Planetary Radio • Dec 15, 2021

JWST is ready for launch and amazing science

Please accept marketing-cookies to listen to this podcast.

Download MP3

On This Episode

Rene doyon portrait

René Doyon

Director of Mont-Mégantic Observatory and the Institute for Research on Exoplanets at the University of Montreal

Hammel heidi

Heidi Hammel

Vice President, Board of Directors of The Planetary Society; AURA Vice President for Science

Michael mcelwain portrait

Michael McElwain

JWST Observatory Project Scientist, NASA Goddard Space Flight Center

Bruce betts portrait hq library

Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

Kaplan mat headshot 0114a print

Mat Kaplan

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

The James Webb Space Telescope will begin its mission of discovery as soon as Dec. 24. René Doyon, Heidi Hammel and Mike McElwain join us for a conversation about what it may reveal from our solar system to the edge of the universe. Doyon is principal investigator for the telescope’s NIRISS imaging spectrograph, Hammel is vice president for science at the Association of University for Research in Astronomy (AURA) and McElwain of the Goddard Space Flight Center is the JWST Observatory project scientist. What do chief scientist Bruce Betts and a horse have in common? Find out in the What’s Up space trivia contest.

JWST preparing for transport
JWST preparing for transport The James Webb Space Telescope seen being prepared for transport to French Guiana for launch.Image: NASA/Chris Gunn
James Webb Space Telescope at L2
James Webb Space Telescope at L2 This artist’s concept shows the James Webb Space Telescope at a special location in space called L2 located 1.5 million kilometers (932,000 miles) from Earth. There, the Sun and Earth’s gravity balance out in a way that allows Webb to permanently keep the Sun, Earth, and Moon at its back while it observes the cosmos.Image: NASA / Adriana Manrique Gutierrez

This content is hosted by a third party (, which uses marketing cookies. Please accept marketing cookies to watch this video.

JWST Deployment Sequence Before JWST can do its job, it must first get to space and execute one of the most complex deployment sequences ever attempted. Credit: NASA's Goddard Space Flight Center

Related Links

Trivia Contest

This Week’s Question:

Who do we have to thank for suggesting the planet name “Uranus?”

This Week’s Prize:

A 2022 International Space Station wall calendar.

To submit your answer:

Complete the contest entry form at or write to us at [email protected] no later than Wednesday, December 22 at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

Galileo discovered the four “Galilean” moons of Jupiter in 1610. When was the next one discovered, and which moon was it?


The winner will be revealed next week.

Question from the Dec. 1, 2021 space trivia contest:

I’m a mythical creature and I gave my name to a class of small-body objects that orbit between Jupiter and Neptune. What am I?


Bruce Betts is a Centaur, the name given to a class of objects that orbit between Jupiter and Neptune. They appear to have characteristics of both asteroids and comets. (Get it?)


Mat Kaplan: The James Webb Space Telescope is ready for launch, and the universe, 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.

Mat Kaplan: After 20 years of development, the JWST is days away from the beginning of what scientists around the world hope will be a mission of discovery that rivals or surpasses the Hubble Space Telescope. Three key members of the telescope team will take us through what it may reveal. Rene Doyon, Heidi Hammel, and Michael McElwain will also explain why major advances in science can require major investments.

Mat Kaplan: Bruce Betts asked you what mythical creature he is. We'll go beyond the man in the myth when we answer his question during What's Up. Bruce will also tell you where to find Comet Leonard, if you hurry and you're lucky. There's a beautiful image of the recently discovered visitor from the Oort cloud at the top of the December 10 edition of the Downlink. You can also read about the total solar eclipse on December 4th. It was mostly visible only from Antarctica. It shows up as a dark spot over the South Pole in a satellite image at

Mat Kaplan: Heard about the moon hut? China's Yutu 2 rover spotted it on the far side. We're hoping for a less fuzzy view of what's probably just a bolder. Remember, extraordinary claims, extraordinary evidence.

Mat Kaplan: I have a couple of other suggestions for you. First, there's our terrific new video about night sky photography. This lazy amateur astronomer enjoyed it immensely, and I learned a lot. It features Planetary Society member Ossey James. The video and accompanying article can be found at, which is where you can also read an interview with the woman who hired me at the society more than 20 years ago.

Mat Kaplan: Charlene Anderson was the first person brought in by our founders in 1980, the first editor of our magazine, The Planetary Report, and our associate director. It's wonderful to hear from her again.

Mat Kaplan: The history of what would become the James Webb Space Telescope goes back to at least 1989. Now nearly 23 years later, the giant infrared eye is about to begin its work. As we publish this week's Plan Rad, the telescope is on top of the European Space Agency's Ariane V rocket that will send it to L2, a so-called Lagrange point at which the gravity of the sun, the Earth, and the moon are almost perfectly balanced.

Mat Kaplan: L2 is nearly four times as distant from Earth as the moon is, making it essentially unreachable, should anything go wrong, and there is plenty that could go wrong. But our guests are among those who are confident it will unfold like a beautiful origami flower, revealing its six and a half meter segmented mirror made of gold-plated beryllium and the massive five-layer sunshield that will keep the telescope cool enough to detect the most distant objects in the universe.

Mat Kaplan: Four intricate and powerful instruments will stare at the light collected by the mirror. The principal investigator for one of these is Rene Doyon, Director of the Mont-Mégantic Observatory and the Institute for Research on Exoplanets at the University of Montreal, where he is a professor of physics.

Mat Kaplan: Joining Rene and me a few days ago was Heidi Hammel, Vice President for Science at AURA, the Association of Universities for Research in Astronomy. AURA is the nonprofit consortium that manages and operates astronomical facilities, including the Hubble Space Telescope and the JWST through its Space Telescope Science Institute. Heidi is also Vice President of The Planetary Society Board of Directors.

Mat Kaplan: Michael McElwain of NASA's Goddard Space Flight Center completes our trio. Mike is the JWST observatory project scientist. Heidi, Rene, Mike, welcome to Planetary Radio on this auspicious day. Well, it's not happening today, but we are within days of this absolutely marvelous event that is going to take place, something that I know you and a lot of us out here have been waiting for for many years, the launch of the JWST. Thank you for joining us.

