Planetary Radio: Space Exploration, Astronomy and Science - Kepler Begins Search for Other Earths

Episode Date: May 11, 2009

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Music Kepler looks for other Earths, this week on Planetary Radio. Music Hi everyone, welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. the final frontier. I'm Matt Kaplan of the Planetary Society. Bill Barucki says his new sharp-eyed spacecraft has what it takes to discover Earth-sized planets circling other stars, and that some of them may be in just the right place to support life. We'll talk with Bill as Kepler begins the hunt. Bill Nye says keep an eye on the X-37 this summer. It could help us replace the space shuttle.

And Bruce Betts will have his eye on the night sky as he fends off aggressive reindeer in this week's What's Up. Emily Lakdawalla is on maternity leave and doing just fine. Space shuttle Atlantis may be on its way to the Hubble Space Telescope by the time you hear this. It's the fifth and final repair and upgrade visit to the great instrument. Meanwhile, back down here on Terra, the Obama administration has issued a proposed budget for NASA that would boost Earth and space science, robotic missions around our solar system, and the new Ares-Orion human spaceflight system. You can get the Planetary Society's take on the budget

at planetary.org. Here's Bill. Hey, hey, Bill Nye, the planetary guy here, vice president of the Planetary Society. And this week in space news, at least in the United States, everybody is still bent out of shape that the space shuttle is going to be retired. When the space shuttle is going to be retired, When the space shuttle is going to be retired, 6,500 people are going to be laid off in Florida. This is a bad thing. But my friends, the space shuttle has to be retired. We can't keep flying it forever.

It's 30 years old at least, and it's caused some trouble. It's a couple of bad wrecks. In the meantime, in the background, I remind us all that the X-37, which is a test vehicle tested this summer. And it's the next thing after the space shuttle. It has a payload of about five tons. That's a lot of stuff. And it's got stubby little wings. It enters at Mach 25 and it comes and lands. This is the future. We got to be thinking about the future. The space shuttle is the past. Now, whether you want to support human space exploration and missions in low Earth orbit or missions out to the Lagrange points, these gravity balance points far from Earth, or whether you want to put more hardware up in space,

whether you want to take hardware down, declutter the orbits, all of this takes new vehicles, new spaceships. And the X-37 is that thing. There's going to be hardships as we change from one style of spaceship to another. But what else are you going to do? We can't be obsessed with keeping this thing running that's caused so much trouble. And, of course, it's a bit of a financial burden. Keeping an old ship like that running takes a lot of money. We can do better.

Let's think about the future. Let's move forward. The X-37 is going to fly us into the future. And if it's not the X-37, it'll be something new and cool. Thanks for listening. I've got to fly. Bill Nye the Planetary Guy. It has been barely two months since the launch of the Kepler Planet Finder,

yet the spacecraft has already returned a beautiful first light image. William Barucki says the mission is well on its way to finding exoplanets that are the size of our home planet. Some of these may be found in that not-too-hot, not-too-cold region called the habitable zone. Berucki is the science principal investigator on the mission, which will steadily watch one stretch of sky for at least three and a half years. The spacecraft has a single instrument that looks like a camera, but is actually a photometer. This 95-million-pixel CCD detector is purposefully kept slightly out of focus, which helps it do its job of looking for tiny changes in the light of about 100,000 stars.

Bill Berucke talked with me from NASA's Ames Research Center in Northern California, where he has worked as a space scientist for 47 years. Bill, thanks for joining us on Planetary Radio, and congratulations on not just first light for Kepler, but a pretty spectacular image at that. Yes, it's wonderful. It covers a huge area of sky. The detectors are all working. It's marvelous to see all those stars. 4.5 million stars?

That's right. There are 4.5 million stars on the active detector area. There's even more, of course, in the areas between the detectors and around the detectors. But there are 4.5 million stars that will be something that we could make measurements of, although we only select about 150,000 of those stars. Basically, we pick the stars that are bright and more or less like that of the sun. Some of them are a little bit hotter. A number of them are cooler than the sun, but basically like the sun. Not the giants or the stars that have evolved off the main sequence

and are not likely to have habitable planets. You were a pioneer in developing, laying the groundwork for the technique that, as I understand it, Kepler will be using. Can you talk a little bit about this transit technique? Certainly. The transit technique is quite different than the radio velocity technique or the wobble technique that's been so helpful up to now. The transit technique works especially well for small planets. It does big ones as well, but the radio velocity system really needs massive objects. So Jupiter, Saturn, Neptune work very, very well.

