly didn't expect what we found. That's the message. You forget that these things are extensions of people. The real brains are us. These are our extensions. And so, ultimately, it is our brains

and with or lack of it, in terms of broken paradigms, that is a crucial thing. And I think that's an important point to get across. Intelligence is on the ground. Not too many years went by, and you had moved up to director of the Jet Propulsion Laboratory. You ran the place for, oh, about six years. Early in that tenure, you saw another incredible milestone in Mars exploration, the Viking landings.

Right. Getting back to this broken paradigm theme, the Mariner 4 cracked the idea that it was Earth-like, it had no magnetic field, the atmospheric pressure was about the same as it is on the Earth at 100,000 to 120,000 feet. It's hardly a

climate environment. And that was reinforced by the flights that went in 1969, two more flybys. But in 1971, the first orbiter went called Mariner 9, a very dramatic name, and that it discovered enormously different things, especially huge channels that had been carved by flooding probably several billion years ago, huge volcanoes, stacks of layers in the polar regions thatifying to climate fluctuations and maybe something like glacial processes. And so the attitude switched, that if there was water there then,

there could have been life there then, why isn't there water, or at least why isn't there life there now? And that led to a tremendous effort of the part of the United States to go to Mars and try to find life directly, detect it, the hardest job of all, and that was Viking. Let's talk more about Viking when we come back from a quick break. Our guest this week is Dr. Bruce Murray. He is Professor Emeritus now at the California Institute of Technology, has spent many, many

years there, was the Director of JPL, and continues to serve in the Planetary Society as the chairman of the board of directors. We'll be right back. This is Buzz Aldrin. When I walked on the moon, I knew it was just the beginning of humankind's great adventure in the solar system. That's why I'm a member of the Planetary Society, the world's largest space interest group. The Planetary Society is helping to explore Mars. We're tracking near-Earth asteroids and comets. We sponsor the search for life on other worlds, and we're building the first-ever solar sail.

You can learn about these adventures and exciting new discoveries from space exploration in The Planetary Report. The Planetary Report is the Society's full-color magazine. It's just one of many member benefits. You can learn more by calling 1-877-PLANETS. That's toll-free, 1-877-752-6387. And you can catch up on space exploration news and developments at our exciting and informative website, planetarysociety.org.

The Planetary Society, exploring new worlds. Our guest this week on Planetary Radio, Dr. Bruce Murray, Professor Emeritus from Caltech, former Director of JPL, Chairman of the Board of Directors of the Planetary Society. Bruce, when we left, we were kind of leading up to the Viking missions. You talked about Mariner 9, which reversed the paradigm once again, found that tantalizing evidence of water. And so you were there when Viking went to Mars, apparently to look for life. What did it find?

It had an extraordinary discovery, because the way it worked, it had a very elaborate one with a big arm and it reached out, scooped up samples. The samples were dropped into an internal laboratory that was maintained at atmospheric pressure and temperature and enormously expensive and elaborate. And there were two parts to this laboratory. One part was the standard test for life on Earth, which is you put whatever you think may have bugs in it, microbes, in a Petri dish with some nutrient of some kind and see if anything grows. And if it grows, that's one of the fundamental definitions of life is met.

And so it was capable of doing that not just with Earth-like nutrients but with more fundamental ones made up of amino acids and things like this. The other experiment, which was done subsequently, was to analyze a soil with the most sophisticated instruments available to look for organic molecules in the soil. The important thing to remember there is that even on the moon there are organic molecules because meteorites falling in have some organic material, which ends up in the lunar soil. The important thing to remember there is that even on the moon, there are organic molecules because meteorites falling in have some organic material, which ends up in the lunar soil as much as 1%. So you would expect to find that on Mars,

and you would expect hopefully to find stuff that was indigently produced by Martian life. So the great day came, and I was the director of JPL, following it fairly closely because the significance of this were profound in terms of public interest. And so the soil was dropped into the first set of tests, the ones that were trying to grow something, and they expected to see small increases in carbon dioxide or oxygen, depending on the reaction. Instead, they got huge reactions. It almost overpowered the instrument. And so, my gosh, is this place crawling with life?

What's going on? And so the cooler heads prevailed and said, no, this is not life. This is chemical reactions of some kind going. And indeed, that was the case. What they were seeing was the fact that the Martian soil had not seen any water or moisture, most likely for several billion years. So that unlike Earth soil, or everywhere on Earth sees some moisture or water, sometimes pretty frequently, even the driest deserts. And in that condition, and under the particular circumstances of Mars, the soil had become super-oxidizing or hyper-oxidizing.

