>> From the Library of Congress in Washington, D.C. >> I'm Stephanie Marcus from the science, technology and business division here at the library, and I'm the coordinator along with Sean Bryant for this series. Welcome. We're glad to see so many of you. That's awesome. There are, yes, there are a few more seats, and you're welcome to stand or sit on the stairs anyway. Today we are gathered to stand for Venus, the forgotten, mysterious planet. Venus has been overlooked for far too long. The U.S. sent a probe there in 1962, and that was the first probe sent to Venus, and the Soviets followed with the first landing in 1970, and there have been a few things and some things as recent as 2010, the Japanese seemed to have gotten in on it, but nothing in the U.S. So today's speaker is hoping to change all that. We have Dr. Lori Glaze here, and she's the principal investigator for the mission called DAVINCI. She can tell you what that stands for, but DAVINCI is very cool. So Lori has come from Texas originally. She got her BA and her MS in physics at the University of Texas Arlington. And way back in high school, she met her husband, who's in the back row with the long hair, and he's a rock musician, which is really awesome that he said he would not sing, I'm your Venus. So sorry, maybe afterwards. And Lori went to the UK to get her Ph.D. and followed the guy who was a specialist in what she was interested in, which was originally volcanoes on Earth, and she got her Ph.D. at Lancaster University there in the UK. So without further ado, we will hear from Lori. [ Applause ] >> This is great. I'm so excited to see this many people here that have an interest in hearing about Venus. You don't know how excited that makes me. I want to thank Stephanie and the library for inviting me to come here and talk today about Venus and share with you some of the reasons why I find Venus so interesting and so fascinating. You know, in recent years, there's been so much emphasis on exploring Mars and looking for environments that could potentially have head life in the past. And even more recently, there's been new emphasis on going to the ocean worlds, Europa and Enceladus and Titan, looking for potentially actually finding life in our Solar System. But when we're so focused on Mars and the ocean worlds, we tend to forget about how important it is to really understand that full breadth of planetary evolution that's here right in our own neighborhood, right here in our own Solar System. Venus is a natural laboratory right next door to Earth, very close by, that provides a great opportunity for understanding how a planet that maybe once was habitable, shown here on the left, back about 4 billion years ago when we think Venus used to be a host, a home for vast oceans. How does a planet go from this environment that was wet and comfortable and perhaps habitable, how does that evolve over time into this dry, hot, inhospitable Venus that we know today? So that's what I'm going to talk about here today a little bit. Fascination, man's fascination with Venus has been around for millennia, right? I mean, the earliest astronomers were absolutely fascinated by Venus, by all of the planets, because they tended to wander around the night sky, not like the stars that seem to be relatively fixed and move in a predictable fashion. But Venus seemed to wander around like the others. And in addition to that, it was also the brightest object in the night sky other than the Moon, which caused some fascination. And it was unique in the way that it would jump back and forth. First it was the evening star, and then it's the morning star. And then it's the evening star and then it's the morning star. And it does that because it's inside of Earth's orbit. And so we can only see it as we're looking towards the Sun. So we see it just after sunset or just before sunrise. In fact, it has a unique kind of synched up orbit was Earth. This is an unusual fact that you can impress your friends and colleagues with. Venus, it actually is almost exactly linked with a 13-year cycle for Venus with an 8-year cycle from Earth going around the Sun, almost to the second. So every eight years on Earth, we see exactly the same pattern in where we see Venus in the night sky. If you're interested in seeing Venus, now is a good time to see Venus. She's actually visiting us in the morning sky right now. In fact, today I believe is the highest point in the sky. You'll see her right before sunrise. As we move forward in the next coming weeks, Venus so going to keep rising a lit later and later in the morning, so it gets a little lower in the sky by the time the Sun comes up. And then in about December, Venus is going to disappear from our vantage point. Venus is going to go around behind the Sun. So we won't see it for a few months. And then in about February, Venus is going to reappear in the evening sky and go through this whole cycle all again. There's, I think, well, there's no more places to sit. I guess it's the floor or nothing. Sorry about that. But again, I'm really excited to see you all here. A few more fun Venus facts. Do you want to give up your seat? [ Inaudible ] Yeah, if there's someone that needs a seat, let's make sure we get them one. A few more fun facts about Venus. As a starting point, Venus is almost the same size as Earth. This is one of the reasons why we find it so fascinating because it starts out, you think, well, it's about 85% the size of Earth, it's about 90% of it's mass, about 90% of it's gravity, but right there is about where the similarities end and things start to be a little different from Earth. Another fun fact, the Venus day is longer than the Venus year. What that means is that when Venus rotates on its axis one time, it takes longer for it to rotate on its axis than it takes to go all the way around the Sun, to make that whole trip around the Sun. And because Venus rotates so slowly, it's almost spherical. It's different from Earth and Mars, which rotate, in a relative sense, faster than Venus anyway. And they're most oblate. They're kind of squashed because they spin so fast that they spread out at the equator. Well, Venus doesn't do that. It's almost exactly spherical. It also rotates backwards. It rotates retrograde. Why? We don't know. It could be, some people have suggested that maybe Venus rotates backwards, because maybe it was hit sometime in its early history by a giant asteroid, a giant impacter, and that caused Venus to slow down and perhaps begin rotating backwards. But there's also other hypotheses, other suggestions that maybe there's just some probability of 10 to 20% that you're going to get 1 in 8 or 9 planets that rotates the other direction. So we don't really know the answer to that question. It's a pretty important outstanding question about how planets form and how they spin up in their original state. Venus also has its axis pointing straight up and down. You know how Earth were on a tilt? And as we travel around the Sun, because we're on that tilt, that's why we have seasons, different temperatures and different climates in different parties of the year. Well, at Venus, that axis, that spin axis, is straight up and down. And so there's no seasons on Venus. In addition to not having seasons, the atmosphere on Venus is incredibly thick and dense. So you almost have no difference between day and night, as far as what it's like on the surface of the planet, other than the amount of lighting that's available. But even that's not much different. The atmosphere on Venus is about 96 1/2% carbon dioxide, which has set up what's sometimes called greenhouse gone wild on Venus, okay? And what that means is that that thick, dense carbon dioxide atmosphere is driving like a pressure cooker environment down on the surface. So the surface temperatures are about 860 degrees Farenheit. Let that sink in for just a second. That is hot enough to melt lead. It pretty much melts anything except for titanium. It's incredibly hot. It also has air pressures, about 92%, 92 times what we feel here on Earth. So imagine when you're about half a mile underwater, that weight of the column of water on top of you, that's what it feels like on the surface of Venus, what it would feel like. At the top of the atmosphere, there are hurricane force winds blowing around the planet about 250 miles per hour, 100 meters per second at the top of the clouds. We don't really understand what drives those winds. Why do they super rotate? Why do they rotate so fast? Remember, the planet, the surface of the planet is rotating really slowly. So those winds are moving about 60 times faster than the planet itself is rotating. Why? How do you do that? How do you describe, if you're into physics, how do you describe the momentum transfer that happens between the surface and the atmosphere when they're behaving and moving so differently? We don't really know the answer to that question. Down at the surface, as you go down near the surface, those winds that are racing at 250 miles per hour at the top are almost