 It's one o'clock on a Monday afternoon, so you must be watching Think Tech Hawaii Research in Manoa. Good afternoon. I'm your host, Pete McGinnis-Mark, and today we have a fascinating program. This is all about space weathering. So joining me today is Laura Corley, who is a NASA Graduate Research Fellow at the University of Hawaii at Manoa, and her adviser, Jeff Gillis-Davies, who's an Associate Researcher, also at HIGP at Manoa. And so let's get started. Today's topic is space weathering, and I'm particularly interested in Laura. Well, I've heard of space weather on that, I believe, is what produces the Northern Lights. Absolutely. But what is space weathering? What's the difference? So the difference is that space weather is how the particles from the Sun interact with our magnetic field and also the atmosphere, which is what produces the Northern Lights, whereas space weathering is actually the geologic process that occurs when planetary bodies do not have an atmosphere or a magnetic field. So these are things like the solar wind, which are hydrogen and helium atoms that impact the surface, and also micrometeorites or dust-sized particles that can impact the surface of the planet. And we have a nice cartoon, the first image, I think, shows the Sun. And if we could have the first slide, yeah, here we go. So on our left, we've got a cartoon of the Sun and lots of things streaming out from the Sun. And then we've got the Earth on the right. Right. So the Earth has, you can see the blue lines are the magnetic field lines, and that shields the Earth from these hydrogen and helium particles. But the Moon does not have an atmosphere or a magnetic field to protect it from these particles. And the Moon, so far away from the Earth, that Earth's magnetic field does not protect the Moon. Correct. All right. So space weathering would perhaps be the long-term effects of this solar wind, say, measured over geologic timescales. Is that correct? That's correct. So this process of micrometeorites, as Laura said, and hydrogen and helium hitting the surface of the Moon or Mercury or asteroids that are out there in space, actually changed the surface properties of those objects. And that's something Laura is studying. She's studying what happens, what are the effects, and how we can detect it. But hydrogen and helium, they're really light. They don't weigh very much. Atoms, right? They must be going very fast to do any damage to rocks or to any other geological materials. Right. So the solar wind is flying by at about 700 kilometers per second. So that's 500 miles a second. Yeah, about 500 miles per second. So it's streaming by. And when it hits, it gets implanted and actually causes damage to the crystal structure of the minerals on the surface of these airless bodies. And the effect is to make a glassy, amorphous surface and also to change the chemistry. And amorphous for our viewers means that it doesn't have any structure, it's a glass. Yeah, so you can think of it as a glass. It's a glass. And this, you know, rim thickness is only, you know, 100 nanometers. So, you know, it's extremely... Now with a human hair. By a lot. By a lot. By a lot. Yeah. So what Laura wants to do is study how the process happens at the poles of the moon because the temperature at the equator is higher than the temperature at the poles. And what that means is the minerals being cooler might not change as much as the minerals at the equator. But just to back up, it's these hydrogen and helium atoms zipping along at 500 miles a second, hitting an object. And the key thing is that the moon, or presumably something like an asteroid or a mercury, because it lacks an atmosphere and it lacks a magnetic field. So we don't have to worry about this kind of space weathering. This geology doesn't happen on Earth. Correct. Or Mars or Venus. It also happens on Mercury and asteroids as well as the moon. Okay. And I'll ask you later on, is it the same rate? Is it uniform? Right. But you've brought along, in the second image, Laura, I think we can see exactly what the, quote, impact is of some of these little projectiles. Right. So what do we have here? Well, process number one was the solar wind. But process number two of space weathering is micrometeorites. So we all know what meteorites are that fall on Earth from the leftover material as the solar system formed. Well, actually, there's dust-sized meteorites that can also fall. And they will create these little craters that we see in our image on the surface of the rock. And the little craters are those sort of white dots with a black counter. Yep, the circular whitish areas. So the black is a glassy impact melt that splashed over this rock, which was collected at Apollo 16. And then these little dust-sized grains were hitting the moon at 20 kilometers per second or about 15 miles per