Planetary Radio: Space Exploration, Astronomy and Science - We Know Where the 2020 Rover Will Look for Martian Life

Episode Date: November 21, 2018

NASA announced on November 19th that the multi-billion dollar 2020 Mars rover will land in Jezero crater, where it will begin the search for the signature of past life. The selection process took five years, and Briony Horgan of Purdue University was part of it all. She joins us to talk about this exciting and enticing target on the Red Planet. Planetary Society Senior Editor Emily Lakdawalla prepares us for the much more imminent Mars landing of InSight. Orion in the northern hemisphere’s night sky can only mean winter is coming. Just ahead of it is a new What’s Up segment from Bruce and Mat. Learn more at:  http://www.planetary.org/multimedia/planetary-radio/show/2018/1121-2018-briony-horgan-2020-rover-jezero.htmlLearn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

A rover targets life on Mars, 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. We now know where the 2020 rover will land on the Red Planet. NASA made the announcement on Monday, November 19th, exactly one week before another spacecraft descends to Mars. Planetary scientist Brian E. Horgan will tell us about the promise of Jezero Crater and how it was chosen. First, though, we'll check in with senior editor Emily Lakdawalla for a look at what to expect when the inside lander begins its seven minutes of terror on November 26th.

A dog puts the first paw prints on Mars? That's a hint about one of the prizes Bruce and I have for the winner of a new space trivia contest coming in this week's What's Up segment. Emily, it looks like we are just days away from another white knuckle landing on the red planet. We are. It's going to be exciting as it always is as we approach, in this case, a six minutes and 45 seconds of terror as InSight gets ready to land on the surface of Mars on November 26th. I have in front of me your blog entry at planetary.org for November 12th. And you have all of this in detail and you include this neat little graphic that you created that traces what we can expect. It's always a challenge to put together

all the bits and pieces of information that come out from different sources. And so I love to just assemble these infographics that have every last detail on it. And then I share them out into the world for the benefit of everybody else who has the same problem I did. Our friend, Rob Manning, the man who knows more about putting things down softly on the surface of bars than I think any other human, has this great video, which you have a link to from the blog post. But even the audio is so good. I mean, the video is great as well, because it's like a combination of a transparent wipeoff, transparent wipe-off board and CGI, which is really fun. But the audio is so great that I think we'll just use it right now. Although we've done it before, landing on Mars is hard, and this mission is no different.

The process to get from the top of the atmosphere of Mars to the surface we call Entry, Descent and Landing or EDL. It takes thousands of steps to go from the top of the atmosphere to the surface and each one of them has to work perfectly to be a successful mission. The process starts well above the top of the atmosphere of Mars. The crew stage faces the sun. It also has its radio antenna, which faces Earth. But now we don't need the cruise stage. Its job is done. The next step, just seven minutes before arriving to the top of the Mars atmosphere,

is to separate the cruise stage. Before you hit the top of the atmosphere, though, the space capsule has to orient itself so that the heat shield is precisely facing the atmosphere. Now the fun begins. The vehicle is moving at nearly 13,000 miles an hour, but it's hitting the top of the atmosphere at a very shallow angle, 12 degrees. Any steeper, the vehicle will hit the thicker part of the atmosphere and will melt and burn up. Any shallower, the vehicle will bounce off the atmosphere of Mars. At the very top of the atmosphere, it's about 70 miles above the surface of Mars and the air is starting to get thicker and thicker and

thicker. As it does that, the temperature of that heat shield gets well over a thousand degrees centigrade, enough to melt steel. Over the next two minutes, the vehicle decelerates at a back-breaking 12 Earth Gs, from 13,000 miles an hour to about 1,000 miles an hour. At about 10 miles above the surface of Mars, a supersonic parachute is launched out of the back of the vehicle. Fifteen seconds after the parachute inflates, it's time to get rid of the heat shield. Six pyrotechnic devices fire simultaneously, allowing the heat shield to fall

and tumble away from the vehicle, exposing the lander to the surface of Mars. 10 seconds after the heat shield is dropped, three pyrotechnically deployed legs are released and locked for landing. the technically deployed legs are released and locked for landing. About a minute later, the landing radar is turned on, sending pulses toward the surface of Mars as the vehicle starts to try to measure how high it is above the surface and how fast it's going. At about a mile above the surface of Mars, the lander falls away from the back shell and lights its entrance.

