David King: atomic clock it's a long so.
David King: What a welcoming 25% participants here this morning, if you're looking for the session about impact creditors planetary geology and meteorites.
David King: This is the one so so don't leave.
David King: My name is David King i'm a professor in the geosciences department and auburn and I work on impact craters and pleasure in geology and my.
David King: two cultures are Julia Cameron and tone justice and once you say.
David King: Greetings Nigeria first.
Julia Cartwright: So Hello everyone, my name is Jay cutler I am an assistant Professor here at the University of Alabama didn't get the accent fully.
Julia Cartwright: And my work is mainly focused on me try analysis and I have a history of doing work with noble gases and more recently i've been moving into more petrol logical and competition analysis using micro and nano scale techniques.
Colin Jackson : You know i'm calling Jackson from tulane university my research is focused primarily on experimental work.
Colin Jackson : So we recreate the pressure temperature conditions inside of planets to understand the chemical reactions that happen within those bodies.
Colin Jackson : So we do we do work in the lab rather than going out into the field interested in planetary science in general, so looking looking forward to the session.
David King: During the session we're going to share share duties.
David King: undermine the speakers that GSA has assets, you talk for 17 minutes or so and then we're supposed to flash you, you may see something on this.
David King: Or maybe one of us will say something about.
David King: Give me a warning and then i'm so then a few minutes for questions and then we have to move on, so there's only 20 minutes slots, we are in charge of placing ads So please, please be.
David King: aware of that and.
David King: Julie are getting to say anything and.
Julia Cartwright: If you have any questions during the talks feel free to enter those into the chat function in zoom and if you can.
Julia Cartwright: It might be that you come up with a question later in the session and for previous talk if you if you can make sure that you pop in.
Julia Cartwright: The name of the person that the question is aimed at that would be fantastic, and we will try our best to get through those questions.
Julia Cartwright: If you'd like to ask your question in person, and then we can, if you can let us know that and we can ask you to unmute and that would be great and that's the other things if you can try and keep it keep yourself muted during the.
Julia Cartwright: If you're not the speaker obviously during the session that'd be fantastic.
Julia Cartwright: So that we don't get any kind of crazy feedback and if we if we do here somebody's making some noise, we might have to have to hit the old unmute button there, just in case so.
Julia Cartwright: Yes, I think I think that's what I have, and I just to highlight the slide current in front of you.
Julia Cartwright: We are at a, this is a profession, we are at a conference everybody, so we do want to be respectful and we want to be inclusive, and we want to.
Julia Cartwright: also enjoy the scientific research that we're going to be finding out about so.
Julia Cartwright: If you can try and be nice to each other, wants to hear that would be fantastic and i'm sure it will make it a much more.
Julia Cartwright: enjoyable.
session as well.
David King: And thanks Julia.
David King: So.
David King: I assume everybody's got control of their own screen sharing so.
David King: Maybe we can just test it out and see if scott's meters smart.
R. Scott Harris: It is set so that.
R. Scott Harris: that whoever has that up as Julia she has to see sharing first.
Julia Cartwright: Great well, I will stop sharing my screen right now.
David King: Okay, good.
David King: So.
David King: So i'm gonna introduce the first talk and then Julia will take over.
David King: The next three so so.
David King: Our first presentation this morning is as by Scott Harris is of course at different banks that are the man.
David King: said you in that ufo um let's see Richard is the American Nice in New York and an element is an American public university North Carolina, so this is.
David King: A report on on unusual structure and West, Georgia and Scott, and I want you to take it away.
R. Scott Harris: Alright, thanks, David, can you hear me okay Jackie.
R. Scott Harris: Yes, okay great so um we're going to get started with the talking about impacts, with a little bit of a what many of you in the room, probably know and some maybe an introduction to some of you.
R. Scott Harris: But it's important as we go forward here to take exam a look at those things that are diagnostic of impact shock.
R. Scott Harris: indications of hyper lost the collisions with planets in particular earth, as we looked at courts that's.
R. Scott Harris: You know, with the abundance of courts here that's tends to be the thing everyone looks for first and we see good examples of what are called fresh player defamation features that are essentially zones of extreme disorder.
