Planetary Radio: Space Exploration, Astronomy and Science - Visiting the Earth-Like Worlds of TRAPPIST-1

Episode Date: April 11, 2018

We have begun to understand the composition of worlds that are hundreds of trillions of kilometers from Earth. Astronomer Nikole Lewis is co-leader of a team that has used the Hubble Space Telescope to do this with the four Earth-like planets circling a star called TRAPPIST-1. Host Mat Kaplan talks with Digital Editor Jason Davis about a new probe designed to discover thousands of additional exoplanets.  Want to win a Planetary Radio t-shirt? Answer this week’s space trivia question posed by Planetary Society Chief Scientist Bruce Betts. Learn more about this week’s topics and see images here: http://www.planetary.org/multimedia/planetary-radio/show/2018/0411-nikole-lewis-trappist-worlds.htmlLearn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

The Earth-like worlds of TRAPPIST-1, this week on Planetary Radio. Welcome, I'm Matt Kaplan of the Planetary Society, with more of the human adventure across our solar system and beyond. Nicole Lewis co-leads a team of astronomers and planetary scientists that has sniffed the air surrounding planets that are 40 light-years away. It's an astounding accomplishment, but there's even better to come, as she'll tell us today. It's a big week in space history, as you'll hear from Bruce Betts in our What's Up segment, among other things. Happy Global Astronomy Month!

GAM is well underway with events and activities available all over our planet. You can learn more when you visit astronomerswithoutborders.org. GAM is well underway with events and activities available all over our planet. You can learn more when you visit astronomerswithoutborders.org. Let's visit with the Planetary Society's digital editor, Jason Davis. He has written about the Transiting Exoplanet Survey Satellite. Jason, welcome back. Thank you for introducing us to TESS in your April 9th blog post at planetary.org. Share this with the radio audiences.

Is TESS going to out Kepler Kepler? Ah, yes. TESS. Welcome to TESS, our new exoplanet satellite. TESS will not out Kepler Kepler per se. It's going to do an all-sky survey. So whereas Kepler was kind of looking through a soda straw with a telescope almost, TESS is using these big wide-field cameras so that it's going to be able to actually, over time, over the course of two years actually, survey the entire sky. We say the entire sky,

it's actually like 90% of the sky. This will limit it a little bit because Kepler had this really high resolution and could see really distant exoplanets. But TESS, on the other hand, will be limited to brighter stars and closer stars. What this is going to do, hopefully, is find a lot more Earth-sized planets, find the smaller planets. So it's going to out Kepler on one degree, but at the end of the day, I guess they're kind of different missions. More like 360 degrees, I think. I'm looking at these slices that it will examine one at a time that do cover, you know, as you said, 90% of what may be out there to see, at least the bright stuff. And it's going to do it from a really kind of a wild orbit. Yeah, this is really cool. I guess it's an orbit that NASA has never tried before.

It's called technically a two-to-one resonance orbit. There's a technical name for it that I have since forgotten. But essentially, for every two orbits that TESS makes of Earth, the Moon makes one orbit. So it's like a roughly 13.7-day orbit. How long before it starts finding those new worlds for us. There'll be some initial commissioning orbits where it's raising its orbit to get into the final science orbit. I believe there are three commissioning orbits where it then ends with a lunar flyby that kicks it onto the final one. So between one and two months,

somewhere in there, before it finally actually starts doing the science and starts on this two-year mission. And as we speak, it's going to be headed into space on a Falcon 9 in, I guess the first opportunity is April 16? Yeah, so Monday is the target launch day, Monday evening, Eastern time here in the US. Of course, that's all depending on SpaceX doing the static fire for the rocket and

getting everything ready. But yeah, that'll be the first earliest attempt. All right. Thank you, Jason. A great update. There is much more. It is a lavishly illustrated blog post with some pretty cool videos as well. One that shows this odd, unique orbit the test will be taking up. And you can find it at planetary.org. As I said, it's an April 9 blog post from Jason Davis, my colleague, who is the digital editor for the Planetary Society. Thanks, Jason. Thanks, Matt. Much of our world's exoplanet research community has been focused on four worlds that are circling a star that is merely 40 light-years away.

