Planetary Radio: Space Exploration, Astronomy and Science - Charley Kohlhase: Engineer, Artist, Cassini Mission Designer

Episode Date: May 3, 2004

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His art and engineering are taking us to Saturn. Charlie Colhaze is on Planetary Radio. Hi everyone and welcome back. I'm Matt Kaplan. The spacecraft called Cassini is closing in on Saturn after more than six years in space. Today we'll talk with the man who was the mission's designer. Bruce Betts will give us a solar system special event update in What's Up, along with his latest trivia contest. First, though, let's go to Emily, who reminds us that, like people,

some planets are denser than others. I'll be right back with Charlie Colhaze. Planets are denser than others. I'll be right back with Charlie Colhaze. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, I read that Jupiter has an Earth-sized core of ice and rock, but what evidence do we have for thinking that Jupiter is mostly atmosphere? How do we know it's not really a giant planet of rock?

It's true that the interior of Jupiter, and indeed all of the rest of the planets and moons in the solar system, is not directly visible to our science instruments. But just a few measurements can yield a ton of clues to the mysterious interiors of the planets. The first important fact scientists learned about planetary interiors was their masses. Isaac Newton was able to estimate the masses of the known planets by combining his insights into forces and motion with Johannes Kepler's laws about the motions of the planets. He proved that the gravitational forces acting between the sun

and the planets are directly proportional to the masses of the planets. From calculations like these, you can learn that Venus has just about the same mass as Earth, but Jupiter is over 300 times as big. But this technique doesn't tell us what the mass is made of. To learn more, stay tuned to Planetary Radio. Jolly Cole Hayes joined the Cassini team 25 years ago and was soon balancing thousands of factors to lay out a path to Saturn. The giant probe has followed that path perfectly and is already returning spectacular data from the ringed planet.

Planetary Society members are reading Charlie's article about the mission in the current issue of its magazine, The Planetary Report. in the current issue of its magazine, The Planetary Report. We recently got together to talk about Cassini, but you'd be crazy to talk to Charlie about just one topic. He is as much artist as engineer and has spent decades exploring and creating art through photography, computer-generated imagery, and even the trajectories of the spacecraft he has worked on. And he worked on many during his long career at the Jet Propulsion Lab.

Charlie, how long were you with JPL? Started there in 1959, so that's a long time. That's like 45 years ago. Although I actually retired in 98, but I'm back consulting two days a week now for both the Mars program and for a mission called JIMO, which is to go back to Jupiter with a huge spacecraft, orbit the icy moons, finally orbiting Europa. We hope to talk about GEMO real soon on this program because it's incredibly exciting.

You used that word retired. I didn't think that was a word you would ever apply to yourself. Well, it isn't. I mean, I'm a carpe diem person. I kind of love everything. I love art and science and education and protecting the environment, and on it goes. And so I tend to get up when the first rays of sun come through the bedroom window and then crash at 10 at night. And, in fact, I lost a $100 bet on the retirement now that I think about it with Bill O'Neill, who was the Galileo project manager.

Yeah. I said, oh, Bill, I'll be retired by a certain date. And he says, Cole, you'll never retire. I said, okay, let's put $100 on it. And I lost. Have you paid up? Yeah, I paid up. We talked a little bit about the fact that you bring this combination of science and art

and engineering as well, applied science, to pretty much everything that you do. You wanted to be an architect early on. That's true. I had an uncle who was a well-known photographer whose photographs actually made the Smoky Mountains into a national park for the Congress. But I had a great-grandfather that was sort of like a da Vinci kind of person. He was an architect, artist, engineer for the city, musician, I mean, philosopher, on and on it went. And when I visited my grandmother's house in Tennessee,

I would see all of his paintings. And as a little boy, I knew him before he passed away. And I think that area put the art into the blood, so to speak. You know, art's supposed to be a right brain sort of a thing. But at the same time, I was reading, oh, George Gamow and Asimov and people like that and getting interested in science fiction. Now, if you're going to ever carry out the dreams of science fiction, you really need an education. You need to understand math and physics and vector analysis and all those things. And so I wound up sort of left-brain oriented towards a career

and right-brain dreamer artist sort of person. I actually love combining the two. A lot of times you will see close-up photography on magazine covers, like on the cover of Science magazine. By the way, JPL just a week ago has their first artist in residence. No kidding? Yeah, young man named Daniel Goods. He was valedictorian from the Art Center College for Design when he graduated. Some of the close-up photography of anything from oil slicks to computer chips or

what have you, if you go in close enough, it becomes art when you look at it. I'll give you another example, something that we've been trading around here in animation that's out on the web, which is good science. It is an accurate scientific simulation, computer-generated, but incredibly beautiful and incredibly horrific. It is the animation of a star being ripped apart by a black hole that it passes too near. It is as powerful a work of art as I think I've ever seen. Exactly. Exactly.