second. And they make these little impact craters. And you're studying the geological effect of all these little holes forming over millions or perhaps even billions of years. Is that correct? Correct. These little holes as well as the melt and vapor that's deposited from the impact. Why do we want to know that? Well, we want to know this because as that surface changes, it can change the reflectance of the material. And the reflectance of a planetary body is one way that we tell what the composition is. We need to understand the space weathering process in order to know the starting composition of a planetary body and how that composition has evolved over time. I see. And does this actually give you a clock in the sense that if you know the rate at which these atoms are streaming out of the sun and they're hitting a surface, presumably if there are more holes on the rocks, then it's an older surface? Correct. So you can do things like count the density of the solar flare tracks on the rock to understand how much time it has been exposed to the space environment. And you're studying predominantly space weathering on the moon. Correct. We could look at Mercury and I'll ask Jeff about that in a few minutes, but the moon presumably is a really good place to do this investigation simply because we have samples with known ages. We do have samples of known ages and also we currently have a mission orbiting the moon called Lunar Reconnaissance Orbiter so we can look at the data from that and understand space weathering as well. And speaking of missions, Jeff, you were part of the messenger spacecraft which went into orbit around Mercury in 2010 or whenever it was. Do you see the same kind of space weathering on Mercury as Laura was seeing on the moon? Right. We do. The Mercury being much closer to the sun is getting blasted by the solar wind at a higher rate because it's closer. It's also at a higher temperature and the surface temperature is about 400 degrees centigrade of oven temperature and that also affects the minerals. And then the micrometeorites, because that dust is falling into the sun, it's actually picking up speed. So by the time it gets to Mercury, it's now traveling 40 or 50 kilometers per second or 30 to 40 miles per hour per second. And it's doing even more damage because it's mostly kinetic energy that causes the damage. Okay, I'm presuming some of our viewers know that say Mercury always has one side facing the sun, which means it would get blasted by solar flares, but the far side of Mercury which never sees the sun, is that exclusively micrometeorite bombardment? It's not synchronously locked like the moon. It does actually rotate with two to three spin orbit rotation. So it does have poles that, what we call the hot poles. So those are pointed at the sun at its perihelium point and then the other parts are pointed at the apelium point, so they're a little bit cooler. But that does interestingly enough actually help migrate different elements around, more volatile elements. So you can't do a comparison trance between Mercury and the moon and say, ah, this must be solar weathering, this must be micrometeorite bombardment? No, not that way. The Mercury does have a small magnetic field that does potentially hold off some of the solar wind, but it's not enough to really make that much of a difference. But it does have some interesting features. The magnetic field lines go into the poles of Mercury, so it actually concentrates some of the solar wind, those hydrogen ions coming in. And it could actually create more damage at the poles and at the equator versus the moon without the magnetic field. It's always more complicated than you, right? It is a bit more complicated. Yeah, and then there's the chemistry, you know, Mercury's chemistry is a little bit different. It has more sulfur in it and lower iron than the moon. So that also, you know, creates some different effects. Right. Let's take another look at a slide, because I believe you're a NASA fellow, right, which means if we can go on to the next slide, what we would like to see. Here we're looking at more of this damage. Now, did you collect this particular image? And it's the scale is in nanometers, right? That's NM. This is actually from a lunar soil grain, correct? That's correct, yep. So this is the actual space weathering process as it occurs on the moon. And the substrate there is that glassy rim that Jeff mentioned earlier. And the white circular regions are actually the iron metal that's deposited in belebs as the material is melted and vaporized from space weathering. And any lunar sample that the Apollo astronauts returned would look like this if we did a thin section? So the lunar soil samples. The lunar soil samples, yes. Not the big rocks or anything like that? Not to this degree. They have a glassy patina, but not to