Interview with Carolyn Porco

July 6, 2005


CI:††††† How did you get into science in the first place? What attracted you to your field?

CP:††† I was attracted to science for as long as I could rememberóeven as a child I found it very appealing. The lack of subjectivity appealed to me especially. Truth suddenly wasnít the opinion of some great authority. Mother Nature was, and is, the final arbiter. To me, science means that there is an absolute right and wrong, and itís not determined by someoneís opinion. I found that very compelling, and right from the beginning, I gravitated towards it. I was also always very curious, though I canít say that I was a terrifically good student when I was a youngster. I got good grades, but I wasnít one of those people who constantly studied.

†††††††††† As I became a young teenager, I became very interested in philosophy and religion. In 1966, when I was about thirteen, I got very interested in Eastern religion, which is what eventually got me into astronomy. I didnít grind telescopes and get into it that way. Philosophy, religion, and thinking about the big questions got me interested in astronomy. What are humans doing here? What is our circumstance? Where are we and what is out there?

CI:††††† Did you grow up in a religious tradition?

CP:††† I grew up in an Italian Catholic family, but they werenít really churchgoers and no one in my family was seriously religious. They believed in God, but they didnít practice in a formal sense. They sent us to Catholic school to start out with, mostly out of a sense of duty. I just became very interested in religion. I was interested in science for as long as I can remember, and then religion brought me to astronomy as a teenager. When I look back on it now, it may have been the Beatles and their move towards mysticism and Eastern religions. If thatís the case, I owe my interest in astronomy to George Harrison.

CI:††††† Your interest in science and big questions could have taken you inwards to biology or a life science. Why did you choose astronomy rather than physics, biology, or other sciences?

CP:††† Thatís a good question. It was our cosmic situation that I was interested in understanding. What are humans doing here? Whatís out there? Because here we are on this little planet, and itís so big out there. Physics is the basis of all science and life, so I was very drawn to physics.

†††††††††† I think that religious people get out of religion what I get out of astronomy and participating in the exploration of our Solar System. It means involvement and engagement in something so much bigger than I am; something so much more important and meaningful. Itís something that allows me to put my mark on the future, and sign my name to the great declaration of human thought. I think that religious people get that out of religion. They want a connection with something bigger and more eternal than they are.

CI:††††† Youíve described the juxtaposition that makes research or science intoxicating: the ability to ask very big questions and actually believe that you can answer them. Itís quite profound.

CP:††† Thereís been nothing more intoxicating to me than those momentsóand Iíve had a few of themówhen I thought that I had discovered something that nobody else on the planet knew! Eventually, of course, you tell your colleagues, and everyone scrutinizes your idea to make sure itís worthy. But thereís nothing more giddy and intoxicating than that brief moment when you know that youíve found something about nature that nobody else knows. Thatís the rushóthe ďeureka moment.Ē

CI:††††† Tell me about one of those moments.

CP:††† I got that rush while I was working on Voyager; that started when I was a graduate student. Voyager had discovered the spokes in the rings of Saturn, but no one knew how they behaved. There were so many things discovered by Voyager and there were not enough scientists on the science teams to analyze it all, so some very interesting topics fell into my hands as a graduate student. One of them was the spokes. This research wasnít even promoted or encouraged by Peter Goldreich, my thesis advisor at Caltech. It wasnít that he discouraged it; he just didnít tell me to study it. I looked into the business about the spokes all on my own. Because they were new and no one had seen them before, I had to start with something simple. I did a time-series analysis of their appearance in the rings and found that they came and went with the magnetic field period. It was a small thing, but I was so excited that I forgot to eat and couldnít sleep.

CI:††††† That reminds me of Isaac Newton. When he really got into a calculation, he would forget to eat, forget to bathe, and he would entirely dismiss personal hygiene. His manservant would have to come and force him to take care of himself!

CP:††† I guess there are times when we share that with the greats. Another time was when I was working on the Neptune ring arcs and figured out how they worked. Those things are very exciting. You know youíre going to make big discoveries when you are involved with a space mission like Voyager, because youíre going to an alien place with equipment that has never been carried there before and is a quantum leap over anything thatís ever been there. You see things that have never been seen before. Thatís the rush, and thatís the fix.