Mat Kaplan: Mike, I'm going to start with you. What's the current status of the telescope? We're speaking a few days before this program will be published and available across the web and on radio.

Mike McElwain: Great. Thanks, Mat. It's a pleasure to be here. We're planning for launch on December 22nd. That's at 12:20 PM, UTC, 7:20 AM in the morning, Eastern Standard Time, where I'm located, or 4:20 AM, Pacific.

Mike McElwain: Everything's looking great for launch. Webb is completed all of its tests. We've integrated with the payload adapter system that goes on top of the Ariane V launch vehicle. We filled our propelling tanks. We actually use two different types of propellant.

Mike McElwain: We moved to the final assembly building a few days ago. We're doing the final assembly with Ariane V launch vehicle. We'll do that lift on Saturday, December 11th, and we will do the final faring integration and encapsulation.

Mike McElwain: Then we actually have a mission dress rehearsal. So the team will assemble at the launch site and at the mission operations center. We will carry out a dress rehearsal. We'll test not only the personnel and the systems, but we'll do the communications and the data flows between the various nodes that participate in commissioning between the launch site, the mission operations center at the Space Telescope Science Institute in Baltimore, Maryland, and the Deep Space Network.

Mike McElwain: Thursday and Friday of next week, we will prepare the launcher for moving out to the pad on Monday. Then we'll have final health checks before our December 22nd launch.

Mat Kaplan: So by the time some people hear this, maybe that launch will already have taken place. But at this point, it's still anticipation. I'm excited. I wonder about you folks. Excited, apprehensive, hopeful, confident? How does this feel, Heidi?

Heidi Hammel: All the feels, Mat, with every emotion all wrapped up into one swirl. Anticipation. We've been working on this project for decades, some of us literally decades, and we are just so excited, but nervous. It's putting precious telescope on a big rocket and sending it into space. Rocket science is hard. I think mostly just a state of anticipation. We are just waiting now, waiting for all the last steps to occur.

Mat Kaplan: Rene, we're going to talk about your very important role in this mission, in this telescope. But I ask you the same question. Knowing that your instrument is about to reach into space as part of this telescope, how do you feel?

René Doyon: Yeah, like Heidi, I'm just absolutely thrilled. I'm really pinching myself because I've been on this project for 20 years. You get used to this thing taking some time, but now this is it. We are days away from launch. I'm just absolutely excited.

Mat Kaplan: Mike, are you going to be at the launch site in French Guiana?

Mike McElwain: Actually, I will be at the mission operation center shortly after launch. We get control of the observatory in space at the mission operation center. So that's when we'll actually start doing the commanding, we'll start the commissioning process. The first 12 and a half hours are very intense. We get communications with the telescope, we're tracking its orbit, how it released from the Ariane V.

Mike McElwain: We actually have to carry out a midcourse correction. That is an initial burn that puts us out at our orbit and L2. The timing of that burn is actually very important because it's costly in terms of propelling if we make a late burn.

Mike McElwain: And so, everyone will be working very hard at the first 12 and a half hours. Then we can relax a little bit. We have an additional burn to make, and then we'll start our deployment sequence.

Heidi Hammel: I just wanted to add for the listeners that the mission operations center is hosted at the Space Telescope Science Institute in Baltimore, Maryland, on the campus of Johns Hopkins University. The launch itself, of course, is taking place from the spaceport in French Guiana because we are launching on an Ariane V rocket provided by the European Space Agency. So we're not launching at Cape Canaveral or Kennedy, any of the usual NASA spaces.

Heidi Hammel: I will also, like Mike, be in Baltimore, near the mission ops. Although unlike Mike, I'm not going to be allowed into mission ops. I'll just be outside with the VIPs and the reporters and the other folks who are just hanger on. I'm not going to be in mission op.

Mat Kaplan: Wringing your hands, no doubt. This, of course, is an example, and we will have more, including why Rene is here. This is evidence of the international nature of this mission, of this telescope. But I'll come back to that. Mike, how long are we going to have to wait until this instrument sees first light and it begins to do the science that we're all looking forward to?

Mike McElwain: Yeah, so it takes about 30 days in order to do all the deployments. That actually happens more quickly. In about the first 14 days we do, 50 major deployments. Then we start cooling down. And so, we actually need to wait for the science instruments to reach their operational telescopes, because we use them in order to do the alignment of the telescope. And so, those instruments will be cool enough to start observations around 30 days into the mission.

Mat Kaplan: Amazing. As cold as space will be, that the requirement of doing the science that is going to be required of this infrared telescope, it's still going to take 30 days for you to reach that point. Heidi, I'll start with you for this one. Does this telescope have the potential to shock and amaze us the way the Hubble Space Telescope has for so many years?

Heidi Hammel: There's no doubt that the data we're going to get from James Webb Space Telescope will indeed amaze us. I'm not sure about the word shock. That's perhaps not a word I would use. But the capabilities that we have designed for this telescope are revolutionary.

Heidi Hammel: The sensitivity that we will have, the spatial resolution at the mid-infrared wavelengths, all of these have been designed to push us into new frontiers of astrophysics that have simply not been available to the telescopes that we currently have on the ground and in space.

Heidi Hammel: And for the listeners who mostly like the beautiful pictures of Hubble, we will have equally beautiful pictures coming from the James Webb Space Telescope as well, in addition to all the amazing science that's going to happen.

Mat Kaplan: Here's a question that I'm sure all of you have heard time and time again. Are there ways to compare the Hubble and this new space telescope, just in terms of making it clear how much more powerful this instrument is, at least at what it's designed to do?

René Doyon: Well, I can jump in on this. I mean we're talking about two orders of magnitudes in terms of sensitive improvement compared to Hubble, basically because Webb is much bigger, of course. It's 6.5 meter in diameter compared to 2.4 meter.

René Doyon: The other thing too is that even though Hubble was, with time, a greater instrument to do, a little bit of infrared, it's not really optimized. Hubble's just going around the Earth every 90 minutes and it's not in a very stable environment. With Webb, it's going to be sent 1.5 million kilometers away and always in the shadow of a very cold environment. That's what we want, to do very sensitive and precise infrared astronomy. So that's the main difference.

