“Houston We Have a Podcast” is the official podcast of the NASA Johnson Space Center, the home of human spaceflight, stationed in Houston, Texas. We bring space right to you! On this podcast, you’ll learn from some of the brightest minds of America’s space agency as they discuss topics in engineering, science, technology and more. You’ll hear firsthand from astronauts what it’s like to launch atop a rocket, live in space and re-enter the Earth’s atmosphere. And you’ll listen in to the more human side of space as our guests tell stories of behind-the-scenes moments never heard before.
Episode 18 features Doug Archer, Planetary Scientist, who talks about Mars: what it’s made of, what it’s like on the surface, and why it’s such an intriguing place for humans to visit in the next giant leap. This episode was recorded on April 10, 2017.
Transcript
Gary Jordan (Host): Houston, we have a podcast. Welcome to the official podcast of the NASA Johnson Space Center, Episode 18: Mars. I’m Gary Jordan and I’ll be your host today. So this is the podcast where we bring in the experts– NASA scientists, engineers, astronauts– bring them right here on the show and talk about all of the coolest parts about space. So today we’re talking about Mars with Doug Archer, which I feel like is a good topic to bring up now because next week, NASA is launching a brand new podcast called “Gravity Assist” hosted by Dr. Jim Green, NASA’s Director of Planetary Science. The show will focus on planets, and the solar system, and beyond. So if you love planetary science, definitely subscribe to that show. It’s going to start with a ten-part series on our solar system that starts with the Sun and goes all the way out to Pluto and beyond. I know I’m pretty excited about it. So as sort of a taste of what you’re going to get on “Gravity Assist,” Doug Archer will talk about the fourth planet from the Sun today on “Houston, we have a podcast.” Doug is a planetary scientist at the NASA Johnson Space Center here in Houston, Texas. And we had a great discussion about the Red Planet– what it’s made out of, what it’s like on the surface, and why it’s such an intriguing place for humans to visit in the next giant leap. So with no further delay, let’s go light speed and jump right ahead to our talk with Dr. Doug Archer. Enjoy.
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Host: So you’re a planetary scientist. That’s your title, right– planetary scientist?
Doug Archer: Yep.
Host: So I’m guessing it’s exactly what it sounds like– you know the science behind why a planet is the way it is– why it’s a planet and how it works and all that kind of stuff. Your specialty is Mars.
Doug Archer: Yep, yeah, I’ve been working on Mars for about 13, 14 years now.
Host: Wow. So what was it that originally fascinated you with Mars?
Doug Archer: So like lots of kids, when I grew up I was interested in space or being a pilot or something like that, or an astronaut. But then when I was, I think, 16, I read a book called “the case for Mars: the plan to settle the red planet and why we must.” And it was written by a guy named Bob Zubrin, and he laid out this whole architecture for how we would get to Mars, the type of rocket that we would need, what the habitats would look like, how long it would take to get there– just this whole architecture of how we would get to Mars, and then ultimately, the long term goal is turning Mars into a more earth-like place. But that’s like the super long term goal.
Host: Right.
Doug Archer: So this book came out, again, I think, in 1996 or something like that, and there was this big cover article in “Newsweek” and other magazines– it kind of made big news. And I just read the articles, read the book, and just got fascinated with the idea of human exploration of Mars, and then learned more about the planet Mars. And when I was an undergrad, I was trying to figure out what major I wanted to do, what I wanted to major in, and I was thinking about, “well, you know, I think I’m kind of good at this, and I’m kind of good at this.” But what I was really passionate about was Mars and Mars exploration. And I didn’t know how to make a career of that, because where I went to undergrad at Brigham Young University in Utah, we didn’t have any kind of space related program there. So I ended up just majoring in physics. I found a professor who was similarly interested in Mars, and another professor in the geology department who’d actually–
Host: At Brigham Young?
Doug Archer: Yeah, at BYU– there just happened to be a few other kind of space enthusiasts there, Mars enthusiasts. So they kind of pointed me on the road, and so I took an introduction to planetary geology course as an undergrad, and just loved that. And they pointed me on the course of, “all right, here’s some courses to take to prepare for grad school, and this is where you should apply.” And one of the places that I applied was the university of Arizona, which has one of the few programs in planetary science in the country, or one of the few PhD programs. And I got accepted and started there in august of 2004. And the reason that I went there is that they had just won the contract from NASA to do the 2007 Mars phoenix scout mission.
Host: Huh.
Doug Archer: So I got to see– so I went in, and my advisor was the principal investigator for that mission, so kind of the boss over the whole mission. So I went in as a first year grad student and worked on the phoenix project right after it had been selected. And so my career as a grad student spanned the right after selection, all of the design work, verification, all of that for phoenix, and then landing, surface operations, and then doing the science on the stuff that we learned on the surface. And the mission ended in late 2008. So I just kind of walked into this great opportunity of getting involved in an actual Mars mission as a graduate student, and just loved working on Mars, loved the mission operations aspect of it, and one of the most exciting times of my life has been the two times when I’ve been able to remotely witness a robot landing on Mars and just the absolute thrill that that is the 10 to 15 minutes of, okay, this is it. Everything comes down to this moment, and then the thrill of seeing the first pictures from these landing sites that no one has ever seen before. Like it is just an absolutely amazing experience to see these pictures coming in for the first time from another planet and just having that feeling of discovery and exploration.
Host: I can imagine, because you have such a passion for it, since you pursued it so far, getting a PhD. And in planetary science, being fascinated with planets and then being able to work on and learn from a robot that was actually on the surface of another planet.
Doug Archer: Yeah.
Host: That is crazy. That is awesome. So that makes me think– why– so your specialty is Mars, and that is a huge part of NASA’s journey to Mars, right– we really want to put boots on that planet.
Doug Archer: Yeah.
Host: But why that planet? Obviously we have Venus, we have– titan looks pretty cool, and Enceladus. What is it about Mars that’s so intriguing?
Doug Archer: So as far as the boots– it all kind of comes back down to the boots on the ground aspect that you’re talking about. Like titan and Enceladus are very interesting places, Europa– there’s other really cool places in the solar system, including if you’re looking for life outside of earth. There’s other places that you could go look. Mars is the planet that is the most likely to host life where humans can actually go. Like, we are years and probably decades and centuries away from being able to safely go to Enceladus or titan or Europa or whatever with people.