CI:††††† Presumably, thatís the attraction of space missions that counters the long wait and uncertainty. Itís not just an incremental gain; you make a dramatic gain in what we know about the object being visited.

†††††††††† Let me ask about the rings of Saturn. When you look at the rings in full detail, you knew how to explain what you saw. For someone who doesnít know anything about gravity or planetary rings, they might look at those gorgeous patterns structures and say, ďWow that has to be evidence of Intelligent Design, or the Hand of God.Ē How do you explain to someone that we really can understand the incredible richness of phenomena in a planetary ring system?

CP:††† It depends what people mean by Intelligent Design. I hear this phrase more and more, and I presume itís coming from religious people saying that the world is so full of complexity that it has to have been designed by someone intelligent. In science, we believe that everything will boil down to one of the four basic laws of nature. There are many manifestations of those laws, and when you talk about Saturnís rings youíre basically talking about the law of gravity, and in some circumstances the law of electromagnetism. Thereís an entire universe full of complexities that can arise from these two basic laws. The complexities are the result of these laws, and are not necessarily designed by anything. But someone could also say that the laws themselves are the result of Intelligent Design. Itís a complex question.

CI:††††† I think itís an important question for scientists to address. It would be like somebody saying, ďHow could you develop an eye? Itís too complicated.Ē An evolutionary biologist would explain that you start with cells on the outside of a creature which are sensitive to light, eventually a gel-sack develops and so on, and you could incrementally get an eye. Teaching someone that process is analogous to showing someone a picture with the rings of Saturn, and saying, ďItís not magic. Itís not the hand of God; we can understand it, and this is how it works.Ē Itís very powerful to do that, and it needs to be done all the time.

CP:††† When we look at the rings of Saturn and other things we donít yet understand, many forces play into each other in a complex wayóespecially when youíre talking about particles interacting with each other. Since we understand the basics of it, working out the complexity is just something that is yet to be done. We do fundamentally understand the principles at work. If the person wanting to promote Intelligent Design went on to say that the principles themselves are intelligently designed, thatís a more difficult question to answer. I think the approach is to say, ďThere doesnít have to be a motive. Someone didnít have to create them.Ē To even ask the question of why those laws are the way they are anthropomorphizes them.

CI:††††† The experience you had on Voyager early on must have convinced you that you wanted to be associated with space missions in your career.

CP:††† I went to Caltech because I knew that I could end up working in the planetary program. When I chose my graduate school, I knew that I wanted to be in the American space program. I consider myself very fortunate that I ended up doing what I wanted.

CI:††††† What was it like working on those big teamsóespecially when you were a young scientist?

CP:††† It was frightening in the sense that it was very hard. I was not even a team member when I first started out. I had to hold my own and work in a very competitive environmentóthe kind where everybody tries to outdo each other and come up with the most brilliant ideas. This happens in real time, and with data coming in and people standing around computer monitors, I did find it rather difficult. Everybody was male in those days; my team today is still mostly male, except for one or two female junior associates.

†††††††††† Women scientists have their work cut out for them. Women in my generation generally feel that itís not acceptable for a female to behave the way an individual has to behave to be successful in a scientific environment. So there is mental arm-wrestling that goes on when scientists get together. Much of a personís reputation depends on how well they handle these circumstances.

CI:††††† It seems ironic that it still happens in space mission teamsóthey have a very tight, collaborative framework compared to other science projects.

CP:††† I think itís getting better. For example, I think Elizabeth Turtle has an easier time of it than I did with Voyager, and thatís good. It might be because as a woman I am the leader of the Cassini imaging team.

†††††††††† Some of us have already fought those battles. It was difficult breaking in, but Iím from New York, and I grew up with brothers and no sisters. I knew about arguing, fighting, and holding my own because of them. Iím talking real brothers; really aggressive boys. They used to chase me around the house with dead bugs, lock me in closets, and I was forced to play football and baseball at an early age. I feel that it actually helped me feel more comfortable. Now Iím not uncomfortable to be the only woman sitting in a roomful of men, because I got used to that as a kid. But you can imagine a young woman whoís not used to that. Itís still imbedded in our culture.

