Planetary Radio • Feb 12, 2020

Another Goldilocks World and the Space Telescope That Discovered It

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Emily Gilbert

Graduate student in planetary science for University of Chicago

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Sara Seager

Astrophysicist and Planetary Scientist for Massachusetts Institute of Technology

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MaryLiz Bender

Cosmic Perspective

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Nicola Fox

Associate Administrator for NASA’s Exploration Systems Development Mission Directorate for NASA

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Mat Kaplan

Senior Communications Adviser and former Host of Planetary Radio for The Planetary Society

The planet has the less than romantic name TOI 700 d, but its discovery has generated passion among those searching for another Earth, including Emily Gilbert. The graduate student is lead author of a paper about the new world. TESS, the Transiting Exoplanet Survey Satellite, played a key role in its discovery. MIT planetary scientist and astrophysicist Sara Seager returns to tell us about this powerful tool and more. We also visit with the leader of NASA heliophysics research as she awaits launch of the Solar Orbiter. Look out! The rubber asteroids are back on What’s Up!

TOI 700 d Artists' Illustration
TOI 700 d Artists' Illustration TOI 700, a planetary system 100 light-years away in the constellation Dorado, is home to TOI 700 d, the first Earth-size habitable-zone planet discovered by NASA's Transiting Exoplanet Survey Satellite.Image: NASA Goddard Space Flight Center

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Matt Kaplan: [00:00:00] Another Goldilocks World and the powerful Space Camp that helped us discover it, this week on Planetary Radio.

Welcome. I'm Matt Kaplan at the Planetary Society with more of a human adventure across our solar system and beyond. We've got so much for you this week, planetary scientist and astrophysicist, Sara Seager, is back to tell us about TESS, the space telescope that is revealing new exoplanets. One of those worlds is in the fabled habitable zone of its Dwarf star. We'll learn about it from Emily Gilbert, the graduate student who served as lead author of one of three papers about TOI 700 d. We'll also hear about the beginning of a mission to learn more about our own star, and out there beyond it all, waits Bruce Betts with this week's what's up, including the return of the rare and [00:01:00] dangerous rubber asteroids. Sounds like a lot, but there's so much more going on in space exploration. Here are a few headlines from the most recent edition of the down Lake collected by Planetary Society, editorial director, Jason Davis.

Welcome home. NASA astronaut, Christina Koch is back on Terra Firma after 328 days in low earth orbit. She now holds the record among women for the longest single space flight, and she says she looks forward to someone else breaking that record. NASA's Mars 2020 Rover has been packed up and shipped off to the Kennedy Space Center. The launch window opens in July and runs into August. And the Russian Space Agency, Roscosmos reports that all 13 science instruments have been installed on the Lander that will carry the European Space Agencies, Rosalind Franklin Rover to the Martian surface. Same launch window as the NASA mission, of course. You'll find these [00:02:00] stories and more at link, and soon you'll find much more including great space images, cool facts and announcements from the Planetary Society and it will all be delivered to your inbox. Stay tuned.

The sun is about to gain a new satellite. The Solar Orbiter Mission was launched from Cape Canaveral on the evening of, how appropriate, Sunday, February 9th. The joint ESA, NASA mission will eventually go into a more or less polar orbit around our star revealing those poles with cameras for the first time. Former Planetary Radio associate producer, MaryLiz Bender now with Cosmic Perspective was there to watch the Atlas five lift off. Here's a report she shared with us just two days before this launch.

MaryLiz Bender: I just got back from Kennedy Space Center after the Prelaunch NASA Science Briefing for the Solar Orbiter mission. There, I found a room of very excited scientists. Among them [00:03:00] was one of my favorite people to talk to, Nicky Fox. She is the director of the division of Heliophysics at NASA. Nicky has worked closely with a Solar Orbiter team and she was also the project scientist of the Parker Solar Probe Mission. We last talked just after the Parker Solar Probe launch in August of 2018, and now I am so glad to have had the chance to talk to her again just a couple of days before the launch of its sister mission, Solar Orbiter.

Nicky Fox: I was extremely excited the last time we talked cause I just watched the Delta IV Heavy lift off the pad and I was in a very exc- I think you actually introduced me as a very excited Nicky Fox, and I was indeed. Uh, I was over the sun with excitement with the Parker Solar Probe launch and equally as excited now to see Solar Orbiter go on Sunday.

MaryLiz Bender: You remember? That's amazing. That sparks my memory. You said, "I'm over the moon, I'm over the sun." [laughs].

Nicky Fox: That's true. I... and I was.

MaryLiz Bender: [laughs].

Nicky Fox: I describe myself as a launch junkie. Um, I... this is [00:04:00] the most exciting thing for me. Um, I think I got the bug, uh, very early. I worked on the, the Van Allen Probes and I, I was very blessed to work with the team very closely and, uh, see all that last minute preparation. Uh, obviously with Parker, I was down here for the last six weeks working with the team and so I know what they're going through, so even though I haven't had the opportunity to, to be in the clean room with Solar Orbiter, I know the excitement that this team is feeling. And so yes, uh, we cannot wait to see that, that rocket lift off the pad.

MaryLiz Bender: Yes. I say this all the time. So, I'm a launch junkie and I don't have any intimate connection really with this thing except to feel like humanity's doing this amazing thing together. Right? But I always say that watching a night launch is like watching a sun rise in the middle of the night.

Nicky Fox: I- it really is. And, and you know, you see the spectacle of it, then you, you hear, and then you feel the pressure, and there is, you know, that. Yes, it's wonderful. Um, daytime launch is a really nice... I don't wanna knock our daytime launches, but man, [00:05:00] the sight of that thing going at... uh, during the night is just amazing.

MaryLiz Bender: Can you tell me about your involvement with this particular mission? I know you answered a lot of questions today about Parker Solar Probe, really great data coming back from that right now, but what has been your role, um, in the Heliophysics Division for Solar Orbiter?

