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Planetary RadioDecember 25, 2019

What’s Next for Mars Exploration?

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Bethany Ehlmann Head Shot
Bethany Ehlmann

Board of Directors of The Planetary Society; Professor of Planetary Science, California Institute of Technology; Jet Propulsion Laboratory Research Scientist; Associate Director, Keck Institute for Space Studies at Caltech

Bruce Betts Head Shot 2015
Bruce Betts

Chief Scientist / LightSail Program Manager, The Planetary Society

Mat Kaplan
Mat Kaplan

Planetary Radio Host and Producer, The Planetary Society

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.

NASA Mars 2020 rover (artist's concept)

NASA / JPL-Caltech

NASA Mars 2020 rover (artist's concept)
This artist's rendition depicts NASA's Mars 2020 rover studying a martian rock outrcrop.

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Mat Kaplan: [00:00:00] The future of Mars exploration with Bethany Ehlmann this week on Planetary Radio. Welcome. I'm Mat Kaplan at 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 Ehlmann about these mysteries and the path that is taking us towards solving them.

Our second present is another visit with Planetary Society chief scientist Bruce Bets, 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 the sampling. By now you've [00:01:00] probably heard that Boeing 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. They astronauts who may fly in a star liner before long believe they might've 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 Crotoa, 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 when for a drive last week. It all happened in [00:02:00] the big clean room at JPL, which is where Emily Rockwell 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 Springs, 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 including links to learn more about every story.

Bethany Ehlmann 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 [00:03:00] 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 and the coming years and how we hope to make those discoveries. Bethany, I am a very happy to welcome you to Planetary 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.

Bethany Ehlmann: Delighted to be here, Mat.

Mat Kaplan: I know you've taken a look at this article, great article in the current issue currently as we speak, the December solstice issue of the Planetary Report by your colleague Javier Gomez, Elvira titled What Comes Next on Mars. And I'm, 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 [00:04:00] at JPL reporting for my college radio station when Viking One soft landed on the red planet. Are you as awe struck today as I have always been by what the Viking mission at least attempted to do more than 43 years ago?

Bethany Ehlmann: 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, 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 given how long that was ago and at what 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.

Mat Kaplan: What a courageous, valiant attempt. And I still Marvel at [00:05:00] the little laboratories, robotic laboratories that they packed into that spacecraft all those years ago.

Bethany Ehlmann: That's right. They had some very ambitious experiments including x-ray spectroscopy, it's a mass spectroscopy and then these effectively wet chemistry experiments did autonomously.

Mat Kaplan: 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.

Bethany Ehlmann: Happy to. I could keep talking but not 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 in our view of the red planet has forever changed and what we know is the descendant, exquisite level of detail.

That said, we don't know everything and their [00:06:00] big question about ancient climate change, modern climate change and whether or not there's life on Mars, that question is still out there.

Mat Kaplan: 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?

Bethany Ehlmann: I agree. Finding like 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 [00:07:00] magically and 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 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?

Mat Kaplan: Aren't we closing in on that? I mean we've had conversations on this show with, 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 to for that matter.

Bethany Ehlmann: Yeah, I think we're beginning to understand it. And I think there, there are still some important gaps. Let's see. Here are two gaps. Things that [00:08:00] 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 number right off the top of my head, but it's something closer to 20.

Mat Kaplan: We're closing in though.

Bethany Ehlmann: Yeah. Well, but when 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 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 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 [00:09:00] 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, 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 rates. So something else had to happen too.

So what we're getting there, we're like that old adage about sort of feeling different parts of the elephant. The climate model guys 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.

Mat Kaplan: Are some of these missions that are going to be heading toward the red planet in the next two years? Are they going to help us to answer these that you've just posed?

Bethany Ehlmann: Yeah, absolutely. Both of the missions are really important [00:10:00] because they're going to the ancient parts of Mars and they're, they're going ultimately after the life question and also after the climate change is preserved in the geological record. So Mars 2020 we'll 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 of Mars. And there it's going to drill about two meters down, pull up materials and look for signs of [00:11:00] organics and other perhaps hints of life.

Mat Kaplan: This is one of the things that Javier Gomez Elvira 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, on the inside lander. But to be able to pull up samples is this particularly exciting to pull them up from that far down?

Bethany Ehlmann: 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 hit by by [00:12:00] radiation coming through Mars' thin atmosphere that the organics would still be largely untouched. The may be affected a little bit, but largely untouched. So that's why the ex Omar's team has made the decision to go deeper.

Mat Kaplan: This leads me to a sidebar in that a 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 the leadership of a Emily Rockwell, but anybody can find it online at In this sidebar, it goes through a number 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?

