Planetary Radio • May 13, 2020

Looking for Life in Alien Oceans

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Kevin hand

Kevin Hand

Deputy Chief Scientist for Solar System Exploration for Jet Propulsion Laboratory

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Mat Kaplan

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

Jet Propulsion Lab astrobiologist Kevin Hand has just written Alien Oceans: The Search for Life in the Depths of Space. Kevin and Mat explore these seas and whether they may have nurtured organisms with no connection to life on Earth. You may win a copy of Kevin’s excellent book in this week’s What’s Up space trivia contest with Bruce Betts.

Alien Oceans Book Cover
Alien Oceans Book Cover Book cover for Alien Oceans by Kevin Hand.Image: Princeton University Press
Europa Lander artist's concept
Europa Lander artist's concept Europa Lander is a concept for a potential future mission that would look for signs of life in the icy surface material of Jupiter's moon Europa.Image: NASA / JPL

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Trivia Contest

This week's prizes:

Alien Oceans: The Search for Life in the Depths of Space by Kevin Hand.

This week's question:

Who is the Northrop Grumman Cygnus cargo spacecraft NG 13 named after?

To submit your answer:

Complete the contest entry form at or write to us at [email protected] no later than Wednesday, May 20th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

About how much mass has the Hubble Space Telescope gained since its launch?


The winner will be revealed next week.

Question from the April 29 space trivia contest:

Whose silver astronaut lapel pin is on the Moon?


Alan Bean left his own and Clifton Williams’ silver astronaut pins on the Moon during Apollo 12. Williams had died in a plane crash before he could fulfill his role as Lunar Module Pilot. Bean replaced him.


Mat Kaplan: [00:00:00] Alien Oceans, 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. We now believe that many moons in the outer solar system are hiding warm oceans of liquid water under blankets of ice. Kevin Hand wants to know if any of those oceans are also hiding life. We'll talk with Kevin about his excellent new book. It includes his fascinating speculations about the possibility of intelligent life out there. Bruce Betts is also standing by with this week's What's Up, including your chance to win a copy of Kevin's book.

Headlines from the Downlink are moments away, but I've got a couple of special announcements first. The May 14th Planetary Society Live will bring you Space Policy Edition Live. For the first time, Planetary Society chief [00:01:00] advocate, Casey Dreier, and I will take your questions beginning at 9:00 AM Pacific, noon Eastern, and 1600 UTC. I'm sorry I couldn't give you an earlier heads up. The webcast will be available live and later on demand at

Then on Tuesday, May 19th, Explore Mars is bringing me back for a live conversation with the great John Grunsfeld. The scientist, former astronaut, and NASA chief scientist will talk about the 30th anniversary of the Hubble Space Telescope. This one is set for 10:00 AM Pacific on the 19th, that's 1:00 PM Eastern, and 1700 UTC. You'll find it at

Now those Downlink headlines, beginning with an update on China's successful test of the Long March 5B heavy-lift rocket. A big section of the launcher came down safely in the Atlantic Ocean. Success was [00:02:00] vital for the launch this summer of China's Mars mission and construction of its planned space station. Kevin Hand and I will spend a lot of time talking about Europa today, that mysterious moon of Jupiter has never looked better now that old images taken by the Galileo orbiter have been reprocessed. There's a stunner of the fractured icy surface at The old and improved pics will be used to help plan the Europa Clipper mission.

NASA, I'm ready for my closeup. The agency announced that Tom Cruise will film a movie aboard the International Space Station. That's about all we know so far, but it's enough to make me envious, that's if Cruise actually gets to visit the ISS, which also isn't yet clear. There's much more to see and read at

I don't know of a more passionate or articulate advocate for the exploration of space than [00:03:00] Kevin Hand. Kevin is the principal investigator and director of the Ocean Worlds Lab at the Jet Propulsion Laboratory. He's also the pre-project scientist for the effort to send a lander to Europa, as a follow-on to the Europa Clipper orbiter. The JPL website says he has made nine deep dives to the floor of Earth's oceans, but it's really those dark yet warm oceans on other worlds that fire his imagination and inspired his new book.

Alien Oceans: The Search for Life in the Depths of Space has just been published by Princeton University Press. I so look forward to reading it and as you're about to hear, I wasn't disappointed. Kevin and I talked a few days ago. Kevin, welcome back to Planetary Radio. I love this book, Alien Oceans: The Search for Life in the Depths of Space. I learned a lot and it was really fun to read, and I'm glad you're here to talk about it.

Kevin Hand: Well, thanks so much, Mat. Pleasure [00:04:00] to, uh, be with you again, uh, virtually and, uh, delighted that you enjoyed the book.

Mat Kaplan: I'd use the word fun. That is the right word.

Kevin Hand: [laughs]

Mat Kaplan: And it also in parts dramatic, I mean, right from the first page, in which we very appropriately discover you in a submarine wondering if you're gonna survive.

Kevin Hand: [laughs] Yeah, well, it's, uh, uh, I kind of wanted to transport the reader into these environments that, that, uh, we think could be analogous to, uh, the deep ocean environments out there and these alien oceans in the outer solar system and possibly beyond. And well, part of what has been, um, exciting in, in my scientific career has been the opportunity to explore these, these beautiful and bizarre environments on planet Earth that merit a tremendous amount of study in their own right, but also help provide a bridge when we think about potentially habitable environments beyond Earth.

Mat Kaplan: They're all we've got, right? They're the best analog [laughs], they're the only analog that we [00:05:00] found. I mean, we'll get to some of the data that's been collected in moments, but, but really it's, uh, uh, we can extrapolate from down here somewhat, right?