Host: That’s pretty far away.
Doug Archer: Yeah, we have the technology to get us to Mars, and I think that it is– we know that in the Martian past Mars was a lot more earth-like than it is today. We don’t exactly know how that happened. It’s still an open question as to how Mars could have sustained this warmer climate, for various reasons that we could get into.
Host: Yeah.
Doug Archer: So we don’t exactly know why that’s the case, but we know from geologic evidence that Mars was warmer and wetter in the past than it is today, and we know from earth that pretty much as soon as life could have existed on earth, it did. So we don’t know how life originates, exactly, but again, from earth we say, hey, as soon as the conditions were right for life to exist, we find evidence of life. We know that those same conditions existed on Mars, so the question is can we go to a place where we can find evidence of a past– more likely past but potential present life on Mars. And then as far as the astronauts, the astronauts will allow you to do a lot more science than robots will.
Host: Right, because it– I mean, so we talked about this on a previous episode with Bill Foster about space communication.
Doug Archer: Okay.
Host: And how difficult that’s going to be. If you get a signal to Mars, it’s going to take 8 minutes, up to 40 minutes’ round trip to do anything.
Doug Archer: Yeah.
Host: But if a human was there, they can make decisions rapid-fire.
Doug Archer: Yeah.
Host: You can get a lot more done in a shorter amount of time. I’m guessing that’s like pretty much the basis of why humans are that much better– probably also the observational aspect of it.
Doug Archer: Yeah, absolutely, both of those things together. So let me– I’ll give you an anecdote to kind of show you the limitations of robotic exploration. And first I’ll say– talk about the benefits of robotic exploration. First of all, it’s something that we can do today, right– we’ve been doing it on Mars now for over 40 years. The Viking landers landed in late 1976. So we have a lot of experience operating robots on the surface of Mars, and they are very capable. Like, the rovers can hold a lot more stuff than astronauts can. They don’t have to continually go back to the the hab. You don’t have to send food. You don’t have to worry about oxygen.
Host: Right.
Doug Archer: So it’s a lot simpler. However, robots are only as smart as the humans that program them.
Host: Right.
Doug Archer: And because we have no capability of repairing or fixing something if it goes wrong, we’re very cautious about how we operate the rovers, or robots. And as you said, we have this communication issue built in that makes it so that– you know, a lot of people think that when we’re operating the rovers on Mars, it’s a man or a woman sitting in a room somewhere with a joystick in front of a TV and driving the rover.
Host: Right.
Doug Archer: But at its closest, Mars and earth are– there’s a four-minute one-way light time delay between Mars and earth, so eight minutes round trip. And at their farthest away, it’s about 20 minutes one-way or 40 minutes round trip. So you can imagine, anything that you’re seeing is delayed by 40 minutes. So there’s no way– in the worst case– 8 minutes, best case– there’s no way that you can do any kind of real time operations under those circumstances. So what we do is we plan a whole day at a time. So during the Martian night when the rover is asleep, we’re awake planning the next day. And when the rover wakes up, the first thing it does is kind of check in with earth and get the instructions for what it should be doing that day. And then it will go through the whole day of planned operations, and then go to sleep, and then the process repeats– wakes up– and so it sends back the data of what it did that day, we look at the data of what it did, how things went, and then plan the next day. So because of our conservatism, because we don’t want to break anything, and because the robots are only as smart as we make them, you’ll have funny instances where, for example, the phoenix lander, which we knew had a very limited lifetime because it was in the northern polar region– so at some point, the sun was going to set and not rise again for six months. So there’s nothing that we could’ve done to make that mission last for years. We knew that going in.
Host: Because– how cold does it get when the sun sets?
Doug Archer: When the sun sets for kind of months at a time, I think it can get down to like minus 130, which is the frost point for carbon dioxide.
Host: Fahrenheit?
Doug Archer: So the Martian atmosphere– Celsius, sorry. But at that point, they’re relatively similar. But so the Martian atmosphere is 95% carbon dioxide, and it gets so cold that the atmosphere starts condensing out onto the surface as dry ice. So our lander, at the end of the Martian northern winter, was buried under a meter of carbon dioxide ice.
Host: Okay, so no coming back from that.
Doug Archer: Yeah. So we took pictures with high res– a high resolution camera around Mars, and it looks like one of the solar panels, which is kind of the size of a kitchen table on the lander– it had two panels about that size, and then a lander itself that was about the same size. And it looks like one of the solar panels was broken by that.
Host: Oh.
Doug Archer: So we knew that there was almost no chance that we were going to survive to the next year. We knew that going in.
Host: But the polar ice caps are– they’re super interesting. That’s why you sent it there, right?
Doug Archer: So we were just south of the permanent ice caps, but– so there’s the seasonal cap of co2, and then water ice as well.
Host: Cool.
Doug Archer: But then the reason why we chose the location to send phoenix is that underneath– or we saw from orbit the signature of water underneath soil. And we went to confirm that, and we did, in a few ways. One was just during the landing process. Our thrusters that we use to land safely blew off the covering of the soil or loose dirt right underneath the thrusters, and you can see this ice-cemented ground. Then we had a robotic arm to dig down, and found that depending on exactly where we dug, between 4 and 15 centimeters deep we found this ice layer where in a couple places it looked like it was almost pure water ice. And most of the area that we uncovered was ice-cemented soil. So you can imagine taking a dish full or dirt, adding water to it, and throwing it in the freezer. And at these temperatures or at the Martian temperatures that I was talking about earlier, it’s as hard as concrete.
Host: Really hard to dig, then, probably.
Doug Archer: Yeah, so we couldn’t dig into that. The best we could do, we could kind of scrape along the surface and collect what we scraped. But we also had a drill that could drill about a centimeter into the ice, and then we’d collect the tailings that came from the drill.
Host: Okay.
Doug Archer: But to get back to the human exploration plan, so one day on Mars, we’re digging with the phoenix lander– and so what you do, right, you say, “okay, dig here, and then dump here.” So dig in this area that we define, and then dump off in some other area.
