Planetary Radio: Space Exploration, Astronomy and Science - Sara Seager and the Search for Earth’s Twin

Episode Date: December 16, 2014

MIT planetary scientist and astrophysicist Sara Seager is on a quest. She wants to find a warm, wet exoplanet with signs of life. It could be Earth 2.0.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Hello, dear podcast listeners. It has been a while since I last took the opportunity to thank you. I hope you agree that 2014 has been a great year for Planetary Radio. 2015 is looking even more exciting. All of us are delighted to have you join this weekly ride across the universe. We're especially grateful to those of you who helped create the show through your Planetary Society memberships and special gifts. Your end-of-year donation is the most powerful way to keep Planetary Radio strong, and it's easy.

To get started, click the big blue I Can Help button at planetary.org slash radio. Your gift will go directly to the show, helping us do even more in the coming year. A gift of $50 or more will get you a quiz-free Planetary Radio t-shirt of your very own. Thanks again for listening and for your support. We wish you the very happiest of holidays. Looking for Earth 2.0 with Sarah Seeger, this week on Planetary Radio. 2.0 with Sarah Seeger, this week on Planetary Radio. Welcome to the travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society.

Earth's twin is out there waiting for us to build the tools that can find it. No one is more involved in that quest than Sarah Seeger. She'll join me in a few minutes. The just-passed federal funding bill has generated controversy, but Bill Nye is celebrating one provision, and Bruce Betts will tell us about the holiday night sky on WhatsApp. We begin with senior editor Emily Lakdawalla. Welcome back, Emily. So Venus Express, not quite dead yet. Not quite dead yet, but really very close. So I was kind of sad as I was writing this update last week. Basically, the spacecraft has exhausted all of its fuel doing trajectory

correction maneuvers. And they were in the middle of a series of maneuvers designed to raise the orbit a little bit, keep it out of Venus's atmosphere. And then they briefly lost control of the spacecraft. They're in control of it now. It's talking with them. But it really looks like the fuel tanks are empty. And so in January, it's probably going to fall right into the atmosphere. Sad, of course, but still yet another mission that lasted far beyond what was projected. Oh, yes. You know, it's always sad to lose a spacecraft. But this one, we couldn't possibly be more proud of what it's accomplished during its long mission to Venus. And really having these long missions, we've gotten used to it. You've gotten used to spacecraft surviving so much longer than they were designed

to. And it's amazing the kind of science that you get out of a mission that lasts so long. With Venus in particular, since Venus Express was designed to look at the atmosphere of Venus and how it changed over time, being there for a dozen Venus years has really helped scientists understand how the atmosphere actually does behave differently from time to time. And they've been watching it thoroughly. All right. But with the departure of Venus Express, what, if anything, can we look forward to at this planet, which has often been called Earth's sister? Yeah, it's an important planet for us to study because it's so close to Earth, both physically and in terms of its physical properties. And Venus Express death will leave us with no active spacecraft there.

There is Japan's Akatsuki, which may be able to enter orbit late next year, late 2015. But even if it does get into orbit, it won't be the orbit it was designed for. It's got no main engine anymore. It had to vent all its fuel, try to get into orbit with its reaction control thrusters. Who knows if it's going to work or not? I wish them the best. But in the meantime, we really need to get another spacecraft in production in order to send it to Venus.

Hear, hear. Emily, I look forward to talking to you next week, and I hope that you'll be able to tell us some of the highlights of your visit to the annual meeting of the American Geophysical Union, the AGU, that you'll be heading for in San Francisco very soon, I think. Sounds like a plan, Matt. Excellent. Thank you again. She is our senior editor, the planetary evangelist for the Planetary Society and a contributing editor to Sky and Telescope magazine.

Up next, the CEO of that organization, Bill Nye. Bill, there is reason to celebrate in the planetary science, at least the planetary science funding community. Oh, yes. So the Cromnibus Bill, which is the combined continuing resolution, keep the government, the U.S. government open, and the Omnibus Bill, which is everything all at once bill, they got combined and they got passed in both the Senate and the House. Now, even if you're not from the U.S. and you're listening, it's a significant thing because it means that planetary science is going to get funded at a little higher level than it has been in previous years.