Nicky Fox: Well, so I started working with Solar Orbiter a number of years ago when I was still uh, the Parker Solar Probe project scientist, and I worked very, very closely with Daniel Mu- Mueller, um, and we, we really wanted to collaborate and we wanted to, to, to get these missions working together because they are so much better as a team. And so I've had a long involvement with the Solar Orbiter team, but since I moved down to NASA Headquarters, I'm sort of in charge of making sure that everything is perfect for launch on Sunday. And so I've worked extremely closely with our counterparts at ESA, uh, with, with our folks here at NASA's Launch Service Program with ULA, and just making sure everything is ready to go.

NASA has a couple of instruments that are, are flying on Solar Orbiter and... but it's, it's more than just those instruments. [00:06:00] It's really that, that team of 10 instruments working together, and so, uh, the team here, um, all of the different, the stakeholders, all of the partners just all pulling in the same direction for launch on Sunday.

MaryLiz Bender: I really loved the vibe of the excitement over the international collaboration on the science, especially, how do those decisions get made? Or how do you all talk to one another and say, "Hey, we've got something over here we think you'd like to work on?" Or, you know, how, how do people raise their hand to work with NASA and ESA?

Nicky Fox: It's pretty much like that. We work very, very closely with all of our partner agencies and we, you know, we, we meet together and we say, "Hey, there's this opportunity, would you like to take part in it?" Um, so there are lots of collaborations with Heliophysics, the sort of notable ones, the Ulysses and SOHO, uh, now of course, uh, Solar Orbiter adding to that legacy. And so, yeah, i- it really is just a, "Hey, there's an opportunity. Would you like to join us?" And we're always looking for ways to, to work together, uh, to really do things better. That's exactly how it happens for Heliophysics. [00:07:00] The thing I love about it is, honestly, wherever you go in the Solar System, we wanna go with you. We will take data from anywhere. We work really closely with our planetary colleagues, um, and now with our astrophysics colleagues as to, "Hey, what is the information we're learning about ASTA, how can we help you apply that to other stars?" And so, you know, I just love science.

MaryLiz Bender: Hmm.

Nicky Fox: Um, the sun has been... it's, you know, it guides us, it's there every day. We are sometimes argue about, which was the first branch of science. I always say it's Heliophysics because everybody looked up at the sun and stared at it and wondered what it was. And so we are now sending missions up close to really explain what's happening at our star.

MaryLiz Bender: It emits the source of life, right? I mean, so essentially you are studying almost every branch of science when you study the sun.

Nicky Fox: Absolutely. Yes. We put years and years into these missions. Daniel said he's working on this missions for 13 years. Parker Solar Probe, I'd worked on it for eight when it launched. You know, I mean there's... you've, you put a lot of work into it and it's not like we have another mission just sitting there that if something goes wrong [00:08:00] here we can launch it, this is our one shot at doing this. And so, yes, we're all nervous, but it's really just pure excitement. We can't wait to see Solar Orbiter join Parker Solar Probe, their sister, sister missions. We've always thought of them like that and we can't wait for them to get up there and start working together. But, as always, it's a great time to be a hyliophysicist.

Matt Kaplan: Cosmic Perspective's Mary Liz bender talking with NASA's Nicky Fox just two days before the beginning of the Solar Orbiter Mission.

The legacy of the Kepler Mission lives on. as of mid January, more than 4,000 exoplanets have been confirmed, and most of these were discovered by that space telescope. There are thousands more waiting for confirmation and now the list of worlds is growing, thanks to Kepler's daughter TESS. We'll focus in a few minutes on just one of these, a roughly earth sized planet known as TOI 700 d that orbits in its stars habitable zone. But first for [00:09:00] an overview of TESS and the current state of exoplanet research. I called on professor Sara Seager. She is an astrophysicist and planetary scientist at MIT where her team teases evidence of exoplanets from the data returned by TESS. Sara, welcome back to Planetary Radio. Uh, it's been a while since we've talked. In fact, well, we may mention those previous appearances because they'll be pretty relevant to today's discussion, but it's great to have you back on the show.

Sara Seager: Thanks, Matt. Great to be back.

Matt Kaplan: Let's talk about the transiting exoplanet survey satellite before we get onto other things. As I mentioned to you a moment ago, we have not talked about in depth on this show with... it's come up because it's done some great work, but we haven't brought it up in depth since the launch, which now was nearly two years ago. Has TESS been meeting everybody's expectations?

Sara Seager: Absolutely. Tess has, I would say even been exceeding expectations.

Matt Kaplan: That's great.

Sara Seager: Yeah. [laughs].

Matt Kaplan: I [00:10:00] see a... saw in looking at the website that it was going to cover the sky, what, 200,000 stars in two years, but, but we're not talking about it ending its mission in, in April, which would be the second year anniversary, are we?

Sara Seager: No, not at all. In fact, TESS has been extended. It has passed a review at NASA to get an extended mission, so it will be going for another two or three years, and honestly TESS could go on indefinitely. It's orbit is incredibly stable and it doesn't need much fuel. It really doesn't need much at all to keep going.

Matt Kaplan: Is that especially good news? Because, I mean it... the longer you stare at these stars and the planets that pass in front of them, the better off you are.

Sara Seager: That's right. It's better to stare at an object longer because the more transits we see, the more planets we can find. Right now, TESS is mostly finding planets that have periods, their year, the time it takes to go around their star is less than about a month, so it would be way better if we could stare at the same stars, you know, over and over again and find much longer [00:11:00] period planets. Also, if we can stare more often, we can bing the data down and we can look for smaller and smaller planets. Finally TESS's prime mission covers about 70% of the sky. During the extended mission, TESS has a chance to fill in the rest of the sky.

Matt Kaplan: That's great. Did we learn the basics of this through Kepler and the great work that that, uh, immediate ancestor of TESS did?

Sara Seager: We did. Kepler was so incredibly pioneering. It will be a legacy for all time. A lot of what we do on TESS builds directly on, on Kepler. The data reduction techniques we use, the data pipelines even, and all of our strategies and methods.

Matt Kaplan: So out of this 200,000 stars in this initial period of operation by TESS, how many roughly earth sized worlds in their habitable zones, uh, do... can we expect to find out of, out of this data?