Of course, merely is still about 380 trillion kilometers from our warm, wet, life-filled planet. But these worlds, known as Trappist-DEFNG, are becoming better known to us through the use of some of astronomy's most powerful tools, including the Hubble Space Telescope. It's the Hubble that has allowed one team to announce findings about the atmospheres of these worlds. Nicole Lewis is a co-leader of that team. She is an associate astronomer at the Space Telescope Science Institute in Baltimore, Maryland, and that's where she was when I spoke with her a few days ago. is an associate astronomer at the Space Telescope Science Institute in Baltimore, Maryland. And that's where she was when I spoke with her a few days ago. Nicole Lewis, welcome to Planetary Radio and congratulations on this work, now published a couple of months ago as we speak, that has told us even more about this pretty amazing system of planets that is 40 light years away from our own.

Very happy to have you on the show. Great to be here. Tell us about this system, the TRAPPIST-1 system. Your colleague Hannah Wakeford said that it's a goldmine for study of Earth-sized worlds. Do you agree? I do agree. I am trained as a planetary scientist, actually, and when this system was discovered, I was so ecstatic. It's an opportunity to do what we call comparative planetology. The planets are all roughly the size of Earth, and you have seven of them that formed around the same star. So you can do a lot of inner

comparisons. And the other great thing about this system is that it really provides an important link between our own solar system and then the Jovian moon system in our solar system, because really you have this small star with these Earth-sized planets around it. So this is really a goldmine for us to understand planets and planet formation. And this star that these planets revolve around, it's one of these red dwarf stars that are so common in our galaxy? Right. This is what we like to call a late-type M dwarf. So it's actually not that much bigger than Jupiter, and it's cooler, much, much cooler than our own sun. But these are the

most prolific type of stars in our galaxy. So they're everywhere. And most of the stars sort of in our solar neighborhood are these M dwarf, very cool stars. So you've started to touch on this, but mostly what we've heard about the TRAppist-1 worlds is how similar they may be to Earth or our own solar system, at least. How else does this system differ from ours? Right. So these planets are in very short period orbits. They have orbits that are much, much less than actually Mercury's orbit in our own solar system. So the innermost planet is basically going around in about a day. These planets, their years are on the order of a few days. They're probably tidally locked, which means they may have a permanent day and a permanent night sky,

just like the moon has a side that's always facing us here on Earth. The environment that they are existing in and the physical properties of the planets, such as their rotation rate, is very different than what we have here on Earth. Has this system always looked the way it does now with these worlds packed in so close to their star? Probably not. It's very, very difficult to form planets in situ next to each other in that formation. It's just not dynamically stable. More likely what happened is these planets formed, spread farther apart and further from the star, and then went through a process called migration, which we know has happened in our own solar system.

And they ended up coming in together and getting locked in these what we call orbital residences that allow them to maintain these stable, very, very closely packed orbit next to their star. Well, let's talk about this work that was published in the February 5th issue of Nature Astronomy. What has it told us? What other news has it brought us about at least some of these worlds? One of the great things about the TRAPPIST-1 system is that we have really no preconceived notion of what these planets and their planetary atmosphere should look like. We just can't take our solar system analogs and plunk them onto these planets around this M dwarf system. So there exists a very large phase space for us to explore. These planets could, in fact, still have what we call primordial atmospheres, atmospheres that are rich in hydrogen, which is

unlike what we have in our own solar system, where we've lost a lot of that hydrogen on our terrestrial worlds. So what we were doing with Hubble is we're doing these first probes into the planets to try and cut down that phase space. And so part of what we did was sort of rule out this primordial atmosphere scenario. And that allows us to better understand what atmospheric scenarios we should look for in the future. Are we sort of operating out at the limit of what Hubble is capable? It's pretty amazing to think that we could characterize or begin to characterize the atmosphere of anything that is so far away. No, I mean, Hubble has been a workhorse for exoplanet science, actually. And that's because we can get these extremely stable

and precise measurements. So even for these tiny Earth-sized worlds, in this particular system, we're able to probe the planets quite precisely. We've kind of reached the limit of what we want to do with Hubble, because to go beyond that would require a really substantial investment of time with Hubble, and that would exclude other science getting done. Instead, what we wanted to do is wait for the James Webb Space Telescope to come online to continue these probes of the TRAPPIST-1 planets. Along the same time we were doing these TRAPPIST-1 observations with Hubble, we were also doing what's the first treasury program on Hubble for exoplanet science. It's 500 orbits that's probing 20 different planets so that we can start to understand also gas giant atmospheres.