R. Scott Harris: To the point of being a more festival ass and, if you will.
R. Scott Harris: And crystal our traffic crystal African control zones.
R. Scott Harris: We say examples here from a rejected grain from chicks lube and we see examples from brushes there were near David and with tonka.
R. Scott Harris: And we also can have these that are modified that are called decorated player defamation fate features are decorated pdfs.
R. Scott Harris: Some examples here from ferocious you are in France, and you see that now the the planes are defined by individual fluid inclusions.
R. Scott Harris: And this is something that can happen over over times or die genetic effect, but it also happen immediately, this is more of an indication of the.
R. Scott Harris: The chemical environment at the along the entire history of grain, so there are plenty of these that are that, but if they're in very hot.
R. Scott Harris: In this case, you may see that these are from impact glasses, so these were in melts at the immediately after shock.
R. Scott Harris: And so, a lot of times we see volatiles that are essentially drawn into those amorphous zones that are created and another thing that we find as diagnostic are.
R. Scott Harris: are similar but not necessarily a direct result of the oppressive forces involved, but some of the extreme shearing very high strain rates.
R. Scott Harris: And we have here planar fractures but then decorated by these feather features that have been studied extensively by Thomas Friedman, and his colleagues, and this is an example from the matt Wilson structure and Australia and so i'm.
R. Scott Harris: Hopefully you will agree with me that these look like some of those player defamation features, and this is.
R. Scott Harris: The example we have representative of a number of grains that we put out in front of everybody.
R. Scott Harris: For some time, and to say that we had shot courts that was associated with materials that were part of what our colleague at all been had described as woodbury structure and West central Georgia.
R. Scott Harris: And, but we really needed a lot more context to this and that's what we're telling you about today, and so, here we have what we have now.
R. Scott Harris: And, rather than scattered grains that are inside of the same matrix i'm about to tell you about we have abundant rocks rocks that are occurs class you'll see how that sets into context in a moment.
R. Scott Harris: But we have extensive planted planted affirmation features in the form of those decorated player defamation features.
R. Scott Harris: And in this business, we always measure those curses crystal or Africa orientations and compare them to other places, and actually can calibrate to some degree the the shock of the peak shock pressures involved, you see here from Devon french's.
R. Scott Harris: Book traces of catastrophe, you see some examples of these and when Stephen and I look at the orientations of these measured with the universal stage we have.
R. Scott Harris: orientations that are very similar to those around in the 15 to 20 gig or Pascal.
R. Scott Harris: range here and and also just that this is the grain we're showing here is almost at the scale scale is this one from bevins book.
R. Scott Harris: from grain for Moshe with these again these beautiful decorated plant affirmation features.
R. Scott Harris: But we also want to point out that these because we do have routine needles in here and there's nothing to say that I regulated coarse grained can't be shocked and you can distinguish those from one another and that the individual decorations are.
R. Scott Harris: are seen along along the planes, but we have some retail needles that are coincident with personal advocate orientations and some that are plenty that aren't.
R. Scott Harris: And if you just wanted to just kind of get that a little bit more crystallized in your mind no pun intended here for some examples of.
R. Scott Harris: Regulated courts at similar scales here this actually is a grain that noted shop photographer Ted bunch gave me a while back and he was kind of hoping, this was shocked, but you really see that these are these are.
R. Scott Harris: The retail grains have grown and actually start to actually the EC solution not only puts them into place, but then actually starts having some secondary growth off of those and then here is an example from a.
R. Scott Harris: known impact structure of where we have those same fluid.
R. Scott Harris: inclusions here that are decorating the planet affirmation features and so again here, we see plenty of examples of planet information features, but also having an having some crystal Africa controlled and so i'm not so crystal graphic controlled a particular routine in the picture.
R. Scott Harris: These are coming from now pretty abundantly identified courtside class that exists inside I truncate that chair indicate.
R. Scott Harris: is one of the more unusual rocks occur in Georgia and the pine mountain terrain and we have.
R. Scott Harris: just some of the representative examples there of what we're looking at and where those are the grains we're talking about come from, and then the distribution of those trying to kick melts you see here.