Sara Seager: It's true TESS is looking at [00:12:00] 200,000 stars at two minute cadence in the prime mission, but did you know that TESS is also looking at millions more stars? Millions.

Matt Kaplan: No.

Sara Seager: It is.

Matt Kaplan: Wow.

Sara Seager: Because the team found a very clever way to be able to down link what we call full frame images. You know, it's so hard to send data back to earth, it's very huge bottleneck and so we can't send all the stars in the field of view, but we're able to in the data onboard, to stack the data and send 30 minute cadence down to the ground. And so in addition to studying those 200,000 special- specially chosen stars, we can also look at so many more stars.

Matt Kaplan: That's fantastic. All right, well the more you look at, the more of these, I hesitate to use the phrase, but I will, earth like planets we're going to find, right?

Sara Seager: You do hesitate for good reason because-

Matt Kaplan: [laughs].

Sara Seager: ... we really want to reserve Earth-like for the true earth twin, the earth size, earth mass planet orbiting a sunlight star in a one year period. TESS, it turns out is purposely designed to be very, [00:13:00] very sensitive to small planets orbiting very small stars. They're very different from our sun, M dwarf stars among the most common types of stars that we have.

Matt Kaplan: So MIT, one of many institutions, but the, the lead institution in many ways for dealing with, uh, TESS data, I mean, what's it like there? Is it. is it a busy place, is... a you and your colleagues search for these worlds?

Sara Seager: It's very busy, very busy and it's actually mostly young people getting, getting the hard work done. Here at MIT, we're responsible for finding the planet candidates that go out to the community so people can work on them. Here we actually brand objects, TESS objects of interest. So whenever you say TOI this, TOI that, it actually came from my team's work here. The computers do all the hard work, there's the official data pipeline out at NASA Ames that works on the 20,000 objects per month at two minute cadence, and here at MIT, we run our so-called quick look pipeline on hundreds of thousands of stars that come at 30 minute cadence [00:14:00] and the computers churn away and they present us with a long list of what they call threshold crossing events. And it's our job here using more computer programs to find out which ones are worthy of being designated a TESS object of interest. And at the very end of that process, it's gonna sound funny to you, but we actually have humans, we call it [inaudible 00:14:19].

Matt Kaplan: [laughs].

Sara Seager: Yeah. We have [inaudible 00:14:20], groups and we meet every few say from one to three o'clock and it's like a rotating group of trained experts, and we literally look through the data, and there's data products that come with it and we try to decide whether it's worth putting it out to the community and giving it an official TOI stamp so people can look at it further.

Matt Kaplan: That is so cool. I have to think that over the years that we have been finding exoplanets, you and other folks like your team there at MIT have gotten better and better at this?

Sara Seager: Definitely, you can say that finding planets by transits is actually a very mature method. It is standard operating procedure.

Matt Kaplan: Your [00:15:00] Seager equation, uh, a twist on the famous Drake equation, you, you really consider with this only these habitable zone and sized planets, right? I... and, and I, I noted that one of your factors in the equation... by the way, we'll put up a link to this somewhere online, maybe through your own website, one of the factors calls for stars that are quiet and, and that's gonna come up again when we talk to, um, Emily Gilbert in a minute but, but tell us why that was an important factor to include.

Sara Seager: At the moment, we are struggling to find planets around variable star... very highly variable stars. It turns out that stars, even our own sun because of its spots, vary with time. Uh, many of these [inaudible 00:15:45], stars, they're just so variable. It's like, "Wow, what happened?" And the star is not just constant with time. Every time TESS takes an image of it, it's brightness is slightly different and this is usually due to spot, spottedness of the star and its stars are rotating so [00:16:00] different spots are forming and are coming in and out of view. It's sort of a just a selection effect. It's a problem with nature that the noisy stars are hard for us to find planets around and they'll also be hard for us to study planets around later.

Matt Kaplan: So this isn't a reference to, uh, low activity by the star in terms of like solar flares, which you know I think is one of the things we, we will talk with Emily Gilbert about because that dwarf star around which TOI 700 d is revolving uh, is a, is a fairly quiet star, but, but that is another issue, right?

Sara Seager: Right. These spotted stars, we think, correlate with stars with flares-

Matt Kaplan: Mm-hmm [affirmative].

Sara Seager: ... so they're just generally active all around and these flares are something else. I mean, apparently Proxima Centauri, our very nearest star to our earth, to our solar system, which has a planet around it, apparently that flare, that if you were looking at it at the right time from a truly dark sky, you would have seen it brighten.

Matt Kaplan: Oh my, that's bad news. [laughs].

Sara Seager: I know. Right. [00:17:00] I don't know, we're really not sure. Maybe, maybe there's intelligent beings on planets orbiting stars that flare, and they're looking at our sun and their version of the Drake equation says, noisy star. Maybe they're thinking, "Now there's no way those folks can get energy. How do they recharge their power grid?" [laughs].

Matt Kaplan: [laughs].

Sara Seager: We really don't know.

Matt Kaplan: Yeah, we don't know what we don't know, in fact. With that in mind, you came on in 2017 because you were part of the announcement of the discovery of those worlds around the star known as TRAPPIS 1, three years later, are we much closer to, to finding a planet that has signs of possible life?

Sara Seager: Yes and no. That's the scientist answer always.

Matt Kaplan: Yeah.

Sara Seager: We're no closer in terms of having data in our hands. I don't have a spectrum that I can analyze and give you a yes or no on that. We're still closer because more methods have developed, more [00:18:00] candidate bio sinker gases have been thought of, and the James Webb is closer to launch, so we're definitely closer in that sense, but no, we can't... we don't have anything solid to report on at the moment.

Matt Kaplan: I'm glad you mentioned the James Webb. The JWST, James Webb Space Telescope, of course. The first time you came on the show, we met each other at Northrop Grumman right next to where that great infrared telescope was coming together, but that was more than five years ago. It sounds like you're still very much looking forward to this, uh, powerful new tools starting to do its work.

Sara Seager: Not just me, but our entire exoplanet community's waiting, literally waiting and excitedly expectantly wanting James Webb to be launched and be taking data. You would not believe how many people are in this field right now, even as compared to 2017.

