Planetary Radio • Mar 31, 2021

NASA’s TESS Exoplanet Mission Finds Over 2,000 Possible New Worlds

Please accept marketing-cookies to listen to this podcast.

Download MP3

On This Episode

Natalia guerrero portrait

Natalia Guerrero

TESS Objects of Interest (TOI) manager and MIT-TESS communications lead

Bruce betts portrait hq library

Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

Kaplan mat headshot 0114a print

Mat Kaplan

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

The Transiting Exoplanet Survey Satellite (TESS) team has just announced more than 2,200 new exoplanet candidates. Natalia Guerrero of the Massachusetts Institute of Technology manages these discoveries and still finds time to write plays, collaborate on musical performances and host radio shows that dig into the deeper meaning of our expanding universe. The Venusian phosphine debate continues! Space journalist Nancy Atkinson provides an update. Bruce Betts returns to expand our knowledge of the night sky and present a new space trivia contest in What’s Up.

Natalia Guerrero at launch pad for TESS
Natalia Guerrero at launch pad for TESS Image: Michelle Gabutti
TESS two-year target observation map
TESS two-year target observation map Each point in this map represents a target observed at two-minute cadence. The color of the dot represents the number of times it was observed. The U-shaped red curve shows the galactic plane, with the position of the galactic center shown by the red star. Over the course of its two-year primary mission, TESS observed 26 sectors for approximately 27 days each, covering ∼ 70% of the sky. Each sector is a 24◦ × 96◦ field of view.Image: MIT
TESS imaging process
TESS imaging process Image: NASA

Related Links

Trivia Contest

This week's prize:

A copy of The Backyard Astronomer’s Field Guide: How to Find the Best Objects the Night Sky has to Offer by David Dickinson

This week's question:

Name all the people who flew in space while serving in the U.S. Congress.

To submit your answer:

Complete the contest entry form at or write to us at [email protected] no later than Wednesday, April 7th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

What part of the International Space Station is named after a chess piece?


The winner will be revealed next week.

Question from the 17 March 2021 space trivia contest:

What was the Hayabusa2’s Small Carry-on Impactor’s (SCI’s) projectile made of?


The Hayabusa2 Small Carry-on Impactor’s projectile was made of copper.


Mat Kaplan: 2200 new worlds and a song inspired by them, this week on Planetary Radio. Welcome, I'm Mat Kaplan, of the Planetary Society. With more of the human adventure across our solar system and beyond, someone has to keep track of the thousands of exoplanets discovered by TESS, the Transiting Exoplanet Survey Satellite, that person is Natalia Guerrero. Natalia's lead author of the brand new paper announcing those new worlds. She'll talk to us about this great science and also about how it inspires much of her dramatic musical and radio artistry.

Mat Kaplan: We're also going to check in with Nancy Atkinson in moments, Nancy is tracking the tail of that Venusian Phosphine, new yet very old data backs its existence. I also have an especially good time with Bruce Betts this week. So I hope you'll stay for What's Up. As always, we're grateful to all of you who listen, grateful to those who write to us, and extraordinarily grateful to everyone who leaves us a rating or review in Apple podcasts.

Mat Kaplan: I hope you'll consider helping us out this way if you haven't. I don't know if it's a moonrise or a moonset, either way it's like none I've ever seen. It's that Martian moon Phobos peaking through the clouds above Mount Sharp in a photo snapped by the Curiosity Rover. You'll find it at where it is followed by these headlines and much more. As some expected, the Biden administration has nominated former Florida Senator Bill Nelson to take on the job of NASA Administrator.

Mat Kaplan: Nelson flew on the space shuttle when he was still in office back in 1986. The next step is confirmation by his old congressional body. Ingenuity is several steps closer to take off, by the time you read this, the Mars helicopter may have been dropped off by Perseverance up there in jazz a row crater. We may be just days from the first flight by a rotorcraft on the red planet, or anywhere else other than earth. By the way, some of you notice that I forgot last week to post a link to the virtual video drive around a Martian outcrop assembled by Mathias Murmur.

Mat Kaplan: It's still highly recommended and you'll find it on this week's episode page at Veteran space journalist and author Nancy Atkinson writes for Universe Today, Ad Astra, and The Planetary Society. She panned the lead article in the new March Equinox edition of the Planetary Report. The society's magazine that is available free to all at, where our members get the printed version.

Mat Kaplan: Her piece is titled, The Quest for Life on Venus: Is Something Alive on the Planet Next Door? This would have been reason enough to bring Nancy back to Planetary Radio, but now there's even more of Venusian news. Nancy, back to the show. I think I had only just finished your great piece in the planetary report. When this update had to come out on our website, March 25th, article titled, NASA Mission to Venus in 1978 May Have Detected Phosphine a Gas Related to Life. Man, this story just keeps evolving. Doesn't it?

Nancy Atkinson: It really does. There's just a lot to this story and it's really been fun to watch the science play out, and just see how everyone is tackling this, and looking at the data, and giving it a go.

Mat Kaplan: Well, we will make both of these articles available of course, the digital version of the Planetary Report. It's the March Equinox issue, our edition that is available on our website, but also we'll have a link on this week show page at to this March 25th update article. It's a recurring theme of course, how ancient, if I can be so bold, data once again, is proving useful in very current cutting edge science.

