A Telescope Fails, but the Hunt for Exoplanets Continues
Friday, August 23, 2013
The ailing Kepler planet-hunting telescope cannot be fixed, the victim of failed reaction wheels required to aim the instrument. However, researchers still have reams of data to sift through. William Borucki of NASA and Joshua Winn of MIT discuss the search for distant planets.
IRA FLATOW, HOST:
The Kepler space telescope was launched in 2009 and since then it was...wow, it's been working very hard. It has found over 130 planets orbiting distant stars with a few thousands possibles. But now Kepler is caput. It's broken and NASA says it can't be fixed. Does that put a hold on the search for exoplanets? William Borucki is the principle investigator for the Kepler mission based in NASA Ames Research. William, welcome back to the program.
WILLIAM BORUCKI: Thank you. I'm delighted to be back.
FLATOW: You have been called the visionary behind this mission. How upset are you about all of this?
BORUCKI: Well, the mission has certainly been a spectacular success. We have, you know, some 3500 candidates, 130 confirmed planets, many as small as that of the earth in our candidates. So I'm really delighted with what we have found. And, in fact, we have not analyzed all our data yet and that's where we expect to find the smallest planets like that of the earth inhabitable zone.
So I'm really satisfied with what the mission has done for us. I'm delighted with what we've accomplished so far. And I believe that we're going to find more earth inhabitable zone as we look through this date in the next few years.
FLATOW: Let's just talk about what happened to the Kepler.
BORUCKI: Well, the Kepler was designed to operate for four years. It operated successfully for four years. But then in July of last year one of the reaction wheels failed. And we have four reaction wheels and they're used to hold the spacecraft pointed at a single group of stars, 170,000 stars. And we don't want to miss any transits. The method works by looking for planets crossing their stars so the star gets dimmer for several hours.
So we look at the same group of 170,000 stars and what allows us to get that kind of precision is to hold the targets very, very steady. So when one of the reaction wheels went out, we still had a group of three and you only need three. The other one was sort of a spare. Well, that worked very well, we got more data. But as of May this year another wheel failed. And that means we can no longer hold steady on the targets. And so the data taking has stopped.
Now we're hoping that with two wheels we will be able to build an alternate mission. And so people from the science community are writing in ideas. You know, what can we do with only two wheels? The precision won't be as great but we'll be able to do something with it. And we're trying to figure out what is it we can do.
FLATOW: All right. Maybe our listeners can help you. Our number is 1-800-999-8255. We're talking with William Borucki who is the principle investigator for the Kepler mission. We're also Tweeting at scifri at S-C-I-F-R-I. We're going to take a short break, come right back. Maybe you've got an idea for how to continue this mission with Dr. Borucki. Stay with us. We'll be right back after this break.
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FLATOW: This is Science Friday. I'm Ira Flatow talking with Dr. William Borucki, principle investigator for the Kepler mission. He's based at NASA Ames Research Center in California. Why is Kepler not fixable like the Hubble telescope was?
BORUCKI: Well, the Hubble telescope is orbited around the earth. The Kepler mission is an orbit around the sun, so it's 43 million miles away. And there's no way for us to get out there and repair it. So basically what we're going to have to do is use what we have. The telescope is perfectly fine. The instruments are fine. We just need to find missions to use that to get new kinds of science.
And there's a lot of ideas as to how we might use the spacecraft with the two wheels to look, for example, asteroids or comets that are coming toward the earth or maybe super nova in the galaxy. We might look at microlensing objects which are, again, planetary systems, but very, very far away. And we have some ideas as to how possibly to look for smaller planets around some of the cooler stars. So we're looking at all these possibilities to find out what we can do with the mission in the future.
FLATOW: Yeah, they're always talking about looking for the asteroid with our name on it. Could Kepler be put into that search?
BORUCKI: Well, what it could do is look near the sun. So when asteroids and comets come around the sun during the day time we might be able to help there. But there are other ways of doing that and, you know, we could do that. It's just we're not sure it's the best use of a telescope.
