 The new features of the monthly webinars this year is we've been highlighting an activity to this month's topic this month. We're looking at a planet which has been an object of fascination for as long as people have looked up at the night sky. Mars has played a central role in much of the mythology associated with life beyond Earth and with all of the missions that have explored it in the last 50 years. And I'm going all the way back into the mariner, probes are actually more than 50. It remains an object of intense interest. And I think that Charone is incredibly interested in it. He's going to be sharing some things about the next upcoming mission. Well, one resource in particular allows you and that your visitors at your outreach events to explore the red planet in detail. That's Mars Trek. And we actually had a webinar from Brian Day back in 2016 about Mars Trek. And you can find a link to Mars Trek on this webinar's outreach resource page. And we'll also put that into the chat window here in a minute. Mars Trek allows you to select and look at layers of data from the various orbital missions. And so I just want to share my screen just ever so briefly here and kind of give you a little sense of what it does. And so hopefully we see Mars Trek up here. Hopefully that's what you're looking at. And I've got all these little chat windows kind of here or there and everywhere so I can actually see what I'm looking at. Now, one of the really cool things that you can do in Mars Trek is you can zoom in and you can look at all these different features on it. You can navigate around and really explore the surface of Mars. And so one of the things that is also really cool is that there's a set of layers. And if you click on here, there's a whole set of different layers that you can overlay on this and you can toggle the visibility and you can see some of the different features and from some of the different missions. And so here we've got, we can see where the Mars dichotomy is up here. We could go, we could turn that off and we could go to a more high resolution black and white imaging of it and you could zoom in and really get a sense of some of the things that you can see on here. You can also go to where the different landing sites are. There's a layer for where the proposed 2020, Mars Rover 2020 landing sites are. And so this is a really cool thing. Go back and check out the old webinar that Brian Day did for us. You can check this out and it's a really fun thing that you can use in your outreach or just for yourself too. I've had a great time playing around with it and refreshing my memory of how it works. So one more really great resource that we can use to explore Mars at our leisure. So one of the things also, we have a chat window in a Q&A window. Please make sure that you put any questions for Dr. Kedar in the Q&A window. That way we'll manage to keep track of your questions and be able to get to them at the end. And now for our featured program. Sharon Kedar obtained his BSC in Geophysics and Planetary Science from Tel Aviv University in 1985 and a PhD in Geophysics from Caltech's seismological laboratory in 1996. He also served as an NSF post-doctor at the USGS Volcano Hazards Program in the late 90s. He joined JPL's Geodynamics and Space Geodyssey Group in 2001 and JPL Sharon worked on a variety of earth science and applications projects as well as on mission concepts and instrument formulation in the earth, planetary and astrophysics area. He is the Insight Mission Seismic Experiment for Interior Structure Investigation Scientist. That's a mouthful. So we could just say he's a seismologist and that's, you know, he has a lot of passion for this and there's a lot that we can learn from seismology. So please welcome Sharon Kedar. Hi, Dave, can everybody see me or hear me? Yes, to both. Okay, so I'm gonna share my presentation and I'm going to put it in slideshow mode and then we'll get started. And thanks for the very nice introduction. So as you said, I am a seismologist. I'm actually one member of a very large science team. Those missions, this is what we call a discovery class mission, you may be aware of different programs in NASA. Discovery class is a fairly large mission that has several hundred people working on it. It's an international mission with contribution from the French Space Agency who are contributing the seismometer. The German Space Agency contributing a heat probe. We'll talk about those instruments in specific. The mission is managed out of JPO. And the PI, the principal investigator is Dr. Bruce Bannert, who couldn't be with us today. And I would have to say he's really the expert for this mission. I'm filling in for him. As you said, my background is in seismology. And as, so I can answer questions on many aspects of the mission, but perhaps not as well as Bruce on some of them. If I can't answer those questions, I'll make sure I can get back to you later on. Brian, a quick technical question for you. How do I see my own camera at the same time? That's a good question. Dave, is that up? Where's the command for that? It's not critical. We can just go on without it. But for some reason I can't see my own camera, my own face. So Dave, you're muted. Speaking of technical issues. Okay. In the right hand corner of your screen, you may see a kind of a series of small sort of squarish icons. And if you toggle between those, it'll give you slightly different