Host: On the surface, right? Not–
Doug Archer: Yeah, all on the surface.
Host: Okay.
Doug Archer: So the arm is digging, and it goes to dump, and it just so happened to choose a path between the dig location and the dump location that there was a rock in between– it wasn’t a big rock. I mean, it was maybe 8 to 10 centimeters across– not a huge rock. But so on like the very first scoop– and it was supposed to be– supposed to scoop for a while. On the very first scoop, it grabs a scoop of dirt, hits the rock, and just stops. Because it doesn’t know what to do, right? And we didn’t program it to say, okay, well, if you hit a rock, then try this other path.
Host: The only thing it knew was okay, you go from here, and you go to here. It wasn’t expecting an interruption.
Doug Archer: Yeah, so that’s the kind of thing– and then you go in the next day and you see that, wow, things didn’t go as planned. We only had this one tiny little scoop. There was supposed to be a whole trench there– what happened? And you go look at your telemetry and say, “oh, we hit a rock.” And it wasn’t even a very big rock. And that’s the kind of thing where for a human, right, “oh, I hit a rock. I’ll slightly move my hand and go around the rock.” And you don’t waste an entire day from hitting a small rock. And we encounter stuff like that all the time, because again, the robot’s only as smart as we are. If we encounter something unexpected, the conservative approach is usually to say, “okay, just stop, and we’ll tell you what to do tomorrow.” So a human doesn’t have those kind of limitations. As you’re saying, we have the observational ability to first of all analyze the landscape and say, “those look like the most interesting places to go investigate. Let’s go there.” And then you can go do things very quickly. And so the pace of exploration with humans can be a lot faster. Now, the cost is also a lot higher.
Host: Sure.
Doug Archer: So you’ve got to figure out kind of what’s your science return per dollar. But the pace of explorations with humans can be much, much faster.
Host: Right.
Doug Archer: So like, as another example, the curiosity rover, the Mars science laboratory, which has been on Mars now for almost five years.
Host: Wow, that’s right.
Doug Archer: We have driven just over 16 kilometers, which is a long ways, but for a human and a human class rover, that would probably be a good day or two of driving.
Host: Right.
Doug Archer: Now, you know, we’ve done a whole lot of science along the way, so you can’t– it’s not just we landed and we’ve been doing nothing but driving.
Host: Hit the gas pedal and just go for–
Doug Archer: For five years, yeah. But just to give kind of a sense of scale. I think we– the opportunity rover relatively recently surpassed how far the Apollo astronauts had driven on the moon.
Host: Wow.
Doug Archer: And so I think it took opportunity over ten years what the Apollo astronauts did in like three days.
Host: Right.
Doug Archer: So you can see that there’s a sense of– there’s this difference in scale of kind of what you can accomplish, and it’s interesting, that you’ll find that a lot of people that have experience with robotic exploration, actually operating the rovers, many, many, many of us are big proponents of human exploration because we understand the limitations, because we know just how much more we could learn and how much more we could do with humans there.
Host: Yeah. So I’m getting– so as a planetary scientist– I guess we should’ve addressed this a while ago, but you– do you pick the locations where the rovers are going to go? And which rovers are you kind of working with now? Are you working with curiosity?
Doug Archer: Yeah, so right now, I’m working with curiosity. The only other rover that’s currently operational is the opportunity rover.
Host: Right.
Doug Archer: Which is amazing. It’s been going for more than 13 years now.
Host: Yeah, way past its expected–
Doug Archer: Yeah, the prime mission was supposed to be 90 days. So they’re like 4,000% of lifetime or something– I forget the number.
Host: Awesome.
Doug Archer: But much, much, much longer than they ever expected, which is just great, and a testament to the engineers that built the rover. So I work on curiosity, and the way that the landing site selection process works is it’s actually a fairly democratic process. They’ll have multiple meetings for years in advance of launch for scientists to come, and you can propose to land wherever you want. You can say– well, okay, within reason. So the engineers will say, “okay, for this lander it needs to be within 30 degrees of the equator, or 45 degrees of the equator,” or whatever, and you have to be able to fit a landing ellipse that’s this size. And so the landing ellipse defines– is the area in which you are confident your lander is going to land. So, say, for the MER rovers, the landing ellipse was like 100 kilometers long and — I don’t remember– 15 kilometers wide or something like that. So you’d have to say, “all right, you have to find a place where we can safely land anywhere inside of a 100-kilometer-long ellipse by 20 kilometers wide. And MSL, because we got better at guidance during entry, the landing ellipse was only like 12 kilometers long I think and a few kilometers wide. So a factor of 10 improvement over what we’d done before, which opened up a whole host of other landing sites.
Host: Because now you don’t have to worry about things being in the way.
Doug Archer: Yeah, you don’t have to–
Host: A hundred kilometers kind of ellipse.
Doug Archer: You can pick a lot more interesting places because your safety requirements are relaxed from just kind of the physical geography standpoint.
Host: Mm-hmm.
Doug Archer: But so given those restrictions, you can propose anywhere you want.
Host: Mm-hmm.
Doug Archer: And you can– so you’ll go and you advocate, you make your presentation, and you advocate for this particular site, and why your site is better than any of the other ones, the questions that we’re going to address by landing there, why this site best meets NASA’s goals and the goals of the planetary science community. And so, I mean, I think they start out with a list of like 30 to 50 landing sites, or something like that. And over time it’ll get narrowed down to usually around 3 or 4. And then what happens is there will kind of be like a community consensus around, “this is our top pick.” So that’s kind of the democratic side of things, but then ultimately the decision is made– I’m not exactly sure who, but program officer level, NASA headquarter level, where they’ll say– because sometimes a scientist will pick things that are like, “this is really interesting, but it’s a little bit riskier than some other site.” And for the scientists we say, “yeah, we want to do it.” And NASA headquarters might come in and say, “guys, it’s a lot more important for us to land safely then to answer this particular question.”
Host: Right.
Doug Archer: “so we’re going to choose this site.”
Host: Okay.