FLATOW: Yeah, so...but you haven't defined exactly what the best use is yet, have you?
BORUCKI: That's right. We're getting ideas from people, getting ideas from the science community. And we'll be putting that together in the next few weeks and then coming up with the best proposal. What is the best use of that telescope? And then we will propose that to headquarters to see if they will fund it because without their funding, of course, the mission will simply be...the observation will be turned off completely.
We do expect to continue to analyze the observations we have, which of course will tell us more about the small planets inhabitable (unintelligible) stars. But getting new observations, that's something headquarters will have to decided, whether there is a worthy proposal that they can fund.
FLATOW: You're talking money here.
BORUCKI: Of course.
FLATOW: And we know how tight money is, especially for NASA now.
BORUCKI: That's right. So we try to make it the very best use of whatever funds are available. And of course there are other missions and they're good missions. And so NASA headquarters will have to decide where the limited funds go.
FLATOW: Let's go to the phones. Let's go to Mark in Tampa, Florida. Hi, Mark.
MARK: Hi, good afternoon. I'd like the science community to look forward a little bit. My suggestion is that everything launched into space have a reserve fuel component so it can station keep, that a robotic tug be invented and a common capture tool be applied to everything sent into orbit. So that tools like this could be returned and refurbished or at least not become space junk.
You know, we have everything common from electrical plugs to wire components. Why doesn't the space community, science community make these tools retrievable? The shuttle could've done it. A robotic tug can do it in the future. This is no great mystery. Let's not throw this stuff away.
BORUCKI: So your question is really why we haven't done it in particular. Well, this mission is orbiting the sun. So it doesn't come back near the earth for about 49 years. And there's no way of getting out there. It would be more expensive to get out there. And how would you catch up to it? It's already traveling several thousand miles an hour. Your rocket wouldn't travel any faster than that. So it really wouldn't catch up. So there are missions like ours that basically you can't fix when they get into orbit.
FLATOW: I think what Mark was suggesting that in future missions you design them so that they can be retrievable and repaired and design some way to get there.
BORUCKI: Well, the space (unintelligible)...
FLATOW: It's sort of like that common...
BORUCKI: ...faster than any rocket that we have so that's hard to imagine. But certainly in the future that might happen. We don't like that.
FLATOW: Yeah, (unintelligible) like that. Let's go to the phones again. Let's go to Bill in Columbia, South Carolina. Hi, Bill.
BILL: Hello. Good afternoon. My question is whether the disabled satellite could take over some of the tasks of the better-working, newer, more modern satellites similar to the way a file server in a computer network works. And the tasks which fall within its current abilities be sent to it and not be using the time of the newer better satellites and just send to it the tasks that fall within its capabilities. And it in turn sends its findings to like a central database or file server which then sends that what it found to a satellite which is capable of doing the more precise aiming or focusing or whatever.
BORUCKI: Well, it certainly sounds like an interesting way of doing things but right now we don't have that capability. What we're trying to do is use what we do have to do some of the measurements in some sense you're talking about. For example, there's going to be a satellite launched called Tess and it's going to be looking for planets around very cool small stars. And it may be that Kepler can help in that task.
There has been a French European satellite called Carro that has been looking for planets. And we may be able to do some help there. So there's a number of possibilities. But the satellites when they're designed, especially the NASA satellite, they're not like communication satellites and that they're very, very special purpose.
So an HST, for example, looks with extreme detail deep into space. Most satellites like Kepler look at a very large field view, 10,000 times larger than Hubble space telescope. But they're looking for fuzzy images. They're trying to measure their brightness. So each of these satellites is designed to do one thing, some breakthrough science, science that has never been done before. And so they're really quite different, one from another.
FLATOW: So this was only designed to last for four years, this satellite?
BORUCKI: It was designed to last for at least four years and it's fueled for about a total of maybe nine years. So there's still plenty of fuel aboard.
FLATOW: Yeah, but so why didn't you throw another backup wheel on there?
