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Jessie Dotson and Geert Barentsen, Kepler’s Contributions to Astronomy

Season 1Mar 23, 2018

A conversation with Jessie Dotson, Kepler’s project scientist, and Geert Barentsen, director of the mission's guest observer office, talking about how NASA’s first planet-hunting mission has contributed so much to the field of astronomy.

NASA in Silicon Valley Podcast Logo

A conversation with Jessie Dotson, Kepler’s project scientist, and Geert Barentsen, director of the mission’s guest observer office, talking about how NASA’s first planet-hunting mission has contributed so much to the field of astronomy.


Host (Matthew Buffington):Welcome to NASA in Silicon Valley episode 83. Following last week’s conversation with the Kepler space telescope system engineer Charlie Sobeck, we’re continuing on the theme of all things Kepler. This week we’re checking in with the mission’s dynamic science duo: Jessie Dotson is Kepler’s project scientist and Geert Barentsen is director of the guest observer office. They’re here to tell us how NASA’s first planet-hunting mission has gone on to do so much more for the field of astronomy than merely finding a sky full of exoplanets. We’re entering the final months of the spacecraft collecting science data, and it’ll be going out on a high note. Jessie and Geert explain there’s a lot of exciting research going on…

Let’s listen to our discussion with Jessie Dotson and Geert Barentsen.


Host:It’s awesome having you guys back. Let’s kind of pick up where we left off. Last time that we were together chatting – well, individually with Jessie and with Geert –– talked a lot about exoplanets, a lot about the Kepler mission. A lot of stuff has changed. I know the primary mission has already concluded out. So, what’s going on in your guys’ world right now?

Jessie Dotson: So, we’re still operating the spacecraft in the K2 mode – I know people have talked about that before on the podcast – where we look at a different field of view every 80 days. We do that. We only have two working reaction wheels, and we’re kind of using the Sun to provide the pointing around the third axis. And the cool thing about looking in different areas every 80 days is we get to look at a wide variety of stars. And so, we’re still finding lots of exoplanets around different types of stars, and it’s just fascinating. Geert, you have a favorite exoplanet discovery from the last year?

Geert Barentsen: Well, actually, my favorite thing is that there are new planets every other day now.

Host: Uh-huh.

Geert Barentsen: It’s a bit like the weather forecast. In fact, the NASA exoplanet archive keeps track of them. And if you subscribe to their mailing list, they’ll send you a message every week with this list of new planets this week. It’s routine. So actually, as of last night, we now have 2,648 planets confirmed from Kepler.

Host: Oh, wow. And I’m sure that will change by the time we even have this published because…–

Jessie Dotson: It changes every week.

Host: Breaking the fourth law: that we’ve recorded it. So, it will continually change. It’s crazy.

Geert Barentsen: Every week there’s – maybe on a quiet week it will be two new planets. On a busy week, it will be a hundred, which is what happened last week, I think, Jessie.

Jessie Dotson: Yeah. Very cool.

Host: And I guess for folks who are listening, who may not have listened to the previous episodes – which I’m sure they’ll go back into the archive and learn all about everything that you guys are working – but for folks who completely are not aware, the Kepler telescope and the primary mission was all about finding exoplanets. And that primary mission has concluded. But now a lot of stuff that Geert has been working on – and also you, Jessie – of the K2 mission, there’s still about – there’s still a lot that you’re finding out about exoplanets. Am I wrong?

Jessie Dotson: Absolutely. So, in the primary mission, we looked at one field of view. We picked a very nominal part of the sky where lots of stars were, but they were kind of middle-aged stars. But now that we’re looking at different parts of the sky all the time, we’re looking at young stars, old stars, stars and star clusters, and finding planets in all these different areas. And so, the star clusters we get really excited about because star clusters are the closest thing that astronomers have to a stellar laboratory because all the stars in a star cluster have about the same age, and they were formed from, basically, the same stuff. So, they have very similar chemical compositions. So, when you look at a star cluster, any differences you see between the stars in the star cluster they’re not due to age, and they’re not due to the composition. They’re going to be due to size and other variables. And so, finding planets in star clusters is so exciting, and we’re starting to find them.