Doug Archer: But for the most part, it’s very democratic about basically anybody with a good idea can submit a candidate landing site, and then it gets talked about in the community for years. You analyze it for safety. We actually use our orbital assets that are around Mars now to take a lot of pictures of it to make sure for safety reasons that it’s safe. Like, another little anecdote with phoenix we had one– we had four candidate landing sites and the top, I’m almost positive if I’m remembering correctly, the top– we had decided on one landing site of, “okay, we think this one’s going to be the best.” And then we had the HiRISE camera get to Mars kind of right at the tail end of this process. So we didn’t have the high enough resolution– we didn’t have as high a resolution pictures as we do today. So HiRISE, one of its top priorities was evaluating these phoenix– potential phoenix landing sites. And this one that we had decided was going to be our top site, the principal investigator of the HiRISE image– instrument, which is also built at the university of Arizona, where the phoenix lander was. The PIF HiRISE was a good friend with the principal investigator of phoenix and he sent an email with the picture of this landing site and it was filled with massive boulders. There were just below the limit of resolution of this other camera and it would’ve been an awful, awful place to land. So at that point, like okay, all of the other arguments are thrown out because it’s not safe.
Host: Oh, yeah.
Doug Archer: And so we went to I think plan b and they imaged that one and it was like, “yeah, that one. That one looks good.”
Host: Wow. Okay, that would’ve been– yeah. That would’ve been not good.
Doug Archer: I mean, I think as I recall, we got the image around Halloween, so he sent it with the caption of like, “happy Halloween.” And the whole thing was like shaded red or orange or something to make it look even scarier than it actually was.
Host: Wow.
Doug Archer: So yeah, at that point we knew, “okay, that’s not– we’re not going to land there. Let’s go somewhere else.”
Host: Wow. So, I mean, there’s rovers all over the place, right? It’s just you said we’ve been landing on Mars since the late ’70s, since ’76 I think you said was the Viking, right?
Doug Archer: Yeah.
Host: So there’s a lot of interesting things about Mars. So, I mean, main question, right, so if you’re looking at Mars and you want to know, “okay, what is this planet? Why is it so interesting?”
Doug Archer: Uh-huh.
Host: Main question: why is it that red or burnt orangey color?
Doug Archer: Yeah.
Host: Like, what is the official color of Mars?
Doug Archer: Well, red.
Host: Red.
Doug Archer: I mean, that’s one of Mars’ nicknames is the red planet.
Host: Right, okay.
Doug Archer: I mean, that’s when I’m writing stuff about Mars I will frequently call it the red planet just to avoid repeating Mars or Martian over and over again.
Host: Yeah.
Doug Archer: So Mars gets its red color really from essentially rust.
Host: Oh.
Doug Archer: So you have– in some parts though– or many places on Mars, it’s interesting, but it’s really only skin deep that you can uncover– or if we go and either brush off or just blow away some of the dust you get to– underneath it it looks a lot darker. But we have this bright dust deposits kind of all over no Mars because Mars can have these global dust storms. So you get this stuff distributed everywhere.
Host: Wow.
Doug Archer: And the red color really comes from the oxidized iron, which again, rust, or hematite, the specific mineral or other things like that that give Mars its red color. So you had oxygen in the atmosphere, which is reacting with minerals on the surface to produce this iron oxide, which gives Mars its red color.
Host: Huh. Is it sharp, the dirt? Or do you call it dirt or do you call it–
Doug Archer: Yeah, soil or– we’re moving towards calling it soil on Mars.
Host: Soil.
Doug Archer: Even though some terrestrial people say, “uh, soils have to have living things in it.”
Host: Okay.
Doug Archer: But we like regolith on the– or the what we’re calling soil on Mars is different from regolith on the moon or other airless bodies.
Host: Yeah, okay. Nice. But there’s oxygen in the atmosphere. Not a lot though, right? Like you can’t step out on Mars out of your– if you were to land on Mars and step out of your capsule and breath the fresh air, right? There’s not a lot.
Doug Archer: Correct. There is– so Mars’ atmosphere is 95% carbon dioxide, 2% nitrogen, and 2% argon, with– so that only adds up to 99%. So then there’s other little bits and oxygen is one of the other little bits, but it’s much, much less than 1% oxygen.
Host: But it’s enough to rust the–
Doug Archer: Yeah.
Host: Make the soil–
Doug Archer: Well, and that’s the idea of– that’s where at some point in the past Mars’ atmosphere probably had more oxygen.
Host: Right.
Doug Archer: An that oxygen reacted with what’s on the surface.
Host: Okay, so compared to earth, our earth is mostly like nitrogen, right, 70% nitrogen and then–
Doug Archer: Yeah, 80%– roughly 80% nitrogen, 20% oxygen inside of the–
Host: Okay, okay. So only 20%, that’s awesome.
Doug Archer: But so the other thing though is there’s– you can’t– not enough oxygen to breath, but it’s also less than 1% of the atmospheric pressure of the earth. So really low pressure, no oxygen. There’s a lot of different ways that you could meet a quick end on Mars if you just decided to step outside without any kind of protection.
Host: Which goes to our earlier point is if you were to go there you would probably need a habitat, and you would need rovers, and you need all kinds of spacesuits to walk around.
Doug Archer: Yup.
Host: You’d need all kinds of things to survive on Mars, but– I mean, Mars is not just– it’s not just a blanket of the soil, this red soil. It’s got hills and mountains. It’s got one of the biggest–
Doug Archer: It has the biggest volcano in the solar system.
Host: The biggest volcano in the solar system, right? So, I mean, there has to– there was a past of geological activity, right?
Doug Archer: Yes. Yeah, absolutely. So when we look at the history of Mars, we see a lot of evidence early on, like I was saying earlier, that Mars was warmer and wetter than it is today. Now, it’s still an open debate about how warm it is and how wet it was, but we know that it’s warmer and wetter because we see evidence for rivers and lakes.
Host: Mm-hmm.
Doug Archer: So there was likely at the very least snow, possibly rain, but– and these– I mean, these aren’t like little streams. Large channels, huge lakes. It’s possible that there was a massive ocean. So we know that Mars was warmer and wetter in the past, and then kind of after that Mars dries out, and then you have all this abundant evidence of what you’re talking about, the volcanic activity. Really, I mean, all over the place on the surface if the planet that has really kind of resurfaced a lot of Mars. We see– we still see a lot of craters, but there’s volcanic activity all over the place, like you said. So we have Olympus mons, that’s like 20 kilometers high, the biggest volcano in the solar system.