views of the presentation. So one view just gives you, there's one view where there's nothing. There's one where you just kind of see a gallery view that might help turn that on or off. Okay. I don't want to waste everybody's time on this. So it's okay if we don't have it. It's okay. I know what I look like. So we'll go with that. All right. So the inside mission, which will basically place the first geophysical station on Mars will launch out of Vandenberg Air Force Base. This coming May 5th is when the launch window opens. And it will arrive on November 26th and operate for one full Marsy or roughly two Earth years. We'll talk a little bit about the launch later. As you know, the mission was supposed to launch in 2016 where there were some delays. We'll talk briefly about that. I'd be happy to answer questions about that. So let's talk a little bit about this mission. And what it's really all about. The mission is main objective is to study, well, obviously the interior of Mars, but really a little beyond that. So learn more about the rocky planet formation in general. And we know a lot, of course, about the Earth. And we know some about the moon, the lunar interior. In both cases, we know that from quakes, which are the equivalent source of similar to the analogy I'd like to give is ultrasound, sound waves, or in our case, elastic waves, that bounce off interior boundaries within the planetary body. But we really have only one data point, one good data point about rocky planet history information, which is Earth. And it'll be very informative to get another data point. We know something about the moon. The Apollo missions did have seismometers back in the 70s. The last one was turned off in September of 1977. But they were great instruments, but they were obviously limited by technology that was available at the time. And so our knowledge of the moon is not perfect. Also, the moon is very small. And we'll talk a little bit about why Mars in just a moment. So, they set a slide, I mean, they're really nice. It's the occasional corny figure. So, I hope you're not bothered by that, but I make a point. We think about it as a measurement going back in time. We really only started understanding what's inside the Earth at the turn of the 20th century when seismometers were developed. Before that, even in theory, what quakes were, people knew, of course, there were quakes, but what quakes really were and how the fact they emanate from an epicenter. This was not actually agreed upon fact at the turn of the 20th century. So, I would say we're basically doing zero with all order science on Mars. So, starting to just understand what is the thickness of the crust, what is the structure of the mantle, the size and density of the core, and what is the distribution of seismicity and the implication of all these questions to the history of Mars. And one particularly interesting thing about Mars is that it can help us understand the process of planetary differentiation in general on, we think, on other rocky planets. As you know, the Earth has a, we have plate tectonics, which curiously wasn't an agreed upon fact either until the 60s. I think they tell at the Caltech seismolab, that they used to mark the idea in the Caltech seismolab in the early 60s. Wegener came with the concept of plate tectonics in, I believe in the 30s, based on paleontology, the study of fossils and looking at patterns. And he was laughed out of the room, as scientists can be pretty narrow-minded sometimes, so. But back to the relevance to this mission, plate tectonics basically recycles the formation in history. So, when we have a planet like Earth, we have a good snapshot of what its state is now and some hints about its formation. Of course, we have a lot of data, but a lot of this information, the crust itself gets recirculated every couple million hundreds of years. So, having a planet like Mars that does not have plate tectonics is very useful in that sense to study the history of its interior and maybe learn something about other rocky planets from it. And we will do this with several techniques that we'll talk about. Seismology being the main one, but there are other techniques that we'll be using precision tracking, basically a form of geodesy and heat flow measurements. Now, a little bit about the formation of planetary interiors. Planet, the interior of planets as it says on the slide is comprised of the heat engine that drives the interior processes. It's a dynamic process that shapes the surface, as we talked about plate tectonics on Earth and in other ways where you don't have plate tectonics. An example for Mars is Olympus Mons. When you don't have plate tectonics and the crust is stationary relative to the interior and you have a big heat source that keeps spilling lava on the surface. At one point, you create the largest volcano in the solar system, which is Olympus Mons. It provides many of the necessary conditions for a planet to become and remain habitable as the case on Earth. And it retains the fingerprints of the planet's origins over printed to some degree by its subsequent evolution. Now, terrestrial planets share some common structures that to the best of our knowledge, understanding and models. And we believe that these commonalities of having a core, a mantle and a crust are a result of a formality or a formation sequence that is common to planets as the accrete from material that comes together