non-existent. Maybe two miles an hour, maybe. We don't really know. We don't have good data down low. But we know they're really low. There's not a lot of wind on the surface at all. And that surface down there is this carbon dioxide super critical fluid which doesn't really behave like water or like a liquid or a gas. But you can imagine things on the surface, it's more like being on the bottom of the ocean. The air would just move more or less like a very low moving current on the bottom of the ocean. To add to all of this fun and excitement at Venus, if being hot and high pressure wasn't enough, to get to the surface, you have to go through a 15-mile thick layer of sulfuric acid. That's always fun. So that sulfuric acid layer blocks most of the sunlight that arrives at Venus. So Venus is closer to the Sun than Earth, so it gets a lot of sunlight. But 90% of that sunlight gets absorbed as it passes through all of those clouds and this thick carbon dioxide atmosphere. So by the time you get down to the surface, only about 10% of the light gets through. This has been important when we're thinking about designing missions that will come back later because you can't use the Sun as your power source, right? Because there's just not enough Sun down there. It's not pitch dark. It's like being outside on a really cloudy, overcast day. You can see. I'll show you a picture later from the Viera [phonetic] spacecrafts from the Soviet Union, that they were able to see down on the surface. But it's pretty low lighting. So when we start thinking about Venus, again, they started out the same. They're almost the same size. They formed in the same part of the Solar System. Similar masses, presumably similar composition when they first started out in the early Solar System. And yet somehow Earth and Venus took very, very different paths in their evolution. Why? When did that happen? Why did it happen? These are the big questions. We don't know the answers to. We don't know. And we need to know. And the reason I would argue that we need to understand Venus better is because we are now in this really exciting era where we're discovering new planets around other stars every day. Exoplanets, planets around other stars. Just last week, I had to put the date on here because it's over 3,500, but it's probably more than that today. It changes every day. Every time I give this talk, I have to update my slide because it increases by another 500 or 1,000 planets. I mean, it's just insane how fast we're confirming, not just think we identify, but confirming these other planets around other stars. And as we're looking at all of these other planets out there around these stars, hundreds of those 3,500 planets, hundreds of them are in a size range that's similar to Earth and Venus and Mars. And that's just the ones we know about. There's smaller ones we haven't even been able to detect yet. But there's hundreds of them in this size range. And some of those, dozens of those, are in a range near enough to their star that could be in a habitable zone, that could be habitable by life as we think we know it. But if we don't know the difference, if we can't tell why Earth evolved the way it did and Venus evolved the way it did, how would we ever be able to tell the difference between Earth at any point along its evolutionary path, what did it look like 4 billion years ago, 3 billion years? What's it going to look like in the future? If we can't tell the difference between that and Venus and what it looked like 4 billion years ago and now and into the future, how are we going to decide, as we look at all of these vast exoplanets, how are we going to decide where we want to go and where we really want to look for another Earth-like planet? It's my bet that most of those planets we're finding are going to be more like Venus than more like the Earth. So we really need to understand why Venus turned out the way it did. So a very brief description of expiration of Venus, Stephanie said there has been some early exploration of Venus, she mentioned the early Mariner, which was great. The Mariner mission that flew by Venus that was the first mission to go by Venus, I didn't include that here because it was pretty minimal as far as the results we got back. But we did get an important result back from Mariner, which was that we knew the surface was not going to be a lovely place for humans to inhabit. We learned that it was going to be very, very hot. Up until that time, there was a lot of science fiction that said it was going to be very tropical, and there were all these Venusians down there, you know, having a great day in the shade. But then all of that went out the window with Mariner. But Venus really was a popular destination for very early exploration in space. Partly because Venus is right next door, it's easy to get to, only takes a few months, four or five months to get there in a spacecraft. So the Soviet Union really had a lot of success at Venus. And the main reason they had a lot of success is that they had a brute force way of doing things. They would build two spacecraft, they'll build two landers, and they'd throw them at Venus. And if they didn't work, they'd learn from that experience and they'd throw two more and then they'd throw two more. Every time, they'd launch two and send them out there and see what happened. And we learned a lot. We learned there's really high pressure, we learned it was really hot, we learned it was corrosive, and they learned they had to beef these things up in order to survive and make it to the surface. But between 1961 and 1983, they sent a whole slew of these things to Venus. And about four or five of them did really well and lasted for at least an hour on the surface. One of them lasted almost two hours. And we were able to get some really basic information about what the rocks were made of in the big planes where the landers landed. In 1978, the United States decided to join the game and try Venus. We first sent this pioneer mission included two parts. The first part was an orbiter. And the orbiter went into orbit at Venus in 1978 and it lasted until 1992, taking measurements mainly of composition in the upper atmosphere. Also, along with that mission, we dropped off four probes into the Venus atmosphere. One was a bigger probe, the Large Probe, and it carried instrumentation that let us try to measure some of the composition as we descended down through the clouds. There were also three smaller probes that went down that didn't have the same kind of instrumentation. They mainly were getting after temperature and pressure as they went down through the atmosphere to the surface. The Large Probe was a good mission, but it had some issues. I'll talk a little bit more about that in a minute. In 1985, the Soviet Union decided to go back to Venus. They partnered with the Europeans to send another one of their landers and a couple of balloons. The balloons lasted for a couple of days in the atmosphere, floating in the cloud layer, in that sulfuric acid cloud layer, which you can imagine, remember, sulfuric acid, so it's corrosive, so it's going to pretty quickly eat through your balloon material, plus when the balloon goes around on the back side, it's kind of hard for it to communicate back to Earth. So they lost the balloons after a couple days. But again, some good information about the cloud layer. In 1989, the United States sent the Magellan mission. This was a great mission, carried a radar system that was able to see through the clouds and map the whole surface of Venus. It's a great map. It's the only map we have of Venus, so we are very glad to have it. But I'll remind you, you know, we get so spoiled in this modern age, we look at the kind of images we get from Mars with, you know, resolutions that are, you know, like this. You can see individual pebbles and rocks on the surface. The Magellan images are the type of resolution similar to, if you go back and look at Viking images of Mars from the 1970s, that's what we have for Venus, okay? So it's very hard to answer some of the kinds of questions that we now address on Mars about actual geologic processes and geophysics. It's hard to answer those questions with these old data. So they're good. We're glad to have them. But we certainly need more new data there. More recently, the Europeans have been there, been to Venus, with Venus Express. They had a mission that lasted about eight years, over eight years, that mapped and looked at chemistry and dynamics in the cloud layers and in the upper atmosphere. And then as Stephanie mentioned, right now is a Japanese mission called Akatsuki. And it was launched in 2010. It missed orbit the first time. Finally got into orbit in 2015. It's a great success story of perseverance. They used their little tiny thruster engines in order to get into orbit. And so they're there. And again, making pictures and taking data of the upper atmosphere, looking at cloud dynamics. But what I want to draw your attention to here is to think about the last time the