CI:††††† What do you think is different about the culture in the space sciences? Why are all the physical sciences still dominated by males?

CP:††† I think sciences that are more abstract have the reputation of being more macho. The more abstract the science, the harder it is supposed to be, so only the ďreal menĒ do it.

CI:††††† So, youíre talking about intellectual elitism within fields?

CP:††† Thatís right. Physics and space science are very mathematical, and that still carries an aura of machismo with it. Itís only the intellectual elite that are trained to grapple with abstract concepts. I gather that biology is actually becoming more abstract. It used to be more lab-oriented, but now there are mathematical models for molecular behavior and other processes.

CI:††††† Let me ask a broad question about how planetary science is perceived by the public. People know that Earth is special in the Solar System, but they might generically think that the rest of the planets and moons are just rocky or gassy things that arenít very special or interesting. However, when you see them up close and have enough information, you find theyíre worlds with their own personalities and interesting features. Thatís an awareness weíve only gained in the last decades.

CP:††† Thatís right. The field of planetary exploration isnít even fifty years old. They are worlds. We find that when we look at all of the bodies in the Solar System, almost all of them that have solid surfaces. Iím not talking about comet-sized things, but even looking at the pictures of comet Temple-1 from Deep Impact, Iím amazed by its geography. If you look at the reasonably big bodies in our Solar System with solid surfaces, many of them donít have matching halves. One hemisphere doesnít look like the other; there are big hemispherical dichotomies. That indicates that planetary scale processes alter their surfaces. Theyíre not just bland surfaces that are being pock-marked with impacts for four billion years. Many of them have undergone internal processes that have evolved their surfaces.

CI:††††† Itís also changed our thinking about life in the universe, hasnít it? Now when we look for life in a solar system, we have to consider moons in addition to terrestrial planets.

CP:††† Yes. We also have to consider the interiors of these bodies as well and not just the surfaces. It seems that life can crop up anywhere. Even in places where there isnít any sunlight, some life forms can feed off chemical energy. And where thereís abundant chemical energy, you might expect to find life.

†††††††††† We can find life at the mid-ocean vents, where thereís no sunlightójust lots of chemical energy and heat. But we can also find life in really cold places like the Antarctic ice. That opens up a much broader range of environments throughout the Solar System where we might be able to find life. Organic materials are abundant. Theyíre found in lots of places in the Solar System, and certainly in the outer Solar System. There are probably no organic materials on the surface of Mars now because theyíve been oxidized and torn apart by UV radiation, but if you go into the subsurface where itís warmer there might be liquid water and organic material. It seems almost a foregone conclusion that there will be living organisms on other planets.

CI:††††† We used to define a habitable zone as a terrestrial planet with a nearly circular orbit where water could exist in liquid phase on the surface. What would be the definition for a habitable zone in a solar system now?

CP:††† I think we can discuss habitable zones for water-based life. If you relax the requirements and consider methane, then Titan looks like a good possibility. The issue for planetary exploration and remote sensing is whether we could even recognize life that isnít water-based. Even if not every planetary scientist would articulate it like that, one of the main goals in exploring the Solar System is to understand what the cosmic or planetary context is for life. I think a cardinal goal is just characterizing the surface and subsurface environments in our Solar System, and then attempting to search for evidence of life in some of these environments.

CI:††††† Weíre stuck with only one example of life to study in the universe, but when you talk about the range of planetary and geological processes, thereís a lot to learn from our Solar System. Processes like tidal heating or subsurface processes that could generate enough energy to support life may be universal.

CP:††† Sure. Itís certainly true that the broad range of planetary processes we see in our own Solar System are likely to crop up elsewhere. The corollary of that is also true; there may be processes or manifestations of processes in other solar systems that we donít see here. What would happen with a Jupiter that was at the distance of Earth from the Sun instead of its current location? There may be a host of other phenomena that we donít get the opportunity to view here.

†††††††††† Another reason to explore planets is to give us other examples to study. By studying other planets, we can separate what is common and what is unusual about Earth. Titan, for example, has a mild greenhouse effect at its surface. The temperature is twelve degrees Kelvin hotter than it would be otherwise. That greenhouse effect is actually more like our own than any other in the Solar System. Right now, weíre just searching for more information in order to understand whatís so special about our planet.