In fact, when you recognize that art exists on all levels of scale, and what I mean by levels of scale, the universe is comprised of things at the smallest level between quarks and muons and electrons and tiny particles right up to galaxies. But they transition through atoms and cells and microorganisms and colonies and biospheres and solar systems and so forth. Powers of ten. Right. It's like the powers of ten that Charles Eames did, which is such a famous thing.

If you could model what was going on inside a human cell or inside an atom or even just the flowers in the field or what have you, and put yourself as a traveler, not necessarily a time traveler, but a realm traveler, you can create what is called evolution as art. As evolution takes place, it produces magnificent art at all levels of scale, from the electrons done by Eric Heller up to the tremendous photography by Hubble Space Telescope and beyond. And I am fascinated by this concept of evolution as art. But to model the evolution, you have to understand the physics and the chemistry and the math. And then you immerse yourself within it and watch the beauty unfold. There is another kind of art combined with good science,

which you have become one of the masters of, and you've been doing it for a long time. Hopefully we'll talk about the culmination of one of these artistic efforts more after we take a break. But I'm talking specifically about your role as a mission designer for JPL, for NASA. What was the first one that you first really got to use that title? Probably the pair of Mars missions in 1969, called Mariner Mars 1969. The two craft were called Mariner 6 and 7. I was at the time the systems analysis project engineer, which was sort of like an architect for navigation and mission design.

I love that role. I mean, where I wanted to be an architect for real, I mean, when I look at Frank Gehry's Disney concert hall, I think I could have done that, you know, but I got on the, I was off on a different career because I really relate to that. I mean, that in essence is a huge piece of magnificent sculpture in its own right. But the beauty of designing missions is you get to be an architect again. Instead of building a building, you're building a mission. But you have to not only have a view of how the entire thing fits together,

the flight system and the ground system and the science objectives and how the trajectories follow the laws of Kepler and Newton and so forth like that. And so it's like putting a big puzzle together where the requirements are the scientific objectives and the end result is a mission that is reliable and can execute those. But you still have to worry about details, little details. And I always get confused between the two great people. One said the devil is in the details and one said the opposite. Yeah.

Don't sweat the details. Right. Or I guess the other said the beauty is in the details and one said the opposite. Yeah. Don't sweat the details. Right. Or I guess the other said the beauty is in the details. It's true. It is very satisfying to take the education in the sciences, in the mathematics, in the physics, and then actually be able to apply it to something and apply it with great care so that you don't overlook anything. I mean, it only takes one mistake to lose one of these missions. Yeah.

I was forced, and in the 40 years I worked at JPL, I was associated with 11 out of 11 successful missions. And so I don't have to lie awake at night worrying about the one that was lost. Let me stop you there. We're going to take a quick break and come back and pick up with this. And we do want to, and I think we'll be able to do this pretty easily, segue into a mission that you designed, which is now going into what is called, I guess, the encounter phase. And that is Cassini, which is arriving at Saturn in just a couple of months.

On June 30th, this huge machine will be making turns, firing its main engines for 97 minutes and going into orbit around the ring planet. Excellent. Charlie Colhaze, stay with us and we hope all of you will stay with us. We'll be back right after this. 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. Charlie Colhaze is our guest on this edition of Planetary Radio. Mission designer for JPL, a career with them going back about 45 years.

Right, 1959. And you said you're still going in two days a week. Oh, I know. In fact, if I hadn't been young, I think I would have passed out. In May of 1960, I had to make a presentation on an early Mars mission, and I walked into a small conference room, sat down. That was when we had blackboards and not whiteboards. We had chalk.