And very quickly, the vehicle must rotate out of the way so that the parachute and the back shell doesn't come down to hit it. The last thing that has to happen is that on the moment of contact, the engines have to shut down immediately. If they don't, the vehicle will tip over. So if all the steps of entry, descent, and landing happen perfectly,

and we are safely on the surface of Mars, we'll be ready to do some exciting new science. So that's Rob Manning of the Jet Propulsion Lab on what we can expect. If all this goes according to plan, Emily, when are we going to get back those images? I want my pictures. Well, we actually don't know the answer to that question. As usual, the spacecraft will take some photos with its cameras right after landing. The main one that'll show us footpads on the ground, that camera will still have a dust cover on right after landing. We can hope that we'll get those pictures back right after touchdown, which does frequently happen, but we can't be sure that there will be enough space,

enough bandwidth for the spacecraft to actually transmit it at the time that it lands. And so we might have to wait a couple hours. We might even have to wait several hours, but I really don't expect that. I hope to see images pretty quickly. Now, these are going to have to be relayed back to Earth, right? Yes, that's how it works. InSight has a pretty small radio antenna. It uses that antenna to communicate with orbiters. Or in the case of InSight's landing, it's actually going to be relaying data through two CubeSats that are flying past Mars as an experiment to try to test this kind of

communications for the future. So it's possible that we'll get this data, the telemetry, and the first images through these tiny suitcase-like spacecraft named Marco, which would be really cool if it happens. Very cool and really good for the show that we're going to put on at Caltech as this happens. If you want to learn more, planetary.org slash events has a link to the Eventbrite page. You do need an RSVP, but it is free. And we will be following along the NASA TV coverage there with some great people on stage. As if I didn't know, where will you be, Emily? I'll be at JPL with all the press, you know, holding our breath, hoping that everything went well,

and then being excited and writing everything down as soon as things do go well. You know, I do feel like we take for granted now the fact that Mars landings have seemed to go off without a hitch for a long time. And I have to keep reminding myself that things may not go well, but we'll find out for sure one way or another on November 26th. All right. We'll all be holding our breath along with you and all those other folks at JPL and around the world. Thanks, Emily. Thank you, Matt. That's our senior editor, the Planetary Evangelist, and the editor-in-chief of the Planetary Report, the magazine from the Planetary Society that goes to our members.

But you can read it online for free. We'll check in with her again before long, very possibly to talk about the success, we all hope, of the InSight lander. We're going to call it Jezero, but if you read Emily Lakdawalla's November 20th blog post at planetary.org, you'll learn that our pronunciation of that Martian crater's name is open to debate. And you should read Emily's post for a great guide to the just-announced target for the 2020 rover, enhanced by lots of images and graphics. But I also learned a lot in my conversation with Bryony Horgan. Bryony is an assistant professor in the Department of Earth Atmospheric and Planetary Sciences at Purdue University. But this planetary scientist was also a major player

in the long and winding process that ended on November 19th with the selection of Jezero. She joined me from her office not long after the announcement was made. Bryony, thank you very much for joining us on Planetary Radio on very short notice. And congratulations to you and the rest of this team that has delivered this really momentous decision about where the next rover will be going on Mars. Thank you. Yeah, we're very excited that we have a landing site for Mars 2020. We're absolutely thrilled.

And we're going to talk about that site, but I'm hoping we can spend a couple of minutes up front talking about that process that led to its selection. You are a good person to talk to about this because you and Sanjeev Gupta, I can't say you wrote the book, but you wrote the PowerPoint presentation that I've been poring over and that my colleague Emily Lakdawalla

refers to many times in her brand new blog post about this selection of this site. And we'll link to it, by the way, from the episode page that people can find at planetary.org slash radio. But of course, it wasn't the only site under consideration, was it? No, it wasn't. So we actually had four final sites going into this last round of consideration for Mars 2020. They included Gusev Crater, which was previously visited by the Spirit rover. And the motivation for that site was ancient hydrothermal springs that were investigated by Spirit and could potentially contain microbes entombed by silica. We had two sites that were actually pretty nearby Jezero,

northeast Cerdas and Midway, both of which were these really ancient sites on Mars that were ancient crustal materials that could tell us a lot about the early history of Mars and very early environments in the surface and subsurface. And then finally Jezero, which is sort of in that same area, but it's this ancient crater lake that we think could really be a great place to investigate not just the habitability of ancient Mars, but also look for signs of life in this ancient lake environment. Now, I know some of the scientists who were pulling for one or the other of these sites that was not selected, and yet they all seem to be satisfied, well, the ones I've spoken to, that this is certainly, Jezero is a really promising