Nancy Atkinson: Right. I think there really is something endearing about these old planetary missions because they tried and accomplish some pretty audacious things. The fact that old data from the Pioneer Venus Multiprobe was robust enough, where it could be mined to look for chemicals or elements that really wasn't designed to look for. That's just something really special. So hats off to Rakesh Mogul, and his team at Cal Poly Pomona for doing just that.

Mat Kaplan: Give us an idea of what Rakesh and his team had to do to get at this data to make it useful again.

Nancy Atkinson: Well, he was telling me that at first, all they had was some tables in a few old publications. Later on NASA released some additional archival data to take a look at, but there really wasn't a lot of contextual information that they had to go on. Originally this instrument, this mission sent down several probes down into the atmosphere of Venus. And this probe was the largest one and it went down on a parachute through the atmosphere.

Nancy Atkinson: Originally the team was just looking for kind of common things like water or carbon dioxide. For them to mine the data, and just kind of see what Rakesh Mogul told me, was the data within the data. And what they found was like a phosphorus base chemical. Phosphene is what fits it, it fits the data the best. That's why they're kind of confirming what Jean Greaves and her team found.

Mat Kaplan: And as you know, we've talked to Jane Greaves a couple of times last year, when her findings were first published, and then her answer to some of the criticism that was coming in. And people can read more about that in your article in the Planetary Report, of course. We're still not talking yet about proof that the phosphene is there, right? Much less proof that life is creating it.

Nancy Atkinson: No, I think this story is ongoing. Really what it's going to take is a mission to Venus, another new mission. I talked to so many people in the planetary science community, and almost everyone is saying we really need a new mission to Venus. I talked to David Grinspoon from the Planetary Science Institute, and he said, there are 1,001 reasons that we should go to Venus with a new mission. And even if there's not, phosphene, there's still a thousand reasons.

Mat Kaplan: Well, your coverage hopefully is going to help that case Nancy, it has made quite a splash almost off the charts. Sure indicates that at least the people who pay attention to Planetary Society Channels, care a lot about that second rock from the sun.

Nancy Atkinson: Yes, and the phosphene story it was a bright spot in a year that wasn't so bright. Between the phosphene story and now the old data from the old Venus mission, I just think that makes for a great story.

Mat Kaplan: Thank you Nancy. Really appreciate it, and hope to be talking again soon.

Nancy Atkinson: Thanks a lot, Mat.

Mat Kaplan: Space journalist, Nancy Atkinson. We haven't checked in with TESS for a while. The Transiting Exoplanet Survey Satellite is well into its extended mission. Another two years of scanning the Milky Way, for worlds circling other stars. Natalia Guerrero works with TESS at the Massachusetts Institute of Technology, the lead institution for this brilliantly successful mission. Natalia's the TESS Objects of Interest or TOI manager, and the communications lead for TESS at MIT.

Mat Kaplan: As you'll hear my interview with her was already lined up when the team dropped us science bombshell, I didn't know it was coming. That's just one factor that makes the conversation you're about to hear so interesting. Add to it, Natalia's other life as a playwright artist and radio host, all of which we talked about a few days ago. Welcome to planetary radio and congratulations on the publication of this terrific paper, which I'm sure we're going to be spending some time talking about.

Natalia Guerrero: Thank you very much, and thank you for having me.

Mat Kaplan: You know when we set this interview up, you didn't mention that you were going to be the lead author of a paper coming out, actually, as we speak just about 24 hours ago, it really is an amazing publication. And so I have to say again, congratulations.

Natalia Guerrero: Thank you. The title page went on the refrigerator right away last night.

Mat Kaplan: That's great, at your mom's house?

Natalia Guerrero: Yeah.

Mat Kaplan: Because I know that's where you're talking to us from. Oh, she has a right to be very proud. More than 2200 candidates to add to those that were discovered previously by Kepler and other techniques, absolutely amazing crop of new exoplanets or at least candidates exoplanets. How many of these appear to maybe be somewhat similar to the one that we live on?

Natalia Guerrero: That's a good questions. When TESS began, we predicted that we would find several hundred planets that would be smaller than about Neptune size. Four times the size of earth, and so far so good, we are definitely finding planets in that regime. And now the trick is to within that set, look for planets that are interesting to astronomers for different reasons. Of course, everyone's interested in habitable zone exoplanets, but there's also hot Jupiters, and different other types of planets that look nothing like the ones in our solar system. And that's also very exciting to study.

Mat Kaplan: Well, you can't blame us for having a sort of biased interest in the worlds that look like our own. But yeah, every one of these worlds is a terrific fine. I read that you think of this as sort of a to-do list. What do you mean by that?

Natalia Guerrero: At the risk of stressing everybody out, I really do think that the TY catalog, or beautiful way to look at it is as a list of things to go after and explore. Each object has its own story, and even the targets that end up being false positives, that's a little detective novel, each one of them. I think, as we keep adding targets to this list, it means a new object for someone in the followup community to go after, and observe with a ground-based telescope.

Natalia Guerrero: It means many more years hopefully, of observation with ground-based and space-based telescopes. We hope that each one of these planets has its own story, the other way I like to think of it is, I am always a machine of creating more work for not only myself, but other people. Hopefully this leads to a lot of good interesting work.