We're up now to $1.44 billion. And if you're scoring along with us, the Planetary Society, after careful analysis, Casey Dreyer, Bill Atkins, our lobbyist, and other people on the board of directors, the last couple of years, we've sought one and a half billion. So I got to tell you, in the world of politics, that is really close. Oh, yeah. And you're within only, Matt, only 60 million. Oh, that's pretty good. That's chump change. Well, it's a little more than chump change, but it means that we will be able to fund a mission to Europa. Now, Matt, I am a broken record. I'm a skipping CD. No, wait. I'm a digital recording put on replay. I got to say, everybody, if we find life on another world or evidence of life, it will change this world. It will change this world in a dramatic way. And this gets into

Bill's, I'm Bill, gets into my thing about exploration. Let's just go out there. I mean, we can argue about the instruments and how many they're going to be and how much he's going to cost, but let's get out there and just sniff around. I mean, if we found evident bacterial mats on Mars somehow fossilized, if we found something squirting out of geysers on Europe, I mean, it would change the world. And so this is a step in the right direction. And if I may just say, Matt, CEO now of the Planetary Society, four years. Four years. And we are really making progress.

I mean, people know us in the U.S. Congress and that we got an increase in what used to be kind of, if I may, an obscure line item in the NASA budget. It's really significant. I really feel good about this. And a lot of Congress people on both sides of the aisle saying planetary science, we're for it. Well, because it's where the new stuff's being done. You know, I mean, now Orion flew and that was a success. And that's really good.

That's really good. But planetary science is where we're making these extraordinary innovations. And I claim it's where you're going to find the great, amazing, significant discovery that's going to change the course of human history. Not that that's a big deal. So we got to 1.44 out of 1.5. That's really good, everybody. And even if you're not from the U.S., it's good for space exploration writ large because

planetary missions especially include other space agencies. It's an exciting time, everybody. Happy Isaac Newton's birthday week eve. Thank you very much, Bill. Thank you, Matt. CEO of the Planetary Society with a reason to celebrate this holiday season. He is Bill Nye, the the way. Casey also reminded me that there is still no official Europa mission. That's a commitment NASA is yet to make. Somewhere out there, perhaps not too many light years from Earth, is a smallish, rocky planet with liquid water on its surface. The trick is to find it.

That's the Quest MIT astrophysicist and planetary scientist Sarah Seeger has devoted herself to. It's also why she was at Northrop Grumman here in Southern California a month ago, where she could take a look at the James Webb Space Telescope and talk to the men and women who are creating that much more powerful follow-on to the Hubble Space Telescope. Sarah and I sat down in a Northrop Grumman conference room moments after she finished a great presentation. Sarah, thanks very much for joining us on Planetary Radio. Matt, it's great to be here. And it is great to be right here, too. I mean, this has got to be pretty exciting for someone like you who was just talking about what the James Webb Space Telescope may do for your job, for what you would like to

know about our galaxy. I mean, is it pretty cool to be here? Yes, it's amazing to be here and to be talking to the people working on the James Webb Space Telescope. And later on, I'm going to get a tour of some of the recent happenings. You'll love it. I mean, and you've said you've been here before. We had one of those. Quite a while ago. I was here a couple of years ago when it was not nearly as far along as it is now. Well, and I want to come back because it's much farther along than the last time I was here. But I'm going to envy you for one thing that I'll probably never have, and that is that you were just presented a piece of the JWST. Yes, a piece of the backplane. Pretty cool. Yeah, probably the most cool souvenir I've received. How many Earths are out there waiting for us? Well, you know, there could be so many that we

can't even count them all. We think that our own galaxy has hundreds of billions of stars. And we're starting to think that Earth-sized planets may be as common as 5 to 20 percent in the habitable zones of their sun-like stars. So there are billions and billions of Earths just waiting to be found. And we know this now thanks to the work of space gods like Kepler, especially, right? By the way, what do we owe Bill Berucki, the sort of father of that? We owe Bill Berucki for his perseverance. He worked so hard for many decades to make Kepler a reality. And Kepler delivered beyond everyone's expectations. Yeah, there were a lot of people who doubted that it would be capable of doing what he believed in. Well, initially people doubted,