place to go. It is, you know, and one of the reasons it's been a popular site throughout this five-year-long landing site selection process, because it just has a lot going for it. We think it's old, and we think it dates from the period in Martian history when the most water was present at the surface, when we see evidence for all of the valley networks and lakes, at least the majority of them forming. And so, you know, going, being able to go to a time in Mars' past when life was, we think probably the most likely to be present is a huge, huge advantage for this site. But it's not just that, that it, you know, was a lake at this time. It also has volcanic deposits. It has minerals that precipitated out of that lake. It has beautiful deltaic features that we can investigate to understanditated out of that lake. It has beautiful deltaic features

that we can investigate to understand the history of those lake processes. And it's smack in the middle of this really ancient crust on Mars that we think is sort of a window into the early evolution of not just Mars, but other planets in the solar system as well. Yeah, whatever else it may prove to be once we get there, this site certainly doesn't look from above like it will be boring. It really is very diverse. And what is this particularly interesting, well, to me anyway, that this area that certainly looks like a river delta? It does. Yeah. So that's one of the really great things about this site is that we have this clear evidence for this well-developed system of river valleys that feeds into this lake. When the rivers hit

the lake, they dropped their sediment out and formed this delta that built out into the lake. And then eventually we actually also see evidence that this lake breached, that it breached the other side of the crater rim to form an outflow channel on the other side. So that tells us not only was there water in this crater, that it was there, it was deep enough and it was there for long enough to actually flow out the other side. And so we think there's a really great case that there was a long-lived, watery environment here for life to live in. We've talked about the 2020 rover and even about the site selection process several times in the past. What were the major factors that were being taken into account as all four of these sites

were being considered? So there were a couple of big things. So we had a few big goals or big objectives we had to evaluate when we were looking at these sites on the science team. And we spent the last two or three years on the science team looking at these sites ourselves, actually going back and looking at the original data, trying to make sure we agreed with all the interpretations that other scientists have put out there, and really trying to do as good of a job as we could internally as well, evaluating these sites. And so we spent a lot of time looking at all four of these sites. So the big things we were trying to understand was first off, you know, does the site contain a geologically compelling story, right? Can we go to this site and understand the geological story? The second one was, is there, can we conduct a good astrobiology mission at this site?

Can we try to understand an ancient habitable environment? And then can we also look for biosignatures? And those are two, you know, they seem similar, but they're sort of different investigations, right? And of course, the third one is, are there opportunities at this site to collect samples for future sample return, which is a very important consequence of the Mars 2020 mission. And it's one that we're holding in the back of our minds at all times. And so when we're looking at these sites, we're trying to understand, okay, how much do we really know about the geology? How much will the rover

be able to add to our understanding of the geology at that site? And then based on that, how well do we think we'll be able to conclusively identify or even search for biosignatures at these sites? So they all kind of interplay together, and the different sites have different strengths and weaknesses in all of those categories. You're a planetary scientist, I believe primarily a geologist. If you will speak from the biology side for a moment, what tells us that this is a good place to look for biosignatures? Probably of past life, but we won't know until we go there. Right, exactly. So really it's the evidence for a long-lived watery environment. So the presence

of the Delta tells us that there was a lake here for long periods of time. What's also really interesting about this site though, is that it's not just the Delta. We also see evidence for minerals that precipitated out of the lake, potentially. We think we see evidence for that from orbit. And basically when that happens, you can actually trap anything that's living in the lake in those minerals. In particular, we see evidence for minerals called carbonates. This is similar to, you know, things like limestones you might find on Earth, which are great at trapping microbial fossils, organic matter, all kinds of stuff like that. So it's the combination of minerals precipitating out of the lake, along with the delta itself, bringing in all kinds of materials, sediments and organics and biosignatures from the

surrounding terrains and depositing them in the lake and then trapping them in the sediments it's laying down. So it's really all about trapping and preserving all those signs of life, everything from organics to minerals to microbial fossils and things like that. That's really that ability to trap those biosignatures that we're looking at in this lake. When this rover, the 2020 rover, as yet to be given an acuter name, rolls up to one of these sites that appears to be a good place to look for biosignatures, what will it have on board that will enable us to look for the remnants of possible life? So the really great thing we have with this rover that we haven't had in the past is the ability to do very high resolution imaging of these rocks. And not just imaging.

