Planetary Radio: Space Exploration, Astronomy and Science - What’s Next for Mars Exploration?

Episode Date: December 25, 2019

The Red Planet is slowly revealing its deepest secrets, but there’s much more to learn. The biggest mystery is whether it has ever been home to life. Caltech and JPL planetary scientist Bethany Ehlmann lays out the path ahead in a fascinating conversation. The holiday night sky is alive with stars, planets and even a meteor shower. Bruce Betts will tell all in What’s Up. Our last episode of the year opens with space exploration headlines from the Planetary Society’s news digest, The Downlink. Learn more and enter the space trivia contest at https://www.planetary.org/multimedia/planetary-radio/show/2019/1225-2019-bethany-ehlmann-mars.htmlSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

The Future of Mars Exploration with Bethany Elman, this week on Planetary Radio. Welcome, I'm Matt Kaplan of the Planetary Society, with more of the human adventure across our solar system and beyond. Happy Holidays everybody. That old red planet hangs over our heads like an ornament on a cosmic tree, delighting and challenging us to reveal its remaining secrets. And there are many of them. We'll talk with planetary scientist and confirmed Martian Bethany Ellman about these mysteries and the path that is taking us toward solving them. Our second present is another visit with Planetary Society Chief Scientist Bruce Betts,

who will bring us this week's What's Up. It has been a busy time for space exploration, and the latest edition of the Society's News Digest, the Downlink, is chock full of goodies. Here's a sampling. By now you've probably heard that Boeing's Starliner didn't quite reach the stars or the International Space Station, the uncrewed test was otherwise very successful. It became the first American capsule-style spacecraft to soft land on solid ground. An odd onboard timer error seems to have been the only

major problem with the mission. The astronauts who may fly in a starliner before long believe they might have been able to fix the error and make it to the ISS. You just can't keep those humans down, can you? The International Astronomical Union released the results from an international campaign that allowed people in nations around our planet to propose names for over 100 stars and exoplanets. I particularly like Krotoa, which is the new name given to a gas giant world by South Africans. NASA's Mars 2020 rover that we will talk about with Bethany went for a drive last week. It all happened in the big clean room at JPL, which is where Emily Lakdawalla and I will be visiting it in a few

days. The rover didn't seem to mind driving in three times the gravity it will deal with at its destination. No complaints anyway. The Planetary Society's editorial director, Jason Davis, brings us the downlink each week. Though Jason will be taking a well-earned break on the last Friday of 2019, you can check out the complete latest edition at planetary.org. Bethany Ellman arrived at the California Institute of Technology in 2011. She had already gained an impressive reputation as a planetary scientist, coming at that broad discipline from the geological angle. She became a Jet Propulsion Laboratory research scientist a couple of months later. As you'll hear, she is or has been a participant in many missions of exploration, with more in store, including the coming year's 2020 rover that will soon have a more romantic name. Bethany recently joined me from her Caltech office for a look ahead at what we hope to learn about Mars in the coming years

and how we hope to make those discoveries. Bethany, I am very happy to welcome you to Planetary Radio. Actually, to welcome you back, you have been heard on the show before, radio, actually to welcome you back. You have been heard on the show before for this conversation about what's ahead or what ought to be ahead on the red planet, on Mars. Thanks for joining me. Delighted to be here, Matt. I know you've taken a look at this article, great article in the current issue, current as we speak, the December solstice issue of the Planetary Report by your colleague, Javier Gomez-Alvira, Planetary Report by your colleague, Javier Gomez-Alvira, titled What Comes Next on Mars?

And I'm hoping that can be, as I said, the theme for our conversation today. But before we look at the future, I want to go back. We could go back even further, but let's start with 1976. I was at JPL reporting for my college radio station when Viking 1 soft landed on the Red Planet. Are you as awestruck today as I have always been by what the Viking mission at least attempted to do more than 43 years ago? Especially in retrospect, Viking is a huge accomplishment because, frankly, landed missions to Mars fail more often than they succeed. That's a historical fact. And, you know, we still haven't always nailed it, although we've had a great string with the most recent set of NASA missions. So first of all, that Viking got there not once, but twice is spectacular. And especially, you know, given how long that was ago and at what's such an early stage of planetary exploration. And so it changed forever, really, how we think about Mars. And yeah, maybe the life detection experiments would be more sophisticated today, but it was those first steps on Mars. What a courageous, valiant attempt.