but what's interesting is transiting planet as a discovery tool was really years or decades before its time. I mean, Bill's paper came out in the 1980s. That was before we had CCD detectors that we could actually use. And so really, it was the advent of the CCD detector that enabled people to believe that he could make the measurements he needed. So now here we are with all of these hundreds, well over a thousand planets, at least candidates now, right? Yes, we have at least a couple thousand planets that are validated as planets and a few thousand more planet candidates. The real search, of course, is to find those that are roughly earth-sized in that Goldilocks zone, the habitable zone. You had a slide that indicates that the habitable zone, our understanding of what it might be, has evolved quite a bit. Yes.

In fact, it's the diversity of exoplanets that motivated us. I think, honestly, we're going to get close to throwing out the habitable zone concept. And we're going to have to go case by case. Uh-huh. I mean, think about it. Venus is not habitable. But if Venus was much further from the sun, its greenhouse effect would then be an advantage. I know there's also talk now of, in fact, you covered a little bit of this,

that someplace scientists once thought, no, we wouldn't want to look there. We very much want to look at, and that's near red dwarfs? Yes. In fact, you know, before people were a bit biased about what we should and shouldn't look at. Now we're actually faced with the reality that we're only going to have a few really amazing planets to look at in detail. So that's why we've opened up our minds. If indeed the habitable zone ends up being much broader than we thought, you already threw out that 20% figure,

and you went on from that to a slide in your program, which I'll bring up this way. Does Frank Drake know you've solved his equation? Well, I haven't exactly solved his equation. I call it a revised Drake equation. I was kidding. Okay. Well, let me say something. It turns out that Frank Drake has a daughter named Nadia Drake. And Nadia Drake is actually a journalist. And Nadia Drake wrote an update, a Drake equation update named Nadia Drake. And Nadia Drake is actually a journalist. And Nadia Drake wrote an update, a Drake equation update for National Geographic. And she interviewed her dad. And she also interviewed me on this so-called revised equation. So I think he must know about it.

But he hasn't commented on it one way or another. Take us through this revised Drake equation, which actually you did end up with a number at the end. Yes. Well, the goal of the equation is, just like the original equation, to illustrate to people that we are embarking on a real quantitative search right now. And in this equation, it has several terms. The first few terms are quantifiable. We can measure those terms. The rest are and will always be speculative. So the first few terms are how many stars are accessible to, you know, given planet-finding technique. The example I was using is the TESS spacecraft to be launched in 2017. It's an all-sky mission to find transiting planets around all stars, but in particular small stars.

So I said all sky as opposed to Kepler, which has looked at a very small segment of the sky. And I put 30,000 stars available. The next term is what fraction of those stars would have planets in the habitable zone. We don't totally know the number yet. Reports come back anywhere from 0.15 to even maybe as high as 0.8. It's remarkable, really. So that's the second term. The third term is what fraction of those star-planet systems, when found, would actually be observable.

And for that one, I have to consider that transiting planets are rare. They're not really that common. As well that some of the stars that TESS will observe will be too faint to have their planet atmospheres followed up in the future with, we're thinking, the James Webb Space Telescope. So I put that one at 0.1%. And the final two terms are all speculative. Do what fraction of those planets in the habitable zones of those M stars, what fraction of them have life on them? And then finally, what fraction of that life would actually

produce a byproduct gas that could fill the atmosphere that we could observe with the James Webb Space Telescope? I mean, I've totally had to fudge the numbers. I didn't want to come up with zero or negative number. So I put all the numbers in place so I'd show you that if we're really lucky, that planets are common in their habitable zones of M stars, that life is ubiquitous. I put it at 50% and that if 50% of that life generates a spectroscopic gas that we could detect remotely, you know, we have a chance at having a few candidates. And I hope that you guessed low, of course, but I wouldn't, would you be surprised if you guessed low? I don't think I guessed low. I think thinking that half of all planets that could have life have life, I think it's pretty generous.

