NASA Podcasts

The Vision Behind NASA’s Kepler Mission
03.06.09
 
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Jesse Carpenter: The Vision behind NASA's Kepler Mission. Hi, I'm Jesse Carpenter and you're listening to a podcast about NASA's Kepler Mission from the NASA Ames Research Center. Planned for launch in March of 2009, the Kepler space telescope will observe one area of the universe continuously for a period of four years in its mission to identify the presence of planets that are similar to Earth. Today we have three Kepler project team members who are here to discuss the vision and the story behind the Kepler mission. Joining us in our studio are Kepler Principal Investigator William Borucki from NASA Ames, Kepler Deputy Principal Investigator David Koch also from NASA Ames and Kepler Co-Investigator Jon Jenkins from the SETI Institute. Welcome to everyone, and thank you for joining us. So Bill, tell us a little bit about the vision for Kepler.

William Borucki: If there are lots of Earths out there, there may be lots of life out there. And that's really the name of the game; is there life in the galaxy, or are we alone. So the idea was to make the effort to find the answer to that question, are there other Earths. And then other missions would come along and do the following steps: they would look at the atmospheres, they would find pre-biological molecules, our children's grandchildren would look even with more powerful instruments and they might be able to see continents and clouds and water. And, maybe we'll send a probe someday to these planets. So Kepler is one step in many steps. And it reminds me very much of what happened in the middle ages. They would be willing to build a cathedral and the first generation would build the floor, the second generation would build the walls, the third generation would put the roof on and enjoy it. People are looking to do this one step at a time. First find the giant planets, then find the small planets, then ask about their atmospheres, and then maybe go there someday. And so, that's really the vision.

Jesse Carpenter: Dave, what were some of the challenges you faced in the early days of developing Kepler?

David Koch: Bill began this quest long before the first extrasolar planet was actually discovered. People loved the science, but they didn't believe that we had demonstrated that we could actually do the science. And so we had to go out and prove that the mission was really feasible. So, we proposed in '94 to the first discovery AO. We didn't make that. And then 51 Peg was found and the race to find earths started heating up. We proposed again then in '96 and in '98 we came back and started building a real high-fidelity lab technology demonstration to show that you could actually measure this tiny signal with commercially available CCD's.

William Borucki: And that was quite a challenge in itself. When we first started out, that was one of the early criticisms; you're detectors aren't good enough. And so, there was a detector, not a very good one, an old one that was in the basement of Lick Observatory. So we built up a bunch of bricks, an aluminum can and we put the detector there, and liquid nitrogen on that, and for a couple of weeks we ran that experiment in the basement, by itself. And what we found, when the results came back, I remember Lloyd Robinson saying to me "Bill, I'm sorry, it can only do a part per thousand. It's not good enough." And I said, "Well, what we want we want to do, is we want to do some regression analysis. We want to use the mathematical techniques that help us pull a small signal out of the noise." And when we did that… voila. We saw the signal, and we saw it clearly. It was clear, even with a rather poor conditioned CCD we could do this job. And we then published a paper on it, and that ended much of the objection that we couldn't do it. But there were other objections. In 1996 when we proposed, one of the things they said was no one has ever done automated photometry of a hundred thousand stars simultaneously. Build an observatory and show us it can be done. So we had to build an observatory. And it's built at Lick Observatory. It's a small dome. We built the telescope. We built the photometer. And we showed, indeed, that we could build the mathematics, we could build the reduction, analysis programs and actually find planets. Now we never discovered any, which has always been a disappointment to me, but we have seen other planets that other people discovered, and we could show that we could do this in a very automated fashion. And that helped convince people that we should be given a chance to continue to prove we could do this job, as Dave was describing.

David Koch: And then we went into the lab and we demonstrated that we could actually see this tiny little change in brightness of a part in ten thousand, a change in individual stars when you were still looking at a large number of other stars, that you had stars that are very close together, stars that were much brighter than other stars in your field, all of the complications that you have in a real space mission, a really complex measurement. We included the spacecraft jitter. The telescope is always moving just a little bit, even when you're out in space, and put all this noise sources in just to demonstrate that this is feasible. It's not just you know, an ideal case you could do it, but in a real life situation that we could find this tiny little change due to an earth.

William Borucki: In a way we did that basically again mathematically. The signal processing is what allows us to do this. And Jon has really shown us there are some very powerful methods to do this. And maybe he'd like to describe them.

Jon Jenkins: I'd like to actually give an acknowledgement to Dave for coming up with a very innovative technique for actually introducing a part in ten thousand change into the brightness measurement that we got out of the lab and that was to put a very small ribbon of wire across this perforated star plate so that, and then to put a current through a wire over a hole and that current would induce a temperature increase in the wire and cause the wire to just increase its diameter a little bit, cover up a little bit more of that hole and therefore block out just a tiny smidgen of light that was allowed to go through that hole, image onto our CCD camera as a star image.

David Koch: The wire expanded by just five nanometers. That's the small change that you have to see in the brightness of that star.

William Borucki: About fifty atoms.