CI:††††† In the search for life, weíre focusing more on certain bodies in the Solar System, namely Mars, Titan, and Europa. Are there any other moons that are intriguing enough to send a probe to if there were resources to spare?

CP:††† Callisto and Ganymede. Theyíre also believed to have subsurface oceans.

CI:††††† Whatís the evidence for that?

CP:††† Magnetometer evidence. It can be explained by a subsurface ocean having some level of salinity.

CI:††††† Are these oceans big enough to have some sort of internal heating?

CP:††† Ganymede and Callisto are bigóabout Titan-sized. Itís believed that they have subsurface oceans. Io, Europa, and Ganymede are in a three-body resonance together, so thereís probably enough flexure for those to have heating, too. I donít know about Callisto, but I know that the three non-volcanic Galilean satellites are candidates. It would be good to study them as a trio. If thereís subsurface water, itís probably not as close to the surface as it is on Europa.

CI:††††† Thatís probably a surprise to many people. We tend to think of Earth as the water planet. Europa was a surprise, and maybe now there are a couple other bodies with subsurface oceans. Water is an abundant molecule in the universe, so maybe we shouldnít be so surprised.

CP:††† Water forms most of the outer Solar Systemóthe moons out there are mostly ice. You need enough rocky material to have a heat source because the rocky material is radiogenic and gives off heat. You could also have a process like tidal heating, something to flex, or a resonance to create heat. As we understand it now, life would be related to water. Enceledus is very peculiar; it certainly looks like at one point in time it was heated. We have the closest flyby of the whole tour with Enceledus next week.

CI:††††† Letís talk about the big picture of a mission like Cassini. What has Cassini been like for you?

CP:††† Itís not so much a mission as a way of life. In a way, I knew this was going to happen when we were selected. Of course I was gleeful for about fifteen minutes when I was told I had been made the Cassini Imaging Team leader, but I sobered up really quickly when I fully realized what I had bought into, and how much work it would take to pull it off. It turned out to be far more than I expected.

CI:††††† When did it all start for you?

CP:††† November 13, 1990.

CI:††††† I imagine it would be like raising a child. The payoff would come ten or fifteen years later.

CP:††† Itís similar in the way of the commitment. There are joyous moments, certainly, but also outrageous frustrations, and a lot of hand-wringing. This mission required inordinately long periods of time when I had to be obsessively devoted to it. To pull it off, I had to clear the decks of everything else, including any semblance of a normal life.

CI:††††† Yes, the timescales are dictated by factors out of your control. If thereís a crisis in the mission, you have to drop everything, right?

CP:††† Probably every project could say this, but it would have been much better if we had been better funded. We were woefully underfunded. We received several times less money than the Galileo imaging team got previously, and they had far less work to do. I think itís a result of this push to have more and more missions. NASA wants to look very productive, and we as a community want to be productive. We want to go to comets, asteroids, planets and moons. We want to conduct fanciful missions like smashing things into comets, which is outrageously great. But the downside of all that is that weíre so over-committed that any one mission is not given enough money to do what it needs, and people are asked to work excessive hours. Itís like being asked to sprint for the duration of a marathon!

†††††††††† In the days of Voyager, there were years between encounters. For those several years, you could have a reasonably normal life. You looked at the data from the last encounter and published papers. You had several years to plan the next flyby. Then as you got closer to the flyby date, it became more intense. But there was only a period of several weeks around each encounter when you got into an obsessive mode. Here weíve had to be in an obsessive mode for years on end; itís become a way of life. Iím sure the Deep Impact people had to do the same thing, but their whole mission was only about six years long, and ours has been fifteen so far. It really requires a lot to commit oneself to one of these missions.

CI:††††† Were there any times when the mission was in jeopardy?

CP:††† There were tough times in 1992. Just a couple years after we were selected, we had to descope, which is a word coined by NASA. It means that we had a budget cut and had to remove capabilities from the instruments and the spacecraft. Then a couple of years later, the administration started looking closely at the project. They had a budget crisis and Cassini looked like an attractive option to cut because it was a big, expensive mission. At that point in time I was asked to go speak to the Office of Science and Technology Policy to try and explain the value of the mission. I also spoke to the House Authorization Committee. So yes, there were times it was politically in trouble.