Optimistic. Optimistic, but we have to be. We want to be able to tell the world that we're so excited that our first chance is coming up to study rocky planet atmospheres in the habitable zones of their host stars. More from MIT's Sarah Seeger about the search for Earth's twin when Planetary Radio continues. Hi, Emily Lakdawalla here. Thank you for listening to Planetary Radio. The Planetary Society has lots more ways for you to hear the latest news and see the greatest pictures from around our solar system. I lead a growing family of expert bloggers at planetary.org. We cover nearly every angle on space exploration,

and you can find us all over online, tweeting, and posting to our popular Facebook and Google Plus pages. We're also producing great new videos for our YouTube channel. There's no doubt about it, we really are your place in space. Random Space Fact! Nothing new about that for you, Planetary Radio fans, right? Wrong! Random Space Fact is now a video series, too. And it's brilliant, isn't it, Matt? I hate to say it, folks, but it really is. And hilarious. See? Matt would never lie to you, would he? I really wouldn't. A new Random Space Fact video is released each Friday at youtube.com slash planetary society. You can subscribe to join our growing community and you'll never

miss a fact. Can I go back to my radio now? Welcome back to Planetary Radio. I'm Matt Kaplan, continuing my recent conversation with astrophysicist and planetary scientist Sarah Seeger. Sarah is working to create the instruments and techniques that will finally enable us to discover what is almost certainly waiting for us out there in the Milky Way, another planet like our own warm, wet Earth. One of the projects is TESS, the Transiting Exoplanet Survey Satellite.

You described this new spacecraft to be launched in 2017, TESS, as sort of a, tell me if I'm describing this properly, sort of a finder scope for the JWST. Yes, it's a finder scope for the James Webb Space Telescope. And in fact, it's likely the reason that test was selected to go forward, not just in and of its own self-finding out a lot about planets, but to provide a pool of planets that the James Webb Space Telescope can observe. You, in particular, study atmospheres, which, thank goodness, we're now at the level where you're beginning to get data, where you actually can begin to analyze the atmospheres of exoplanets. We have a long ways to go, though, don't we?

Well, yes and no. I'd say that when we started, we had an even longer way to go, where we had no exoplanet atmospheres available. And we were constantly told to not bother do what we do, because when are we ever going to observe any? Now we have so many, I don't even know how many we have. We have dozens of exoplanet atmospheres we've measured very crudely, admittedly. But we have about five that we've measured in enough detail to actually get a handle on what's going on in those atmospheres. Can you characterize the kinds of planets that we have atmospheric data for so far? What we can do with exoplanet atmospheres now, and these are hot, giant planet atmospheres typically, is we can look for molecules. We can see if there's clouds there or not.

And in some cases, we can measure properties of its atmospheric circulation. Ultimately, or maybe not ultimately, but with the JWST, what else do you hope you'll be able to do? Do you look forward to being able to look at Earth-sized planets and say, whoa, there's water or oxygen? Yes. I mean, our main goal is to characterize the atmospheres of rocky planets in the habitable zone of the host stars. It's still going to be tough. I mean, to think of it this way, think about the Hubble Deep Field or the Hubble Ultra Deep Field.

It's like doing a deep field on every transiting rocky planet. It could be 100 hours or more of observations to try to see what's there. So it by no means won't be easy. And that's why in exoplanets we're also looking forward to the study of giant planets. All the questions we have now from observing exoplanet atmospheres with the Hubble Space Telescope and the Spitzer Space Telescope and on the ground, we're going to blow all of that data away in the blink of an eye with the James Webb Space Telescope. So it's going to be literally a revolution for exoplanet atmospheres.

What do you want to find? I mean, what are the signatures, the spectroscopic signatures that you most hope to see that would tell us, hey, there may be something biological going on there? Well, to start with, we'd like to see water vapor on a rocky planet where water vapor shouldn't exist. We'd like to see water vapor because it may speak to the reality of liquid water oceans being on that planet. We'd like to see maybe some carbon dioxide to know that it's a terrestrial planet. The whole field of what to look for in terms of signs of life, it is all over the place right now. I think we're coming to a convergence.

And we have our favorite things we want to see, but we're still uncertain as to which one, if we could choose. We don't have a choice, but if we could choose which is our most robust gas to look at, we always fall back on oxygen. But trust me, we have a list of many, many, many, many, many more other things. Are we still talking, even with the JWST, about not being able to directly image these planets? Yes. The James Webb Space Telescope was not designed to directly image planets. It doesn't have the proper coronagraph, or there's no starshade that will fly in formation with the James Webb Space Telescope. So right now, in terms of small or solar system-aged planets, the James Webb Space Telescope is limited to transiting planets.