scale and do things like look for, okay, where are the organics and map them out with instruments like the Sherlock instrument, which is a spectrometer that can actually make maps of the minerals and organics and other species that are in the rocks at a very, very small scale. We can also make maps of the chemistry of the rocks at very similar scales. And we also actually have remote sensing instruments too that can detect organics and other minerals from standoff distance. And so we have this whole strategy for the mission where we'll come up to a site, say, for example, the site of this ancient delta. We'll do a survey of this site using our remote sensing instruments, and then we'll identify places we want to look at in much more detail

with our microscopic and sort of high-resolution contact instruments. Once we do that, once we kind of know what's going on, then we can decide whether or not we want to take a sample at this site to bring back to Earth eventually to do a much more detailed search for biosignatures in these rocks. That remote sensing that you mentioned, is that this more advanced descendant of ChemCam that's on Curiosity? Yes, that's the SuperCam instrument. And it's called Super because it can do so many things at once. It has the same abilities that ChemCam did, where it basically uses a laser to create a plasma in the rocks. And then can look at the elemental chemistry of the rocks based on the light that's emitted by that plasma. It can also, though, do standoff Raman spectroscopy. So similar to our

microscopic Sherlock instrument, but at a standoff distance, so we can get a sense of what's in the rock before we go look at it up close. And then it also actually can do a different kind of spectroscopy sort of in the long sort of red wavelengths, near and fred wavelengths, which will help us identify the minerals that are in the rocks. And so it can kind of do all this stuff all at once. And so we're pretty excited to apply that once we get on the ground. Pretty cool instrument. Is this rover going to have, it sounds like, it may have just a more powerful microscope than Curiosity has? Yeah, so on Curiosity, the only high-resolution imaging instrument we have is MOLLE, which is the Mars Hand Lens Imager, which is really just a camera, but a very, very good one that can get very high just resolution imagery.

So on Mars 2020, what we're going to have instead is not just that we'll be able to map out all of the minerals and organics and all the things at that same kind of scale, which will help us identify, you know, could those organics be a biosignature or are they just organics that are present all over Mars? All right. Speaking of cameras, up on top, up on the mast is of course going to be Mastcam-Z that we've talked about on this show in the past. And you're a co-investigator for that amazing stereo vision system, I believe going to be the most advanced camera ever to go to the surface of Mars. How will it play a part in searching for this evidence of at least past life? Well, Mastcam-Z is literally the eyes of the rover, and we're really excited to use the eyes to identify where we're going to do our

in-situ and deep sampling of these rocks. So Mastcam-Z is not just a camera, it is actually a pair of cameras that have the ability to zoom in and out and get really beautiful high resolution images of the surface and stereo as well, because we have two cameras, we can make 3D maps of the surface. But the really great thing about Mastcam-Z is that in addition to all of that, in addition to the beautiful images and the stereo imaging we'll be able to do, we can also actually also do mineral mapping with this camera because we have the ability to do spectroscopy with the camera. We use filters to put in front of the camera to take pictures at very specific wavelengths.

And then we can look for absorptions of light at those wavelengths due to different kinds of minerals. This is the kind of work we're already doing with the Mastcam on the Curiosity rover. But we've actually been working really hard to update that technique for Mastcam-Z, and we'll be able to detect more minerals at higher resolution. We're really excited to help use that data to identify where we should be looking for biosignatures. I'm looking at that presentation that you co-created. There are several slides in here that go to that sample collection, which is one of the main jobs of this rover. You actually have graphics on some of these slides that show some of what look like the cores that may be brought up out of the ground and stored away for safekeeping. Right. Yeah.

So, you know, the Mars 2020 rover, the goal of the rover itself when it's doing its in situ mission on ground, is to do astrobiology, right, to look for biosignatures. It's what we've been building up to for decades now with the Mars Exploration Program. But really, to do that well, to look for better, concise evidence of biosignatures, we need to bring those samples back to Earth and look at them using, basically throw everything we can at them, everything but the kitchen sink, right, to try to see if we can see definitive signs of life in these samples. And so that's one of the big goals of Mars 2020, then, is to collect this suite of samples that we can do lab astrobiology with back here on Earth. But of course, in addition to astrobiology, Mars sample return is an incredible opportunity to do really great geology as well. And so we're not just bringing back samples that are good astrobiology. We also want to bring back things like lava flows that could tell us about the volcanic history of Mars, the initial formation of the planet. We want to bring back samples of minerals that could tell us about the history of the atmosphere and why Mars has lost so much of its atmosphere, for example. Things that could tell us about the history of water on the planet. And there's a whole suite of things we would love to bring back.