Host: Super big.
Doug Archer: So MSL, or the curiosity rover, landed at the bottom of the gale crater, which is 150-kilometer-wide crater that’s 5 kilometers deep. And right in the middle of the crater is a 5-kilometer-high mountain. So that’s– I mean, this is– it is a mountain. It’s not a hill.
Host: Yeah.
Doug Archer: It is huge.
Host: Wow.
Doug Archer: I mean, this is– it’s like rivals Mount Rainier or Mount Shasta or something. Like, it is big.
Host: Okay, yeah.
Doug Archer: It’s really big. It would be one of the largest mountains in kind of the lower 48 united states.
Host: Wow.
Doug Archer: And it’s– we’re still kind of trying to figure out exactly how it was formed. One of the interesting things about it is that it was– it was not formed by– so, most mountains on the earth are formed through plate tectonics, right? The continental plates kind of crashing against each other. Or a subduction of an oceanic plate pushing up mountains and that’s how we get mountains on the earth. On Mars, we don’t really have plate tectonics, so you can form mountains either from volcanoes. There might be some tectonic activity, but what we’re seeing in mount sharp is likely the result of actually the crater, to some degree, filling up with sediment, so dirt, rock, whatever, around a pre-existing central peak in the crater that we still see some evidence for. But what the mountain that we see is much, much larger than the central peak would’ve been. And then, eroding away into the shape that we see today. So completely different form of– or completely different formation mechanism for a mountain. I don’t– I can’t think of example or any place on the earth where you would ever see anything like this.
Host: Wow.
Doug Archer: But still, we formed this 5-kilometer-high mountain, and the cool thing about it though is because it is this composed of sedimentary layers that were laid down over hundreds of millions of years, as we drive up the mountain we are seeing different– we are seeing different layers and we get a window into Mars’ geologic past. So we could learn something about what was Mars’ environment like 3.5 billion years ago. And the reason that we picked this location is that the lower part of the mountain was created when Mars was warmer and wetter and the upper part was created when Mars was colder and dryer. So we’re going to have the opportunity to drive across these materials where that spanned again hundreds of millions of years of geologic time.
Host: You’re kind of like driving through time, yeah.
Doug Archer: Where Mars went under this– yeah. When Mars underwent this fundamental geologic change– or climate change. So trying to figure out what happened.
Host: It’s kind of like– so I mean, I’m from Pennsylvania, so I remember driving down the highway and seeing they blew up some of the rocks and then you could see the layers of the rocks.
Doug Archer: Yeah. Oh, yeah, rock cuts are geologists best friend.
Host: Yeah. So it’s kind of like, I mean, the mountain itself are those layers of rock as you drive up.
Doug Archer: Uh-huh.
Host: Is– I guess that would be a kind of a good comparison?
Doug Archer: Yeah, yeah. It’s just on Mars it might actually be a little bit easier to interpret some of it because of the earth– again, the mountain, you had the layers– so you had the layers kind of laid down creating the rock and then you’ll have these other tectonic events that push them up. And in the process, things get all kinds of jumbled. But on Mars, there was no tectonism so they laid– the rocks got laid down and then they get eroded away. But there’s nothing that has– that was pushed up from kilometers deeper, or you know, overturned, creating all kinds of confusion. So it’s– if we can get there to the right places– unfortunately, on Mars there is no road cuts so we have to do with– we have to use what we’re given, but it’s very similar to what you’d see in a lot of places on the earth.
Host: Wow. Okay, so another main difference, right, is I guess, the atmosphere. We just had a recent discovery about how Mars’ atmosphere has changed over time, right?
Doug Archer: Uh-huh.
Host: And how– what’s the radiation environment like on the surface?
Doug Archer: So yeah, the atmosphere– so that’s two things.
Host: Okay, okay.
Doug Archer: The atmosphere, again, we know that it was warmer and wetter in the past so that we know that the atmosphere had to be a lot thicker than it is today to hold in that heat. And we’re, again, though we’re still unclear how Mars was able to be as warm and wet as it was. There is something– some kind of magic combination of pressure and chemical elements in the atmosphere that had to of existed to allow Mars to be warmer and wetter. And that’s still something that people are debating today. So how that relates to radiation is that on the earth there’s a few things that protect us from the radiation environment in space. One is earth has a magnetic field that does a lot of the work. The other thing is we have a relatively thick atmosphere, so anything that makes it through the magnetic field is generally going to get stopped in the atmosphere. So Mars doesn’t have either of those things. And there’s other types of radiation as well, so like ultraviolet radiation, which is not great for people. Earth has an ozone layer. Mars, depending on the season, will have a tiny bit of ozone in the atmosphere, but not really enough to effectively shield you from UV. So you get ultraviolet light down to the surface– down to the surface of Mars, which on the earth would be sterilizing. Like, if you’re–you stick a bug– that’s one of the things that we do on earth to sterilize water or whatever, you shine it with UV light that Mars is getting bathed in all the time.
Host: Oh.
Doug Archer: So the very surface of Mars is not terribly hospitable to life. But the good news is, the iron oxides, for example, are very good sunscreen. So if you’re under a couple of microns, so like a human hair’s width of iron oxide will do a pretty good job protecting you from ultraviolet light. So that’s one type of radiation. The other type is, again, the kind of– the space radiation environment where you have these high energy galactic cosmic rays and stuff the sun’s shooting at you all the time.
Host: Oh, yeah.
Doug Archer: So this is something that you have to be– for robots, it’s something that we have to be aware of as well, because we actually have to use special electronics that are, like, radiation hardened. For people, you have a couple things you need to do. One is, you have to have some kind of– some kind of shielding, and then the other is just kind of what your mission architecture is. You want to spend as little time in space as possible.
Host: Right.
Doug Archer: But I mean, what I think, there’s a few things that you can do to shield you from radiation. Like recently– we have a radiation detector on curiosity on Mars. Relatively recently we were right up next to a hill doing some science and the counts in the radiation detector went way down. Because this radiation, it’s not just coming from the sun. It’s coming from everywhere in the sky, basically uniformly.
