Planetary Radio: Space Exploration, Astronomy and Science - Tasting a Super-Earth's Atmosphere

Episode Date: January 31, 2011

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Music Getting a taste of a super-Earth's air, this week on Planetary Radio. Music Welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. Astronomer Jacob Bean leads a team that has begun the very first atmospheric analysis of an extrasolar planet that is not much bigger than our own. We'll talk to him about this ongoing work.

You'll never guess what's in store on today's edition of What's Up with Bruce Betts. No, really, you wouldn't guess it in a million years. And Bill Nye is just a couple of minutes away. He'll commemorate the loss of American astronauts in the three missions whose anniversaries are all remembered in this week, including the just-past 25th anniversary of the Challenger disaster. Normally, we'd be turning to Emily Lakdawalla right about now. Unfortunately, she is a bit under the weather and asked for a break.

So a quick review of the Planetary Society blog falls to yours truly. Emily does want you to know that the February edition of her own What's Up? is almost ready to post at planetary.org slash blog. Watch for this always excellent review of current missions around our solar system. It is sure to include Stardust, which is nearing its February 15 encounter with Comet Tempel 1.

The spacecraft has just sighted its objective. You can see the images in one of Emily's January 26 blog entries. We'll link to it from the show page. Also on the 26th, a self-portrait taken by Icarus, the experimental Japanese solar sail that is at the end of its life. You may also want to read a unique remembrance of the Challenger disaster by a scientist. He tells Emily he was at the Jet Propulsion Lab on January 28, 1986. He had been watching the images of Uranus being returned by Voyager 2 when he switched a tiny TV monitor over to the space shuttle launch. It's quite a story. We'll link to this blog entry as well.

One additional note, have you seen Bill and Matt's excellent adventure? I accompanied Bill Nye on a tour of SOFIA, the 747, that has a 100-inch infrared telescope mounted in its fuselage. I think you'll enjoy our no-budget video about this fascinating trip. You'll find it in the Features column at planetary.org. And speaking of Bill... Hey, hey, Bill Nye the Planetary Guy here. This week is the triple anniversary of Apollo 1, which was a spacecraft which never flew, but they had a fire

on board killing three U.S. astronauts. The Challenger space shuttle, which blew up shortly after takeoff because of the famous or infamous leaking O-ring. And the Columbia space shuttle, which burned up trying to re-enter the Earth's atmosphere. So these are three space accidents in which human lives were lost. Serious, serious business. But I remind us all that these people were very serious explorers. They were astronauts willing to risk their lives to find out what's out there. It's an exciting thing, really. Now, the stuff that went wrong with each of these accidents was not, if I may, rocket science.

Too much oxygen soaked into the foam rubber or the plastic foam in Apollo 1, and once the fire got started, it was not going to stop. On the Challenger, it was too cold. You couldn't tell whether or not the O-ring had seated properly with this kooky test procedure they have. And then the Columbia punched a hole in its space shuttle tiles and its re-entry tiles. And people thought about how that could happen. Oh, that could happen. But it really did happen. And it killed people. And then once again, when things go wrong in space or things go wrong anywhere, it's usually not just one cause. It's a multiple thing and multiple number of things hooked together that lead to trouble.

But nevertheless, it's worth a moment this week to take a little time and think about how these people really knew what they were doing, and they believed in it. They believed in pushing the boundaries for the betterment of humankind so that we could reach farther out there, deeper into space. And you know what they were hoping to find? Nobody knows. That's why they were going. So take a moment this week and honor the astronauts who gave their lives in the exploration of space. And let's push out farther and deeper into space and take more risks. But let's be careful with human lives. Well,

thanks for listening. I've got to fly. Bill Nye the Planetary Guy. I goofed last week. I said we'd next be talking about the first analysis of an extrasolar planet atmosphere. I realized soon after that I should have said the first analysis of a so-called super-Earth's atmosphere. That recently published study was led by Jacob Bean, a NASA Sagan Fellow and astronomer at the Harvard-Smithsonian Center for Astrophysics in Massachusetts. Sagan Fellowships are awarded to outstanding postdoctoral researchers who tend to be among the youngest in the field.