Kevin Hand: That's right. And so when we think about these oceans beneath the ice shells of Europa and solidus Titan and, and, uh, numerous other moons of the outer solar system, the physical and chemical conditions that exist within those liquid water oceans may be somewhat comparable to the, the conditions that we find in the depths of our own ocean. And so there's a, uh, beautiful win-win of, of exploring here with an eye towards there.

Mat Kaplan: I gotta say I envy you having had the chance to get down there, or up close and personal with those hydrothermal events, but, uh, we'll, we'll come back to those as well.

Kevin Hand: They are a site to behold, that's for sure.

Mat Kaplan: [laughs] On a stray, again, here for a moment. Do you remember your reaction when Cassini first flew through Enceladus's plumes and, and tasted or, or sniffed out [00:06:00] organic molecules?

Kevin Hand: [laughs] Well, when that picture came back, uh, I wasn't on the Cassini team. I was at JPL at the time. And uh, when we all saw that picture of the, of the sunlight reflecting off of those jets erupting out of Enceladus's south pole, uh, talk about a jaw-dropping image that, um, that is hands down one of my all time favorite pictures from the history of, uh, of, uh, solar system exploration.

Mat Kaplan: But what about the organics? It wasn't able to find [laughs] ones that were as complex as you and a lot of others might have wished, but it did find organics, right?

Kevin Hand: That's right. And the Cassini spacecraft was not designed with instrumentation that was targeted at searching for large complex organics. It, it had some capability. It had two mass spectrometers on it. The original target for organic chemistry was Titan's atmosphere.

Mat Kaplan: Mm-hmm [affirmative].

Kevin Hand: And so of course, Cassini studied Titan's atmosphere and [00:07:00] re-revealed some of the, the organic tholin type of, uh, materials in its atmosphere. But the discovery of organics in the plumes of Enceladus certainly wet our appetite with the potential habitability of that subsurface ocean. But those mass spectrometers were not able to, uh, for example, reveal amino acids or, or the, the sort of sub unit compounds that we might expect to, to be associated with, uh, with life as we know it. So just enough to, to get us, uh, really excited about going back.

Mat Kaplan: [laughs] Wet our appetite, so n-no pun intended [inaudible 00:07:38].

Kevin Hand: [laughs] Yeah. 100% intended.

Mat Kaplan: [laughs] Um, were you surprised to learn not how rare ocean worlds are in our solar system, but, but really how common they are. I mean, you go through th-the whole solar neighborhood kind of one by one and there are a bunch.

Kevin Hand: That's exactly right. And, and this sort of new Goldilocks, as I described in [00:08:00] the book, has revealed to us that the tidal energy that, uh, helps maintain the subsurface liquid water oceans could be responsible for not just providing the most abundant volume of habitable real estate in our solar system by merit of these large oceans within Europa, Enceladus, et cetera, but it could be that throughout the galaxy, throughout the universe, the, the, the vast majority of liquid water is to be found within these ice covered moons or planets that are being heated from within by the tidal dissipation that these worlds experience as they orbit their giant planet or some other body that causes them to, to stretch and relax in a, in a tidal dance.

Mat Kaplan: Hmm. What I'm leading up to now is your portion of the book that [00:09:00] helps folks like me understand how we've developed this evidence, that there are oceans hidden under the surfaces of all these worlds. And it comes down to, you, [laughs] I love it, the rainbow connection, babysitting, and airport security.

Kevin Hand: [laughs]

Mat Kaplan: And I, I won't, I don't want to get us into a lot of technical stuff elsewhere in this conversation, but could you go through those? I mean, begin with what you meant by the rainbow connections, uh, uh, uh-uh-uh apologies to Kermit.

Kevin Hand: [laughs] Right, right. So, I'll, I'll keep it brief for the sake of your listeners. But as you know, in the book I go into, uh, a great detail on this. But, uh, in brief, the discovery of the ocean within Europa, which serves as a bit of a template for how we found oceans elsewhere, I like to break into three easy pieces. The first is find a rainbow connection. And by that I mean use spectroscopy, which is, uh, an astronomy technique, a chemistry technique. Really it's a fancy word for saying I [00:10:00] study rainbows. [laughs] And so the rainbow connection is using spectroscopy to determine that the surfaces of these worlds are made of water ice.

Then babysitting a spacecraft basically refers to the careful monitoring of a spacecraft and that spacecraft's trajectory as it goes by a world like Europa. And from that careful babysitting, you can then tease out the internal mass distribution of a world. And in the case of Europa, that revealed that not just the surface but the outer shell of Europa, down to a depth of roughly 200 kilometers or roughly 120 some odd miles, is water in some phase. So that was step two. We, we now know that, that there's water in some phase down to a, a significant depth, uh, beneath the surface.

And then the third piece of the puzzle is to adhere to airport security. And here [00:11:00] again, a lot of detail in the book. It's beautiful physics. It's a, it's one of my favorite, uh, pieces of, of physics in, in how the solar system works. But basically the analogy is that Jupiter has a magnetic field that is time varying. It's, uh, Jupiter is rotating and, and it sweeps past Europa, and that time varying magnetic field excites induced electric currents, uh, and an induced magnetic field within Europa. And that is what the Galileo spacecraft detected. And the physics is very similar to airport security.

When you walk through airport security, one of those doorways, you're walking through a changing magnetic field, and if you've got a conductor in your pocket, the alarm goes off and you get the pat down and maybe you miss your flight and those. Well, when the Galileo spacecraft flew by Europa, the alarm went off and the induced magnetic signature of Europa was [00:12:00] telling us that there's a conducting layer beneath Europa's surface. And the best explanation for that conducting layer is a salty liquid water ocean of roughly 100 kilometers or, or about 60 miles in depth.

Mat Kaplan: Wow.