Geert Barentsen: Over the past four years of operating Kepler in the K2 mode, we looked at 20 clusters.

Host: Oh, wow.

Geert Barentsen: And now we’re starting to really find planets in them. So maybe my favorite is the Beehive cluster.

Host: Okay.

Geert Barentsen: If the listener of the podcast is an amateur astronomer, they will know this because it’s this beautiful object. If you look this time of the year, sort of in spring, if you look with binoculars towards the East just below Castor and Pollux, two famous stars in the constellation of Gemini, you’ll see this fuzzy blop. And if you point your binoculars at it, it’s this beautiful swarm of thousands of stars that fills your binoculars. So now we know that there’s at least six planets there, including an Earth-sized one – which we didn’t know a year ago.

Jessie Dotson: That’s just so cool. And the other cool thing about finding planets in star clusters is every star cluster kind of gives a snapshot of what stars look like at a certain age.

Host: Mm-hmm.

Jessie Dotson: And so, when we start to find planet systems in star clusters, we now know what a planet system looks like at 5 million years or 10 million years. The planet systems in the Kepler field, they were all kind of middle-aged stars, so it’s kind of hard to know what age those planet systems are. And understanding how planetary systems form and grow up is just a fascinating area of study that we’re just starting.

Host: I remember, Geert, when you were on you talked a lot about what you actually end up seeing when the data comes back. It almost looks just like a pixel. I remember the analogy: “You’re putting a lot of light into a bucket, and you’re measuring the differences of the light in one bucket versus what it was beforehand.” So, what do you guys see because I’d imagine if a star was a pixel, and you’re trying to understand the dimness for transits and stuff… –When you’re looking at star clusters, is that like a bunch of pixels all clumped together, or… –? I don’t know, help me out. What are you guys actually seeing? How do you determine that?

Geert Barentsen: It’s a lot more difficult because, if the star cluster is very dense, then you have to separate the flux. So, people are writing better tools and better software to separate the signals. We just had a workshop for professional astronomers in Boston last month, where we got 50 people together to exactly discuss these problems and also discuss the new scientific results they achieved using these new methods. So, this is an ongoing state-of-the-art research question: How do we get all these signals out of the data?

Host: I’m also assuming that it’s not just us looking at that data. There’s an entire community of scientists that are looking at this data and helping to pick this all apart?

Jessie Dotson: Oh, absolutely. There’s a huge number of people analyzing the Kepler and the K2 data.

Geert Barentsen: As of last month – I just looked this figure up – as of last month, there were 50 Ph.D. theses in the U.S. that were written based on Kepler data.

Host: Oh, wow.

Geert Barentsen: So, 50 times where a graduate student spent five or six years of their life working away on the Kepler data to extract all the science. There’s now 2,500 papers, peer-reviewed scientific publications, based on the Kepler data.

Host: You talked about the star clusters and exoplanets. It’s not just exoplanets. Am I right? I think at one point we were talking about even objects in our solar system and stuff. There’s a whole mix of different – –you get a lot of diversity in the K2 program.

Jessie Dotson: Because we’re looking in different parts of the sky every 80 days, we see a huge number of stuff. For instance, we look at comets.

Host: Okay.

Jessie Dotson: And we look at asteroids, and we look at dwarf planets. There was a really cool discovery that people did using K2 data where they took a look at a dwarf planet, 2007 OR10. And they took a look at – i–n the K2 data, they measured its rotation rate – so how quickly this dwarf planet was rotating – and it was rotating so slowly that they were like, “Huh. What’s going on there?” And they thought that one of the explanations for such a slow rotation rate would be if the dwarf planet had a moon. And so, they went back and looked in historical Hubble images that people had previously taken of this object –

Host: Oh, really? Okay.

Jessie Dotson: – and, because they knew to look for a moon, they were able to find it.