Unfortunately, we only get to bring back a very small number of samples, probably something like 20 samples. And so one of the jobs of the rover, in addition to looking for biosignatures, is going to be selecting that suite of rocks, you know, sort of pencil-sized core samples that we will hopefully be able to bring back with a future mission. And that's going to be challenging, right? Because this is, okay, we're going to one site, we have this one opportunity to collect rocks that might come back from Earth to Mars. What rocks do you choose, right? What small sampling of the huge diversity of rocks we've seen on Mars already would you bring back to study in labs on Earth? And that's a really challenging question. It's going to be one of

the big questions we'll have to address with the mission. We already have some idea, right? So we've already presented a possible suite of samples we could bring back from Jezero Crater. And they're really exciting. It ranges from everything from these mineral precipitates that we think could have formed in the lake, to the delta sediments, to the volcanic materials that are in the crater, as well as many other types of samples. One of the really compelling reasons that we chose Jezero Crater, that we supported Jezero Crater, is because of this diverse sample suite we could possibly get back. Sounds like you'd like to get your hands on a gram or two of those samples when they make it back here. Oh, I would love to hold a piece of Mars in my hand. That would be great.

I know that you have a lot to weigh in making this choice. Each site had its pros and cons. What are some of the, what's the downside of Jezero? Yeah, so Jezero has a few challenges. One thing on the surface, you know, we actually have really beautiful images of Jezero. It's pretty dust free. We can see all the beautiful textures and colors in the rocks, but that's because it's a pretty windy place. And there's a lot of sand moving around and blasting all that dust away. And so there's a lot of sand ripples and dunes that are on the surface. The engineers think it won't be a problem. There are plenty of risk free paths that we can use to get around to the major places in the crater. One of the concerns about Jezero is that, you know, it doesn't have

some of the things that the other possible landing sites have. You know, for example, at the Gusev crater, the Columbia Hills landing site where Spirit investigated, Spirit identified silica-bearing little fingery rocks associated with an ancient hydrothermal spring that could be actually in and of themselves, based on the Spirit data, potential biosignatures. Youatures. Scientists have observed these silica digitate forms that we've seen at Gusev on Earth and associated with microbial activity and actually trapping microbial sort of remnants in them as well.

And so that was the really strong argument for Gusev is that we know what we're getting into. We know the biosignatures, potential biosignatures are there. So it's a very simple mission to go get them. So at the other sites, we don't have that, right? All we have is orbital data. We don't have the on the ground, you know, ground truth that there are indeed great rocks there for us to sample for biosignatures. But at the same time, Gusev crater was a place we've been before. We've done a lot

of the basic geology. We've learned a lot about Mars from it. What is a little unclear is how much more you could learn about Mars by going back with a better rover. Is it enough to justify several billion dollars, not just from Mars 2020, but from future Mars sample return as well? So thinking more about the other sites that were around Jezero, so Northeast Cerdas and Midway. So these sites were sort of, again, this ancient crustal environment on Mars. The argument for those sites is one that they would tell us a lot geologically about the history of Mars, about how Mars formed, about the really early formation of the crust and hydrothermal processes and all kinds of exciting things like that. But there's also an astrobiological argument for those sites. And that's that these sites might preserve rocks

that were basically hosted subsurface environments, that hosted things like hydrothermal systems or aquifers or other environments that could have supported a very different kind of life from, you know, the kind of life we're looking for in a surface lake, right? So somewhere like Jezero, we're really looking for things like microbial mats or microbes living in the water column that deposit out organics. That's a very different environment and a very different kind of ecosystem from something like a subsurface environment, which we do know exists on Earth. There are enormous, huge amounts of microbes that live underground on Mars, or excuse me, on Earth. And we know they're there. Wishful thinking.