So there's a whole host of exciting exoplanet science that's being done right now with Hubble. And I'm so glad you brought up the JWST, which I learned you are the project scientist for at the Space Telescope Science Institute. I bet you can't wait to get your hands on data from that powerful new space telescope. Yeah, exactly. I mean, we're excited to probe a huge range of exoplanets with JWST because it's going to give us our first look into what we call infrared wavelengths. Basically, wavelengths that are longer than the visible wavelengths we see with our eyes, sort of what you might see with heat vision goggles, say. But infrared wavelengths are really important for studying planets. They help us to figure out what the temperature of planets are

and also to figure out what all these fun chemicals are in their atmospheres. So, you know, we're going to be looking at Jupiter-sized planets, but the TRAPPIST-1 system has really presented us our first opportunity to study these small rocky planets with JWST right from the get-go. So do you expect that when JWST comes online, and by the way, you must be at least a little disappointed to have seen that recent announcement that it's going to be delayed once again, are we going to have the power? Do we project that JWST may be able to tell us more. For example, is there a chance that it will be able to find elements like oxygen in the atmospheres of some of these worlds? Yeah, JWST is going to

be able to probe a broad range of these molecules, oxygen being one. Oxygen by itself does not tell us that life exists on a planet. In fact, Mars has oxygen in its atmosphere. What you really need to look for is a bunch of different chemical fingerprints, these different molecules, oxygen, carbon dioxide, methane, water, and see what the relative abundance of those are to tell us, is there something on that planet that's affecting the atmosphere and could that be life? And JWST actually provides us with the broad coverage in terms of wavelength ranges that will allow us to look at all of those chemical species. So we're going to be able to start putting these puzzle pieces together and start asking those hard questions of, is what we're seeing in these

planet atmospheres a signature of life? Or maybe it's some other process like volcanic, geologic, photochemistry. There's lots of different things that can create these chemical signatures in these planets' atmospheres. What would you be most excited to find in these atmospheres? I mean, I remember, and I think it was only half serious, the speculation that wouldn't it be fun if we found CFCs in the atmosphere of some world? And we'd know that not only is there intelligent life there, that they're probably no more intelligent than we are. Right, right. You know, CFCs are hard to find because they are, even though we've been pumping them into the atmosphere, there are very small trace species in our own atmosphere.

And even if someone was observing Earth from far away, it would be hard for them to see those tiny little trace species in the atmosphere. Earth from far away, it would be hard for them to see those tiny little trace species in the atmosphere. Instead, most of our focus has been looking at these bulk composition for the atmosphere, carbon dioxide, the ozone, these big molecules that provide us with very large signals. And at this point, I would be excited to see any of those molecules. And actually, more exciting for me is that I'd be able to measure exactly how much of those molecules, because we haven't really been able to do that to date with facilities like Hubble and Spitzer. Nicole Lewis of the Space Telescope Science Institute. She'll have more to tell us about the worlds of TRAPPIST-1 when we return. This is Planetary Radio.

Hi, I'm Bruce Betts of the Planetary Society, and I'm here at Honeybee Robotics in Pasadena, California with Justin. Hello. And Catherine. Hello. Who are engineers on the PlanetVac project. Grabbing dirt and rocks on another world is hard, but it enables profound discoveries about the solar system. What am I looking at? PlanetVac prototypes from quite some time ago all the way up to just a few days ago.

PlanetVac, a new reliable low-cost technique for collecting planetary surface samples. Help us take this technology through the next level of testing on a Zodiac rocket, thus enabling PlanetVac's use on missions to Mars and other worlds. Learn more by visiting us at planetary.org slash PlanetVac. That's PlanetVac! PlanetVac! Welcome back to Planetary Radio. I'm Matt Kaplan. Four of the planets circling a dim star called Trappist-1 are in that star's so-called habitable zone,

where water could exist as a liquid on its surface, just as it does here on Earth. And all four are pretty close to Earth's mass and radius. So it's no wonder that astronomers like Nicole Lewis are dedicating so much of their professional lives to studying them with every appropriate tool. So everybody knows Hubble, of course, but you've also done a lot of work with the Spitzer Space Telescope, another of those great space telescopes. Did it pave a path in the infrared astronomy that it did for JWST?