Host: Oh, wow. And so, then that’s those crosses of different data points just painting a broader picture and all.

Jessie Dotson: Yeah. It’s such a cool story because the spacecraft was not designed to look at solar system objects. And then you also have this thread of, you know, you can take data from the Hubble and not understand what’s there until you know what to look for.

Host: Mm.

Jessie Dotson: And that is one of the fascinating things about science data from these missions. We archive the data. We make it public. I’m certain people are going to find things in our data that we don’t know to look for yet well into the future.

Geert Barentsen: This is why NASA has multiple telescopes – because often they’re good at different things.

Host: Exactly.

Geert Barentsen: You combine them. The sum is more than the individual – –

Host:Because you have the land-based telescopes, you have space telescopes. You even have SOFIA that’s flying around, capturing – –flying telescopes. And so yeah.

Jessie Dotson: Absolutely. And one of the kind of routine things that happen with the Kepler and K2 data is – you know, we talk about, “We find planets.” Well, we do. But we find the signals of things that could be planets. When people talk about finding another 100 confirmed planets in the K2 data, they start with our signals. But then they combine that with ground-based observations to rule out some of the things that could possibly look like a planet in our data but isn’t.

Host: Okay.

Jessie Dotson: And so, all of the confirmed Kepler and K2 planets have ground observations to help us make that case.

Host: Even in the early days of exoplanets, people had seen things that ended up being exoplanets, but they thought it was something else. Surely a lot of false positives, where people thought it was; but then they didn’t want to get too over-ambitious and – –yeah, it’s science.

Jessie Dotson: That’s part of the cool part about science, absolutely. We get smarter all the time.

Host: Yeah. And then the more data points, the more stuff.

Jessie Dotson: Mm-hmm.

Host: Then it’s like years from now people will still be using this.

Jessie Dotson: Mm-hmm. We hope so.

Geert Barentsen: The science is only getting started, as far as I’m concerned. Last year was the most productive scientific year for Kepler. Even though the mission was launched in 2009, now it’s 2018 and the number of papers and discoveries is still ramping up.

Host: And this is a cool thing from chatting with people. Obviously, there’s a cool engineering story about the telescope and the reaction wheels and using the Sun to balance it out. But I think you tend to lose track between sending big hunks of metal and science in there. We’re not doing this just for fun and just to say that we can put something in orbit or have it circle around the Sun. The whole purpose of this whole thing is to learn the science about it for these discoveries. This is the whole – a –nd to be able to take it from the primary mission but getting all this extra stuff out of that is just huge.

Jessie Dotson: Absolutely. And it’s a cool story because Kepler, the spacecraft, was designed to do one thing really, really well – and that was find planets around other stars. And we can do that. But because the Kepler Spacecraft allows us to basically look at our universe with a different set of eyes than we had before in that we can measure very, very small changes of brightness, and we can look at a lot of stars at the same time, and we record the brightness every half hour continuously now for 80 days at a time, in the primary mission for almost the entire four years–That kind of high-sensitivity, uninterrupted staring, you learn so much that you can’t learn when you just look at something once a night or once a year.

Geert Barentsen: We’ve been using this capability recently, actually, to look at something entirely different, which is supernova explosions.

Host: I was right about to transition into that because I was thinking it was a couple months ago we had a whole conversation and you were talking about supernovas. And I just felt like my mind was blown. And so yes, let’s –

Geert Barentsen: Your mind will get blown.

Host: I was just like: “What?”

Geert Barentsen: Your mind was blown, just like stars blow when they supernovae.

Host: Nice. Very smooth.

Geert Barentsen: That’s what a supernova is. A supernova is what happens when a star blows itself to smithereens. And not just any star. We think the most common type of supernova is when this object called a “white dwarf” explodes.

Host: Mm-hmm.

Geert Barentsen: Now, let me briefly explain what a white dwarf is. A white dwarf is basically the core of a star that died. So, the listener might know that the reason a star like our Sun is warm and bright is because, at its core, it’s fusing hydrogen into helium through nuclear fusion.

