A Great Space Observatory Goes Dark: The Legacy of Spitzer

Mat Kaplan: [00:00:00] A great space observatory, 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. After 16 years of spectacular infrared astronomy and astounding discoveries, the Spitzer Space Telescope has been decommissioned. Three leaders of that groundbreaking mission will join us to examine its rich and continuing legacy of science. First, The expanse, now Star Trek: Picard, good times for TV science fiction. We'll talk with Emily Lakdawalla about the breathtaking depiction of Mars in Picard. And though it may be a close shave, we'll save time for What's Up with Bruce Betts.

The latest addition of The Downlink has been posted by Planetary Society Editorial Director Jason Davis. Here [00:01:00] are highlights from that skillfully curated digest of space exploration news. NASA's stalwart Voyager II space craft automatically and safely switched off its science instruments after overdrawing its available power. The space craft, which launched almost 43 years ago on its grand tour of the outer planets, is currently exploring interstellar space. Its radioactive power supply fades by about four watts each year. Engineers expect it to return to normal operations soon.

The International Space Station is getting a new privately operated module as part of NASA'S plan to open up the station for commercial opportunities. Axiom Space plans to launch the module in 2024 and connect it to the station's forward-most port. That port was once used by visiting space shuttle crews. NASA's James Webb Space Telescope is unlikely to meet its March [00:02:00] 2021 launch date, according to a new report from the Government Accountability Office. The successor to the Hubble Space Telescope will serve a broad range of astronomers and planetary scientists by studying some of the most distant objects in the universe and directly imaging exoplanets. But first, it has to get off the ground. NASA still hopes that will happen next year.

And NASA has marked its annual day of remembrance to honor astronauts who have perished on missions over the years. The day is timed to coincide with several tragic space anniversaries: the Apollo One fire on January 27th, 1967, the Challenger disaster on January 28, 1986, and the loss of Columbia on February 1st, 2003. You'll find links to explore these and other recent space developments at Planetary.org/Downlink.

He's back, and I couldn't be happier. After a hiatus of 18 [00:03:00] years, Patrick Stewart has returned as the indomitable Jean-Luc in Star Trek: Picard, now airing on CBS All Access. Mars has made it into the new series, and my colleague, Planetary Society Solar System Specialist Emily Lakdawalla couldn't be happier about the planet's supporting role. Emily, were you anticipating the premier of Star Trek: Picard as much as I was?

Emily L.: You know, likely not, but I am a huge Star Trek fan-

Mat Kaplan: [laughs]

Emily L.: ... and especially of Star Trek: The Next Generation. So I was looking forward to it with, uh, anticipation, but also trepidation, because I- I can never trust creators to take things in a direction that I approve of. And I of course have my own ideas.

Mat Kaplan: [laughs]

Emily L.: But I really did like what they did with the show, and I especially liked the special effects, including those on Mars.

Mat Kaplan: You wrote about the nice treatment that Mars gets in this show, at least visually. [laughing] It's not treated very well in the plot. In a recent blog post, which we will put up on this week's [00:04:00] episode page, Planetary.org/Radio. Of course, it's listed separately under all of the blogs there on the Planetary Society site. Tell us why you were so impressed.

Emily L.: Well, first I'll say, spoiler alert. If you want no spoilers about the episode, stick your fingers in your ears-

Mat Kaplan: [laughs]

Emily L.: ... and go, "La, la, la," for a few seconds. But I was actually at the premier with a friend of mine, uh, Swapna Krishna, who's writing all the recaps. We were watching the opening of the very first episode, and- and Mars appears on the screen, and it is so recognizably Mars. It's just thrilling to see it spread out on the giant screen at the Cinerama Dome. And I actually said out loud, "Oh, hi Mars."

Mat Kaplan: [laughs]

Emily L.: And then Mars blows up. [laughing] And it was just the most, uh, for ... I don't know why it was so gratifying. I just loved the, I guess, the bravery of blowing up an entire planet in the opening moments of a- of a new science fiction series, a very bold move on the part of the writers I think. [laughs]

Mat Kaplan: It was. And- and then you had a conversation with the, uh, special effects supervisor, and I guess he was pretty gratified by your reaction.

Emily L.: He was. So I spoke with Jason Zimmerman who is the [00:05:00] VFX supervisor for the series and also for Discovery. And he talked about how important it is in the Star Trek franchise to get as many details correct as they can because their fans hold them to that kind of accuracy. And even the fans, he said, among the other, uh, VFX workers on the project. And so they do really try to get it right. Um, they did a lot of image research in order to get the colors right, to get the atmosphere right, to get the geography right. And so it really is shockingly recognizable. And he was very pleased to hear that- that I, being a person who knows a thing or two about Mars, [laughing] recognized it and thought they did a good job.

Mat Kaplan: Well, needless to say, I am hugely envious of you getting to see those first few episodes on such a huge screen. But I'm- I'm looking forward to watching episode number three. Before I leave you, as you know, I got to talk to, uh, leaders of the Spitzer Space Telescope project, just ended last Thursday. Any thoughts about that?

Emily L.: Well, Spitzer is one of those fond goodbyes where it's always [00:06:00] sad to lose a spacecraft, but it was far beyond its prime mission, and it did so much. Um, for me, I was ... I've recently been researching exoplanets, and Spitzer is one of the, uh, tools that we use to actually figure out what exoplanet atmospheres are composed of. So to the extent that we can actually describe an exoplanet in any way, figure out what's floating around in its atmosphere, we have Spitzer to thank. So I'd like to ... If you could pass along my thanks to them I'd very much appreciate it. Was a great, great mission, and I hope that everybody involved with it gets to go on and do great things with James Webb.

Mat Kaplan: That is a wonderful message that I'll be happy to pass along. Thank you, Emily. And, uh, look forward to talking again soon.

Emily L.: Thank you, Matt.

Mat Kaplan: That is the Planetary Society's Solar System Specialist Emily Lakdawalla.

NASA has a grand vision, build four telescopes and put them in space where there is no pesky atmosphere to interfere with their work. Each would concentrate on a different part of the electromagnetic spectrum. Compton handled [00:07:00] gamma rays at the most energetic end of the range. The Chandra X-Ray Telescope is still up there delivering great science, as is the best known of these sisters; that would be the Hubble Space Telescope, optimized for visible light and the near infrared. Between Chandra and Hubble was the Spitzer Space Telescope. Though earlier infrared instruments had pave the way, nothing could touch the power of Spitzer when it was launched in 2003. Part of that power was enabled by the exquisitely sensitive liquid helium-cooled detectors it carried. That liquid helium ran out in 2009. But Spitzer was able to continue use of some instruments through its innovative reliance on radiant heating, something you'll hear my guest talk about in the extended celebratory interview you're about to hear.

You'll also hear that though the telescope faced increasing engineering challenges, it was primarily NASA's limited budget that led to the [00:08:00] agency's decision to end the mission. Here's the soundtrack for a brief video that documented that bitter sweet event. It is January 30th, 2020.

Speaker 3: Good afternoon. I'm welcoming all the family and friends of the Spitzer Space Telescope as we see the end of mission today. It is a legacy, and we are here to celebrate the Spitzer Space Telescope.

Mission Manager: We confirm the loss of the high gain antenna signal at 223031.

Thomas Zurbuche: The first thing we think about, of course, is the science. But immediately with it we think of the team. Right?

Speaker 3: Mm-hmm [affirmative].

Thomas Zurbuche: The team exceeded any and all expectations here. The team of people within NASA JPL, but also contractors, Lockheed Martin, all these people who brought their best to the table to help us look at the sky in a new way.

Mission Manager: This is mission manager. Go ahead.

Speaker 6: Mission manager, loss of signal has been confirmed. Spitzer entered safe mode at [00:09:00] 223031.

Joseph Hunt: So at this time, all of the members that supported the mission that's in the friends and family area, could you please stand up to really acknowledge all of the great accomplishments that we have had with the Spitzer Space Telescope. It's a can do, will do attitude that makes these things possible. At this time, I will declare the Spitzer Spacecraft decommissioned.

Michael Werner: If you understand how Spitzer works, how intricate and well tuned it it, and how it represents the efforts of thousands of people, you appreciate what human beings are capable of.

Mat Kaplan: Among the people you just heard was NASA's Associate Administrator for the Science Mission Directorate Thomas Zurbuchen. Other voices belong to two of my three guests for this special look at the [00:10:00] legacy of the Spitzer Space Telescope. Project manager Joseph Hunt made the actual announcement from the Jet Propulsion Laboratory. And the last speaker was Michael Werner, Chief Scientist for Astronomy and Physics at JPL and the Spitzer Project Scientist. Mike has been a driving force for Spitzer since 1984. He's just written a book about the mission, something you'll hear about during What's Up, because we'll be giving a copy of that book away.

Just four days after the end of the mission, Joseph and Mike arrived at Planetary Society Headquarters with Sean Carey, Manager of the Spitzer Space Science Center at Caltech. After a quick tour, they joined me in our small studio.

Gentlemen, welcome to the Planetary Society. It is such an honor to have leaders of this just completed mission, this grand observatory that has, uh, helped us learn so much more about our solar system, our galaxy, [00:11:00] our universe. Thank you for being a part of this and, uh, for coming on Planetary Radio.

Michael Werner: Thank you.

Sean Carey: You're very welcome. Yeah, thanks for having us.

Mat Kaplan: Let's start with the basics before we get into some of the accomplishments of the Spitzer Space Telescope. Michael, I think I'll start with you on this. Apologies to members of our audience who have heard us talk before about why it's so important to do infrared astronomy. Give it to us again, please. Why infrared, and why in space?

