Planetary Radio: Space Exploration, Astronomy and Science - The Depths of Space: A New Book About the Pioneer Planetary Probes

Episode Date: November 29, 2004

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Naked Pioneers headed to the stars, this week on Planetary Radio. Hi everyone and welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan. Pioneer 10 was the first human-built envoy to Jupiter, and the first to pass out of our solar system. We'll talk with the author of a new book about the plucky probe and its sister ships, and of course about those revealing plaques they are delivering to E.T. Something tells me what's up is happening at the zoo, where Bruce Betts will offer up a new space trivia contest, and Emily will provide a breath of fresh, though thin, Martian air right after these headlines.

IBM has announced something called the World Community Grid. The effort is intended to use millions of personal computers to provide a gigantic distributed computing platform for scientific projects. to provide a gigantic distributed computing platform for scientific projects. If this sounds familiar to you SETI at home participants, it's for good reason. The Search for Extraterrestrial Intelligence project paved the way for this new effort, virtually inventing grid computing. We'll have more on this story next week. The new Spitzer Space Telescope orbiting the Earth is returning data that may help distant Pluto keep its status as a planet.

Other recently discovered objects that are even farther from the sun seem to be somewhat smaller than first thought. And NASA has just concluded an international workshop. The Washington session considered opportunities and possible collaborations in missions that are part of the U.S. vision for space exploration. You can read much more about these and other stories at planetary.org. I'll be back with author Mark Wolverton right after Emily. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, what happened to Mars's ancient atmosphere? Most, but not all, scientists agree that during Mars's early history, the atmosphere was much thicker than it is today. This argument is commonly based on the observation of dry riverbeds

on the oldest Martian terrain. At some point, water ran freely on the Martian surface, but today the low atmospheric pressure precludes the possibility. Where did all that gas go? One possible place is the rocks themselves. Carbon dioxide can dissolve in water and combine with metal ions to form carbonate minerals. This is what happened to Earth's original supply of carbon dioxide, which is now locked into huge deposits of carbonate rocks such as limestone.

But many scientists believe that the primordial atmosphere managed to escape Mars entirely. Stay tuned to Planetary Radio to find out how. Journalist Mark Wolverton started out writing magazine articles about the pioneer series of spacecraft. He soon realized, though, that the dramatic and sometimes controversial story of these trailblazing probes was worthy of a book. So he wrote one. The Depths of Space is subtitled

The Story of the Pioneer Planetary Probes. Mark Wolverton, thanks very much for joining us on Planetary Radio. Thank you, Matt. If we can, I want to start with a line from the very first chapter of your book and preface that by saying you make reference a number of times Thank you, Matt. Given considering and comparing the political and budgetary realities of Pioneer's time with those of the Golden Era, the Pioneer project, dollar for dollar, spacecraft for spacecraft, and mission for mission, is still the most efficient, cost-effective, longest-lived, and most successful series of deep space probes ever created.

That is a pretty strong statement. Well, I think really when you look at the overall Pioneer project and consider the number of firsts that it gave us for the money, and even translating it into current dollars, and consider the fact that the Pioneer program really had no major failures. When I talked to a lot of the Pioneer veterans and people who had worked on the project, some of them said, well, we were doing this faster, better, cheaper, before Dan Golden came up with this snappy phrase for it.

But we did it the right way, because you can do any two of those things and get away with it. If you try to do all three, you can get into trouble. I think the Pioneer Program just demonstrated how you can do all of those things and still have a very successful program. And we should probably mention that when we talk about the Pioneer series, in your book you primarily are dealing with Pioneer 6 on through the Pioneer Venus orbiter, actually. Right. The actual program, the Pioneer program or project, started with Pioneer 6. But actually within the Pioneer program, it gets even more confusing because they used

letters to distinguish each mission before they were launched, starting with A. So Pioneer 6 is actually also Pioneer A until it was launched, and Pioneer 7 was Pioneer B and so on. And this was because NASA got a little bit worried about, you know, let's not give them a number until they're actually up there doing the job. Right. That's official. And I know that from Pioneer 6 on, another thing that united these probes was where they came from, which is a key part of your story, the Ames Research Center in Northern California.