United States went to Venus was 1990ish. Again, with instrumentation that was probably 1970s technology. So that's where we are with that with the U.S. The last time anyone went into the atmosphere or down to the surface of Venus was in 1985, again, with old technology and the kinds of questions that we need to answer. We just don't have the data available for Venus. But what did we learn? So we learned a lot. We did get some answers, but we also got a lot more new questions. But I'll tell you some of the things we did learn. One thing we learned, of course, is that the surface of Venus appears to be very volcanic. Most of the surface is covered in volcanic flows and volcanoes and the volcanoes on Venus look more or less similar to the types of things we have on Earth. They look like volcanoes that we understand with lava rocks that come out, just like they do on Earth. But the main difference is, this is Venus here on the left, and this is the Magellan figure showing topography. So the blues are not water. They're actually very low-lying areas. And the pinks and whites up here are the high levels and the mountains and things on Venus. But what we see on Venus is that there's no evidence at all for plate tectonics like we have on Earth. We have plate tectonics. Our plates are all moving around, subducting under each other, riding over each other. And that's where most of our volcanism happens on Earth, is at those plate boundaries. We don't see those plates on Venus. We see volcanoes, so they must be popping up somehow. But what we don't know is why Venus doesn't have plate tectonics and Earth does. They should both be hot on their interior. They both need to be losing heat in some way. This is plate movements and the volcanism along the plates, that's how we lose our heat on Earth. How is Venus losing its heat? It should still be hot. Is it still volcanically active? And we'll come back to that one in a minute. What does the surface look like? We have pictures from four landing sites from over 30 years ago. This is what we have for the surface. This is what we know. We've got a couple of these. It looks like dried up old lava. It looks like a basaltic flow. If you went out to Hawaii and walked around lava flows, they kind of look like that. So that's what we know of those four landing sites. But because of that thick cloud layer, again, the only way we can see the surface remotely from orbiter is with radar. And so that's all we have. And that radar sometimes can be a little difficult to interpret with our eyes that are used to seeing things at more optical wavelengths. Radar wavelengths are a little more complicated. Other things we've learned about the surface. Again, a lot of questions. First, again, about 80% of the surface appears to be covered in these lava flows. All right, I'm good so far. There appears to be lava flow. That makes sense to me. From what the Soviet landers told us with their chemistry, we can infer, we can guess that most of those lava flows are something we call basalt, which is the most primary kind of volcanic rock. It's the kind of volcanic rock you find in Hawaii. It's very primitive. It's the kind of rock you find at the mid ocean ridges on Earth. So that's not terribly surprising. That's good. But we found fewer than a thousand impact craters on Venus. That's not very many. Look at the surface of Mars and Mercury and the Moon. Thousands, hundreds of thousands of craters of all sizes. You go to Venus, there's less than a thousand craters that can be identified. Yes, it has a dense atmosphere. Yes, the smaller asteroids are going to be destroyed. But what about the big ones? Where's the big ones? There's not even any big basins like you see on Mercury and the Moon and Mars. They're not there. We haven't seen them. We don't know. They all appear fresh. There's not very many of them. And so the way this has been interpreted is number one, the surface is pretty young, okay? The other thing is those thousand craters that have been studied statistically appear to be randomly distributed on the whole surface of the planet, which tells us that the whole surface is more or less the same age. That's a little weird. I'm not sure how you do that either. So the question is, or what the assumption has been, that this surface is about 500 million years old, plus or minus several hundred million years old, but still relatively young. And it's all about the same age. So one thing that's been proposed is well, maybe you need to constantly be resurfacing that surface with volcanoes, right? With the volcanic lava flows. And you can do that either through constant volcanism, which means the surface was very, very young or just turned off 500 million years ago. Or you can do it through periodic overturning events perhaps, right? The interior gets really hot and you've got this lid, this stagnant lid trapping all of that heat, and then maybe every 500 million or a billion years, that heat builds up and it just turns over and you get this rapid resurfacing of the surface. But we don't really have enough information to answer that question. We also had these unique geologic features that we see. They're higher than most of the rest of the topography. They're higher than the basaltic plains. And we call them tessera. Tessera is a Latin word, I believe, that pretty much describes this kind of aparque-like fabric, right, this crisscrossing tectonic fabric that we see in this region. And these tessera, we don't really have any known analog in the Solar System. We haven't really seen this anyplace else. We don't know where and how you can get these perpendicular faults that are disrupting and changing the morphology here. We don't know how you can do that. We also are even further intrigued by these things, these tessera regions. Again, they're higher than everything else. If you look at the stratigraphy, which is looking at the ages of things, we can look and we can see that some of the lava flows look like they've lapped up against the edges, which tells us that the tessera are older than the lava flows that surround them. So these units might be older than the basaltic plains. They also might have a slightly different composition. They might not be basalt. We see from Venus Express, I said the only way you can see the surface is with radar, and nobody flinched. Venus Express carried an infrared camera that had one channel at the one micron region that could see and penetrate through the clouds all the way to the surface. And so in that channel, they can measure reflectivity in the infrared. And what we see over here, this is a big region called alpha, Alpha Regio, Alpha Tessera. And it's a different color in the reflectivity because it has a higher reflectivity than the surrounding basaltic rocks. So on Earth, rocks that have higher reflectivity are usually things that have more silica in them or more evolved rocks. And so those types of rocks we typically associate with the volcanoes that erupt along our plate boundaries. And those volcanoes require water in order to get those compositions. So the implication here is that maybe, number one, these tessera could be older than the plains. They may record or preserve some era of history before the current era that we know now. And they may have involved water in their formation. But we don't know the answer to that. We need to go down there and measure the chemistry of those rocks to really understand what they are. So now I'm going to step back off of the surface. Let's think about, in general, about Venus's origin and how it got to where it is today. So this is a very simple diagram of the planets in our Solar System. We got our Mercuries, Plutos, Mars and stuff, these are things that are basically rocky things that don't have any atmosphere, or very, very little atmosphere. Then you've got your Venus and your Earth, which are mainly rocky planets with substantial atmospheres, but not huge. You've got your Neptunes and your Uranuses. These are the icy giant. And then you've got your Jupiter and Saturn, the big gas giants, that these have solid cores and some rocky material maybe in the center. But they're mostly gas. So Venus and Earth, I said they're formed in the same part of the Solar System. What we've assumed is that they formed from the same types of material and kind of started out in the same way. But the question is, is that a good assumption? Did they start out with the same kind of genetic make-up when they started? Well, the way we measure that on Earth and Mars and Jupiter and other planets in our Solar System is by looking at particular gases that you can find in the atmosphere, the noble gases. And the noble gases are inert. Or what that means is that they don't like to combine with any other gases. They don't want to play nice. They don't want to get involved in any chemical reactions. These are gases like the helium, neon, argon, krypton and xenon. So what do we know for Venus? I've got a chart over here, and we've got Mars on the bottom, Earth in the middle, Venus right here. These