Michael Werner: Good questions, Matt. We describe the unique perspectives that the infrared brings on the study of the universe in a quick slogan: The old, the cold, and the dirty.

Mat Kaplan: [laughs]

Michael Werner: Which is not a unreleased Clint Eastwood movie.

Mat Kaplan: I was gonna say [crosstalk 00:11:44]-

Michael Werner: But it summarizes what we can uniquely do in the infrared. The old, uh, refers to the fact that we can look back in time because the expansion of the universe brings the light from very distant objects seen as they were billions of years ago to us in the [00:12:00] infrared. The cold alludes to the fact that, uh, every object in the universe radiates in a wavelength band which is proportional to its temperature. Cooler the object, the longer the wavelengths it radiates at. And so infrared wave radiation, which is longward of the visible band that we can see with our eyes, comes to us preferentially from cold objects, from planets, comets in the solar system, from material around stars, from exoplanets, planets orbiting other stars, and from the space in between the stars where new generations of stars will be forming.

And the dirty, uh, alludes to the fact that cosmic dust, minute particles of, uh, graphite, minerals, organic materials, is a ubiquitous constituent of, uh, astrophysical systems. Clouds of dust, which are opaque in the visible and produce the grand dark lanes one sees in a picture of the Milky Way Galaxy, for example, those clouds are often transparent in the infrared. So in the infrared we can [00:13:00] see through these dust clouds to what lies behind. And in other circumstances, the dust and the clouds will absorb, uh, light from stars and reradiate it in the infrared. So the old, the cold, and the dirty is our, um, marching song.

Now, why we do this in the ... in space is pretty easy to understand. You might think, "Well, this is great. Let's put an infrared instrument on a big telescope on the ground and let's go to town." In fact, people have done that. But it hides the fact that the surface of the Earth is a poor environment for infrared astronomy for sensitive observations. And the reason for that is because the temperature of the atmosphere and the telescope are such that they produce copious amounts of infrared radiation, basically making the sky very bright. So doing infrared astronomy from the ground is like doing visible wavelength astronomy at high noon.

Mat Kaplan: Ah.

Michael Werner: We come back at night with a- with a moonlit night, moonless night; the sky is very dark at [00:14:00] visible wavelengths. To get the analogous effect in the infrared, we go into space where there's no atmosphere to bother us. We cool the telescope so it's not producing any infrared emission. And that combination, uh, makes Spitzer very, very sensitive. Spitzer's, although it's only an 85-centimeter diameter telescope, is as sensitive as it ... more sensitive than a 10-meter telescope on the ground-

Mat Kaplan: Wow.

Michael Werner: ... because it operates against the dark sky. In addition, and this is also very important, being in space, we get access to the entire infrared spectrum. And the molecules that absorb infrared radiation as it tries to get to us through the atmosphere, molecules of water, carbon dioxide, CO, and so forth, are no longer an issue. So we have a full view of the full infrared spectrum at sensitivity levels which are unapproachable from the ground.

Mat Kaplan: Well and good. It's a great deal more complicated than just saying, "Okay, no problem. We'll [00:15:00] throw one together and- and put it up there." Right? I mean, there was so much technology that had to be developed to make this scope capable of doing what it ended up doing for nearly 17 years.

Michael Werner: Let- let me make a quick comment about that, [crosstalk 00:15:14]-

Mat Kaplan: Sure.

Michael Werner: You have to recognize that Spitzer was not the first infrared telescope in space.

Mat Kaplan: Yeah.

Michael Werner: So some of the technology had been proven previously. But we took the technology to new, uh, dimensions or new extents in a couple of important areas. One is we had much better and larger focal plane detectors with many more pixels than had been used in the past. And the second is we developed a novel way of keeping the telescope cold, which relied on what's called radiative cooling, where you lose heat into the deep, dark blackness of space, deep, dark, cold blackness of space, rather than losing- dumping the heat into a- a cryogenic, uh, container of some kind. And- and that radiative cooling, as [00:16:00] we call it, stood us in very good stead and allowed us to have 16+ year mission, rather than the five or six years that we were hoping for at launch.

Mat Kaplan: But you got those five or six years as well when you were still able to operate cryogenically. We're gonna come back to that-

Michael Werner: Okay.

Mat Kaplan: ... but I want to talk with- with really any of you about the difficulty of designing a device like this that was able to last for as long as it did in space, which is a pretty nasty place, and do great science. Joseph.

Joseph Hunt: Designing a spacecraft like this to operate way beyond the initial mission plans, uh, means that you have to revisit and reassess the operations based on the change in your science plan or your science objectives. As Mike was talking about earlier, uh, to cool the spacecraft, and how we operate it during the cryogenic phase, uh, when [00:17:00] you look at the longevity of the mission and talk about, uh, the different mission phases, well, the science objectives kinda changed also. So what you had was some very, very clever engineers and scientists that was able to take, uh, such a robust spacecraft and make the necessary changes to enable it to be able to return science in those modes.

Mat Kaplan: And yet I know as with pretty much every mission that's ever gone out there into the black, there were challenges that came up along the way. Sean, I want to go to you. We haven't heard from you yet. Yeah, you have this wonderful telescope, this instrument up in space. But it's ... A- a lot of what Spitzer has been able to accomplish was because of the infrastructure here on the ground. And you managed the center that was in charge of that's- all that work, the science anyway.

Sean Carey: That's right, Matt. With Spitzer, it was important to listen to the community doing the science, and base the changes that we made as we went along [00:18:00] on the science needs of the community. So and particularly in the case of exoplanets, that was a area of study that Spitzer wasn't designed to do very well, do some things with very distant, uh, very warm planets. That was one thing that Spitzer would look for. But these transiting exoplanets, of course, that wasn't an area of science that was available when Spitzer was designed, so we kinda had to retrofit that. And of course, the problem being since Spitzer's in this Earth-trailing orbit, which is one of the ways that it stays very cool is that it's very distant from the Earth, as you can't go and modify it in any way. Right? The space shuttle wasn't accessible to-

Mat Kaplan: Yeah.

Sean Carey: ... to change it. So what you had to do is everything in software and kind of repurpose bits of existing hardware on Spitzer to try to make- make the best possible opportunities for doing science with what we had available. And fortunately, Spitzer was was really well designed. It had some very key pieces of equipment that we were allowed to repurpose and then integrate into the observa ... the new [00:19:00] science observations we were doing for exoplanet.

Mat Kaplan: That's another thing that you hear from virtually every mission, not only coming up with novel solutions to a problem when something goes wrong, but finding capabilities in a spacecraft that you never expected would be there.

Michael Werner: Mm-hmm [affirmative]. Yeah, people are very, very clever.

Mat Kaplan: [laughs]

Michael Werner: And with Spitzer, as Sean said, we had a very simple bust robust design which could accommodate being used in ways that weren't envisioned-

Mat Kaplan: Yeah.

Michael Werner: ... when we were designing and- and specifying the requirements back in the 1990s.

Mat Kaplan: Let's talk about some of the accomplishments. And I'm glad you've already brought up exoplanets because perhaps the most famous of the discoveries made by your telescope involve some planets that maybe weren't so different from ours, those seven TRAPPIST-1 worlds. Uh, Sean, I- I know you said, and this was I think maybe three years ago, that you thought this was maybe the most [00:20:00] exciting discovery to come out of the mission. Three years later, do you stand by that?

Sean Carey: Yeah, I- I still do, because the potential for understanding, uh, terrestrial-like planets, but maybe not terrestrial, because we have no idea about their atmospheric composition or their chemical composition in the TRAPPIST system is- is huge. Um, because one of the things we know now, or we know the densities of the planets, so we have a good estimate of what their bulk composition is. So the densities are known to better than 12%. I mean, the only way you can do that any other way is to be able to fly something to the planet, you know, and really measure its radius, get a good idea of its surface gravity. We know something about the surface gravity of these planets, and that's pretty profound. And since the system's so close, in any of these transiting exoplanets you're looking at a contrast between the planet and the star. So smaller star, bigger planet, means you get a larger contrast. And so for Earth-sized planets you want to look around a small star like the TRAPPIST-1 star.

They're also warm-ish ... Some of them are warm-ish enough that we may actually be able with future [00:21:00] instruments to be able to see the emission coming from the planet itself. So you're having the potential of seeing something that's terrestrial like probably a little bit warmer, but be able to measure the surface temperature of that. So that's a ... I think those are really interesting things. So I think we're really just getting started understanding the TRAPPIST system. And then since there's seven planets there, what you can do is comparative planetology. You can kinda say, "Well, these all formed from the same system, right? So they have to have common properties." And when you see differences in those planets then you're understanding something about the formation of a system, which then we can apply to looking back to the formation of our own solar system, of course, and also think about what that implies for forming other systems.

Mat Kaplan: Yeah. And I know that it wasn't just the capabilities of the telescope, but the fact that you were able ... Well, this is a capable, but the fact that you were able to basically stare at this star for, first I read 500 hours, to make the discovery. But then an additional 500. It was like 1,000 hours. [00:22:00] How much of an engineering challenge is something like that, Joseph?

Joseph Hunt: Well, the engineering challenge due to the time with this observation being made, right, uh, to go back a little bit because I- I wanted to say earlier, that's a very good point you're bringing up. The en- engineering challenges actually started when our orbit geometry started to change. Initially, in the primary mission we kept the orbit geometry such that 30 degrees was the limit. And this 30 degrees that I'm talking about is the spacecraft-sun angle. And that angle was designed to keep the sun on the solar panel and keep the spacecraft power-positive while having a communication session, uh, with the Earth. As you got into the timeframe where you're actually doing the TRAPPIST observation, uh, with those 500 hours or- or so, uh, you have several communication periods. Right? Several communication contact phases with the Earth where you're playing back the data. So [00:23:00] it's just not one continuous observation. It has several times that you're contacting to Earth to play back the data based on how much memory is being used aboard the spacecraft.