Absolutely. I mean, I honestly cut my teeth on Spitzer as a graduate student. And it's really taught us a lot of the important techniques that we're going to need to use with JWST. In particular, Spitzer has helped us to understand how to probe climate. So one of the big things I do is looking at weather on exoplanets, and you can only do that with an infrared space telescope. All of those techniques and a lot of training has been done with Spitzer. And we've also done a lot of free observations of systems. So we already know exactly how bright those systems are at those important infrared wavelengths, which help us to better plan our JWST observations. As I've said before on this show, I'm old enough that I can remember my, you know, elementary school textbooks telling us, first of all, we'll never see a star as more than

a point of light, and we'll certainly never be able to detect planets around other stars. And now here we are learning or beginning to learn about what's in their atmospheres and their weather, their climate. Yes. Yeah. No, I mean, it's been a very transformative, you know, basically decade. We are entering what I like to call the era of characterization. A lot of the first exoplanet science was really focused on detection, right, which is great. But now we're getting to the point where we're using facilities like Hubble and Spitzer that were never designed to look at the atmospheres of exoplanets, and we're finding clever ways to use them to get that information out. And we're doing it quite well and reaching very, what we call, high-precision observations.

And of course, this work is underway all over the world. On the very same day that your team's research was published, we learned even more about the seven TRAPPIST-1 planets. Are you familiar with this work by researchers at the University of Bern that was led by Simon Grimm? Yes, yeah. So this is work that was follow-up of the original observations done with Spitzer that detected the presence of these seven planets in the TRAPPIST-1 system. And the great thing about the TRAPPIST-1 system is that they are in these tight packed orbits and in these orbital resonances, which give us an opportunity to look for variations in what we call the time that they pass in front of their host stars or their

transits. And using this information, we can actually measure their masses. So because the system is in these tight packed configuration, it's giving us an opportunity to directly measure the masses and the radiuses of these planets. This is something that Kepler has also done with these tightly packed systems. And once you know the mass and radius of a planet, you can tell what its bulk density is. So then you can start to think about, well, what is this thing made of? And for the TRAPPIST-1 system, we're seeing that these planets are what we call volatile rich.

So they have a substantial fraction of water probably in these planets as well. Again, this provides a nice link between our own solar system and, of course, the Jovian and Saturnian moon systems that we have here. I was shocked to see that these findings by the team at the University of Bern said, yeah, there could be up to 5% water on some of these worlds, which didn't sound like much until I read that Earth is only 0.02% water. So 5%, my gosh, that's a lot of water. That's a lot of water. But this is, again, a lot more similar to what we see in some of the icy satellites in our outer solar system, right, that are very water rich. And again, we're around a small type star that's providing us this link between our own sun and Jupiter and how maybe Jupiter formed its moon. So from that standpoint, these planets are probably

somewhere in between being Earth-like and being, say, Europa-like. We can't really say yet, can we? I mean, of course, some of them are in that Goldilocks habitable zone where they should have liquid water, this high percentage of what may be water. Can we say with any confidence that there is or should be liquid water there? We can't say, because again, to talk about habitability, usually people want to know about the presence of liquid water on the surface of the planet. And the surface amount of water is controlled a lot by the atmosphere. And so at this point, we know that the atmosphere is not primordial, it's not hydrogen rich, but there still remain a lot of different scenarios that could exist there, including only a very tenuous atmosphere.