It was the equivalent of hydrogen peroxide, which you can use to dye your hair or dress wounds. And so any organic material that you put into, even water, gets broken down as molecules and creates the gas. So what we're seeing was the fact that Mars is an enormously reactive surface, and it's particularly reactive against any unfortunate water or organic molecules that gets there. Well, the other test, which was to look directly for organic molecules, at least those brought in by meteorites, was being run,

and its results came out also in a stunning fashion. There were no organic molecules detected. The surface of Mars is sterile to a very high degree, and that this process I mentioned where the sunlight coming in acts on the soil in a way that produces its hyperoxidation is self-sterilizing, at least in the upper part of the soil where they sample. So from a high of, we're expecting to find microbes here, willing to spend $2 billion of 1970s money to try to find this,

to suddenly discovering that not only were none found, but the planet seemed to be self-sterilizing in its upper layers. That was a terrific shock. And so the paradigm switched again. Optimism was replaced by pessimism about life. And to a large extent, a fairly long hiatus in Mars exploration by the United States followed. Did you or your good friend and colleague, co-founder of the Planetary Society, Carl Sagan, did you actually lose hope? Well, I was never hoping for life.

Carl was. I'm a geologist. To me, it's a fascinating place, with or without life, and that in any case, I'm strongly driven by observations. And it's an enormously interesting place, as we're still finding. That's the point of the Land of Broken Paradigms discussion, is that it's continually surprising us. And so I was not up or down.

I was excited by what we'd learned and what's going on. I think Carl was disappointed because he had the view, which in the long run may be right, that life sort of has to be everywhere. There are many scientists who've come to have this view. A naturally occurring phenomenon, as natural as the formation of planets.

Some people would think even more so that it's an essential form of process in the universe itself. It ultimately has to get to self-awareness in order that there's an audience for all the activities of it. So yeah, this is a very profound subject, but I would have to say less imaginative about that. I was focused on trying to understand what was there.

But Carl and I together made a good team because he was the theorist, the dreamer, what might be, and I was much more what is, what couldn't be, and so forth. And the tension between us was very productive. But moving on then, there was this long hiatus, which also coincided with the fact that the development of the space shuttle had been mandated by NASA at the expense of launch vehicles to go directly to the planets on their own. With a few exceptions, nothing much happened in any planetary exploration

until Magellan went to Venus in the 1980s, late 80s, and not back to Mars again until the early 1990s. But with that return to Mars, have we seen, it certainly sounds like, we have seen yet another reversal of that paradigm. Exactly. And that includes the fact that there is an enormously larger amount of ice in the near surface layers on Mars than anybody had dreamed, either the pessimist or the optimist. Nobody had, and we still don't have a good explanation for it.

That's evidence that it is a more habitable planet for microbes. They can figure out how to do that, but especially if it's a more habitable planet for us, because that's what we need. We need extractable water, extractable ice, in order for human activities there to flourish in the future. Unfortunately, we have only a couple of minutes left. I think you must be looking forward with great anticipation to these two Mars exploration rovers, Spirit and Opportunity.

Yes. They are equipped with many different kinds of instruments. There's an enormous amount of effort going into trying to understand how to use them effectively, and they have the capability of really telling us a lot about what's in that soil, maybe getting some hints of this ice, whatever depth it is below them. I hope so, although they were not designed. They don't have drills. They weren't designed for that mission in that regard.

So this is going to be very exciting. It's going to be publicly very interesting because the rovers will be moving in a series of increments, and therefore the scene will change, and it will be clearly a chance of the public riding along, so to speak, on the backs of the explorers through all their cameras and participating directly in this wonderful process of exploration.

And even before that, in fact, only about a week from now, will you be helping Ray Bradbury to celebrate his birthday and this very close passage to the red planet? Most assuredly. My wife and I are looking forward very much to seeing him, giving him a big hug, and then going on up to Mount Wilson Observatory afterwards to look at Mars with a 16-inch telescope and other telescopes up there. I've seen Mars at the same period of time called Opposition, as early as 1960,

and it's an overwhelming experience. I likened it once to seeing a wonderful Japanese lantern glowing up there in the telescope with these soft colors, and you should be able to see the northern polar cap. It would be fantastic. Well, Bruce, I think Carl would be proud of you for that last statement. Our guest has been Dr. Bruce Murray, professor emeritus from Caltech, former head of the Jet Propulsion Laboratory, the chairman of the board of the Planetary Society,

and still someone who gets very excited about looking out there and wondering and trying to find out what's going on. Bruce, I'm sure we will have you on again. Thanks for joining us today. My pleasure. I'm Emily Lakdawalla, back with Q&A. The early sun blew away the terrestrial planet's original atmospheres, but luckily for life on Earth and water on Mars,

all of these planets developed secondary atmospheres. The primordial atmosphere was made of light gases like hydrogen, helium, water, methane, and ammonia, leftovers from the formation of the solar system. The secondary atmospheres developed as a result of a process called outgassing, in which volcanic activity brings light elements from the interior of a planet to the surface. Volcanic gases include water, carbon dioxide, and sulfur compounds. In addition, millions of comets traveling from the outer solar system have impacted the terrestrial planets, contributing their own load of water and organic materials. With thick atmospheres of gases that trap solar heat, the large terrestrial planets, Venus and Earth, control their own surface temperatures.

On Earth, this means that changes in the sun's temperature over time have not endangered the existence of our oceans. But the smaller planets, Mercury and Mars, could not hang on to their atmospheres. Mars may once have had a secondary atmosphere of carbon dioxide and water that was thick enough for liquid water to survive on the surface, but that atmosphere is long gone, leaving it once again a nearly naked ball of rock. Got a question about the universe?