Bethany Ehlmann: So this is something that we've thought a great deal about. And I'll say this is [00:13:00] when 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 what chemistry on Mars. We kind of now understand that life has a lot of varied forms and you have to piece together the clues from different directions.

So there are basically six signs of life on Mars. If you want it to be really sure that you had life on Mars, you 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 [inaudible 00:13:40] rock.

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, [00:14:00] 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 [inaudible 00:14:20] of chemical fingerprints. These can be minerals, specific chemical element ratios or isotopes because the processes that are used by life often, especially from 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 are isotopes life tends to prefer the lighter, more abundant isotopes. So, you can get these up kind [00:15:00] of signatures or fingerprints in the chemicals, the minerals in the isotopes.

Mat Kaplan: 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?

Bethany Ehlmann: It's related. Carbon 14 dating for example, uses the carbon in organic material. In this case though of the carbon 14 is 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.

Mat Kaplan: 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?

Bethany Ehlmann: Well, and then the next ones are basically fossils. Either [00:16:00] 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 fossil past of a bone sticking out of a rock. And so these morphologies or structures that suggested in order can be characteristic of life.

Of course 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 a lot. I'm 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.

Mat Kaplan: Yeah, 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 [00:17:00] looked like a trilobite fossil?

Bethany Ehlmann: Yeah, and I have to say reading the internet about every two or three weeks or so, something pops up. From a rock, interpret it 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.

Mat Kaplan: 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.

Bethany Ehlmann: It would be more than a year.

Mat Kaplan: More of Bethany Ehlmann is just ahead. I hope you'll stay with us.

Automated: 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. [00:18:00] A certain very much beloved daughter will match our gifts up to a $100,000. Please make your gift today and see your impact doubled. Go to Thank you indeed.

Mat Kaplan: When the news came from NASA about that famous Martian meteorite, that there were these funny little structures in there that sure look 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."

Bethany Ehlmann: 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 yet as 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 [00:19:00] ID. Now Allan 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, and Allen Hill's 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 varying compounds and also the mineral magnetite and have I think explained the Allan Hills 84001 data and in light of that particular hypothesis. And if 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, having read some of the manuscripts pro and con. I also don't think that they've disproven [00:20:00] it is life. It's one of these things about burden of proof. Where's the proof deal? We 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.

Mat Kaplan: Yeah. Well at least it's one piece of evidence. But yeah, one data point

Bethany Ehlmann: It is. An 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 at least points to the signs and conditions that could have supported it.

Mat Kaplan: 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 [00:21:00] 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?

Bethany Ehlmann: 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 a 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 light Gale crater where the Rover is now, Jezero is what geologists would call us 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.

Mat Kaplan: It's gorgeous. [00:22:00] It's, amazing.

Bethany Ehlmann: 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. I, for one, I have to say I've 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 in 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 strata, like pages in a book.

And we can step [00:23:00] 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 and get onto the plateaus and go study an even more ancient period of Mars history and collect samples while doing it.

Mat Kaplan: Let's hope that the 2020 Rover will live long and prosper like Opportunity and make that trek across Mars. That would be fantastic.

Bethany Ehlmann: Yeah. Well like Spirit, Opportunity and Curiosity, they have all so far outlived their warranties. We can't count on it, but so far so good. We're set.

Mat Kaplan: Fingers crossed. As you talk about these things and how we pick sites on Mars, it reminds me that of course our rovers, our landers have visited far less than 1% of the planet. That's 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?

Bethany Ehlmann: That's right, yeah. I'm on the CRISM imaging spectrometer team.

Mat Kaplan: And that's [00:24:00] how we've been able to learn a lot about most of the, or a lot of the planet, right? From a distance.

Bethany Ehlmann: 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 you what Mars is made of at that point. So you pair these imaging spectrometer data with the high resolution images from like the CTX camera, high rise camera, and you're able to make these amazing 3D reconstructions and like read the rock layers over time detecting things like clay minerals, carbonates, silica, chlorides, that all points, all different types of aqueous environments, water rich environments all over the planet.

Mat Kaplan: 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 [00:25:00] 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.

Bethany Ehlmann: Yeah. Six meters per pixel and 30 centimeters per pixel respectively. It's pretty darn good.

Mat Kaplan: 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 a 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?

Bethany Ehlmann: 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 [00:26:00] 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 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 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.

Mat Kaplan: I would love to hear more about your thoughts in that area.

Bethany Ehlmann: I'm happy to talk about it that because the question of, I think whether Mars has water today or has life today is still not answered. [00:27:00] 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 of roved around will five and with XMR 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've missed. Did you pick the right sites? How do you know?

Mat Kaplan: Yeah, we're back to the blind men and the elephant like you were talking about.