So what are we going to need up there? What sort of instruments are you looking forward to that are going to take that maybe biggest of leaps and let us actually view these things directly and maybe even see some details on the surface? Well, believe it or not, the community has been working in earnest on direct imaging from space for about 15 years, actually even longer. But what we want to do is to be able to block out the starlight

so we can see a planet like Earth in reflected light. And that's a huge challenge. My personal favorite concept is the star shade. The star shade would be a giant screen in space about 30 meters in diameter. It has to be very specially shaped to block out the light from the star so that only planet light enters the telescope. The star shade would have to fly information, something like tens of thousands of kilometers from the telescope. And the star shade, it sounds like a crazy idea, but really, manufacturing that star shade, we measure it in microns and millimeters, and the distances for formation flying are in hundreds of kilometers precision or within a meter laterally. So they're all big, actually big numbers we can work with. We're not

talking about picometers or some very, very even more challenging number to work with. I was just talking, in fact, with one of the engineers here who is working on the star-shaped concept, and they've done some testing in the desert with scale models, and he seems to be pretty confident that these are engineering challenges. Well, yes, because the concept of the star shade is really a mathematical concept. It's about diffraction of starlight. And that math has existed for a very long time. And so the star shade and other laboratory tests

actually just demonstrate that the math works like we expect. And so the folks here working on the star shade and elsewhere, yes, we're definitely confident that the math works out. It's the one thing we're confident about. You're working on other things that are going to go up in the space, at least I think you are. And one in particular I'm very interested in because we're the Planetary Society. We have a CubeSat 2, our light sail spacecraft. Are you still working on a CubeSat? Yes, actually. Back to transiting planets, the story begins about a

decade ago when the original concept for direct imaging in space called Terrestrial Planet Finder was a big NASA mission. At the cost of $50 million per year, it got shelved. And after that happened, I thought, wow, this is bad. What could we do to find an Earth? What if there's an Earth around a very nearby star? And what if that Earth is transiting? We have no way to find it. Kepler looked at hundreds of thousands of stars, but they're all very far away.

So I came up with the concept of what we called exoplanet sat, a three-unit cube sat with a small telescope inside. And the goal would be to send up a lot of those. Each one would look at its own bright sun-like star. The point is that if there's a transiting Earth around a bright sun-like star, we want to know it's there. But if there's not one, that's okay. But we don't want to miss our chance at finding one of those.

So exoplanet sat was a microcosm of any other space telescope mission in that it was more expensive than we expected. And we had management issues. We had everything. But what's going on right now is that now its home is at JPL. And two of my excellent PhD students graduated from MIT. They focused on ExoplanetSat during their PhD. They're now employed at JPL. So the team is now centered at JPL, and we're building a prototype that will launch probably in, I'll say, mid-2016.

Our goal is to propose for a NASA Explorer-class mission of opportunity, and we've costed out how we can get 10 of them launched for our Phase 2 of the program. Do you feel like the discovery of Earth 2.0 is almost within our reach? Yes, the discovery of Earth 2.0 is within our reach. However, nature has to deliver. Nature has to have to mate it so that Earths are common for us to be able to find them with the telescopes we can foresee in space in the next two decades. If it's not me who finds Earth 2.0, who's it going to be? And so I have my trainees. I find the most promising young people I have, and I work hard on them, not just on their technological skills but on their leadership ability

and their ability to organize and to make things happen because it may be that what we really require is a 10- to 20-meter telescope in space, and that will be the next generation that builds and leads that effort. Sarah, I thank you for that work, training the astronomers and exoplanet hunters of tomorrow. But I sure hope that you and I are around to celebrate when that second Earth is found. We're doing whatever we can to make it happen.

Thanks so much for being on Planetary Radio. Thanks, Matt. Planetary scientist and astrophysicist Sarah Seeger. I want to thank Northrop Grumman for helping to get us together. The company's aerospace systems division is where much of the James Webb Space Telescope is currently taking shape. Time for What's Up on Planetary Radio, which means that Bruce Betts is at the other end of the sky flying. He's the director of science and technology for the Planetary Society.