The challenge that comes there is the angle that we talk about, of 30 degrees, increased. So we actually increased over 20 degrees, uh, over the 16-year period.

Mat Kaplan: Wow.

Joseph Hunt: Right? So what this means is you have a bigger challenge- challenge where cool and recharge and keeping the spacecraft powered.

Mat Kaplan: 'Cause you could only run a battery for so long.

Joseph Hunt: Yes. You can only run on battery power so long. But when that angle increased, right, when we get up to now when we end the mission at about 54, uh, close to 55 degrees, you're totally on battery power only. Right? Which mean, uh, now you're at an angle such that the sun is actually going beneath the solar panel that was designed to shield it from the sun, and heating up some components underneath.

So we got into [00:24:00] this engineering challenge called Cool and Recharge. Right? And we kinda, uh, do a trending of all of our internet data across each down link across each phase of the mission. So during these phases you can see how the telescope is beginning to heat up. You can see how the batteries are performing. In doing so, you characterize how long you can have a communication session-

Mat Kaplan: Yeah.

Joseph Hunt: ... with the Earth without depleting the battery power.

Mat Kaplan: And this is what eventually killed you, right? I mean, this is why, uh, largely why, the mission had to end when it did?

Joseph Hunt: Well, we have overcome those type phases. So I wouldn't say that's what killed the mission.

Mat Kaplan: Oh, okay.

Joseph Hunt: It ... So what happened was initially early on we had a contact with the spacecraft twice a day. As you get out into 16 years with this old Earth probe angle, right, with the sun now, you have one contact every 24 hours. Now, when you start having this contact with [00:25:00] you using the batteries only, not on the solar panel, you- you're starting to use more of the battery power. As the battery power goes down, you have ... and you heat up, you have to come off the Earth, go back to sun point to charge the batteries and to cool the spacecraft down.

So what happened in our trending is, uh, time on Earth, the communication sessions, they changed. They began to get shorter. Right? So it's not like you can't communicate with Earth. And the strategy here is based on the observing mode and the data collection process, you just determine how long those down links are gonna be, what those communication sessions are gonna be, and how long do you need to be on the sun to recharge the batteries back to a full state of charge.

Michael Werner: Um, we felt that we could continue operating through the end of 2020 and probably further beyond that with gradually decreasing efficiency due to the e- effects Joseph was talking about. But there are no cliffs coming up. [00:26:00] But what happened was that in 2016 NASA held a periodic review of funding for what are called missions in extended, uh, phase, which we were along with other notable missions, which were all doing exciting astrophysics. And although we got a very high mark for our scientific work, when they, this panel, ranked the missions that they were evaluating, we came down at the- at the bottom largely because of the cost.

In response to that, NASA chose to terminate Spitzer in 2018. Then we got a year extension because the James Webb Space Telescope slipped, and there was a desire to have some continuity of the observations. But beyond that, the funding wasn't available.

Mat Kaplan: I get it.

Michael Werner: So the- the ... I don't want to minimize the importance of the engineering challenges. But as Joseph said, we've always overcome them. And we felt we could continue to do that for 12 months and perhaps even beyond that.

Mat Kaplan: My guests and I will be back with more about the legacy of the Spitzer [00:27:00] Space Telescope in a minute. This week's episode of Planetary Radio is brought to you by Amazon Prime Video's The Expanse: Season Four. And you folks know what a fan I am of The Expanse. I was one of those who was bitterly disappointed after Sci-Fi dropped the critically acclaimed show three seasons in. I and others rallied to bring it back, and Jeff Bezos swept in to save the day. Amazon Prime Video purchased the rights, and season four is streaming now. It follows the crew of the Rocinante on a mission to explore new worlds beyond the Ring Gate.

Humanity has been given access to thousands of Earth-like planets, which has created a land rush and further tensions among the opposing nations of Earth, Mars, and the Belt. The first of these exoplanets is rich with natural resources, but also marked by the ruins of a long dead alien civilization. Or are they? While [00:28:00] Earthers, Martians, and Belters maneuver to colonize the planet and its natural resources, these early explorers don't understand this new world and are unaware of the larger dangers that await them. It's a hell of a ride. Episodes are now streaming on Amazon Prime Video.

Back to astronomer and Spitzer Science Center Manager Sean Carey, Spitzer Space Telescope Project Manager Joseph Hunt, and longtime Spitzer Project Scientist Mike Werner. As project scientist, I wanted to get your thoughts about this discovery of the TRAPPIST-1 worlds, and- and what after discovering them Spitzer was able to tell us about them.

Michael Werner: Well, it's quite extraordinary. We- we- we disambiguated, I guess you could say. The ground-based observations had- had found several of these exoplanets. But because there are seven planets orbiting the same star, they all transit in front of it. At various times you'd have one, two, three, or four planets all there at the same time, planets coming in, planets leaving. And it was really very [00:29:00] complicated. So with Spitzer, because we were able to observe it basically for 20 days consecutively, we were able to disambiguate this and sort it out, tease it apart, and identified that in fact that there were seven separate planets. Previous to that there were crazy ideas about planets with moons and-

Mat Kaplan: Ah-

Michael Werner: ... lord knows what.

Mat Kaplan: Yeah.

Michael Werner: But that was only the start, because the second 500 hours that you talk about, and Sean- Sean knows more about this than I do, so I'll punt it over to him, was used to make very precise measurements of the times at which these transits occur. If there's only one planet orbiting the star, the transit will reoccur regularly at a time set by the orbital period of the planet. However, as Sean is about to explain, when you have seven planets orbiting the star, there are interesting effects which allow you to infer the mass of the planets. You know the size from the [00:30:00] amount of light the planet blocks, and that tells you the density and the composition.

Sean Carey: Yeah.

Mat Kaplan: Sean, not the three-body problem, the eight-body problem if you include the star. [laughs]

Sean Carey: That's- that- that's- that's right, uh, Matt and Mike. And so- and the interesting thing about the TRAPPIST system is the planets are all fairly closely packed, so their mutual gravitational interactions are rather significant. And they're also in this, uh, set of orbits called resonance orbits. So for every three orbits of one planet, another planet will make five planets in the same time. So you keep seeing a reoccurring arrangement of the planets. If you're like looking down at the TRAPPIST system, every 42 days or so you'd see 'em all roughly in about the same place. And what that ends up doing is getting really significant changes in the amount of time it takes for them to travel around, make an orbit around, their star, anywhere from seconds to minutes over a period of time. And that's actually what we were able to measure with Spitzer using that extra 500 hours.

I'll say, when we were planning the observations, one of the [00:31:00] things we did to maximize our- our bang for the buck was to look for times when we would see multiple planets transiting over a narrow window of a few hours. So if you could get like three planets transiting over a six-hour period, that was better than spending six hours to do one transit or two transits. So we really kinda maximized our efficiency on that.

One of the other things too I think you asked at the beginning was how much of a challenge was it for Spitzer to stare at-

Mat Kaplan: Yeah.

Sean Carey: ... TRAPPIST-1 for 20 days. And the- the answer is not much actually-

Mat Kaplan: Huh.

Sean Carey: ... because it's one of the side benefits of the orbit that Spitzer has in its Earth-trailing orbit is that any position on the sky you can look at for a minimum 40 days continuously, only stopping to do some space craft, uh, you know, engineering things like dumping momentum from the reaction wheels, and of course down linking the data, which we do any time we're getting close to filling the mass memory card, so it depends on the amount of data you take, anywhere between 12 hours in the cryogenic mission where we're taking lots of little bits of data fast and furious [00:32:00] to one to three days, you know, uh, towards the end of the mission. So it really, really depended. But that was just a benefit of being not orbiting around the Earth where you're getting occluded by the Earth. You know, you couldn't see through the Earth. Right? So and I think Hubble can see any patch of sky for 40 minutes at a time.

Mat Kaplan: Mm-hmm [affirmative].

Sean Carey: But if you put something in an Earth-trailing orbit or in the second Lagrange point you can stare at a position for a much longer period of time. [crosstalk 00:32:25]-

Michael Werner: The- the impact of the TRAPPIST discovery was colossal. I mean, not only were we above the fold in the New York Times, which is kind of the-

Mat Kaplan: [laughing]

Michael Werner: ... the crème de la crème for science, uh, public affairs, but we had an incredible number of hits on various websites and web features and news conferences and publications. And something like three billion ind ... n- not independent, um, web searches over the couple years, uh, during which this was such exciting news. And even now, it's ... if you stop to think about how it could've [00:33:00] happened, it's really quite unbelievable and extremely fortunate, of course. We only can see this phenomenon because we lie ... The orbit is edge on as we look at it, so-

Mat Kaplan: Yeah, we're in the right plane.

Michael Werner: So the fact that we're in the right plane and the fact that those seven little planets are all in the same plane to within better than a degree their orbit is really quite remarkable. So there's a lot, uh, I think Sean intimated this a lot that the TRAPPIST system can teach us about the evolution and dynamics of planetary systems. And I think you're gonna hear a lot more about it in coming years.

Mat Kaplan: Including our own, obviously, our own solar system.

Michael Werner: Quite likely, yes.