And I still marvel at the little laboratories, robotic laboratories that they packed into that spacecraft all those years ago. That's right. They had some very ambitious experiments, including x-ray spectroscopy, some mass spectroscopy, and then these effectively wet chemistry experiments did autonomously. Pretty amazing. A lot has happened since then, obviously. What do we know now about Mars that we didn't when that golden age of Mars exploration got underway, if you want to mark it from that point? And go ahead, you can take the next hour to talk about this. Just kidding. Happy to. I could keep talking for about that long. The last decade, well, really the last

two decades since the Mars Global Surveyor mission in 1997, we're really living in a golden age of Mars exploration right now. And our view of the red planet has forever changed. And what we know is just at an exquisite level of detail. That said, we don't know everything. And there are big questions about ancient climate change, modern climate change, and whether or not there's life on Mars. That question is still out there. Well, that is the dominating question, right? Whether we're going to be able to find evidence of past or present life. But if we ignore that overriding question, what are the other big unknowns about Mars that you still want to see answered in the missions to come? I agree. The search for life on Mars is one of the exciting things that we as humans can do with our space program. And I agree, that's a great question to pursue. Actually, though, I think there's an almost equally important question at Mars. And that is the question of why did Mars change from a once habitable planet to the cold, dry, if it's

habitable, it's like teetering right on the edge planet that we have today. Because if you look back in the ancient rock record of Mars, if you were able to transport yourself magically in the way back machine to the surface of Mars three and a half billion years ago, you would likely find yourself standing on a planet with water. Mars had lakes, it had rivers, it had hydrothermal systems, soils were forming, and a whole host of environments that you recognize here on Earth and that if they, on Earth, they would be inhabited with life. And so the question is, not only did those environments have life, but also why did Mars change so profoundly? What happened? And what does that

say about how planetary habitats are rare or common or short-lived or long-lived in the universe? Aren't we closing in on that? I mean, we've had conversations on this show with people on the MAVEN mission and others. I mean, we're beginning to get what happened up there, right? Where all the air went and where the water went too, for that matter. Yeah, I think we're beginning to understand it. And I think there are still some important gaps. Let's see, here are two gaps, things that we do not understand. Mars is further away from the sun than the earth, right? So actually, in order to make Mars warmer, you have to have about 60 or 70 degrees Celsius of greenhouse warming. That's a heck of a lot more than earth. I don't know the earth's number right off the top

of my head, but it's something closer to 20. We're closing in though. Yeah, well, but what we're talking about, just so your audience appreciates it, what we're talking about with what we as human beings are unfortunately doing to the climate of our earth, what we are talking about there is two degrees Celsius is the change, the dangerous change that we're talking about that can be a climate tipping point. What I'm talking about with Mars is that we need about 60 or 70 degrees of greenhouse warming relative to, you know, just what it would be in equilibrium with the amount of light it's receiving.

That's a huge amount of greenhouse warming. And they're really, in spite of 50, 60 years of thinking about the question, no one's hit on the hit on an answer that's consistent with everything. Like, how was there liquid water on the surface of Mars at all? So we're getting closer because maybe Mars wasn't always warm and wet. Maybe it was cold and wet. But that's still a huge question hanging out there. And then the other question hanging out there is why does water seem to come and go?

So, yeah, we lost the atmosphere. But if you back calculate the Maven rates, we don't quite lose enough atmosphere. Assuming that magically it was this thick greenhouse warmed atmosphere. Anyway, we don't quite lose enough if you use the Maven rate. So something else had to happen too. So we're getting there. We're like that old adage about sort of feeling different parts of the elephant. The climate modelers are working on their side, the geochemists are interpreting the rock record, and we're all trying to put the pieces together to make the story. But I think that story about climate and habitats is another big one.

Are some of these missions that are going to be heading toward the red planet in the next few years, are they going to help us to answer these that you've just posed? Yeah, absolutely. Both of the missions are really important because they're going to the ancient parts of Mars

and they're going ultimately after the life question, and also after the climate change is preserved in the geological record. So Mars 2020 will be headed to Jezero Crater, an ancient former lake basin, and then just outside of it are some ancient hydrothermal systems that are even older. So hopefully we'll have a chance to take a look at both of those environments. And importantly for Mars 2020, collect samples to bring back to Earth to study with the best Earth laboratories. And then the European Space Agency also has a big rover mission slated to launch in 2020.