BORUCKI: Always what you try to do is keep the cost of the satellites within your budget. That's extremely hard to do because there's always a surprise. We have found all sorts of surprises when we've developed our mission things, cost triple what they were really priced to be. So to keep the cost down you don't do anything extra. You don't carry anything extra. But the wheels come in pairs so that was a marvelous thing, because that meant we had four wheels. And when the first one quit we still had enough wheels to run on. But having a completely new set would've cost...you know, increased the mission costs and we simply couldn't do that.
FLATOW: With the wheels going one after another, do you suspect there might be a design flaw in these wheels?
BORUCKI: The wheels went several billion revolutions, which is pretty impressive. But certainly they ought to be able to do better than that. Now sometimes some of those wheels do much, much better than this. So maybe there was a grain of dust or something wrong with the design or some detail. We simply don't know. And we have talked to the experts and everyone's puzzled as to what actually caused this difficulty and how we could avoid it in the future.
FLATOW: Yeah, you know, because you look at the Rover's on Mars designed for, what, three months. They're going on ten years, you know, something like that.
BORUCKI: Yes. We're quite aware that we went...I've gotten much...you know, increase the science value of this mission had at least one more of those wheels continued to run.
FLATOW: Yeah, you know...
BORUCKI: But they did their...they ran through their design. We got the data we asked for.
FLATOW: Well, you're a good soldier because I'd be madder than heck if it happened to my satellite.
BORUCKI: Would you be madder when you realized that you've got 3500 candidates, planets from the size of the moon to better the size of Jupiter, around all kinds of stars? We have so much data it's going to take a decade or two decades for us just to go and do the ground-based follow up to prove they really are planets. So I'm really delighted with what we have found.
FLATOW: Yeah, you have a good point. you have a good point. In fact, you did a great Segway for me because my next guest is Joshua Winn who is an associate professor of physics at MIT who is someone who specializes in using that Kepler data. And this week he published papers about finding planets very close into their suns, close as in 8.5 hour year. Wow. Welcome to Science Friday, Dr. Winn.
JOSHUA WINN: Thanks for inviting me.
FLATOW: So there's a planet that goes around its sun in eight hours...eight-and-a-half hours?
WINN: Exactly, and that's not even the closest one that we found. The current record-holder so far as we can tell goes around the star once every four-and-a-quarter hours.
FLATOW: How does something stay in a planet when it's spinning around?
WINN: Well, that's the interesting thing is that this really close-in planet is so close that it just barely avoids being torn up by the gravity of the star.
WINN: Usually when we detect a planet using the Kepler data, we can tell how big it is but we have no idea what it's made of. But in this case we actually can because if it were just made of rock it would've been torn to shreds. And just the fact that it exists means it must be mostly made of something denser like iron.
FLATOW: So it must be a little misshapen, then, would it not be, as it's going around?
WINN: Only slightly. It would probably be out of - not a perfect sphere but it's not something that we can detect directly.
FLATOW: Mm-hmm. How do you prove to yourself that really a transitioning planet is there and it's not some glitch in your data?
WINN: Well, we're really - so we were very interested in finding planets as close as possible to the stars, not only because we were just interested in whether nature makes such objects, but because they're actually - it's actually easier to tell that they're definitely planets. Part of the reason is that the technique is based on eclipses. Every time the planet comes around, the planet blocks a little bit of the starlight and we can register that with the Kepler telescope.
Well, if the orbit is only four and a quarter hours, you gets tons and tons of those eclipses over the fours years of the Kepler.
FLATOW: Oh. So Dr. Borucki was telling us he had to take a decade to go through all the data they've found already.
WINN: I think that's probably right. It's true that our community has just suffered a great loss with the loss of the Kepler satellite, but it's also true that it's left us this great inheritance of data that we can enjoy sifting through for the next decade.
FLATOW: Mm-hmm. What - if you were to build it again - Dr. Borucki, if you were to build this machine again, this satellite again, how would you do it differently or--?
BORUCKI: The first thing I'd do is add some extra wheels.