through gravitational pull early in their evolution. So why go to Mars again? So we have the informational interiors, as I said, only closely related to terrestrial planets, the Earth and the Moon. Obviously know a lot more about the Earth than Moon. And much of the Earth's early structure evidence has been recycled by plate tectonics. And the Moon is pretty small. And you see the different sizes here, the relative sizes of Mars, Earth and Moon. And so we think the Moon may not actually be a very good representative of most rocky planets just because of its size. Mars, however, is large enough to have undergone some of the key terrestrial processes, which we'll talk about in a second, and the formation of the core and the mantle and the crust, this process where materials separate, which we call fractionation. And, but it is small enough to have retained evidence of its early activity. Because it doesn't have plate tectonics, we think that there's the fingerprints of its early formation processes. And that is one of those corny things, is the Goldilocks analogy. We think it's just right, just the right size. All right, so how does terrestrial planet form, or rocky planet, how does it form? So the planet starts forming through accretion of meteorite material. It's basically gravitational pull as more material gathers together. It has an increased gravity, and as it grows, the interior begins to heat up and melts. Then something happens, and after a while, you end up with a planet that looked like Earth or Mars, which has a crust, a mantle, a core, and with distinct non-meteoritic composition. Material differentiates or fractionates, where heavier stuff goes to the center. What insight is focusing on is what happens between the very early accretion to where we are today. And again, because Mars is a Goldilocks, we think that it will give us a pretty good idea of that early stage of formation of a planet that has not recycled its history. This is a cartoon version of an example of the general process of formation where you have molten stuff early on, as we said, from accretion and heating. The metals, which are heavier, sink to the center. You have a metallic core, and then you start getting layering where you have distinct chemical boundaries that where minerals are formed because it's very specific temperature and pressure conditions that relate to when the composition on the planet and its size and of course its history, where it is in the stage of history and its differentiation process. And this process, it depends on the planet, but it will continue to grow and you end up with a more or less quasi-permanent picture of its interior where you have a core, a mantle, and a crust with distinct boundaries as we observe them today. Now, we know very little actually about Mars, as I mentioned, compared to Earth. We have huge uncertainties in the thickness of the crust. I don't think we even know it to a factor of two right now. How big is the mantle and how big is the core? Is it liquid? Is it solid? And these questions are key to understanding the formation of the planet. What state is it in? And since we think this state is actually relatively close to where it was when it formed, what does it tell us about planet formation in general? So let's get to a little bit more specifics of what we're trying to do. So we're looking at the crust and its thickness and layering within the crust, which reflects the depth and crystallization processes of the magma ocean and the early post-differentiation evolution of the planet. So plate tectonics versus crustal overturn versus immobile crust. I don't even actually pretend to know all the details of differences of the models. The point is that the thickness and the layering of the crust tell us something about the composition and the state of the magma ocean early on in the process. The mantle, its behavior, meaning is it convecting? Is it generated? Does it have pockets of partial melt? Determines the manifestation of the thermal history of the planet. And it depends directly on the thermal structure and its stratification. And the core, its size and composition, density will tell us pretty accurately what it's composed of. We know the density of the Earth core and we'll talk in a little bit about how we know the density. Reflects the condition of accretion and the early differentiation and its state versus liquid or solid reflects its composition and the thermal history of the planet. So what insight is trying to do is answer all these questions. And in what we call level one requirements. So the level one mission requirements for all NASA missions, these are the requirements that the mission must achieve to be successful. They're cast in stone and everything in the mission design flows from those requirements down to the specific performance of the seismometer, its sensitivity and how it's going to be deployed, how it's going to rest on the surface, what is the spacecraft going to do everything flows down from the level one requirement. And some of you may know this, but basically you have the level one requirement that is set by the science and it goes all the way down to level five, which is where the engineers are concerned. When you verify that, that's what the engineers are concerned with. When an engineer verifies that the require when level one requirement is met, they're really going down at the roots of the tree at level five and it