CI:††††† Did they understand the goal of planetary science? Did it mean something deeper to them than just another budgetary item?

CP:††† Except for one visit, I always got the impression that it did resonate with them. That one time, though, I had gone to the Office of Management and Budget to talk about the Pluto mission, and they just didnít want to hear about it. They were so obsessed with Europa that it seemed like they had already made their own decision. I find the developments with NASA and with the government in the last several years absolutely unacceptable. Politicians are basically dictating science policy. In my mind, this is a very dangerous path. I think that scientists need to band together to stop it. We need go on strike or something. I came up against this when the OMB said that they wanted to go to Europa. I tried to explain that while Europa is important, we shouldnít forget about Pluto, because Pluto is also very important scientific reasons, but the guy didnít want to hear it. It wasnít until NASA asked the National Academy of Sciences to call together a Solar System decadal survey to come up with priorities that some of it got sorted out.

†††††††††† So, except for that one time, Iíve always received a warm and excited reception when talking about planetary exploration and what scientists want to do. I think thereís a lot of enthusiasm and support for what weíre doing; thereís just not a mechanism for people to express that support, especially financially If we did something as simple as asking on everyoneís tax form it they would give an extra dollar to support astronomy or space exploration, weíd have ample funding. Of course, it could never happen in practice because there would be a billion other organizations and groups that would want to do the same thing,

CI:††††† There seems to be substantial receptivity towards scientific endeavorsóeven amongst politicians. But NASA will always be competing for funding with many other big needs groups. At that point there are trade-offs that have to get made.

CP:††† NASA is up against irrelevant circumstances that dictate its direction. Where is NSF in all that?

CI:††††† Theyíre bracketed with NASA in that same grouping.

CP:††† It makes no sense; itís not a lot of money.

CI:††††† When you were talking about descoping, you reminded me what an amusing concept that is. In the history of NASA, scientists are usually so ingenious that they save most of their science despite being descoped. NASA can then turn around and say that they could do what they needed to do with less money anyway, and thereby justify awarding less funding the next time.

CP:††† Yes, thatís another thing thatís happening. They know that scientists will work amazingly hard for nothing. They have us over a barrel, and thatís why I think that scientists have to get savvy. We need to get political and put our foot down. I feel like the scientific community is akin to being the abused spouse of a domestic partnership with NASA and the federal government.

CI:††††† It sounds like we need a revolution. This is a little heretical, but we may need the privatization of space. A couple of governments essentially have a monopoly on space exploration and space scienceóthere are good and bad things about that. If the arena is opened up to private enterprise, you wouldnít necessarily lose pure science. We need more competition, more players. With that comes more funding mechanisms so that we wonít be forced to go to the same NASA well thatís run by the same set of bureaucrats going through the same political process every year.

CP:††† Thatís right: more mechanisms, more avenues and competition. Competition is really key.

CI:††††† Back to Cassiniótell me about the excitement of a year ago. What was it like to finally get into orbit?

CP:††† It was an enormously gratifying to see the fruits of our labor.

CI:††††† Where were you when that was happening? In Europe?

CP:††† No, I was at JPL; my team had to be the entertainers. We had to stay up all night to get the pictures ready for the press conferences the next day. We had the worldís attention, so it was very gratifying and wonderful. Of course itís also exhausting, but youíre really happy because all your work has paid off. On top of all of that, you have the privilege of seeing things nobody in the history of the universe has seen beforeóor at least in the history of Earth. Thatís the rush. Itís like winning the gold medal at the Olympics.

CI:††††† I imagine that it would be quite emotional at that point.

CP:††† Yes, very emotional. The subsequent months were completely heady. There was picture after picture of all sorts of beautiful things. Our instruments continue to work beautifully and the spacecraft is working beautifully as well. There could have been a disaster, or we could have had something fail. But so far nothing has. We were very fortunate; the kid graduated high school with honors.