Right. It was the first major space program that Ames had done at that time. Before then, all the unmanned probes were launched by the Jet Propulsion Laboratory, as really they still are, mostly. But at that time, NASA was kind of looking for another center within NASA to handle some more of the unmanned program, take a little bit of it away from JPL and kind of spread it out a bit. And the people at NASA Ames campaigned for this, and they managed to get the nod from NASA headquarters. There was no shortage of heroes in this story

of the Pioneer series, but it does seem like if you had to pick one person who really should most be identified with these successes, it's this fellow Charlie Hall. Oh, absolutely. He was the project manager from the very beginning until the end. And he was a guy who is a very strong leader, a very charismatic leader. As I interviewed various people that had worked under him on the project,

I was struck by how universally admired and respected he was. I don't think I've ever heard of any other human being who everybody just really strongly respected and remembered. And everyone had at least one story about Charlie Hall. He's one of those guys that people just tell these war stories about or legends about. I think he really was the key factor behind the success of the Pioneer program. When you look at the Pioneers, the whole series that he worked on, but in particular the big stars, Pioneer 10 and 11, they really were kept very simple.

I mean, these weren't really smart spacecraft, but I guess that was part of their genius. It really was. That's one reason why they lasted much, much longer than they had ever been designed for. Pioneer 10 and 11 were really just designed to get as far as Jupiter. They were only supposed to last several years, and they both kept operating. Well, Pioneer 10, we lost contact with that last year, which was over 30 years after it was launched from Earth. And that certainly was the key philosophy, just keep it simple.

Charlie Hall always insisted that if you're not sure if something works or not, it's not going to go into spacecraft. We want them to be very reliable, because the more complicated it is, the more things there are that can go wrong. And that even went into something as fundamental as the stabilization of the spacecraft. With unmanned spacecraft, there are basically two ways you can maneuver them. One is to what they call three-axis stabilization,

which is basically you have thrusters that will maneuver it around the pitch, yaw, and roll axes. And another is just to have them spinning like a top, as most satellites do and the Pioneer space probes did. And that's very simple because all you do is when you launch it, you set it spinning, and then because it's in space, there's nothing that slows it down. It just keeps spinning, always pointed in the same direction. Of course, you do have thrusters on it to tweak the trajectory a little bit here and there.

But it's a much simpler and much more basic way of stabilizing a spacecraft. And that's one of the hallmarks of the Pioneer spacecraft. All of them are spin-stabilized, which is something that is almost unheard of now with space probes. All the more sophisticated ones that have followed, such as Voyager and Galileo and Cassini, they're all three-axis stabilized. Meaning they have lots of thrusters and they have to constantly adjust. Right, and it also means they're more expensive and they're heavier and more complicated. We're talking with Mark Wolverton. He has just written The Depths of Space, the story of the pioneer planetary probes.

And Mark, as always happens when I know I'm an interviewing author and I read that author's book, and I like the book, the book is in front of me, and it is full of little green Post-it notes that we are never going to get to, Olive, in the little time we have left. But if we can, after we take a break, I'd like to spend the rest of the time mostly talking about the two big stars of the Pioneer series, Pioneer 10 and 11. Okay. We'll be right back with Mark Wolverton after this message. This is Buzz Aldrin. Okay. We'll be right 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. Welcome back to Planetary Radio, where this week's special guest is Mark Wolverton.

He has written The Depths of Space, the story of the pioneer planetary probes. It is available from Joseph Henry Press. And as promised, Mark, I want to talk about Pioneers 10 and 11. It's a shame to say, but you do even talk in the book about how these pioneers, in every sense of the word, their fame and their accomplishments have almost been left in the background by the big expensive probes that have followed. But they really were pathfinders. They really were.

They were the first. Pioneer 10 was the first to go beyond Mars. Before 1972, no one, including the Soviets, had launched any spacecraft that far out. And, of course, many of the craft that we had sent to Mars and to Venus had been lost for various reasons. And one of the major contributions of Pioneer was it really opened up the outer solar system. Before Pioneer, before Pioneer 10 specifically, we didn't even know if we would ever be able to go beyond Mars because of the asteroid belt and the radiation environment, if we'd be able to even communicate with spacecraft.

So really, without the Pioneer 10 and 11 and the example, the model that they provided and what they accomplished, everything else that followed, including Voyager, would not have been possible. These spacecraft were not only fairly simple in their design, simple to increase reliability, but they were dwarfed by the Voyagers and Galileo and Cassini. Oh, yeah. They're very small. Pioneer 10 and 11 were identical spacecraft, and we're talking the main antenna was only 9 feet in diameter, which was the biggest part of the spacecraft.