flows down up the tree all the way to level one. That's how you verify that the mission can meet its level one requirements. So what are those level one requirements? Dermant crustal thickness to within certain accuracies. It's not listed here, but this will be a bit of an Eiffel. Large-scale crustal layering, seismic velocity in the upper mantle, solid versus liquid core, core radius, density, heat flux, rate of seismic activity, epicentral location, rate of meteorite impact. And I will just give you a hint that since the level one are cast in stone, if an instrument through its verification validation program appears that it's not going to meet its level five, four or three requirements, you're not going to meet your level one requirement and you might get a mission delay. All right, so let's talk a little bit about the payload. So Insight has several, quite a few instruments actually. The main instrument is size. And these days we're in the base of acronyms and I believe, I don't remember all the acronyms. I think this is seismic experiment of an interior something, it's a seismometer. And right here on the picture, it's covered with a wind and thermal shield, WTS. And that is done because this is definitely not how we do seismology or we would like to do seismology anywhere else. This is a necessity on Mars. Typically a seismic station on Earth, you'll take your very sensitive seismometer and we'll talk in just a few minutes about how sensitive is set, very sensitive. And you either dig it on the ground or preferably you go to a mine shaft or a vault and where it's very quiet and thermally stable and you leave it there. You can't do this on Mars for practical reasons. So we have, we place it on the surface. Mars has an atmosphere, albeit very thin atmosphere. It still has atmosphere, winds, dust storms, sand storms and dust devils. And they all generate seismic noise. You have to protect the seismometer and that's why you have this wind and thermal shield on top of it. You have the heat probe experiment, which we'll talk about. This is, so I'm sorry, the seismometer is provided by the French Space Agency. This is a JPL, the WTS here is a JPL design as is the robotic arm that places all these things on the instrument, on the surface. The lander is a Lockheed Martin lander that's based on the Phoenix lander. The heat and thermal probe is provided by this German Space Agency. And it's basically a mole or a penetrometer that with an internal self-hammering mechanism that penetrates the interior, basically one millimeter at a time down to a depth of about five meters. And it gathers behind it a tether that is in which thermocouples are embedded. So it measures the thermal gradient from the interior of the planet. And it has to go down a few meters to get away from what we call the skin effect, the effect of both diurnal and seasonal effect. We're gonna be on Mars for a full year. We also have RISE. RISE, these are basically two radio antennas that provide the direct to Earth link. And this is the geodesy, space geodesy experiment I mentioned. We basically, it's measuring a Doppler shift of the radio wave direct to Earth from which we will track the procession and mutation of the Martian, of Mars, which tell us something about the state of the core, actually. The popular analogy that people usually give is a, is the difference between spinning a soft boil and a hard boil, an uncooked and a hard boil egg, where if the state of the interior is liquid, they spin in entirely different ways. And now for diet co-commercial, sorry. All right. Okay. There are other instruments, auxiliary instruments. What you have here, the pressure inlet is actually a very sensitive microbarometer and it's actually part of the seismic experiment. It's not just for weather. As I mentioned, Mars has an atmosphere and we know from Earth, pressure variations do generate seismic signals and we want to not get false positives. So measuring the pressure with high degree of accuracy is very important for the seismic measurement. In fact, barometers are standard practice on most high quality seismic stations on Earth. We have two wind sensors. We have cameras. We have a scoop that we may or may not use. It's a part of the heritage design of Phoenix and we have here a grapple with which the arm picks up those instruments from the deck after it lands and places it on the surface of the planet. All right. I'm going to talk a little bit about seismometers and some of you may know that but the risk of teaching you something you know. A seismometer system is actually a very simple principle. It's either a mass or on a spring as shown here or a pendulum or some combination of both. And the idea is if you have the mass and it's anchored to an inertial system when that inertial system moves, you get a differential motion between the mass and the inertial system and that's your seismic measurement. That's how much the ground moves. The problem starts, the problem has always been in the details on how to make these things practical. A seismometer is very sensitive to a ground motion that is shorter or higher in frequency than its natural frequency. Think of a pendulum. If you move it really fast compared to its natural period, let's just say it's also late once per second. If you move it really fast, rather than that you'll get the differential motion. If you move it really slow, the differential motion between the mass and