Host: Yeah.

Geert Barentsen: And then once it runs out of hydrogen, it will maybe fuse a bit of helium into carbon and oxygen. But then what you end up with at the end of the life of a star is this big ball of carbon and oxygen in the core of the star, and often it’s no longer hot enough then to fuse those elements into heavier elements. So usually when a star dies, it’s just left with this big ball of carbon and oxygen. And so, the universe is full of these big balls of carbon and oxygen. They used to be stars billions of years ago, and now they’re dead. But sometimes – and this is not common, but sometimes these things have the most violent explosions you will ever see, explosions visible across the universe. So, this is something that happens when a carbon detonation occurs.

Host: Okay.

Geert Barentsen: This is basically a process during which, in a few seconds, the entire star heats up to billions of degrees and flies apart. All the particles that make up the star fly apart in this explosion at 10,000 miles per hour. And this is important for scientists. This is a tool we use to measure distances in the universe. And yet the reason these explosions happen is something that’s still a bit of an enigma to scientists.

Host: Oh, really?

Geert Barentsen: So, there’s a few theories. So, what people think happens is that the white dwarf must be gaining material from somewhere because we think we know, from models, that once a white dwarf becomes heavier than about 1.4 times the mass of the Sun, that’s when you get enough temperature, through gravity, to have this explosion.

Host: Yeah.

Geert Barentsen: But where does this material come from? There’s a few theories. One option is if there’s a star nearby, if it’s a binary star system –

Host: Yeah, it’s gobbling things up.

Geert Barentsen: – it might be gobbling, it might be siphoning material onto the star. That’s one option. It might also –

Jessie Dotson: Eating its neighbor.

Host: Yes.

Geert Barentsen: Eating its neighbor. A bit of cannibalism happens in the universe. Or it might be, maybe, a merger. There might be another star colliding with it. But honestly, we don’t really know. Now, the beauty is, if we use Kepler to look at thousands of galaxies, we know that we will see supernovae right when they go off just because we’ll be lucky to see a few there.

Host: You just happen to be looking at the right time.

Jessie Dotson: Yeah, you get, on a kind of -ish that’s – it’s a bit fuzzy, but you get about one supernova per galaxy per hundred years.

Jessie Dotson: So, we’re looking – right now, we are looking at just over 9,000 galaxies.

Host: Yep. And also, when that happens, it takes time for that light to even get to us. Am I wrong on that?

Jessie Dotson: True. Oh yeah, as always. There’s always light travel time.

Host: There’s always that because there’s the thing about light and how fast it travels. So even when we see one happening, it’s like it happened forever ago.

Geert Barentsen: Millions of years ago, right.

Jessie Dotson: Yeah.

Host: Before the light even reaches us.

Jessie Dotson: Yes.

Geert Barentsen: But the neat thing is that when it happens, we can actually use the first hours and the first minutes of the explosion to try to figure out what happened because if there’s a big star next to it that was being gobbled up, then when the explosion hits that star, it should give a blip in the light. And that’s exactly what Kepler is doing right now, which is super-exciting because this is like Nobel Prize-winning type science. There was a Nobel Prize in 2011 that used these types of supernovae.

Host: And what are you guys able to learn from these supernovae, from these measurements that you didn’t know before? Or what are you hoping to learn, or –?

Jessie Dotson: Well, just like Geert was explaining: for this particular type of supernova, there are different explanations in terms of how it starts.

Host: Mm-hmm.

Jessie Dotson: And those different explanations predict slightly different behavior in how the brightness of the supernova changes at the very beginning of the explosion. And since we are staring at all these galaxies, we see it as soon as it starts to go off, as soon as the light hits us.

Host: Yeah.

Jessie Dotson: But we get to see the early explosion. Generally, when people observe supernovae from the ground, you do supernovae searches. And so, you look back at your galaxies and monitor them every several days and look for large changes in brightness so that you can pick it up. But that means you don’t see the explosion right as it starts. We get to see the explosions right as they start.