there, including only a very tenuous atmosphere. It could be that the water is all locked up into the mantle of the planet, or it's possible that some of that water is actually on the surface and that there's an atmosphere that's able to maintain that stably. So are you excited about the prospects for the Europa Clipper mission that is going to tell us so much more about that moon of Jupiter? Yeah, definitely. As a planetary scientist, a lot of what I do is take what we've learned by being able to go in situ, being able to send probes to planets and moons in our own solar system,

which we still have a lot to learn about, and taking that and applying it to exoplanets where we don't really have any near-term prospects for sending a probe to those planets. So we have to do a lot of, this is what we've learned from the solar system and applying that to exoplanet systems where we don't have an opportunity to say, send the Europa Clipper. Back to this understanding that we've gained in only the last 20 years or so, beginning with the fact that there are worlds throughout our galaxy, that the star that doesn't

have planets is the exception. Do you expect that we will find not just many planets, many worlds, but worlds that are as similar to Earth as we seem to be discovering at TRAPPIST-1 throughout the galaxy? Yeah, I think we're going to find that there's a lot more diversity than we expected. I think one of the big things that we've learned in exoplanet science is to expect the unexpected. The first exoplanets that were discovered were these hot Jupiters, these big Jupiter-sized planets that are in these day-long orbits. So they're parked right next to their host star. And for a long time, people have believed that was impossible because it didn't make sense in the context of our solar system. So as we approach these other systems, it's important that we have to understand that there's a broad range of possibilities. And we may find some that

look very similar to Earth, but we may find others that don't look like Earth, but could also still potentially support life. So I try to approach this sort of with an open mind. And that's what we do in our observations, as we don't have a preconceived notion as to what the Trappist-1 atmospheres look like. Instead, we just do a full exploration of the parameter space. characterizing these other worlds. But it's painstaking work. I mean, working with this transit data and the other meager data points that we're still able to get in the absence of better instruments. What kind of led you in this direction? And do you find it satisfying? I do find it satisfying, but I really, I like to, I'm a problem solver and I'm willing to, you know, stick with things literally for years. My first paper with Spitzer took me almost three years of analysis in order to probe the weather of this planet called HAT-P2B.

And so people who get into this field have to be folks who are willing to be dedicated and really dig deep into these data to find very, very small signals. But there are lots of people who are just very excited about exploration, right? People are driven by exploration and finding more information in the data that we have and then thinking about maybe the best ways that we can get even more details with future observations. It is heroic work, Nicole. Thank you for doing it.

And thank you to your entire team that is revealing so much more exciting information about worlds like these seven worlds in the TRAPPIST-1 system and keep it up. Excited to do it. Nicole Lewis, she is an associate astronomer and the James Webb Space Telescope Project Scientist at the Space Telescope Science Institute in Baltimore, Maryland, which is where we've been talking to her in the last few minutes. Time for What's Up on Planetary Radio. Bruce Betts is the chief scientist. I'm still catching

myself because I still want to say director of science and technology, which I guess you really still are. It's just it's been folded into chief scientist. Yeah. Yeah. How are you? Pretty spiffy. How are you? I'm good.

I just I had a great time at Yuri's Night, which was Saturday the 7th here in L.A. It's still coming up. Of course, the real Yuri's Night is April 12th, that anniversary of Yuri Gagarin. Oh, well, I don't have to cover that in this week in Space History now. I should have told you ahead of time. First time ever they're doing a Yuri's Night party at KSC, at the Kennedy Space Center. It's the Space Coast, not to be confused with Space Ghost, party. And I'm sure it'll be fun.

I thought you said KFC, so i was you know looking forward to some food but okay ksc kindy space center i i get it extra crispy cosmonauts oh that's not that's not nice that's not nice at all i apologize quickly move on to the night sky i would recommend please all right evening sky. Venus getting a little bit higher each night shortly after sunset. Look for it in the west. Tuesday the 17th in the evening, the crescent moon will be fairly near super bright Venus. So check that out. A little constellation note.

Last few weeks for the year, for the season, we'll see it later in the year, to see the bright constellation Orion with, of course, Orion's belt. And check out the brightest stars in it are Rigel, which is blue, and Betelgeuse, which is red. A nice demonstration of differences in colors in stars. I'm sorry, Betelgeuse? I thought it was Beetlejuice, like the movie.

Don't say that again. I don't know. If someone is a master linguist and knows how it should be pronounced, let Matt know. Yeah, write to us at planetaryradio at planetary.org. Till then, I'm going with Betelgeuse. All right, let's move on to this week in space history. Oh, wait, we already did it. I will mention a couple other things, though. The 1970 Apollo 13 returned after its exciting mission,

and then 1972 Apollo 16 launched and headed off for a successful lunar landing. We move on to random space. Hey, hey, hey, Speck. That was full of character. That was a polite way to put it. So satellites, moons in the Jovian system are named for Jupiter or Zeus in Greek mythology. Jupiter, lovers and descendants. And he had a lot of them. So they're still, you know, they're good, even though we've got more than 60 moons. He got around.