Kevin Hand: It's beautiful physics.

Mat Kaplan: It really is. I don't want to get you in trouble with, uh, airport security, but, but you, you'd attempted to, uh, conduct this experiment, right? As you were, uh, uh, you went on certain flights?

Kevin Hand: [laughs] That's right. Yeah. This is back in the early 2000s when I was still a grad student and I was doing much of this physics as, as part of my, uh, PhD, uh, and never, never successfully got the alarm to go off, uh, just with a, a [laughs], a, a bottle of salt water. Um-

Mat Kaplan: [laughs]

Kevin Hand: So yeah, and then in the book I apologized to anybody that, uh, that I, that I might have held up in those endeavors.

Mat Kaplan: So much of this data that we've picked up, uh, uh-uh, not in the Jupiter system, but at Saturn, of [00:13:00] course, we've gotten from Cassini, that glorious mission. Are we still learning from the data collected by Cassini?

Kevin Hand: Oh, absolutely. Cassini is going to continue to yield all sorts of exciting results for at least, uh, another decade or more. Uh, th-think about it. I did, I did much of my PhD work on Galileo data after [laughs] the Galileo, uh, spacecraft had been, uh, had been sent into Jupiter and, and had, had finished. These datasets will continue to be mined for years and years and numerous PhDs and postdocs and interns will help do experiments, do models to better understand exactly what, uh, what this treasure trove of data is telling us.

Mat Kaplan: Let's jump back to Jupiter and Europa. Uh, I mean, we could spend the rest of our time just talking about the upcoming Europa Clipper mission that so many of us are looking forward to.

Kevin Hand: Mm-hmm [affirmative].

Mat Kaplan: But it is an orbiter, a Jupiter orbiter, and, no, a lot of [00:14:00] people don't realize. What would a Europa Lander be able to tell us that the Clipper probably won't be able to?

Kevin Hand: Clipper is a, uh, a fantastic mission that has an incredible payload of instruments that will map out at a, at a global and regional scale, just about everywhere on, uh, on Europa. It'll take images and I'll take, um, spectra, and, and, uh, visible the infrared spectra. And it'll also collect mass spectra as it flies by and, and hopefully finds plumes. And it's got ice penetrating radar on board. So there, there are many different ways in which the Clipper mission will help us better understand Europa as a world in and of itself.

But when it comes to actually searching for signs of life, looking for biosignatures, that's when you really need to get down to the surface and scoop up a sample and, and look in [00:15:00] detail at, uh, at some material that, that you've, you've collected. And so a lander on the surface of Europa, or any ocean world for that matter, is really the key to searching for signs of life.

And coupled with that, such a mission also provides critical ground truth to all of those remote sensing observations that have been made. And that, and that's really critical. Think about the Mars program. Uh, we've had lots of orbiters that have done remote sensing around Mars, but it's really only once you get down to the surface and really put a, a rover or some sort of vehicle that can sniff around and, and directly analyze the geology and geochemistry, that the full remote sensing dataset of the sun makes a lot of, uh, a lot of sense. So biosignatures and ground truth are, uh, are the, the, the big ticket items for, uh, for a lander on the surface of Europa.

Mat Kaplan: It was looking [00:16:00] pretty good, at least, uh, in Congress, uh, for a Europa Lander mission to get some kind of a start a while back, and, and, and maybe doesn't look quite as good now. But from what you told me, when we were talking just before we started recording this conversation, there's still a lawful lot of interest in the science community in a lander.

Kevin Hand: That's right. We, uh, we were planning on having a conference about a Europa Lander or more broadly, we like to also refer to it as an ocean worlds lander. Uh, the, the, the technology that we developed for landing on Europa can also be used for Enceladus and Ganymede, or Pluto. The first mission to land on an ocean world, an airless ocean world, uh, will be the template for, for many of the ocean worlds. This conference, uh, unfortunately [laughs], due to a global pandemic, uh, had to be canceled. Uh, but we're hosting a two-hour virtual presentation of the, of the mission concept on May 14th. [00:17:00] Uh, we were just thrilled to see how much excitement there was in the number of people that registered for the initial conference and the number of people that are signing up to, uh, to listen to the, the latest, uh, in the development of the Europa Lander mission concept.

So, it really is a, a roller coaster when you look at the ups and downs of these, these mission cycles. And oftentimes the, the scientific community doesn't wanna do one thing, they wanna do a different thing. But one of the things that we're finding is that when it comes to the search for life within these alien oceans, the microbiologists, the oceanographers, uh, a whole new sector of the scientific community is getting engaged with planetary science and astrobiology. And that's, that's a really powerful kind of scientific transition.

Normally when we think about planetary science, we think about a field full of remote sensors of, of [00:18:00] people that are used to flying by worlds and analyzing pictures captured from afar, and, and spectra captured from afar. Obviously Mars has made a bit of a transition and Mars has become a real world for geologists. Uh, earth geologists love to work on Mars now because we've got in-situ robotic capabilities. But when it comes to landing on Europa or Enceladus or any of these worlds, we're seeing a lot of excitement from the earth oceanographic community and microbiologists and cryosphere scientists, et cetera, because it, it represents this possibility of getting down to the surface and really understanding the physics, the chemistry, the biology, and, and so on and so forth.

Mat Kaplan: More of Kevin Hand is coming right up, including his speculations about what intelligent life under the surface of an ocean world might look like. By the way, that virtual conference Kevin mentioned, we've got the link on this week's episode page [00:19:00] at

Kate: Hi, this is Kate from the Planetary Society. How does space spark your creativity? We want to hear from you. Whether you make cosmic art, take photos through a telescope, write haikus about the planets, or invent space games for your family, really any creative activity that's space related, we invite you to share it with us. You can add your work to our collection by emailing it to us at [email protected], that's [email protected]. Thanks.