Host: Is that helping to better understand the formations of the galaxies or just stars, or is –

Jessie Dotson: So, what this will do is this will help us disentangle why the supernovae happen. Supernovae, we may not realize it, are just important to life as we know it. All the heavy elements –

Host: I was going to say –

Jessie Dotson: – the gold in your wedding ring or in your ears, those came from stellar explosions like supernovae. And so, elements and chemicals that we take for granted are from –

Host: The atoms that are us.

Jessie Dotson: – are from stellar explosions that happened a long, long time ago.

Geert Barentsen: Every atom heavier than nitrogen was made in a supernova, including all the precious metals in your iPhone or Android device.

Jessie Dotson: And then the other really cool thing about supernovae is because we underst – while we don’t understand exactly how the white dwarf accretes enough material or gets enough material that it breaks this 1.4 times the weight of the Sun’s limit –

Host: Yeah.

Jessie Dotson: – that triggers the explosion, once the explosion happens, we understand that really pretty darned well. And so, we can use supernovae as what we call a “standard candle,” where we know how bright it should be. And so, if we measure how bright it looks to us that actually tells us how far away it is.

Host: Mm-hmm.

Jessie Dotson: And measuring distances in space is hard.

Host: Yeah.

Jessie Dotson: And so, we kind of have this whole ladder. We’re like: We measure distances nearby with parallax, and then we measure distances further out by looking at Cepheid stars. But supernovae are so bright that they let us measure the distances way, way far out there.

Host: And this is not in our galaxy. This is not in the Milky Way. These are other galaxies, huge supernovae.

Jessie Dotson: Yes, very far away.

Host: And then that becomes – talk a little bit about the standard candle thing. Is that just measuring everything in its vicinity? You can understand?

Jessie Dotson: No, it tells you how far away that galaxy is –

Host: Okay.

Jessie Dotson: – how far away the galaxy where that supernova went off is. And that helps us map the 3-D – That just helps us map all the distances and try to get a 3-D image of our universe. And people use that to help measure the expansion rate of the universe, which then folds into: Does the universe keep expanding forever, or does it collapse back in on itself? That’s why these standard candles are so important: to help us understand, quite honestly, the future of our universe.

Host: I’m just curious: What does that show up like? You talked about seeing exoplanets. It’s like the pixel with a bunch of light in the pixel, and then the clusters are harder to disentangle. Is it just a super-bright pixel that’s – ?

Geert Barentsen: Basically. So, we look at galaxies. We look at 10,000 galaxies right now. So, you have an image of a galaxy every 30 minutes, and then all of a sudden, you’ll see this blip appear. It will slowly brighten for about two weeks until it reaches maximum brightness – you know, billions of degrees temperature – and then it will slowly tail off. So, you see this bright spot suddenly appear in a galaxy.

Jessie Dotson: And what’s really cool – so right now we are, like I said, observing over 9,000 galaxies. We’ve been at it since early December. When we observe with K2, because we have to balance against the Sun, we can either look away from the Earth or towards the Earth. And we usually look away from the Earth.

Host: Yeah.

Jessie Dotson: But this time around, we’re looking towards the Earth. On one hand, it causes a problem because that means the Earth goes across our field of view and it’s –

Host: It’s bright.

Jessie Dotson: – a bright thing that gets in the way of things we want to observe. But with the geometry we’re currently in, looking towards the Earth means that things we’re looking at with the spacecraft are also observable from Earth at night. And so, there are telescopes all over the world right now that are monitoring the same galaxies we’re looking at. As soon as they see evidence of a supernova – and they don’t see it right away, but they’ll see it a couple days after the explosion starts – an alert goes out. And then there are telescopes across the planet that are then doing follow-ups so they can get an idea of what the chemistry is of the supernova.