Earth, very, very difficult. With the transit technique, basically you're looking at a large number of stars simultaneously, and you're looking for a planet to cross its star. So you're measuring the brightness of every one of these stars every 30 minutes, asking, does it dim because the planet crosses? When a planet crosses, the amount of light that's blocked tells you how big the planet is. And so you can tell rather quickly, you know, if the blockage of light is 1%, then the planet's about the size of Jupiter or Saturn. But on the other hand, it's only a tenth of a percent, then it's probably a Neptune or Uranus-sized planet. When it comes to Earth or Venus, we're talking about a hundredth of a percent, a hundred

parts per million. So you've got to measure these very tiny changes of light if you're looking for planets like that of Earth, and we are. And so we have a technique that allows us, with a large group of CCD detectors, to measure over 100,000 stars to look for that change in brightness. Now, when that happens, it happens for about 10 hours, and then it stops. You know, the planet's moved across the star, and when it comes back around on a spectral orbital period, it does it over again. So we look to measure the orbital period as well as the size of the dip. And if the orbital period's short does it over again. So we look to measure the orbital period as well as the size

of the dip. And if the orbital period is short, the planet's close to its star. If it's very long, it's far away from the star. And we can calculate, knowing the mass of the star, the temperature of the star, in Kepler's third law, given the orbital period, we can tell how far away it is from the star. If we measure the temperature of the star, the size of the star, we can tell whether the temperature is right on that planet to be in a habitable zone. We use those measurements to determine whether or not that planet might be in a habitable zone of its planet, its star, and whether it's inside the habitable zone, further out.

Basically, we learn as much as we can about that planetary system. further out, basically learn as much as we can about that planetary system. Does that explain why it's so important that Kepler do this work for at least three and a half years? That's right. We're looking for not just one transit, but many transits. We need a minimum of three. The first two transits give you the orbital period. The third transit gives you another measurement of the orbital period. The two should agree. It's about a part in 100,000. That says it's an object orbiting a star. It's not a spot on the star. Spots on stars are as big as Earth. That kind of noise is always there, but those spots move across the star in periods generally of weeks or days. And so measuring the orbital period, seeing that it repeats, says this

is not a spot. It's something extremely periodic. You have got an object orbiting a star. Now, it may be that it's not a planet. It could be a small star. So we're going to have to determine, after we see these transits, are the objects orbiting that star planets, or are they small stars? So there's another program that works with Kepler. It's the same telescopes that do radio velocity. Jeff Marcy and Bill Cochran and Dave Latham are people who use these big telescopes. They follow up our discoveries, and they measure the mass of the secondary object. And they can tell, is it a small star, or is it a planet? So we all work together. The team has about 30 people on it in the United States alone to go and detect these candidates, check their

orbital periods, and then go to measure the masses so we're sure it's a planet, not something else. You know, we just had Deborah Fisher, who of course works with Jeff Marcy up there in Northern California, not far from you at the Ames Research Center, talking to us about how their terrestrial work is going to back up what you discover with Kepler. Why is it that Kepler's work is best done in space, not just in Earth orbit either, but way out there? That's a good question. The radio velocity work, the wobble work

from the ground-based telescopes works quite well. And it doesn't need to be in space. But when you say, I'm going to measure the brightness of a star, I'm going to look through the Earth's atmosphere. The clouds, the dust, and the day-night cycle stop you from doing a good job.

Generally, if you could do a part per thousand in terms of measuring the brightness of a star, you're doing quite well. But we need to do a measurement now, an instrument measurement, about 10 parts per million. That means there can't be any dust in our way. There can't be any clouds.