Both of these, both the US and the European one, land in 21. And the Rosalind Franklin rover from ESA has a drill on it. So it too will go to an ancient terrain near the northern dichotomy boundary of Mars. And there it's going to drill about two meters down, pull up materials and look for signs of organics and other perhaps hints of life. This is one of the things that Javier Gomez-Ovira talks about in that article, which is called What Comes Next on Mars, that Rosalind Franklin will be able to go that far down below the surface, much deeper, I believe, than we've ever been able to get before by far,

particularly with the continuing difficulties the mole is having on the inside lander. But to be able to pull up samples, is this particularly exciting to pull them up from that far down? What's exciting about the depth that the Rosalind Franklin rover chose of two meters is that that is based on our models. It's below the depth that damaging radiation and cosmic rays penetrate, act to destroy organics over time. So that's kind of why the magic number was one to two meters, because it's predicted that at that depth, even over billions of years of being, you know, hit by radiation coming through Mars's thin atmosphere, that the organics would still be

largely untouched. They're affected aics would still be largely untouched. They're affected a little bit, but largely untouched. So that's why the ExoMars team has made the decision to go deeper. This leads me to a sidebar in that Planetary Report article called Signs of Life on Mars. And it's pretty cool. It's nicely illustrated. And I don't think I mentioned yet anybody, whether you're a member of the Planetary Society or not, the members get the paper copy of the magazine, of course, which is beautiful under of signs of life, biosignatures. Can you pull out some number of these and talk about how we might use these to find that evidence of life or past life?

So this is something that we've thought a great deal about. And I'll say this is one of the areas over the years since the Viking landers in the late 70s. This is where our understanding of how to look for signs of life has changed profoundly. Rather than trying to culture sort of Earth-like microbes by doing wet chemistry on Mars, we kind of now understand that life has a lot of varied forms and we have to piece together the clues from different directions. So there are basically six signs of life on Mars. If you wanted to be really sure that you had life on Mars, you'd want them all. But that's hard sometimes in the geologic record when you're looking at not life living, breathing in front of you, but life preserved over several billions of years and changed as a result of the rocks. So for example, the overriding evidence of

life is having organic material, right? So these are carbon containing compounds, usually with hydrogen and nitrogen and things like that, too. So that is the stuff of which life is made. And so having organics is the first great hint. Now, organics don't only form in life, they can also be synthesized by certain water and rock reactions. And we know that these took place on some of the meteorites very early in the solar system history. And so meteorites also have organics. So organics is one line of evidence, but not sufficient alone. The other good ones are what I'll call the kind of chemical fingerprints.

These can be minerals, specific chemical element ratios, or isotopes, because the processes that are used by life often, especially for microbes, leave behind traces in the mineral record. I mean, just think of plankton and foraminifera and all these things in the ocean that create shells, either of calcium carbonate, mineral calcite, or silica, right? So these solid records record the fingerprints of life and for isotopes, life tends to prefer the lighter, more abundant isotopes. So you can get these kind of signatures or fingerprints in the chemicals, the minerals, and the isotopes. Would that be related in a way to what so many of us are familiar with, with the carbon-14 dating

and other techniques like that? It's related. Carbon-14 dating, for example, uses the carbon in organic material. In this case, though, the carbon-14 has a much shorter half-life than we're probably thinking about on Mars. It's the order of, I believe, tens of thousands of years. Don't quote me on that fact-check carbon-14 dating Wikipedia, but it's something on the order of a shorter time period. So organics, isotopes, minerals, and we have found the organics. We found some at least simple ones, but that big question about whether they are biological or non-biological, it goes on from there in this list. What's the next one of these biosignatures?

Well, then the next ones are basically fossils, either small scale or large scale structures. So maybe this is what most of us actually think. Maybe I should have started there, but this is what most of us think about when we think of ancient life. We think of the proverbial dinosaur bone, which is not really bone, but the fossil cast of a bone sticking out of a rock. And so these morphologies or structures that suggested an order can be characteristic of life. Of course, you know, I mentioned minerals. Those of you who are fans of minerals know that these also have a beautiful order to them. So there are these six signs of life on Mars, but I've simplified it along kind of grouping them into organic stands on its own. There's these chemical fingerprints,

which are either chemistry minerals or isotopes. And then there's these structures or fossils, which can be small or large scale. It would certainly simplify things, wouldn't it, if we took a picture or a macro photo from the 2020 rover or from Curiosity, for that matter, and saw something that looked like a trilobite fossil? Yeah. like a trilobite fossil? Yeah. And I have to say, reading the internet about every two or three weeks or so, something pops up with some rock. It's interpreted as a fossil life or it's interpreted as a piece of an alien spaceship. But believe you me, you would not be able to keep several thousand NASA Mars scientists quiet if we had actually found life on Mars already. So we have not seen anything so obvious yet in the data. I just think about how you and all those other thousands would be jumping up and down for about a week