And so, when our data comes to the ground, there are teams basically waiting to combine our data of this high-precision, early time changes in the brightness with the data they’ve taken on the ground of the chemistry of the supernova to really inform the theories. And so, for instance, we know there is approximately 20 supernovae that we have data on right now. And Geert has a favorite.

Geert Barentsen:There was a really nice one a few weeks ago. It happened to be on Super Bowl Sunday, so informally we called it the Super Bowl Sunday Supernova.

Host: Nice.

Geert Barentsen: But astronomers actually like to give really dull names to things, so the official name is SN2018oh.

Host: Oh, you can do better than that.

Geert Barentsen: Well, it went off in a galaxy called UGC4780. How about that?

Host: Nice.

Geert Barentsen: And so, the names are a bit dull, but actually this galaxy is so nearby that it means that we get one of the best observed supernovae ever recorded by astronomers. So, this particular galaxy is just 160 million lightyears away. Now, okay, that’s kind of far away.

Host: Yeah.

Geert Barentsen: It takes 160 million years for the light to travel. But if you know that the edge of the observable universe is 50 billion lightyears away –

Host: Oh, yeah. Relatively speaking, it’s next door.

Geert Barentsen: – it’s less than a percent from the edge we can see.

Host: Yeah.

Geert Barentsen: So, it’s sort of like being in San Francisco and just taking a ride to the airport.

Jessie Dotson: If you think of the size of the universe as the size of the planet.

Geert Barentsen: Right.

Host: It’s super-close.

Jessie Dotson: Yeah. It’s the airport from downtown.

Host: Yeah.

Geert Barentsen: Now, all that data is still stored on the data recorder on the spacecraft.

Host: Okay.

Geert Barentsen: And we have to wait until the spacecraft finishes this campaign, as we call it. That’s what we call the period where we look at one specific field. The spacecraft is going to turn its high-gain antenna, it’s big antenna dish, to Earth actually this upcoming Sunday, at the time of recording, to point its antenna at the Deep Space Network, which is this big set of – the biggest radio antennas that NASA has to talk with faraway spacecraft.

Host: Mm-hmm.

Geert Barentsen: So, we’re going to get the data on Earth really soon, and we can’t wait to actually see what happened. We know there was a supernova. We got a few images from Earth, and spectra. So, we know something about the chemistry. But now Kepler is really going to show us what happened in the first minutes and first hours of this event.

Host: And so maybe talk a little bit about that lifecycle of these campaigns. It’s a certain amount of time where it’s getting the observations, but then it’s got to skedaddle and move into a different place where you can take down the data. Then does it immediately go and look for more things, or how do these campaigns overlap? And how does that work?

Jessie Dotson: So, the campaigns don’t overlap at all.

Host: Okay.

Jessie Dotson: And actually, we plan out – oh, God – a year in advance what part of the sky we’re going to be looking at. And then astronomers from all over the world propose which parts of our – which pixels we should download. We have a huge field of view, and we don’t have enough room in our solid-state recorder or enough bandwidth with the Deep Space Network to store data on all the stars that are in our field of view. So, astronomers, they propose which to observe. And we tend to observe something on the order of 20,000 to 30,000 targets in any given campaign.

Host: Mm-hmm.

Jessie Dotson: And so, all of that prep work goes on in kind of like the year prior to the campaign. And then we take those target lists that are the top reviewed. We have other scientists take a look at the arguments that people propose and say, “Yea, we think these are the best ones.” We make a target list. We have folks here who run the pipeline to create the target lists. There are folks at Ball who then turn those into spacecraft commands.

Host: Okay.

Jessie Dotson: Those are then uploaded to the spacecraft during one of these periods when the spacecraft is turned so that the high-gain antenna is pointed at Earth. We upload those commands. The spacecraft then points to the part of the sky we want to observe, and it stays there for 70-85 days depending on the length of the campaign. It kind of phones home twice a week. It just kind of says, “We’re still here. We’re still here.”

Host: Nice.

Jessie Dotson: “We’re still here.” And the spacecraft is further away from us right now than the Earth is from the Sun.

Host: Oh, wow. Okay.