Mat Kaplan: Understanding the Biology. I wanna jump to another section of the book where you talk about habitability, and also about, uh, the origin of life. We, of course, we don't know how that happened on this planet, much less someplace like Europa, or Titan, or Enceladus, if it's there at all, and you say some fascinating things. For example, that habitability, knowing that a world is or was at some point someplace where [00:20:00] life as we know it in those quotes, uh, might have existed, could have existed, tells us very little about whether a world could have supported the origin of life. Wha-what did you mean?

Kevin Hand: That's right. This is a very important distinction, and it really is at the kind of heart of our search for life beyond earth. One of the most fundamental questions that, uh, lies at the heart of whether or not we live in a universe in which biology is everywhere or in which life on earth represents some sort of biological singularity is this issue of whether or not the origin of life is easy or hard. We don't yet know the answer to that question. If the origin of life is easy and that it arises under a multitude of conditions in a multitude of ways, in a multitude of, of places, then I think we will go to these, uh, alien [00:21:00] oceans and potentially find life there and maybe find life on Mars, et cetera. Uh, and we will discover that we live in a biological universe, one in which life arises wherever the conditions satisfy what is needed for the origin of life.

Conversely, if the origin of life is hard, in other words, if the origin of life on earth required a very, very specific set of conditions, um, say a tide pool on the shores of an ancient ocean, or a very specific set of reactions to take place in a deep sea hydrothermal vent, then we might see that the origin of life itself is quite rare. And we might go to worlds like Europa, and Enceladus, and Titan and find that there is no life there, even though those worlds could be habitable for life as we know it. In other words, we might be able to take some life there and it [00:22:00] could survive in the oceans, but it would not be a good place for the origin of life itself to occur. So, habitable does not necessarily imply inhabited in part because of the bottleneck of the origin of life itself.

Mat Kaplan: Just a few days ago on this program, we, we featured a conversation with, uh, uh, Penny Boston, a colleague of yours, astrobiologist.

Kevin Hand: Mm-hmm [affirmative]. Yeah. [laughs] Penny, well-

Mat Kaplan: And, uh, Jim Green, NASA chief scien-, yeah.

Kevin Hand: Uh, excellent.

Mat Kaplan: We talked about biosignatures and, you know, figuring out how we're gonna recognize life that might be staring us in the face with just, something Penny has thought a lot about. Clearly you have as well, judging from the book, another pearl of wisdom from your book, s-, is, uh, at least paraphrased, if not quoted, as this, "Don't ask what life is, rather what it does when you're looking for it."

Kevin Hand: Mm-hmm [affirmative]. Tha-that's, that's right. [laughs] And the, um, at the most unglamorous, uh, [laughs] of levels, uh, we can sort of think [00:23:00] about biology, uh, as being a layer on top of geology. And what I mean by that is that biology alleviates chemical disequilibrium in the environment, mathematically speaking, physically speaking. What we've learned from life on earth is that life harnesses the negative change and gives free energy [laughs] in the environment.

Mat Kaplan: Huh?

Kevin Hand: That's a bit of a mouthful-ful, but basically what, what it means is that, uh, from microbes to blue whales, the metabolisms of everything on earth depends on finding some sort of geochemical or photochemical battery from which, uh, the business of life can harness the energy to, to get that business done. And so, yeah, I spend a fair amount of time in the, in the book detailing, uh, what life does and what life leaves behind as relics of what it does.

Mat Kaplan: By way of saying life kind of runs uphill. I mean, [00:24:00] e-e-e-entropy be damned. [laughs]

Kevin Hand: Well, now, now to be clear, so, so, uh- [laughs]

Mat Kaplan: You, you, you can't escape it. I, that's a mistake. Sorry about that.

Kevin Hand: That's, uh ... No, no, no, but, but it's a, that's a good distinction. [laughing] Uh, uh-

Mat Kaplan: Locally and temporarily entropy be damned. [laughs]

Kevin Hand: We-well, an-and the, uh, li-life is always, uh, aiding the universe in the production, uh, of entropy.

Mat Kaplan: [laughs]

Kevin Hand: Uh, but, uh, as my friend and colleague Everett Shock likes to say, um, uh, life finds these reactions. It's a, it's a, uh, a lunch you get paid to eat. Um-

Mat Kaplan: [laughs] Love that line.

Kevin Hand: Yeah, in other words, uh, it's, uh, energy that's stored in the environment that wants to be released, but it's sort of inhibited due to both physical and, and, and, uh, chemical limitations. But biology, in part by merit of enzymes that evolve and, and enhance the, the pace of reactions, biology can, uh, for example, increase the rate at which your car rusts. Um, [00:25:00] microbes can, uh, can take care of that reaction faster than mother nature can.

Mat Kaplan: You know, I keep looking for escapes from, uh, thermodynamics, but I guess there's just no escaping entropy.

Kevin Hand: [laughs] That's right. Second law will always rule.

Mat Kaplan: The other statement that you make that correlates with this is that metabolism, you claim is kind of the why of life. I mean, the meaning of life, uh, maybe not that far, but the why.

Kevin Hand: Right. And, uh, this is a, a question that many in the astrobiology community and the geobiology community ponder, uh, what is it that life does? Uh, is it, uh, did the origin of life arise from sort of a metabolism first, uh, geochemical impetus where, uh, there were these reactions just waiting to happen, and, and earliest life was just, uh, a, a bit above ge-geochemistry? And I think when it comes to life as we know it, that is the case. [00:26:00] But let's for a moment think about AI or, or extraterrestrial intelligence of a, of a form that we, we can't necessarily imagine. It's not clear to me that they would be limited to that same definition of life, where, where l-life alleviates chemical disequilibrium in the environment and so on and so forth.