Mat Kaplan: With all those giant new earth-based telescopes coming online before too long, and fingers crossed, James Webb Space Telescope that I've been talking for years with your colleagues, Sarah Seager, who's second author on the paper and others about. We're all hoping it's going to one fold just fine late this year, and start poking around. Do you have hope that we're going to be able to do these follow-up observations at a new much deeper level, and maybe learn something about the atmospheres of some of these worlds?

Natalia Guerrero: Definitely. I am so excited both for the ground-based and space-based telescopes that are coming in the next decade, because the cycle of that happens of as TESS and other survey missions find candidates that are good for atmospheric followup and characterization. We are also able to say, "Hey, we need telescopes that can follow these up." And as we get more information from James Webb, and other ground-based telescopes that can look into the chemical fingerprint of these planets atmospheres, we can say, we found this information now, let's go find more planets that look like this, or don't look like this.

Mat Kaplan: Our audience has been hearing about the search for exoplanets really from the beginning of this show more than 18 years ago. But I think it would probably be a good idea to remind us of how TESS makes these discoveries. It does it very much in the way that that Kepler Spacecraft, that wonderful pioneer, doesn't it?

Natalia Guerrero: Yes, that's right. TESS uses what Kepler used the same measurement method called the transit method. In which essentially a planet is aligned in its orbit and around its star from our point of view, such that as it's going around its host star, it blocks out a tiny fraction of that stars light. And TESS can detect up to about a 1% reduction in the light from that star. So we're not actually seeing the plant directly, but we are able to see this little blip in the amount of light that we're measuring from this star.

Mat Kaplan: So Kepler stared for a long time at one relatively small section of the sky. How does TESS improve on that?

Natalia Guerrero: TESS is nearly all sky survey, in the first two years of operation from summer 2018 to just last summer, summer 2020. TESS observed about 70% of the night sky, and so that was covering these overlapping long rectangular strips of the sky called Sectors. And it stared at each one of those for a month. We have a time-lapse movie basically of those sections of the sky for a month. And now we're in our extended mission, which means that we are re-observing the Southern Hemisphere, the sky visible from Australia, South America, and we're able to re-observe that area of the sky, cover up the little gaps between the sectors that we missed the first time.

Natalia Guerrero: And when we go to the north later this summer, we're going to be able to observe part of the Northern Hemisphere, as well as a part of the sky that TESS has never observed before. We're going to be observing the ecliptic plane, basically the area of the sky that we weren't able to cover in the first part of the primary mission. And this is exciting because this overlaps actually with Kepler, with the K2 mission, which observed several campaigns in the ecliptic. So this will be really exciting for astronomers who have favorite planets in those areas.

Mat Kaplan: When you talk about the ecliptic in this case, we're talking about right along what the plane of the Milky Way Galaxy, and the ecliptic of our solar system as well, where you would expect to see a lot more planets, because there are a lot more stars.

Natalia Guerrero: Yes, that's right.

Mat Kaplan: Those areas which TESS has already looked at before, have stared at for a month, you'll be repeating some of that. What is the value in that?

Natalia Guerrero: Each of the sectors overlaps at the Southern and Northern ecliptic pole? So we get almost an entire year of observations at those poles, which is the TESS continuous viewing zone. That's already able to give us multiple transits of planets that have periods where they're transiting multiple times in that year, but when we come back to them, and the second time in the extended mission, we're able to see are these planets changing in how they're orbiting?

Natalia Guerrero: Does this reveal additional, "Hidden planets?" There's something called Transit Timing Variations, where additional planets in the system can cause delays, or differences so that the planet isn't orbiting at exactly its period each time. These are really interesting additional pieces of information that we're able to get with a longer baseline of data.

Mat Kaplan: Complex stuff. I mean, multiple planets working with a star and in some cases, a fairly small star makes me think of that classic problem known as the three body problem, and trying to figure all this stuff. It's amazing that it can be done just from looking at the demean light from these distance stuff.

Natalia Guerrero: It's really amazing to see how much, I guess, the scientific imagination builds up this picture, that all of these things are measurements, the mass of a planet, the period, how often it transits, but using all of those numbers, we can build for ourselves a picture of what this planet may look like. And one day we may be able to actually directly image a planet, but until then, this is what we're working with.

Mat Kaplan: Fingers crossed. I love that phrase, scientific imagination. I think we're going to come back later in this conversation to the topic of imagination, and that intersection of science and art that I know is also something that you love. We're certainly not going to be able to talk about more than two or three of these 2200 candidates worlds, but I hope you can introduce us to some of them. Do you have any that jump up to the top of your list that you might want to talk about?

Natalia Guerrero: Sure. One that I was looking at recently was in the last couple of months, we've gotten a few planets that were initially discovered by TESS, that have gotten additional follow-up by the CHEOPS Mission. And CHEOPS is another space telescope, it's about the same size as TESS, which I find amusing. We often describe TESS as being about the size of a refrigerator. And CHEOPS is also another refrigerator in space looking for exoplanets.