No PowerPoint. Right. And two or three minutes later, in walks Dr. Pickering, who was director of JPL, and with him Dr. Werner von Braun. And I thought, oh, my gosh. And everybody knew who von Braun was, and his head is massive. I mean, he radiates intellectual energy. And I was in a daze as I staggered to the blackboard

and tried to go through this with these two brains gazing at me. We've got to get you back sometime just to talk about history like that because we need to capture some of those other stories that are in your head. But you're still making history because this mission, Cassini, which has been on its way to Saturn for a good long while now, has a trajectory alone, ignoring all those other factors you talked about a few minutes ago, but just a trajectory, which is, I think, one of the highest statements of art and science that anybody could think of. Didn't it get gravity assists four different times? It did. It did. isn't quite powerful enough to send the payload directly from, let's say, Earth to, well, in this case, Saturn,

then you need to use gravity assist to pick up speed. And sometimes you even go into the inner solar system to gain speed. Dr. Roger Diehl and Dr. Chin-Wan Yin did some wonderful work there and found a launch that went from Earth to Venus and back to Venus, and then on the same leg with Venus that second time, Earth again, and then Jupiter, and finally on to Saturn. So that assist was Venus, Venus, Earth, Jupiter. Now those four swing bys have been done, and the spacecraft is on its final leg to Saturn. It will arrive in the evening Pacific Daylight Time on June 30th.

The interesting thing, if you added up the gains from all the gravity assist from those four swing-bys, it's in the vicinity of, let's say, 21 kilometers per second, okay, which is, I don't know if your audience is metric or English, but it's a lot. It's a lot. I mean, if you want to go to miles per hour, you multiply it by 2,230. So you're looking at 45,000 miles an hour or so. Now, that's a lot of gain from the planets, and it's not for free. They're each slowed by a minuscule amount in their orbits. When Voyager 1 swung by Jupiter in 1979, it gained 16 kilometers per second.

Wow. And Jupiter lost one foot per trillion years of speed. Well, not only does Cassini use gravity assist to reach Saturn, but then it uses 45 swing-bys of Titan, which is the largest moon of Saturn. It's actually bigger than the planet Mercury, about a little bit. And we do 45 swing-bys of Titan to shape the orbit around Saturn to put us in different positions to observe the rings, to make close fly-bys of many of the other moons.

Now, Saturn has 31 now. Yeah, probably at least that. It's a big number. If you add up all the gravity assists from the 45 Titan flybys, you get more in total than we got from the four planetary flybys. Wow. So the Cassini mission is a tremendous demonstration of a beautiful relationship of three bodies when they interact with each other. When did you guys figure all this out?

This thing has been in space for how many years now? About six and a half. We were working this out. See, I was moving from Voyager on to Cassini part-time after the Uranus encounter in 1986 and then full-time in 1989 after we went by Neptune. Not long after that, so let's say the early 90s, which would have been almost a decade ago, we were starting to search through the options for how to do this. So let's say early, mid-90s, we were working out the gravity assist. More than 10 years ago for a mission that is still dead on.

That's right. That's right. You talked about evolution in the first part of our conversation. How much does a mission like Cassini evolve as the mission is underway? I mean, obviously there are course corrections that have to be made, and this is all stuff that I'm sure you had to take into account, knowing how much fuel the reaction control system had available and so on. But how much do things really change? Well, if we've done the analysis correctly, then the changes are only within the tolerances of the analysis in that case. In other words, there had been no surprises thrown at us. And so we've known where each swing-by-corridor is at each planet,

where the maneuvers are that will correct for the navigation errors as we go through those corridors, and as a matter of fact, how much propellant to allocate for that. And that has all played out reasonably well. As a matter of fact, it would be incredibly hard to change this because you're getting so much speed off the planets. Once you set this game of billiards, start it going, you really have an awful time leaving it because you've launched counting on going into Venus for the first assist and coming back to Venus again for the second one.

Earth is not far after that second Venus assist. You can't bail out of this very well. And so you have to do it right and then execute it. And that's the way Cassini's going. And so now, 25 years or thereabouts after you started work on this project, it is now reaching its goal, the great planet Saturn. How do you feel about that? That's kind of an obvious sort of broadcaster question to ask, but it must have you feeling and thinking in a certain way. Well, yeah, I'm happy about it because Cassini and another mission called CRAF, which was Comet, Rendezvous, Asteroid, Flyby,

were both part of a program called Mariner Mark II, which was sort of the last of the big expensive missions. And CRAF got canceled by the Office of Management and Budget, and Goldman was under pressure to cancel Cassini as well. But back in the early 90s, a famous letter went from the head of ESA, a man named Luton, to Vice President Al Gore with copies to people that basically said Europe would view very dimly any cancellation of Cassini because we had, ESA was heavily involved. They have spent $220 million or the equivalent on the Huygens probe.