Mat Kaplan: Mm-hmm [affirmative].

Kevin Hand: And there again, that's part of why I think the search for life in our own solar system's backyard within these alien oceans, uh, has the potential to, to yield such profound insights. All life on earth is based on the same DNA, RNA, protein, ATP paradigm. If we do indeed find a second independent origin of life in these distant alien oceans, might it run on some different biochemistry? Might there be some different game in [00:27:00] town? And what might that tell us about what life is? Uh, we, we don't have a good answer to that question of what is life at a universal level? And it's my hope that maybe there's a, a periodic table out there in our universe.

Mat Kaplan: Yes.

Kevin Hand: Some great tree of life that allows us to, to compare and contrast different modalities of life from which, just like the chemist did with our own periodic table, from which we can start to distill out the universals of life.

Mat Kaplan: And you even provide your own little prototype for this periodic table of life. It's a lot more complex than the one that we're-

Kevin Hand: [laughs]

Mat Kaplan: ... familiar with. It's 3D for one thing.

Kevin Hand: Yeah. And, uh, I, uh, [laughs] in the book in the, that, that chapter towards the end of the book, uh, try and kind of extend my own creative, uh, capabilities to think [00:28:00] about, uh, what that periodic table of life or that great tree of life might look like. And, uh, and I can only do so much given the information that, uh, we have available to us here on earth. But part of, again, what makes this exploration exciting is the prospect of, of putting some data to this question of, of what it takes to get life done, what biology is, and, and whether or not biology works beyond earth, and what that tells us about what life is.

Mat Kaplan: I'm gonna come back to that more speculative, uh, closing of the book or last couple of chapters in the book, 'cause that, maybe that's the science fiction fan in me. But, uh, before we do that, I mean, there really is only been one mission that overtly we sent out from our home planet to look for life so far. And it's one of my favorites. Could ... And you talk about it too. Could you talk about the lessons of Viking?

Kevin Hand: Oh, absolutely. The Viking missions, two, the two landers down to the surface coupled [00:29:00] with two orbiters, uh, circulating Mars. Those missions, uh, in my opinion, are like the, the robotic counterpart to landing humans on the moon.

Mat Kaplan: Hmm.

Kevin Hand: Uh, and what I mean by that is that they were just so far ahead of their time. [laughs] You know, it's a, it's an incredible achievement. Um, and so the, the Viking missions were tasked with looking for signs of life on the surface of Mars. The-they were doing those experiments in 1977, uh, 1976 on up through the, the sort of mid to late '70s. And think about it, we didn't even know about hydrothermal vents until 1977. It wasn't until the mid to late 1970s that we began to understand that third major branch, the archaea, uh, in our own tree of life. So much was happening in the realm of biology and just understanding our own tree of life here on earth, and yet [00:30:00] these missions were, uh, were searching for, uh, life on Mars, and they didn't find anything.

Now, one of the limitations of, of the search for, for signs of life on Mars with, with the Viking missions, was that most of the experiments were searching for living life. The Viking robotic landers were actually pouring soil and agar, sort of a salt and sugary mixture together to see if we could monitor microbes exhaling and consuming the gases in a little chamber. And nothing definitive was found.

We now know that a better way to search for life is actually to look for the relics of life, the, the large organics or other compounds. You know, in the case of, of life on earth, that's things like amino acids, and fatty acids, and lipids, et cetera, that, that are associated with the structures of life. Uh, we don't really look for living microbes.

And so we've [00:31:00] learned a lot since those days of the Viking missions, and, uh, the Europa Lander mission concept, uh, the Dragonfly mission that was selected to go out and search for signs of life on Titan, a flyby mission that would potentially search for signs of life in the plumes of Enceladus. All of those missions, uh, leverage a lot of what we learned from the Viking missions and what we've learned in the field of biology in the decades since.

Mat Kaplan: I'll note that you're on the Dragonfly mission team, uh, right?

Kevin Hand: Oh, it's an incredibly exciting mission. Yes. I'm a co-eye on that, uh, PI'd by Zibi Turtle, uh, out of the applied physics laboratory at Johns Hopkins University. Uh, I can't wait until the mid 2030 is when, uh, when that mission's gonna parachute down through the, the atmosphere of Titan, and that rotorcraft is gonna fire up and, uh, and set, uh, down onto the surface of Titan, looking at the sands of Titan, looking for organics and any biosignatures on Titan. And then, uh, [00:32:00] hop along to different sites and, and give us just an unprecedented view of that, uh, bizarre, uh, world that, that I think is perhaps the best place to search for weird life in our solar system. In other words, life that uses completely different chemistry from the water and carbon based chemistry that we know and love. And the, uh, we hypo- ... Uh, that takes place here on earth, but also is a good model for what we think might be happening within the ocean of Europa and Enceladus.

Mat Kaplan: Life as we don't know it. And I, and I'll tell you somebody else who's a big-

Kevin Hand: Yeah.

Mat Kaplan: ... fan of that mission because he, he brought it up, uh, um, mm-mm-mm, about a month ago as this has heard, uh, the NASA administrator Jim Bridenstine, who was pretty thrilled by, uh, the Dragonfly mission. Before we run out of time, I want to run back to the, the, those closing speculations of yours, at least some of them. Uh, there's so much we won't have time to cover here. Let's say that that Europa Lander, that you're, that you're advocating for, uh, [00:33:00] lands and sure enough, finds some pretty complex molecules, organics on the surface of that moon, that lead us to believe that something is swimming around in that ocean down below. Now moving into your speculations, do you believe that those oceans, uh-uh-uh, if we had something that melted its way through the ice and went down there, that, would you be surprised to find that it was more than microbes, that maybe we'd find multicellular life?