this degree. It's not as a mature sample that's been reworked as much as the soil is. So this is what changes the reflectance of the material. So if you're taking color images or multi-spectral images of the moon for more of it, these kind of glassy surfaces would actually change the apparent question point. Right, so you get a darker material. And also a redder material, meaning in the longer wavelengths, it's brighter than in the shorter wavelengths of light. And would you go to monocaya to make these measurements with one of the telescopes? Or do you have to have a spacecraft in orbit around the moon to make sufficiently precise measurements? You can also look at telescopic data as well and get reflectance. I think we've got time just for one more slide. And as I was indicating, I think Laura, you were a NASA fellow. And I believe this is the actual instrument. And in the second half, we'll hear a little bit more about this. But what is it that we're looking at here? This is the NASA Ames Vertical Gun Range in Mountain View, California. And this is a high-impact gas gun that fires projectiles at about six kilometers per second or 13,000 miles per hour. OK, so much faster than the solar wind? Not much faster, but at a comparable speed to what micrometer I'd sit at on the planetary bodies. And how big is it? We sort of see the bottom left. We've got a stepladder. So this is quite a big piece of equipment. Yes. So if you zoom out, the whole gun actually goes up to the ceiling of this building. So it's about two stories high. The orange apparatus is bigger. Jeff, this is terrific. But a graduate student at Manoa, you're able to get lower to get access to this kind of equipment. Is this a special opportunity, or do other researchers have access to this equipment? All NASA researchers have access to the equipment if they write a proposal to NASA, stating what science they're going to get from it. It gets peer-reviewed. And whether it has a high enough science rating, that PI or principal investigator will get funded and can use this apparatus. And this is one of the great things that we get to use so that we can train the next generation of scientists and how we do our teaching with hands-on science approaches. I'm going to ask you in the second segment, what you hope to do career-wise with all this skill set. But clearly, this is a wonderful opportunity. And presumably, that's all part of your NASA fellowship. If you get NASA money to do your PhD, then you can go and use NASA facilities. As a graduate student, we have those opportunities. Terrific. OK, well, we're about to take a break now. So let me just remind all our viewers, you are watching Think Tech Hawaii Research in Manoa. I'm your host, Pete McGinnis-Mark, and today's guests are Laura Corley, graduate student at the University of Hawaii with her advisor, Jeff Gillis-Davis. And when we come back, we'll hear a bit more about some of your experiments more. So we'll be right back, so don't go away. Veteran, my victory was finding the strength to be a champion. My victory is having a job I can be proud of. At DAV, we help veterans get the benefits they've earned. My victory was finishing my education. My victory was getting help to put our lives back together. DAV provides veterans with a lifetime of support. My victory is being there for my family. Help us support more victories for veterans. Go to dav.org. And welcome back. You're watching Think Tech Hawaii Research in Manoa. I'm your host, Pete McGinnis-Mark, and our guests today are Laura Corley, graduate student at the University of Hawaii with her advisor, Jeff Gillis-Davis, who's an associate researcher also at the University of Hawaii. Now, Laura, we saw that wonderful photograph of the gun at NASA Ames, which is just south of San Francisco. I believe you brought a video which shows what you can do with this piece of equipment. That's right. So you can take high-speed video at the Ames vertical gun range. So we have a video to show of the actual impact. So this is a powdered material. It's powdered minerals. And you can see the ejecta coming out. It actually forms a crater. And that small circle there on the surface is a quarter for scale. I was wondering what the scale of this is. And the projectiles coming in at a couple of kilometers a second, is that what you were saying? Correct, six kilometers per second. Six kilometers a second. It's pretty fast. And we have those large particles in that ejecta coming out are actually similar to what's created on the moon. And they are called a glutinous. They're melty aggregates of the material that was impacted. And the surface of the moon, the rocks there would have experienced this kind of impact for millions, if not billions of years, if they're really old rocks. Is that correct? Correct. So that's what's really doing the damage. And