Jacob is certainly off to an auspicious start with this work. Imagine attempting to taste the air of a world that is far too many light years away to actually see, at least with current technology. But that technology is advancing far faster than anyone could have predicted just a few years ago. Jacob Bean recently spoke to me from his Harvard office. Jacob, thanks very much for joining us on Planetary Radio. It's my pleasure to be here. What can you tell us about this world that we know as GJ 1214b?

GJ 1214b is a very interesting planet because it's what we call a super-Earth-type planet. Now, a super-Earth-type planet is a sort of fascinating kind of object because it's defined as something having a mass a little bit more than the Earth, up to about 10 times the mass of the Earth. Now, what we think is this is a transition region between mostly terrestrial-type planets up to icy and gaseous giant-type planets like Uranus and Neptune in our own solar system. Now, the theory that we have doesn't really guide us on what to expect in this region other than we have this transition. Maybe we have overlap of high-mass, gaseous, and icy bodies going down in this low-mass regime, or we have large super-Earth, true super-Earth,

large terrestrial-type bodies moving into higher mass regime. And so what we want to do is we want to look for these kind of planets and measure their properties and try to understand their basic composition to understand how frequent are terrestrial planets or how frequent are these large, giant, icy planets. TEL-14b sits in the transition region, and it's the second transiting super-Earth that has been detected. And when a planet transits, that means it passes in front of its host star, and we see a little dimming in the light coming from the star. We're able to measure not only its mass, but its radius,

and this is an important constraint on the structure of a planet. There's a problem with these super-Earth planets with only knowing the mass and the radius. We can't actually determine exclusive, we can't identify an exclusive composition for the planet. And the problem is that it's probably got an atmosphere over the top of it, and this planet almost certainly has an atmosphere. And so that means we have to be able to probe and analyze the composition of the atmosphere to understand the basic composition of the planet itself. And so that's what we've done.

We've made the first measurements of the atmosphere of this planet, GJ 1214 b. And so the important thing is we get a constraint on the atmospheric composition, and this leads to a further constraint on the basic overall, so to say, bulk composition of the planet. So what can you tell us about the atmosphere of this world, which, you know, it's not the first to have its atmosphere analyzed, but it is the first of these super-Earths, as I understand. That's right. This is the first super-Earth, an atmosphere has been analyzed. And our observations

primarily probe the sort of, say, puffiness of the atmosphere. We're mostly sensitive to the hydrogen content in the atmosphere. And what we were trying to determine was really how much hydrogen this atmosphere had in it. If it had a large amount of hydrogen, this would suggest the planet was more akin to the ice giants in our solar system, like Uranus and Neptune. If it didn't have a large amount of hydrogen, an alternative possibility was a large amount of water vapor, sort of like steam. And this would suggest a very different kind of

planet, a planet very water-rich, not water in the sense that oceans and lakes. We're talking about a high-temperature water vapor and transitioning down to high-pressure, high-temperature sort of, say, ice. But this is nothing like we'd ever seen in our solar system or even outside our solar system. And so our measurements actually reveal that the atmosphere probably doesn't have a lot of hydrogen. The atmosphere is not very puffy. So this suggests the atmosphere could be predominantly water vapor. Now, there was a complication in that our measurements are not giving us a definitive answer. There's also the possibility that there are clouds or hazes

at high altitudes in the planet's atmosphere that are sort of blocking our view to lower layers. So this is where we stand now. We've made these first measurements, and they haven't given a definitive result. But it's very exciting that we're actually able to do this for these kinds of very small planets. And I have a hope that over the next year or so, we can get some further measurements to distinguish between these two possibilities. What would it mean if we found that this planet has a lot of water, a lot of clouds, basically, in its atmosphere? I'm sure that's wrapped up in its relationship with its star, which,

again, as I understand, is a pretty feeble little light. its star, which, again, as I understand, is a pretty feeble little light. That's right. The star is feeble. I don't know. It's sort of a weak term. I mean, the star is a very small star. Its mass is about 16% the mass of the sun, and its size is about 20% the size of the sun.

But these stars are actually sort of the heavyweights in terms of numbers in our galaxy. They actually make up about 75% of stars like this, make up 75% of all the stars in the galaxy. So individually they're quite small, but as a population they're quite significant. Now these stars are also quite interesting because this small size makes these small planets easier to find and study. So from a practical standpoint, these stars are actually really good. This is because the planet is relatively large compared to its star? That's right. The measurements we're making are, in their essence, we're measuring the size of the planet relative to the size of the star. So for a given level of measurement precision that we can obtain with our technical capabilities, if you just look at smaller stars, you can look at smaller planets.