Kevin Hand: [laughs] Well, as you know, I love this question and, uh, uh, [laughs] and to be-

Mat Kaplan: I suspected.

Kevin Hand: [laughs] To, to be clear, I would be, uh, [laughs] through the moon to use an appropriate-

Mat Kaplan: [laughs]

Kevin Hand: ... phra-ph-phrase with, uh, with finding even the, the tiniest of microbe on a, on a, on or within a, a distant alien ocean. Uh, because such a, a, a discovery would, uh, revolutionize our understanding of biology. But [00:34:00] specifically with the case of Europa, there's a really interesting dynamic going on, and that is that the surface ice of Europa is being bombarded by charged particle or radiation from Jupiter's magnetosphere. And make no mistake, the engineers, uh, don't like that radiation because it poses problems for robotic vehicles. But when it comes to the chemistry of Europa, and perhaps the chemistry of Europa's ocean, what we see spectroscopically on Europa's surface is condensed phase oxygen, O2, uh, hydrogen peroxide, sulfate, a bunch of, uh, a bunch of compounds that are made as these charged particles split apart water and some of the O recombines into O2, and OH, uh, combines with, uh, OH to make H2O2 for oxide, et cetera.

And if some of those oxidants, if some of that oxygen makes it into the ocean below, [00:35:00] now you might actually be charging up that ocean with enough chemical energy to potentially give rise to multicellular life. All we have to do is look at the evolution of life on earth, uh, and, and see that it, it was really the rise of oxygen in our own atmosphere made possible by photosynthesis, by, uh, cyanobacteria pumping oxygen into our atmosphere. That abundance of oxygen helped drive the evolution towards multicellular life, and, and that's what drove the, the Cambrian explosion, which of course then led to, uh, uh, to us and all of these large creatures.

Well, on Europa, photosynthesis is not likely a viable niche given that its ocean is beneath a relatively thick ice shell of at least a few kilometers or so. But this radiation produced [00:36:00] oxygen might allow for multicellular life to, to exist there. And so, uh, yeah, in the book I've got a chapter called The Octopus and the Hammer, where I, I look at, um-

Mat Kaplan: [laughs]

Kevin Hand: [laughs] ... at, uh, what could play out in an oxygen rich alien ocean. Uh, and it's a lot of fun speculation, but there's, uh, there's enough tethers there to, uh, to real data that, um, that I think it's, it's fun worth pondering.

Mat Kaplan: All right. Then you push the envelope even further because if there's enough, if there are enough nutrients, if there's enough of that free O2, could intelligence have evolved down there? Tell me about your, uh, hydrothermal vent farmers.

Kevin Hand: [laughs] Uh, you did read, yeah, you read the whole book. [laughs] Exactly, so you got all the-

Mat Kaplan: I read the whole book. [laughs]

Kevin Hand: Um, so yeah. Th-these, uh, these are the things I think about late at night, Mat. And, uh ... [laughing] So, [00:37:00] yeah, you just play out the, um, the kind of evolutionary scenario of, of tens of millions, hundreds of millions, perhaps even billions of years of evolution without the limitation of, of chemical energy. Imagine that oxygen is freely available in that ocean and that perhaps you do end up giving rise to some sort of octopus or cuddle fish like creature that, uh, uh, develops a form of intelligence and problem solving, and perhaps even tool use. And then think about what it would mean for that creature to, uh, to survive in the depths of this alien ocean. And so I go into some detail about how those, uh, those deep ocean creatures would probably gain a good understanding for the, the sea floor dynamics and where the chemistry is erupting out of the sea floor in a [00:38:00] manner somewhat similar to Oasis in the Sub-Saharan Africa where water was made available and other compounds that, that life needed was made available. So you might have these oases on the sea floor that form the, the epicenter for these, uh, colonies of intelligent creatures.

And a-again, as you know, part of what, uh, what I explore in that chapter is what does it mean to be an intelligent creature in a deep dark ocean? Uh, what does it mean to, to not be able to look up and see a night sky?

Mat Kaplan: Mm, mm-hmm [affirmative].

Kevin Hand: Uh, how, how would those creatures think about the universe in which they live? A universe, which is an ocean, a global ocean that they perhaps can explore in many different ways. But instead of seeing stars above, their universe is capped [00:39:00] by an ice sheet, an ice sheet that creaks and cracks. They don't have the cosmos compelling them to explore beyond their world. And I really think that's an interesting thought when you consider what has motivated our innovation, what has motivated our exploration as Australopithecus on up to homo sapiens. The night sky has always called us, uh, and has motivated our march across horizons and, and out into the cosmos. Would creatures within Europa or Enceladus or these alien oceans have a, have a similar calling?

Mat Kaplan: I think it would be our moral obligation to introduce them to, uh, to the universe. [laughing]

Kevin Hand: I like that. Uh, I like that train of thought. Uh, hopefully they are altruistic, intelligent creatures that, uh, have figured out many of the things that we, uh, still, uh, stand to, to learn [00:40:00] when it comes to, uh, a longterm sustainable civilization that, uh, has developed technologies but not always the, the most peaceful of technologies.

Mat Kaplan: Well intelligent or not, finding life elsewhere, uh-uh, would certainly teach us a lot. We're the Planetary Society. We believe the public is thrilled by the search for life off of this world. Uh, we know our members are, and certainly you are too. Do you wish we were moving faster?