the inertial system will be almost unnoticeable. And in modern seismology since the 80s, we have fixed that with some tricks of the trade that basically sensitive electronics made a huge difference. And also feedback system made a great contribution and in most modern seismometers as inside is and it's modeled based on terrestrial seismometers, though for different gravity, so you have to design it for Martian gravity and conditions. The mass actually hardly ever moves. You constantly put feedback back into the mass to try to prevent it from moving and all you measure is how much current you have to feed into the system to prevent the mass from moving. And that current is proportional to ground velocity. And that's how we do seismology on Earth and that's what we'll do on Mars. Now, how sensitive? This is actually an example that I don't particularly like that people would say that we can measure displacements roughly the size of a hydrogen atom. I find it a little bit hard to explain because we don't measure atomic phenomena with seismometers, but just maybe to illustrate this, you think about the very tiny motion you'd get from a tide, like the solid tide or from a person who's jumping up and down a couple of miles away from your station, a good seismometer under good conditions should be able to easily sense that. A more, actually, this is real data of how that illustrates how sensitive seismometers are. We installed a seismometer in Littleton, Colorado, in the Odenver where Lockheed Martin was building the seismometer, I'm sorry, the lander. And we installed a seismometer there because we were going to test the flight seismometer, the inside seismometer there, and we needed a reference seismometer to measure the building noise and everything else. Now, we're in Colorado. What we see, so this is what we call a time spectral plot. So what you see here is time and the tick marks on the bottom, this is 50,000 seconds. So we're looking about a week's worth of data on the x-axis and the frequency between zero and 0.5 hertz. So right here, 0.1 is about 10 seconds, five seconds of ground motion. And when we look at a time like this, events have very distinct signature. We can identify things like these. At this frequency band, and remember this, actually it's important for what we're going to talk about later, so here's 20 seconds, 10 seconds. This is really where the bulk of seismology is done, at periods between, I would say, a few tens of seconds to one second. We need long waves to detect, to study structure on the planetary scale. We need waves that elastic waves of several kilometers length, and they translate to waves of these periods. You'll also notice here this kind of fuzzy band here. That fuzzy band is the ocean. Now remember, we're in Denver and we see the ocean. And see the train now, you could actually see that this band here, you'll have to take my word for it, is a Pacific Ocean swell system, where this one here is an Atlantic Ocean swell system. They have distinct signature and they're slightly different frequency content. But that's how sensitive these seismometers are. And it's both a blessing and a curse on earth, a blessing because when I put the seismometer down anywhere on earth, one way to check if it's functioning is do I see the ocean? It's a curse because when I try to test a seismometer for Mars, all I see is the ocean on earth. So how do you test the seismometer that is going to go to Mars on earth where you have all these noise sources? So the way we do it is by basically differentiating, take two identical seismometers or seismometer and a reference seismometer and differentiate the noise. So let's look at the seismometer that is on Mars. So this chart is a bit of an Eiffel. This is what the actual seismometer looks like before, as you'll see later, it's covered with a thermal blanket, not the wind and thermal shield that goes on top of it, but a thermal blanket. And this is an evacuated sphere. The seismometer is a near perfect vacuum. And this is what the actual seismometer looks like. You have this leaf spring. It's an inverted pendulum. That's actually the pendulum body. VVB stands for very broad band. We want the seismometer that measures the very broad band of frequencies, as I mentioned, for maybe 100 seconds to one second. So we have three of those and because we have three components of motion up and down North, South, East, West. The nice trick about this one is that these are all identical to each other. And the reason is it's basically a configuration of a cube that's tilted on one of its points and the decomposition into vertical North, South, East, West is done basically through the electronics. We also have backup short period seismometer. There may be a factor of 10 less sensitive but a lot smaller and they reside in these boxes on the outside of the sphere. You see one of them right here. You see another one right there. And then this whole sphere is sitting on a leveling system that can take up to a 15 degree slope at the landing site. We have to be very close to being leveled on the surface of Mars, as is true for any seismometer to make good measurements. Other components of the size system. So we have the E-boxes, basically the data logger and the thing that logs the data and then communicates with the spacecraft to send it to Earth. We have the R-web, which is, as I said, the thermal blanket, the wind and thermal shield with its