Well, so that's one idea is that people think, you know, we have this incredibly active subsurface environment on Earth. On Mars, the problem with looking for life at the surface is that, you know, the surface of Mars today, and really for the last three plus billion years, has been almost inhospitable. And so why not go to the place where we think microbes could have lived for a much longer period of time, and that's kind of in these protected subsurface environments. And so that's the argument for going to these, the astrobiological argument for going to these more subsurface crustal sites, is that it's a very different type of astrobiological investigation that a lot of people are very strongly behind. But, you know, what's nice about Jezero is that

we're kind of sticking to what we know from Earth. We know that in the Earth geological record going back, you know, hundreds of millions, even billions of years, that these kind of lake environments are really great at preserving organics, at preserving biosignatures. And so we're kind of, Jezero on some level is the safe choice in terms of what we know from Earth. Isn't there an outside chance that this rover might be able to reach one of, at least one of those other sites? Yeah. So that's the option that we're extremely excited about is that because of the incredible advances in mobility and software with Mars 2020, that we think we will be able to rove out of Jezero Crater onto the surrounding plains

to one of these other sites, to the Midway site, which contains these ancient crustal rocks and ancient maybe crustal subsurface environments. We call this the mega mission. It's a really exciting possibility that we could sample both of these environments and maybe get both of those sets of samples back to Earth to look at as well. It would really cover so much ground. It would answer almost every major question we have about Mars that we could answer with sample return. And so if we can do that, that would be a very bold mission, but it's a really, really exciting opportunity. Yeah, something to hope for, but still shame that we can't just send four rovers, right? I know, right?

What about those engineering challenges? I mean, I have read that this is not quite as friendly a place to land if those engineers want to get you down there safely to do science. science? So Jezero, so all the sites have been through a very rigorous entry, descent, and landing analysis in terms of winds and altitude, you know, all these things that affect landing. And from what I understand, the engineers are very confident about all four of the final landing sites, including Jezero. So I don't know, I haven't heard any other details about specific. And I know some of that is more advances in the 2020 rover over Curiosity, right? Because it's going to be able to kind of zero in a little much more accurately, I guess, on its actual landing site. Yeah. So the landing ellipse size, which is area of probability that

will land in, is absolutely getting tiny when it comes to Mars 2020. We're talking about on the order of less than 10 kilometers across, which when you compare that to, you know, the European ExoMars rover, their landing ellipse is like 100 kilometers long. And so just the technology that's gone into being able to do that includes things like terrain relative navigation, where the rover actually senses the ground below it and can try to navigate to avoid big hazards has really, really helped to reduce the size of that ellipse. At Jezero, the ellipse is actually partially on the delta, which is pretty cool considering there's a big delta cliff running through part of the ellipse, but the engineers are confident that the rover can navigate that during landing. It's amazing. We have literally come a long ways on the red planet. You talked

about this five-year process to reach this point. Is this a good example of science working the way it should and scientists working together the way they should? I think so. I think the way that NASA's learned a lot from all the different landing site selection processes leading up to the Mars 2020, what I really like about this process is that it was a great mix of community involvement. The initial 60 or so sites were all proposed by the community. And up through the last landing site workshop, including this last one, there were community presentations. You know, no one was sent away.

Anyone could present anything they wanted on any of these landing sites. We had lots of great discussion, but we also had a lot of involvement from the science team on these landing sites and doing our own independent analysis, you know, and trying to think about, you know, what our rover could really do at each of these sites, which, you know, we have the best perspective

on. And so I really like that kind of even handed mixture of input from the community, but also sort of rigor from the science team trying to keep everybody honest. So I think that ended up working really well. And I'm ultimately really happy with our selection. You've been working on Mars. You've been a Martian, so to speak, for a long time now. But you've also worked with some people who've been doing this even longer. I mean, I looked at your involvement with the Themis camera on the Mars Odyssey orbiter. Phil Christensen, old friend of this show, along with Jim Bell, who you still work with, who is, of course, the principal investigator for Mastcam-Z.

And you worked with him on the Curiosity rover. This is something that there are so many people that have been looking forward to for a very long time. I'm wondering how you think our entire history at Mars, orbiters and rovers and just landers, have led us to this moment. Well, I think that's absolutely true that everything is built up to Mars 2020. I mean, the reason Mars is an interesting planet from so many perspectives, but ultimately the reason that space agencies all over the world have been so focused on it for the last 50 or 60 years is because Mars offers the promise of a place that was at least at one point in its history, very Earth-like. It was very much like home. And that means the kind of life you might be looking for might be Earth-like. We know how to look for it. We know where we should go to look for it in theory. And so that's