FLATOW: All right. I feel vindicated.
FLATOW: Some extra wheels. And would the optics be different or the way - you know, usually stuff that's in space is many years old because it's been tested for so many years.
BORUCKI: The optics are a fine design. I think we'd probably copy those. We might make some very minor changes but that's - the biggest changes would probably be in the electronics. Today we know much better how to build the electronics that would allow us to get this kind of precision. So there would be a change in electronics.
There'd be an addition of some wheels. But I don't think there'd be many other changes.
FLATOW: Yeah. Dr. Winn, tell us about TESS, T-E-S-S.
WINN: I'm glad you brought it up. So TESS is an acronym that stands for the Transiting Exoplanet Survey Satellite and in some ways it will be the successor of the Kepler mission. It's going to look for planets that eclipse their stars just like Kepler did but with one big difference. For practical reasons, Kepler focused on a particular part of the sky, a patch that's in the constellations of Cygnus and Lyra.
And in order to get enough stars for a meaningful survey, they had to look at some fairly far away, and therefore faint, stars in that patch of sky. And that means that as much as we love Kepler sometimes we get stuck because we see a planet going around a star but the star is so distant and faint we can't take the next step and train our biggest ground-based telescopes and learn more about the star and the planet.
WINN: TESS is going to be the opposite extreme. It's going to look for planets around the brightest stars all over almost the entire sky. So it'll use a smaller telescope and the data won't be quite as good, but once we find the planets they're going to be much easier to study.
FLATOW: I see. And is it fully funded and ready to go?
WINN: It was approved last April and NASA has committed to a launch in sometimes between four and five years from now.
FLATOW: How do you convince Congress to give NASA money for projects that it doesn't see any practical value for?
WINN: That's a good question. These projects are expensive. And we know there are a lot of other meritorious things that could be done with the money. We just have to...
BORUCKI: But also, when you think about it, the public is interested in exploring space. It's interested in is there other life out there. And these series of telescopes help us determine that. They - to, you know, a few years back people didn't know there were other planets or other planetary systems.
BORUCKI: Now we know there are. Now we're trying to find with TESS the closest ones. There will be telescopes and spacecraft that will look at TESS to see if we can understand the atmospheres of these planets. So I think the public is very, very interested in this kind of research.
BORUCKI: And so I don't think there's really a problem with getting Congress and headquarters to support such discoveries.
FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR. Talking about studying other planets. Theoretically, how close can you find an exoplanet, do you think?
WINN: To its star?
WINN: Well, four and a quarter hours is the record holder that we've actually found, as I said. You wouldn't expect them to be any closer - much closer than that because even a solid ball of iron would be torn apart by the gravity from the star.
WINN: So we're still looking but I would be really surprised to find something much closer than that.
FLATOW: And how big a sun is this compared to ours that you found?
WINN: Well, there's - we've actually found about a hundred of these. We were trying to answer the question of how close can planets be to their stars and so we thought of a way of searching the Kepler data quickly for planets that go around in less than a day. And we've turned out about a hundred examples.
FLATOW: And why would they exist? What brings them into that orbit?
WINN: That's what makes it really interesting, is we have no very good theory for how they got there. It could be that these were once giant planets that mostly made of hydrogen and helium, but all of that gas was blown away because of the intense radiation from the nearby star. Or it could be that these are more normal Earth-like planets that for some reason spiraled in towards the star and were captured into these tiny orbits.
FLATOW: We don't like to hear that.
WINN: Well, that's our agenda for the next few years, is trying to figure that out.
FLATOW: Too many "Twilight Zones" about that. So we don't want to...
BORUCKI: Well, Josh makes a good point. There's some idea that when a planet is close to a star like this, it raises a tide on the star. If the star is rotating more slowly than the planets orbiting the star, then it can draw the planet and it can take energy from that planet. That planet will basically go into a death spiral and finally be sucked into the star. We may be seeing some of that in what has been discovered.
FLATOW: Mm-hmm. And what would you like to do, Dr. Borucki? What's your agenda now?