So that's actually a good thing. So these stars might be feeble in terms of their individual properties, but as a population and as a laboratory for studying extrasolar planets, they're actually quite interesting. So back to your other part of your question, what does this mean in terms of if we found a planet that was water-rich? Well, like I said, that would suggest this planet was fundamentally different than anything that we have in our solar system. This would indicate probably a wider diversity of planets in the galaxy than we had really previously expected. And the question would be, how common are these objects?

The fact that we found one so soon suggests they could be quite common, but that's something we'd like to answer with further work. That's Sagan Fellow and Harvard-Smithsonian astronomer Jacob Bean. He'll tell us more about his study of planets circling other stars, including their atmospheres, when we return. 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.

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analyzing the atmospheres of extrasolar planets. This incredible work has been underway for several years now, beginning with giants circling close to other stars, but steadily progressing to worlds like our own. Astronomer Jacob Bean is telling us about GJ 1214 b, a planet that is not even three times as big as Earth, that orbits a small, dim, unremarkable star about 40 light-years from our home. It is increasingly clear that there are countless other worlds like GJ 1214 b,

and very likely countless worlds even more like ours. It sure looks like, I mean, from the other folks that we have talked to on a regular basis about the discovery of exoplanets, that this continuum of the diversity of planets really is headed toward, I don't know about the infinite, but it really is a pretty rich family of worlds. Yeah, I think that's true.

There's going to be a continuum that these objects sit on. Astronomers, I think scientists and astronomers in particular, like to put things in boxes, discrete boxes. We like to say, this is a gas giant like Jupiter and Saturn, or this is an ice giant like Uranus and Neptune, or this is a terrestrial planet like Earth and Mars. But we're probably going to see this continuum, and that's not completely unexpected. When you were starting with only eight examples in our own solar system, now we're branching out to more than 500 extrasolar planets. I think we'll probably reveal this continuum.

But there are discrete boundaries, I think, where you have most objects are grouped into little bunches. But there's definitely going to be more of a continuum, I think, than our own solar system demonstrates, just because of the small number of planets, relatively speaking, that we see. I'll ask you to speculate for a second or two. Even though this planet is so close to its star, is it possible to imagine, if it's water-rich, that it occupies a habitable zone? Yeah, definitely not. This planet is a bit too warm. It has a temperature roughly around 550 degrees Kelvin, which is a bit too hot.

Toasty, yeah. Yeah, it's a bit too hot. But this is the coldest planet, the coolest planet, I like to say. There's a double meaning there. This is the coolest planet that we've been able to do this kind of study on. And so over the last, sort of say, 10 years that we've been doing atmospheric studies on extrasolar planets, we've gone from Jupiter-type planets to Neptune-type planets, and now we're in this super-Earth regime. And I don't think anybody would have thought we would have been able to do this so quickly.

So we're just knocking on the door, I think, of doing an atmospheric study of a planet that is potentially habitable. I think that will definitely happen in the next five to ten years. Wow. Well, let's hope so. Talk about the instruments that enabled you to do this work. Well, there's actually kind of a history to this. First, the planet has to be found, and that's no mean feat. And it was found actually with a rather sort of, say, clever way of doing things. I've mentioned this planet transits its star.

That means it passes in front of its star, you know, once during every orbit. And so you see a dimming in the light from the star. So this planet was found actually via that method, where you're looking at a large number of stars, and you're waiting to see that dip. And every time you see a dip, you have to go look at it very carefully, make sure it's the right kind of dip, and that sort of thing. But this was actually found with a ray, so eight small amateur class telescopes, as a project led by a professor here at Harvard, David Charbonneau. So this was found with off-the-shelf amateur quality

equipment. Now, he had eight telescopes, whereas the usual amateur would only have one. But really, this is not some fancy technology. Now, just to find the planet, he used that method. So that would actually give you the radius of the planet, which is very interesting. But we also want to know the mass of the planet. And to do that, radio velocity measurements have been used. And this means that you're watching the acceleration of the star along a line of sight. You see the absorption lines in the star's spectrum shift due to the Doppler shift. To make those measurements, that's a very precise measurement.