Kevin Hand: Oh, absolutely. It's, um, you know, I'm, I'm working day and night trying to, uh, to get these things moving and then, uh, I'm incredibly appreciative of, uh, the Planetary Society and all its members. There's nothing technologically keeping us from moving forward with these, uh, these, these great missions, these, these missions that, uh, aim to achieve civilization, scale science, uh-uh-uh, probing questions like, are we alone? Uh, is there life beyond Earth? [00:41:00] Really the only limiting factor is, is sort of a, a large committed vision, uh, to, to help us move forward with this. An-and so, uh, to the extent that, that you and others are helping to, to get that vision out there, we're, we're greatly appreciative.

Mat Kaplan: We'll keep doing our part. Uh, Kevin, I warned you that I would ask you to read the last couple of paragraphs, uh, in this book. Uh, have you got it handy?

Kevin Hand: Oh, sure. I'll, I'll dive right in here. "Perhaps we are the only ones. Perhaps the origin of life is hard, and life is rare. Or perhaps we live in a universe teeming with life, a biological universe of incredible diversity across planets, moons, stars, and galaxies. Perhaps our tree of life, the singular center of biology as we know it, is revealed to be but a tiny twig, on a [00:42:00] tiny branch, joined to a vast and grand tree of life, connecting the beauty of all life in the known universe. Looking up at the night sky, seeing Jupiter as a bright point of light above the horizon, I can't help but wonder whether our return to that beautiful planet and its magnificent moons will once again catalyze a scientific revolution in our understanding of our place in the universe. Europa, and the many alien oceans of our solar system, await."

Mat Kaplan: Beautiful.

Kevin Hand: Sound good?

Mat Kaplan: Oh, you passed the audition, Kevin. Thank you for that.

Kevin Hand: [laughs]

Mat Kaplan: Lovely quote. Um-

Kevin Hand: Oh, thank you.

Mat Kaplan: Thank you for this book and for this ... I knew it would be a fascinating conversation and, uh, i-i-if it isn't obvious, I highly recommend the book, Alien Oceans: The Search for Life in the Depths of Space, available now from Princeton University Press and all the [00:43:00] usual places. And, uh, my guest has been astrobiologist and planetary scientist at the Jet Propulsion Lab, Kevin Hand. Kevin, I thank you again and I, I look forward to, uh, talking again.

Kevin Hand: Thanks so much, Mat, and I appreciate your time and, and all the time that the Planetary Society and its members do to help, uh, explore the cosmos.

Mat Kaplan: Stay tuned for your chance to, uh, win Alien Oceans in What's Up, which is coming up right now. Time for What's Up on Planetary Radio. So we're joined once again by the chief scientist of the Planetary Society. He's also the, uh, manager of the LightSail program for us, and, uh, he'll be telling us about the night sky in a moment. Uh-uh-uh, welcome back. I, I wanted to let you know, I've heard from a whole bunch more people who really enjoyed What's Up Live, the, the first, uh, installment of a Planetary Society Live that people can find at They can see the, uh, the past performances there, including our, uh, our [00:44:00] season opener, our premiere of that series.

Bruce Betts: Excellent. That's good to hear.

Mat Kaplan: And they're wondering when we're gonna do it again. We, and the plan is that we will, we just don't know exactly, [laughs] the exact date yet, but I don't think it will be long. Maybe two, three weeks.

Bruce Betts: Yeah.

Mat Kaplan: We'll, we'll let you know. Stay tuned. And, and as you stay tuned, Bruce can tell us about the night sky.

Bruce Betts: In the evening sky, Venus is running away. It's low in the West, still super bright, marching downwards in the sky [laughs] from night to night rather rapidly at this point. Uh, on May 21st, the evening of May 21st, it will be hanging out near the much dimmer, but still pretty bright, Mercury, making it one of its Mercurian presences known. I was not [inaudible 00:44:44]. I mean, see them close together on May 21st, but you need a pretty clear view to the Western horizon. In the dark predawn sky in the East moving Southeast, you can check out three planets we've got from lower [00:45:00] left, reddish Mars getting brighter over the coming weeks and months, yellow Saturn, and bright Jupiter, Mars and Saturn, and Mars kind of moving away from the other two. It's good. It's good. Are you good, Mat?

Mat Kaplan: I'm good with that

Bruce Betts: Then we're good to go on to this week in space history. 1963 was the final flight of the mercury program with, uh, Gordon Cooper launching in Faith 7. And in 2009 the final Hubble Space Telescope servicing extra vehicular activity spacewalk to add more goodies to the Hubble Space Telescope.

Mat Kaplan: [laughs] Which is, uh, gonna come up again I think next week. Isn't that when you're gonna answer your, uh, trivia question about, uh, how much more, how much more massive is, uh, the Hubble now?

Bruce Betts: Yes. And in the meantime, I've got a Hubble Space Telescope [inaudible 00:45:58]. [laughs]

Mat Kaplan: Sprung [00:46:00] that one on us.

Bruce Betts: Surprise. Hubble Space Telescope was originally designed, it was designed from the start to be serviced by astronauts in space, including being equipped with over 300 feet of EVA handrails, and 31 portable foot restraint sockets.

Mat Kaplan: [laughs] I don't know, for some reason when you said portable, I, I suddenly thought, "Oh, they put a porta potty on it?" But uh, you know, we were talking about toilets on the ISS a week or two ago.

Bruce Betts: [laughs] Uh, dang it, that was gonna be on my trivia question.

Mat Kaplan: [laughs]

Bruce Betts: How many, how many toilets are there on the Hubble Space Telescope?

Mat Kaplan: [laughs]

Bruce Betts: You ruined it. Now you've diverted us completely. Let's move on to the, uh, trivia contest. But seriously folks, in the trivia contest, I asked you, whose silver astronaut lapel pin is on the moon? How did we do, Mat?