R. Scott Harris: With the in red, and this is that you know from one to 500,000 scale map, so you kind of have to then.
R. Scott Harris: continue to look around and see little dots and they're plenty that are have individual pieces aren't to map.
R. Scott Harris: And really this is much more complex and then any of the mapping that's been done as a credit for just incidentally the most westerly point that was mapped and we verified this out here to the West is right near.
R. Scott Harris: The likes there on the border with Alabama so as we look at this a little bit in more detail, we actually.
R. Scott Harris: really want to focus on that that the evidence of the shop there in the courts today, but we also will will say that we also have other defamation, that is seen in the vicinity of that we're looking at to for reference here, this is what some people refer to as the cove here.
R. Scott Harris: And at the border merryweather and talbot and ups and counties long flint river gorgeous of the lamp.
R. Scott Harris: But as we've looked in some of these other ridges extending out from this, we find that the actual the realm of the cove itself we don't find any evidence of shock.
R. Scott Harris: But we come wondering amount and we actually have shatter cones and i'm going to show you those and then the next raid jail, we have what.
R. Scott Harris: Are documented from other large and back structures, like Rita for it, we have what are called shatter cleavages.
R. Scott Harris: That are these are not growth steps or anything like this, you actually go inside of these, and these really then become planar fractures.
R. Scott Harris: That are crossing at acute angles it highly acute angles, almost resembling chatter columns in the sales but they're not fully developed cones they're there they're more of a.
R. Scott Harris: 2d surface to 2d surfaces coming together and Just to give you some examples of what happens with known impacts structures with.
R. Scott Harris: With shatter cones in courts I hate sin course court sites they get pretty crummy they don't look like.
R. Scott Harris: The beautiful things you may be used to in limestone like from catlin or somewhere like that they can be very, very coarse and large.
R. Scott Harris: And, but also typically if you go into them particularly near cold surfaces, you find the the planner fracturing.
R. Scott Harris: And the feather features, this is in the same shot regime that the the chatter calls themselves, develop and sometimes you can actually find more strongly developed plan defamation features.
R. Scott Harris: So this may not look like much initially, this is a big chunk of court site that you might see some stations on one side, some of our impact colleagues around the world, with all the Multi multi stride and services.
R. Scott Harris: But if you turn this up in you start to see that there are sort of of of kind of weird sort of circular shapes here.
R. Scott Harris: But then i'm going to give you a better view of the this side of this this rock that are going to kind of come down underneath where the circles are.
R. Scott Harris: And you're going to see combs their columns here straight at combs coming in a number of them listed here.
R. Scott Harris: And when you look at this rock inside we see along some of the fractures the the feather features developed as as you would expect.
R. Scott Harris: So, and just a few more there the Ad with the have those and again, these are in that sort of next level out next readout from the the cove itself and then.
R. Scott Harris: And then we get into the cleavage the shatter cleavages as you go even farther out and that's kind of what you expect, because there is a.
R. Scott Harris: If you think about an object coming in the maximum.
R. Scott Harris: sharp being at the point of contact and then some diminishing away from that but, at the very Center, and this is a sketch from Gordon is empty of Hutton, which is still.
R. Scott Harris: it's a big structure in Canada, but it's still not as big as what we're talking about so it rather than having a central peek here that would have a lot higher degree of shot.
R. Scott Harris: We would have a central pete green and that even brings.
R. Scott Harris: more reason to point out that that where you have deeper material coming up, you often are below the level of sharp attenuation as at the Center so you have a lot of material.
R. Scott Harris: Coming back in an upward and that's a lot of times in very large structures, the last place you look for evidence of shock, is that the particularly eroded central portion.
R. Scott Harris: it's going to be more as you go out and then, particularly in the object itself and in this case, you see some melt.
R. Scott Harris: That is formed here, along with some a lot this brushes and sway video like materials, and that was you may have noticed a lot of times those.
R. Scott Harris: Those lockers brushes its way bites are kind of trapped in the terracing produced by listed faults.
R. Scott Harris: And when we look around this region with these read the circular riches or semi circle rages, we see a number of things that look kind of like list trick faults.
R. Scott Harris: In the on the horizon, and then, when we actually go out in the field, we find that at the along these mini case cases we actually see the airplanes.