Matt Kaplan: I know, sadly we've got this, this little, uh, interruption of at least some, uh, infrared data because I mean we were just talking about it [00:19:00] last week on this show, we've lost the Spitzer Space Telescope, that other infrared, uh, instrument that has been doing such great work out there in space. What does that mean for, for you and, and for the exoplanet community?

Sara Seager: Spitzer was a workhorse for exoplanets. I would wish we could look at the glass as half full in this case because Spitzer was supposed to stop operating, I wanna say five to 10 years ago. It's incredible how the scientists and engineers were able to keep Spitzer working and it's been so great, recently, mostly for validating exoplanets, by looking for them from space or by trying to characterize them by their secondary clips or by what we call their thermal phase curves. Uh, it's definitely sad to see Spitzer wrap up.

Matt Kaplan: Hmm. All right. Well, like we said, if everything goes well and NASA's still hoping that this happens next year or 2021, we'll have the JWST out there. Do you have some confidence that with this powerful new tool that you will start to get [00:20:00] those spectra from these planets that, that might tell you, "Hey, look, there's some oxygen or, or some other sign that could be an indication of life?"

Sara Seager: Well, yes and no, I know, yes and no. [laughs].

Matt Kaplan: [laughs]. Once again?

Sara Seager: I'll, I'll say that everyone, including myself, is working as hard as possible to make sure that, you know, in the limited lifetime of the James Webb Space Telescope, that we're able to get all the data we need. It's a bit tricky because we don't have any earth like planets that the James Webb can observe. It doesn't have the capability, nor do we have any that we will be able to work with and understand in detail. We're kind of going blind in a way because all these planets around M dwarf stars, they're very different from earth and we really, um, we're working hard to expect the unexpected and to plan for what might be out there. So we're trying to make sure that as a community we cover all the right planets, at the right wavelengths, and that we just have that great data to work with. So we're hopeful that we'll find it, but, you know, life has to be there.

Matt Kaplan: Yeah.

Sara Seager: We have to [00:21:00] keep the right planets. Life has to be generating gases that accumulate in the atmosphere.

Matt Kaplan: You know, the debate goes on as to what data telescopes may be able to return, spectra, that would actually say to us, "Yeah, this could be life," as opposed to some non biological process. Do you see progress in that area as well?

Sara Seager: Yes, there's been a lot of progress, somewhat to the negative in a way, because oxygen is our favorite bio signature gas, uh, here on earth. Our atmosphere is filled with oxygen to the 20% by volume. But without life, without plants and photosynthetic bacteria, we'd have no oxygen. And in the last few years since we've talked, people have been working hard to come up with false positive scenarios. What if you found oxygen and it wasn't related to life. So people are working on scenarios with corroborating gases in the atmosphere. And it's funny because someone comes up with a new scenario where oxygen could be a [00:22:00] false positive, and then a couple of years later, someone shoots that scenario down.

Matt Kaplan: [laughs].

Sara Seager: So we're making progress here. I think we'll be, I think we'll be ready.

Matt Kaplan: But it's good science, right? I mean, you want people to be shooting those down?

Sara Seager: We want people to be shooting those down, we want to know what we need, what information we need. It's tough, though. I liken it to a forensic crime scene. You're gonna have clue, you're gonna have evidence, but you've got to put the story together.

Matt Kaplan: Wow. Yeah, it is a detective story, isn't it? Before we go, as I said, we're gonna be talking to Emily Gilbert at the University of Chicago uh, in just a moment or two. And, of course, she is just a grad student and yet she was the lead author of one of these three papers that, that you are also a co-author of, uh, do you see this as, as something very positive that we're seeing, uh, grad students and sometimes even undergraduates, uh, popping up as people who are doing, making great contributions to, uh, our knowledge in planetary science?

Sara Seager: Yes, TESS is a wonderful dataset [00:23:00] and there's so many planets, so many stars. It's just fantastic to see so many young people like Emily Gilbert really jumping on the data, and it's great to see them be able to find and work on such amazing new planets.

Matt Kaplan: Sara, I, I sure look forward to that, uh, launch and Firstlight from, uh, the James Webb Space Telescope and I don't think I will wanna wait longer than that to, uh, have another conversation with you. Maybe it'll happen before that, but uh, can I get you back on the show when, uh, when that big thing unfolds, fingers crossed, out there in space?

Sara Seager: Absolutely.

Matt Kaplan: Thank you, Sara. Great to talk to you.

Sara Seager: Thanks, Matt.

Matt Kaplan: That's Sara Seager, professor of planetary science and physics at MIT and a MacArthur fellow among her other honors. She is, uh, waiting for more data which is arriving, but uh, we'll see far more of it when the James Webb Space Telescope begins to do its work.

We're far from finished with this week show. Just pausing for a minute to remind you that there's much more [00:24:00] out there across the expanse for us to discover, which is a not too subtle way to tell you that we are once again brought to you by Amazon Prime Videos, the Expanse, Season Four. I just had a listener asked me if she should start by reading the books or just diving to the TV series. I love the books and highly recommend them, but the show is so very good and so true to the books where it matters that I'm just fine with anyone who wants to start with Amazon Prime Video and I remain indebted to Jeff Bezos for rescuing the show when it was dropped by sci-fi.

To review, season four finds the crew of the Rocinante exploring worlds beyond the wormhole like Ring Gate. Actually one world in particular that offers riches to any settlers from earth, Mars, or the belt who can reach it and survive. That survival is made far less likely by the magnificent ruins of a long dead alien civilization. Great [00:25:00] characters, spectacular action and vistas and human nature at its best and worst. That's the Expanse with episodes streaming now on Amazon Prime Video.

We've learned about TESS and related efforts from Sara Seager, let's go now to the University of Chicago to learn about just one newly discovered world. Three papers about it were published just a month ago and the first of these featured our next guest as its lead author. Emily Gilbert is a graduate student working toward her PhD. Emily, thanks very much for joining us on Planetary Radio and congratulations on the publication of this paper about this uh, new world, which, who knows, may not be so different from our own. Uh, again, thanks for joining us.