The day-night cycle will stop us from following the transit during its entire duration. So we have to be in space to get away from the Earth's atmosphere. And when you're in space, you can look away from the sun constantly for 365 days a year so you don't miss any of the transits. So there's no day-night cycle for us. We can look constantly. The Kepler website, which we will link to, of course, from planetary.org slash radio, goes into great detail on how all of this work will be done and also makes some conservative estimates about what you might find. And I guess you must be, I hope,

that you're taking some hope, getting some optimism from the enormous successes that others have had in discovering planets and ever smaller planets. In fact, we talked about one just twice the size of Earth last week on the show, except that it's way, way out of the habitable zone, way too close to the sun that it circles. What we do to try to calculate what we might expect to find is we look at the capability of our instruments, and then we look at what's out in space that we'll be looking at. So over the last five years, we've looked at those 4.5 million stars,

and actually more, and we've measured their brightnesses, we've measured their temperatures, we've measured to find out whether what we call the local gravity is high or low. And if it's a dwarf star like the sun, the gravity is very high, and we can say, this is a star something like the sun. It's a small star burning hydrogen. And we can tell from the giants, which of course exhausted most of their hydrogen, and have now expanded. And they're so big, it's hard to find a planet around them. And they're so big, they often incinerate their planets. We know what we're looking for. We know

how many stars are out there. And so we can say, well, with this instrument, what could we find? That's William Perocchi, science principal investigator for the just-launched Kepler Exoplanet Finder. He'll tell us more about the mission in a minute. This is Planetary Radio. I'm Sally Ride. After becoming the first American woman in space, I dedicated myself to supporting space exploration and the education and inspiration of our youth. That's why I formed Sally Ride Science, and that's why I support the Planetary Society. The Society works with space agencies around the world and gets people directly involved with real space missions. It takes a lot to create exciting projects like the first solar sail,

informative publications like an award-winning magazine, and many other outreach efforts like this radio show. Help make space exploration and inspiration happen. Here's how you can join us. You can learn more about the Planetary Society at our website, planetary.org slash radio, or by calling 1-800-9-WORLDS. Planetary Radio listeners who aren't yet members can join and receive a Planetary Radio t-shirt. Members receive the internationally acclaimed Planetary Radio listeners who aren't yet members can join and receive a Planetary Radio t-shirt. Members receive the internationally acclaimed Planetary Report magazine.

That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. My guest is William Barucki, longtime space scientist at the NASA Ames Research Center and science principal investigator for the Kepler mission, now beginning its continuous surveillance of about 100,000 stars in the region of Cygnus. Bill has good reason to believe his spacecraft can achieve its goal of finding Earth-sized exoplanets in the habitable zone,

even though that zone will vary from star to star. Put a planet the size of the Earth around all these stars in their habitable zone. So we know what a habitable zone is because we know the mass of the star, we know the temperature of the star, and so we can say for the cool stars, the M dwarfs, oh that has an orbital period of a month. Or if it's the stars that are a little bit higher temperature than that of the sun, like the F dwarfs, we say, well, that orbital period is of the order of a year and a half. So put a planet there and ask, how many would you see? How many orbits would line up on a statistical basis?

And the answer is, for planets like the Earth, we ought to be able to see something like 50 of them, if most of these stars have a planet in the habitable zone. Now, clearly, stars or planets that are bigger than the Earth, say twice the size of the Earth, could still be habitable if they're in a habitable zone. They're easier to find. And so we find we ought to see something in the order of a couple of hundred of those if most of the stars have a planet in the habitable zone.

Well, we expect that some of them will, but some of them will have planets like the Earth closer to their star or further away. How many would we find in that case? And again, our instrument is capable of finding several hundred if most such stars have these planets. So at the end of the mission, at the end of three and a half years, we ought to be able to say, oh, we found a lot of planets. They have these kinds of size distributions. Some are small like Venus or Mars. Some are twice the size of the Earth. So we have a distribution of sizes. We have a distribution of how far away are they from their star? What fraction of the habitables? We'll have that information. And of course, if what we find is the opposite,

if we're surprised, and most stars don't have these planets, we'll know that too. And of course, that will be the biggest surprise of all. But nobody's sure of what we'll find. And what we have certainly, year after year, have found is that we're always surprised. We always believed that Jupiter

would be out at five astronomical units. We found many inside Earth's orbit, some inside the orbit of Mercury. It's a big surprise. We believed early on that the orbits would all be circular. In fact, most of them are elliptically, highly elliptical. And so we've always seen a lot of surprises out there. And so we're not too sure what we're going to find with respect to Earth, especially in the habitable zone. So everybody's very eager to get started, get this data, and get the answers. Always makes it more fun and exciting when the universe unloads new surprises on us. This spacecraft is going to play this very important role that you've been talking about. But it also seems to lay groundwork for missions to follow.