Mat Kaplan: I can tell you, we were pretty excited here when this stuff started coming out, and- and still are. You still hear all the time in the public media, in the general public media, about the TRAPPIST-1 worlds. It's held up as this example of, "Look, look, there are other worlds like ours and they're probably everywhere." We could talk for the next hour just about [00:34:00] TRAPPIST-1, but that would not be fair to all of the other [laughs] great science that Spitzer was able to accomplish. And we'll start relatively close by and work our way out through the universe. [crosstalk 00:34:12]-

Michael Werner: Before- before we go there, I think-

Mat Kaplan: Yeah.

Michael Werner: I'm not sure any of us mentioned the- the fact that at least three of the TRAPPIST planets are in what's called the habitable zone.

Mat Kaplan: Yes, the Goldilocks.

Michael Werner: The- the Goldilocks Zone where the temperature is just right, where water could be liquid on their surfaces. And that's really an important part of the whole story, so I didn't want to let that ... I'm- I'm all for going to the outer regions of the universe, but-

Mat Kaplan: [laughing]

Michael Werner: ... but we shouldn't let that important fact go unmentioned.

Mat Kaplan: Yeah.

Sean Carey: But- but- but we should also caution the listeners that just because they could have the right surface temperature to have water, that does not mean that they're guaranteed or do have water.

Mat Kaplan: Okay.

Sean Carey: And we'll only know in the future. In the future we'll be able to tell something about the atmospheric composition-

Michael Werner: Right.

Sean Carey: ... of the TRAPPIST planets, but maybe even the details of that might be hard or might be something that's in the little bit [00:35:00] more distant future than the next couple years.

Michael Werner: But- but going even further out on a limb, of course, the presence of water is thought to be necessary, if not sufficient ... by no means sufficient for the formation of life as- as we understand, uh-

Sean Carey: Sure.

Michael Werner: ... here- here on Earth.

Mat Kaplan: I'm not the careful scientist or engineers that you guys are, so I, as a statement of faith, I have faith. And, uh, after all, we're the Planetary Society, so we're not gonna ignore those little, round, rocky things. Another one of those, much smaller, was, uh, comet Tempel 1, which I did not realize until I started researching this that Spitzer had a pretty important role to play in the Deep Impact mission, which attracted so much attention around the world. We had hundreds. I think we had about 1,000 people at a nearby auditorium during the impact, all of us watching on a big screen as, uh- as we tracked it down to-

Michael Werner: Mm-hmm [affirmative].

Mat Kaplan: ... it making that big hole in the comet. But then you folks [00:36:00] started to look at the result of-

Michael Werner: Right.

Mat Kaplan: ... of that impact-

Michael Werner: Yeah.

Mat Kaplan: ... and found some interesting stuff.

Michael Werner: Absolutely. That- that was Spitzer's greatest hit.

Mat Kaplan: [laughs]

Michael Werner: That's certainly Spitzer's most, in my judgment, significant result in our own solar system. Because when that, uh, projectile hit the comet, it burrowed beneath the crusty surface of the comet and unearthed some of the primordial material which had been there for probably 4.5 billion years. And when the sun shined, or shown, on that primordial material it heated it up so we could observe it with Spitzer. And we were very well, fortuitously, extremely well-positioned to take those spectra. The process lasted for just maybe a day and a half, and then eventually that material dissipated. We were in the right spot at the right time.

We- we looked at the composition of- of those dusty particles that were unearthed from the, uh, sub-surface region of the comment. They included minerals which are well known here on Earth, [00:37:00] silicates, sulfides, perhaps even some water. They suggested to us that as this comet formed it actually incorporated material which had been at various distances from the sun in the early solar system. So you think of the comet as originating and living in the deep outer reaches of the solar system. But it appears to be the case that as it was formed, material was maybe being mixed radially outward and material that had formed at a variety of distances from the sun was eventually incorporated into this cometary nucleus.

And the other really, really important thing is that it established connections between our own solar system and the extra solar systems that we're talking about. So if you look at the composition of the material, sub-surface material, from comet Tempel 1, it's a dead ringer for material that's been seen in orbit around stars which also host exoplanets. [00:38:00] And so there's a connection between our own solar system and exoplanetary systems that Spitzer has made in many cases, and the Tempel 1 example is probably the most striking of those.

Mat Kaplan: We'll go out a little bit further, Saturn. You, folks, or Spitzer, the team, found another ring, an unexpected ring and a mammoth ring. Sean?

Sean Carey: But it's- but it's a very diffuse ring too, so it's- it's a- a very cool ring that only shines in the infrared. I forget the distance now, Mike. It's like-

Michael Werner: About 100 Saturn radii.

Sean Carey: 100 Saturn radii. So it's really far out. It's much more tenuous than the rings we see in the optical and have been visited by, uh, you know, the various things that have gone to Saturn. It's- it's interesting and probably indicates that other giant planets have similar types of rings around them, but probably even more tenuous so we're not able to see them in Jupiter, for instance. And ... But it probably also says that for giant planets in [00:39:00] other systems you have these large, very faint dust rings around them as well.

Mat Kaplan: And we're back to dust-

Michael Werner: Right, exactly.

Mat Kaplan: ... which is gonna come up yet again-

Michael Werner: Yeah.

Mat Kaplan: ... uh, as- as we head even further into this. We talked about TRAPPIST-1. It's almost a next door neighbor, 40 light years. Right? Let's go considerably further out. Uh, you're looking at a- a solar system where you are pretty sure you saw the remnants of two asteroids collided. That happened 1,200 light years from Earth, uh, which is mind-boggling to me, first of all.

But, you know, talk about the- the, first of all, the science of that, the fact that these must've been pretty big rocks. Right?

Michael Werner: Mm-hmm [affirmative].

Mat Kaplan: And put out a lot of dust.

Michael Werner: Right, right.

Sean Carey: So in- in general, actually there's- there's a couple of systems where we have seen evidence of a- a- a burst of dust production due to planetesimals or asteroids colliding. Basically what [00:40:00] happens is if you get rocks smashing in a some- some solar system, they grind each other up, and you produce a lot of dust. And it's gonna be hot due to the fact that these things are smacking together pretty high speed. And it ends up there's like a characteristic temperature for that because if the dust ... that dust that's still there and hasn't melted is about 1,500 degrees kelvin or thereabouts depending on its composition. And that's just right in the kinda the sweet spot to see in the shortest wavelength bands for Spitzer. And so this is one thing that probably was pretty commonplace in our solar system at the beginning of it, this period of- of late heavy bombardment. We probably had a lot of these types of collisions.

And if you were an observer 40 or 1,000 light years away observing our solar system at about a billion years or less, you would've seen these pop offs every now and then, and you'd see a burst, and then you'd see it decay away over a time period of months to years. And then maybe you'd see another burst again. So that's the kind of thing that's seen in several- several [00:41:00] systems now with Spitzer. And- and so in a sense, we are, we think, looking at the past of our own solar system.

Michael Werner: Right.

Sean Carey: Yeah. I- I think it is. These are good analogs for what happened previously in our- in our solar system. Yes.

Michael Werner: Another example of the way Spitzer is establishing connections between our solar system and the exoplanetary systems, not just their physical properties, but the processes that have occurred to drive their evolution, it's actually quite interesting. There are various degrees of this kind of variability that we've seen, but some of it is quite violent, and it's thought to mirror a period in the very early solar ... revolution of our own solar system where we had what are called oligarchs, you know, 10 big planets in space where there's only room for two or three. And things like the moon being b- blown off the surface of the Earth or driven off by a collision-

Sean Carey: Yeah.

Michael Werner: ... is thought to be consequence of the type of impact that Sean described. We can [00:42:00] see in exoplanetary systems by variability in the amount of dust that's- that's orbiting them.

Mat Kaplan: Joseph, as we start to talk about looking at these events taking place, pretty far away. I mean, you've looked at things far, far, much farther away than this. How does that compare with pointing the telescope at something that's happening 40 light years away or even within our own solar system?

Joseph Hunt: Pointing a telescope, uh, to me, uh, that's a total different challenge that kinda lays within these guys, the science guys here. Right? Uh, because we have this distributed operations. Down on campus at Caltech we have our science center. Typically on my end we deal more with the navigation teams and the spacecraft teams that makes all of this happen. Right? So we get observation of some event that they want to observe, and it's packaged and put into a set of logical ones and zeroes that we send up to the vehicle, spacecraft, to take [00:43:00] observation. Uh, we have those communication, uh, sessions that we get information back.

But, uh, the exciting part on our end is to see when the data has actually been processed or deduced to see the science return. Right? A lot of time, uh, you're busy doing the science planning and doing all the operational work, uh, because we keep a typical cadence with the spacecraft of about a seven-day sequencing process, meaning that we load up a set of instructions to it to tell it what to observe for about seven days. And, uh, a product to- to tell it where the Earth is at and when to come back and communicate over that time period. So we're so busy running that process over and over, every once in a while Sean or Mike will do one of their press release. We start to actually get to see-

Mat Kaplan: [laughs]

Joseph Hunt: ... you know-

Mat Kaplan: Yeah.

Joseph Hunt: ... the results of some of this great pointing. It's so rewarding, right, for the folks that's on the mission to [00:44:00] actually have that opportunity seeing something that you was a part of in the news, right, and sharing it with kids or the family members. Uh, we do an excellent job with outreach on Spitzer in several different ways-

Mat Kaplan: Yeah.

Joseph Hunt: Right? So you- you get these things out not just throughout the local community, but, you know, throughout the world as far as what's going on with this observatory. So when you talk about pointing, uh, yes, there's a lot of pointing that's going on with this observatory. But it's a huge process of getting that precise pointing.

Mat Kaplan: Maybe we'll have time to get to those.

Sean Carey: So- so Mat, Mat, Joseph's being kinda modest though-

Mat Kaplan: [laughs]

Sean Carey: ... because there's- there's times where the science asks the project to do things on a very rapid response because we see something interesting-

Joseph Hunt: Mm-hmm [affirmative].