They had three booms that went out from them, but really the main bulk of the spacecraft was about the size of a very small, compact car. So compare that to Cassini, which is about the size of a bus, I believe. Yes. One of the innovations, and was almost in this out of step with the rest of the design on these spacecraft, is that they realized, Charlie Hall and his crew, that they were going to be too far from the sun for solar cells. Right. They used Pioneer 10 and 11, each carried four RTGs,

which is short for radioisotope thermoelectric generators. And what those are are basically devices that use a small amount of plutonium-238, and they generate electricity from the heat, from the decay of the plutonium. The solar cells would have had to be so big and so delicate that this would have been impractical. But the RTGs proved to be quite reliable. They had been used in some Earth-orbiting satellites before then, but this was the first time they'd really been used on a deep space mission. There was a lot of question as to how long they would last, if they would be able to

operate and generate power for so long. And, of course, they operated for, well, about 30 years or so. Yeah. As you said, I mean, we just lost touch with Pioneer 10 after, I think, 31 years, 7.5 billion miles. That's pretty good mileage. Over 8 billion. RTGs have come to gain a little notoriety to be a little controversial, especially since then.

But if you had to point to something controversial on Pioneers 10 and 11, it probably had a lot to do with something that one of the Planetary Society founders, Dr. Carl Sagan, had something to do with, and that, of course, was the naked people. Right, on the plaque. Both Pioneer 10 and 11 carry a 6-by-9-inch aluminum gold anodized plaque. There was a science writer named Eric Burgess who initially was seeing the testing of Pioneer 10 at TRW, which is the company that built the spacecraft.

And he realized these were going to be the first spacecraft outside of the solar system, and maybe we should think about that and put some kind of message on it. And he went to Carl Sagan. Carl Sagan loved the idea, and Sagan went to Frank Drake, who, of course, is a pioneer of the search for extraterrestrial intelligence, radio astronomer. And they took it to NASA, and they came up with this idea of the plaque and putting a message on there. On the plaque, there are scientific information about the hydrogen atom, a schematic diagram of the pioneer spacecraft, a little image of the solar system.

There's a map that plots our position in the galaxy, and there are, of course, the two naked human figures. And, of course, the reason for that was that, well, if we're going to show aliens what humans look like, our natural state is nudity, therefore, the figure should be nude. You talk about some of the press coverage of this and some of the letters that the team received and one political cartoon that apparently

showed a couple of very human-looking aliens looking at the plaque and saying, well, apparently Earthlings are a lot like us, but they don't wear clothing. Right. And there is another one, too, that I like, which shows two little green men, and there are a couple of scientists that are standing there greeting them,

and one scientist says to the other that, he says, well, they say they got our message on the Pioneer spacecraft, and they came to see the naked women. You know, I remember I was a teenager at the time, and so I was maybe appropriately embarrassed as a slightly shy teenager, but also being in awe, and I still feel that now, because of what this represented, in addition to the science returned by these spacecraft, that here was humankind reaching out into the galaxy, sort of saying, you know, we were here, or we are here. Right, exactly.

That's what I find so compelling about the Pioneer craft, especially 10 and 11, which really were the first to go out of the solar system. And, of course, they're out there now. Even though we're not in touch with them anymore, they will be going out there indefinitely, and they may be around much longer than Earth is. And, of course, with this message, the plaque, which, of course, Carl Sagan made the observation that it's not only a message from Earth,

it's a message to Earth, just an art, not only in showing how we reacted to this idea of the plaque, but also it helped to bring back the idea to the population at large that we can communicate with extraterrestrials if they're out there. And there's a lot more out there that we can do and that we can experience than just our Earth-bound concerns. Talk a little bit about the science that they returned, the discoveries that they made, not only at Jupiter,

but Pioneer 11, which was able to reach Saturn. Right. Well, starting with Pioneer 6 through 11, which was able to reach Saturn. Right. Well, starting with Pioneer 6 through 9, which were solar orbiting craft, they were all placed in orbits around the sun at about the same distance as Earth. They gave us our first really global picture of the solar wind and solar activity, solar storms. That was quite valuable at the time. That's something that had not been done.