Bethany Ehlmann: 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 [00:28:00] past life and about climate change require the types of measurements of organics and isotopes in 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.

Mat Kaplan: 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?

Bethany Ehlmann: 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 we need now. The trick is getting them on platforms that can get to the surface and getting them down and enough numbers that we can explore many places. I'm, I'm optimistic about this. Some of [00:29:00] 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.

Mat Kaplan: 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 of 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, or even wipe out life on Mars that is managed to hang on for billions of years.

Bethany Ehlmann: I think this is a serious question and it has ethical and moral considerations to the value of [00:30:00] 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 the preservation and care in how we do it. There's been a lot of 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 geobiologists 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 and Explorer who wants to find life out there. And so she is I think the perfect [00:31:00] person to strike this balance. And then recently NASA and her office commissioned a report to review the planetary protection procedures 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.

Mat Kaplan: We'll have to see if we can get Lisa on the show as we've had [crosstalk 00:31:21].

Bethany Ehlmann: That would be great. It would a great interview. I hope that the NASA that that would be amenable to that. Yeah, that'd be great.

Mat Kaplan: Well, they've let us talk to some of the past Planetary Protection Officers, so hopefully we'll be able to keep that up.

Bethany Ehlmann: She'd be a wonderful person to talk with.

Mat Kaplan: Let's go to the moon where planetary protection is not the concern.

Bethany Ehlmann: [crosstalk 00:31:40] on the moon.

Mat Kaplan: You have a mission, which is now a finalist and could actually go into orbit around the moon. Tell us about Lunar Trailblazer.

Bethany Ehlmann: 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 [00:32:00] 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 multi-spectral 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 [00:33:00] change with time? These are some of the things we want to answer with the Lunar Trailblazer.

Mat Kaplan: 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?

Bethany Ehlmann: That's right. So this is a new class of planetary science mission, the acronym because everything, NASA has to have an acronym, the acronym, SIMPLEX, which is I believe Small Innovative Missions for Planetary Exploration or SIMPLEX. This SIMPLEX class of missions is an order of magnitude. So a factor of 10 lower costs 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 cap at 55 million. How do you [00:34:00] 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 launched with excess capacity. And so the planetary science missions hitch a ride on these rockets. They're ride along secondary payloads. So your listeners are probably familiar with the Planetary Society is LightSail.

Mat Kaplan: You bet.

Bethany Ehlmann: Which got placed 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 with the type and quality and, and miniaturization of instruments, there are actually a lot of key questions that you can make a focus set of measurements with a big [00:35:00] 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.

One other final thing, and, and, and I don't think that NASA's made a public announcement, but back in September, the three of us finalists in the competition received a memo that said, actually, that we're not in competition. We're competing against ourselves because NASA Managed to find a 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 happen in the fall of this coming year. So there's three teams working hard to get to space.

Mat Kaplan: Wow. That is very exciting news. Thank you for sharing that with us. I was not aware of that.

Bethany Ehlmann: Definitely follow up on it with NASA because we all have these memos but there hasn't been a formalization of the announcement.

Mat Kaplan: [00:36:00] 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.

Bethany Ehlmann: 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.

Mat Kaplan: Exciting really is the word, isn't it? I mean, this is an exciting time to be in your business.

Bethany Ehlmann: 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, about access to space that make this a really exciting, invigorating time to be a planetary scientist.

Mat Kaplan: 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.

Bethany Ehlmann: My pleasure.

Mat Kaplan: That's Bethany Ehlmann. She is a [00:37:00] 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 a still to come out there about our solar system.

Another by the way, she is the author of Dr. E's, Super Stellar Solar System, Massive Mountain Supersize Storms and Alien Atmospheres. It's published by National Geographic's children's books. It's available from all of 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?

Bethany Ehlmann: 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.

Mat Kaplan: Well you, you made a reference to the way back machine and so that's another superhero. I am very [00:38:00] happy to be Sherman to your Ms. Peabody, if you don't mind.

Bethany Ehlmann: Sounds like a plan.

Mat Kaplan: Thanks again, Bethany.

Bethany Ehlmann: My pleasure Mat. Thank you.

Mat Kaplan: 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 a happy to have spent all of these all year long with the chief scientist of the Planetary Society, Bruce Betts.

Bruce Betts: Another great year hanging with Matt.

Mat Kaplan: 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.

Bruce Betts: What's happening is Venus is looking all birdie 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 [00:39:00] predawn East, we've got Mars looking fairly bright and reddish and to its upper right, is the blue star speaker.

Got a meteor shower coming up that always fun to say. Quadrantids and 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 go up to 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.

Mat Kaplan: Yeah. Part of that flotilla up there that we alluded to in my conversation with Bethany.