Natalia Guerrero: And so with CHEOPS, we were able to follow up this planet. The set of planet candidates called TOI-178. This ended up being a six planets system, which was really interesting. And we alerted the first three planets from this system back in the second sector of test data. So two months after we really started taking science data, then CHEOPS went and stared at Justice System in a very focused way, and was able to get much higher detail information because that's the only system it was looking at, it looked at it for 11 days straight.

Natalia Guerrero: From that, they were able to pick out that there are actually six planets in this system, three that TESS found initially and an additional three. And they're calling this a Trojan System because it sort of has the same resonance pattern as the moons of Jupiter.

Mat Kaplan: Fascinating. And we should give credit to CHEOPS, which is a spacecraft put up there by the European space agency. But it's great to hear how TESS and CHEOPS can compliment each other.

Natalia Guerrero: Definitely. It's really wonderful to have a dialogue between this mission and our own.

Mat Kaplan: Any other worlds that you... Let me suggest one you TOI-700D.

Natalia Guerrero: I was wondering if you were going to bring that one up, because you touched on it before it looks like.

Mat Kaplan: I'm partial to those are sized worlds in their Goldilocks zone.

Natalia Guerrero: Definitely. So that was another really exciting system. And I found it an amazing discovery, not only because it was the first habitable zone exoplanet that TESS found, but also because out of the three papers that came out on the system, two of them were led by junior scientists. One was a grad student, one was a student who wasn't even in grad school when she began this paper. And that was exciting because it just shows that this is such a new field and there's so much work to do. We really want to welcome and bring all hands on deck for it.

Mat Kaplan: Love it when we hear about a young researchers, at the beginnings of their careers who are at the forefront of what becomes great published work. There's one more of these I want to bring up, an article that I found about your paper described it as an extremely rare oddity, and that's TOI-849B. Enormous dense remnant core of a gas giant, and the one that it's atmosphere may have been stripped away, 40 times the mass of earth, but only three times the diameter.

Natalia Guerrero: TOI-849B is really interesting, because it's an interesting combination of the mass and radius of a planet. TESS is really wonderful because it's giving us all of these candidate exoplanets that we can go and with other ground-based telescopes measure their mass. Once you have the mass of an exoplanet, you can start asking interesting questions like, this planet is very small, but very massive, why is that? Or this planet is really big, but really fluffy, why is that? This planet occupies an interesting area because it is really hot, and it's also Neptune.

Natalia Guerrero: There aren't very many of those that have been discovered to date. And so we're trying to understand, is that because those just don't form, or those just don't evolve that way, or is this something that we're just not able to detect them for whatever reason? I always find it interesting to see those little spaces in our comparisons of mass and radius, or period and radius and see where are we filling things in, or what's left to discover, what's not there?

Mat Kaplan: I used the description from this article that called TOI-849B an extremely rare oddity. It took me a few minutes before the real import of that statement hit me. And it's this, that we've gone in a handful of decades from Michelle Myers discovery of the first exoplanet, to knowing about so many now that we can recognize one as especially rare or weird, that's progress in my book.

Natalia Guerrero: Exactly. It's this luxury of having thousands of planets to compare to each other.

Mat Kaplan: If I counted anywhere near correctly, there were over 100 scientists listed as your co-authors. It's a real who's who of exoplanet research. Do you want to say something about this global team?

Natalia Guerrero: Yes. The TESS collaboration is enormous. And part of that is because the data leaves so much room for possibility. And so we have folks at MIT, and Harvard who are working on leading the effort on downlinking, and analyzing the data, and also coordinating the follow-up observations from the ground. We work with various NASA partners for data analysis and planning observations, and also working with guest investigators.

Natalia Guerrero: And so it's this huge team and it's international, and so actually one of the things that we were worried about was when the pandemic started to peak last spring was okay, what is this going to do for tests? And what is this going to do for exoplanets in general? And so although a lot of observatories did end up having to shut down or reduce their staff, and so we slowed down on the follow-up. We were able to continue analyzing and creating TOIs, because so many of us are already scattered across several times zones that going to fully remote was a lot easier transition than I would have expected initially.

Mat Kaplan: What's ahead? I mean, you're willing to the extended mission, but you got a ways to go. I assume that TESS is in good health, and still doing a great job of staring at the stars. What is still to come?

Natalia Guerrero: Yes, TESS is doing great. We're really excited for the fourth year of TESS operation. I mentioned before that we're going to be observing the ecliptic plane. But after that TESS is really stable and it hardly uses any fuel. It's possible that TESS can continue observing for decades to come and keep building up this time-lapse, this movie of what's going on across the sky over a period of many years.

Natalia Guerrero: And maybe that'll even give us information about planets that we only have seen transit their star once. And maybe they have a many 100s day transiting period. And in a couple of years, we'll catch another transit, and we'll be able to constrain that period. That's what I'm really excited about, is finding these far out planets that we can hopefully detect later on with TESS.

Mat Kaplan: Nice to know that we have a lot to look forward to. More from Natalia Guerrero is coming up, including samples of her musical, and theatrical work.

Casey Dreier: Space exploration doesn't just happen, in a democracy where you're competing against other priorities and resources. We need to maintain a constant engagement in the political process to ensure the types of missions we want to see in the future. I'm Casey Dryer, I'm the Chief Advocate here at The Planetary Society. I'm asking you to consider making a donation to our program of Space Policy and Advocacy that works every single day to promote your values in space science and exploration to the people who make the decisions in our democracy. Your donations keep us independent, keep us engaged, and keep us effective. Go to That's Thank you.