skirt thing that again, if we land on a slope it can adjust itself or even to some rocks. It has some flexibility to still seal against the ground. We have a tether, a long tether that connects the seismometer to the spacecraft. We don't wanna stay on the spacecraft like Viking did because as Viking showed us, we'll be sensitive mostly to wind noise. So we place it on the surface and it has to be connected to the spacecraft somehow and the solution that the engineers came up with is a tether. It was contemplated early on whether to do it wirelessly. There's pros and cons. There is a load shunt assembly. I probably, for the interest of time, I won't bore you with the details. It's just a way of isolating tether motion from the seismometer and the tether is coiled up inside the tether box. All right, so what are the signals we're gonna see? Well, we have some rough estimates of Mars seismicity. Basically, we're looking at, here are the magnitudes on top and there are models that tells us how much energy, in a sense, what we call moment, seismic moment, which is sort of equivalent to seismic energy, not exactly, but it's okay to think about in terms of energy. How much moment will be released in a Martian year? And we have models of the seismicity that indicate that it'll probably be about a factor of a thousand less than on Earth. Give or take quite a bit. One of the things we want to constrain is exactly the number of quakes that we think, if we don't see any quakes, we would be pretty surprised. There'll be a tide from the tiny moon Phobos that will generate some ground motion, just like on Earth. We have, of course, the ocean tide, but we have also a solid Earth tide as the Earth gravity corresponds to the position of the moon and we'll have meteorite impacts. And we anticipate, based on our knowledge of impact rates, that we should be able to see maybe a dozen or two impacts with our seismometer and perhaps after identifying them with a seismometer, talk to some of the orbiters and try to look for the actual impact point. And we'll have atmospheric excitation of seismic ground motion that actually can also be used as it is on Earth to study the interior. We're going to have a seismic, a single seismic station. And on Mars, I'm going to actually jump ahead to this slide for time. On Earth, we have the luxury of having a seismic network. We couldn't fit a seismic network on Mars. It was not in the cards and not in the budget. You need multiple landers. There have been concepts and people have tried to fit it within the cost cap. It's just not doable. So people had to do some smart things in order to be able to do seismology with a single station. So how do we do this? Here is your station, right here, this triangle. Here's a quake. And the quake generates, as you probably remember from high school, P waves, S waves. Surface waves. Now, if quakes are large enough, the surface wave propagates in all directions. So you'll get, we call it R, because it stands for Rayleigh wave. These are polarized waves. They are the largest amplitudes of waves that we observed during a quake. It's the same on Earth. There are surface waves. They propagate only in two dimensions, not in three dimensions like the P and S, what we call body waves, the propagates through the body of the planet. And as a result, these are much larger. They only decay or geometrically spread in two dimensions rather than in three. This is why they're the most destructive waves during a quake. So anyway, we have the first one, the second one. If the quake is really large enough, we can get one that goes one time and one time again around the planet. And you can use all these measurements, the time of the P wave, S wave, R1, R2 and R3, to determine five parameters, the velocity of the Rayleigh wave that tells us immediately something about the crust, the distance, the origin time. Remember, with these, we don't have the exactly, we have relative time, but not origin time. But five parameters, five variables, origin time, the P wave velocity, S wave velocity, you can look at these equations and do some algebra and see that if you have these five observations, you can verify these five variables. And do we think that we'll have big enough quakes to do that? Well, remember, Mars is smaller. So if on Earth, it may take a magnitude seven or so to get this kind of behavior, a magnitude four and a half might be sufficient on Mars. The heat probe I mentioned is going to tether itself into the ground and measure the thermal gradient with thermal couples along it. And that's what it looks like. It has a self-hammering mechanism. And here's a picture of the tether with the thermal couples on it. It's actually, when you hear it going, the little hammer inside sounds like almost like when you're pulling on the trigger of an unloaded pistol. All right, I mentioned rise. Again, this is Doppler measurements of the position of the seismic station on Mars relative to Earth, up to an accuracy of 10 centimeters. And we'll tell us something about the procession and mutation of the planet from which we can do something about the state of the core. All right, I'm going to jump a little bit ahead We may, if you're interested in learning a little bit about the delay, let's leave it to the Q and A's. I want to give enough time for Q and A's and I see that I'm running out of time. But I'll be happy to talk about this and how it's really all stems from