Host: Huh.
Doug Archer: So if you can block out any part of the sky you’re going to lower your radiation dosage. So if you’re an astronaut you probably want to build your habitat up close to a little hill or a mountain and maybe one of the first things that you do when you get there or you had robots do this before you got there is start filling up sandbags and put it on the roof on your habitat. Because you just need more mass. That’s what the atmosphere is. On earth, it’s just more mass in between the radiation environment and the ground. So you just need more mass on top of you to shield you from this radiation. And then, again, like the UV stuff– an astronaut in a spacesuit will be just fine.
Host: I’m imagining like in “Star Wars,” like Luke Skywalker’s house. How they just had the big dome made of the–
Doug Archer: Little dome on Tatooine.
Host: Yeah, on Tatooine, made of the– it looked like sand.
Doug Archer: Yeah.
Host: So just like making like a sand dome.
Doug Archer: Yeah, so you need something like that, because again, like when we went to the moon, the lunar lander was– I forget, but as I recall, like paper thin, right. Like, it wasn’t a long duration– they weren’t planning on staying there for a long time.
Host: Right.
Doug Archer: So on Mars, if you’re going to stay there for like a year and a half, which is generally the mission architecture says about 6 months trip to Mars to get to Mars, a year and a half on the surface, 6 months back. So if you’re going to spend a year and a half on the surface of Mars you need to do something to shield yourself from radiation once you get there.
Host: Definitely. So in the movie “the Martian” there was a severe dust storm.
Doug Archer: Yes.
Host: From what I understand, that wouldn’t really happen, right?
Doug Archer: Correct.
Host: Yeah.
Doug Archer: And this is– so I got to say though, because not a knock against Andy Weir at all.
Host: Yeah.
Doug Archer: Because when he was at JSC a couple of years ago, he gave a presentation and said, “okay, before you guys ask any questions, I know that the dust storm wasn’t realistic.”
Host: He was probably very nervous about his audience.
Doug Archer: Yeah.
Host: He’s like, “these are the guys that know!” Oh, no. Yeah.
Doug Archer: Yeah, so he just said, “i wanted to write a book about kind of like “Robinson Crusoe” on Mars and I had to do something to get him stranded there.”
Host: Right.
Doug Archer: So the dust storm is not realistic because Mars’ atmospheric pressure, again, is less than 1% of the earth– earth’s atmospheric pressure. So even when you have very fast winds they’re not very strong. So you could have like 100 mile and hour gust and it’ll feel like less– a less than 10 mile an hour wind on the surface of the earth. So it’s just not strong enough to push anything over that size. The other difference is they’re are dust storms on Mars and they can be planet encircling, which is–
Host: Right, yeah. You mentioned that before.
Doug Archer: Yeah, it’s– which is really interesting. Something that obviously doesn’t happen on the earth.
Host: Right.
Doug Archer: Thankfully.
Host: Yeah.
Doug Archer: The way that it works, and you can go look at– there’s pictures of this because the opportunity rover has been there during– I don’t think it was a planet encircling one, but at least a very region, like large scale dust storm.
Host: Mm-hmm.
Doug Archer: And the way that it looks is at the beginning of the dust storm you have– or before the dust storm starts you have pretty clear skies, and then something like 20 to 30 days later you can’t even see the sun at all anymore. It just maybe gets slightly lighter– or brighter during the day. But it’s a very gradual increase from day to day. It’s not like in “the Martian” the “ah! Here’s this massive dust storm barreling down on us. Let’s get– let’s all go inside.”
Host: “it’s tipping the MAV!” Yeah, it was like–
Doug Archer: Yeah, so that was– so Mars does have these really large dust storms.
Host: Right.
Doug Archer: But they’re just not strong enough to really have to worry about much.
Host: Does it have its own weather, too? It has like lightning and stuff, right?
Doug Archer: You know; I don’t know about lightning. It might, I think. I do know of people who have said that it probably does have lightning and the lightning could create interesting chemicals that we see in the atmosphere and on the surface, and so maybe that’s a signature of lightning. I don’t know that we’ve ever directly observed lightning.
Host: Mm-hmm.
Doug Archer: But Mars absolutely has weather. It is still a very dynamic place. The main agent of change on Mars is wind. It just happens at a slower pace than on the earth, but we have– Mars has sand dunes that march across the surface. It has this dust that can blow all over the place. Mars has dust devil, so if you live in a little bit drier, more arid environment and you see a– and you know what a dust devil is, we have– we see dust devils on Mars all the time.
Host: And those the tornado– sand tornadoes?
Doug Archer: Yeah, they look kind of like little tornadoes. Yeah.
Host: Yeah, yeah, yeah.
Doug Archer: Good– yeah. Sand tornado is a good description. And we’ve actually been lucky with some of those. So spirit and opportunity– I know this happened with opportunity. I’m pretty sure it happened with both of them. So they’re solar powered rovers so they saw the output from their solar panels was decreasing over time because you’re constantly getting dust settling out of the atmosphere. And then, so the– I can’t remember the exact numbers, but it had gone down to like half of the solar panel output from when it landed. And then they looked at the data and from one day to the next it jumps back up to the same amount of power they were getting on like day 1 of landing. And so they look at their solar panels and they’d been completely cleaned.
Host: Oh.
Doug Archer: So what they think happened is a dust devil passed directly over the rover and did us huge favor by cleaning off the solar panel. It’s like there’s no way that opportunity would still be alive had that not happened multiple times.
Host: Wow. Okay, so they’re pretty frequent then if they’re–
Doug Archer: Yeah. Oh, yeah. This happens all the time.
Host: Wow.
Doug Archer: And like I– you can actually see the dust devil tracks from space. A friend of mine, Dave Choi, did some work on this where you can see dust devil tracks all over the place, because what I said earlier, you have this bright red dust that gets kind of laid down uniformly over the surface.
Host: Mm-hmm.
Doug Archer: And when a dust devil comes through it’ll suck that up off the surface and move it somewhere else. So you see these tracks of dust devils all over the place.
Host: Oh.