He pulled. Yes, he got around. We move on to the trivia contest. I asked you what missions visited the Tiangong-1 space station, which just reentered a few days ago. How'd we do, Matt? I thought we would get like the biggest response ever because we were, for the first time in ages, offering, say it with me now, a planetary society. Rubber Asteroid. And it was a good response. Just not as huge as I thought. Maybe they've gone out of style. Although we have a lot of people here who are hoping to win. Anna Grunseff in Green Bay, Wisconsin. She said that three missions visited Tiangong-1, Shenzhou-8, 9, and 10, and that only the second and third had humans

on them. She right? That is correct. Fantastic. Anna, you are going to get the rubber asteroid and a 200-point itelescope.net astronomy account. And that rubber asteroid coming out of my secret stash that Bruce hopefully is still not discovered. Vicki Reed in Utah was among those who pointed out those two human missions, 9 and 10. And each of those had a woman on them. The first female taikonaut, Chinese astronaut in space, was Liu Yang. And Vicky says, go ladies. One of them, Liu Yang, who flew in June of 2013, who was pointed out that that was the 49th anniversary to the day of the first woman to fly into space, Valentina Tereshkova, who of course did that as a Soviet cosmonaut. Interesting. And I believe that Sally Ride launched on the 20th anniversary of Tereshkova's launch as the first American

woman in space. I think you're right. I'm pretty sure it was the 20th. Here was an interesting little space fact from, you might say a random space fact, from Mark Little in Northern Ireland. He said, you couldn't cook or use the bathroom on Tiangong-1. It was really just, it was tiny. Those services, along with a third bed,

were provided by the Shenzhou service module. Finally, this from Steve Wienel in Antelope, California. Hmm, sounds like there isn't enough of it left for a fourth visit, a fourth docking, which could have been made by a submarine. Yeah, I somehow think that'll be tough to hook up to. We're ready for yet another contest. What was the first astronomical object identified? So things seen in the night sky. Identified with a historical supernova explosion. So a supernova that was observed. Yeah, what was the first nebula? We're just going to go and simplify this.

What was the first nebula observed that was tied to a supernova that was actually seen by humans? Go to planetary.org slash radio contest. The supernova in the sky lighting up the sky. Yeah. And later, of course, became a nebula as that stuff expanded. There you go. Perfect.

Thank you for making that clear. I just want to make sure I understood. All right. You've got until Wednesday, April 18 at 8 a.m. Pacific time to get us this answer. And we will give you, ready, not a Planetary Society T-shirt. Nothing wrong with those. They're beautiful.

But a Planetary Radio T-shirt. Yes, we're back. beautiful, but a Planetary Radio t-shirt. Yes, we're back. And it's that design from the same guy at chopshopstore.com. If you go to chopshopstore.com slash planetary, you can see all of the Planetary Society goodies there and that sort of store within a store. It is the Planetary Radio t-shirt along with a 200-point itelescope.net account.

That's that worldwide non-profit network of telescopes and you can donate your account to a school or an organization if you wish or use it yourself. Maybe you'll see a nebula. That's it. All right, everybody, go out there, look at the night sky and think about if Jupiter or Zeus turned you into an animal and then into a constellation in the night sky, as supposedly happened, what kind of animal constellation would you want that to be? Thank you and good night. I don't have an answer for this one. I'm not going to pick my spirit animal or whatever it would be. enter the contest, or even if you don't enter the contest, what animal would you want to be before Zeus turns you into a constellation in the sky, there to live on forever in the hearts and

minds of people like Bruce Betts, the chief scientist for the Planetary Society, who joins us every week here for What's Up. Remember my conversation in our February 28th show with creators of A Message from Earth? I wasn't surprised to learn that this tribute to the Voyager Golden Record has been nominated for a Webby Award. You can vote for it or other nominees by visiting webbyawards.com. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its Earth-liking members. Mary Liz Bender is our

associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser. I'm Matt Kaplan, Ad Astra.