The probe that was here at Titan. Right. There were 18 countries around the world involved. And when Golden, as he wanted to usher in better, faster, cheaper, looked at this last of the giants, I mean, it was less than an order of $3 billion mission, very expensive mission. It was very tempting to think about canceling it. And that letter stopped him because he did not want to risk ruining our international relations. The great thing is that we made this big investment.

There were people that were worried we had too much money riding on a single mission. And here we are six and a half years later. The spacecraft is in perfect health. The mission is right on target. We're getting pictures back from Saturn that are dazzling. We have a tremendous high-resolution camera aboard. The spacecraft's reaction control system is able to hold this camera very steady for these images. And we've already seen the two moons, Pandora and Prometheus.

We've seen two storms merge in the atmosphere of Saturn. And here we are still several weeks away. The mission looks like it's going to be a real winner. And those people that were worried about the investment can breathe a sigh of relief. We're pretty much out of time, Charlie. I just want to maybe finish by saying I would think that you and Frank Gehry can both look back on some pretty amazing accomplishments. Well, thank you, Matt. It's been fun to be on the program. Charlie Colhaze has been our guest. Long time history with JPL that continues today as he

begins work or continues work on a mission which will be a topic of conversation on this radio show very soon. It's that Jupiter icy moon observer, Charlie, I think. Orbiter. Orbiter. And, of course, we'll be covering Cassini. And, Charlie, I hope you'll come back and talk to us more about that and other things in the future. Yeah, I'd be happy to, Matt.

Planetary Radio will continue right after this from Emily. I'm Emily Lakdawalla, back with Q&A. You can calculate the masses of the planets by measuring their orbits. By using telescopic observations of the planets and some simple trigonometry, you can determine the sizes and therefore the volumes of the planets. Mass divided by volume gives you density and the first big clue to what the planet is made of.

Of the common substances in the solar system, the densest material is metal, which is about 10 times denser than water. Rocks are about four times more dense than water. Ice has the same density. And the least dense material is gas. Mercury, Venus, the Earth, and Mars all have relatively high densities, requiring that there be metal cores underneath the rocky surfaces that we can see. Saturn and Jupiter, on the other hand, are much less dense. That means that their interiors must be made mostly of gases, especially when you consider that the extreme pressures at the centers of these giant planets compress even gases to relatively high densities. Generally speaking, planets are densest near the sun and decrease in density as you travel

outward, a fact that has to do with how the solar system first formed. 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 on Planetary Radio, which means that we're joined by Bruce Betts, the Director of Projects for the Planetary Society. Bruce, you stand cool here.

Boy, it was hot earlier this week, but it sure made for pretty clear skies over Southern California. It certainly has been beautiful, and in fact, there are all sorts of neat things to see in the night sky. Let's talk about them, shall we? We've got four beautiful planets. You can see with the naked eye in the early evening, look for Venus, very bright in the west, and Jupiter slightly to the east, but mostly overhead. Mars slightly to the upper left of Venus, and Saturn in between Mars and Jupiter.

But let's get to some special events this week, at least for some of you out there. There is a total eclipse of the moon that will occur on either the evening of May 4th or the morning of May 5th, depending on where you live. It is visible from almost all of the populated world except for North America, where it is not visible at all. Lucky us. Yes. And South America will be tough. But if you're in Europe, it's ideal in the evening.

If you're over in Asia or Australia, you'll pick it up in the pre-dawn skies. And so I suggest going online, and you can find some places that will give you the exact details on where to look and when. But basically, if you go out on that evening and find the moon, it will be going into total eclipse. At least you know the solar system is fair and that eventually our time will come again in North America. Oh, our time will come. You're not going to sing, are you? No, that's slated for later in the show.