really what's been driving the Mars exploration program for so long now. Now, everything from, you know, Spirit and Opportunity just verifying that, yeah, there was watery environments. There were lots of different diverse watery environments on the surface. Curiosity, with its enhanced payload, was able to tell us things like, there are organics in these sediments. There are organics that could have been the building blocks of life that are present. And now finally building up to the point where we think we know enough to actually choose a site to go look for ancient biosignatures in the rocks on Mars, which is an incredibly difficult prospect. It's difficult here on Earth, right? People are still arguing over what are the most ancient signs of life in the rocks here on Earth. Even when we can go out and look at where they

came from, we can throw them in any laboratory on Earth and try to figure out what's going on. Even with all that information, it's still a really hard prospect. So we're really hopeful that we know enough about Mars to at least give it a shot. We think we have the best chance we're going to have with the information we have to look for life on Mars. And so I think everything we've done from the rovers in the past, even going back to, you know, a little sojourner and just showing us that, yeah, we can rove on another planet, all the way through the scientific beast that is the Curiosity rover, I think really built us up to this point. I think, really built us up to this point. Where do you expect to be on February 18th, 2021,

during those seven minutes of terror as this new rover descends to a crater called Jezero? Well, I hope to be at the Jet Propulsion Laboratory with as much of the Mars 2020 team as we can get there. I think that'll be an incredibly exciting experience. I went to Curiosity's launch, but I've never been to a landing. And so I'm really excited to be part of the team. Well, I hope to be not too far away.

Maybe we'll be doing one of our big Planet Fest celebrations, watching all of you jump up and down when this new rover sets foot on the red planet. And we will be doing the same. And many more conversations about what's ahead between now and this 2020 launch. Brioni, thank you so much for taking us through this very important decision that has just been made. Thank you. We've been talking with Bryony Horgan. She is an assistant professor in the Department of Earth, Atmospheric, and Planetary Sciences

at Purdue University in Indiana. And as we said, she's a co-investigator on the Mastcam-Z instrument, that main camera system that will be going on that rover to the crater called Jezero. But she has been helping us to learn more about Mars, leading up to looking for signs of life there for a long time. Time for What's Up on Planetary Radio. It's time to talk to the chief scientist of the Planetary Society. Bruce Betts is that guy. Welcome back.

Thank you. Good to be back. Looking forward to joining you on stage at that big inside event at Caltech, which may very well be sold out. So we don't have much reason to promote it. It was sold out, and then they decided to open up the balcony. I'm hoping that as people hear this and if they want to come and join us at Caltech on the morning of Monday the 26th, that they might still be able to be there. But you'll be there. Oh, good.

So they will let me in? Yeah, they'll let you in. And we're going to save a seat for you on stage. Okay, good. I hear that as the best view. Well, not really because the big screen will be behind us and over our heads. Oh, yeah, but I want to look at the people. Yeah, okay, then you're in good shape.

What do you want to look up at the night sky? Well, you know, northern winter is coming because Orion is coming up in the evening now, coming up in the mid-evening over in the east with its bright belt and Rigel and Betelgeuse and all good stuff. So look for that in the mid-evening over in the east. And then in the west in the early evening, you can still catch Saturn low in the west. And then Mars still looking pretty bright despite fading, looking bright and reddish in the southwest. In the morning, it's a party with Venus hanging out still near the blue star Spica. And on December 3rd, the moon will be hanging out with both of them. I always enjoy the night sky in the late fall, winter, because I can look up and say, see, there's Orion and sound like I probably know the other constellations.

Shh, don't tell anyone. Oh, yeah. All right, we move on to this week in space history. It was 2011, 2011 that Curiosity launched on its way to Mars. Wow, that's amazing. Since we were talking in this show about finally sending something else there to join it roving around on the surface. It's been since 2012, right, that it landed? Yes, yes.

Since we've had a successful lander, it's been six years. All right, we move on to... Random Space Fact! It's short and sweet. I don't know if you've ever looked at pictures of the Crab Nebula and thought, hey, that doesn't look like a crab. Here's the story. So first of all, hey, that doesn't look like a crab. Here's the story. So first of all, Chinese astronomers recorded the new appearance of a very bright star in 1054 AD,

visible even in the daytime. The Crab Nebula is located where the Chinese astronomers said the bright guest star appeared in the sky. Now the name Crab Nebula is due to a drawing of the nebula that looks sort of, but I looked at it and I don't see it, like a crab made by William Parsons in 1840. Ever since, it's been known as the Crab Nebula. That's a great story. Thank you. You're welcome. We move on to the trivia contest. And I asked you, well, I noted that Dawn very successfully employed ion thrusters for

propulsion. What was the first spacecraft to employ ion thrusters beyond Earth orbit? How'd we do, Matt? Well, as I said two weeks ago, I'm always pleased when I know one of these off the top of my head. Right there on the top of my head, someone stenciled Deep Space One. Yeah, that was me. You shouldn't have fallen asleep at the office. Yeah, that's always a mistake. Deep Space One, good. And our winner is Jack Shropshire.