René Doyon: If we talk about sensitivity improvement at the mid-infrared, a long haul of five to 28 microns, the only thing we could compare with was Spitzer, an 85-centimeter. Now you're talking about essentially the improvement of million. That's a huge improvement. Things that was very faint star for Spitzer are saturating our detector with James Webb. So there's incredible improvement.

Mat Kaplan: I know that you've all also been involved, are involved, with ground-based astronomy. What will JWST do that can't be done as well by ground-based telescopes? I include in this, of course, the new class of gigantic instruments that are going to be seen first light in the next few years.

Heidi Hammel: The challenge with ground-based telescopes is that they are on the ground. Between them and outer space is Earth's atmosphere. Earth's atmosphere absorbs certain wavelengths of light, the molecules in our atmosphere, the water molecules, carbon dioxide molecules, et cetera. They absorb light and that light can never reach our ground based telescopes.

Heidi Hammel: For example, to observe in these mid-infrared wavelengths that we are so interested in with James Webb Space Telescope, we have to go to space to observe them. There are a few windows, we call them windows, where some of the mid-infrared light can make it to the surface.

Heidi Hammel: But also mid-infrared light is heat. It's warmth. Our Earth and our telescopes on Earth are warm. And so, the warmth of our telescopes overwhelms the warmth from these distant galaxies and stars. And so, the only way to make these observations is to put our telescope not only up in space above the Earth's atmosphere, but very far from the Earth with a big sunshield that's shading the telescope from Earth and the moon and the sun. By shading our telescope, we can keep it super cold and detect this light from the distant universe.

Heidi Hammel: So I don't care how big your ground-based telescope is. Give me a 30-meter telescope. I'd love that. But it can't do the science that Webb is being designed to do.

Mat Kaplan: I want to hear from each of you what you hope the JWST may reveal to us about the cosmos. I mean ranging from worlds that are relatively nearby to galaxies that stretch back to the beginning of the universe.

René Doyon: I was trained as an extragalactic astronomer. My PhD was in, in fact, spectroscopy and tracking colliding galaxies. So that's one thing that's very close to my heart in finding the very first galaxies that lit up. We think a few hundred million years after the Big Bang, that would be a fantastic discovery. All four science instruments on board Webb are designed to do just that.

René Doyon: But in 1995, my life changed. That was the very first discovery of an exoplanet. At that time, we started to dream of actually taking pictures of them. We managed to do that 10 years later. In fact, one of my quest is to basically detect an atmosphere of an exoplanet that has water on it. That's the big step.

René Doyon: We have more than 4,000 exoplanets discovered so far, a handful of them in the so-called habitable zone, these regions not too close, not too far from the star, where we can hope to detect liquid water on the surface. We have the targets and those were discovered only a few years ago. The Webb instruments will be capable of detecting the atmospheres. That's a key, a key stepping stone, towards detecting biosignatures, molecular [inaudible 00:16:19].

René Doyon: I don't want to say that Webb will do this. Nature would have to be really generous for it to do that with Webb. But it's clear that Webb will make a giant step in that direction. So that's the two thing I'd like to see. First light and water in a temperate planet.

Mat Kaplan: Mike?

Mike McElwain: Yeah. I'd like to echo what Rene was saying. I'd also like to add for the listeners that Rene was also the first person to directly detect an exoplanet. He did that with a ground-based telescope, and it was a huge discovery for which he's received multiple awards.

Mike McElwain: Like Rene, I think the early universe observations we've never been able to see there before, that was the primary motivation for building Webb initially, to go beyond the Hubble Space Telescope. Astronomers, even in the mid 1990s, knew that we needed a large infrared space telescope to observe the early universe because of the cosmological redshift.

Mike McElwain: We will be able to do that, and that's one of the first sets of observations that will be carried out in our Cycle 1 science program. We will look and see what the first luminous objects are and what they look like and how those objects then evolved into the current universe that we have today. So that's super exciting.

Mike McElwain: Also, I'm very excited about exoplanets. I study exoplanets myself. There's so much discovery, as Rene was saying, back in 1995. The first exoplanet was discovered orbiting a sunlight star. We now know of over 4,000 exoplanets orbiting other stars. Those are outside our solar system.

Mike McElwain: Webb will really be in a position to characterize these exoplanets in a way that we've never had before, with these infrared capabilities. Oftentimes, while there are many key molecules and elements and atmospheres in the infrared, so we can study their compositions and get insight into their formation mechanisms. It's just going to be a transformative new capability for exoplanets.

Mat Kaplan: Heidi, I want to hear from you too, but I've got to boast for a moment. One of the highlights in my career here doing Planetary Radio was the conversation I had with Michel Mayor, the gentleman who was part of that discovery of the first exoplanet circling ... Well, a regular star, not a pulsar in that case. Heidi, what are you looking forward to?

Heidi Hammel: Well, everything that Rene and Mike have said already, first light in the universe, first galaxies, maybe the first stars, exoplanet characterization, the evolution of galaxies over cosmic time. That's all really exciting.

Heidi Hammel: I'm a planetary astronomer, and one of the things that's amazing about Great Observatories, with capital G, capital O, Great Observatories, like Hubble and Webb is that they don't just do one thing. So in addition to the great science that you just heard Rene and Mike talk about, Webb will also be able to study objects within our own solar system. That's why I signed onto this telescope two decades ago. There was some science I really wanted to do, and I needed this telescope.

Heidi Hammel: So characterizing the surfaces of Kuiper belt objects, not only Pluto but even smaller ones. Many dozens of Kuiper belt objects will be characterized with Webb. I'm interested in the upper atmospheres of Uranus and Neptune. They have fabulous molecular signatures in the mid-infrared that Webb will be exquisitely sensitive to. So we will learn about the dynamics in the upper atmospheres.

Heidi Hammel: We will be studying Jupiter, even though it's really bright. It's going to be a challenge to observe bright objects like Jupiter and Saturn with a telescope that's designed to observe the faintest galaxies in the universe, but we have our ways, tricks and ways, of doing that. Maybe we'll figure out finally what the chromophores are on Jupiter, making the redness of the Great Red Spot.

Heidi Hammel: I could go on. There is just such a wealth of wonderful science that will be coming from James Webb Space Telescope. It's truly going to be rewriting of the textbooks in many, many different fields of astronomy and astrophysics.