Doug Archer: And at first we didn’t really know what we were looking at. And then somebody, I forget who, said, “hey, those are dust devil tracks.” And yeah, they are all over the place on Mars. We have seen them everywhere– everywhere we’ve been looking we have seen them.
Host: It’s just amazing that you can think of– you can imagine what’s going on at the surface level of another planet.
Doug Archer: Yeah.
Host: As if it’s just like another place on earth, but we’re talking about another–
Doug Archer: On a completely different planet.
Host: Yeah, a completely different planet. That is wild.
Doug Archer: Yeah. And another thing that phoenix saw is we actually saw snow and frost deposition. I mean, it was teeny, teeny, tiny bit of snow.
Host: Right.
Doug Archer: But it was snow, so–
Host: Yeah. It’s kind of like how in– I mean, like I said, I’m from Pennsylvania and we get snow all the time. But here, when there’s snow everyone loses their minds.
Doug Archer: Yes, yeah. It might be– well, so it might snow on Mars more frequently than in Houston. It doesn’t snow a lot.
Host: Oh, I would like to see snow on Mars. That would be pretty cool. So I mean, being a planetary scientist and kind of– I mean, you’ve alluded to a lot, you know, talking boots on the ground, this is what you have to do, this is what have to think.
Doug Archer: Uh-huh.
Host: I’m assuming you’ve thought a lot about what a human mission to Mars would have to look like to be successful.
Doug Archer: From a scientific perspective?
Host: Yes.
Doug Archer: Or a– yeah, so I would say probably the holy grail from a scientific perspective– and this is one of the things that humans would really enable was it would be the ability to drill.
Host: Ah.
Doug Archer: Because, you know, we say– on MSL we have a drill and that’s true, but we can drill down all of 6 centimeters.
Host: Hmm.
Doug Archer: So a couple– like 3 inches, 2.5 inches, so not very far. We are literally just scratching the surface of Mars.
Host: Yeah.
Doug Archer: And if you want to go to a place– again, getting back to the radiation environment, the radiation– you have a lot of radiation or energy deposition in the top meter of Martian soil.
Host: Mm-hmm.
Doug Archer: So any life that existed there that was maybe billions of years old has been either heavily transformed or completely destroyed. So it would be really hard to find the signature of life anywhere within the top meter. So we need to go deeper and if you want to go really deep you need humans. Because drilling is something that is very difficult to do kind of in an automated way even on the earth.
Host: Mm-hmm.
Doug Archer: You need people there to kind of troubleshoot when things go wrong and fix stuff that breaks or whatever. So that to me is one of the things that humans would do. The other thing is, I think we have– we’ve been studying Mars from the surface for 40 years now, but still we’ve only landed in– let’s see, we have Viking lander 1 and 2, pathfinder, MER, phoenix, MSL. So 7 successful landings on the surface of Mars. So that’s like saying pick 7 places on earth, spread out by 1,000 miles or so each, and tell me about the entire planet. And obviously that’s not– like, the whole history of the planet over 4.5 billion years, and by the way, you can only go about 10 kilometers from wherever you land.
Host: Wow.
Doug Archer: So we have– there are so many other places on Mars that we know nothing about. That you look from orbit and say, “what the heck happened there?”
Host: Yeah.
Doug Archer: “What is this? What’s going on there?” And there’s a lot of places from orbit as well where some places we can kind of tell something about the mineralogy. Other places there are completely covered in dust, so we really have no idea what the mineralogy is of what’s underneath it. So another thing that humans will give you is the ability to go farther from wherever you’re starting. And again, the boots on the ground people saying, “hey, this looks really interesting. Let’s chase this down and go there.” Also, we would be greatly benefited by bringing samples back from Mars on purpose where we know where they come from.
Host: Right.
Doug Archer: Like, we have Martian meteorites, but we don’t really know where they came from.
Host: Mm-hmm.
Doug Archer: So knowing the context of the samples and being able to use the instruments that we have on earth, which are much better than the instruments that we send to Mars, because of size, volume, power, or whatever. We could do a lot with a sample returned from Mars and astronauts– like from the moon, astronauts brought back hundreds of kilograms of samples.
Host: Mm-hmm.
Doug Archer: Now, it’s a bit more expensive to get back– or stuff bac from Mars. So we might not have quite as many samples, but we would have– we’d bring– we’d definitely bring back samples with the astronauts. So that’s another thing that having people there on the ground enable you to do.
Host: Yeah. Knowing the science– this will be the last question and then we’ll– and then we’ll kind of wrap up.
Doug Archer: Okay.
Host: But knowing the science of the planet, kind of what are some of the key things that we have to be paying attention for to make sure that humans can survive and operate in the most efficient way? Because like you mentioned radiation a couple times. Radiation is obviously a concern, but what do we have to think about in terms of the way we move and how far we can go.
Doug Archer: Yeah.
Host: You obviously said you already talked about a mission profile how long we can be there.
Doug Archer: Right. So yeah, radiation is one of the big ones. We’re still not totally sure how the human body works for a long period of time in a lower gravity situation. Like, we have people in zero g, right.
Host: Right.
Doug Archer: But Mars is 40% the gravity of the earth. We don’t really know what the effects are of the human body. Unfortunately, that’s incredibly difficult to simulate, so we probably really won’t know until we go.
Host: Right.
Doug Archer: Otherwise, though, there are other kind of environmental hazards that you need to be aware of, like you referred to the dust. So that’s something that you just need to make sure that you have good filtration systems.
Host: Oh, okay.
Doug Archer: It’s– one of the main problems for the dust though is for the suits. Like, if you have a spacesuit with seals and you have joints that move, and you have dust, getting into those joints, which we know it will. It did on the moon.
Host: Mm-hmm.
Doug Archer: Then that can be– that can be problematic. So how do you design your seals? How many replacement seals do you need? Or design your spacesuit to be repairable by the astronauts on Mars. And I mean, but this is also kind of an open question is that we don’t really know the nature of Martian dust. We don’t know if it will be kind of as sharp and damaging as some of the lunar dust, because the lunar dust and Mars dust form in two different ways. Like, we know that– we know the average particle size of the Martian dust that gets into the atmosphere is like 5 microns, but– so that’s great. It’s good to know that, but you need to know a little bit more about the size, shape, hardness, those kinds of things in the dust about the dust when you’re talking to people about seals for spacesuits and spacecraft. The other thing is being aware of potential toxic things on the surface, like perchlorate, for example, which is an oxidized chlorine that– molecule that the phoenix lander discovered in 2008. And so, we know that perchlorate is toxic to people.