if something like this happened. I mean- I think it would be more like a year. More of Bethany Ellman is just ahead. I hope you'll stay with us. Bill Nye, the planetary guy here. The Planetary Society has just begun its 40th trip around the sun. That's right, it was 40 years ago that our founders created our organization. Help us celebrate four decades of connecting people

around the world with the passion, beauty, and joy of space exploration. A certain very much beloved donor will match our gifts up to $100,000. Please make your gift today and see your impact doubled. Go to planetary.org slash donate. Thank you indeed. When the news came from NASA about that famous Martian meteorite, that there were these funny little structures in there that sure looked like they might have once been alive, I was driving my car with my family. We were on vacation.

I had to pull over and do a little dance on the side of the road. But we all know that saying, right, from founder of the Planetary Society, Carl Sagan, extraordinary claims require extraordinary proof. Yeah. And so this is a really interesting story. And it's actually a perfect case to illustrate the multiple signs of life on Mars. And yes, Carl Sagan said extraordinary claims require extraordinary evidence. Because basically, we want to make sure that we get it right when we

make the life ID. Now, Allen Hills is a special case because we can talk through each of these six signs of life that we just talked about. And there is a potential case to be made that the structures that are seen in Allen Hills 84001 are life. The problem is, is it's not a unique interpretation. With a little more thought, there is a series of other scientific groups that were able to put forward another fairly reasonable explanation involving water rock reactions, creating carbon bearing compounds and also the mineral magnetite. And have, I think, explained the Allen Hills 84001 data in light of that particular hypothesis. And that particular hypothesis. And that particular hypothesis doesn't require life. But I'll say that as a scientist, one of the things that's important is keeping an open mind. Personally, having read some of the manuscripts pro and con,

I also don't think that they've disproven it is life. It's one of these things about burden of proof. Where is the burden of proof? I deal with this in court cases, but in this case, I think because it's such an extraordinary claim, the burden of proof is to prove that it's life beyond a reasonable doubt. And what's basically happened over the subsequent years is that people have introduced doubt. Yeah. Well, at least it's one piece of evidence, but one data point. It is. And the important part is also that it means there was water flowing through rocks, supplying the chemical reactions that could sustain life. So even if it turns out that

those little globules of magnetite in a chain associated with some nearby organic material, if those aren't life, it at least points to the signs and conditions that could have supported it. We've already mentioned the 2020 rover. You're on the science team for that next explorer of Mars, on the surface anyway. And you mentioned Jezero Crater as the target. Of course, we know that for years, there was that process of choosing where this rover would go. Are you pretty happy with the result? Are you looking forward to what we can find out there? So this was a site that's had a long life. This site was put forward for the Mars Science Laboratory site, and I was one of the proponents of this site for Mars 2020, along with others. I think we will learn a lot about Mars and

Jezero Crater, and we're going to a spot where we know would have for a brief period of time on Mars been habitable. Kind of like Gale crater where the rover is now. Jezero is what geologists would call a sedimentary basin on Mars, which basically means it's a big hole in the ground that collected sediments carried by water. So it once held a lake. So like Gale, Jezero once had a lake. There's this beautiful delta. If you Google Jezero Delta, I hope your readers and listeners can check it out because it's really this spectacular landform. It's gorgeous. It's amazing. It is. It is. And we also discovered back in 2008 that there are clay minerals and carbonate minerals hosted within it, some of which are good for preserving things like fossils and perhaps isotopic evidence of life.

So there's a great argument to be made to explore these lake basins. made a public case for a different landing site at the landing site workshops that were going on, because I think we need to go to an even earlier period in Martian history, earlier than the sediments that are preserved in Jezero Crater. But fortunately, what is good about this landing site is that if we are able to conduct our explorations at Jezero Crater and the rover still has some health in it. On the rover's extended mission, we can drive just 20 kilometers to reach these more ancient rocks that record a period about 500 million years earlier, and that record a set of environments in like, you know, strata, like pages in a book. And we can step through these hydrothermal and other surface environments

recorded in the strata. So I think Jezero crater is great because we can study this amazing Lake Delta environment, and then we can get out there, get onto the plateaus and go study an even more ancient period of Mars history and collect samples while doing it. Let's hope that the 2020 rover will live long and prosper like Opportunity and make that trek across Mars. That would be fantastic. Yeah. Well, like spirit and opportunity and curiosity, they have all so far outlived their warranties. We can't count on it, but so far, so good. Yeah. Fingers crossed. Um, as you talk about these things and how we pick sites on Mars, it reminds me that, uh, of course our rovers, our landers have visited far less than 1% of the planet, an infinitesimal portion. But we do have those great orbiters overhead.