Mat Kaplan: Rene, I know that you have to leave us a little bit earlier than your colleagues. So I want to ask you about your baby, the near-infrared imager and slitless spectrograph, NIRISS. How do you pronounce that?

René Doyon: Well, we call it NIRISS.

Mat Kaplan: NIRISS, okay.

René Doyon: NIRISS.

Mat Kaplan: It sounds like a remarkably powerful and versatile instrument.

René Doyon: Yeah. So a NIRISS is an instrument that ... Well, let me give you a brief overview of the instruments on board. We have NIRCam, the machine that will take images. Also, that's the machine that will align the telescope. That's a workforce capability. We have the NIRSpec, the European-based and US-built multi-object spectrograph. So that's the machine to the spectroscopy.

René Doyon: Astronomers like images, but we need also spectra. So we need to be able to disperse light. That information gives us key information about the chemical composition of the objects and also the speed, distance. In the wavelength range, we have MIRI that will do both imaging and spectroscopy at a longer wavelength.

René Doyon: Now NIRISS is an instrument very similar to NIRCam, but simpler, that will be used mostly for spectroscopy capability. In fact, that's an instrument that came a bit late in the game. It was not planned from the get-go. It was formally accepted in 2011.

René Doyon: We designed NIRISS to do one thing. Well, I talked about exoplanet atmospheres. We have an observing mode inside NIRISS that is specifically designed to look at the exoplanet atmospheres on bright stars. In fact, we will devote almost half of our guaranteed time observations to look at a wide range of exoplanet atmosphere. That's one thing.

René Doyon: The other aspect of NIRISS is that we have a mode that can do slitless spectroscopy, which is unlike NIRSpec that takes little slit to isolate the object that you want. That's the most hectic way of doing it. But a NIRSpec can observe more than maybe 200 objects at the same times, whereas for some objects like galaxy cluster that we'll look at, we can take thousands of objects in one shot.

René Doyon: So it's very complementary. So we hope that NIRISS will be able to find a high range of galaxies, very distant galaxies, and then tell NIRSpec, "Look, point your slit here. That's a high range of candidates."

René Doyon: Finally not least, on the back of NIRISS, we have the Fine Guidance Sensor, which is not a scientific camera, but nonetheless absolutely crucial. That camera is actually designed to make sure that every time when they ... Any information, NIRCam, NIRSpec, MIRI, we make sure that we correct the vibration of the telescope. This big structure will vibrate along.

René Doyon: So what we do is the camera, we pick up a star in the field of view and we measure its position sixteen time per second, and then we send that single to a steering mirror about the size of a foot, roughly. That way we keep the image very, very crisp.

René Doyon: Just to give you an idea of how accurate this camera has to operate, we can detect a movement the equivalent of the thickness of a human hair at one kilometer, or if you want, you are, Mat, in Washington, and you're blinking at me, and I can see that from New York City. It is that accurate that this camera has to operate.

René Doyon: So to me, every time I'll see a beautiful image from Webb, well, I think of this woman at Honeywell who did the software to do the guiding system. It's an incredible machine.

Mat Kaplan: What you have just described, NIRISS, FGS, these are the two major contributions to the telescope from Canada. You, of course, at the University of Montreal and other facilities there. I want to come back to the international collaborative nature of this project, which is this is such a good example of. Heidi?

Heidi Hammel: It truly is. I mean Hubble, of course, was an international collaboration as well between NASA and the European Space Agency. This project, James Webb Space Telescope, was from the get-go designed to be a strong international collaboration between NASA, the European Space Agency, and the Canadian Space Agency. You heard from Rene the crucial contributions from Canada, our Fine Guidance System and the things that we're going to use to actually track on our objects. It's absolutely crucial.

Heidi Hammel: Of course, the launch vehicle is a European contribution, as well as the NIRSpec instrument. This is going to be the very high resolution spectrometer being contributed by European Space Agency. It's going to have a really interesting mode where it uses tiny little microshutters, tiny little microshutters, allowing us to isolate different parts of the sky on which we can get our spectroscopy.

Heidi Hammel: It's really been a wonderful experience to be a part of this international collaboration, meeting with Rene at our meetings over the years, whether they're in Canada or in various places in Europe or the United States. It's been a really wonderful experience to work with all of our international partners together to make a global contribution. It's wonderful. Thank you, Rene.

René Doyon: Thank you. Oh, MIRI is also another example that was more than I believe 14 countries in Europe to actually make this instrument, but using the US detectors. So very nice collaborations all across the board.

Mat Kaplan: Mike?

Mike McElwain: Yeah. I'd like to add that not only did we partner with the Europeans and the Canadians, but the data that we'll receive from James Webb will be archived at the Space Telescope Science Institute and made publicly available to anyone in the world. And so, astronomers from all over the world will be able to analyze this data and make discoveries.

Mike McElwain: The proposal process itself can be made from anywhere in the world as well. And so, the Cycle 1 call for proposals had applications from over 44 different countries participated. And so, it's very much a global effort, and the science discovery that will make will have a global reach.

Mat Kaplan: Rene, I know we've reached the time when you're going to have to leave us, but I got one other question for you. Interesting also to hear that NIRISS, you called it a late addition to the project 10 years ago, going on 11 years ago. How did it feel? Do you remember that moment when you learned that this instrument for which you are principal investigator would be a part of-

René Doyon: Oh yeah. Look, this is my moment. I mean there's been many moments for James Webb, of course, but for me, that was ... That date, I remember vividly. June 9th, 2011 when the science working group approved our plan to reconfigure the previous instrument into NIRISS. That was such a big moment for me.

Mat Kaplan: Very exciting. Thank you for taking the time that you could this last half hour or so with us. We'll continue with Mike and Heidi. But we better let you get onto your other commitment. Thanks so much.

René Doyon: My pleasure. Thank you for having me. Just three words: Go, Webb, go. Bye bye.

Mat Kaplan: Go, Webb, go. I love it. Thank you, Rene. A very brief break now before I return with our three guests and much more about the JWST.

Bill Nye: Hi, everybody. It's Bill. 2021 has brought so many thrilling advances in space exploration. Because of you, The Planetary Society has had a big impact on key missions, like the Perseverance landing on Mars, including the microphone we've championed for years. Our extended LightSail 2 mission is helping NASA prepare three solar sail projects of its own. Now it's time to make 2022 even more successful.