Sean Carey: And then then respond always very quickly. And it's a challenge because you don't want to respond too quickly and make a mistake and then break something. Like you don't want to break Spitzer, right? And one particular example I can think of, um, reasonably recently where we had to make some rapid changes, and it was for a target actually we didn't [00:45:00] quite know where it was, which was ʻOumuamua, because it was-

Mat Kaplan: Oh, yeah, sure.

Sean Carey: ... coming in the solar system. So Spitzer looked at ʻOumuamua.

Mat Kaplan: Let's remind everybody. This is the- the first of the- the ... We're sure there have been many before this, but the first object coming from outside the solar system that we were actually able to say, "Yep, this one wasn't born here."

Sean Carey: Right. So it was really interesting. And one of the problems is when we were first thinking of observing with the science team, and Mike was involved in this, is that we didn't know exactly where it was because they were trying to refine its orbit, first of all, to confirm it really was a visitor from outside the solar system, and then also just to try to be able to track it down, because it was moving very quickly, and it's on this very odd orbit. And the ops teams had to respond very quickly to these changes. "Oh, well, no, we actually think ... " You know, one day it's like, "Oh, we know where it is."

Mat Kaplan: [laughs]

Sean Carey: And the next day, "Oh, we just took some more data, and it's slightly ... " But those differences made a difference because otherwise we wouldn't have been able to point at where we thought ʻOumuamua was. Now, it would've been really interesting if we actually could've shown you an image of [00:46:00] ʻOumuamua. But basically Spitzer didn't see it, which, uh, is our best non-detection, I think.

Mat Kaplan: [laughs]

Sean Carey: Because what it did is it told us that ʻOumuamua was smaller than it could've been-

Mat Kaplan: Ah.

Sean Carey: And also was- is- is dark. It was shinier than you might've expected for something that was traveling through interstellar space. And I think the best current understanding for that as it went into the system and was heated up by the sun, it started to resurface itself. So you got some- some of the, uh, activity encoded it over with a frost mantle probably of- of carbon monoxide or something like that. So it was a little bit shinier than what we would've expected from a- a hunk of- of something not very active being outside the solar system and just being bombarded by radiation and kind of getting darkened by that. So even though we couldn't see it with Spitzer, the ops teams did a great job making sure we could've seen it if it was bright enough in the infrared. We're able to say something pretty fundamental about its size and its albedo or how- how shiny it is.

Mat Kaplan: Yeah. [00:47:00] Even a null result is a result.

Sean Carey: Sometimes it's a really good one.

Mat Kaplan: Yeah. Let's push out even further into the universe. Somebody tell me what these starburst galaxies are and what you were able to discover. Mike.

Michael Werner: Right. Well, a starburst galaxy is a galaxy which is just that, undergoing a gigantic burst of star formation. It may have illuminosity which is 10 to 100 times the illuminosity of our own galaxy the Milky Way. Most of that radiation comes to us in the infrared because the stars are forming in a dense cloud of dust and gas. Their energy, as it's liberated by the young and forming stars, is absorbed by this dust and gas and being radiated in the infrared. Now, in the local universe, galaxies like this are quite rare. But if we look back, uh, about 10 billion years ago, which Spitzer has done, we see that many galaxies, galaxies which might now be like our own, [00:48:00] sort of just perking along, were undergoing this star formation phase back at that epoch. And because of that, Spitzer has been able to show the history of star formation in the gala- in the universe, the rate at which stars were forming was much higher 10, 11 billion years ago than it is now.

Mat Kaplan: Mm-hmm [affirmative].

Michael Werner: So much so that that era is referred to now as- as cosmic high noon.

Mat Kaplan: [laughs]

Michael Werner: Because if you went out, the sky would be bright and things would be going off, and it would be really, really exciting.

Mat Kaplan: Wow.

Michael Werner: And now they talk about us living in cosmic dusk, I guess, is ... Not- not ... Very interesting, but not quite as dramatic as was cosmic high noon.

Mat Kaplan: Good to know we have a few good billion years left out of the Milky Way.

Michael Werner: Exactly. Right. Right.

Mat Kaplan: Yeah. Right.

Michael Werner: And so these galaxies have ingressed for the [Milla 00:48:49] Spitzer and other infrared missions. They were first identified by IRAS, which was a predecessor mission, and have been studied not only by Spitzer but by the European Space [00:49:00] Agency Herschel mission-

Mat Kaplan: Mm-hmm [affirmative].

Michael Werner: ... which had a JPL component, and eventually will be studied by the James Webb Space Telescope.

Mat Kaplan: Let's keep pushing out there, maybe about as far as we can push with instruments like Spitzer. And it makes me think of how Spitzer, uh, did great work on its own but also did great work in partnership with other great instruments, both on the surface of the Earth and out there, of course, its sister telescope, the Hubble Space Telescope. And I'm thinking of an image that's way out there, or galaxy that's way, way out there. You know where I'm going, Sean?

Sean Carey: Yeah. So you're talking about the galaxy which is at a- a red shift, which is a way astronomers measure distance and lookback time, because it's something we can measure actually, which is the- the wavelength of how the light gets shifted back due to the expansion of the universe. So the visible light gets changed so that it's now ... it's stretched out essentially as it's traveling between the galaxy when it was emitting the light [00:50:00] and us now. So by the time we see it, the universe has expanded so that light actually, the wavelength stretches out and we see it in the infrared. So visible light, that's how the red shift name is coined is the light gets progressively redder as you look further back in time to more distant objects.

Mat Kaplan: If this was equivalent to, uh, a whistle on a train going past us, that whistle by now would be really low [crosstalk 00:50:23]-

Sean Carey: It's really low. In fact- in fact, since it's infrared and we can't see in the infrared with our own eyes, the analog would be- would be beyond the range of human hearing it would be so low.

Mat Kaplan: [laughs]

Sean Carey: So, you know, maybe like a dog would be able to hear it, but we wouldn't be able to hear it.

Mat Kaplan: [laughs]

Sean Carey: Uh, and- and so that ... but that's done in conjunction with the Hubble Space Telescope because what you're looking for is the shortest wavelength light that's emitted by the galaxy but isn't absorbed by the- the as, the- the hydrogen in the galaxy, so a- a wavelength of 912 angstroms, 'cause light shorter than a wavelength than that does not ... it gets absorbed by the galaxy so you never see it even if the stars are emitting it. So that's the- the Lyman Limit. [00:51:00] And what you can see is actually as the light gets red shift, that ultraviolet light gets red shifted into the visible light now, as things go further and fur ... we look further and further back in time, Hubble will see it at longer and longer wavelengths, and it won't see the shorter wavelengths so it'll say okay. And then from that cutoff you can figure out how back you're looking in terms of the galaxy.

So Hubble gives you the first part of the equation, but wi- with a caveat because you can see that break, and you could assign a red shift to it. But the problem is maybe you're just looking at something that's really dusty to begin with and is really nearby. So that's why you need the Spitzer data to say, "Okay, no, it's not really dusty," because it would have a different slope to the rest of the- the light curve at the ... you'd see different amounts of white at the longer wavelengths. So you're able with a combination of Hubble and Spitzer, but mostly the Hubble data, to get the red shift.

And then what the Spitzer data tells you, because now all that light from the stars, the normal stars you see, is shifted into the infrared. It [00:52:00] tells you how many stars there are. So it tells you the amount of stars in there. It measures the visible mass of the galaxy. And it also tells you how much, as Mike was talking about, how stars are forming in the galaxy at that epoch. So this [inaudible 00:52:12] galaxy already have stars in it 400 years after the Big Bang and was actively forming stars. What it's telling us is that the epoch of star formation was really early in the universe. Right? So it's gonna be very interesting to look with other telescopes to see if we can kinda see when that first epoch of stars actually occurred.

Mat Kaplan: Wow. Some of my favorite images, astronomical images, are these composites where you see all in one image, and then sometimes pulled apart. You get visible light from Hubble. You get infrared from Spitzer. You maybe get x-ray from Chandra. They tend to be, I mean, not even considering the great science, they're just beautiful images. The fact that you can combine images from instruments that [00:53:00] are looking to completely different parts of the spectrum-

Michael Werner: Yeah.

Mat Kaplan: ... and end up with something gorgeous.

Michael Werner: Couple of comments there, Mat. First of all, one of the real surprises for me of the Spitzer mission overall has been the quality of the images that we've produced. That's attributed to a lot of things, but in particular we had a very good staff at the Spitzer Science Center of in some cases astronomer artists who could really not only produce the image or produce an artist, uh, conception, but do it with an eye to the science so that it was scientifically accurate as well as being, uh, attractive, uh, to look at and generally a color table was chosen. In the infrared image, none of the radiation that goes into that image, if it's a composite of several infrared bands, is visible to the eye. But we render it as an image so we can look at it, and the way that the color tables are selected, different wavelengths-

Mat Kaplan: Yeah.

Michael Werner: ... corresponding to different colors, make it easy to- to [00:54:00] infer what's going on by looking at these wonderful images.

Mat Kaplan: 'Cause there- there's false color here.

Michael Werner: Yeah, exactly.

Mat Kaplan: Except maybe for the Hubble, right?

Michael Werner: Right.

Mat Kaplan: Yeah.

Michael Werner: And as far as the composites go, it just exemplifies, in addition to being spectacular to look at, what's now well understood, partly as a result of the great observatory, so with Spitzer is a member, and more recently because of the emphasis on multi-messenger astronomies it's called, that we really need the full range- wavelengths of information across the entire electromagnetic spectrum. And we need to corral all of that and pull it together in order to fully understand complicated astrophysical systems such as galaxies and supernova explosions and other intriguing, uh, citizens of the universe.