activity, solar storms. That was quite valuable at the time. That's something that had not been done. Pioneer 10 was the first, through the asteroid belt, the first to Jupiter. Gave us our very first close-up look at that planet. It showed conclusively that the Great Red Spot is a giant storm in Jupiter's atmosphere. Gave us our first look at the radiation environment around Jupiter. It gave us our first indication that Jupiter has a ring, discovered some new moons. Pioneer 11, which followed it to Jupiter a year later,

kind of filled in the gaps that Pioneer 10 had left. And then, of course, they realized that because Pioneer 11 took a somewhat different trajectory past Jupiter, they could actually use that and tweak the trajectory a little bit, use Jupiter to whip the spacecraft around and send it on to Saturn, which of course was not part of the original mission plan, both Pioneer 10 and 11. The original mission objective was just to get to Jupiter. With Saturn, we got another planet in our pocket for the price of one, really. And it also demonstrated that it was possible for a spacecraft to cross the ring plane at Saturn, which, again, is something that was a complete unknown before then.

And that is something that reverberates to our own day, I can tell you, because as listeners to this show know, we were covering the orbital insertion of Cassini last summer. I was at JPL. There was remarkably little concern by the scientists there when it came time for that huge spacecraft to cross the ring plane. Why? Because they knew Pioneer had done it and the Voyager spacecraft as well. But basically, they'd been able to get over the fear because Pioneer 11 had forged the path so many years before. Exactly. And that, of course, was quite in contrast to the fear that was there when Pioneer 11 first went there,

because there was some great concern about going through the ring plane and how far out the ring material would go and whether the spacecraft would hit something. Mark Wolverton, I wish we had more time. There is so much more to this story. All I can do is recommend to people that they get a copy of The Depths of Space, the story of the Pioneer Planetary Probes, the new book from Mark Wilberton, which traces the history of the Pioneer series of interplanetary spacecraft. It is available from Joseph Henry Press. It is listed

on Amazon. You can get there directly, or there is a link to Amazon from the Planetary.org website. We will have other links on the Planetary Society website, right on the page where you can listen to this radio show. Mark, again, thanks very much for joining us for this conversation about Pioneer. Thank you, Matt. And we'll be right back

with more of Planetary Radio, including Bruce Betts and What's Up, after this return visit from Emily. I'm Emily Lakdawalla, back with Q&A about what happened to Mars' atmosphere. Much of Mars' gas may have escaped the planet for good. Repeated impacts of asteroids early in its history could possibly have driven off a volume of gas equal to 100 times the present volume of Mars' atmosphere. A vital clue is the relative amounts of the isotopes of the gases that we can measure today.

The isotopes of a given element have the same number of protons and electrons, but different numbers of neutrons. Additional neutrons increase the mass of an atom without changing its chemical properties. Ordinary hydrogen has one proton and no neutrons and thus has only half the mass of heavy hydrogen, which has one proton and one neutron. Heavy hydrogen, also known as deuterium, does not escape from Mars as readily as light hydrogen, so escape of hydrogen from Mars' atmosphere should leave behind lots more deuterium than you would expect. In fact, we find that deuterium is about six times more abundant on Mars than on Earth, indicating that a large amount of hydrogen

has escaped from Mars forever, leaving the present planet dry and without much atmosphere. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now, here's Matt with more Planetary Radio. Well, Christmas carolers in the background, it must be time for What's Up? Live from the Los Angeles Zoo? Indeed, Matt. We're trying to mix as many things together as possible, keep everyone out there on their toes. So we're at the Los Angeles Zoo, we're researching astrobiological implication of gazelle. So Bruce, Bruce Betts, the Director of Projects for the Planetary Society, what's up? Well, in the night sky, you can look for stars, but you can also see a lovely planet.

Saturn rises around 8 or 9 p.m., rising in the east. You can see it in the constellation Gemini near Castor and Pollux. In the pre-dawn sky, you can still... They really like Castor and Pollux, I guess. Right, I forgot that part. Okay, so in the pre-dawn sky, go out there, and you can see Venus still looking extremely bright, looking like the brightest star-like object in the pre-dawn sky.

And to its upper right, you will see Jupiter also looking extremely bright. And to Venus' lower left, you may be able to catch Mars, much dimmer and sort of orangish-red. I like ornish. Ornish is good, too. Yes. I think I'll be fixing an ornish dressing this year. All right, let's move on to Random

Space Fact! I feel badly interrupting the singing. Thermal inertia is a parameter used by planetary scientists. What the heck does this mean? It's a resistance to heating, resistance to temperature changes. So if you go out, rocks have high thermal inertia. They will heat more slowly in the day, they'll feel cold,

and at night they'll cool more slowly, so they'll feel warm. By looking at the temperature of a surface, you can determine how many rocks and sand and dust and silly things like that are there. It's one of the things I used to do recreationally. Recreationally. I don't doubt it for a moment. Okay. We go on to trivia?