Bill Nye: We've captured the world's attention, but there's so much more work to be done. When you invest in the Planetary Fund today, your donation will be matched up to $100,000 thanks to a generous member. Every dollar you give will go twice as far as we explore the worlds of our solar system and beyond, defend Earth from the impact of an asteroid or comment, and find life beyond Earth by making the search a space exploration priority. Will you help us launch into a new year? Please donate today. Visit Thank you for your generous support.

Mat Kaplan: Mike, you have been deeply involved with all of these international collaborators, as well as the people putting this telescope together. Now I said upfront we're focusing on the science in this conversation because we covered a lot of the engineering, when I visited the JWST last summer out here in Southern California. But, still, I hope you can say thing about what it was like, what it has been like, to pull together a project of this magnitude with so many different elements and so many different contributors.

Mike McElwain: Yeah. I mean I like to say that this is a major accomplishment for humanity, that we can build a telescope that enables us to see the first luminous objects in the universe, the very first objects that were formed after the Big Bang. This is just such an amazing accomplishment.

Mike McElwain: When we set out on this path, we didn't have many of the technologies that we needed to do that. And so, the engineers took our science requirements that the team had put together and transitioned them into engineering requirements and built this beautiful space telescope.

Mike McElwain: If you look at a picture of the James Webb Space Telescope, it doesn't look anything like you might expect for a space telescope. For one, the telescope is actually unbaffled. So it's just out in deep space.

Mike McElwain: That was a different design, somewhat of an innovation in that we have an orbit at L2 that's about a million miles from Earth, four times the distance of the moon, and we're able to keep that telescope in the shade for the entire mission. At any one time, we can look at about 40% of the sky. As we orbit around the Earth, we can observe anywhere at the sky.

Mike McElwain: But there were just many technological advances, new detectors, new sunshield materials, new structures that can operate at the cryogenic temperatures. Of course, all the testing that went into determining that we had the right design and workmanship of the flight system was tremendous as well. We needed to have components from all over the world come together and assemble them and test them. We did major tests at the Goddard Space Flight Center of the telescope itself and flew that down to the Johnson Space Center, where we did a hundred-day cryogenic test.

Mike McElwain: Hurricane Harvey happened to hit Houston right in the middle of that test. So that was unexpected. But we dealt with that and the team continued to carry on the test, even in those extreme weather conditions. Then we moved the telescope out to Northrop Grumman, where it met up with the sunshield and the spacecraft bus and did those final integrations and tests.

Mike McElwain: And so, it's been a tremendous effort, a lot of dedication and perseverance from the team. Everyone's just super excited to be where we are and to start this mission in space.

Mat Kaplan: Heidi, with the long history of the development of this telescope, and with things having gone pretty well in the last few years, it would maybe be easy for some people to forget a more troubled time when there were big questions about whether this telescope would be completed, whether it would receive the funding that it would need to reach this day. Those must have been tough times.

Heidi Hammel: There were some tough times. I remember 2011, when the funding for James Webb Space Telescope was zeroed out of the federal budget. That was a bit of a downer. We had to work very hard. There was actually a groundswell of support for this telescope, not only from astronomers but from the public, people who had loved Hubble and wanted to see the next great observatory launch. They put together a coalition called Save JWST.

Heidi Hammel: That helped, I think. It also helped that we took a very serious look at where we were in the project and how we had gotten to the state we were. NASA committed to finishing within a specific budget envelope and stuck with that.

Heidi Hammel: But there were definitely over the last more than 20 years some dark moments. Rene recounted the story of a positive moment where we added his instrument. That was a wonderful time for the science working group.

Heidi Hammel: I also remember the science working group meeting where we had to decide to de-scope our mirror aperture from eight meters down to six and a half meters. That was not such a happy decision. I mean I'm happy with six and a half. We debated the science capabilities of six and a half meters, assessed whether or not we could still achieve the core science goals that we needed to do, and the answer was yes. We would have to integrate a little longer because we don't have such a large telescope, but we could still do the science with six and a half meters.

Heidi Hammel: When asked can we go down to four meters again, at that point the science working group drew a line in the sand and said, "Actually, no. We can't. We can't do the science that we've laid out with that size of a telescope." We must have this size of a telescope.

Heidi Hammel: I think that's important because a lot of people ask me, "Why do we need to build such a big telescope? Why don't we just build lots of little telescopes?" Because you can't do the science. The answer is physics. Physics prohibits you from doing certain kinds of measurements, unless you have a large enough aperture to collect the amount of light that you need. Certain kinds of observations absolutely require these larger apertures like we will have with the James Webb Space Telescope.

Heidi Hammel: So, yeah, there were definitely dark times and there were wonderful times. That's the nature of building a very large, complex space telescope. People will remember, with Hubble, the initial trouble that it had on orbit where the mirror was found to be the wrong shape, but exactly the wrong shape, so we could correct it.

Heidi Hammel: But people don't remember that there were decades of trials and tribulations with Hubble before it got to the launchpad. They forgot about that once it was fixed and working fabulously. Now, 30 years later, it's like the iconic best science instrument ever created by humanity. They forget about the decades of hard work.

Heidi Hammel: I'm hoping with James Webb Space Telescope that once we get up at L2 and start sending science back, people will forget about all the challenges and dark times that we've had getting to this point and just focus on the amazing capabilities that this telescope is going to bring to us.

Mat Kaplan: You have brought me back to the discussion that you had not long ago with my colleague Casey Dreier, on the December space policy edition of Planetary Radio, where we talked, or you talked with Casey, about how science drives the design of the instruments that will be necessary to accomplish that science.

Heidi Hammel: Yeah, that's right. Mike talked about that. We don't start off by saying, "Let's build a big telescope. What'll it help us do?" We actually say, "What is the key science question that we want to answer? Then what tool do we need to answer that question?"

Heidi Hammel: So as both Rene and Mike were talking about, we laid out this question decades ago. Can we detect the first light that emerged in our universe after the Big Bang, whether it is the first stars or the first galaxies that formed from the first stars? Because to be able to do that will then allow us to understand the full history of the formation and evolution of our universe to where we are today.