R. Scott Harris: here's a curveball plane coming down and then at the base of these we found in a few locations exactly what we see here at houghton where we have material that looks like a very, very laminated.
R. Scott Harris: flow like material that has a lot of things that look like we're so examining these it looked like they could have been altered glassy materials.
R. Scott Harris: And also courts that has some indication of shock we're actually just recently found this location, with a beautiful brasher of courtside class that are actually seem to have similar affinity to the to the.
R. Scott Harris: The part of the ones with the decorate pdfs in China, Kate itself, but you see, then, a kind of a chaotic clay and mud.
R. Scott Harris: Along with some other type other clays in this section and then looking at some of the player fractures then, and then they are we have those little feather projections coming off of them, so this is exactly what we'd expect.
R. Scott Harris: Another thing that once you have this kind of perspective of this region that you see is, you have the, this is the cove and the distance here.
R. Scott Harris: and linking that that area to the next rage that has the shatter columns are these radio rages that actually are there they're they're actually sink Lionel.
R. Scott Harris: They are maybe only flanks their their client but toward the center's their sink Lionel much in the fashion here that you see these transformational raises that this described.
R. Scott Harris: At large impact structures by Thomas kingman again and his colleagues, so when we look at this entire thing.
R. Scott Harris: We, this is the pattern, we see, and in order to accommodate everything we have to take into consideration the defamation that we see, but also the melt and remember the most distant mill is way out here.
R. Scott Harris: And it turns out, we found even more that's back here this little thing that's mapped as a berdych.
R. Scott Harris: Nice back here actually a grenade nice blocks in a nother China cake that has this little art back here, so if you just try to accommodate that in a cartoon you end up with something like that.
R. Scott Harris: Now we could talk about tectonic modification of something that like that, or you know what portions of it are.
R. Scott Harris: are part of really contain this, but this is going to require tremendous amount of mapping over very large area to very detailed has probably never been done here before.
R. Scott Harris: And I also put that cartoon out so we could compare it to other planets and we see these big elliptical things on other planets like Schiller on the moon or Tara on Mars, and even hail here on Mars and.
R. Scott Harris: This is hail, which also is a similar scale, but what we're looking at this is about 150 kilometers.
R. Scott Harris: In length here and they you see this again media rich and in rather than a central single uplift in this this thing expands almost the entire thing and even it Schiller there.
R. Scott Harris: there's likely that that rage continues, but then was covered by melt or other feel with regular there are lots of.
R. Scott Harris: Discussions about whether or not these are very low angle, in terms of 15 degrees or under or whether they can be somewhat higher angle, but represent bodies that are breaking up, and so you got a series of downrange impacts.
R. Scott Harris: One of the problems in dealing with the models for that on other planets is we don't have these on earth to look at so identifying one here on earth to really to look at in detail, could be extremely important.
R. Scott Harris: And they have to be out there and just to finish up here how old is this well, we would consider the melt then if the mouth is an impact melt than the impact the agent melt is the age of the event.
R. Scott Harris: And old data from the 70s indicated zircons work in the China, Kate coming up with an age of.
R. Scott Harris: round a little more than a billion years old, but stephens gone back and looked at this in more detail.
R. Scott Harris: and found that the youngest zircons actually come in at about 800 million, and so you actually see a suite that likely is crystallized from the male and the inherited suite of 1 billion target.
R. Scott Harris: In here, so we would place that agent about 800 million and that's kind of neat and important because it turns out that just this last summer i'm.
R. Scott Harris: A Japanese group analyzing the data from the moon um I had an HR communications article dealing with their analysis of a number of craters that cluster at an age on the moon of these are large craters including Copernicus.
R. Scott Harris: i'm at about 800 million and they actually predict that, based on that flux on the moon, that we should have there should be enough mass and counting earth during that same time period to have at least two.
R. Scott Harris: chicks loop scale or greater size craters out there on our planet, and so we would suggest that we may have found one of them, and that can be incredibly doubly important because, at the same time i'm a group from MIT looked at analysis of climate models of how to get into snowball Earth.
R. Scott Harris: At you know they're just after 800 million and they actually came to the conclusion that you needed very rapid.