That required a very sophisticated instrument on a 3.5-meter telescope in Chile called the HARPS instrument that can measure these Doppler shifts very precisely. Once that was done, we had the mass and the radius of the planet. We could see that it probably had a significant atmosphere due to its large size for its mass. And then the question was, what was its atmosphere? So to do our study of the atmosphere, we went to an even larger telescope now. We used the VLP telescope. It's almost a very large telescope.

It's a facility of four 8-meter telescopes in Chile. And we used one of these 8-meter telescopes to observe two of these transits. You know, we observed twice as the planet passed in front of its star, and we watched as the light filtered through the planet's atmosphere. And doing a very careful correction to this, we were able to reveal what the planet's spectrum actually was. So there's a wide, like, variety of facilities and instruments that have been used, and then all this comes together to lead us to this insight about the characteristics of this planet.

Do you feel fortunate to be part of this first generation of astronomers that has access to these exquisite instruments? Oh, absolutely. I think it's a very fun time to be working on exoplanets. I'm not sure I'm part of the first generation. That would be, I think, the people that are a little bit older than me, they were able to work on this in sort of, say, the early 2000s and late 1990s. But certainly I feel very fortunate and it's very exciting to work on this. And you're a young guy.

You've got hopefully a very long and continued successful career ahead of you. What are you up to next? Well, the next thing for me immediately will be to make some further observations of this planet to try to understand more in detail really what it's made out of. Over the next five to ten years, I'd like to continue study of planets orbiting these very small stars so that we can continue to push towards finding and characterizing smaller and smaller planets, and ultimately a potentially habitable planet where we can actually look into its atmosphere and try to look for biosignatures in the planet's atmosphere.

Jacob, congratulations once again. Again, thank you very much for joining us today on Planetary Radio. All right, it's been my pleasure. Jacob Bean is a postdoctoral researcher with a Carl Sagan Fellowship at the Harvard-Smithsonian Center for Astrophysics. That's at Harvard University in Massachusetts. We'll be right back with another astronomer. Bruce Betts will make his weekly visit, tell us what's up in the night sky, and much more in just a few moments.

Bruce Betts is on the Skype line. He is the director of projects for the Planetary Society. He comes in every week, every week without fail, to tell us about the night sky. And we've got some other very cool stuff today. I'll just give this clue. Harmony. And it's not part of the International Space Station. Just stay tuned.

I'm teasing here. Is it a sign of how beautifully we get along? It could be, but not in this case. No, probably not. Tell us. How's the night sky? It's hunky-dory swell, Matt. It's got Jupiter still up. It's starting to get lower in the west in the early evening, but still a bright star-like object dominating the west. February 6th, you can check it out. Beautiful, beautiful sight next to the crescent moon.

is dominating over in the east, looking bright star-like object-ish. And you've got Saturn actually rising before midnight now in the east and high, high in the sky in the pre-dawn, looking groovy and spiffy. You can check out the constellation Orion in the mid-evening over in the southeast, looking bright with its Orion's belt and all those bright stars it's got. Let us go on to this week in space history. A lot of significant stuff happened this week in space history. In 1958, Explorer 1, the U.S. spacecraft orbiter, was launched. Three years later, we had the first hominid in space, which was, of course, Ham.

Ham launched 50 years ago this week. We love ham. I do love ham. Green eggs and ham but ham the chip as well is a hero for the age. You know I hear that was the food they provided with them on the flight. Green eggs. I wouldn't have recommended that but okay if it worked. So at Apollo 14 launching and landing on the moon and more importantly in 1971 Alan Shepard hitting the first golf shot on the moon which I know is near and dear to your heart. I can't remember if he yelled four or not. Well I don't think so because he actually hit someone

which seems so unlikely. One other guy on the entire body, and he beaned him. No, not true. No, it wasn't Alan Bean either. Ah. All right. And you've got something spectacular this week to introduce it rather than my feeble voice. Is that correct? We have something utterly amazing this week for you. It comes to us from Tom Moore, who apparently is a charter member, original member of the Planetary Society, but also the member of a barbershop quartet called The Edge. I get this email from Tom, and he has attached a file to it from his award-winning quartet in which he is the tenor. What can I say? It's amazing. Listen to this. Random space facts. Space facts.