Right now, I'm going to tell you there are also a couple comets out there that you may be able to see naked-eyed, at least with binoculars. Take some binoculars out, and those also, I'll give you some more details on them in the next two or three weeks, but for the next month or two, we've got one that was discovered by the Linear Survey, and one

that was discovered by the Neat Sky Survey, and they are both coming fairly nearby, playing with Earth, and should get, for those playing in astronomical magnitudes, anywhere from magnitude 2 to 4, but that's spread over a big area. What it means is it's going to be tough if you're in a populated, bright area. I've got to ask, the NEAT Sky Survey, what clever guy came up with that acronym? The NEAT? Boy. What clever guy came up with that acronym? The NEAT?

Boy, that's really neat. Well, they did call it SPIFI, but they couldn't quite get it worked out. Well, you've got to figure near-Earth asteroid gives you an NEA. Yeah. That part's actually more challenging to come up with linear, which also has near-Earth asteroid in it. You're so curious, Matt. I am. Let's go on to this week in space history.

On May 5, 1961, Alan Shepard became the first American in space aboard Freedom 7. Let's move on to Random Space Fact. And the whalers. Sorry. Did you know, Matt, that there are a number of professional surveys now looking for near-Earth asteroids? I knew of one or two, yeah. Yeah, and some of them have names like linear and neat. But it's also, there's a lot of neat amateur stuff going on, and the Planetary Society supports that through our Shoemaker-Neo grant awards. And so these surveys are coming up with not just things that are a threat to home sweet home,

but other cool stuff that may never get that close to Earth, but is still pretty fun to look at if you go someplace dark with binoculars. There you go, exactly. It all fits. It all fits together. It all comes together. On to the trivia contest. Last week we asked you, on the radio anyway, we asked you what the temperature is on Mars where carbon dioxide freezes out.

Or the flip side would be where does its sublimate go from a solid to a gas. This turns out to be basically the minimum temperature you can achieve on the surface of Mars because you're freezing out the main atmospheric constituent. How did we do? Well, I caused a problem. You said very clearly Mars, and we had a lot of people enter who said, well, here's what it freezes at on Earth. I don't know what it freezes at on Mars because they recognized quite accurately that it would be different on Mars because there ain't much atmospheric pressure on Mars.

And so, in fact, it freezes at a lower temperature. Right. On Mars it freezes at a lower temperature. Right. But Mars, it freezes out, by the way. The answer is 149 degrees Kelvin, approximately, which gives you approximately minus 124 degrees Celsius. We're going to have to go, because on the website. The website, we didn't mention Mars. Right.

So we did the random selection of anyone who got either the temperature for Earth or Mars correct. That was the one I was looking for, anyways, on Mars. Now you can impress your friends. Call this temperature on Mars. And here is the randomly chosen winner, someone who has, I think, been in the contest before but has not won. So Greg Mindorf of Vancouver, British Columbia, congratulations. You won with your answer that carbon dioxide freezes at minus 78.5 degrees centigrade here on Earth.

Still chilly. Yeah. Not as cold. It's very. Keeps the ice cream cold in those push carts. Okay. For this week's trivia contest, switch gears some. Three humans went to the moon twice.

three humans went to the moon twice. And by going to the moon, I mean either orbiting, landing, or even just flying around the backside of the moon. Who were those three people? I could only name one of them. So those people who find out or already know, how can they enter our contest? Go to planetary.org slash radio and find out how to enter the contest there and win a glorious Planetary Radio t-shirt. slash radio and find out how to enter the contest there and win a glorious Planetary Radio t-shirt. Now, once again, those of you who are listening to us on WMUH in Pennsylvania, Allentown, Pennsylvania,

remember that. I know, we should be playing the Billy Joel song, I know. You guys got to remember that you're hearing the show a little bit later on the radio than most people, so go to our website. Go to the website. And you will see the current trivia contest, and you can get in on that and win one of those wonderful Planetary Radio t-shirts. Bruce, anything else?

No, that'll do it, Matt. Just want to encourage everyone to go out. Lots to look up in the night sky. And go out there and think about dogs. Thank you, and good night. Woof! Bruce Betts is the Director of Projects for the Planetary Society. Look what I started. Director of Projects for the Planetary Society.

We're speaking to you today from the headquarters of the Society in Pasadena, California. Back next time with more Planetary Radio. By the way, you'll find a link to Charlie Colhaze's website at planetary.org slash radio, along with archives of all our past shows and the current trivia contest question. Have a great week.