Mat Kaplan: The, [00:47:00] uh, number of entries really rebounded this week, perhaps because people wanted that, uh, beautiful print by space artist, Michelle Rouch. It's of Neil Armstrong. Uh, very appropriately of that pioneer on the moon. This one was not on his mission. It wasn't Apollo 11. Go ahead. Tell us, tell us how this happened and what happened.

Bruce Betts: Apollo 12 was supposed to be scheduled as the lunar module pilot was Clifton Curtis "C.C." Williams Jr., and unfortunately he was killed in a 238 crash caused by mechanical failure. He was replaced by Alan Bean, and Alan Bean, uh, took Clifton Curtis "C.C." Williams', uh, silver astronaut pin as well as his Naval aviator wings and placed them on the lunar surface in his honor.

Mat Kaplan: It's quite a story. We heard from a number of people about Alan Bean, uh, I'll get back to a couple of them in a moment, but our winner this time, Thomas [00:48:00] Fisher, first time winner. Thomas, uh, we're gonna send you that limited edition print by space artist, Michelle Rouch and you can check her out online. It's R-O-U-C-H. She has a gallery, great work. Robert LaPorta in Connecticut, he says he was lucky enough to me-, have met Alan Bean more than a few times and he has some of his paintings, uh, because Alan of course became quite an artist. Have you seen some of his work?

Bruce Betts: Yes. Oh, it's, it's, uh, cool, combining space with art, having actually been out there.

Mat Kaplan: Robert also said he was a true gentleman. Tim Livingston in Oklahoma says, "In December of 2015, I was fortunate enough to attend an event at the Oklahoma History Center celebrating the 50th anniversary of Gemini 6A and Gemini 7. Alan Bean along with Jim Lovell, Tom Stafford, and Buzz Aldrin were the featured guests. I learned that evening that Alan Bean was key in saving two missions." You probably know about this, right? This is the one where I, I guess he threw a switch, [00:49:00] uh, on Apollo 12 SCE to AUX and saved that, um, that mission from an abort I think?

Bruce Betts: Yeah, I believe that was after they were struck by lightning twice on launch. But maybe I'm wrong. I mean, I know they were struck by [laughs] lightning twice, but I can't remember the details of the story of recovery.

Mat Kaplan: I'm pretty sure you're right about that. Uh, but then, apparently Alan Bean was also serving as the caps-, uh, Capcom, the capsule communicator, for Wally Schirra and Tom Stafford in their Gemini capsule. He, um, told them, "Don't abort. Don't pull that D-ring because," or at least he did, he didn't tell them to do it, and they decided against it as well and, uh, that became a successful mission instead of [laughs], uh, a test of the emergency escape system.

Bruce Betts: Do we have an emergency eject system?

Mat Kaplan: Yeah, it's right underneath your desk there. Don't pull it. Don't pull the D-ring. There's no need right now.

Bruce Betts: Oh, okay. It's good to know it's there though.

Mat Kaplan: [laughs] It's reassuring, isn't it?

Bruce Betts: [00:50:00] It is.

Mat Kaplan: Just, uh, just leave it alone. [laughs]

Bruce Betts: All right.

Mat Kaplan: Pavel, uh, recently a winner. Uh, Pavel in Belarus said that, uh, later, later after A-Apollo 12 returned, Alan Bean said about it, "I often think of my silver pin resting in the dust of surveyor crater just as bright and shiny as it ever was. It will be there for millions and millions of years, or until some tourist finds it and brings it back to earth." [laughs] Wait, there's more. Jim Bridenstine gave the following advice to the 22nd astronaut class graduates, Bridenstine of course the NASA administrator, "If one of you are on the surface of the moon and you do find one of those pins, if you leave it there, we'd really appreciate it."

Bruce Betts: [laughs] Well, okay. I guess they have their orders.

Mat Kaplan: That's it. We're ready to move on.

Bruce Betts: All right. Those who are noticing the Cygnus cargo spacecraft NG-13 was recently released from the International Space Station. Who is it named after? Go [00:51:00] to, and don't say it was named after NG-13. I'm looking for, for an actual-

Mat Kaplan: [laughs]

Bruce Betts: ... uh, a different name.

Mat Kaplan: You heard him, you've got until the 20th, that'd be May 20th, Wednesday, at 8:00 AM Pacific Time, to get us this answer. And, and this is the best part, win yourself a copy of Kevin Hand's brand new book, which we were just talking about, Alien Oceans: The Search for Life in the Depths of Space. Uh, and you can also get the, uh, the audio book version of that, and, uh, hear it read by, uh, by Kevin himself. It is published by Princeton University Press. Terrific book. I think we're done.

Bruce Betts: All right, everybody. Go out there, look up the night sky and ponder whether you could make a chain link fence out of sausage links. Thank you. Goodnight.

Mat Kaplan: [laughs] That's, uh, Bruce Betts, the chief scientist of the Planetary Society, clearly running out of things to do as he shelters in place. [laughing] Wouldn't keep the dogs out, I can tell you that.

Bruce Betts: [laughs][00:52:00] Yeah, I don't think it'll last long.

Mat Kaplan: Hey, I-I'll leave you with this. Listener Sean Schultz in, uh, Pennsylvania, "In this time when we must remain distant, may the cosmos bring us together."

Bruce Betts: That's quite lovely. Good sentiment.

Mat Kaplan: Thank you, Sean, and, uh, thank you, Bruce. Talk to you next week.

Bruce Betts: All righty.

Mat Kaplan: That'd be when he's back here for the next edition of What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its carbon-based members. Come on in, the water's fine, at Mark Hilverda is our associate producer, Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. Please help us out with a rating or a review in Apple Podcast. Stay well and ad astra. [00:53:00]