And you've been involved with some of that work. Aren't you on the CRISM team for that instrument? That's right. Yeah, I'm on the CRISM imaging spectrometer team. And that's how we've been able to learn a lot about most of the, or a lot of the planet, right? From a distance. Yeah, that's right. The Mars Reconnaissance Orbiter has really been a great tool that's just blown open our understanding of the environmental history of Mars because it has this CRISM imaging spectrometer. What that means is that it collects infrared light at multiple

wavelengths so that when you look at an image, if you look at a pixel, you not only see the pixel, but you get the mineralogy, what Mars is made of at that point. over time, detecting things like clay minerals, carbonates, silica, chlorides, that all point to all different types of aqueous environments, water-rich environments all over the planet. It's always interesting to note how these orbiters work in tandem, all of the instruments on the orbiters, of course, but also how they work in partnership with the landers down on the ground. You mentioned the CTX, that's the context camera, right? Sort of the wide angle one. And then that amazing high rise camera,

which is our best eye in the sky above the red planet. Yes, six meters per pixel and 30 centimeters per pixel respectively. It's pretty darn good. Yeah, I'll say. Sample return. We know of course that even though it's going to bring some instruments and do some work there on the surface, like Curiosity, like MSL, that a big part of this mission is going to be bottling those promising samples and then hoping that they can be brought back here someday.

Are you one of those who agrees that this is sort of the holy grail for understanding Mars? I think sample return would be a huge step in our space exploration future. There's so much that we can do in our laboratories here on Earth that, amazing as the rovers are, we cannot do with rovers, nor are we likely to be able to do with rovers in the next 100 to 200 years. So there's immense value in bringing back samples from other planetary surfaces to study here. And moreover, you know, even just taking that action is also a step on the way to potentially bringing humans because it demonstrates the ability to go there and come back, which really hasn't been demonstrated before. So I think, you know, sample return is a huge step in exploration. That having been said, I don't think it's the

holy grail after which all questions will be answered. I really think looking forward to the future in terms of what needs to happen in parallel with sample return and after sample return, there are a number of key science questions and key missions that remain for us to truly explore Mars. And I can talk more about those if you want, but I think the exploration future continues. I would love to hear more about your thoughts in that area. I'm happy to talk about that because the question of, I think, whether Mars has water today or has life today is still not answered. And then even though our rovers will have been able to visit by that point, let's see if I do my math here, by that point, five have roved around.

Well, five and with ExoMars, six portions of the surface, six sites. Imagine if you could go to Earth and you only had to pick six sites. Think of everything you'd miss. Did you pick the right six sites? How do you know? Yeah, we're back to the blind men and the elephant like you were talking about. Yeah, you get different parts or different pieces of the planet by going to different areas. And so I think there's really two things that have to be done. One is that we need an orbiter mission

in the future to really drill in on the question of, is there liquid water on Mars underground today? Does it exist? We don't know. There have been hints, but I think the consensus view is we don't know if there is liquid water underneath the surface today. And that's a pretty darn big question. And then secondly, I think we really need to revolutionize our access to the Mars surface because it's becoming more and more apparent that the biggest questions to answer about past life and about climate change require the types of measurements of organics and isotopes and chemistry that you can only get from landers and rovers. But to be able to afford it, we really need to revolutionize our ability to access the Mars surface in a different manner.

Do you foresee the possible missions, maybe way down the line, maybe the late 2020s or even beyond, where we might be able to send robots with the kinds of capabilities you're talking about? I think so. I mean, we have these capabilities today. The Curiosity rover has amazing capabilities in organics detection and isotopes. And there's been a whole set of instruments developed over the last 10 to 15 years since Curiosity instruments were picked. And so we have the types of instruments that over the last 10 to 15 years since Curiosity instruments were picked. And so we have the types of instruments that we need now. The trick is getting them on platforms that can get to the surface and getting them down in enough numbers that we can explore many places. I'm optimistic about this. Some of your listeners might be familiar with what's going on at the

moon with the commercial lunar payload services and what the steps that NASA is taking to get more landers to the moon. I think we can extend this to Mars. That'd be great. And that may take us in a moment or two to some work that you're hoping to do at the moon. But I got one more Mars related question for you. And it may be more a moral consideration than a scientific one, and that's planetary protection. We know that JPL is working very hard to make sure that the 2020 rover will not bring too much, more than it absolutely has to, from Earth to Mars that shouldn't be along for the ride, but you can't sterilize things perfectly. Is exploration worth the risk that we could contaminate or damage or even wipe out life on Mars that has managed to hang on for billions of years?