Heidi Hammel: You've got to start at the beginning. You need the baby pictures. Hubble's given us the high school yearbook album pictures of the universe, but we need the baby pictures, too. Webb is the tool that we need to get to that level of science, to the very beginning of the universe. Plus, it'll do all this other great science as well, including my favorite science in the solar system.

Mat Kaplan: Who doesn't love a great baby picture? Mike?

Mike McElwain: I think an interesting thing for a mission like Webb that's taken 25 years to develop is that the science does march on. The landscape shifts and the questions that we're asking evolve. What's a testament to Webb is that it's such a giant leap forward in our new capabilities that the questions we're able to answer today are even more compelling than the ones that were being asked back in 1995, when this whole project got started.

Heidi Hammel: Yeah. Like the questions that we were talking about earlier, can we characterize the atmospheres of planets around other stars? We didn't even have the planets cataloged at that point. We assumed they were out there somewhere.

Heidi Hammel: But in the decades since we began talking about this, we've sent out other spacecraft and used other telescopes to catalog thousands of stars that have planetary systems now. Now with the launch of Webb, we will have the tool we need to do planetary atmospheric characterization of those stars.

Heidi Hammel: So, like Mike said, this is really a testament to the power of building a cutting-edge facility that even if it takes a long time to get it to launchpad, it's so powerful that there are still many questions that require its capabilities.

Mike McElwain: I think what else is really exciting and what we're anticipating is that the discoveries, the ... Maybe the most exciting discoveries we'll make with Webb will be for questions that we don't even know to ask right now. And so, we just have this enormous improvement in capability where we've previously been blind and we'll make all sorts of new discoveries. So everyone just can't wait and just super excited.

Mat Kaplan: Hasn't that always been the case when a new instrument with new capabilities becomes available? Speaking of making it available, Mike, what's the demand for time, for those precious minutes and hours on this telescope, which is still sitting in a high bay in French Guiana as we speak?

Mike McElwain: The science program that will execute has a few different categories in it. So we have guaranteed time observations for people like Rene and Heidi that have been with the project from the very beginning. And so, they get to carry out the first demonstrations, first observations with the observatory and really understand the science performance, characterize how to do the observations, and what science is capable.

Mike McElwain: But we also have a large guest observer program. So those are observations that can be made from the community. For that time, we had over a thousand proposals submitted for review. Those proposals can be on any science topic, and we have review panels.

Mike McElwain: Something that's interesting about the entire proposal process is that nowadays not only are the reviewers anonymous, which has always been the case, but the proposals themselves are also anonymous. And so, it's a double-blind process.

Mike McElwain: So, really, it's just the science being evaluated on its own merits. Who has the best science? What are the most compelling arguments that you can make? Of those, we've selected a little over a year of observations covering the main science themes of Webb, the early universe, galaxies across time, stars and star formation, and other worlds. Those observations will be made throughout the Cycle 1 program, and the data will be made then available through the archives.

Mat Kaplan: Heidi, I was going to bring up that new selection process, because it was one of the most fascinating parts of the conversation that you had with Casey recently on the space policy edition. It has led to already a real change in achieving, well, I'll call it equality among people who want to use these instruments, opportunity and equality, right?

Heidi Hammel: That's right. This dual anonymous process that Mike described, where even the people reviewing the proposals do not know who the people are who are proposing to do that science, has allowed cohorts of people who in the past may not have gotten time for reasons that are probably rooted in innate human bias, the people from smaller universities, people from broader geographic distributions than just the main coasts in the United States, countries in Europe where people don't have a more traditional base of astronomy.

Heidi Hammel: All of those people now have a much greater chance of success based only on their science, only on the science, not on who they are or where they're from or who they went to grad school with.

Heidi Hammel: We have noticed a marked change in the distribution of who is getting time on the telescope. It's a broader category of people who've never ... For Hubble, we have 30 years of experience and 30 years of records. For Hubble, where we've applied this dual anonymous review process, we have noticed a large increase in the number of first-time proposers.

Heidi Hammel: This is people who haven't used the telescope in the past and they have gotten time through this new process. So new voices are coming to the table now, and we expect that to hold true for Webb as well, that we will have a more meritocritous process. So it's a great thing to see that happen.

Mat Kaplan: It's so interesting to see advances being made, not just in the technology that enables this science but in the human practices that drive the science that may be delivered by instruments like this.

Mat Kaplan: Both of you, very busy people, as if dealing with this project wasn't enough. Of course, Heidi, you at AURA, with responsibility for so many instruments, ground-based and up there in the sky through the Space Telescope Science Institute. Mike, I think of some of the other work that I read that you're doing. We won't be able to talk about all of it.

Mat Kaplan: But I wonder if you could tell us about one project in particular that you call PISCES, the prototype imaging spectrograph for coronagraphic exoplanet studies. Are we talking here maybe about a spectrograph that will possibly someday do an even better job of revealing what's in the atmospheres of these worlds circling other stars?

Mike McElwain: Yeah. So one of NASA's big questions that we're trying to answer is are we alone? Unfortunately, Webb does not have that capability. There's a new mission that was recommended recently by the National Academies, building upon Webb actually, and potentially in some of the technologies that we've developed for Webb. It may end up being another segmented telescope that looks quite a bit like Webb. But that future mission is actually setting out to discover Earth-like planets and look for biosignatures. So look for signs of life.

Mike McElwain: Those observations are extremely challenging. It requires large space telescopes, also coronagraph. So the observation itself is very difficult. The star is very bright, your planet is very close to the star, an Earth-like planet, very close to the star, and its contrast is very high, 10 billion times fainter than the star. In order to make those observations, we need to advance a whole set of additional technologies that have been in the works for quite some time.

Mike McElwain: PISCES is a demonstration, the science camera. It's an integral field spectrograph, so we can take a spectrum at every point in the image plane. That's the ideal instrument to make these observations of Earth-like planets and study their atmospheres in reflected light, and look for these signs of life.

Mike McElwain: That was a project that I led about a decade ago. We delivered that out to a test bed from the Goddard Space Flight Center, and built that instrument, delivered it to the Jet Propulsion Laboratory, where it's integrated with their high-contrast imaging test bed. There's an assembly of different technologies for coronagraph observations there, and PISCES is now doing high-contrast observations.