Welcome back and happy holidays. Happy holidays to you as well. Thank you. What kind of holiday skies do we have? We've got a holiday resurgence of planets in the sky. We've been partying with Mars and Jupiter for a while, but now Venus and Saturn are playing with us again, or at least trying to. So we've got very low, still a little challenging to see, but low shortly after sunset, low in the west. You might be able to pick up Venus, and it's going to come up and be wonderfully awesome for many months if you miss it now. Mars up in the early evening in the southwest

looking a lot dimmer and reddish, but still cool. And Jupiter coming up around 9 or 10 p.m. looking super bright over in the east. And in the pre-dawn, Saturn. You can see it hanging out near the moon on wednesday and thursday december 19th and 20th in the pre-dawn east planets for the holidays on to this week in space history it was 1968 that apollo 8 was launched sending humans around the moon for the first time 1988 two cosmonauts returned to Earth after spending a year in space on board Mir. And 2012, Grail A and B spacecraft, as planned, impacted the moon after their gravity mapping mission.

And I'm old, so I can actually remember the Apollo 8 astronauts giving us their Christmas greetings as they showed us the Earth as human eyes, naked human eyes, had never seen it before. Cool. No, it was seen it before. Cool. No, it was a spiffy mission. Sorry, I don't quite remember it. Yeah, you're too young. But I picked up later, Apollos. On to...

Realm of Spires! That had a lot of holiday spirit. It did. Speaking of the Moon and Mars, which I don't know if we were, even at its closest, Mars is over 140 times farther from the Earth than the moon is. Over 140 times. So to state it a different way, if we had a scale model where the moon's a football field away, then Mars would be over 14 kilometers away, about 9 miles.

That sounds remarkably like material for a random space fact video. Mmm, indeed, indeed. On to the trivia contest. We asked you, what bright star in our sky is Pioneer 10 approximately headed towards and will reach the vicinity of in a mere two million years. How do we do, Matt? All right. Well, first, I have to mention Mark Smith, who wrote in to say he had the right answer.

Aldebaran? Am I saying that correctly? As far as I know. But he said your actual language when you asked this question two weeks ago was what relatively bright star? language when you asked this question two weeks ago was what relatively bright star and you've corrected yourself because he says i would hardly call the 14th brightest star in the night sky relatively bright i think it would at least qualify as bright which mark smith certainly is is as well okay i i thought that would be worth uh mentioning As is mentioning that our big winner this time around is Alan Liddell. Alan Liddell of Mishawaka, Indiana, who indeed said it's Aldebaran, right? In two million years? It is indeed. Set your calendar.

So congratulations, Alan. He adds he thought that they blew up Aldebaran with the Death Star, but I think, no, that was Alderaan, right? Yeah, that was Alderaan. Very different. Yeah. Not too far. It's probably in the same stellar neighborhood. Not so much. Not so much. Alan, you're going to get the Year in Space wall calendar and the Year in Space desk calendar, and those are terrific. I use them all the time, and I happen to know that Bruce relies on them as well. I do indeed.

This week in space history. This week came from the Desk Calendar version. A couple more I want to mention. Sarah Lubert, she provided this number for the distance to Aldebaran, 68 light years, but also not quite 352 quadrillion fathoms. Ah, fathom fan. Okay, what have you got for next time? There is a U.S. penny on the Curiosity rover.

What year is it? What year is the penny on the Curiosity rover? Go to planetary.org slash radio contest. I didn't even know that there was a coin up there. You've got until the 23rd, that's December 23rd, at 8 a.m. Pacific time to get us this answer, and we will once again provide the winner with a nice desk set. Well, desk and wall set, the desk and wall versions of the year in space calendar. Excellent. All right, everybody, go out there, look up in the night sky and think about your favorite kind of tennis shoe and what color

would it be if you could design it yourself? Thank you and good night. I'd go for basic black, I suppose. He's Bruce Betts, the director of science and technology for the Planetary Society, joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California and is made possible by the Earthling members of the Society. Clear skies.