On to trivia contest. We asked you before, who discovered Pluto's moon, Charon? Please, tell us, Matt. How'd we do? You know what? I have to admit, it's not entirely random this time. Oh, my gosh. The sanctity of the show. I know, I know. We're going to hear from the FTC or somebody about this violation.

I knew nothing about this. Yeah, Bruce's, it's entirely my responsibility. And that is why our winner this week is Ian Scales. Ian Scales, who hails... You know why I chose him? Why? Not because he said, come on, guys, let's have an EU winner, but because of the name of his town

and even his street. Ian, who lives on Whopping High Street in Whopping, London. Wow, nice. I figured he had to be a winner. Besides which, he got it right. He said that Pluto's moon, Charonon was discovered in 1978 by James Christie, and I assume he was correct. That is indeed correct.

We had entries like, oh, a whole bunch of entries from all over the world, and a lot of people who explained that James Christie named Charon that in part because of his wife's name. I guess he couldn't call the moon Charlene, so he came up with the next best mythological thing. And then other people who said that Tombaugh named Pluto, around which Charon revolves, named it Pluto in part because of Percival Lowell, the astronomer who did all sorts of neat stuff in the solar system. Actually, the symbol for Pluto, if you look at it, looks like a P and an L put together. We should mention Sharon, who I had a terrible trouble pronouncing,

so I appreciate all of you trying to help me, was mythologically the person who escorted the dead across the River Styx to the hangout of Pluto. Well, Ian, you will be getting that Planetary Radio t-shirt. He even let us know that he needs an extra large. Now the world knows. Bruce, I bet you have something else for us for the coming couple of weeks. I do indeed, if you want to win a Planetary Radio t-shirt. Answer the following question.

We're talking about Mercury. Tell me the relationship between mercury's year and its day mercury has a particular so-called orbital resonance just like the moon is in a one-to-one synchronous locked rotation oh i love using those words around the earth so it always faces one side towards the earth well mercury is also in a resonance but it's not one-to-one as was originally thought with the Sun. It's closer to the Sun, so there is some tidal effects, but it's not one-to-one. Tell me what it is, which is basically the relationship between Mercury's day and its year.

To enter this glorious contest, go to planetary.org slash radio and learn how to send email to us and enter this, up until now, random contest. And, Bruce, I'm going to ask them to go there to get the deadline as well, because we have two other announcements we have to make. Do you remember the question you asked last week about getting the new title for the NASA administrator? Yes, indeed. Trying to elicit some creative responses. And hopefully something that would make the judges, that is you and I, laugh a little

bit. We haven't gotten very many. So we're going to extend the deadline. Instead of the deadline being, what would it be, the 29th at noon, Monday the 29th, let's make it December 2nd. We'll give them a few more days. December 2nd at noon Pacific time. And if you could just reiterate that contest question one more time briefly.

The head of NASA is called the NASA Administrator. I personally think he should have a better title. So please send us what you think the head of NASA should be called, what his title should be. Enter. Make us laugh. Entertain us. Yeah, ideally, give us something that can be repeated. Bruce, we also, before we say goodbye, we want to welcome a whole bunch of new listeners. Yay! We also, before we say goodbye, we want to welcome a whole bunch of new listeners.

Yay! KCHO 91.7 in Chico and its sister station KFPR 88.9 in Redding, California. And actually, much more than that, because they are all over Northern California, they call themselves North State Public Radio, and this is the very first planetary radio to air on North State Public Radio. Yay! Welcome, everyone. I was a Central Valley guy myself growing up in Sacramento, so Northern California near and dear to my heart. We're done. We're out of time.

All right, everyone, look up in the night sky and think about caroling marine mammals. Thank you, and good night. And that was Bruce Betts, the director of projects for the Planetary Society, coming to you live, on tape, from the Los Angeles Zoo. And the hurry, hurry on his way So he's just fine Coming to you live, on tape, from the Los Angeles Zoo. By the way, that lovely quartet of carolers at the Los Angeles Zoo calls itself a Little Dickens.

We're a little late. I hope you'll join us again next time for a conversation with SETI at Home's David Anderson. Have a great week, everyone.