EPISODE 142: EUROPA CLIPPER: VOYAGE TO A WATER WORLD

Transcript

Andres Almeida (Host): Welcome to Small Steps, Giant Leaps, the podcast from NASA’s Academy of Program/Project and Engineering Leadership, or APPEL. In each episode, we explore the experiences and lessons learned of NASA’s technical workforce. I’m your host, Andres Almeida.

Europa Clipper is NASA’s first mission dedicated to studying an icy ocean world. Launched aboard a SpaceX Falcon Heavy rocket on October 14, 2024, from Kennedy Space Center, the spacecraft is set to arrive at Jupiter in April of 2030 to conduct sweeping flybys of Europa. Europa is one of Jupiter’s four large Galilean moons. It’s roughly the size of our moon, but what’s most intriguing is that it may harbor the conditions for life in the massive ocean beneath its frozen surface. What we learn could open up the science floodgates to other ocean worlds across the solar system.   

With us today is Dr. Bonnie Buratti, Europa Clipper deputy project scientist at NASA’s Jet Propulsion Laboratory in California. She’s worked on several planetary missions, including Cassini, the first mission to conduct a detailed study of Saturn’s elaborate ring system, atmosphere, and moons. During a flyby of Saturn’s icy moon Enceladus, her team discovered an active water plume spewing out of its south pole. The finding expanded scientists’ horizons – where there’s water on Earth, there’s life. Could the same conditions exist on other water worlds? 

Host: Hey, Bonnie, thank you for being here.  

Buratti: Thank you for having me, Andres. 

Host: Could you explain the main goals of the Europa Clipper mission and its significance in the search for life beyond Earth?

Buratti: Yeah, so let me just go back a step, and that is, you know, 30 or 40 years ago, scientists thought that life arose in the shallow oceans of the earth, where you had seas that were, you know, just a few feet deep. You zapped them with sunlight or lightning, amino acids formed, and life somehow magically arose out of that. Well, our view of that has changed. 

We think that the most primitive life on the Earth has actually formed in the deep oceans. If you look on Earth, especially along areas where there are trenches in in the deep oceans. There are these hot spots, these so-called smokers, or thermal vents, where there’s primitive bacteria. And we think that was how life originated on the earth. 

So, since there are oceans on many worlds in the solar system, including Europa, which is a moon of Jupiter – it’s about the size of our own moon. It’s one of the four Galilean satellites discovered by Galileo in 1610 – there is almost certainly a deep ocean underneath there, containing possibly twice as much water as is in the earth’s oceans. 

Basically, we’re not looking for life. We’re not a life search mission. We’re looking for habitable environments. We think there might be an environment similar to that on which life arose on the Earth. That’s the main goal of this mission: to look for a habitable environment. 

Host: And that’s an important distinction, that this is not a life-searching mission.

Buratti: Yeah, it’s too ambitious. I mean, you know, NASA, we want to look for life where there’s liquid water, but we first of all have to study that environment and see if it could sustain life – life as we know it. It’s quite a big task. So, we’re just looking for where life could exist and thrive. 

I mean, on the earth, wherever there’s liquid water, there seems to be life. So, so why not? 

Host: What has been your role in the mission, and how has your own research influenced the science goals? 

Buratti: Yeah. So, I have actually only been on this mission for two and a half years. I did my thesis on Europa, I got my Ph.D. at Cornell University, and I did my thesis on Europa. But then when I came to JPL as a postdoc, right after I finished my thesis, I started working on other things. I was working on comets and small bodies. I worked on a lot of missions and worked on New Horizons, which had gone to Pluto. But for most of the past couple decades, I’ve been working on the Cassini mission, which went to Saturn, studied a lot of the moons there. 

My own research: I’m interested in not just the composition, but kind of what the texture is, what the evolution is, how has the surface evolved? So, in my thesis, I showed that Europa has a very unusual surface structure. It’s smooth, but it kind of has some type of particles on the top. It has undergone recent activity. There are hardly any craters on the surface. So, all those things kind of folded into this current mission. Titan has an ocean underneath it. Enceladus has an ocean and huge plumes and activity. So, all those insights I did carry over to this mission, looking for, not only trying to understand the ocean underneath. One of our goals is to understand how deep is the ice crust. I mean, the ocean is underneath. There’s a crust of ice on the top, and we don’t know how thick it is. It might be 15 miles, 20 kilometers. We’re trying to find that out. But we know that Titan, the large moon of Saturn, and Enceladus, the active moon of Saturn, are also ocean worlds. 

So, we’re just trying to expand our knowledge of ocean worlds. 

Host: And is it known whether Europa’s surface is active? Is it in motion? 