first two green points are Venus, the data that we know. And what we see is that Venus and Earth and Mars all kind of have the same trend. They have the same shape in their abundance of those key gases. But Earth has more than Mars, more abundance, and Venus has more than Earth. That's okay. It's just more, but it's more or less the same type of arrangement. So with neon and argon, we say, okay, we're in pretty good shape saying that Earth and Venus form from the same materials, maybe more of something or another at Venus, but more or less the same. But then we get to krypton and this story starts to fall apart. The neon and argon were measured pretty well by Pioneer Venus. Krypton was also measured by Pioneer Venus and by Venera, one of the Soviet spacecraft. And what we have is kind of hard to see here, but you can see a giant error bar there for the green. And what you can see, those two measurements, the Pioneer Venus and the Venera were 15, a factor of 15 different from each other. So we don't really know how much krypton is there. And at one end of this error bar, we're pretty good with keeping with our story that Venus and Earth are the same. But at the other end of that error bar, we've got to start over and start rewriting how you make planets. We don't know how you do that. How do you end up with that much less krypton when you have these other abundances of neon and argon? We don't know. So we really need a better measurement of the krypton if we want to answer this story. And then you come out to the xenon, and nobody has ever measured xenon at Venus. It's very difficult to measure. It's present in really, really small quantities, so it's hard, hard to get your hands on what it is. But these gases are like little molecular fossils in the atmosphere that allow us to look back. If we can measure these, we can look back and see what Venus was like 4 billion years ago. So if we can make these measurements and get these abundances of the krypton and the xenon, we'll be able to look back and see into the history and understand what Venus was like when it first formed. Another major question, I think I alluded to this at the beginning, is that we think Venus was an ocean world when it started out. It used to have vast oceans. We know that or we think we know that based on a measurement from Pioneer Venus that measured the deuterium to the hydrogen. Now, deuterium is just another word for hydrogen that has an extra neutron in it, okay? So it's a little heavier than the regular hydrogen, which makes it a little less easy for the deuterium to escape from the atmosphere. So the hydrogen escapes a little more easily than the deuterium. If we look at both deuterium and hydrogen and the relative amounts of them there, we can see about how much of that hydrogen has escaped over time. And by understanding that, we can look back and infer how much water must have been present in the past. If we know that number well enough, we can also start fitting our models to understand when that water disappeared and how that water disappeared over the 4 billion year timeframe. So we're pretty sure there was water there 4 billion years ago. We're pretty sure there was a lot of it there. We don't know when it was lost. Originally, we all assumed it was probably lost very early on 4 billion years ago. But just recently, a paper came out, maybe a year ago now, that said maybe, according to these they will modeling studies, there was actually water present on Venus, liquid water, on Venus a billion years ago, one billion years ago. That's pretty recent in geologic time. It would also mean that if there was really water on Venus until a billion years ago, water would have been much more persistent and long-lived on Venus than it was on Mars. Are we looking in the wrong place? Just a thought. Just a thought. Just saying. All right, but what do we need to know? How can we better understand how much water was there and what happened to that water? Well, the amount of water that's present there is still controversial. As I said, Pioneer Venus did make a measurement. However, Pioneer Venus was a great mission. Loved it. It gave us a great insight. Made wonderful measurements of the composition of the atmosphere as it descended through the atmosphere. And then as it was going through that wonderful sulfuric acid cloud layer, a sulfuric acid droplet got sucked into the mass spectrometer and clogged the inlet. So we got a measurement of that one sulfuric acid droplet, which is great. But we missed out on a lot of other stuff because we didn't get anything else below that, which is too bad because there's a lot of information we need to know. But even that one measurement on that one droplet isn't good enough to tell us what we need to know. In part, we have other measurements from Venus Express that took measurements of the D to H, the deuterium to hydrogen, above the clouds. And those measurements show a D to H ratio that's as much as three times more than what we measured on Pioneer Venus. So now we're throwing our hands up, I don't really know how much water was there, I don't really know what that D to H ratio is in the deepest part of the atmosphere. This is a chart over here that just says D to H for a bunch of different places in our Solar System. And the numbers we have for Venus are basically off the chart. But we don't really know where Venus lies. And that's a question we need to answer if we want to understand its water history. Thinking about the atmosphere, I mentioned that the clouds at the top are moving at 250 miles per hour, hurricane force winds. What drives that? How does that happen? We can watch it. We can observe it. But we can't model it. We are not doing a very good job of modeling it. We don't really understand why they move so fast. And we don't understand how the Sun interacts with the molecules that are in the clouds, the types of chemical reactions that happen in the cloud layer or within the atmosphere and how the Sun plays a role in that, we don't fully understand. There's also half of the UV, the ultraviolet light, that hits the Venus atmosphere, that gets absorbed in the Venus atmosphere, that may have something to do with this whole story of dynamics. You can see this image over here, this dark area, this is from Venus Express. Again, ultraviolet image. And you can see dark areas and light areas. This ultraviolet light is being absorbed, but we don't know what that is. We don't know what chemical species is doing that. If we knew that, it might help us answer some of these questions about the chemical processes going on in Venus's atmosphere. But we don't know. Deeper down in the atmosphere, we know even less. We've had Venus Express, we've had Akatsuki, we've had Pioneer Venus orbiter looking at the top of the clouds. But getting down below the clouds is really challenging. It's hard. And so we don't know a whole lot. This chart on the left basically is hard to read, I know. It's very tiny. But this says Venus Express and Akatsuki, which were orbiters up high looking at the atmosphere, here I've got the little Vega balloon making its little rounds around the planet for two days looking in the cloud layer. The Pioneer Venus probes that were able to probe part of the atmosphere, but then sucked in an acid droplet and stopped working. And then we have landers down in the surface. But this little cloudy area down here that's hard to see, this part is really virtually unexplored. We don't really know what's going on in that part of the atmosphere. I've got Earth over here for scale, and again, hard to see, but this is an airplane, okay? That basically says the comparison here is this is 75% of Venus's atmospheric air mass below that altitude. 