†††††††††† Another superbly thrilling moment was when the Huygens probe landed. I didnít have to be the one doing the entertaining for that; my team didnít have to stay up all night to get everything ready. That almost had a bigger impact on me than the Saturn orbit insertion, maybe because I had the freedom to absorb the whole thing and didnít have any responsibilities. When we landed on Titan, I felt like a different person. I felt like Iíd been hit over the head with a frying pan. I was stunned; it was just such an amazing, amazing achievement. To have those pictures tell us right off the bat, unambiguously, that stuff flowed on the surface of Titan was the thrill of thrills.

CI:††††† Right! And I think it took a while for it to settle in with people. One of the problems is that itís been thirty-five years since we set foot on the Moon. Many young people have the notion when they look at the space age that not much happened after that. But a mission where youíre doing real-time exploring of new worlds hundreds of millions of miles away vaults us back to the frontier again. I hope that will generate a new wave of interest among young people and encourage them to reengage in this pursuit.

CP:††† I think it will. Many peopleónot billions of people or even millions of peopleóbut many, visit our websites. Theyíre looking over our shoulders. But I do think we should work harder to get science into the public arena more. If we make use of other avenues, we can connect to people directly and get their financial support. We need to use television in the way that other disciplines and enterprises use television.

CI:††††† What have the most scientifically interesting or exciting things from Cassini so far? What things were you not expecting?

CP:††† Thatís hard to say, because we were expecting to find and discover new things that would puzzle us. The stuff that I found most intriguing is the complexity in the rings, which was a phenomenon that we thought we understood. We had a very simple model, but now that weíre looking closely, weíve found this simple model inadequate. Iím intrigued by what weíll learn about the rings when we understand why it is inadequate. It is going to be a real thrill work on how this gigantic expanse of debris behaves. Itís also going to be a touchstone for other disciplines in astronomy that deal with accretionósubjects like proto-planetary and proto-stellar discs.

†††††††††† I am also intrigued by the morphology on the surfaces of the satellites, because theyíre like autonomous worlds. I look at them and think, ďI could be walking on that.Ē Thatís how I think about it. I say, ďThis picture is so many miles across, and it would take me five days to walk across it.Ē Itís like hiking. I think about how long it would take to hike across one of our pictures, and what it would feel like to be there. That is the physical adventure by proxy. Itís not a real physical adventure, but our pictures allow us a means of at least imagining what it would be like to be there. Thatís the explorer in me, and I think itís the explorer in all of us who get involved in this. New terrain, new territory and horizons.

CI:††††† I imagine that the problem with a successful mission like that, especially with what we saw in Titan, is that you immediately have a whole new set of questions that you want answered right away, but there is no mission coming up. What is the next mission heading in that direction?

CP:††† There are various plans. No one has settled on any one thing, but they call for aerobots, balloons, and airplanes in the atmosphere. It would be good to have something that could go up and down to sample both the upper atmosphere as well as get closer to the surface. Most of the bodies in our Solar System have a very diverse geography. In other words, we shouldnít just touch down in one place, take a rock and go back to Earth, because that would be like landing in one place on Earth. The Antarctic is nothing like French Polynesia. The polar region on Titan may beóand probably isócompletely different than the equatorial regions. The same thing applies to other bodies. Thereís so much variety on the surfaces that you could probably spend a lifetime studying any one body.

CI:††††† In terms of a timeline, where do those follow-up Titan missions sit with respect to a Europa mission?

CP:††† This goes back to the work we did on the Solar System decadal survey and what we ought to be doing in the next ten years. The priorities were: visiting Pluto, orbiting around Jupiter, landing on a comet and returning a sample, going down to the surface of Venus, and returning samples from the lunar south-polar region. Those were the missions we considered most important to address the breadth of unanswered questions after the first forty years of planetary exploration. Basically, those are the reasonably middle-sized missions that we thought could be accomplished in the next ten years. Along with that, we hoped one big mission could be done. We chose the Europa mission.

CI:††††† Was there vigorous debate about that if you were only picking one big mission?

CP:††† Actually, it wasnít that bad. Europa had already excited many of us and I donít think there was much contention about it. But there was contention about what the next big mission after Europa should be. Some thought it should be a Titan mission, but I was in favor of a Neptune orbiter. I think we need to get back to Neptune to orbit and investigate, because itís different than Jupiter and Saturn, and peculiar in so many ways. Its magnetic field is peculiar, its satellite system is peculiar, and it has Triton, which we think is a sister body to Pluto.