Mat Kaplan: I'm also amazed that Spitzer was busy doing science right up to the end. You- you didn't go out with a bang. You went out with a decommissioning that was a fairly quiet event. But, uh, you did [00:55:00] go out with a bang because I got, six days before the end of mission there were two press releases. On January 24th there was this report about this very hot world, this super heated exoplanet. And I assume that because of when that press release came out that this was data that came very near the end of the mission. Sean?

Sean Carey: Yeah, that's right. So, um, that data actually was pretty current. There was an ongoing campaign I think through the last year to take the Kelt-9b observations. Usually it takes about a year for a science result to get through the refereeing process and in a publication. So- so there's always a lag while astronomers check their facts and figures, and then it's reviewed by peers who aren't involved in it to make sure that they got the science right. Um, but it's- it's pretty current data. And there's- I think we'll probably have more press releases after the fact-

Mat Kaplan: Sure.

Sean Carey: ... as well, because the science, like you said, was still going to the end. So yeah, this ... I mean, this is a planet that is hotter than many [00:56:00] stars. It's just got an overheated atmosphere. Because of what you can think of is it's trapping the stellar radiation. So it's one of these hot Jupiter planets that's in very close to its star, so it's naturally getting, a- a- absorbing a lot of light from the star. And then its atmosphere, so this one has an atmosphere because this is the only way to explain, is trapping the radiation so that it heats up. And then it's going to emit more in the infrared.

And of course the way Spitzer sees the infrared radiation from the planet, one of these transiting planets, is by the lack of it. Usually what we do is we talk about when the planet passes in front of the star blocks out a little bit of the star light. And from that you can measure the size of the planet relative the star. In this case, if the planet is- is warm enough that it emits bright- brightly in the infrared, when it goes behind the star you lose the emission from the planet.

Mat Kaplan: Ah, okay.

Sean Carey: So essentially since it's already transiting-

Mat Kaplan: [laughs] The sun is transiting the planet.

Sean Carey: That's exactly right. Yeah.

Mat Kaplan: [laughs]

Sean Carey: So it's called a sec- a secondary eclipse is what an astronomer would call it. So you're eclipsing the planet by [00:57:00] the star in this case.

Mat Kaplan: Interesting.

Sean Carey: And because you already know the size of the planet relative to the star, and usually we know the size of the star, you can tell since you know the amount of light coming from the planet you can say what the temperature of the planet is.

Mat Kaplan: Absolutely fascinating. I'll- I'll get to that second press release in a moment. As earlier space telescopes paved the way for Spitzer, Spitzer has, I believe, paved the way for what is to come. We've talked about the James Webb Space Telescope. It's come up a couple of times. If we are lucky, fingers crossed, next year it'll get out there and, God and the universe willing, unfold the way it should and- and build on what Spitzer has done.

Then there's WFIRST even farther down the line. From an engineering sense, Joseph, has Spitzer ... I mean, do you have James Webb Space Telescope people coming to you and saying, "Okay, we're- we're wondering how best to approach this engineering challenge." Does that ever come up?

Joseph Hunt: Not James Webb in [00:58:00] particular. But, uh, remember, at JPL we have several missions going on. The Mars mission, uh-

Mat Kaplan: Sure.

Joseph Hunt: The Juno mission. There's several missions that kinda operate on the same ground, uh, principles and some of the same ground platforms. And, uh, when you say transitioning engineering, I think Spitzer has been very efficient, uh, in many of the different applications of the science collecting. And being efficient like this, we have came up to with, uh, ways of refining the engineering processes, right, and passing on some of this information to- to other missions.

Mat Kaplan: 'Cause that's a lot of it, right? It's- it's not all hardware; it's process, a lot of it.

Joseph Hunt: Oh, absolutely it's process. And one thing we kinda lose a little bit that I want to make sure that we clear up is when we talk about Spitzer and engineering, and I think Mike always, um, is, uh, acknowledging, uh, our engineering support teams, it was built by [00:59:00] Lockheed.

Mat Kaplan: Yeah.

Joseph Hunt: Right? But the Lockheed Martin ... the Lockheed section that built the spacecraft, and the Lockheed component that operated it was totally different. Right? So you would think when we talk about engineering efficiency that the folks that built it would've had the primary most experience with it to do all of this, uh, additional unique engineering. But in this case, it was a real transfer of knowledge base to another whole division of Lockheed. Uh, they did maintain a level of reach back. When I say reach back, the- they could go back and consult the folks that built it. But once it was hand off, and once this division of Lockheed understood how to operate it, they were the primary folks that we interface with. And working with them, there was several processes that was made more efficient. And because this Lockheed division [01:00:00] share other mission operations, uh, with other JPL missions, they were able- able to transfer the knowledge.

Mat Kaplan: So it does pay off.

Joseph Hunt: It absolutely pays off.

Mat Kaplan: I mean, you- you build on each other.

Joseph Hunt: Absolutely.

Mat Kaplan: Yeah.

Michael Werner: And there was one specific technical area where Spitzer really broke ground for JW, and that is in the use of radiative cooling. I mentioned earlier that we were-

Mat Kaplan: I thought of it earlier be-

Michael Werner: ... relying on radiative cooling-

Mat Kaplan: Yeah.

Michael Werner: ... to keep us cold, particularly for the last 10+ years since we ran out of helium. And James Webb is relying on radiative cooling to achieve the operating temperatures it needs for the basic, uh- um [crosstalk 01:00:37]-

Mat Kaplan: Yeah, it has no cryogenic [crosstalk 01:00:40]-

Michael Werner: It has cryogenics, but only for the longest wavelength instrument.

Mat Kaplan: Ah, okay.

Michael Werner: And I'm sure that the confidence with which they can make those projections, and the degree of risk inherent in their use of radiative cooling has been dramatically decreased by the success of Spitzer, Spitzer's radiative cooling.

Mat Kaplan: Sean, you touched on [01:01:00] this a little bit earlier. Can you talk a little bit more about how the science Spitzer has delivered is going to be built on has sort of pointed the way for JWST and maybe WFIRST farther down the line?

Sean Carey: Oh yeah. Act- actually both James Webb and WFIRST. So I- I mean Spitzer's a- has been a pathfinder in a- in a lot of regards. I mean, and primarily for the exoplanets, we know- know- we now know that, uh, exoplanets have atmospheres, and those can be studied in greater deal- detail with James Webb. Uh, both the, um, terrestrial-like ones around TRAPPIST, but a- a smaller set of those because they're still hard targets to look at. Webb will also be able to tell us a lot about the atmospheres of planets which are larger, the hot Jupiters, which are important because these are strange planets in that we don't see any hot Jupiters in our own solar system. And of course planetary science before the discovery of them didn't- really didn't consider those planets as existing.

But they're there, and we should understand them better because it's a- it's a mode of planetary formation [01:02:00] in other systems, so it's telling us something about the planetary formation process and about atmospheres in planets in general. So, you know, you think if Jupiter moved closer to the sun it would have a very different atmosphere, and those are the kinds of atmospheres that those planets would have. Regarding the- the very distant universe, you know, Webb is gonna be able to look even further back in time than the combination of HST and Spitzer, and that'll tell us very profound things. Instead of being able to do the red shifts with broad bands of light they'll be able to break the light of those galaxies into their constituent colors on a much finer scale, do spectroscopy with those. So we'll get much more detailed information about the distances to the galaxies, the masses, and kind of the star formation history of those galaxies very early on. So it's gonna tell us something profound about the mass assembly in the very early universe, which of course pertains to the structure of the universe as we see it now.

Complementary, WFIRST is going to give us a [01:03:00] very broad view in astronomy-

Mat Kaplan: Literally. 'Cause it's wide angle.

Sean Carey: Literally, right, because, yeah, it's wide angle. It has 100 times the field of view for Hubble. So it's essentially like Hubble on steroids in terms of what it'll be able to do. The spectroscopic capability's a little more limited because WFIRST is sacrificing a lot of complicated instruments for a couple of very robust instruments. The wide field camera's one of those.

And one of the things WFIRST will do, and also the European mission Euclid, is study equation of state of the universe, so basically telling us something fundamental about physics in our universe. And one of the reason- ways it does that is it looks at a bunch of galaxies at a particular red shift or red shift of two. And it's also gonna see galaxies at all different red shifts. But because WFIRST is a optical near infrared set of data, it won't necessarily know when it's found the most distant galaxies in its wild angle surveys. And for that it actually needs the Spitzer data we've already taken. The answer's in there; we just don't know it with Spitzer, and we're waiting for WFIRST to [01:04:00] unlock the key.

And this is important because while James Webb is going to be extremely powerful, it can only look at about three square degrees on the sky throughout its entire mission. And the problem with that is if you're looking at the most massive and the rarest galaxies, so the things that are generating the most massive structures early on in the universe, Webb, unless it gets very lucky, isn't going to find one of those.

Mat Kaplan: Mm-hmm [affirmative].

Sean Carey: But the combination of the Spitzer data we've already taken, and we spent more than a year actually in aggregate of Spitzer time taking data to prepare for WFIRST. And the WFIRST and Euclid surveys will- will reveal that to us, will allow us to find the most massive structures very early in the universe.

And then one of the other things Spitzer's shown is a pathfinder is- is a side light of it being so far away from the Earth. We usually think of that as a negative because it makes it harder to communicate, as Joseph said. It also gave us an entirely different line of sight to look at objects in the universe. And one of the things it allowed us to do was measure the masses of [01:05:00] planets seen by a technique called gravitational micro-lensing.