Buratti: Well, this is, I think, one of the most interesting questions in the mission. There have been reports of activity, both from the Hubble Space Telescope and some other ground-based observations. Also, Galileo, Galileo the spacecraft (not the man, but the spacecraft). When it went by Europa, it picked up this kind of, it’s like a draping of the plasma in that area around the magnetic field of Europa. And it suggested there might be a plume there. And then there are two or three observations from the Earth that show water vapor emission from the surface of Europa. However, a lot of scientists have looked at it at other times and not found it. So even though it’s kind of tantalizing that it is active, it’s kind of sporadic. It’s not like Enceladus, where there’s this huge plume that you can see coming out all the time. That’s what we saw in Cassini. 

But I think one of the interesting things is, you know, how active is it right now? Is there ongoing geology? We see evidence that in the recent past, there were possibly cryovolcanoes, water ice coming to the surface and sublimating. It’s quite intriguing. You know, I think that’s one of the big questions in the mission: Is it active now? 

Host: Could you talk a bit about the spacecraft itself and some of its key instruments. 

Buratti: Yeah, yeah. So, this is a flagship mission. This is NASA’s current flagship mission to the outer solar system. A flagship means it’s, it’s very, very sophisticated. It really has what you would call a loaded payload. So, we’ve got, really nine or 10 instruments. It depends how you count. We have spectrometers that are state of the art. So, we have a UV spec, ultraviolet spectrometer, which is going to look for not only the composition of the surface, but also, it’s going to look at the atmosphere and plumes, try to characterize them. Then moving up through the spectrum, we have a camera. There’s actually a wide-angle and a narrow-angle camera is built by the Applied Physics Lab. It has filters on it so it can look at colors. We’ll get resolutions better than a meter over a certain fraction of the surface. 

Further, we have an imaging spectrometer in the near-infrared, which is going to map the composition. And then moving up one more slot, we have a thermal infrared mapper that is going to look for hot spots and understand the texture of Europa. Our main goals are to characterize the composition, the geology, the interior (meaning the thickness of the ice shell and the ocean), and then finally, try to assess it as a habitable environment. 

Host: Just what makes Europa such a challenging moon to study. Jupiter’s harsh environment with its radiation is one factor. But what else is there? 

Buratti: Yeah, so we have a whole other slew of instruments, that is our fields and particles, which are sometimes called in situ instruments. And we also have a radiation monitor, but we have a plasma detector, a magnetometer, a mass spectrometer, and a dust detector. And those instruments will look at the environment. And as you mentioned, it is not the nicest environment in the world. 

You know, the magnetic field of Jupiter is huge. It’s thousands of times more intense than the earth. It’s equal to, like, millions of chest X-rays if you’re just standing there. But we have a couple things we’ve done. The first one is we only stay in the inner part of Jupiter’s particle and magnetic field for a very short period of time. We’re not actually orbiting Enceladus, which is close. (It’s Io, Europa, Ganymede, and Callisto are the four main Galilean moons.) We stay outside orbiting Jupiter, and then we swoop in for about 50 flybys. So, we only stay in that harsh, environment for a short period of time. 

We’ve done a couple other things. We’ve put the most sensitive electronics in this protective vault, and we also monitor the radiation and have radiation-hardened parts. 

Those are the main things that we’re doing to not destroy our spacecraft or our instruments, or very sensitive instruments.  

Host: Would you say the mission profile is similar to Cassini?

Buratti: It’s simpler. On Cassini we were looking at all the moons, the main moons. We looked at Titan. We looked at Iapetus. And on the way, in the two weeks before we went into Saturn orbit insertion, we got these great views of Phoebe, which is this outer moon that is probably a captured Kuiper Belt object, so it came out from further in the solar system. So, we got our view of that, that primitive body, and then we got many flybys of the moons, of course, of Saturn, the rings. It was way more targets than on Europa Clipper. On Europa Clipper, it’s mainly Europa we’re looking at. We’re looking at a detailed view, looking for a detailed view of this ocean world. 

Host: What are your top questions that you want to see answered from this mission?  

Buratti: I’m really interested in whether it’s currently active. I would be overjoyed if we actually saw a plume or some type of activity. That’s kind of not one of the main science goals. It’s kind of like peripheral. The main thing is we need to show that it has all the elements of a habitable environment. So, we have to confirm that there’s a deep ocean – water. We have to show that there’s some type of chemistry that would support life. So, we’re looking for organic molecules that’s things that have carbon, hydrogen, oxygen and nitrogen that could act as food. We’re looking for chemical potentials, if there’s if the ice is salty, you know, down at those thermal vents, maybe there’s ions down there that are providing some energy. 