CI:††††† Is Triton the one with nitrogen atmosphere?

CP:††† It has a very tenuous nitrogen atmosphere. Itís got geysers, geologic activity, and a polar cap. Thereís a lot to learn about processes that go on in the deep, deep coldóplaces where itís just thirty degrees above absolute zero. Itís really a remarkable place. In my opinion, it should be our next focus. But people also thought that Titan needed to be a focus as well. So itís up in the air as to what we do after Europa.

CI:††††† Give me a sense of the cost ranges of these upcoming missions?

CP: †† Medium sized missions are something like six or seven hundred million dollars and a big mission would be a billion plus.

CI:††††† Cassini was more than a billion dollars in the end, right?

CP:††† Cassini was 3.2 billion, but that 3.2 billion was spread over 18 years. People always forget that the 3.2 billion wasnít spent in one year.

CI:††††† These are hard choices, because as the politics of NASA change, you donít know how many new starts youíll get.

CP:††† Yes, thatís very frustrating, especially since Iím such a purist. Iím fifty-two years old, but I still have this child-like idea that science is the most pure, beneficial endeavor that could be undertaken by humans. It should be supported in a very special way. It should have a high priority in our social consciousness, and yet itís always such a struggle. I just donít understand that. Itís nothing but good, yet itís always a struggle.

CI:††††† If you look at the big picture, space exploration really is a young enterprise for humans. Weíve only had our civilizations for a couple thousand years and technology for a century or so. Weíve only been doing space travel for half a century. Are you optimistic that in long time scales we will stay committed to space exploration? Do you think we have a future in space?

CP:††† If we donít destroy ourselves, I believe that we do have a future in space. But itís not going to be steady progress. I think itís going to be two steps forward and one step back. Even in my lifetime, Iíve seen this process: we commit, we retreat, we commit, and we retreat. I think itís going to go like that. But I donít think itís stoppable, because I think itís a drive thatís very innate, and part of what we need to do to survive. When you get old enough to watch and observe people, you see that there is always a small group of people who do crazy things. It wonít be hard to find people to sign up for a one way trip to the nearest star. It might take twenty-five years or so until we figure out how to go faster, but people will want to do it.

CI:††††† So despite the political struggles of getting funding to launch the big missions, youíre still an optimist.

CP:††† If I could come back five hundred years from now, I would expect to see communities on Mars and possibly people taking extreme vacations or excursions to the Saturn system. We might be mining water on cometsóI think thatís going to happen.

†††††††††† When I was young in the sixties, I knew that I was interested in studying astronomyóthis was encouraged by movies like 2001: A Space Odyssey. I thought that by the time I was fifty weíd have telescopes on the moon and Iíd be going there to observe. That hasnít happened. In a sense, it is disappointing that we havenít come as far as we thought we would in the sixties. The initial stepping off the planet didnít lead to the results we were expecting by the time we all got to middle age.

CI:††††† I agree with you, but I think the curiosity and momentum are unstoppable, even if the rate of progress is subject to money, whims, and politics. Thatís what you find when you talk to people and get them excited by whatís being found. Maybe theyíre not going to do it themselves, but there are always going to be crazy people to take the chances, work for nothing, or do whatever it takes.

†††††††††† I had one other question. You have an asteroid named after you, right? Iím always jealous when I hear that, because itís so cool. Whatís it like to have an asteroid named after yourself? How big is your asteroid?

CP:††† I have to go look it up. Itís either twenty-five kilometers in radius or diameter, but I never remember which. It was thrillingóan honor. It meant a lot that someone had thought to do it. Itís not something I dwell on at all the time, but when I do dwell on it, I think about how itís as close to being immortal as Iíll ever get.

CI:††††† Is it observable? How bright is it at that size?

CP:††† Itís in the main belt. I tell people that itís in a stable orbit, but they shouldnít piss me off.

CI:††††† The best thing would be having an Earth-crosser named after you. You could go down in history for some future extinction.

CP:††† People would say, ďWe expected no less from her.Ē

CI:††††† ďShe went out with a real bang.Ē