I think this is a serious question. And it has ethical and moral considerations to the value of life beyond Earth, which certainly has a value, I think, intrinsic to itself and not just that we want to find it. Life is precious, I think, wherever you find it in the universe. And so we definitely have to do this exploration carefully on Mars and with concern and caution that said, we need to explore. And so I think there's always a balance to be struck between pushing the frontiers of exploration and then preservation and care in how we do it. There's been a lot of great steps, though, on this over the last, actually just over the last year or two. There's

a new planetary protection officer at NASA, Lisa Pratt, who's a card-carrying geobiologist who came from the University of Indiana. She used to study life underground on Earth and in extreme environments on Earth, and now she's in charge of NASA's planetary protection. But, you know, she herself is at heart an explorer who wants to, you know, find life out there. And so she is, I think, the perfect person to strike this balance. And then recently, NASA in her office commissioned a report to review the planetary protection procedures. And that was led by Alan Stern. And that group has come out with their draft findings. And I think it strikes a nice balance between exploration and the care and the caution not to harm life. We'll have to see if we can get Lisa on the show as we've had.

That would be a great interview. I hope that NASA would, that that would be amenable to that. Yeah, that'd be great. Well, they've let us talk to some of the past planetary protection officers. So we'll hopefully we'll be able to keep that up. She'd be a wonderful person to talk with. Let's go to the moon where planetary protection is not the concern. Less of an issue on the moon. You have a mission which is now a finalist and could actually go into orbit around the moon. Tell us about Lunar Trailblazer. Yeah, this has been one of the most exciting developments in my professional career over the last year. Because in addition to Mars exploration, I've gotten very excited by the potential of small satellites and commercial lunar payloads as well. So small satellites, smaller missions in terms of what they can do. So NASA started this new class of

ride-along missions that basically hitch a ride with a rocket headed out into space. And Lunar Trailblazer was our team's submission to this. So I'm taking my paradigm of following the water on Mars to the moon. And so our team with Lunar Trailblazer follows the lunar water. And we're designed to produce the best map yet of the water ice that's in the permanently shadowed craters in the poles on Mars. Lunar Trailblazer would figure out which of these craters are full and which are empty of water. And we will also have an imaging spectrometer and a multispectral thermal camera to understand if water on the sunlit side of the moon, which was one of the most exciting

discoveries of the 2000s, we want to understand more about this water on the sunlit side of the moon. What is it exactly? Is it H2O or is it some sort of solar wind hydrogen implanted in the surface? Does it change with time? These are some of the things we want to answer with the Lunar Trailblazer. More exciting stuff, Bethany. And I know another exciting thing about your potential spacecraft and the other finalists in this competition is that they're relatively small, which is a trend that we've talked about on the show. And I guess that also means that's going to be easier, cheaper, faster to mount these missions? That's right.

So this is a new class of planetary science mission. The acronym, because everything in NASA has to have an acronym. The acronym is SIMPLEX, which is, I believe, Small Innovative Missions for Planetary Exploration, or SIMPLEX. The SIMPLEX class of missions is an order of magnitude, so a factor of 10 lower cost than the next class of mission, which your listeners may have heard about, the Discovery class mission, which has a $500 million cost cap. These SIMPLEX missions are cost capped at $55 million. How do you do a space mission at $55 million?