Send it to us at planetaryradio at planetary.org. And now, here's Matt with more Planetary Radio. Time for What's Up with Bruce Betts, live and in person from Planetary Society headquarters. Welcome back, Bruce. Hi there. Good to be back. I'm feeling excitable today with a piece of tortilla chip caught in my throat. Oh, well, that's good for radio. Yes, indeed.

Well, while Bruce recovers, oh, he has. It's a miraculous recovery. What do you got for us? We've got what to look for in the night sky, and I'm just going to be redundant for weeks. You might as well be prepared for it. Mars, go out and look at Mars. I'm telling you, as your friend, as the radio host you never want to meet, go out and see Mars, or you may meet me. You're just trying to scare away the crazies who've been writing to us.

Please let's not call them crazy on the air. I'm sorry. So anyway, Mars, it will rise around sunset. It will set around sunrise. And you can see it in the east in the evening, in the south in the middle of the night, and in the west before dawn. And we are rapidly approaching August 27th when it will be brighter than it has been in the west before dawn. And we are rapidly approaching August 27th when it will be brighter than it has been in the history of the human species. So get out there. It's gorgeous. It's naked eye. It's reddish orange. It's the brightest thing out there besides the moon. You can't miss it.

Incredible. And if you have a small telescope available, you know, your neighbor's telescope, get them to take it out because it's going to be even more spectacular. Exactly. Even in a fairly mediocre small telescope, you can probably make out the south polar cap, which you can see on the disk of Mars. And if you're looking for other telescopes and events you can go to, go to planetary.org slash MarsWatch2003, where we have a list of events around the world that are part of the Planetary Society's MarsWatch. How about this week in space history?

We had two very important launches on August 20th. One in 1975, one two years later in 77. Viking 1 launched in 75. Voyager 2 in 77. Voyager 2, the only spacecraft to visit all four outer planets. Speaking of random space fact. Olympus Mons, tallest mountain in the solar system. It is on Mars. It is almost three times higher than Mount Everest.

And it's a spiffy keen place that would be as wide as the state of Arizona. How's that? That was great. I'm just a little slow on the pickup today. Slow on the return. I'm sorry. little slow on the pickup today, slow on the return. I'm sorry. But, yeah, you know, the only thing better would be to climb it. That's still something I hope to do someday. But anyway, who cares? Or ski it.

Who cares? We're moving on to trivia contest rather than Matt's planetary desires. Last week, the question, as I read it on the air was what is the Torini scale? It was just all a test to see how much attention you're paying because I know it was obvious to all the listeners that I meant Torino scale, not Torini. But we did get definitions of both, I believe. And how did we do with the listeners?

Absolutely fab. Fabulous. We got a lot of very humorous people. A lot of people were too polite to point it out. They actually, in their answer, put Torino, but they realized that it would probably not help their prize-winning opportunity if they pointed out your test. I almost said error. Your test of them. But we did have a few who had a lot of fun with it, and our winner this week was actually one of those. Christopher Reagan, congratulations. You get this week's Mars 3D poster with the spiffy cool 3D glasses. Christopher hails from not far from us at all, Los Angeles, California.

Haven't had a local in a while. And he got it right. The Torino scale is a novel way to teach school children about problems associated with cataclysmic collisions. Well, anyway, it's really a scale from 1 to 10. And I'll let you provide the details, but he also provided us with a definition of your Torini scale, which is a method of estimating the water displacement potential of opera singers. You know, even I didn't know that.

Well, I'm sorry for the confusion then. I didn't realize there actually was a Torino scale out there in the opera world. The Torino scale is a way to try to assess the asteroid and comet impact potential of a given prediction. So when one calculates that one of these objects might be on its way to Earth, it gives an idea from 0 to 10. 0, you're not going to have a collision. To ten, say goodbye. And many things in between to try to give some way to convey out to the public and the press. And as Christopher Reagan said to the children of the world, what the risk and danger is.

We had a lot of other great entries. We don't have time to read them today, but keep the funny stuff coming, folks. We enjoy them. We really do. How about our next contest? Ah, our next contest is going to be a little boring after the Torini-Torino scale, but maybe I'll mispronounce something.

Who was the second woman in space? The second woman in space? The second woman. Not the first, not the third. Ladies and gentlemen, boys and girls, we're looking for the second woman in space. And for all those folks who want to write in with their factual but humorous answer, go to planetary.org and follow the links to Planetary Radio, and there you will find out how to enter.

Remember, get them to us by Thursday of this week, Thursday around noon Pacific time, earlier if you can manage it. We'd appreciate that. And you'll find everything at planetary.org. So, Bruce, we're out of time. That makes me so sad. But go out, look up in the night sky,

and think about why you can't see birds flying over at night or why it's so darn hard. Thank you, and good night. Bruce Betts is the director of projects for the Planetary Society. He joins us each week right here on What's Up. Join us next time for a special birthday tribute to author, poet, and eternal optimist Ray Bradbury. Have a great week.