that's what you can detect with some of your spacecraft color data or your multispectral data. That's right. And also in Apollo samples. And the Apollo samples. And these velocities may not sound all that fast because you can drive 60 miles an hour, which is actually a lot slower. But this is actually a lot faster than a bullet. About 10 times faster than the average bullet. If you shot a bullet into this target, it would just make a small hole. What you're seeing is these little particles which are actually a fraction of an inch. The original diameter was about eighth of an inch. It gets broken up into fragments that are much smaller than that. And they're doing this damage by actually exploding. They release their energy so quickly. What you're seeing is a little explosion that makes a crater about six or eight inches across and about three inches deep. And Jeff, we're seeing video, but this video must be recording at a five frame rate per second, right? Right. Any idea what we're doing? I think it's about 60,000 frames per second. 60,000 frames per second. And now we're playing it back much slower. So presumably all of this would be over in half a second, if not less than a fraction of a second. When it happens in real life, you don't even see it. You don't even see it. You hear it. You hear it. Yeah, you hear it. But on the regular speed. And how many of these experiments did you conduct? So we shot, I think, 16 shots with the gun over a five day period. So you can get like five done. So three done per day. Yeah, max three per day. It takes that long to set up the equipment. And you actually fire into a giant vacuum chamber. So the air has to be pumped out of the chamber before you fire. All of this is done in a vacuum. It's all done in a vacuum to simulate the lunar environment. What a wonderful experience that must have been. Are you planning to go back? No plans yet. I've switched gears into doing the experiments of space weathering using a laser to simulate space weathering. So a pulsed laser is able to melt and vaporize material, much like the micrometeorite impacts what on the moon. And you can do this at Manoa. Yes, we do that in Jeff's lab at UH Manoa. Wonderful. So the laser. I think he brought along some slides of the equipment. I'm not sure if it's the next image or whether it's. We can bring that up and Laura can speak to it a bit. But the advantage of doing it in our lab is, we only use about a half gram of material. Controlled experiments. Well, is this the equipment? Yeah, I think that slide was the equipment, yes. So you can see we're at a much smaller scale. This gold chamber is our vacuum chamber that Laura can cool versus that other huge chamber that we use that aims. That used about 50 kilograms of sample. So because we use less sample, we can do space weathering more quickly. So the laser is up at the top left. And then where again is the sample? You've got that red laser beam. Yeah, it hits the mirror. And the sample is sitting in that gold chamber. In the thermal chamber. So you do controlled experiments changing the temperature. That's right. We can use liquid nitrogen to cool that chamber so that temperatures get down to about 80 Kelvin, which is around negative 300. And you can do this in the vacuum as well. Yes. It has to be done in the vacuum for the cold. Very good. Amazing piece of equipment. I believe, Jeff, you put this all together, didn't you? It's part of a NASA project. Yeah, it was part of another grant that we had. And Laura and I put it together, some trial and error. We had the chamber from earlier experiments that we retrofit a little bit to the purposes of trying to understand what happens if the same material is at a lunar pole or basically a colder temperature. Does it respond similarly to material at the equator? So temperature variations, even if it's way below freezing of water, the temperature variations across the moon really do have an influence on the type of chemistry you would expect for the glass content. Yeah, well, we believe the low temperatures kind of reduce the amount of space weathering that occurs. We might get less melting and vaporization at low temperatures compared to warm temperatures. So the material isn't maturing as fast. So you're looking for spatial variations across the moon from the equator to the two poles. Is that great? Yeah, that's right. And actually, we see with the lunar orbiter laser altimeter, it measures increased brightness with colder temperatures. And one thing that's causing that is the presence of surface frost in the polar regions. But also, as you move towards the poles, there's a trend that likely indicates reduced space weathering. And you've got another image from the lunar reconnaissance orbiter, I think it's two globes, which you can show us coming up on the screen. Here we go. And so we're