Host: Mm-hmm.
Doug Archer: But in really high quantities. So it’s less of a concern for inhalation for people, however much perchlorate might be in the dust. So as I like to tell people, as long as your astronauts are not eating kilograms of soil every day they’re fine. But–
Host: Kilograms of–
Doug Archer: Yeah, it really would have to be–
Host: That’s a lot of soil.
Doug Archer: Yeah, right. So that’s generally fairly low on, “hey, guys, don’t eat dirt.” “yeah, okay, we got it.” We checked that one off.
Host: Very tempting, but resist.
Doug Archer: Yeah, but so the one thing that we do have to– we do have to do more research into is there are– if you grow plants in soil that have perchlorate there are some plants that can concentrate perchlorate in certain parts of the planet. So you need to know, okay, if we’re planning on living off of this, first of all, can it grow in a soil that has perchlorate? And if it does, what– where does the perchlorate go? Is this something that we need to be concerned about.
Host: Mm-hmm.
Doug Archer: So these are– those are kind of questions that we’re answering. But the exciting thing is that we have the data to actually be able to address those questions, right.
Host: Yeah.
Doug Archer: Like, I mean, 40 years ago at the end of Apollo when we talked– first talked about going on to Mars, we didn’t know any of this stuff.
Host: Right.
Doug Archer: We didn’t– we hardly knew anything about Mars, but now we have a significant amount of experience and a large body of knowledge about what the surface of Mars is like. What– all the stuff we talked about today. What is the weather like? What’s the temperature? What’s the pressure? What’s the chemical composition? What’s the mineralogy? What are the physical properties of the soil? If you want to build something there or land something what’s it like? What are the things that we need to worry about? And that’s what’s really kind of amazing about the journey to Mars right now is that really, for the first time, we have the information to go out. And we know the questions that we need to answer. We don’t know the answers to all the questions yet, but for the most part we know a lot of the questions that we need to answer.
Host: Mm-hmm.
Doug Archer: And I’ll just add one final thing so you don’t think that it’s all bad. There’s a lot of stuff in a lot of the work that we’re doing isn’t just what are the bad things about Mars, but what’s on Mars that we can use for humans to help enable future exploration.
Host: Hey, yeah.
Doug Archer: Like there’s an instrument called moxie and I’m sorry that’s an acronym that I don’t know what it stands for. But basically, it ingests atmosphere and it breaks the carbon dioxide and oxygen– so you’re forming oxygen. Oxygen which the idea is you’d use that for your oxidizer in rocket fuel.
Host: Nice.
Doug Archer: And you can also– one of the things that I’m directly involved in is trying to extract water out of Martian material. So water can be really useful because astronauts need water to drink for food. You can break the water through electrolysis or other ways into hydrogen and oxygen. You can breathe the oxygen. Hydrogen and oxygen can be used as rocket fuels or fuel for a fuel cell. There’s all kinds of stuff that you can do just with water.
Host: Mm-hmm.
Doug Archer: And so, every kilogram of material that we don’t have to bring with us makes it more likely that we will actually be able to go because it lowers the cost and complexity of the overall mission. So we’re trying to figure out from what’s on– what is on Mars today that we can use to our advantage. And again, this is– these are questions that we’re now able to answer based on the exploration work that we’ve done over the past 40 years.
Host: That’s awesome. I’m excited. I want to go to Mars like right now.
Doug Archer: Me, too. Let’s do it.
Host: That was a nice little summary of like all the things we talked about, too. That was great. Well, I think that’s all the time we have. Doug, thanks for coming on the show today.
Doug Archer: My pleasure.
Host: That was awesome. So cool. I learned so much about Mars. I had so many questions and like almost all of them got answered. For the listeners, if you do want to know more, I’d be surprised, but actually there are way more questions. We can talk forever about Mars. But if you want to stay tuned after the music that we have at the end here, we’ll talk to all the sites you can go to and learn more, and maybe you’ll find a question that you want to ask and we’ll tell you how to submit that. So thanks again, Doug, for coming on the show.
Doug Archer: You’re welcome.
Host: We’ll see you maybe next time? Maybe one more time, who knows.
Doug Archer: Sure.
[ music ]
>> Houston, go ahead.
>> I’m on the space shuttle.
>> Roger, zero-g and I feel fine.
>> Shuttle has cleared the tower.
>> We came in peace for all mankind.
>> It’s actually a huge honor to break the record like this.
>> Not because they are easy, but because they are hard.
>> Houston, welcome to space.
[ music ]
Host: Hey, thanks for sticking around. So today, we talked about Mars, the red planet, and everything about it. But when I say everything I don’t truly mean everything. Obviously there’s a lot more. We may do another podcast in the future, but if you want to know more about the red planet right now just go to NASA.gov. Right at the top there’s a little gray bar and you can see the journey to Mars. That’s one of our campaigns and if you click on that tab you can learn all of the new things, all of the new features, and all of the new articles, scientific findings right on that page. So just click on the journey to Mars page to go there. On social media, we’re pretty active. Doug Archer here, dr. Doug Archer is part of the astromaterials group, what we call ARES. You can find them on Facebook, and twitter, and Instagram. And you can also go to the NASA johnson pages– Facebook NASA johnson space center. We’re also on twitter and Instagram. On any of those pages, just use the hashtag #askNASA on your favorite platform, whichever one you’d like, and submit an idea for the show. Maybe you have a question about Mars or maybe you have a new idea or a new question that maybe we can make a whole podcast episode out of. Make sure to mention it’s for “Houston We Have a Podcast” so we know to bring it on this particular show. This podcast was recorded on April 20th, 2017. Thanks to John Stoll and Alex Perryman for producing the episode. And thanks again to Dr. Doug Archer for coming on the show. See you in 6.79 sols. That’s a week in Mars time. You know what, never mind. I’ll just see you next week.