our level, our very strict level one requirements that I mentioned early on. Inside will launch from Van Burt, California. Again, sorry, I apologize for the corny cartoons. If you're in the area, you should be able to see it. You should be able to see it from LA. It's going to go in the trajectory due south from Vandenberg. And it's going to be six months from cruise, landing November 26th, just after Thanksgiving and deployment that the last two months. And I'll show you a little video of that. They're much sped up in just a minute. One more is here on the surface and nominal end of mission November 24th. But usually if all goes well, we hope that, and we hope they will, we hope to extend the mission. All right, landing sites is a very flat and boring site. We want to be away from obstacle. We want to be in a place where the HP cube, the pentatometer can go in easily five meters. It may not be actually ideal for a seismometer. We prefer hard rock, but hard rock landing is risky. So we have to compromise there. And then the placement, unlike Viking will be on the surface of the planet. And we're almost done, but I want to show you a sped up version of the deployment sequence. And what you see here is the robotic arm with its grapple picking up the seismometer with its thermal blanket and placing it on the surface. Now, in reality, the rate of the arm movement would be more something like my arm here. So this is very sped up. Also, there are a lot of decision processes. Like do I release? Is it time to release? Is it okay to release? That will involve Earth in the loop. All these add up and all these critical junctures in the deployment process that will make it take a couple of months to commission the instrument. Here's the heat, I'm sorry, the wind and thermal shield, the WTS, and it's placed on top of the seismometer. They're not touching it. And then the arm will go back and pick up the thermal probe and they'll place it about a meter away from the seismometer. And you'll see it's dragging its tether. By the way, you see here the tether of the seismometer and its box that's sitting right under the lander deck right here. The power is solar as Phoenix was. And with that, I'll finish with this last image from the Spirit lander with the hope that we will learn something about Earth and other rocky planets by looking deep inside Mars. Thank you. Brian, Dave, I'll be happy to take questions. Oh, great. Well, thank you very much, Sharon. This is really fascinating as originally a geologist of, I have a great fondness for missions that are geological in nature. We don't have any open questions quite yet, but I have a question that I thought of a while ago. And so you're hoping to notice whether there's any differentiation within the interior of Mars. Well, one of the things a lot of times surface rocks can give some sort of an indication whether or not there's differentiation. Is there any evidence from any of the rocks that have been investigated by any of the rovers that suggest differentiation that you know of? The short answer I do not know, but I think that most, I'm guessing here that most of the rocks that have been examined by the rovers, and especially by Curiosity, if they come from the interior, deep interior, they'll have to be excavated through an impact cratering. They'll have to be pretty big or come through lava flows. I don't think that either of those come from very deep in the interior, but I'll have to double check and refresh my memory to give you a better answer. Yeah, that's my best guess here. Yeah, I know that there's a couple of different kinds of differentiation and certainly as far as I can tell, there's no signs of magmatic differentiation, which would be an indication of whether or not there's a greater differentiation. Right. Well, so many, many lines of evidence that are possible. Yeah. Willie's got a question. Are there any instruments aboard to detect water? Not directly. There's a magnetometer that I didn't mention. There is a radiometer that measures thermal emission from the surface. There is nothing that will directly detect water under the surface. We will use the hammering from the thermal probe to do what we call a geotechnical study. It was the same kind of study you would do when you were trying to dig foundations for a new building, but that would be of the very shallow, maybe top 20 meters. It won't penetrate much deeper beyond that. We are, you know, the astronauts on Apollo actually did a seismic survey. They actually took mortars with them and fired them and they had a line of geophones. They did an actual seismic survey. Maybe one day we'll do something like that on Mars. Well, we'll have to take an oil exploration geologist up to our geophysicists up to do that. They're really good at doing things like that. Yes, exactly. Dan has a question. What earth insights, I know you covered this to some extent, but what earth insights are they trying to get from this mission? What do you anticipate learning about earth from this? I think it's sort of indirect what we learn about earth. As I said, we want to learn more about the formation of rocky planet, especially early in the revolution. I think maybe one intriguing question is, is the role of plate tectonics in sustaining life? The thinking is that Mars early on in its formation was maybe reasonably hospitable to life. It's on the edge of the habitable zone in the solar system. So, you