Mat Kaplan: Now I mentioned that beautiful map, which we will put on this week show page at, that shows where TESS has looked across the sky already. To me that's art. It's a thing of beauty. I said that we needed to talk about this intersection of art and science. It's something that I think you're pretty fond of.

Natalia Guerrero: Yes, definitely. I am always really interested in the dialogue between art and astronomy. Often I'll find myself thinking about technical problem in astronomy, and my mind will immediately start making metaphors as a way to explain it, not only to myself, but to others and say like, "Would this be a good metaphor? Would this be a good way to think about this?" That's in one direction, and then the other direction trying to bring new ways of thinking about astronomy to astronomers. So that's what I'm really interested in as well, is trying to reframe what we're doing, such that we can maybe make new connections or new insights that we wouldn't have been able to if we're just looking at the data, doing analysis.

Mat Kaplan: I hear this kind of thing from so many scientists, but very few of them who have their hands in as many artistic media as you do. And I want to talk a little bit about this, maybe start with telling us something about this group of playwrights called Catalyze.

Natalia Guerrero: Yes, MIT has this really unique partnership with the Central Square Theater, which is just a 10 minute walk from our campus. There's this collaboration of scientists and theater makers of various sorts called Catalyst. A few years ago, some friends and I put together a sort of satellite group called the Catalyst Collective. And so what we do is we try and work on plays and work with each other. Many of us are MIT alumni, and have a strong technical background, but also really loves theater.

Natalia Guerrero: The group has gone on to continue to produce readings, and short plays, often going related thematically to what the theater is putting on that season. But it's this really interesting thing where all of these works of theater have come out of this collaborative, both in the one I'm involved with, and more broadly that make feeder that is about the history of science, and physics, problems of the future, and sort of speculate as well on what current discoveries are going to bring.

Mat Kaplan: To get more specific, I read about and even got a little sample of something called the Drake Equation Plays based of course, on the famous Drake Equation. Frank Drake, one of my heroes, a past guest on this program. And you contributed something to it called the Megahertz Express, which is pretty entertaining. Can you say something about that? And then I'm hoping that we can maybe share a very short excerpt from Megahertz Express.

Natalia Guerrero: Yes. This was a short play that I wrote as part of this Drake equation series, where I wanted to play around with this idea of which wavelengths are we searching on for signs of life. And I chose megahertz, because that's where you're getting into the radio. And that's where it's savvy, that's their playground. Thinking about how would different civilizations at different periods in time of their evolution be talking to each other. And I ride the MBTA train to work every day.

Natalia Guerrero: And so I thought, will this be interesting, if this took place on a train? These people having these conversations that talk about sort of intermingling of civilizations, and those are the last few terms on the Drake equation, the likelihood of interacting.

Mat Kaplan: Here is just a very short sample, a really short clip from megahertz express. Natalia Guerrero's little play that she has just been talking to you about. This was done as part of a an onstage dramatic reading.

Natalia Guerrero: Yes, that's right.

Speaker 5: I have some new images [inaudible 00:30:00] of where we live, what it looks like, how to file this, or this rover.

Speaker 6: It's small, and it can go super far.

Speaker 5: Oh, I got it, it's awesome.

Speaker 7: Guys.

Speaker 6: Oh, hey, there. This is a space ship.

Speaker 5: Oh, that's incredible. Here, let's race them, three, set, go.

Speaker 8: The enthusiasm of the first exchange of commonality.

Speaker 7: Yeah, this is our first time on this frequency officer.

Speaker 6: Officers whose [inaudible 00:30:34] provide more record.

Speaker 5: Would you like a recording?

Speaker 7: Sure. I don't have anything new in school, just some data for [inaudible 00:30:46].

Speaker 5: Do you see [inaudible 00:30:46] next.

Speaker 8: It is contemplation of another world.

Speaker 6: They just gave it to me. Let me see if I have another in my bag. We've been floating around for years. We have seen so many young planets each different in their own way.

Speaker 7: Brilliant, [inaudible 00:31:10]?

Speaker 6: Yes. Observing from afar, choosing with whom we share our stories. We find that has been the most successful technique.

Mat Kaplan: There was just a very short clip from Megahertz Express from our guests today, Natalia Guerrero. That's not all you do, you've gotten involved with music as well. Tell us a little bit about songs from extra solar spaces. Then we'll tell people how later in the program, they're going to be able to hear one particular short song titled, Gee Who Could Have Guessed Exoplanets.

Natalia Guerrero: Yes. Songs for Extra Solar Spaces was a concert that I wanted to create to celebrate the first year of TESS's discoveries. Not only to communicate the magnitude of these discoveries to the public, but also to invite astronomers who were attending the TESS Science Conference that summer to come in and reflect on what it means to make these discoveries, and hopefully spark some new connections, make some new ideas happen.