Emily Gilbert: Thanks so much, I'm so excited to be chatting with you.

Matt Kaplan: Tell us a little bit about TOI 700 d. I, I hope that someday it'll get a, a, a more romantic name than that, but I guess that'll, that'll do for now. [00:26:00] We just last week in our tribute to the Spitzer Space Telescope, we were talking about the TRAPPIST 1 worlds, now this one, your paper and the two others about it only just uh, were published at the beginning of January, toward the beginning of January. There still aren't that many of these worlds that are in the so called habitable or our Goldilocks zones, are there?

Emily Gilbert: No, I think we have somewhere around a dozen planets that are roughly earth sized and in the habitable zone.

Matt Kaplan: I guess this would be the latest edition?

Emily Gilbert: Yes. As far as I know, this is the most recent one to come out.

Matt Kaplan: Can you tell us about this, this world?

Emily Gilbert: Yes. So it's around an M dwarf star. So an M dwarf star is a smaller and cooler and rudder star than our own sun, and so what that means is that it puts out less light. So in order to be the same temperature as earth, the habitable zone is much closer in. So this planet actually orbits at star once every 37 days. So it's a very close in orbit. One [00:27:00] thing that we think is unusual about this planet is that we expect that it's tidally locked. So what that means is that the same side of the planet always faces the star, like the moon does with earth. So you always see the same side of the moon from earth. We think that the same side of the planet always faces the host star TOI 700.

Matt Kaplan: Hmm. I wanna come back to that fact, but um, you also have noted some interesting things about the star that TOI 700 d, uh, revolves around, I guess it's not as active as a lot of other dwarfs in its class?

Emily Gilbert: Yes. So M dwarf stars are known for being historically very, very active, so you'd see things like stellar flares, so big increases in the amount of light that the star is emitting over time. This could be really, really harmful to a planet, but luckily, both for detecting the planet and in terms of planet habitability, we don't see any flares in the entire 11 month TESS light curve.

Matt Kaplan: Well, that's good news, especially considering how close it has [00:28:00] to be, to be in the habitable zone, what else is happening in that system? I, I, I've read about at least one other world.

Emily Gilbert: Yes. So the system has three planets, total. So the naming convention for exoplanets goes that the star is body a in the system. So there's TOI 700, the host star, and then TOI 700 b, which is basically earth radius size planet orbiting once every 10 days. And then there's TOI 700 c which orbits every 16 days, and is closer in size to Neptune, and then TOI 700 d is the third planet we know, the outermost planet and that's the one that's in the habitable zone.

Matt Kaplan: Have we ruled out the possibility of still more planets, uh, beyond, uh, 700 d or, or will that depend on more powerful instruments?

Emily Gilbert: There's the possibility that there could be more planets in the system. Uh, TESS will observe this system again for another year starting in July, so we're looking forward to more data there, we'll see if there's anything else. And there's also the [00:29:00] possibility that the system hosts planets that don't transit. We are detecting the planets using the transit method, so as the planet passes between us and the star, it blocks some amount of light from the star and you see a dip in the amount of light over time. That's called a light curve. If a planet is inclined relative to the system, it might not transit from our point of view, and so we wouldn't be able to detect it through this method.

Matt Kaplan: We talked about this some last, uh, last week when we, uh, considered the TRAPPIST 1 worlds, which-

Emily Gilbert: Mm-hmm [affirmative].

Matt Kaplan: ... uh, it was just a matter of luck, I guess, that all seven of those planets, uh, are in the plane from our viewpoint where they uh, cross in front of their star and, and so we know about these three now, right? At a, uh, TOI 700?

Emily Gilbert: Yes, definitely very fortuitous for the TRAPPIST system. It's a really, really cool system.

Matt Kaplan: Let's talk about this first paper that you're the lead author of. It's an amazing... it's almost a who's, who of people working in this area among your co-authors, uh, people that have been on this show, Courtney [inaudible 00:29:58], Lucianne Wolkowitz, Lisa [00:30:00] Kaltenegger, Sara Seager, it's quite a group that has been pulled together for this work that you lead.

Emily Gilbert: Definitely. Also, I'm really excited, all the people you named are women, which is really cool.

Matt Kaplan: Yes, absolutely. And I noticed that for all three of the papers that it looked like the majority of uh, people who worked on, on studying this planet, uh, were women. And, and that certainly seems like it fits the trend we've seen in planetary science.

Emily Gilbert: Yeah. It really makes me happy. It was a massive group effort in order to get all of the data and all of the information that we needed. Um, so we did a whole bunch of ground-based followup to both characterize the host star because a lot of the planet parameters are dependent on the parameters from the star itself, and then also to make sure that the transit signals were real. And so, we wanted to know that what we were seeing was planets and not something induced by the spacecraft or something like a background eclipsing binary that could be masquerading as a planet signal.

Matt Kaplan: How high is your confidence now that, uh, what you believe this [00:31:00] planet to be is, is actually the case?

Emily Gilbert: Well, that leads us into uh paper two uh-

Matt Kaplan: Yeah.

Emily Gilbert: ... just the Spitzer confirmation. Using all the ground-based information, we were able to rule out astrophysical false positives and the Spitzer confirmation allowed us to rule out instrumental false positives. So that helped us to confirm the planet.

Matt Kaplan: Say something about the array of instruments that is av- available now. I mean, you've, you've talked about the use of ground-based telescopes and Spitzer, of course, which sadly is now out of action as of a couple of weeks ago, and TESS, uh, which is still very much uh, doing, it's workup there, carrying on the legacy of the Kepler Spacecraft before it, do you feel fortunate to be living in this time when, uh, we can do this work that simply wasn't possible, not very many years ago?

Emily Gilbert: Oh, definitely. The field of exoplanets is a very new young field, at least relatively speaking, in terms of the millennia of astronomy studies. [00:32:00] And it's really, really incredible the things that we can do nowadays.

Matt Kaplan: And how. let's go back to 700 d you said it's tidally locked, the third paper that was presented, uh, along with yours and the other one sort of looked at that and, and came up with some models, are you familiar with that work?