Jack Shropshire in Rancho Cucamonga, you Jack Benny fans out there, who indeed said it was Deep Space One. He added, ion engines will be even more valuable post-singularity when we can just send our consciousness to the stars on CubeSats. Running tiny supercomputers slow down so millennia feel like days to the astronauts. Okay, Jack, you're way out there, but you're still the winner. And what he has picked up is a copy of your book, among other things. That's a boost.

New book, Astronomy for Kids, now available online and everywhere. All the places you usually get good books. And it's very cool. We've talked about it many times. Also, a Planetary Radio t-shirt and a 200-point itelescope.net account, which will come in handy after Jack reads Astronomy for Kids, because it's not just for kids, is it?

No, no, it's really for everyone. But it's got that snazzy title. But it's really for anyone looking, I don't know, to learn constellations besides just Orion. Here are some other great things we got. This one from Narahari Rao in Sugar Land, Texas. We've heard from him before. We know, of course, that these ion engines in Deep Space One, and for that matter in Dawn, they use xenon, right, as their propellant? They do indeed. Well, he says at about four and a half times the density of air, xenon is the heaviest non-radioactive inert gas. More mass implies denser packaging.

With a high mass to ionization energy ratio, it's easier to ionize as well. Hence, it is the ideal propellant. And it's easier to ionize as well. Hence, it is the ideal propellant. And it's tasty. Yeah, don't try it at home, please. That would be a noble experiment. Norman Kassoon in the UK, he said, record-breaking use of solar electric propulsion on Deep Space One achieved 27,700 miles per hour, 2.7 times any prior spacecraft, nearly equal to the velocity provided by Dawn's Delta launch vehicle. That's pretty cool. Torsten Zimmer, I always enjoy hearing from Torsten in Germany. He said, and there were a lot of these Deep Space Nine references. Deep Space One was decommissioned in 2001 and since then has only been visited by a handful of aliens who had been duped into believing they'd find Cork's Bar at the location.

Nick Chury, Scott Plains, New Jersey. Deep Space One visited the asteroid Braille and the comet Borelli. Neither one, unfortunately, is an alien light sail spacecraft observing Earth. How do you know, Nick? Well, we do know, don't we? Because we looked up close at them, thanks to Deep Space One. Finally, Richard Hoffman in Greenport, New York, who says, hey, instead of rock, paper, scissors, can we play Comet, Stony Iron, Carbonaceous Chondrite?

Ooh, that sounds fun. That's it. We're ready to talk to you about another one of these. Here we go. It's going to be kind of long, but kind of interesting. The answer's long. The question's short. What chemical elements were named after celestial bodies or the gods and goddesses for whom the bodies were named? Go to planetary.org slash radio contest. You've got until the 28th. That'll be November 28th, Wednesday at 8 a.m. Pacific time to get us this answer. And we got a nice little holiday package for you here in addition to a Planetary Radio t-shirt, which you can check out in the Planetary Society store at chopshopstore.com

and a 200-point itelescope.net account, that great worldwide network of telescopes that you can use to look anywhere in the sky, anywhere around the Earth. We're going to throw in a copy of the terrific kids' book, Max Goes to Mars, by friend of the show, Jeff Bennett. We haven't given away one of these in a while. It's really fun and I think was kind of a children's literature bestseller, Max Goes to Mars,

part of that series of Max theseller, Max Goes to Mars. Part of that series of Max the Dog books that Jeff came up with. Lots of good science in there. Not a bad package, is it? No, it sounds good. Sounds fun. All right. With that, then, I guess we're done. All right, everybody, go out there, look up the night sky, and think about

if you had the opportunity, what would you stencil on Matt's forehead? Thank you, and good night. That's fine. You can write whatever you want on my forehead. Just don't put my hand in warm water while I'm napping, please. He's Bruce Betts. He's the chief scientist for the Planetary Society who joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its Martian members. Mary Luz Bender is our associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser.

I'm Matt Kaplan, though Twitter knows me as AtPlanRad. Add Aries, everybody.