Well, you can't buy a rocket and still have a space mission for that amount of money. So the way that Simplex works is it takes advantage of the fact that a lot of rockets launch with excess capacity. And so the planetary science missions hitch a ride on these rockets, their ride along secondary payloads. So your listeners are probably familiar with the Planetary Society's light sail, which got based in the same way as a ride along. So what's happening is that NASA and the associate administrator, Thomas Zurbuchen, see the potential of this to really kind of blow open, democratize and revolutionize the way that we do planetary science, at least in the inner solar system, where there are certain targets like the moon, asteroids, with a little bit of propulsion system help Venus, that can be accessed by these smaller craft. And, you know, with the type and quality and miniaturization of instruments, there are actually a lot of key questions that you can

make a focused set of measurements with a big impact. So they're lower cost, they're higher risk, but NASA wants to do more of them and get more science out there and get more people doing science. that we're not in competition. We're competing against ourselves because NASA managed to find partnership funding between the Planetary Science Division and Heliophysics Planetary Defense and the LDEP Lunar Program to kind of work together to fund all three if we successfully pass our technical reviews, which all happened in the fall of this coming year. So there's three teams working hard to get to space. Wow, that is very exciting news. Thank you for sharing that with us. I was not aware of that. Definitely follow up on it with NASA, because we all have these memos, but there hasn't been a formalization of the announcement.

I will tip off my colleagues at the Society as well. And Bethany, you can count on another conversation, assuming that your review goes well at the end of the year that we're about to start, 2020. And I sure look forward to seeing this spacecraft, Lunar Trailblazer, looking for H2O up there on the moon. My pleasure. And I'm happy to talk about it anytime because water on the moon is another one of these exciting topics. So happy to talk about it and what we can and we plan to do going forward. Exciting really is the word, isn't it? I mean, this is an exciting time to be in your business. It's a very exciting time. I think there's a number of things happening in addition to exciting science. There's just exciting change about access to space that make this a really exciting, invigorating time to be a planetary scientist. Yeah, very happy to have the opportunity to talk to folks like you, Bethany. Thank you for taking the time today to join us on Planetary Radio. My pleasure. That's Bethany Ellman. She is a professor in the Division of Geological and Planetary Sciences at Caltech, the California Institute of Technology, and a research scientist at the Jet Propulsion Laboratory, which is

operated on behalf of NASA by Caltech. And as you've heard, she's a part of many missions underway and still to come out there about our solar system. Another, by the way, she is the author of Dr. E's Superstellar Solar System, Massive Mountains, Supersized Storms, and Alien Atmospheres. It's published by National Geographic's children's books. It's available from all the usual sources. My copy is in the bookcase behind me here in my home studio. And it's a lot of fun, Bethany. How does it feel to be a caped superhero? Oh, this book was so much fun to write. It's really great to talk about space exploration to eight to 12 year olds. And yeah, I got to be a comic book superhero with the sidekick rover. Well, you made a reference to the Wayback Machine. And so that's another superhero. I'm very happy

to be Sherman to your Ms. Peabody, if you don't mind. Sounds like a plan. Thanks again, Bethany. My pleasure, Matt. Thank you. Time for What's Up on Planetary Radio, the very last one on the very last episode of Planetary Radio for 2019. And I am happy to have spent all of these all year long with the chief scientist of

the Planetary Society, Bruce Betts. Another great year hanging with Matt. Yeah. And we'll talk more about highlights and what you might be looking forward to next week when we also talk to the other all-stars from the Planetary Society. We need to talk about what's now, what's happening. What's happening is Venus is looking all birdy in the western sky in the early evening, super bright. And on the 28th, the evening, it's going to be a lovely, lovely sight. We've got the crescent moon hanging out very close to Venus the evening of the 28th. In the pre-dawn east, we've got Mars looking fairly bright and reddish. And to its upper right is the bluish star Spica.

We've got a meteor shower coming up. Always fun to say, quantrantids, an above-average meteor shower. Peaks the night of January 3rd and 4th. From a dark site, you may see as many as 40 meteors per hour. Best viewing will occur after the moon sets, which will be around midnight on the peak night. We move on to this week in space history. It was, of course, 1642 this week that Isaac Newton was born. And then a little bit later in 2003, Mars Express from the European Space Agency successfully went into orbit around Mars, started taking data, and they're still doing it 16 years later.

around Mars started taking data and they're still doing it 16 years later. Yeah. Part of that flotilla up there that we alluded to in my conversation with Bethany. Flotilla. We move on to random space fact. One night only. Mars has about twice the mass of Mercury. Okay. That's good. Since we got Mercury in this week's show as well, and it also has been the topic covered with Bethany. Boy, that really tells you how small Mercury is, since Mars is only, what, a third of the size of Earth? Well, we're mixing dimensions and mass, but it's about half the diameter of Earth, but that means like one-eighth the volume. Just spitballing here.