BORUCKI: The agenda is finish the analysis of the data. In particular, we'd like to know are Earth frequent or rare?
BORUCKI: And if they're very frequent, around what kind of stars? Now, we're talking about small planets, planets that reside in the habitable zone. And the reason that's so important is these Kepler and tests are steps in the exploration of our galaxy. And the next really big step after TESS is going to be measuring the composition of the atmospheres of Earth-sized planets. Do they have water vapor and CO2? If they do, they can have life. They can have plants.
Do they have oxygen? In which case, they can have animals.
FLATOW: All right. Well, stay with us. We'll come back and finish that thought after this break. William Borucki and Joshua Winn. So we'll be right back. Stay with us. I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.
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FLATOW: This is SCIENCE FRIDAY. I'm Ira Flatow. We're talking about finding tiny little planets around other stars. Our guests are William Borucki, principle investigator of the Kepler mission at NASA Ames and Joshua Winn, professor at MIT.
I really interrupted you, Dr. Borucki, when you were talking about the next steps. And you were saying that after you find these exoplanets you'd like to see if they have an atmosphere.
BORUCKI: That's right. We'd like to get the composition, to find out whether perchance there are any pre-biological signals or any signals that would be indicative of life. And of course, when we find these planets they may be different compositions, different sizes. They might be water planets. You know, we'd like to try to look at whether they're ice covered or desert covered or whether they have oceans.
And with the bigger telescopes of the future we should be able to do that. And of course, beyond that we'll be trying to understand the life that might be there. You know, we have water planets; maybe they're just - can you imagine what water planets might have in terms of life? Our oceans are full of life, the strangest kinds of life that you can imagine.
What would those oceans be like? You know, so we're really moving step by step towards the exploration in our search for life. Another aspect, however, of why we do get good support, I think, from the public and from NASA is that when we do this we're developing new technology and that technology basically helps the industries in the U.S. and generates jobs.
And when we build these missions that push the state of the art, we're having companies build that and their engineers attack these problems. And they can use that information for a lot of different kinds of inventions and new products. So there's a lot of reason for us to continue this search for life because it's not only intellectually satisfying, but it's also satisfying respect to your pocketbook.
FLATOW: Mm-hmm. Dr. Winn, do you think that that's a convincing argument for the public or for Congress?
WINN: I think so. One of the reasons I feel blessed to be working in this field is that the public is genuinely interested. And they do sense that this is the continuation of our long history of exploration to find other worlds, some of which may be very similar to the Earth, some of which may be different in ways that we didn't imagine could be possible.
FLATOW: But Congress, you know, when you talk about going into space, they're talking about going back to the moon. That was the last thing I heard.
BORUCKI: Well, think about that for a moment. When you send out astronauts into space, they represent us. You know, we have a real contact with them. I mean, intellectually emotional contact.
BORUCKI: The last thing we want to see them is be injured or die. And consequently, if you go to Mars, a rescue mission is essentially impossible. But if you go to the moon and you learn how to live in space with the kinds of resources that are available, you've got a real opportunity there if something does go wrong to mount a rescue mission to them and bring them back safely.
So that a lot of the effort in these ideas is to make sure that when we do something in space those astronauts survive and prosper and teach us a lot and don't basically get harmed by it.
FLATOW: Mm-hmm. Well, you know, history is replete with explorers who were that concerned about coming back. They wanted to go out and find those new frontiers. You're saying that we live in a different age now.
BORUCKI: I think there's a couple of areas here. You can imagine what NASA does, which is this basic exploration. But ultimately when you're settling the moon or settling Mars or whatnot, that's probably something that will be done in private. And they have, I think, options to take more risks than a government organization might.
FLATOW: Mm-hmm. Very well put. I thank you both very much for taking time to be with us today. Fascinating.
WINN: Thank you.
FLATOW: You're welcome.
BORUCKI: Thank you.
FLATOW: William Borucki, principle investigator for the Kepler mission and Joshua Winn, associate professor of physics at MIT.
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