Mat Kaplan: So the beat goes on. Heidi, yesterday, I watched a terrific webinar inspired by the JWST. It came from the Smithsonian Air and Space Museum. It featured Teasel Muir-Harmony and Bhavya Lal, both past guests on this show, talking with University of Alberta historian Robert Smith.

Mat Kaplan: Professor Smith largely talked about what I think he called mega science projects, which would certainly include this new telescope. Though there are many other examples, some successful, some not. They have a longer history than I thought.

Mat Kaplan: Is this what the future is in big science? I mean major, even revolutionary, advances. Are they going to require these kinds of long-term and large investments?

Heidi Hammel: I've watched that seminar, too. It was absolutely terrific. Science takes place at many scales. There is great science that can be done on small scales, excellent science that can be done on medium scales, and there is some science that requires large scales.

Heidi Hammel: It isn't that you can only do big projects or small projects. What all of our decadal surveys have said, they have stressed that if you have a balance of different kinds of science projects, small, medium, and large, that is the most robust way to advance our fields.

Heidi Hammel: And so, there are definitely projects that require extremely large facilities. If we want to clearly characterize the atmospheres of dozens of Earth-like planets around sun-like stars and hope to find the signatures of life as we know it on them, we need the big telescope that we talked about in that previous episode, that our astrophysics decadal survey said we need.

Heidi Hammel: If you wanted to find the Higgs boson, you needed to have a very large collider, whether it was the US Super Collider or the Large Hadron Collider at CERN. That's a political choice whether or not a country or a group of countries decides to push boundaries.

Heidi Hammel: One of the premises that Robert Smith articulated so clearly is that for nations to build the truly cutting-edge, large facilities, you have to move beyond just the science questions. You also need to consider the political environment and the social environment that you're in. You have to consider these things to be international partnerships. That was a crucial takeaway from his talk.

Heidi Hammel: Big projects have more than just the science driving them. I wrote a little paper about this for the planetary community, and one of our takeaway messages is that if your project costs more than a billion dollars, science is necessary but not sufficient. You must take into account all of these other aspects, whether they are the international collaborations, the political considerations of the countries that are funding you, the industry support that you require to build this new technology. All of those factors are all part and parcel of doing large cutting-edge projects.

Heidi Hammel: I'm an American. I believe that our country, the United States of America, can be truly world leaders in space astrophysics and planetary exploration. I also believe that there's great power in international collaboration for these projects. James Webb Space Telescope is a beautiful example of this US leadership, but crucially dependent on the contributions from the European Space Agency and the Canadian Space Agency.

Heidi Hammel: So I think these big projects are things ... We need to do them if we want to truly advance the field. That doesn't mean we don't do small projects as well. We need to do it all within a balanced portfolio of small, medium, and large projects.

Mat Kaplan: Mike, I watched you nodding during that response from Heidi. I don't think you have to deal quite as deeply with the political elements in a project like this. But I just wonder if you also have thoughts about why it is important for enlightened cultures, great societies, if you will, to continue to make investments like the one that has been made in the James Webb Space Telescope?

Mike McElwain: James Webb will make observations that are just so far beyond what the other capabilities could be on the ground or in space, what we've had historically. That discovery space is just so important for really understanding the big questions that we're after, how did we get here, what space is really telling us.

Mike McElwain: Many of the objects Webb will observe have been discovered using smaller telescopes, smaller assets, but to really study them and characterize them, you need a facility and observatory like Webb. And so, Webb will provide the key infrared observations that compliment ultraviolet and visible wavelength observations of Hubble, for example, and Webb will have the sensitivity to make observations that we cannot make in any other way. And so, to really take a big step forward, you need a large space telescope. You need that mega science facility.

Mat Kaplan: Heidi, is a project like this evidence that a society is a great society?

Heidi Hammel: I'm going to paraphrase Senator Barbara Makowski. She talks about this very topic. What she said about Hubble is that a good society can build something like the Hubble Space Telescope, but a great society takes that data from Hubble and makes it available to the entire world. To me, that philosophy holds for James Webb Space Telescope.

Heidi Hammel: I think that there are probably other societies that can build amazing things. To do that, to build amazing things and have it completely open and free to all, anyone can apply to use the James Webb Space Telescope. If their science is robust, that observations will be taken, that data will be in an archive available to all.

Heidi Hammel: I think it is a sign of a great society that we do this kind of science and share it with all of humanity. That is how we as a species progress and grow. And so, I think there is value in doing great projects, mega projects, particularly if you share that knowledge with all of humanity.

Mat Kaplan: I think that's a fine place for us to wrap up this conversation. I also hope that you both know, and Rene knows, and everyone on the team, how all of us at The Planetary Society, all of our members feel, and I suspect everybody listening to this show right now, we cannot wait for that first light from this instrument that may just show us also the first light ever in our universe. Thank you both very much for being part of this. Clear skies.

Heidi Hammel: Thank you. It's been a pleasure to talk with you.

Mike McElwain: Thank you very much.

Mat Kaplan: Want to learn more about the James Webb Space Telescope? Check out the great resources on this week's episode page at You'll also find a link to my monthly newsletter. The December edition has just been published.

Mat Kaplan: It is time for, well, a holiday edition of What's Up with Bruce Betts. He is the Chief Scientist of The Planetary Society. He's back to tell us about the night sky, which you can't see right now. Well, it's daytime, but also because we're having a big rainstorm in Southern California. Nevertheless, happy holidays.

Bruce Betts: (singing).

Mat Kaplan: (singing).

Bruce Betts: All right, enough of that.

Mat Kaplan: I love it.

Bruce Betts: Let's go on to the night sky. Mat, still super cool planets over there in the west, but get them soon, get them fast. They're going away in the next very few weeks. But right now, low on the west, you can still check out super bright Venus. To its upper left, yellowish Saturn. To its upper left, bright, bright Jupiter. All looking super cool right now.

Bruce Betts: And we've got not nearly as bright, Comet Leonard. Comet Leonard is in the evening sky, but really low below Venus. You're in better shape if you're southern hemisphere. It'll be higher up. But, theoretically, you can see it from a dark sight with just your eyes. But I would suggest binoculars and a dark sight. Get a finder chart online.

Mat Kaplan: I heard it was a bust. I mean that it may actually be busting up, that it let people down.