Emily Gilbert: Yes. So that work was done by Gabrielle Suiza, and a whole bunch of her collaborators. They were looking at different climate states of TOI 700 d. they picked a bunch of different compositions and pressures, and just model the planet under these conditions to try and see what would happen. There were two big takeaways from the paper, some good news, as well as some bad news. So I'll start with the bad news, is that if the planet does have an atmosphere, it will likely be very difficult for us to detect it with James Webb. So James Webb won't be the one to characterize this planet for us.

Matt Kaplan: Too bad.

Emily Gilbert: I know. I was, I was really sad when I saw. [laughs].

Matt Kaplan: [laughs]. [00:33:00] Now, let me... before you go onto the good news, why is that? I, I mean, JWST will be so much more powerful than any infrared tool that we've had up there before. What is it about the atmosphere of this world that... and maybe its relationship to its star that may keep us from characterizing it?

Emily Gilbert: The strength of the signal is about the same level as the JWST noise floor, so you'll end up just losing the signal and the noise. But I think this is actually true of a lot of M dwarf planets that James Webb is going to look at, and the problem here is that the atmospheres are so small. Like, if you look at pictures of earth taken by astronauts on the International Space Station, you can see that very thin blue line that is earth's atmosphere.

Matt Kaplan: Yeah.

Emily Gilbert: [inaudible 00:33:44], what we're trying to detect for planets a hundred light years away, so it's a really, really precise rep measurement that's really hard to detect.

Matt Kaplan: Well, I'm still gonna keep my fingers crossed because as with so many of the other space telescopes and ground-based telescopes that have uh, [00:34:00] seen first light in the last, Oh, I don't know, 30 years, uh, they ended up being capable of doing much more than we might've expected. So out of ignorance, I'm not giving up hope.

Emily Gilbert: [laughs].

Matt Kaplan: What's the good news that you said you have?

Emily Gilbert: Yes, the atmosphere is extremely stable. So, under a whole bunch of conditions, the planet was able to maintain it's atmosphere. This bodes well for prospects of habitability, which is really good because it's tidally locked and one side always face the star, has very interesting atmospheric heat redistribution, and what ends up happening if the planet is to have an atmosphere like ours, all the clouds converge on one side of the planet. So if you take a look at some of the artist's interpretation of what the planet looks, you'll see a giant cloud spot and it's very, very cool.

Matt Kaplan: We'll post uh, links to some of those images and the press release, uh, which is how I learned about this uh, great work by you and the other two groups. About this world, uh, 700 c, the one that's closer in size to Neptune, [00:35:00] you mentioned in your paper that uh, while 700 d may not be a great candidate for study by uh, James Webb, maybe 700 c is?

Emily Gilbert: Yes. So you could probably observe the atmosphere with planet c. um, so it's a much larger planet, so we expect that similar to the gas giants in our outer solar system, it doesn't have a surface like earth and then the atmosphere on top of it. It's just a large ball of gas, and therefore it's much easier for us to probe the atmosphere.

Matt Kaplan: I should note also that, that you are a co-author in the other two studies that were published at the same time.

Emily Gilbert: Yes. So I worked very closely with both Joey Rodriguez, the lead author of the Spitzer paper and Gabriel Suiza the, lead author of the atmospheric modeling paper. Uh, we all kind of joined forces to kind of divide and conquer on some of the different aspects of this work. And on top of that, we each had a whole host of co-authors helping us along the way.

Matt Kaplan: Huge crowd, uh, which is worth looking at as well. I [00:36:00] wanna note, because I like to do this, that, uh, you're a grad student, uh, there at the University of Chicago. This was not something that used to happen, where a grad student was, um, given the, uh, the right to be listed as lead author on a paper of such significance. That's another important development, isn't it?

Emily Gilbert: Definitely. I am so, so grateful for this opportunity to have led this paper. Definitely wanna thank my small army of advisors, Tom, Joshua, Lucianne, who supported me through all of this, gave me this opportunity, and point out that Gabby, the author of the third paper is not even in grad school yet. So-

Matt Kaplan: Hmm.

Emily Gilbert: ... it's truly amazing the opportunities we're giving to students now.

Matt Kaplan: And I think it, it, it denotes a, a certain growth in generosity from uh, more established faculty members who in the past, I'm not naming names, but decades ago, might've, uh, you know, pushed your name down in the list if it had been there at all, there's one more person that I wanna [00:37:00] bring up. I don't know if you've met Alton Spencer, but my goodness, it's impressive enough to be talking to a grad student who is a lead author, but he's a high school student?

Emily Gilbert: Yeah. I haven't met him personally, but we have a whole bunch of interns who come every year at Goddard. I was actually an intern about five years ago. It's great that they let them just jump into projects, do super cool research and it's really exciting for them.

Matt Kaplan: As I understand it, he went through the calculations and, and found a problem with them, and because of that, suddenly this world looked much more promising.

Emily Gilbert: Yeah. So he was working with Joey Rodriguez, the lead author of the second paper, and Andrew Vanderburg who were working together, um, and it was actually someone on our team, Josh Sleeter, who realized the same mistake. The star was put in with solar parameters, so that meant the star was bigger and hotter and therefore the planet was bigger and hotter. And then, if you put in the correct stellar parameters, you end up with an Earth-sized planet in [00:38:00] the habitable zone.

Matt Kaplan: So, I mean just by accident, they considered it... the characteristics of our star, the sun rather than uh, TOI 700.

Emily Gilbert: I think it was just the default if there were no stellar parameters.

Matt Kaplan: Ah. Fascinating.

Emily Gilbert: [crosstalk 00:38:15], parameters by mistake.

Matt Kaplan: Thank goodness that got caught. [laughs].

Emily Gilbert: Yeah. [laughs]. it was actually included in, um, Courtney Dressings, M dwarf survey, and I think that's how Josh caught it. He knew it should be an M dwarf based on this survey, and then saw that it had solar parameters and knew that something was up.

Matt Kaplan: This is another proof of, uh, the importance of community, uh, and many people looking at all sorts of things that are happening across the universe. Um, thank goodness for all of this. I guess otherwise, uh, we might not have seen these three papers telling us about this possibly Earth-like world.