Space That was incredible. I am blown away. I am just blown away. Tom and all of you guys in the Edge, thank you so much. We're going to try and do some more stuff with you on the radio show because we definitely need, everybody needs a quartet on their space radio show. That was really cool. I guess I should actually give one of those random space facts.

Yes, overwhelmed though you might be, please do. I am overwhelmed. Speaking of overwhelming, I thought I'd update you on the tracking and finding of near-Earth objects. That's near-Earth asteroids and comets. There are now more than 7,700 known near-Earth objects. Yes, the shooting gallery is getting crowded. Okay, it's still not crowded.

It's still a bunch of empty space, but there's a lot more objects that we're discovering out there. They were there before. We just couldn't see them. And near-Earth objects being defined as any small body passing within 1.3 astronomical units of the sun, where an astronomical unit is, of course, the average distance from the Earth to the sun, or about 150 million kilometers, or 93 million miles. 20% of this 7,700 population are classed as potentially hazardous objects, ones that pass within 0.05 AU of Earth's

orbit, or about 20 times the distance to the moon. So the ones we really have to pay attention to. That's more than, what, 1,500 or so of these guys that we got to keep an eye on. Indeed, and still hunting for more, especially the smaller ones. I strain my eyes nearly every night staring at the sky. Thank you so much. I have yet to find one, but keep staring, staring, always staring. We move on to the trivia contest, and we asked you about Jupiter. How many times more massive, so the mass, is Jupiter than the Earth?

How'd we do, Matt? Lots and lots of entries. I think there were many, many more people who wanted that second copy of Mike Brown's book, How I Killed Pluto and Why It Had It Coming. But the book, a Mike to Michael, because Michael Murphy in Dublin, Ireland, is our winner this week, and he's going to get that book. He told us that Jupiter is about 318 times the mass of Earth. So congratulations, Mr. Murphy over there in Dublin. We did hear from quite a few people, among them

David Kaplan and Camille Stefaniak, Ron Bask, that Jupiter is not just a whole lot bigger than Earth. It's two and a half times the mass of all the planets and other junk in the solar system combined, except for the sun. Indeed, a fabulous random space fact. It's big, you know, no matter how you cut it. Jupiter, big. You know, unless you cut it by comparing it to the sun. Can I give you one more of these? Oh, please do.

Our always humorous friend Torsten Zimmer, who said, had the total mass right, 1.9 times 10 to the 27th kilograms. But he's figuring that somebody is probably already converted that to its weight in monoliths. Anyway, I thought that was pretty cute. What do you got for next time? We're going to the galactic center. OK, we're not but we're figuring you tell me where in our sky the galactic center is specifically what constellation in which constellation is the galactic center located when we look up in the sky go to planetary.org slash radio just to be clear

when i refer to galactic center i mean our galaxy the milky way. Ooh, ooh, ooh, ooh. I know the answer, but I won't give it away. We'll wait. We'll wait until you get all your entries in by Monday, February 7 at 2 p.m. Pacific time. Do not, we repeat, do not go to the galactic center to figure this out because there's something really nasty going on there. Sorry, there's such an opportunity. Now I'm so, I mean, I know what you meant, but I'm picturing so many other things.

A bunch of angry gorillas. Smelly, smelly feet. It's all the alien tourist businesses that surround the black hole. It's that they just rip you off. It's where all the lost luggage and socks ends up, isn't it? That's right, of course. Every dryer on this planet has a direct line to the black hole at the center of the Milky Way.

Say goodnight, Bruce. It goes there at the speed of lint. Like that. E equals M lint squared. Obscure TV reference there. Good times. All right, we done? We're very done.

All right, everybody, go out there, look up at the night sky, and think about the smell of lint. Thank you, and good night. Remind me to tell you sometime about the simplified periodic table that my friends and I came up with. I think I have told you. And lint was one of the basic elements of the universe. But another time.

He's Bruce Betts, the Director of Projects for the Planetary Society. He joins us every week here for What's Up. Remember Planetary Radio Live? It's coming back, baby. We'll have more information for you in the coming weeks, including how you'll be able to attend the live recording session in Southern California. Who knows? Maybe a barbershop quartet will show up.

Planetary Radio is produced by the Planetary Society in Pasadena, California and made possible in part by a grant from the William T. and Eileen L. Norris Foundation. Clear skies. Редактор субтитров А.Семкин Корректор А.Егорова