Geert Barentsen: Ninety-four million miles.

Jessie Dotson: It’s in an Earth-trailing orbit.

Host: Mm-hmm.

Jessie Dotson: And so, when we’re using the “We’re still here” communications, it’s 20 bits per second.

Host: Oh, wow.

Jessie Dotson: It’s super-slow. Very little data can get through. And we’re using 34-meter or 70-meter radio dishes depending on which contact we have. So that goes on for, like I said, about 80 days. And at the end of the 80 days, we stop taking science. We reorient the spacecraft so that our high-gain antenna is pointed towards the Earth. We schedule a whole bunch of DSN time. The DSN is really fascinating, too.

Host: Mm-hmm.

Jessie Dotson: NASA has three DSN stations around the globe –

Host: And “DSN” stands for –?

Jessie Dotson: Deep Space Network.

Host: Okay, awesome.

Jessie Dotson: – oriented around the globe. And the idea is so that basically, no matter which part of the sky you’re looking at, you can see one of the DSN stations.

Geert Barentsen: It’s in Spain, Australia, and then one in California.

Host: Oh, wow.

Jessie Dotson: So, they’re basically at thirds around the globe, okay?

Host: Nice.

Jessie Dotson: And so, in these campaign breaks, we get 70 hours of DSN time. We download the data we just took. We upload the next target list. And then we reorient the spacecraft to the next part of the sky, and we start the whole process over again.

Host: So, I think for a lot of people, Cassini is probably fresh on their brain – spacecraft collecting data, and then it ended in this trail of glory as it burns up into the atmosphere. So obviously these big space telescopes, they launch, and then they inevitably are going to have an end-of-life part.

Jessie Dotson: Kepler was designed to do one thing very, very well. And it did that very, very well. But it is so good at what it does that it has become useful for so many – it’s so good at finding exoplanets; supernovae; it might help us understand the fate of our universe depending on what we learn from the supernova campaign; dwarf planets. We haven’t even talked about all the things that Kepler has taught us about stars and the interior of stars. That’s a whole other half hour. But Kepler is so good at what it does, and NASA so values what we get out of Kepler, that we have the privilege of having the opportunity to run this spacecraft for as long as it can go.

Host: Yeah.

Jessie Dotson: And we know it’s going to stop at some point in the not-too-distant future – it only has so much fuel on board – but we’re going to keep eking all the science out of it as long as we can.

Host: And so, for folks who may not be familiar, what is that going to look like?

Jessie Dotson: We don’t know.

Host: We have no – We just literally don’t know.

Jessie Dotson: So, we have very clever – so, every system on board this spacecraft is beyond its designed lifetime, okay?

Host: Okay. People think of a computer. It’s got its time, and then at a certain point you have to replace it.

Jessie Dotson: Yeah. You know how you buy something and it’s got a year warranty?

Host: Yes.

Jessie Dotson: And then on Day 367, it stops working?

Host: Yes. Exactly, exactly.

Jessie Dotson: That’s not our spacecraft. Everything is well past its warranty and is working, but we know something is going to break. And we also know, if nothing breaks, we’re going to run out of fuel. We don’t know exactly when, but we know we’re going to run out of fuel.

Host: Yeah.

Jessie Dotson: And so, we’ve put a few steps on board where we’re doing a little bit of extra monitoring at the 20 bits per second on those couple phone homes to kind of give us an idea: Are things behaving like we expect or not? So far, they are behaving like we expect. But we’re watching it. And when it starts acting up, we’ll deal with that.

Host: It’s one of those things where it’s like since everything is past its expected lifespan, you know at some point in time you are going to run out of fuel –

Jessie Dotson: Yep. Yep.

Host: – or something is going to haywire that hopefully you can fix but maybe not.

Jessie Dotson: Yep.

Host: And that’s not a surprise. This is purely expected. It’s a thing that you know is going to happen.

Jessie Dotson: It’s expected. We just don’t know when.