75% of Earth's atmospheric air mass is below the altitude where aircraft fly. So just imagine if we didn't know anything about Earth's atmosphere below the height where aircraft fly. That's a pretty big important part of our atmosphere that we don't understand on Venus. The chart in the middle, these are all different chemical species' name. You don't have to memorize them or know them. But this is OCS is carbonyl sulfide. CO is carbon monoxide. Most of us are familiar with that. H2O is water. SO2 is sulfur dioxide. What's showing here are the amounts that we think are present in the atmosphere of Venus down below about 30 kilometers above the surface. But all of these little wires on this diagram are guesses based on models and assumptions. We don't know. We're guessing what we think is down there. And we're guessing about what those chemical processes are that are going on in the deep atmosphere. We don't really know. This is another attempt at trying to understand how we came up with that wiring diagram on the other page. Again, you do not need to understand this chart. This is the Venus sulfur cycle. And one person's idea of how they think, all of the different sulfur reactions are happening in the atmosphere. It's a very complicated process. There's lots of these trace gases that are only present in very small amounts. And we don't really know how they interact with each other, and we don't know how they interact with the rocks on the surface. Are they chemically weathering the rocks? Are they pulling some of the chemicals out of the minerals that are present at the surface and putting those, exchanging them with the atmosphere? We don't know. We do know there's a lot of sulfur in Venus's atmosphere. It drives all of those big sulfuric acid clouds. But where does all that sulfur come from? Is there a supply of sulfur today? Can you supply it just by weathering the rocks? Or do you need some other active supply of sulfur into the atmosphere? We come back to is Venus volcanically active? I said there's all of these unknown questions about how does Venus lose its heat? Does it still have active volcanoes that are putting material out onto the surface and into the atmosphere? And if it is, could we tell? I will tell you we've been going to Venus now, you saw, since the early 1970s, and we have yet to see a smoking gun. We've got hints, and I'm going to show you those in just a second, but we haven't seen anything that we can say yes, gosh darn it, Venus is volcanically active, it's erupting right now today. We don't know. But again, should be hot inside, should be losing its heat, should be volcanically active. So let's talk about some of the evidence, circumstantial evidence that we have that maybe Venus is volcanically active. This chart over here starts with a peak here. This is when Pioneer Venus orbiter arrived at Venus in 1978. And it started taking measurements of sulfur dioxide above the Venus clouds. And then you saw a spike, and then it dropped off exponentially over the lifetime of Pioneer Venus. And then we have a big gap because nobody was at Venus. And then Venus Express showed up and they saw another big spike in sulfur dioxide and another decay, and maybe another little spike, maybe, and then more decay. So these spikes, what causes spikes in sulfur dioxide at the top of the atmosphere? I mean, these are at 70 kilometers 43 miles up. That's pretty darn high. Well, on Earth, what causes pulses in sulfur dioxide at the cloud tops is volcanoes. Volcanoes emit a lot of sulfur dioxide. Notable examples are Pinatubo shown here on the right. This is not the big one. This is not the big eruption. This was the day before the big eruption. The actual big eruption, they were having a typhoon, so there's not very many good pictures of that. And people were running away. Not in pictures. But Pinatubo put an enormous amount of sulfur dioxide into the atmosphere, and that sulfur converted into sulfuric acid aerosols, and it actually changed the weather regionally for a period of about two or three years, okay? Cooled off the surface. Warmed the stratosphere, cooled the surface. So is this happening on Venus? Well, on Earth, the largest plumes, the largest volcanoes, the plumes that rise in the atmosphere go to about 20 to 25 miles in the atmosphere. And as Stephanie said, this was an area, this was how I got into Venus because I love volcanoes. That's how I started. That's what I was studying. And all of a sudden, I saw this on Venus and I thought, how cool, are there really active volcanoes on Venus? So I started modeling volcanic plumes on Venus. And what I found is that it is extremely difficult to have a convecting buoyant plume in Venus's atmosphere because it's so hot, the atmosphere is so hot and so dense, it's very hard to do that. I'm not saying it's impossible, but it's very difficult to do on Venus, to drive sulfur dioxide all the way to the top of the clouds. So where we are left with, okay, maybe it's volcanoes, maybe, but there are other hypotheses. You could actually have just random periodic overturn events in the cloud layer. We know that beneath the sulfuric acid, just below the clouds, there is kind of a reservoir of sulfur dioxide there. That's where it accumulates. And so if there were just a random overturn, you would get a little pulse of sulfur coming up to the top. You could have even had a meteorite disturb it and cause that overturn. So there's other hypotheses. Volcanism isn't the only answer, although very tempting to want to go that route. Other possible evidence of active volcanoes on Venus, I mentioned that the Venus Express instrument had an infrared camera that had one channel that could see all the way to the surface and measure the reflectivity of the surface, the emissivity. And they've seen some anomalies. These are some high emissivities, so low reflectivity over a volcano in southern Venus hemisphere that they associate with or have interpreted it to be associated with young volcanics, unweathered volcanics, which doesn't mean yesterday young, it means thousands of years young. But basically unweathered material that could be present at a currently active volcano. More recently, there was a study published where they saw one of these emissivity anomalies not there, there it is, now it's not there. Is this a thermal signal from an actual active lava flow on the surface? Maybe. It is associated with a volcano, but then a lot of things on the surface of Venus are associated with volcanoes. And there's a lot of modeling involved and a lot of things that have to happen in order to pull out this little tiny signal. So there's still a lot of debate. Is this really, is this anomaly real or is it not real, is it just a variability in the clouds or what is it? But it's tempting, it's really tempting to say we've seen active volcanism, but as of yet, we haven't been able to say here is a place where there wasn't a lava flow, you know, back when Magellan flew, and here today is a place where there is a new lava flow that wasn't there before. Haven't seen it yet. All right, so I have hopefully now convinced you that Venus is a fascinating place with lots of things we need to know, and that yes, there have been some good missions to Venus, but we're still, we've got so many questions, and there's still so many things that we need to know, that need to be measured at Venus. So let me talk a little bit about NASA's programs and NASA's plans and how we would go about, we here in the U.S., would go about trying to get a mission back to Venus, which is near and dear to my heart. I've been working on this now for about 10 years trying to get some way back to Venus. NASA has a discovery program. This is a program, it's a competed program for principal investigator-led missions, meaning they're led by a scientist. These missions are typically about $500 million in cost. That's a small mission for NASA. Typically, the missions that you might know of that are in this class of mission include things like Dawn that went to, most recently it's been a series, finding some amazing things there, also went to Vesta. The GRAIL Mission, which mapped out gravity at the Moon. Messenger, which went to Mercury and had a great time there. Mars Pathfinder, the first rover on Mars. Kepler, which is now discovering all of these fantastic exoplanets. And InSight, which is yet to launch, is going to be a Mars mission, going to land on the surface of Mars. And I think it launches next year in 2018. So NASA holds a competition for these every few years, for this class of mission. The last round of this competition took place in 2015. And in that round of competition, there were 28 incredible concepts that went into NASA for review. They could be about anything in the Solar System. And of those 28 concepts, 5 were down selected for a 9-month study. They got a little additional money, not a lot. A little bit from NASA to go back and sharpen their pencils and do a little better job of defining their mission concepts. Of those five, two of them were to go to Venus. One was proposed by my good colleague out at Jet Propulsion Laboratory. And what she was proposing to do was send a new radar to Venus, which is sorely needed. A new radar mission that would remap the surface in much greater detail and provide topography that would be actually useful for studying geologic processes. To complement that, the mission that I led that Stephanie mentioned was called DAVINCI, the Deep Atmosphere Venus Investigation of Noble Gases, Chemistry and Imaging. I've worked on that, practiced it many times. So the two missions were very complementary. DAVINCI is very focused on trying to get back into the atmosphere of Venus and make some measurements inside the atmosphere, those composition measurements that are so sorely needed. In addition to those two Venus missions, there were three asteroid missions that got additional funding for study. And then at the end of the day, no Venus missions were selected. Two asteroid missions were selected, one called Lucy, which is going to go visit five asteroids that are in Jupiter's orbit called trojan asteroids, and a mission called Psyche, which is also very cool. It's going to go measure a particular asteroid named Psyche that we think is made all out of iron. The PI, the principal investigator, believes that this is an asteroid