But yeah, Mercury, it's a wee bit of a pup. We move on to the trivia contest as we celebrate the Planetary Society's 40th anniversary year. I asked you how old was TPS when it was exactly 40 Earth years in Mercurian years. How'd we do, Matt? I'm going to let Dave Fairchild, our poet laureate in Shawnee, Kansas, answer for us. And you can confirm, as always, the Planetary Society is nigh on 40 years, and yet that's not as ancient as it actually appears. If it were moved to Mercury, a fairly awesome trick, the candles on the birthday cake would be 166.

the candles on the birthday cake would be 166. Indeed, happy 166th. I can't even say it, but happy that anniversary, Matt. Hey, when you're that old, you can be excused if I mumble your words now and then a little bit. Here's our actual winner, and this is a nice one. Cole Roberts in Carbondale, Illinois, who said, yeah, 166 of those mercurial years. And he added, I am in Mr. Midden's sixth grade classroom. I know that's Christopher Midden, who, yeah, teaches science there in Carbondale, because we met when I was back there for the big eclipse a couple of years ago. Also is a regular listener to the show.

So, hey, Chris, thanks for getting your kids, forcing them to listen to Planetary Radio, obviously. I'm sure it's voluntary. You know what he's getting? No, I don't. You're going to be thrilled. It's a copy of VR Space Explorers, Titans Black Bat, by a certain Bruce Betts,

and a stylish planetary radio t-shirt. So even better. I mean, we've got a young person who's won and he's winning a young person's book. So yeah. Enjoy the book. And I'd be happy to sign it for him or not.

You know, why not? Why not? I think you should do it. Yeah. Okay. You use your own name. Oh,

I can also sign a Matt Kaplan. I've done it before. Oh, on those checks. I know what you mean. I got a bunch of other great stuff here from Darren Ritchie in the state of Washington. He looked at that 166 and said, happy sex desusquatenial. Same to you. Honorable mention to Nathan Hunter in Vancouver, Washington.

He gave us the answer. I'm not going to read it because he did it out to about 250 decibel places. Yeah, I look forward to seeing that. 250? Yeah, about that. Geez. Yeah, I stopped counting. That's my best estimate. Sid Leach, Scottsdale, Arizona. But how many mercurian days would that be? And he says,

because the day on Mercury, because it rotates so slowly, combined with its orbital speed, the planetary society that is 40 Earth years old would only be 83 mercurial days old that is correct it's a weird place yeah very strange place let's go further out this is from nick in new jersey if we were on k2-137b one of those worlds discovered by kepler we would be the society would be, 81,169 years old. Wow. Its day, sorry, its year is not much longer than the original 1959 Ben-Hur movie. All right, now wait a second.

I've seen Ben-Hur with commercials. It was a terrible, terrible mistake. That's got to be longer. Well, he's probably talking about the theatrical release. Yeah, skip the commercials. Okay. Well, I'm sure that would have been much better. That would have been a better idea. Mel Powell from California, Sherman Oaks, who gets mentioned far too often, but I have to bring up this one. He was looking up the official list of anniversary gifts, you know, like silver is 25th, gold 50th. It turns out there isn't one for the 166th. So he says, it's mercury. It's just a vial of mercury handled with care.

Nice. And finally, that other poem from Gene Lewin at Fairchild Air Force Base in Washington. Some time ago, a group emerged with astronomical intentions and lasting now for 40 years based on our orbital dimensions. If we lived on Mercury, we'd appear to be much older. But during daytime, it's for sure, we'd wish that it was colder. Okay. Bonus, bonus stuff today from our wonderful listeners thank you everybody

thank you we're ready to go on here's your question for next time what planet has the smallest angle between its orbital plane and the orbital plane of earth which is also known as the ecliptic and before you try to get technical on me, not including Earth. All right, go to planetary.org slash radio contest. Yep, and you've got until New Year's Day, January 1st, Wednesday, January 1st at 8 a.m. Pacific time to get us this answer. Come up with a book next week,

but how about a Planetary Radio sticker and a Planetary Radio t-shirt? Both beautiful, of course. You can see them at chopshopstore.com in the Planetary Society store with all of our other merch. We're done. All right, everybody.

Go out there, look up in the night sky and think about light dimmers. Thank you and good night. Is this something to do with absolute versus apparent magnitude? Oh, very much so. Consider that. That's Bruce Betts. He's the chief scientist of the Planetary Society. And he joins us every week here for What's Up and hopefully every week in 2020 as well. Planetary Radio is produced by the Planetary Society in Pasadena, California,

and is made possible by its members who follow the real-life Martian Chronicles. You can join them at planetary.org slash membership. Mark Hilverde is our associate producer. Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. I'm Matt Kaplan at Astra.