That's right. Kepler is the world's first mission capable of finding Earth-sized planets in a habitable zone and determining how frequent they are. If we find most stars have such planets, then follow-on missions make use of that information. If, on the other hand, we find very few Earths, then the follow-on missions have to be much larger and much more capable so they can look farther out into space to find enough targets to be useful. And so people have been talking about these successor missions,

have been talking about these successor missions, missions that could, for example, find, well, the composition of the atmospheres around these Earths. Do those atmospheres have water vapor? Do they have CO2? Do they have some oxygen? And that would be absolutely wonderful if they did. But those missions are much more expensive, much more difficult than Kepler. So Kepler is sort of a step in this direction. It's a forerunner. It's an explorer to find out what's out there so the next set of missions knows, you know, do we build a big coronagraph? If we do that, what we're saying is there's probably lots of Earth.

If on the other hand we find very few, then you don't build a coronagraph. You probably build a very large multi-telescope interferometer. So it's one step along the way as mankind explores poor life in his galaxy. And of course after the terrestrial planet finders approach, then there will be missions that follow that, even more capable missions of trying to

understand what's on those planets and whether there's life on those planets. So Kepler's one step along the way. A critical step, but one step. How are things going so far? How is the health of the spacecraft? It's been just wonderful. We had a great launch. We're in a right orbit, orbiting the sun. We have a period like we wanted, which is about 53 weeks instead of 52. So it's trailing the Earth, and we use that very well to transmit back the data. And it's shown us all the detectors are working. We're seeing all the stars we've expected. So it's really been great.

In the next week or two, we'll stop taking calibration data. We've already focused the telescope. The focus now looks good. We're measuring the geometry, how do the stars lay out on all the detectors. And we will shortly check what its precision is. That will be done this next week or two. And then we'll be going on to let's look at the target stars, let's get started, let's get our first data coming down, which will come down on a monthly basis.

Probably the first major data set will come down on June 18th. Well, good hunting, Bill. We're about out of time. How long before somebody up there at Ames puts out that first light image as a sort of contemporary art poster. That's available on the net right now. If you go to our website, you can download it already. And I want to mention that you've got other things online as well,

including a downloadable Kepler Star Wheel. That's right. We've got Star Wheels. We've got lessons planned for teachers. We've got explanations of the science. We've got explanations of how we built this system. And there's even a biography of many of the people who work on the team. There's a great deal of information on our website for anything you might be interested in.

And we will put up a link to your biography as well because it is fascinating because you've been at this for, boy, going on five decades now. And we want to congratulate you on this somewhat of a personal triumph, certainly a triumph for you and your team at Ames, where this mission is now being directed. That's right. And, of course, it's a triumph for all of mankind. We are carrying a CD with the names of almost 100,000 people who have signed up to be part of this mission. So it's really a triumph for all of mankind as we do, we start an exploration of our galaxy. Bill, I'll just say once again, good hunting and thanks very much.

You're welcome. My pleasure. Bill Barucki is the principal investigator for the Kepler mission, looking for Earth-like planets, not just Earth-like planets, but those that live in that Goldilocks zone, the habitable zone, that is just the right distance from a star, where water can be liquid and other conditions might be right for life. And we'll be looking, if not for life, at least for lively views of the night sky with Bruce Betts when Planetary Radio continues with What's Up. Got Bruce Betts on the Skype connection.

It's time for What's Up on Planetary Radio. He is the director of projects for the Planetary Society. He's going to tell us about the night sky and probably some other stuff. How are you doing? Reasonably moderately adequately okay. And you? I'm okay. I'm okay. I just enjoyed a little bit of a Mother's Day celebration, but you sound a little bit under the weather.

I am a little bit under the weather, not being a mother. Well, you're under the night sky, too. Can you tell us about it? He said cleverly. Just wanted to prove it. Why, yes. Yes, I can. In the night sky, in the the evening you can check out saturn it is below leo it's high in the south after sunset looking kind of yellowish pre-dawn sky it's just a planet party and if you look over in the east in the pre-dawn you can't miss jupiter looking extremely bright

kind of in the east or southeast even brighter brighter object to the lower left of Jupiter, but much lower down, is Venus, and the two are striking together. You might be able to see Mars just a little bit below Venus, looking kind of reddish, so it's a planet party. Let us move on to this week in space history. It was 1973 this week. Excuse me, do you have a reindeer in the room there with you? Sometimes. What did you hear? Nothing, nothing at all.