seeing diviner is the instrument. Is that correct? Yes, diviner. OK. And we're looking at the left-hand side is daytime, and nighttime is on the right. So they're really very cold, correct? You were looking at? Right. So the temperature range at the equator is around a max of 300 Kelvin during the day or 300 Fahrenheit during the day to negative 300 Fahrenheit at night. So that sees the biggest temperature swing. But if you look at the polar regions, they are much colder in general. So they get actually as low as about negative 400 degrees Fahrenheit. Wow, quite a difference. And the stripy nature of these images are presumably the orbital trunks of the spacecraft or how you process the data. The data collection, yes. So with the hotter surface temperatures, it's closer to its melting points. So when the impact hits, it can melt and vaporize more material than an impact that hits closer to the poles. And that's what Laura is seeing in her data that I think she has some spectra that she can show. The next slide should show, I think, what effect you're actually talking about. Is this why the brightness is the function of the temperature? Yeah, so this is the data from the lunar orbiter, laser altimeter, that shows this increase in reflectance at 110 Kelvin is likely ice. But at the higher temperatures, we're still seeing this trend that needs to be explained. So it's probably reduced space weathering, causing the brighter areas. And for our viewers, room temperature is about 290 Kelvin, something like that. So it expands the range almost from absolute zero to room temperature. Wonderful. I think we've got one other slide which will show us some other aspect of your work. And this is, I believe, where you're seeing this change in temperature. Is that correct? So this is a spectra? Yes, these are reflectance spectra of my data, of the material that we shot with the laser. So the blue line is the cold experiment. And you can see it's brighter than the orange line, which is the room temperature experiment. So this indicates that space weathering at the negative 300 degrees Fahrenheit results in a brighter material compared to room temperature. Well, we're getting towards the end of the show, but I have to ask you, what do you hope to do with all this skill? And you've been and worked with both the NASA Ames gun and your firing lasers in your lab or in Jeff's lab. Where might this take you as a graduate student once you get your degree? So I'd like to continue on in the same type of research. But I'm interested in the OSIRIS-REx mission that NASA is sending to an asteroid. I'd like to work on data from that mission and also potentially the samples returned. So in the future, we can use a special electron microscopy to look at samples returned from an asteroid and look for evidence of space weathering as well on asteroid. Yeah, because we haven't talked about asteroids that much today, but presumably this happens on asteroids as well as the Moon and Mercury. Right, it does happen on asteroids. We know that from looking at the telescopic data. But it's likely to happen at a slower rate on asteroids because micrometeorites impacting asteroids, which are farther away from the Sun, are at a lower velocity. So I understand the OSIRIS-REx is already en route to the asteroid. So you have a career path, right? You have to get your degree and then find some role within this particular mission. Jeff, is this a typical path for graduate students that graduate from Manoa? Yeah, that's what we try to do is get them plugged into a mission that's happening. It's the best way to get the hands-on experience that they need. And it's one of the most exciting things you can do, second only to going there yourself. And hopefully, in Laura's professional lifetime, if that's something she wants to do, she'll be able to be an astronaut. And it's really impressive that the university has the resources and the connections with NASA to both give you access to some of the equipment which you've been using, Laura. But also, there is a clear career path, it sounds, as if once you get your degree, which I understand is going to be this year, next year, in the spring. So you're in the final phase of riding up, I hope. That's right. Is that it? OK, well, this is really great. I'm afraid we've run out of time. So let me just remind the viewers, you have been watching Think Tech Hawaii research in Manoa. I'm your host, Pete McGinnis-Mark. And our guests today have been Laura Corley, graduate student at the university, and her advisor, Jeff Gillis-Davis, who's an associate researcher. Thank you both, Laura. Thank you for having me. Thank you, Jeff. Really interesting talk. And good luck with your career, Laura. Thank you. We look forward to bigger and better things later. So thank you, everybody, and we'll see you next week. Goodbye.