Emily Gilbert: Yes, there was definitely a very, very good caption.

Matt Kaplan: So where do you go from here? I mean, you al- already said that uh, TESS is going to be going back to staring at [00:39:00] this section of space and, and this system, uh, w- what about you? Is this actual planet search and, and learning more about them? Is this something you're going to be doing more of in your career?

Emily Gilbert: Yes. So I, for my PhD thesis, am studying M dwarf planet habitability in a very, very broad sense. Um, so I'm also looking at M dwarf activity while TESS is, by name, a planet finding mission. It's also very good for studying stars. So I'm using data to look at stellar flares and see how those trends vary across stellar types, and also continuing with the planet searches. And then, ultimately I'd like to combine these and see how these flares could affect planets and planet habitability.

Matt Kaplan: Well you've got plenty to study out there and um, I hope that this is just the first of uh, what will be many, uh, conversations over a long and, uh, equally successfully career, Emily. Um, congratulations again on this great work [00:40:00] and thank you for taking the time to talk about it with us.

Emily Gilbert: Thank you so much for having me.

Matt Kaplan: That's Emily Gilbert. She is, as you heard, a graduate student in the department of astronomy and astrophysics at the University of Chicago. And she is the lead author of the first of these three papers about the TOI 700 system and in particular TOI 700 d, the one that, uh, is in the habitable zone, at least the one that we know about so far.

Time for what's up on Planetary Radio. Bruce Betts is the chief scientist of the Planetary Society, among other things, I... you know, he runs the LightSail Program as well. I did have a listener say, "Hey, we haven't heard about LightSail in a while. You wanna give us a little thumbnail update?

Bruce Betts: It burst into flames and rose from the ashes.

Matt Kaplan: [laughs].

Bruce Betts: No, [laughing], I'm sorry.

Matt Kaplan: No, that was Phoenix. [laughs].

Bruce Betts: That was uh, Phoenix. I, I get LightSail 2 confused with mythological characters.

Matt Kaplan: [laughs].

Bruce Betts: A little delusional that way. Uh, [00:41:00] LightSail 2 is doing well. It's uh, still orbiting. You can check it out at a, you can follow links to mission control page to see the orbit and how it's varying. We had a nice blog a few... very few weeks ago by Jason, uh, Davis explaining, tied to a technical paper that was led by uh, Purdue grad student, Justin [inaudible 00:41:25], that really... we're really getting to where we understand this new thing, which is flying a solar sail on earth orbit, and what the different factors are that go into it, and we're learning from it.

And I'm super happy because, uh, various things have worked out and gotten resolved in glitch slams so that we're getting a lot more pictures. So-

Matt Kaplan: And they're gorgeous. They're beautiful.

Bruce Betts: Those will be getting released, uh, in the coming, coming days and weeks, and you'll be able to check them out, but it's uh, it's, it's cool. So [00:42:00] we're learning stuff about solar sailing and we're getting pretty pictures, and what more could you ask for?

Matt Kaplan: Not much. This is great. It's, it's nice to hear that we're learning stuff that, who knows, maybe useful to other people.

Bruce Betts: Yeah. Well, that's the goal. We're trying to make sure we put all that information out there, we're connected with the NASA NEA Scout Solar Cell Mission launching in a year or two. Uh, we're trying to learn as much as we can before our spacecraft actually meets its fiery end, it's, uh, atmospheric drag pulls it back into the atmosphere, but that's at least months away.

Matt Kaplan: Months away. Okay. Thank you for that. Excellent, eh, excellent update. What's up?

Bruce Betts: What's up is, um, I mean I always talk planets, but we've got all five naked eye visible planets, uh, not counting [inaudible 00:42:50], which is challenging to see, but technically is up as well. Anyway, they're all up right now in the evening West, you've got super bright Venus dominating in West countenance [00:43:00] that for a few days, week or two, you might catch Mercury if you can get a clear view to the Western horizon, looking below it. The morning, as I keep advertising, is just becoming a planet parties. So if you look in the East, going from highest to lowest, Mars is in the upper right looking reddish, brighter Jupiter is below it to the lower left. Saturn is still pretty low, but you can catch it if you've got a horizon view looking yellowish, and the moon will be visiting each of them, uh, in the coming a few days. So on the 18th, it'll be hanging out very close to Mars, on the 19th, close to Jupiter, on the 20th, close to Saturn. So go, uh, if you're a predawn person, check out the East on the 18th, 19th and 20th, you'll see some pretty views.

Matt Kaplan: Lots to see.

Bruce Betts: We'll move on to this weekend space history. And it was a, an eclectic week, uh, all sorts of different stuff going all the way back to [00:44:00] 1930. Pluto was discovered. We're rapidly coming forward to 1990, uh, Voyager, uh, one Spacecraft took the pale blue dot image, the solar system portrait. And 10 years later, Shoemaker NEAR, NEAR Shoemaker spacecraft, uh, started orbiting the asteroid arrows, and one year later, an orbiter landed successfully on an asteroid, which I still think is an amazing, uh, feat. And 2013, let us not forget, asteroids hit the earth. Chelyabinsk uh, w- had a Astro 18 meter asteroid, uh, hit and disrupt in the sky and uh, injure over a thousand people. So it, a little reminder. Planetary defense is important. Go to to learn more.

Matt Kaplan: Something, we're... sorry I didn't stop my email and so it just beeped in my ear, [00:45:00] uh, but probably none in years and now I've closed that. Okay. Got it. Something, um, something that we're very interested in at the Planetary Society, helping to, uh, preserve our world, I... boy, not just a lot up in the sky, but a lot to, a lot to look back on as well. Quite a week.

Bruce Betts: Indeed. Speaking of looking... okay, really not speaking, [inaudible 00:45:25]. We move on to, [inaudible 00:45:27].

Matt Kaplan: [laughing], I don't know how to describe that.

Bruce Betts: That was the goal. So uh, NASA Astronaut, Christina Koch, just returned from Space, uh, as was put out in the press. She holds the record for the longest single space flight by a woman at 328 days. That places her seventh overall and say-

Matt Kaplan: Hey, wait. I better stop you. I just realized, I think it's Koch, cause I had to look it up [crosstalk 00:45:57]. Yeah.