I'm sure it was just my imagination. No, I doubt it. There are dogs walking on a wood floor. Okay, there were jingle bells, actually. Ah, the jingle bells, that would be the scratching at the collar. Ah, okay, that explains it. I've never seen a reindeer do that, but I'd like to. Well, the flying ones do. Okay, they can do whatever they want, as long as they don't fly over. Okay. So this week in space history, there was a reindeer that was launched in 1973. No, there was Skylab.

Skylab orbiting space station launched in 1973. Well, that's good. That's significant. Well, yeah. Let us move on. We're going to try a meek random space fact. Oh, you poor boy. You know what? You're under no obligation to outdo yourself week after week.

You know, you can slide through, take it easy now and then. Thank you. That was kind of a slide. A little bit. Okay. All right. So in the sky, when you're checking out the moon, of course the moon goes through phases. Everyone knows that.

And some people may know this, too. the moon goes through phases. Everyone knows that, and some people may know this too, but depending on what phase it is, it's obviously telling us where it is in its orbit, which also correlates with when it's visible in the sky. In the case of full moon, it rises around sunset, sets around sunrise, and is highest around midnight, whereas new moon, not so much visible because it's at its highest around noon in the middle of the sky. But first quarter moon and everything where it's in a waxing state, so getting to larger phases as the days go along, you're going to see it in the evening sky. So like if you see a crescent moon and you see it in the evening sky, it's waxing. If you see it in the pre-dawn sky, it's waning,

so going to phases that have less light on the moon. You may have thought about it. You may not have, but now you have. And it makes perfect logical sense. Nice work. Stardate couldn't have done it any better. Thanks, I think. Although I'm sure there'd be some nice swelling music.

Yes, there would be. We'll save that for the end. Let's go on to the trivia contest. We asked you in 2009 what was the closest object, natural asteroid kind of object, to fly by Earth that we knew about. And it turns out there were two that were close enough that were willing to give the prize to people who answered either of them. How'd we do, Matt? And it was pretty well divided between the two that we would have accepted as a correct answer. The first of those being 2009 DD45. And you know what? I misplaced the other one. Do you have it handy there? It is 2009 EJ1. And both of these were in the roughly 40,000 miles out kind of distance.

So about twice geostationary satellite distance, or about 20% of the Earth-Moon distance. Big suckers, too. I read that DD45 was, you know, over 100. I think I read 115 feet. So what, about 35 meters? Something like that. Yeah, and they had some uncertainty on it. But yeah, ballpark tens of meters for that one.

So it would have been exciting had it hit. And hopefully this is going to be very exciting for Tom Hendricks, one of our regulars. Tom came up with Neo DD-45, good enough, or I should say 2009 DD45. That's good enough to get Tom a Planetary Radio t-shirt there in Quincy, Florida. He is a very faithful listener. And so, Tom, we are happy to send that out to you. And maybe an Oceanside Photo and Telescope Rewards card, too. I did want to mention Kevin Hecht as well, who also came up with 2009 DD45, but also had this thought about, you know, if we learn to deflect these guys, why don't we smack them into the moon and do a lot of cheap mining?

You know, sort of kill two stones with one, well, you know what I mean. Okay, then. I'll quit there. Thank you, Kevin, and thank you, Tom. All right, let's go on to our next trivia contest, and we're going to talk about things a little bit farther away. How far away, in light years, to a rough accuracy, is the Andromeda Galaxy, our closest really large galaxy friend?

Go to planetary.org slash radio, find out how to enter. You have until May 18th. That'll be Monday, May 18th at 2 p.m. Pacific time to get us that answer and win yourself a Planetary Radio t-shirt and an OPT rewards card. Great, thank you. You did a nice job getting through this. Thank you. I'm made so much easier by you, as always. That's a funny sound in reindeer.

Somebody doesn't like you kissing up to me. I think that's what it is. It's a Wookiee reindeer that's jealous. Well, put his chain collar back on him and make him go in the other room. Take a night, Bruce. All right, everybody, go out there, look up at the night sky,

and think about Wookiee Reindeer. Thank you, and goodnight. That's what I want, coming down my chimney on Christmas Eve. Bruce Betts is the Director of Projects for the Planetary Society, and he joins us every week here for What's Up. Half it up, fuzzball. A cataclysmic explosion lets us trek farther back in time than ever before. That's next week on Planetary Radio,

which is produced by the Planetary Society in Pasadena, California. Live long and prosper. Thank you.