Mat Kaplan: Yeah.

Sean Carey: And this is when a star passes in front of another star. And the foreground star magnifies the light from the background star, amplifies it due to its gravitational pull.

Mat Kaplan: Yeah, thank you Einstein, right?

Sean Carey: Yeah, exactly.

Mat Kaplan: [crosstalk 01:05:15] relativity.

Sean Carey: So ... And it works. Right? I mean, it works exactly the way Einstein described it. And if there's a planet in that system with the star that's focusing the light, it'll either amplify or demagnify the light-

Mat Kaplan: Yeah.

Sean Carey: With Spitzer seeing these gravitational micro-lensing events from a different viewpoint, we're actually able to disentangle the mass of the star that's doing the lensing, the planet that's doing the lensing, and also understand how far that star is away from us. And usually when we look at the micro-lensing systems, those stars are thousands of light years away from us. And, uh, the planets that we're measuring around those stars are at a distance from the start at the snow line, so at this place where if there was water, it'd be making the [01:06:00] transition from ice to liquid water.

Mat Kaplan: Oh, literally snow.

Sean Carey: Literally snow, yeah.

Mat Kaplan: Okay.

Sean Carey: And that's just because of Einstein's equations. That's when we're most sensitive to seeing the planet is when it's at this, uh, Einstein radius away from its star, which always ends up being about the snow line.

Mat Kaplan: [laughs]

Sean Carey: Uh, it's very fortuitous. But that's something Spitzer's doing now. WFIRST is gonna spend quite a bit of its time doing a micro-lensing survey to characterize, uh, systems at and around their snow line.

Mat Kaplan: Fascinating. I want to take us right back down to Earth and start to talk a little bit more about the human side of this mission because, um, it's the humans that make it- make it all happen. And Joseph, I'm thinking of your predecessors, uh, as project manager, uh, Lisa Storrie-Lombardi, who left not long ago. She got a new job running, uh, Las Cumbres, uh, Observatory, I read, who's like you, Mike, with the mission for many, many years. Uh, anybody want to say anything about her, uh, as sort of an [01:07:00] introduction to talking about the hundreds of people who've been part of this team?

Joseph Hunt: Well- well, Lisa brings a lot of energy. Right? Uh, it's amazing watching Lisa because she worked both sides of the project. She worked on the science center side, uh, with the scientists, astronomers, sending up a lot of the databases, understanding how to process the data. Then she came over to the project manager side of it managing the overall budgets, uh, working with the various ops teams from a whole different side and still able to bring all of that together. And- and even then I think Lisa was still supporting proposals and other activities that was going on. So Lisa has been a person of energy and a really go-getter that has been a really frontrunner in a lot of the activities that Spitzer have [01:08:00] accomplished.

Mat Kaplan: Yeah. I said I wanted to use this as an introduction to talking about the team overall. Mike, you've been in it since well bef- years before the launch.

Michael Werner: Right, right.

Mat Kaplan: You've seen a lot of people come through this project.

Michael Werner: Yeah. Well, what I'd like to say, Matt, is that there's a human dimension to Spitzer which I think is very important. And it's- it's embodied in the- in the quality of the people, the care with which they worked on the mission, whether it was the design, development, operations. If you understand how Spitzer works, it's incredibly well tuned. It's just a beautiful piece of engineering, which has facilitated or enabled beautiful science. Even in this large group of people that work together there are instances of people standing out where individual contribution is very important as well.

So I view Spitzer as an example of what the human spirit is capable of accomplishing if it's properly led, motivated, [01:09:00] and empowered. And Spitzer in my judgment is really a monument to- to human capabilities and the very best that people are capable of. And I think it's well to keep that in mind. I like to say that as things get rough maybe Spitzer should be our pole star because it- it- it shows what we're capable of doing if- if- if we put our minds to it.

Mat Kaplan: As our boss the science guy likes to say around here, space brings out the best in us.

Michael Werner: Exactly.

Joseph Hunt: Oh, absolutely.

Michael Werner: [crosstalk 01:09:28].

Mat Kaplan: What are you guys up to next? Spitzer is dead. Long live Spitzer. Sean, you said we're gonna be benefiting from the data returned by this telescope for many, many years.

Sean Carey: Decades, I think.

Mat Kaplan: But- but individually, do- are you moving onto other projects? Are you still Spitzer team members?

Joseph Hunt: Well, for me in particular-

Mat Kaplan: Yeah.

Joseph Hunt: ... Spitzer has started their close out phase. And when you say they end up the mission, that's just one phase of closing the mission out. So you have the flight and the ground assets, right, that we [01:10:00] have to take care of, um, decommission the ground parts. Uh, we have to archive all of the non-science data. As Sean just mentioned, that the data will be there for years to come for the astronomers to mine. Well, there's also engineering data available because some of the environments that Spitzer have operated in when we build new missions and want to know the behavior of different opportunity components in those environments, we can go back and look at the engineering data also and see what kind of behavior you have with certain components and see whether that component is viable for the next mission or how to make changes on it to make it even better.

Mat Kaplan: Mm-hmm [affirmative].

Joseph Hunt: So then there's a final mission report where we make an assessment across the whole project as far as the spacecraft, the instruments, the ground system. And we kinda, uh, bundle that all together and make that a final closeout product that's a reference for other [01:11:00] missions to come.

Mat Kaplan: It's another way this mission is gonna live on for many, many years.

Michael Werner: Uh, on one hand I've got a major Spitzer paper that I'm finishing up. In addition, I've been fortunate enough to be involved with an upcoming JPL mission called SPHEREx. It's an explorer class mission, smaller that Spitzer, much smaller than Hubble, very, very powerful, scientifically capable of getting spectra of every point on the sky. Be an unprecedented database with many practical applications as well as a serendipitous component. And I hope that, uh, over the next few years you'll invite the- the SPHEREx principle investigator Jamie Bach or the project scientist Olivia [Adorre 01:11:42] from JPL and Caltech to tell you more about SPHEREx-

Mat Kaplan: I'd be delighted.

Michael Werner: ... which will launch in 2023 or 2024 and be tremendously exciting in its own way.

Mat Kaplan: Count on it if I'm still hosting this radio show [laughs] at that point.

Michael Werner: Excellent.

Mat Kaplan: And I hope I am. Sean.

Sean Carey: So, [01:12:00] uh, I've been very lucky working with Spitzer to have learned a lot, and so now I'm going to be using some of that expertise on a mission that's, uh, closer to home. It's, uh, the near-Earth object surveyor. So this is a- a mission that's led out of the University of Arizona by Amy Mainzer and JPL of-

Mat Kaplan: This is the follow on to [crosstalk 01:12:17] we've talked about.

Sean Carey: This is the foll ... This ... Yeah, this is the- the renaming of neocam I think is the way-

Mat Kaplan: Yeah.

Sean Carey: And- and the idea with this is to do something that I think is- is fundamentally important, uh, for- for people on the Earth, which is to try to finish the ... or at least get close to finishing the census, uh, finding all the potentially hazardous asteroids, uh, which greater than 140 meters, because those would make a really bad day on the Earth, um-

Mat Kaplan: [laughs] Right.

Joseph Hunt: Mat, before you-

Mat Kaplan: Joseph.

Joseph Hunt: Before you close, I want to go back to one thing that Mike said when we keep talking about the incredible team of people that we've had and the independent contribution, the individual contributors. And the point I'd like to make [01:13:00] there is there's a lot of times that we work with people that can be a individual contributor but sometime their ego gets ahead of them and they forget about the other people around that's helping to make things happen. Right? What- what I've experienced on Spitzer, even with the greatest contribution by any individual that's been on a mission, I've never seen any be- behavior. It's always been very embracing, very team and very friendly, very family like. So it's incredible to know people that have come up with groundbreaking technology changes to enable this great science, but they're still people.

Mat Kaplan: You're lucky. You're fortunate in that.

Sean Carey: Yeah, we are lucky.

Mat Kaplan: 'Cause-

Sean Carey: And, you know-

Mat Kaplan: Yeah.

Sean Carey: ... part of that was I think just from the top, right? Since Mike's walked out of the room we can say kind things about him. [crosstalk 01:13:54]-

Mat Kaplan: [laughs] We should-

Joseph Hunt: Yeah.

Mat Kaplan: Mike had to get to a doctor's appointment-

Sean Carey: He- he had to get to a doc-

Mat Kaplan: ... 'cause we've gone a long time.

Sean Carey: Yeah.

Joseph Hunt: Right.

Mat Kaplan: But- but you can ... now you can [01:14:00] say whatever you like.

Joseph Hunt: [laughs]

Sean Carey: You know, Mike- Mike has been I think probably if there's a singular driving force for Spitzer, it's- it's been Mike. I mean, he was, at the beginning of the mission, he was ... when it was at NASA Ames and it was brought down to JPL, he moved from the Bay Area down to work at JPL. When Spitzer was canceled I think at least two times ... In fact, there was one time it was illegal by Congress to mention the word Spitzer or [Certif 01:14:27] actually at the time. He continued to promote and coerce and- and talk people into saying, "This is what the amazing science can be done if you can just give us the opportunity."

And so, I mean, the fact that we have a mission at all is in large part due to Mike. And of course, I think par ... reason it's so successful is that, you know, we- we had somebody who's so vibrant in the science-

Joseph Hunt: Correct.

Sean Carey: ... and technically sophisticated and was able to help pull us all together as a- a really good team. So I mean, if- if we gotta give a shoutout to any- any one person I think I'd give a shoutout to Mike because-

Joseph Hunt: And I'll second that.

Sean Carey: Yeah, he's truly deserving.