Bruce Betts: Flotilla. We move on to-

Automated: Random Space Facts. One night only.

Bruce Betts: Mars has [00:40:00] about twice the mass of Mercury.

Mat Kaplan: Okay. That's good. Since we got Mercury in this week's show as well, and it also has been the topic I covered with Bethany. Boy that really tells you how small Mercury is since Mars is only what a third of the size of earth.

Bruce Betts: Well, we're mixing dimensions and mass, but it's [crosstalk 00:40:19].

Mat Kaplan: True.

Bruce Betts: It's about half the diameter of earth. But that means like one eighth the volume. Just spit balling here. But yeah. Mercury, it's a wee bit of a pup. We move on to the trivia contest as we celebrate the planetary side'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 a Mat?

Mat Kaplan: 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, [00:41:00] the candles on the birthday cake would be 166.

Bruce Betts: Indeed. Happy 166th. I can't even say it, but happy that anniversary man.

Mat Kaplan: Hey, when you're that old you can be excused if you 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. Mitten's sixth grade classroom. I know that's Christopher Mitten 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 a Planetary Radio obviously, but-

Bruce Betts: I'm sure it's voluntary.

Mat Kaplan: You know when he's getting?

Bruce Betts: No, I don't.

Mat Kaplan: You're going to be thrilled. It's a copy of VR Space Explorers [00:42:00] Titan's Black Cat, 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.

Bruce Betts: Enjoy the book and I'd be happy to sign it or not.

Mat Kaplan: Why not? I think you should do it. Yeah.

Bruce Betts: Okay.

Mat Kaplan: Use your own name.

Bruce Betts: Oh, I can also sign it Mat Kaplan. I've done it before.

Mat Kaplan: Oh, on those checks. I know what you mean. I got a bunch of other great stuff here from Darren Richie in the state of Washington. He looked at that 166 and said, "Happy, um, six deci sesquicentennial."

Bruce Betts: Same to you.

Mat Kaplan: Honorable mention to Nathan Hunter in Vancouver, Washington. He gave us the answer, I'm not going to read it, but because he did it out to about 250 decimal places.

Bruce Betts: Yeah, I [00:43:00] look forward to seeing that. 250?

Mat Kaplan: Yeah, something like that. I stopped counting. That's my best estimate. Sid Leach, Scottsdale, Arizona, "But how many Mercurial days would that be?" And he says, "Because the day on Mercury, because it rotates so slowly at combined with its orbital speed. The Planetary Society that is 40 earth years old would only be 83 mercurial days old."

Bruce Betts: That is correct. It's a weird place.

Mat Kaplan: Yeah. Very strange place. Let's go further out. This is from Nick Jury in New Jersey. "If we were on K2137B one of those worlds discovered by Kepler, we would be, the society would be 81,169 years old. It's year is not much longer than the original 1959 Ben-Hur movie."

Bruce Betts: All right. Now wait a [00:44:00] second. I've seen Ben-Hur with commercials. It was a terrible, terrible mistake that's gotta be longer.

Mat Kaplan: Well, he's probably talking about the theatrical release. Yeah. Skip the commercial.

Bruce Betts: Okay, well sure, hat would have been much better. I would've been a better idea.

Mat Kaplan: 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 like silver is 25th or 50th. It turns out there isn't one for the 166th. So he [crosstalk 00:44:32] it's Mercury. It's just a vile of mercury handle with care.

Bruce Betts: Guys.

Mat Kaplan: And finally that other poem from Jean Lewin at Fairchild Air Force Base in Washington. "Sometime 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 wished that it was [00:45:00] colder." Okay. Bonus stuff today from our, our wonderful listeners. Thank you everybody.

Bruce Betts: Thank you.

Mat Kaplan: We're ready to go on.

Bruce Betts: 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

Mat Kaplan: Yep. And you've got until New Year's Day, Wednesday, January 1st at 8:00 AM 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 in the Planetary Society store with all of our other merch. [00:46:00] We're done.

Bruce Betts: All right. Everybody go out there and look up in the night sky and think about light dimmers. Thank you. And good night.

Mat Kaplan: Is this something to do with, with absolute versus apparent magnitude?

Bruce Betts: Oh, very much so. Consider them.

Mat Kaplan: That's Bruce Betts. He's the chief scientist of the Planetary Society. Any he joins us every week here for What's Up and hopefully every week in 2020 as well.

Automated: Planetary Radio is produced by the Planetary Society in Pasadena, California, and it's made possible by its members who follow the real life, Martian Chronicles. You can join them at Mark Hilverda is our Associate Producer, Josh Doyle, composed our theme, which is arranged and performed by Peter Schlosser. I'm at Mat Kaplan. Ad astra.

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