know, as usual humans think or sometimes think, why are we so special? What's so special about earth that have plate tectonics for other planets, do not? I know that the astrobiologists that I've talked to are very interested in that topic. Chris McKay, who many, many people on the webinar are familiar with, has actually had the contention that plate tectonics is a construction of the planet. Is a constraint for life without that global recycling mechanism that you won't have an atmosphere that's sufficient to sustain life. So Stuart has a great question. Do you have any plans in the event that Mars is seismically inactive or at least not sufficiently active to generate detectable quakes? So we cannot generate detectable quakes with insight. We have floated concepts of putting a cannon ball on future missions and drop it. Actually, if you think about the error ellipse, there's actually very little risk of hitting insight. The cannon ball that comes in ballistically into the planet, you could get pretty close and at least with a 10 kilogram ball, tungsten ball say, you'll be able to constrain the thickness of the crust at least locally. That's, we don't have any concrete plan of doing that. This is just a concept. Also future missions like Mars 2020, they carry with them ballast masses for balance and they drop them. Though we think that it'll probably not be, it'll be too far for us to see it. However, we know dust devils generate seismic signals. We know the atmosphere generate seismic signals. One of the hardest topics in terrestrial seismology is what we call noise tomography using the background noise to study something about the interior. So not quakes, but if you just, you can actually make sense of the noise if you listen long enough. So I don't think it'll all be lost and it would be extremely interesting to find out that Mars is not active, assuming we can prove that it's not because our seismometer doesn't work. Yeah. Well, you could always do an L cross impactor and that would probably generate a nice little signal. I suspect too. Yes. Linda's got a good question and I know that we're running a little bit late here, but I think we've got a couple of interesting questions here and so if you don't mind. Yeah, not a problem, I can say that. So Linda asks, what is the source of the seismic activity at Mars? And I think you alluded to that. Is it expected to come from meteor impacts alone or are there other causes of seismic activity? And I think that you alluded to that. Right, but maybe it wasn't particularly clear. So the main sources of seismicity in a non-tectonically active, non-plate tectonic planet are thermoelastic. It's basically thermal relaxation and thermal variation of rocks. And so just over time, just from the cooling of the crust and the overburden pressure of structures on the Mars, occasionally you get cracks. It's a much slower rate of activity. The moon has that, but at a rate that is dissipated to be even lower than Mars, the moon actually has a lot of tidal quakes deep in the interior from the earth tidal pool. It has a lot of rocks cracking on the surface, but the main source of seismicity on Mars would be more of just thermal cooling of the crust. And as you mentioned meteorite impacts, they're probably the two main sources. We anticipate, but we don't know really, models suggest that during a Mars year, we should be able to detect anywhere between maybe 20 to 150 quakes. Okay, well, we've got one more question. We'll make this the last question for the evening. So Jesse asked, what part of earth's geology gives it its magnetic field and what differences do you expect to find based on Mars's magnetic field? So the earth's magnetic field is generated by a dynamo mechanism, which the earth has a solid iron core in the liquid metallic core that circulates around it and generates a very powerful electromagnet. Obviously you have a, it's just like when you have a right to a new kid and you take a nail and wrap a coil around it and put current through it, it becomes magnetized. It's the same idea. We don't think Mars has that. So Mars doesn't have a strong magnetic field. It might have had some magnetic field in the past and maybe some remnant of that is locked in rocks that were magnetized when they were molten and then froze. We will measure the magnetic field or local magnetism, but it definitely doesn't have anything like the magnetic field of earth. And that's by the way actually thinking as one good reason why we have protected life on earth as the magnetic field shields us from from charge radiation from the sun and the galaxy. Well, great. Well, thank you very much. I found this incredibly fascinating. As I said earlier, as a geologist, I have a fondness for presentations like this. So thank you very much, Jerome. This is eminently fascinating. And I think that we had some great questions from the participants. Yeah, I thank you. And thank you all for your time and your patience. And Brian, Dave, you have my email, but please feel free to share it. If people want to send me questions or maybe I didn't explain something well enough or they have thought of additional questions, they'd be happy to get answers for them. And if you're willing to share the slides and so we can put it up on the Night Sky Network website, we would like that. So maybe you can check with your PI and get permission to do that. We would appreciate that. We'll do that. Thank you.