that had all of its crust blown off and left just the core. So it's the opportunity to see potentially a planetary core up close and personal. So both very cool missions. Not, you know, don't want to say anything bad about them. But we still need to get back to Venus. So this is just a quick nutshell idea of what the DAVINCI mission would be if it gets to be reproposed again. It's a probe, looks something like that. It's a ball, it's a sphere about this big, containing a bunch of instruments that would focus on measuring of course those noble gases, making sure we nailed down the krypton and the xenon, trying to get at the atmospheric composition in that deepest part of the atmosphere below the clouds, understanding how the atmosphere interacts with the rocks on the surface and what kinds of processes and chemical reactions are going on there in this part of the region that's unexplored, trying again to understand the interaction with the surface. And then we would take pictures, of course. Because if you're going to go down, you've got to take pictures. And we would go over that unique terrain, that tessera terrain that we don't understand, we don't know as potential continents, and try and get some pictures that our eyeballs can relate to and understand what's going on there. So that's DAVINCI, not selected yet, but don't give up hope because there's another program at NASA called New Frontiers. New Frontiers funds missions that are about twice as much in cost. So these are the medium class missions for planetary at NASA. These are about a billion dollars. This program was established in 2003. And so far, there have been three missions in the New Frontier's category. You've probably heard of them. New Horizons, which was out at Pluto in July of 2015. Incredible mission. Took some amazing pictures and got some great data of Pluto. It's now heading off to another Kuiper Belt object. Juno, which now in orbit on Jupiter, and OSIRIS-REx, which launched last September, is going to fly to an asteroid named Bennu. It's going to fly around it, orbit around the asteroid, and better understand the asteroid. And once it's mapped it out really good, it's going to dip down, take a sample and bring that sample back to Earth so that we can study it for decades to come. So it's a very exciting mission. NASA likes to try to compete this category, probably about twice every decade. And so there's a current competition going on right now. It just closed at the end of April. My Intel tells me that we think there are about 13 proposals submitted. That's hearsay. There's no official accounting yet. But I think there are about 13 proposed. And of those, again, my Intel, it's not confirmed, so off-the-record, 3 Venus concepts out of those 13, I believe. Again, I can't talk about the other two that I don't know anything about. But I do know about one called Vicky, which is actually mine. Again, I'm leading this one as well as principal investigator. And, of course, since we didn't win in discovery, we took our DAVINCI concept and said, what can we do to add to this concept and really, you know, make it a billion dollar class mission? And so what we did was we took our descent probe and we gave it some stabilizers so that it could land on the surface. So in addition to doing all the things that we were going to do on DAVINCI which is measure all of those gases and focus on all of that science that could be done why you're descending through the atmosphere, we would then land on the surface. Again, landing in one of these really interesting tessera environments to see if we could measure the chemistry and the minerals and morphology, which is just a fancy word for trying to understand how geology has shaped the surface. Look very closely at these on the surface of Venus. So that's what the Vicky mission is, it's Venus and [inaudible] composition investigation. So that one is in competition. We should know in between October and December will be an announcement from NASA headquarters indicating which of those 13 or so missions or down selected for additional study. We've got our fingers crossed that at least one of those three Venus missions will get selected. You know, I've invested a lot in mine, and I'm very partial to my mission, but I'm also more partial to Venus. And so what I really want to see is a mission to Venus. All of the scientists that have proposed the Venus missions are excellent. All the missions are good. We just have to get one one of these days. We will. Outside of NASA, what's thinking about Venus? Who wants to go back to Venus? Well, Europeans have had this very successful Venus Express mission. And so they're already going back to the drawing table. They said, well, with Venus Express, we focused a lot on the atmosphere and understanding the chemistry and dynamics of the atmosphere. What's next? And so the Europeans are also very interested in an orbiting mission with a radar, carrying a radar that can do higher resolution imaging and get topography. Their mission is called ENVISION, and that is also currently under competition in their M class category, which is their medium class category, which is a little bigger than our medium class. But it's a good size mission. But it's under competition. We don't know where that stands right now. And Russia is also currently thinking about a potential new mission to Venus, a new Venera mission. It's called Venera D. And do not ask me to pronounce the word that begins with D because I cannot do it. But it means long lived, which means hopefully will last longer than one hour on the surface. It should last maybe five hours on the surface. How exciting. And there's no commitment from the Russian government to fly this mission. But the Russian Space Agency and NASA are working together right now to define what the science is that this mission would do. So we are working on a joint science definition team with the Russians and trying to map out if we ever could get support from all the relevant governments, could we fly another mission led by the Russians? This mission that they're thinking about would include an orbiter, a sub orbiter, a lander, and maybe some aerial platforms, which aerial platforms could mean a balloon or an airplane or something flying in the cloud layer. So it's a pretty aggressive plan right now. And at this point, as I said, no funding or any dollars really associated with it. But the scientific community, there's no lack of interest from the scientific community. It's trying to get the agencies and the governments to put some money behind it and make it happen. So with that, I think I'm going to wrap this up a little bit. The key things I really want you to walk away with today, number one, Venus is very similar to Earth. It was similar to Earth. They started out, we think, very similar. But somewhere along the way, something happened. Somewhere they diverged and they became very different in their climates and in their surfaces and in their-- in so many different ways. We don't understand when or why that happened, but we need to. We need to if we want to understand how these rocky planets with atmospheres, how they form, how they evolve over time. How did that work even in our own Solar System with our little suite of Venus, Earth and Mars? We've got three N members there. We're missing one. We know Mars pretty well. We don't know Venus. We need to do that. If we're going to understand and interpret the exoplanets that we're discovering, we're missing some important information on Venus. Another thing to walk away with is right now, as of today, there are no planned Venus missions of any kind by any country right now. Lots of things in the works, but there have been lots of things in the works for many, many years. We did a count the other day within NASA competed programs. Venus is 26 and 0, 26 proposals and 0 wins. So, you know, new love for Venus so we can get back there. So my last pitch to you is that, for me, what I think we really need to do to get back to Venus is really get back into Venus's atmosphere. The missions that have been to Venus's atmosphere, the Veneras, the Pioneer Venus, Large Probe, they got us started, but they really left us with more questions than answers. We've had, since 1978, I think I wrote it down here so I wouldn't forget, six orbital missions, six orbital missions. It's time to get back into Venus's atmosphere, make those in situ measurements right there in place in the atmosphere and see what we can learn. Not just about Venus, but about all of the other planets out there that are waiting to be discovered. So with that, thank you. [ Applause ] And I apologize for going a little long, but I will definitely stand here and answer questions for as long as you want to stand and ask questions. >> I think we have two options with our Venus exploration. One is somebody start a petition on change.org, get enough signatures, maybe someone will listen. The other is private funding. All the billionaires that are going to space. But questions, there may be