Natalia Guerrero: And so I worked with a composer at MIT, Alaina Roar. She and I talked about the text. I put together a text for her, which was a foreign text from a bunch of papers that had come out in that first year from TESS. So all of the texts is pulled from titles of papers, and I arranged them in a way that she could work with. And I love writing librettos, I minored in writing as undergraduate, and this was really exciting for me to participate in that way.

Natalia Guerrero: And she composed this piece of music and we also put together a program of other pieces that were related to discovery and to space. And so she wrote two, and then we pulled a piece from John Harvison, another from Meredith Monk. We also had a piece from Molly Heron about various facets of astronomy and discovery. With these pieces, we had them performed by a vocal ensemble, the Lorelei Ensemble, who had actually matched through my radio show Voicebox a few years prior.

Natalia Guerrero: That was the vocal element, but I also wanted a visual element. And so I worked on a piece of video art that was a composite of frames from the TESS images, showing the changes in light exaggerated of the stars going from observation to observation. And I merged those with little videos of reflections and optical effects that my mom had taken. She's a video artist, and so it was this multimedia collaboration, and using a lot of different connections. And I brought this together on the stage at MIT for this audience. And it was this really special event where all of these different people from all of these different backgrounds could sit and watch and experience this distilled TESS results in this space.

Mat Kaplan: I wish I had been there. On the audience, many people out there regulars know that I love this stuff. This has all been an elaborate tease basically, because we're not going to play that a song called, Exoplanets until the end of the today's episode. So you got to wait and go through what's up with Bruce, and then we will close the show with it. At least for you podcast listeners, anybody listening to it on the radio, you're only going to be able to get a little piece of it, but you can go to this weeks show at and hear the whole tune.

Mat Kaplan: I love that some of this came out of the fact that you have or had, is it a radio show? Because it's really sounds like as I looked at what you're up to. That you love to do the same kind of radio that I love to do. I mean, periodically we do Planetary Radio live, and I love putting performers on stage as a part of that, as we talk to scientists, does that sound like the kind of thing that you've tried to achieve?

Natalia Guerrero: It does. My background in radio is at MIT's College Radio Station, WNBR. I started actually as an undergraduate with an idea for a radio play called Girl in Space, which was actually about two rival missions going through sort of process of are we really going to land on an exoplanet, and some of the anthropological, and cultural ethical questions behind that? From there I was hooked, I love the idea of performing live music, live theater on the radio.

Natalia Guerrero: And so my first show was called Charles River variety, and it was a live music sketch comedy variety show. Musicians from Berkeley College of Music and the Cayden Bridge area, as well as sketches that I wrote with myself and a team of friends. And from there, I noticed that I really loved vocal music, and this was something that I wanted to sort of explore further. That show evolved into the show that I had until about 2018, called Voicebox. And Voicebox was this deep dive on vocal music in all of its forms. So opera, acapella, everything.

Natalia Guerrero: With that, I was also trying to work in science themes, and so sometimes I would bring colleagues on. In fact, I had a fellow astronomer, Sarah Ballard come on one evening and she brought a playlist of songs that had been playing at instrumental points in her career. Like when she finished her thesis, when she discovered her first exoplanet, and she also plays guitar. And so I asked her to play guitar for me on the show. And it was this interesting portrait, again, of an astronomer who has these interests.

Mat Kaplan: There is nothing as exciting as live in front of an audience. Is there?

Natalia Guerrero: No, I really love it.

Mat Kaplan: You and me both, Natalia, what's ahead for you? We know TESS is going to keep doing its work, and I assume you will continue to lead, to manage that a team that deals with the objects of interest, but what else is happening with you? I noted in your bio that you used to be maybe still are involved with the attempt to understand that crazy stuff called Dark Matter.

Natalia Guerrero: That's right. Yes, I have a background in particle physics, and Dark Matter research from my undergraduate years. And I'm always looking for new ways to incorporate Dark Matter discovery and that detection into what I do now. And so I'm broadly interested in new missions that will allow us to look for these sorts of signatures. I'm also interested in continuing to work as an artist/astronomer. I'm continuing to work on plays that explore these sort of human themes and scientific themes. And so that's something that I'm actually really interested in doing.

Natalia Guerrero: This past spring, you mentioned the test image before of the full sky, what we've covered. And I was able to advise a high school student who was a graphic design student, or interested in design, but wanting to also understand science. And so we work together on a visualization of all of the TESS objects of interest on this night sky. And that student Grady [inaudible 00:38:39] is now doing his undergraduate in design. And so I'm very proud of him. And this lit a fire in me to say, "I really love this work of helping people think about both things at the same time, art and astronomy." So I'd like to be able to have opportunities in the future to continue to do that.

Mat Kaplan: Please keep that up, even as you continue to lead this team that is discovering all these new worlds, literally new worlds across our galaxy exciting stuff. I'd love to do some live radio with you someday Natalia.

Natalia Guerrero: Let's do it.

Mat Kaplan: Let's look at that opportunity. Yeah, let's go for it. Thank you so much, and congratulations once again, not just to you, but to the entire TESS team. Keep up the great work and we look forward to following not just TESS's his career, but yours as well. I hope we'll talk again.

Natalia Guerrero: Thanks for having me on.

Mat Kaplan: MIT's Natalia Guerrero. I'll be right back with Bruce and What's Up. Time for What's Up on Planetary Radio. The Chief Scientist of the Planetary Society joins us once again to tell us about the night sky and all the other great stuff that he brings us in this closing segment of our show. Welcome back.