Bruce Betts: I wondered as I was saying [00:46:00] that cause you don't want to upset [crosstalk 00:46:02].

Matt Kaplan: Yeah, well, you were doing great, just do that again, but-

Bruce Betts: Yeah, it's Koch? That sounds [crosstalk 00:46:06].

Matt Kaplan: Yeah.

Bruce Betts: Thank you. Thank you for saving-

Matt Kaplan: Sure, sure.

Bruce Betts: All right. I'll pick up after our witty banter.

Matt Kaplan: Mm-hmm [affirmative].

Bruce Betts: So NASA astronaut, Christina Koch just returned from Space from the International Space Station where she set the record for the longest single space flight by a woman at 328 days, that places her seventh overall for longest single space flight and second for Americans behind Scott Kelly. The other five ahead of her were Soviet or Russian depending on the timeframe.

Matt Kaplan: You know, I'd been wondering about that. I knew about Scott Kelly but I was pretty sure it was some of those Soviet slash Russian uh, folks who uh, who were still leading the pack.

Bruce Betts: They are indeed. In fact, top couple were actually setting their records on board NEAR rather than International [00:47:00] Space Station.

Matt Kaplan: Interesting. Wow.

Bruce Betts: We move on to the trivia contest and I asked you, of the planets, M dwarf planets in our solar system, which has the shortest day, to be more specific, solar day. How'd we do Matt?

Matt Kaplan: Uh, you folks out there, you made this one difficult because there were so many clever comments about this question and so many of you who said you are entering for the first time, and some of them, some of them had just discovered the uh, the show. So uh, welcome, first of all, to all of you, I wish we had time to read all the clever stuff, but let's start with the, the winner. And that was Ryan Sexton in Preston, Minnesota or am I getting ahead of myself? He believes it's [inaudible 00:47:44], that has the shortest day, about 3.9 earth hours.

Bruce Betts: That is correct. It's a spinning little bugger. That's the technic- technical term for it.

Matt Kaplan: Well, Ryan, congrats. Uh, he also says, "First time [00:48:00] trivia player and just recently discovered your podcast, and best of all, joined the Planetary Society. Thanks for all you do." [laughs]. Thank you Ryan. We're gonna send Ryan a copy of Keith Cooper's new book, the Contact Paradox, challenging our assumptions in the search for extraterrestrial intelligence, along with the Planetary Radio t-shirt from the Planetary Society store at

John Brulee, "Takes 283 years for [inaudible 00:48:33], to orbit our star." He says, "I guess that means a year on [inaudible 00:48:38], has 635,661.5 days. [laughs].

Bruce Betts: [laughs]. Wow, that's a lot.

Matt Kaplan: We had a lot of rifts on that. Robert Cobain in Massachusetts, he said "The, the -402 degree Fahrenheit doesn't sound like fun, but I like the idea of a 78 minute Workday. [laughs].

Bruce Betts: [laughs].

Matt Kaplan: [00:49:00] He said even on [inaudible 00:49:02], equivalent to Monday, you're only 19 and a half hours from the weekend. [laughs].

Bruce Betts: [laughs].

Matt Kaplan: E- Elliot Popo in California. He looked at it differently. He said, "I should get a promotion. I usually stay at work for two [inaudible 00:49:16], days at a time before going home."

Bruce Betts: Wow. That's dedication. Wait a second.

Matt Kaplan: [laughing], not really. Not so much. Ola Franzen, one of our Swedish listeners, "It's amazing how physics can work so differently, turning a dwarf planet into an ellipsoid from spinning so fast, while at the same time, also turning my midsection into an ellipsoid from lying still in bed with a broken leg." [laughs].

Bruce Betts: [laughs]. [inaudible 00:49:47], it's amazing.

Matt Kaplan: We're laughing with you, Ola, not, not at you. I promise. I love this one. Darren Richie will close this out. He's from Washington, the state, not the Capitol, "Honorable mention to [00:50:00] Washington D.C. whose rate of spin is so fast as to be unmeasurable. However, it does not meet the IU's definition of a dwarf planet having failed to achieve equilibrium of any sort." [laughs].

Bruce Betts: [laughs].

Matt Kaplan: Well done, Daron.

Bruce Betts: All right, question out of human space flight. Who performed the longest solo space flight? That's it. Go to

Matt Kaplan: Clearly we're looking back toward the beginning of human space flight for this one. Uh, you have-

Bruce Betts: Stop giving them clues.

Matt Kaplan: [laughs]. You have until the 19th. That'd be February 19 at 8:00 AM Pacific Time to answer this one, and if you lucky enough to win, we haven't given one away in ages, how about a Planetary Society rubber asteroid and-

Bruce Betts: Ooh.

Matt Kaplan: I know, and a Planetary Radio [00:51:00] tee shirt from

Bruce Betts: All right, everybody, go out there, look up the night sky and think about if you had a really tall cherry picker, you know one of those devices that lifts you up high, what fun thing would you do with it?

Matt Kaplan: [laughs].

Bruce Betts: Think, uh... sorry, I got myself all excited with the [inaudible 00:51:20].

Matt Kaplan: [laughs]. I, I hesitate to speculate. I... are you looking out your window at the construction project across the street?

Bruce Betts: No, I'm supposed to sound so random, but yes, there's a giant cherry figure. They're like lifting the guy up to the third floor of a building. It's very exciting. So I'm sorry it wasn't random, but it did, it was a legitimate thought.

Matt Kaplan: I would just like to be that much closer to everything that's what's up above our heads. [laughs].

Bruce Betts: [laughs].

Matt Kaplan: But it's, it's Bruce, the chief scientist of the Planetary Society who gets us a little bit closer each week [00:52:00] as he joins us for What's Up. Planetary radio is produced by the Planetary Society in Pasadena, California, and is made possible by its worldly members. You can become a hero of the solar system by joining them at Mark Hilverda is our associate producer, Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. Please leave us a rating or review in iTunes and elsewhere. Ad astra, everybody.