lots of questions, but there are no answers, right? >> Well, that's not true. That's not no answers. It's interesting you mentioned the private funding because there's been a lot of interest in sending, you know, through private funding, sending people to Mars. There's not really-- we can't really survive at Mars any better than we can survive at Venus right now today honestly as humans. And there have actually been some interesting ideas for sending humans to Venus just on a swing-by trip, to swing by Venus and come back, you know, kind of a geo tours there, go out there and experience it and come back. But if you want to think about ways to get humans out into the interstellar or InterSolar environment, the interplanetary environment for an extending period of time, you know, it's a possibility. We might take some pictures along the way. Just saying. Over here, yeah? >> Can you talk about the dynamics of the first Russian probe that landed? You talked about one hour. And I assume they had to go through some orbiter to send those pictures. If they missed that shot through sulfuric acid atmosphere in storms and everything, it probably wouldn't get back around to being able to do their shot. Can you talk about what happened and how they did that? >> The question here is about the dynamics of those early Soviet landers and how they were able to communicate their data back. Someone can correct me, but going off the top of my brain, my recollection is those were direct to Earth communication, as was the Pioneer Venus large procedure. The Pioneer Venus probes were direct to Earth. They did not communicate through a satellite. I believe this communicated directly back to Earth. Very low bandwidth. And you thought your dial-up modem was slow. It was very limited. But that's my recollection off the top of my head. That is a very challenging thing to do. It is something that through my mission design efforts we've looked at a lot at how you can do that with a spacecraft and have the communication. One thing you can do is go on a fly-by trajectory as opposed to an orbit. So that gives you an extended period of communication time as your lander or your probe falls to the atmosphere, and then you can continue communicating for that hour or two or three on the surface. >> In the [inaudible] you said I think five hours is where we're at now technology-wise? >> That's where we're at now technology-wise, as far as cooling. I didn't get into a lot of the mission design stuff. I'm happy to answer those kind of questions too. Most of the thermal control, as we're talking about the lifetimes of these landers on the surface, a lifetime of five hours is probably limited by how cool you can keep your lander inside at 850 degrees outside. It's hard to keep it cool on the inside. And with power limitations, you can't continue to power a powered cooling system. So most of the early missions, or all of the early missions and everything I know of that's been proposed to land on the surface, would use a passive cooling, which is usually like a face change material that would go from a solid to a liquid. And by doing that, it keeps the inside of your pressure vessel at a constant temperature, much like ice cubes keep your glass of water at the same temperature. And so but when all of that face change material is melted, it's gone. So really the limitation there for five hours is how much of that face change material can you bring with you? Questions? I'll go here next. Yeah? >> My daughter-in-law is a planetary geologist whose Ph.D. projects go on the march. She's now living in Luxembourg, and on our weekend Skype, she said there's a flood of private money coming into VSA in Luxembourg in particular for asteroid mining [inaudible] purposes. So what is the role of government versus private enterprise [inaudible]? >> So the question here is about private versus public funding in things like asteroid mining or any kind of resource or resource mining. Yeah, well, on something like my project, like the DAVINCI, these are publicly-funded through NASA without any private funding. Although that's maybe not totally fair because we do partner with industry pretty heavily. For example, the DAVINCI mission was partnering with Lockheed Martin, and they would bring some of their internal resources to bear on that, but not like a huge crowdsourced funding. I can't really speak to other types of publicly-funded things and where you draw the line between NASA. That's kind of out of my, not only my area of interest in experience, but also out of my authority to speak on. So I apologize for that. I can talk to you maybe a little more after if you're interested. There was another question right here, and then we'll move around. >> If the cooling is your issue, I suppose that's because the electronics maybe [inaudible] or whatever, is it possible to develop high pressure electronic like your ceramics or? >> This is a great question about how do we solve the thermal problem? Is it all just cooling, or can you also develop things that work in the high temperature environment? Great question. Yes, it could work. We actually-- NASA has a funded program right now called Hot Tech, which is specifically focused on trying to develop high temperature electronics, which is great. We already-- I know of already a seismometer that's been developed that could actually function on the surface of Venus for a month under high temperature conditions. The problem is we've got the high temperature electronics, the soldering and the electronics work, but we don't have memory systems, we don't have transmission systems, we don't have, you know, we don't have the data storage and the communication capacity to get the data off the surface. So there's still a lot of investment and work that needs to be done there. NASA is investing in that. There's others that are investing in it as well. A lot of universities are doing research in that area. And so my guess is that somewhere along the line, the two will meet in the middle. We'll have things that can survive to higher temperatures, and we'll find better ways to encapsulate things to keep them in the range of temperatures where they need to be. But it's a great question. It's something that is being worked on. It's not ready to fly today, but someday. I think there was another question over here. Yeah? [ Inaudible ] Whew. That's a great question. I'm not sure I know the answer. Okay, so the question is how deep is the Venus atmosphere, and how does that compare to Earth? So the cloud tops on Venus are at about 70 kilometers, so quickly in my mind, 40 miles ish, 35, 40 miles. It's pretty big compared to Earth's atmosphere. It's much bigger than Earth's atmosphere. And when you-- it's pretty dense even at higher altitudes than Earth. It's pretty stable in that density at the high altitudes. Because as they said, it gets up, the Sun coming in on it for hundreds and hundreds of days. So it's pretty stable. So then the second part of the question had to do with how far does the heat radiate out? That's a good question. And honestly, that's something I'll have to go back and research because I don't know the answer off the top of my head. I do know that spacecraft that are in orbit a couple hundred kilometers above the surface do have to deal with that radiation, absolutely, that comes off the planet. It's pretty bright. The clouds are really bright. There's a lot of radiation that comes back off the cloud tops. But I don't know the answer to that. Sorry. Another question? Right up here, and then I'll go back. No, go ahead. >> I just want to know, do you know already, you told us that it doesn't have any plates. >> Right. >> Now, if it doesn't have any plates, how are the volcanoes created? >> So great question. So the question is, if there's no plates on Venus, so it doesn't have plate tectonics, how are the volcanoes created? Well, this is a good question. On Earth, we do have volcanoes that are not on plate boundaries. We have a few, right? We know Hawaii is a great example of a volcano that's not on a plate boundary. It's actually what we call a hot spot volcano. It's fed directly from Earth's mantle. Magma comes straight up through the crust, right out onto the sea floor, and now Hawaii. >> But there should be a hole somewhere. >> Yes, there is a hole somewhere, definitely. And on Venus, there are holes. And the models that we have for Venus are what we call these heat pipe or hot spot volcanoes where the heat pipes are delivering the magma and the heat from the interior, right, from this mantle layer out to the surface. And so then there's a hole in the volcanoes, the lava comes out from the vent at the surface. But again, these are pretty limited. If you want to look at how you can get rid of heat from the inside of a planet, they're pretty inefficient to just lose it during these individual heat pipes as opposed to the kind of plate boundaries where we just unzip the whole Atlantic Ocean and lava comes out all along the whole thing. A question back here? >> I found it