Mat Kaplan: You know, I'm sorry [01:15:00] he wasn't here to hear it in person, but Mike, if you are listening to this, along with all of our other Planetary Radio listeners, uh, consider yourself much appreciated. Joseph, you mentioned in passing that the public outreach, what we call the EPO, the education and public outreach effort, in this mission has been first rate. The other, the second of those two press releases that came out on January 24th, had to do with an opportunity for everyone listening to this program right now to- to get quite literally into the center of Spitzer's data with a new virtual reality application. Are you familiar with this, Sean?

Sean Carey: Yeah, no-

Joseph Hunt: Yeah. Yeah.

Sean Carey: It's- it's really good. I mean, this is a ... We talked a little bit about the orbit of Spitzer and what you could see and what you couldn't see and how long. And the actual ... the app allows you to take virtual observations with Spitzer, steer the telescope around so you can see how close to the sun you can point-

Mat Kaplan: [laughs]

Sean Carey: ... how far away. And then there's targets so you can go observe the target. Um, I [01:16:00] think there-

Joseph Hunt: There's memory so you can see how much memory you're using as you observe the target. And it allows you to have your Earth communication session to play back the observation and then go back and observe more. I mean, it's quite a- quite a way of really getting people involved and understanding the whole operations of the Spitzer.

Mat Kaplan: It's- it's- it's Sim Spitzer but with real data.

Sean Carey: But with real data.

Joseph Hunt: Yeah, yeah.

Mat Kaplan: That's very cool. All right. We will include on this week's show page at Planetary.org/Radio, that's where you can find the, uh- this information, the link to that application, that VR application, and lots of other great information about this now completed mission, which is not really complete. Gentlemen, I'll just say once again, thank you so much. Congratulations on nearly 17 years of tremendous science from the Spitzer Space Telescope. And, uh, thank you for all you've done.

Joseph Hunt: Thank you a lot, Mat. You seem so [01:17:00] excited. You- you kinda act like-

Mat Kaplan: [laughs]

Joseph Hunt: ... maybe you were one of the team members for a minute.

Mat Kaplan: I- I wish.

Joseph Hunt: [laughing]

Mat Kaplan: I'm a fan. I'm just a fan.

Sean Carey: We- we're- we're glad. I mean, it's for the community, right? And not just the scientists, but- but the entire community, so thank you very much, Mat.

Mat Kaplan: You are most welcome. Thanks again, guys.

Boy, I bet you thought we'd never get here, but here we are. It is time for What's Up on Planetary Radio. And so we are greeted once again by the patient and wise Bruce Betts, the Chief Scientist of the Planetary Society. Welcome. It was worth the wait, right?

Bruce Betts: [laughs] Yes. Two things I'm rarely called, patient and wise.

Mat Kaplan: [laughs]

Bruce Betts: But thank you. I'll take it.

Mat Kaplan: So tell us, what's up?

Bruce Betts: Wise crackin' maybe. [laughing] What's up is Venus. I- I- I'm redundant, but it- it's so cool looking. It's really high up for Venus over in the west in the early evening. Brightest star-like object up there. Pre-dawn we got a whole planet [01:18:00] party getting underway with Mars up highest looking reddish. And then to its lower left is Jupiter looking very, very bright. You can also check out Mercury back in that evening west far below Venus. So, uh, just hopping between morning and evening planets, planets, planets.

Mat Kaplan: [laughs]

Bruce Betts: All right. We move onto This Week in Space History. Uh, 1971, Apollo 14 on the moon, which of course is [laughs] for better or worse best known for Alan Shepard hitting a golf ball.

Mat Kaplan: [laughs] I don't think that's a terrible thing to be known for. It- it might be as good as being known for giving the first haircut in space. But oh my. I don't want to spoil anything. [laughs]

Bruce Betts: I look forward to it. In 1990 this week Galileo, which was on its way to Jupiter, flew past Venus. No, they didn't get the- get their map wrong. They actually used-

Mat Kaplan: [laughs]

Bruce Betts: ... Venus' gravity. They went [01:19:00] in to go out. I always found that kind of amazing.

Mat Kaplan: You gotta be cool to be kind.

Bruce Betts: [laughs]

Mat Kaplan: I don't know- I don't know what that has to do with anything. Please go on.

Bruce Betts: [laughs] Sorry. That really tickled me. That was truly more random than my random space fact. [laughing] Moving on to Random Space Fact.

Mat Kaplan: [laughs]

Bruce Betts: I hear you've, uh, heard something about the Spitzer Space Telescope.

Mat Kaplan: Really?

Bruce Betts: Did you hear ... Yeah. Did you hear that the actual telescope part, all of the- all of the parts of the telescope except for the mirror sports, all the rest of the entire telescope made of beryllium.

Mat Kaplan: Oh.

Bruce Betts: Beryllium, which is extremely light, very strong, and, uh, has very low heat capacity and works nicely for an infrared telescope.

Mat Kaplan: Aren't the mirrors on the James Webb Space Telescope made of beryllium?

Bruce Betts: I believe they are indeed, and so is the mirror on, uh, not the coating, but the- [01:20:00] the mirror on- on Spitzer, also made of beryllium. We move onto the, uh, [laughs] the incredibly important question-

Mat Kaplan: [laughs]

Bruce Betts: ... from the trivia contest. I really am pushing the- the bounds of trivia between this question and the question I'm going to ask today. So what mission and what astronauts were involved in the first haircut in space? How'd we do?

Mat Kaplan: Well, I don't know about you, but I love these questions. These are- these are trivial ... worth the trivial pursuit is what they are.

Bruce Betts: [laughs]

Mat Kaplan: Uh, let me give you the contrarian answer from Kay Gilbert in California. She says, "It depends on how you define haircut. Technically, the first hair that was cut in space was by the Apollo 10 astronauts when they shaved their faces in May of 1969. But we don't know who went first, Cernan, Stafford, or John Young. I know. Not what you were looking for."

How about this from Courtney [Catts 01:20:59], who, [01:21:00] uh, has not won in a couple of years, Courtney out of Pennsylvania. She says, "In 1973, on the first manned mission to the Sky Lab Space Station, which was oddly enough Sky Lab Two, astronaut Paul J. Weitz received the first ever haircut in space. Who gave it to him? None other than Charles Pete Conrad."

Bruce Betts: That's correct. Uh, except for that face, uh, thing.

Mat Kaplan: [laughs]

Bruce Betts: But yeah, that's what I was looking for.

Mat Kaplan: I just think it's fascinating that, you know, Pete Conrad gave the first haircut in space after he became the third person to walk on the moon in- in Apollo 12. That's- that's- I think that's pretty entertaining. Courtney-

Bruce Betts: [laughs]

Mat Kaplan: ... we're sending you, if you want 'em, some space stickers, including the brand new Planetary Radio sticker. And you'll have to tell us what size Planetary Radio t-shirt you want. All the stuff coming from the Planetary Society store at ChopShopStore.com. Congratulations.

We got more of course. John Leindecker in Colorado, [01:22:00] he met Captain Weitz while he was a student at, uh, Penn State. He said, "He was great inspiration for me. It was a thrilling experience to meet an actual astronaut." John, wa- was his hair still perfect?

Bruce Betts: [laughs] Well, I don't know that it was perfect after Pete Conrad cut it, but-

Mat Kaplan: [laughs]

Bruce Betts: Maybe.

Mat Kaplan: Uh, Gunther [Muilde 01:22:22] in Germany. "Given that Weitz's hair wasn't exactly knee-length to begin with, the result was probably a buzz cut. Though technically it wasn't a buzz cut, but a Pete cut." [laughs]

And a poem this week, not our poet laureate, but Jean [Lowen 01:22:39] up in Washington. Joseph Kerwin sat and waited. Two bits was all he had. Just a few orbits of SL2 was really not too bad. Reading an outdated magazine from the rack in the Sky Lab while Pilot Weitz was being quaffed by fellow naut Conrad. [laughing]

Bruce Betts: Nice.

Mat Kaplan: Yeah, I thought [01:23:00] that was entertaining too. We can move on, and I've got a pretty cool prize for next time.

Bruce Betts: The Spitzer Space Telescope was named after Lyman Spitzer, an American theoretical physicist, astronomer, mountaineer. What was Lyman Spitzer's middle name?

Mat Kaplan: [laughs]

Bruce Betts: Important trivia. Go to Planetary.org/RadioContest.

Mat Kaplan: You have until the 12th, that'll be February 12th at 8:00 AM Pacific Time, to enter this time and win yourself a Planetary Radio from ChopShopStore.com, but also a copy of Michael Werner's book. Yes, Michael Werner, the long time project scientist, the only one they've had for the Spitzer Space Telescope has written More Things Than the Heavens: How Infrared Astronomy is Expanding Our View of the Universe. He wrote it with Peter Eisenhardt, a- a colleague of his at JPL, another scientist. It is getting fantastic reviews, including from Sky and Telescope [01:24:00] magazine. And it can be yours if, uh, you're chosen by Random.org and- and come up with, uh, Lyman's middle name.

Bruce Betts: All right, everybody, go out there, look up at the night sky, and think about what you would put on a space sticker. Thank you, and goodnight.

Mat Kaplan: I know you're challenging me. I don't accept the challenge. There is nothing better to put on a space sticker than Planetary Radio-

Bruce Betts: [laughs]

Mat Kaplan: ... which brings you What's Up each week with the Chief Scientist of the Planetary Society Bruce Betts.

Planetary Radio is produced by the Planetary Society in Pasadena, California. It is made possible by its radiant members. Catch the heat by joining them at planetary.org/membership. Mark Hilverda is our associate producer. Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. Ad astra.