Bruce Betts: Thank you, Mat. Always good to be back. It seems like we talked only a week ago.

Mat Kaplan: Yeah, I know, time flies. Congratulations by the way, I hear that you will at least soon be eligible for a vaccination. Joining us, those of us who have already completed both rounds.

Bruce Betts: Yeah, I'm very excited, very excited, never been this excited for a vaccine before, or a stick in the arm, but I'm excited.

Mat Kaplan: Glad to hear you're doing it. And I hope everybody out there listening to this is looking forward to the same if you haven't already, if you have congratulations. Congratulations on, I'm sure a gorgeous night sky too, that Bruce's going to tell us about.

Bruce Betts: It's true, it's wonderful, and does not require a pain in your arm. And so go ahead and enjoy-

Mat Kaplan: Or anywhere else.

Bruce Betts: Socially distanced, and masked, and look up in the sky, and see us or anywhere else. And check out in the evening, Southwest getting lower and lower as time is going on. Mars looking like a bright kind of bright reddish star and nearby is the reddish Aldebaran of Taurus. In the pre-dawn, we've got really bright Jupiter with a yellow or Saturn above it in the East, and that's still low, but getting higher in the sky that'll be visible for months.

Bruce Betts: You can check out the moon hanging out near them on April 6th and April 7th. We move on to this week in space history 1968, the oft forgotten Apollo Six launched this week in 1968. It was the last and crude Apollo Test Mission.

Mat Kaplan: How'd that come out?

Bruce Betts: Interesting. It came out well enough that they decided they could put humans on the next one. But they had some significant Pogo problems. I forgot the exact term Pogo oscillations in the... They had engine shut down, but they were able to compensate with other engines. So it was a good test of things not going right. And then it brought the capsule back safely with the highest speed return and the light.

Mat Kaplan: And onto bigger and better things. Here too.

Bruce Betts: All right on to [inaudible 00:42:13]. So TESS, I think our listeners have heard of that. The Transiting Exoplanet Survey Satellite, it has a fascinating orbit. It orbits earth twice during the time the moon orbits once. It's in a two to one resonance with the moon, and it gives them a unobstructed imagery of the Northern and Southern hemisphere skies but also brings in the highly elliptical orbit, brings it close to earth so they can dump large amounts of data in a short period of time. Then go up back out towards Apogee and take lots of data. But the two to one lunar resonant orbit is spiffy king.

Mat Kaplan: Horrible mechanic that I am not. And I hope you can help me with this, is the moon actually influencing TESS, or they just put it in that orbit because it had these advantages? I mean, just the moon somehow maintain that resonance?

Bruce Betts: And yes, and no. In order, I think I got your question. They put it in that orbit because it helps them do the observations that they're after, as well as doing the data transfer. I believe they use the moon for an orbital assist to change their orbit initially. But then once they reached the stable orbit, they wanted to be in, they actually go out towards moon's orbit when the moon is 90 degrees away in its orbit. Then the next time it's the opposite, 90 degrees sort of. Anyway, they tried to minimize the effects of the moon so that their orbit is nice and stable for a good 20 years or so without using much of any fuel to modify it.

Mat Kaplan: Fascinating. Thank you, that's exactly the kind of guidance I was hoping for.

Bruce Betts: I spent a lot more time preparing, because I never know what you're going to ask.

Mat Kaplan: It's good for you.

Bruce Betts: It is. I learned neat stuff like that. All right, let's go onto the trivia question unless you have another snarky comment for me.

Mat Kaplan: No, that's it for this week.

Bruce Betts: All right. I asked you what was the high booster to small carry on impactors projectile made of the SCI. What was the projectile made of? How do we do Mat?

Mat Kaplan: We had a really good response. A few people mentioned a tantalum impactor, not the one that you're looking for and they by and large knew that. But I guess, there was this other impactor, which is not the correct answer.

Bruce Betts: That is the correct answer of what is not the correct answer. Yes, how cool is the space mission that carries multiple things to shoot at an asteroid. You have the tantalum was a projectile fired from up-close where the sample collection horn that cone shaped thing would come down on the surface. Then they would fire an impact, would actually keep material into their sample mechanism.

Bruce Betts: Whereas the small carry on impactors, one I asked about is where they fired from a distance, using a ship charge, they launched a two kilometer per second projectile to create what ended up being like a 14 meter crater on the surface. So they could expose material that hadn't been sitting on the surface for a long time. And what was that projectile made up man?

Mat Kaplan: Here's the answer from funny guy, Mel Powell in California, who did his best to trip me up with this one. Takes a minute, but I think it's worth it. The small carry on impact and it's projectile, it's not a bell, so it has no clapper. It's not all that happy, so we can't call it chipper. It's not ingenuity, so it isn't a chopper. It's not bound for Europa, so it isn't a clipper. It isn't a fish, so you can't call it Kipper, not even exotic. And that is the capper. The projectile is made of just boring old copper. And now the challenge to bat for the big finish. No clapper, not chipper, not chopper, not clipper, not Kipper. The capper it's copper.

Bruce Betts: Wow, that should be a jingle for people who sell copper.