Now, remember, Europa gets heated from the strong gravity of Jupiter as well. Since there are huge tides there, it kind of causes Jupiter to flex. When it’s close, it kind of gets squashed down, and then when it goes further away, its orbit is not perfectly circular. When it gets further away, it gets that flexing gets released, and then heat is released. It’s kind of mechanical energy being released as heat. So, we have that form of energy, but we’re also looking for chemical energy. So, you know, those are the things we need. We need energy, water and food for life. So that’s basically the main goal, the mission. 

Host: How has the teamwork shaped the mission’s development? 

Buratti: Yeah, well, we have worked mainly with Applied Physics Lab, which is part of Johns Hopkins University. We’ve also partnered with NASA Goddard Space Flight Center in Greenbelt [Maryland], so we’ve worked on the spacecraft bus, the structure of the spacecraft together with them. NASA Marshall has done a lot of the management, but we don’t have, actually, any instruments that are contributed by foreign partners. But we do have team members. In fact, my past postdoc [researcher] came from France, and she’s gone. She came from the European Space Agency. This is Ines Belgacem. She just got a job back at the European Space Agency. So, we have scientists coming in and out from Europe, but it’s not like the Cassini mission or the Rosetta mission, where we had a big cooperation with Europe. 

However, the European Space Agency has a mission that is going to Jupiter – JUICE [JUpiter Icy Moons Explorer]. It’s already been launched. It’s going to get there a little bit after us, and we’ve launched. They actually launched before us, but we get there a little bit sooner, and we have a team. We’re cooperating with them. They’re mainly going to look at Ganymede, and we’re mainly looking at Europa, but they are a couple Europa flybys that are, there’s one that’s like within a few hours of each other. So, we have already set up cooperative team with the JUICE mission leadership. 

Host: What is the current mission timeline for Europa Clipper? 

Buratti: So, we launched. We didn’t launch on the first day, but we launched near it. I mean, you probably heard the story about the hurricane [Milton] and all that, but then the weather got really good and we launched. So, we’re going to do our first trajectory correction maneuver. I think it’s November 3. It’s a very small correction maneuver. I think we budgeted like 20 meters per second, but we only need to use four or five, because the launch was really good. It really got us on our trajectory. So that’s the first thing. 

Let’s see. We’ve deployed the solar panels. That was kind of stressful. In a couple weeks or three weeks, we’re going to deploy the magnetometer. The solar panels are all at, you know, 100% power. They’re working really well. We’re doing checkouts now. The instruments are off. They’re kind of, you know, they’ve got some of their heaters on, but we’re going to, like, cycle through the instruments and, you know, turn them on and just check them out. 

But our first kind of major event that I think the public would know about is we have a gravity assist at Mars. But we can’t go on a direct trajectory to Jupiter, because our rocket that launched us – it was a Falcon Heavy from SpaceX – it was a great launch and rocket, but it just doesn’t have enough energy to put us on a direct trajectory. So, we have to go into the inner solar system and do this thing where you kind of pick up momentum from other planets. 

So, our first planet is Mars, and we are actually going to take some calibrations there. The thermal mapper needs to check a calibration and an algorithm to calibrate some of their data. And then the radar. We have a very, very innovative radar. It’s an ice-penetrating radar, and there are six antennas, and they’re on the solar panels. We never had a chance to do an end-to-end test on radar. We are going to do the end-to-end test at Mars. There’s a similar heritage and instrument. A couple, MARSIS and SHARAD, are on previous Mars missions orbiting so we can compare the data and calibrate and test the ice-penetrating radar fully. So that’s the first thing. That’s going to be March I think right now it’s March 3. It moved around a little bit because of the launch. March 3. And then we loop around the inner solar system. 

And our final flyby is of the earth, which will be December 3, 2026, and then we reach Jupiter. Our Jupiter orbit insertion will be – right now, it’s April of 2030 back to flyby. 

Host: Does the spacecraft have to catch up to planets when that happens? 

Buratti: So yes, it does have to. They kind of meet the planet is on the orbit, and the spacecraft comes in and just meets it and picks up some of that momentum from the planet. 

Host: So, if Europa Clipper finds compelling evidence of conditions that could support life, what might be the next steps for future exploration of Europa or other ocean worlds? 

Buratti: Yeah. So, you know, we tend to do this in cooperation with the National Academy of Sciences. NASA often asks for advice from the National Academies. So that would probably happen, because they are like, two directions we could go in. Should we go back there and put a lander and investigate it in detail? And that’d be one way to go, or we could look at other ocean worlds?