Jon Jenkins: Extremely small. I must admit, when I joined the team in 1995 and started working with some of the measurements of the sun's brightness variations that we had from the Solar Max Mission and then later from the SOHO Mission that I was a skeptic. How could you possibly find a part in ten thousand change when sunspots are five to ten times larger? And actually it's kind of interesting, we're sitting here in a studio and I can see the board with all the, basically an equalizer, and the way we go about it is actually we use a software graphic equalizer. You can imagine that the sun has a lot of stuff going on in it. It's actually kind of like a bell. It rings. It basically changes its shape due to waves passing through it. And so when you measure the brightness it's kind of like recording somebody singing, and it's a chorus, its not just one person singing. The transits that we're looking for are kind of like the altos or mix between the altos and the tenors. And so that's what we're listening for and so you can look at a graph of the light curve or measurements of the brightness of a star over time and you can't see the tenors. You can't see the transits. But what you can do with your graphic equalizer is you can dial down those knobs, pull those levers down to minimize the amount of noise, or the loudness of the basses and then baritones and you can turn down the sopranos, then and only then can you hear the altos and the tenors. And so that's really how we do it. And the mathematics that we use to implement that software graphical equalizer was invented in the late 80's and early 90's. And it's called wavelet analysis, but it was a tool that was invented, if you think about the scale of human endeavor, just in time for this mission.

Jesse Carpenter: Bill was there a turning point for you in the development of Kepler?

William Borucki: For a long time, when I talked to people they said it couldn't be done. There's just no way you could do this Bill. And when the opportunities came up to propose this, I was rather reluctant to propose this because I knew I had to fight the whole world that didn't believe you could do it. Then Dave Koch and others joined the team and said, "I believe, well let's do this together." And as we have assembled that team, each person's saying, "I've got some specialized expertise, I can help you." It has really come together. And that has allowed us to stay focused, because each person knows what the goal is, and they help each other stay focused on that goal. But that was a turning point, basically when Dave Koch came in and said, "I'll help you with this," because there was a tremendous amount of opposition at first. Since we hadn't proved we could do automated photometry, we hadn't proved there were such detectors, so it was a big help. And of course, as the team came together, we looked at many, many different possibilities, that we thought we would like to try, and we dismissed them all. We basically said this will be a very simple, very straightforward mission, it will do only one thing; find earths. And so we pushed aside all the other things that we, we enjoyed talking about, but we decided we would not ask to do.

David Koch: Our industrial partner Ball Aerospace has been very supportive the whole time. They've contributed a lot from their corporation and they really did a magnificent job in engineering and designing this thing. It is a marvelous machine that really holds together very nicely. It's very well integrated, the spacecraft itself wraps around beautifully around the base of the telescope. It really gives you goose bumps to see the flight hardware sitting in the clean room, and saying, "This is real. It's going to happen. This is our experiment, it's for us to make these discoveries, it's for us to write these new chapters in textbooks." It really is a thrill.

William Borucki: And of course, one of the things this came about from, was there was an article written in a journal in the 70's by a neurosurgeon, a fellow named Rosenblatt, Dr. Rosenblatt who said transit photometry ought to be something people should try and people should look into. And he did some calculations to show that it might work. Unfortunately for him, he then decided to go on a canoe trip and he drowned. And so for something like twenty years nobody took that up, until we came along and said that is a good idea, we can make that work. And so, it'd be rather wonderful if he'd still around to see the original idea he originally proposed come to fruition. Another person that shouldn't be forgotten is a fellow named Alex Wolszczan. He, with a post-doc was looking at radio stars, pulsars, and he started picking up a signal that varied in a systematic fashion. At first they thought, "No that must be little green men, there's something talking to us, a signal from space." But, looking very carefully they found no, that's not true, that star had some planets orbiting around it. And that star was basically a white dwarf, a star that had lived its lifetime, blown off its atmosphere and was basically a cooling ember, and yet it had planets around it. So he was one of the first people to actually find these planets before we found the giant planets. And so people said, "That's very unusual, of course when a star explodes like that, you don't expect it to form planets." So, if you could form planets that way, you certainly ought to be able to form planets the easier way, which is when you're forming the star itself. And so I think that also encouraged us to believe, if you could do it then, most stars will probably have planets.

Jesse Carpenter: Is there one thing that is most exciting or inspirational for each of you about this mission?

David Koch: Well, for me, just finding another Earth, something that is the same size roughly, so that you can have an atmosphere, the same temperature so you can have liquid water, it just boggles the mind to be able to say I know that that star up in the sky has another planet that could be similar to Earth. Nobody knew that before. People for eons, eons meaning thousands of years have wondered, "Is there another Earth? Is there another place like this somewhere else in the cosmos?" We're going to find that out in the next few years.

William Borucki: We're also going to be able to tell whether we want to develop Star Trek or not. If we find lots of planets, there's someplace for Star Trek to go to. If there isn't, we don't find any planets; that's all gone. That dream is gone. So, we should come up with a rather interesting answer in terms of what humankind will do in the future. Will it go out and explore the galaxy, because there's probably life out there, and planets with advanced life, or will we stay at home.

Jon Jenkins: It's extremely humbling. I have to share the observations these gentlemen have made. Out in the backyard when I was a kid looking up at the stars, in the grass, wondering whether those were campfires up there with other campers around them for us to potentially talk to, exchange ideas and information with, or whether we're the only ones roasting marshmallows around our particular campfire.

Jesse Carpenter: I'd like to thank our guests Bill Borucki, David Koch and Jon Jenkins for joining us. I'm Jesse Carpenter and you've been listening to a podcast from the NASA Ames Research Center.
 
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