interesting that the planet spins a lot more slowly than its atmosphere. And I wonder if there's any evidence of, over time, the slowing of Venus, maybe because of gravitation, because maybe all of the gravity is at the Sun and we're faster because we have a lot of gravity on the other side, and whether that has any leverage for explaining maybe the newness of the surface, maybe building on the gentleman's question, if things inside are spinning either faster or slower over time, whether sort of the hot spots can form in that way, and whether if we can speed it up again, whether we can spin off the atmosphere and make it happen. >> Hmm, speed it up. Well, that might be challenging. >> A lot of energy. >> The question has to do with, you know, how fast the atmosphere is rotating relative to the surface, and all of the other tentacles that hang off of that as far as implications for, you know, how these volcanoes are forming and how planets in general feed volcanism through these kind of dynamics that go on inside the planet. And the answer to the first part of your question is that over the lifetime of the missions we've had at Venus, decades now with Magellan and Venus Express and Akatsuki, there have been a couple papers, and I'm going to try to remember the details, and I probably can't fish them out right here on the spot, but there was a potential that they saw some change in the rotation rate over time. But then there was another paper that came out that kind of discredited some of that because some of the assumptions weren't quite right. So again, it's kind of being debated whether or not its spin rate is changing over time. It's still kind of out there in the debate, but it's possible that it may be changing. And honestly, I don't remember if it's speeding up or slowing down. I'd have to go back and check that. But there's a possibility that it is changing. Whether or not you could spin up the planet again and try and blow off the atmosphere, there might be more effective ways to do that like introducing things that love to eat carbon dioxide and things like that. Yeah, there's a lot of different ideas out there for terra forming or trying to make it a more habitable place. Is there another question maybe down here? Yeah? >> Do you know anything about the size of the core and how it compares to Earth? >> Yeah, I think, again, I think from my recollection, the core of Venus is more or less the same size as Earth. So it's not that much different in size. What we don't know, though, is whether or not it's dynamically active. So at Earth, we have what's called a dynamo, where we know that there's convection going on, you know, outside of the core and in that deepest part of the interior. And that causes the magnetic field that we have here. Venus has no magnetic field, has no magnetic field. So this is yet opening another can of worms that I'll throw out there just for your consideration. At Mars, we use the fact that Mars doesn't have a magnetic field to explain why Mars has no atmosphere, that the solar wind has stripped off Mars's atmosphere, because it has no magnetic field. Well, what's happening at Venus? Venus has no magnetic field, and it's got more atmosphere than any, you know, than Earth and Mars combined. So how do you do that? So the core size I think is fairly similar to Earth. As I said, the densities, the masses of the two planets are relatively, you know, on scale with each other, right? Scaled. But there are other differences between them that we don't understand. Yeah? Let's go right here. >> So I really liked the talk and I found it super interesting, but I'm [inaudible] background, so I was wondering if you could recommend any resources or stuff that we could look up to sort of learn more about this topic. >> Absolutely. There is a great book, actually written by David Grinspoon, who used to work here at Library of Congress as astrobiology chair. And his book, oh, Venus Unveiled or Venus Revealed Very respectfully something like that is an excellent book for the lay person to really get engaged. He talks a lot about just kind of the mythology of Venus, and he also goes through-- it was written after the Magellan age, and so he talks a lot about what was learned through the Magellan data. It's a fascinating book. He's a great writer. I'm giving a little plug for David. >> You might want to spell his last name. >> Grinspoon, like grin, G-R-I-N, spoon, like spoon, S-P-O-O-N, Grinspoon, David. It's a great book. Let's go back here. Yes? [ Inaudible ] Great question. So the Vicky mission, which is the current one that's under competition, the question is, when would we potentially get back to Venus? At the earliest possible opportunity, if we win the current competition. The Vicky mission, if successful, would launch in 2025, okay? Yes? [ Inaudible ] Correct. So the question is, what kind of technology are we using on the proposed Vicky mission to survive this harsh environment near the surface? If you want to land and survive on the surface, how are you going to do that? So in all honesty, the technology required is not that fancy. We have a very, a pressure vessel, which is similar to the types of bathometers and stuff that we send under the ocean that can withstand great pressures on their exteriors. It's spherical in shape, which is a good shape for trying to fend off lots of great pressures. We do have some more modern ceiling technology than was used on the older ones that should help us keep from getting any kind of leaks. But then the kind of cooling technology is, as I've described, a passive system with a face change material, power sources or batteries, your typical kinds of batteries. We didn't talk about power too much in here, but nuclear power sources could be used on Venus, but they're not very efficient because nuclear power sources require you to dump and dissipate heat. And trying to dissipate heat into Venus's atmosphere, not very efficient. So in all honesty, the technology doesn't require that much advance. We have the technology available today to do that sort of thing. We are flying some very sensitive instrumentation. A lot of the instruments we'd like to carry to Venus, on either DAVINCI or Vicky, are the same types of instruments that are operating on the surface of Mars now, the same types of measurements that are making great discoveries every day about the Martian environment and the curiosity landing site. Those are the same instruments that we're proposing to carry on our mission. The biggest thing is trying to survive the entry loads. And so there are new technologies for trying to enter the Venus atmosphere to keep you protected from that atmosphere as you come in. And that's probably where the greatest technology development has been that allows us to come in at low angles on the top of the atmosphere to reduce the G loads on all of those sensitive instruments. Yeah, I think Pioneer Venus came in at like 300 G or something like that. I mean, it's outrageous, you know, G shock that it got coming into the top of the Venus atmosphere. And most of our instrument probably wouldn't like that very much. So we try and keep it much, much lower than that, yeah. More questions? Yeah. >> Did any of the past missions look for radioactivity? >> Yes. Did some of the past missions look for radioactivity? Yes, the Venera landers included a gamma ray detector, which detected naturally radiating materials, uranium, thorium and potassium. So we do have measurements of those naturally radioactive elements. And by looking at those, that was part of the data that went into trying to help us understand what kind of rocks are present on the surface of Venus. So that's exactly where those measurements came from. >> Maybe one more. >> I think I have one right here. >> Have you mentioned the other large economies in the world, like China, India, Japan or Germany who are funding missions? Or are they on silence? >> Other large economies that might possibly be thinking about missions to Venus, I mentioned the European Space Agency, which includes a consortium of France and Germany. They would be partnering. A mission of this size would require all of them to be partnering together. So they are thinking about it in that world. Russia is thinking about it, as I mentioned. ISRO, in India, the Indian Space Agency, is thinking about Venus. They've been thinking about Venus for quite a while. They've had some recent success at Mars. They've had some success at the Moon. And so they really are-- Venus is on their list once they get a couple more missions off of their kind of agenda. I think it's possible that Venus could rise up in India's interest. I have not heard of any interest that I know of of China thinking about Venus yet. Not that I know of. >> They probably want us to leave, so if you have a question, you can come on down while we close down here. Thank you all for coming. >> Thank you all so much for your interest. Thank you. [ Applause ] >> This has been a presentation of the Library of Congress. Visit us at loc.gov.