Host: Okay. And until we know when, you’re going to get as much out of it as you possibly can.

Jessie Dotson: Absolutely. And we know it’s going to be soon-ish.

Jessie Dotson: We’re not going to be here a year from now having the same conversation.

Host: Yeah. It’s just fascinating. And it’s obviously a testament to the scientists and to the engineers that put the thing together and that are eking this data out of it. But as much of an engineering marvel as it is, you always want to keep the focus on “Why?” because we’ve learned so much, and so much above and beyond what was even expected at the time of launch.

Jessie Dotson: Oh, absolutely. And it’s trite. You know people talk about, “It takes a village to raise a child?”

Host: Mm-hmm.

Jessie Dotson: It takes a small town to design, run, and understand what you can get out of a successful science mission. People have worked on this mission for – We’ve been in space since 2009. People worked on it for years and years before that – engineers, scientists, accountants, citizen scientists. We have so much data that there is a huge citizen-science program where Geert was involved in a really cool discovery that was found by a mechanic in Australia.

Host: That is awesome.

Geert Barentsen: A car mechanic found a planet system in the Kepler data just last year, yeah – because there’s so much data. And in some ways, the number of discoveries, the number of planets we find are limited by the person power, by the number of astronomers that have time to write up the papers and do all the analysis work, to the extent that we frequently now have just people that are not professional astronomers but are good with data or just want to volunteer their time to go and find planets in our data – because with K2 now, we have observed more than 300,000 stars. To try to go through each of them by eye, that’s a lot of work.

Host: And it’s important noting, from what you guys even said before, even long after the fuel runs out or it can no longer phone home and say, “I’m here,” there are still going to be papers written about the data that as been collected.

Jessie Dotson: Oh, absolutely. There’s no reason to think it’s going to stop. And if you look at the primary Kepler data – we took data in that one field for four years – people are still writing papers about that data four and a half years later. More Kepler papers were written last year than the year before.

Host: Oh, wow.

Jessie Dotson: And more written the year before that, and the year before that. And so, there’s so much science to be had, people are going to continue to mine this data at least for the next decade.

Geert Barentsen: And then when NASA’s next new flagship telescope gets launched, James Webb, it is going to spend some of its time on actually studying some of these Kepler discoveries. So, in some way, the legacy of Kepler will continuously live on as we get better telescopes and better instruments to put our Earth into context.

Host: Yeah, because I’m sure that will help decide where that telescope looks. But then also, when it gets data, it can compare the data to other stuff, and then the land-based telescopes and –

Geert Barentsen: NASA is on this mission to answer the question, “Are we alone?” And we don’t know the answer to that question right now. But I think we’re going to continue to see exciting new missions that are going to try to answer that question because it’s something that, I think, fascinates me a lot and fascinates a lot of people because it’s kind of fun to sort of know the context around you.

It’s like when you travel: It’s so much fun to travel and discover that maybe cars drive on the left side of the road, or maybe coffee comes in really small cups. And that helps you understand what’s different in some cultures but also what we all have in common as the human species. And I think, for me, that’s why Kepler is such an exciting mission. It really sort of helps us understand humanity and actually connects us in some way.

Host: Yeah, because even the thing of the core parts of NASA. It’s not just about exploration and human exploration. It’s about revealing the unknown. It is understanding our universe, and it’s like: And you can’t do that without this.

Geert Barentsen: And ultimately, it’s always about us. It’s always about understanding the universe because we’re part of it. It’s our universe.

Host: So, for folks who are listening, if you have any questions for Jessie and Geert, we are @NASAAmes. Also @NASAKepler, as well. So, if you have any questions, feel free to just go ahead and ping us on social media. We typically use the hashtag, #NASASiliconValley. Thank you so much for coming over. This has been super fun.

Jessie Dotson: Oh, we love to talk about the science and about the mission. Just try to keep us away.

Host: Nice. Well, thank you, again, to our returning Jeopardy champions. I think you’re the first ones to come together for take 2, so – but I’m sure you’ll be back for more.