Now, we, I know that in the last advice that the National Academies gave us, it suggested going to Enceladus, going back to Enceladus, and doing a mission there. And of course, there’s, there’s the Dragonfly, which is an APL mission, Applied Physics Lab mission that is going to Titan. They’re working on that now. So, we ask for advice, using all the scientific parameters and questions and data that we have. What would be the most scientifically useful thing to do next? So, I think we would ask for it could either go towards Orlando or looking at other ocean worlds. 

Host: So, Europa Clipper is going to make a big leap, hopefully. What was your giant leap? 

Buratti: Well, I’ve had a couple of leaps. I mean, the first thing was, I had a great graduate school mentor, Joe Verca. He was one of these people that, you know, as you’re an undergraduate, you kind of flounder around. I was an undergrad at MIT, and it was just totally exciting, and I loved it. But you kind of, you know, flounder around and get, kind of like, off on various tangents and everything. And then I got to graduate school, and here was this person who was totally focused, you know, if you’d just cut out all the crap in your life, here’s, here’s what you’re going to do your thesis on, you know, here are the steps, you know. And, you know, I thought at first: One, this is kind of like regimented. But he totally guided me through this research project. Oh, that was my thesis. And, you know, back now that I can look at it decades later… I mean, those papers that came out of that thesis, you know, they got a lot of, they got a lot of attention, a lot of citations, all that kind of stuff. 

Then, when I came to JPL, I got on a couple missions. I got on the CRAF (the Comet Rendezvous, Asteroid Flyby) imaging team, the Mars Observer infrared spectrometer team. But both those missions, CRAF was canceled, and they deselected the imaging spectrometer. So, you know, there was, you know, a big push and then a disappointment. I just kind of learned what my advisor [said]: Just press on, you know, in the face of disappointment. Press on regardless, you know. 

So, I was working on research, got involved in other things, you know, went on to Cassini. Had a couple other missions. There was the Pluto mission, New Horizons, which was also run out of that APL, led by Alan Stern. But all those things, you know, just gave me really great opportunities. Working with amazing teams, just like the Europa Clipper team here at JPL is amazing. It was just really a privilege to work on that. And I would say they’re just a bunch of breaks, some disappointments, but when you do get a disappointment, you just have to press on. 

Host: One more question for you. So, on board Europa Clipper, aside from the science, there is also something sentimental. It’s a plaque that relates to a poem by the National Poet Laureate, Ada Limón. What is the significance there? 

Buratti: Yeah, this is big. Okay. Andres, this is… Thank you for bringing that up, because one thing about science is some of the questions we’re looking for: not only the search for life, but you know what is not so much the purpose of our existence, but these great questions bring us closer to the appreciation of precious life on Earth. And I know that I’m not sure who it was. Someone from JPL approached the Library of Congress, which has the poet laureate program, and asked Ada Limón, who was the poet laureate at that time, she still is (she actually got, you know, another term), whether she would do this poem. And lo and behold, she did. 

[She] wrote our very own poem “In Praise of Mystery” which ties life on Earth as not only dependent on water, but the sense of mystery and this desire to, to look beyond and answer some of the questions that that, that poets really try to, if not answer, at least bring up and have us think about. 

So, Ada came out to JPL while we were building the spacecraft and kind of caucused with the scientists. And she wrote the poem in her own hand on this plaque. And we also had a couple other things on the plaque. We had the Drake Equation, which actually Frank Drake was one, was one of my mentors and professors at Cornell. Drake Equation, which predicts the amount the number of civilizations that can communicate in our galaxy that have intelligent life and communicate – it’s very uncertain. And then also Ron Greeley, who is Bob Pappalardo’s thesis – I have to mention, the project scientist is awesome, he’s Bob Pappalardo, who’s been with this mission since the beginning. His mentor was Ron Greeley. And Ron passed away before his time, but his memory lives on, and his there’s a little portrait of him on the plaque too. And then on the other side there are the wave forms for water being said in 104 languages. 

So, this is this plaque that we had made up and is on the spacecraft. It also has two, more than two and a half million signatures of people who signed on to Ada’s poem and are also going to be sent in orbit around Europa. So, this is an inspiring message from Earth that summarizes our desire for exploration and the search for at least a habitable environment, if not life, and posing the great questions. 

Host: Thank you, Bonnie, thanks for your time today. I really appreciate it. 

Buratti: Okay, thank you, Andres. Thank you so much. 

Host: That’s it for this episode of Small Steps, Giant Leaps. For more on Dr. Buratti and the topics discussed today, visit our resource page at appel.nasa.gov. That’s A-P-P-E-L dot NASA dot gov. And don’t forget to check our other podcasts like “Houston, We Have a Podcast” and “Curious Universe.”