Bruce Betts: Yeah. That's the thing about comets. You can't predict their behavior very well. There's a joke in there somewhere, but I don't know what it is. All right, moving on. Onto this week in space history, it was this week that Apollo 8 launched to head off to the moon with humans, to go around the moon for the first time.

Mat Kaplan: Heck of a mission.

Bruce Betts: We move on to random ... No, we move on to (singing).

Mat Kaplan: (singing). No, there's more, isn't there?

Bruce Betts: (singing).

Mat Kaplan: Oh, that's wonderful.

Bruce Betts: (singing).

Mat Kaplan: Hey, that's terrific.

Bruce Betts: Ladies and gentlemen, boys and girls, I'm here twice on Sundays. Try the steak.

Mat Kaplan: Cleaning up our act and taking it on the road, everybody.

Bruce Betts: Mat and Bruce road trip.

Mat Kaplan: Road picture. That's what we are.

Bruce Betts: Oh, road picture, the Mat and Bruce road picture.

Mat Kaplan: Yeah.

Bruce Betts: You can be Bing or Bob.

Mat Kaplan: I think I'll be Bob.

Bruce Betts: Ah, I got to play the straight man and I have to have a much better voice than I do. We'll work on it. We're absconding with the fact ... Absconding? Anyway, Uranus' moon Miranda, a weird-looking place, has claimed the highest cliff in the solar system, thought to be possibly as high as 20 kilometers or about 66,000 feet, Verona Rupes. By the way, I'm sure you're asking what's Earth's biggest cliff.

Mat Kaplan: I am.

Bruce Betts: Well, it's a lot less than that. Mount Thor on Canada's [Canadias 00:57:16], Canada's Baffin Island, at 1.25 kilometers or 4,100 feet.

Mat Kaplan: Man.

Bruce Betts: On from the cliffs and on to the mythical creatures. In our trivia contest, I said, "I am a mythical creature. What am I?" I'll give you a hint. I'm also a category of small-body objects that orbit between Jupiter and Neptune. What am I?

Mat Kaplan: Boy, did people love responding to this, and the fact that you said, "What am I?" as you will hear in moments. Let me tell you who I believe is the winner first. In fact, I'm sure it's the winner. What's interesting about this is that he did win once before, but it has been over five and a half years. He regularly enters the contest.

Mat Kaplan: So congratulations, [Marcel Jann Krissman 00:58:08], I hope I'm saying that correctly, in the Netherlands. Marcel Jann-

Bruce Betts: Wow. He earned it. Congratulations.

Mat Kaplan: He said you're a centaur, Bruce.

Bruce Betts: I am indeed a centaur and I don't know why I talk like this.

Mat Kaplan: Really? I would think centaurs would have deep voices, like this.

Bruce Betts: Well, that's the horse end. My horse end has a very deep voice.

Mat Kaplan: Okay. Well, Marcel, you are going to receive a Planetary Society Kick Asteroid rubber asteroid for your trouble. Thank you so much for being a part of this and for hanging in there with us.

Mat Kaplan: I got other great stuff. Well, here's one from Gene Lewin in Washington, one of our poets. "Between Jupiter and Neptune roam ambiguities of myth, unstable orbits or temperament in varying size and width. Some like comets with a tail, some like asteroids more rocky, named for the centaur of Grecian lore, a horse with a built-in jockey."

Bruce Betts: Wow. Rocky and jockey. Very nicely done.

Mat Kaplan: Nice rhyme. I bet that one hasn't been made very often. Darren [Ricci 00:59:23], also in Washington, he says that these centaur asteroids are also known as future Jovian snacks.

Bruce Betts: Some of them, yeah. Some of them.

Mat Kaplan: Mark Little in Northern Ireland, "There are more discovered centaurs in space, nearly 250, than in all of Greek mythology, just 82. Science grows from the seeds of our imagination," says Mark. Well done, well said.

Mat Kaplan: [Kari Rao 00:59:55] in Texas. "I've often wondered about the lower back pain of most centaurs. Can you imagine standing upright while the lower half is running at one horsepower?"

Bruce Betts: No, it's not easy.

Mat Kaplan: Mel Powell in California. "I wanted to be a centaur when I grow up, but my parents maybe go to law school."

Bruce Betts: What a disappointment.

Mat Kaplan: I love this one. This is like my favorite. [Jule Crye 01:00:21] in Texas. "Bruce could be as centaur. Thanks to radio, we would never know. For the record, I've only seen Bruce on screen from the shoulders up. All I'm saying is that there's a non-zero possibility he's got some extra legs."

Bruce Betts: We should move on. We should move on.

Mat Kaplan: Don't you want to give that like a ... I can't do it well enough. There were several versions of this. Oh, that's good. There were several versions of this, but [Jerry Robinette 01:00:51] probably said it best. Jerry is in Ohio. "Bruce is a centaur? Well, that might explain some things, or was he just horsing around?" Yeah.

Mat Kaplan: Finally, from our poet laureate Dave Fairchild in Kansas, "A mythical beast is the centaur, half horse and the other half man. A Zodiac sign called the Archer, and Greece is where all this began. The centaurs that orbit by Neptune are comet and half asteroid. The first one discovered was Chiron, planetesimals out in the void." Nice work, everybody. Thank you very much. What do you got?

Bruce Betts: Who do we have to thank for suggesting the planet name Uranus? Go to

Mat Kaplan: You have until the 22nd. That's Wednesday, December 22nd, at 8:00 AM, Pacific Time, to get us the answer. Here's the something new for you. We got at headquarters, apparently, a whole pile of International Space Station 2022 calendars. So we will send the winner of this contest one of those. Good luck to all of you. Although only one of you's going to win. So sorry about that. I think we're done.

Bruce Betts: All right, everybody. Go out there, look up the night sky, and think about what your personal barcode would look like. Thank you and good night.

Mat Kaplan: Well, that's a horse of a different color, and that's a different movie, too. That's Bruce Betts, the Chief Scientist of The Planetary Society, who joins us every week here for What's Up.

Mat Kaplan: Planetary Radio is produced by The Planetary Society in Pasadena, California, and is made possible by its farsighted members. You don't need a telescope to find our membership page. It's Mark Hilverda and Jason Davis are our associate producers. Josh Doyle composed our theme, which is arranged and performed by Pieter Schlosser. Ad astra.