Mat Kaplan: Yeah, we should sell it to the copper consortium, I guess. He's right, right?

Bruce Betts: Yes, he is correct. Copper is indeed what was on the inside of the ship charge, which then turns it into a two kilometer per second projectile that slammed into the surface.

Mat Kaplan: We had a few people like Elijah Marshall and others who asked why copper?

Bruce Betts: Because of that wonderful poem. I think just they... That sounds fun. Now, it's couple of reasons, but basically it's because you can distinguish in your observations what the copper is, that's in your spectra compared to what's in the asteroid, which also probably doesn't have much copper. And then you also want something that you can put inside your explosive device and that you can mold and that melts and reforms. And so it has all the properties you want with the good strength and all that good stuff, and you can get rid of it in your measurements, and know what was your projectile and what wasn't.

Mat Kaplan: If a flying saucer was detected coming toward us, and it looked aggressive, and was made out of copper, we should probably shoot an asteroid at it. You follow my logic?

Bruce Betts: Yeah, I follow it as far as I want to.

Mat Kaplan: You don't need to go any further.

Bruce Betts: I will mention another thing, which is a much, much, much, much more massive copper object was used by Deep Impact. NASA's Deep Impact to slam into a comment in 2005, and used for the same reasons, but that was a multi 100 kilogram honker copper.

Mat Kaplan: And another big impact are coming up, right? I mean, I hope that pretty soon, we're going to be catching up on the dark mission. Still slated to launch show late this year.

Bruce Betts: Yeah, we're going to slam an even bigger thing into a small asteroid. That was a big thing into a big comet that did change its course so little, and this'll be a much more significant change in a slamming into an asteroid.

Mat Kaplan: I had another funny guy, Robert Klein in Arizona. You can't stop me copper, I'm going to blow a giant hole in this asteroid [inaudible 00:48:38]. And you'll never catch me copper, because I'm going to two more asteroids [inaudible 00:48:42]. My very bad Ruggie Robinson.

Bruce Betts: No, that was a very bad impersonation of Ruggie Robinson.

Mat Kaplan: Here's another interesting one from Daniel Sorkin in New York, copper is one of those metals that humans started using very early. As a matter of fact, copper was the first metal that humans discovered circle 9,000 BCE. You could say, we've come full circle with higher [inaudible 00:49:08] too. You could, you don't have to. I am proud to let you know that our winner this week is Gilles, as in G-I-L-L-E-S. Gilles Lashonz in Vancouver, British Columbia, who indeed said it was copper.

Mat Kaplan: I love that this one was picked out by because now I get to read this. Double congratulations are due as you'll hear in a moment, Planet Fest 21 was a blast. And I met the girl of my dreams there too. Can't thank you enough TPS, Ad Astra. Wow, be sure to invite us to the wedding Gilles.

Bruce Betts: Tinder and Neil Harmony got nothing on us.

Mat Kaplan: That's why we're here to bring people together in vacuum.

Bruce Betts: It is but not necessarily a romantic way, but whatever works.

Mat Kaplan: I'll close with this from Jean Lewin in Washington, a transition metal was selected for this task to penetrate [inaudible 00:50:08] skin. Excavating what the surface masked number 29 in your program, from Cooper its symbol came projected by the SCI and copper is its name, nicely done. We're ready to move on. I got another good prize for the winner of this new one.

Bruce Betts: Name all the people who flew in space while serving in the US Congress, they were sitting members of Congress to use that odd phrasing at the time they flew. Go to contest to get us you're entry.

Mat Kaplan: There's something that is in the news, of course, I will say no more. You have until Wednesday, April 7, at 8:00 AM Pacific Time to get us this answer. And we have these books piling up at headquarters where I still have not been for now over a year. But I get sent pictures. So I know that we have a copy of the backyard astronomers field guide, how to find the best objects in the night sky are that the night sky has to offer, excuse me, by David Dickinson.

Mat Kaplan: Who has done some good stuff. He's co-author of the universe today guide to viewing the cosmos, which I think we also gave away. It's from page street publishing, and apparently it's good for both hemispheres, not East and West, North and South. And [inaudible 00:51:32] recommends it pretty highly. It's got a nice quote on the Amazon listing. So there you go, that can be yours. If a picks you out and you come up with the answer Bruce's looking for.

Bruce Betts: All right, everybody go out there and look up the night sky and think about your favorite copper object of all time. Thank you and goodnight.

Mat Kaplan: My favorite copper object has just come back to me. It was on that cave trip that I made with Penny Boston. Is a spelunker and a whole bunch of other people. When she pointed out to us on the wall of the cave in Carlsbad Caverns, the bacteria that were eating copper and excreting copper oxide. It's not like it was my property, but I own that memory. SO thank you, Bruce, for bringing it back.

Bruce Betts: Yum.

Mat Kaplan: It was delicious. It's Bruce Betts, the Chief Scientist of the Planetary Society who joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California. And is made possible by its worldly members. We're saving the world for you at Mark Hilverda is our associate producer. Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. But what you're hearing in the background right now is Exoplanets from composer, Elena Ruehr, and our guests, Natalia Guerrero, performed by the Lorelei Ensemble. Enjoy Ad Astra.