R. Scott Harris: decline and solar installation and so, how do you do that well they suggested volcanic eruptions.
R. Scott Harris: Well, another way of doing that are want one or more impacts, particularly large low angle impacts that could put in a very large amount of debris.
R. Scott Harris: into into the atmosphere, sometimes, sometimes even producing rings around the planet, that would.
R. Scott Harris: For some period of time of debris that would interfere with the solar installation and perhaps trigger that so with that.
R. Scott Harris: i'll say thank you and and a special thanks to you know if I start naming everybody who's contributed to this, I would miss somebody, but I have to mention David himself, along with the Troy raspberry with Stephen up with a stony brook doing their homework and.
R. Scott Harris: And with that I will come back to you.
David King: Thank you Scott um so the peppers open for comments and questions so hope we have some questions from the audience and just unmute your MIC or you could do a chat and then read it to the to the authors.
Julia Cartwright: I can ask the question i'm just to get things started off and have you thought about what type of impact this might have been.
R. Scott Harris: No we're we're a lot we're quite a long way away from from that, I mean this is establishing that you, you have a structure than trying to figure out what you know how big and everything but in terms of getting into.
R. Scott Harris: Analysis exactly what that would be you might have some ideas from the Lunar record what those those could be to perform some of those some of that population on the moon, but even that's.
R. Scott Harris: will be I think fairly speculative at this point.
Steven Jaret: Can I add to that answer Scott.
sure.
Steven Jaret: Something we should point out that we don't even yet have impactor trace element data, so what we're working on PG and but we don't even have that yet so it's a little long way before we can actually even identify it young that.
Steven Jaret: We are working on it, though.
David King: I just encourage you guys to to.
David King: Do the detail mapping that I think the project deserves, and you know this may be a lots of little outcrops that nobody ever really notice, but now that you have a picture in mind.
well.
R. Scott Harris: Thanks to the pandemic we've done quite a bit of field work over the last year and.
R. Scott Harris: that's helped solidify a picture that it had a little stamp pieces it's no longer stamp pieces so now it's a matter of.
R. Scott Harris: of looking at, you know that that bigger picture, with a with very different scale.
Colin Jackson : How much of the shape of the impactor can be modified by tectonic information.
R. Scott Harris: Well, the the the issue with what we have, there is, we have the central portion that doesn't look like it's very modified at all.
R. Scott Harris: We don't have we've got the the different levels of shop where they should be for something that is a bleak and we know that some of the if.
R. Scott Harris: Not to directly answer you, but this is part of this is the, we know that a lot of people who worked in this region law, the tectonic basis.
R. Scott Harris: would say, well, what about all the collisions and everything that we've had, and one of the things about the pine mountain window here is is the recognition from the beginning it's below the appalachian detachment.
R. Scott Harris: And there are a number of structures in Scandinavia that have playing evidence of having having structures that were below different organic attachments that now had been assumed and preserve all it says just say were formed yesterday.
R. Scott Harris: And so that was probably what happened here I I there There probably is more there's some interesting cheers zones and things that are actually over toward all burn and so that's one thing.
R. Scott Harris: You know long range that's going to be interesting to look at how many of those years owns our primary and then how many of them are due to lateral transport along that while ago which that that is a big mesozoic.
R. Scott Harris: lateral fault that has that has taken the northern portion of the structure, whatever that original mentioned away.
David King: Thank you Julia i'm going to hand off to.
Julia Cartwright: All right, well, thank you very much for that Scott.
Julia Cartwright: Our next speaker is one of our chat today, David king and his presentation is entitled creative filling materials when TIM getting back structure Alabama The co authors on the presentation are almost cartoony democracy and I revolve take it away.
David King: Okay, thanks, and I know the videos over the top, so.
David King: You notice so.
David King: This this entire structure.
David King: hails from like rotation, so this is the like rotations world and there was a greenhouse were opened and sea levels are at their vendors or maximum says a lot of real estate underwater including.
David King: The.
David King: hurry of the plains of Alabama.
David King: We don't really know the flight line, this is a possible fly on suggested by.
David King: Perhaps the the shape of the structure but.
David King: It works, but somehow the object comes in, at a reasonably low angle and strikes in the shallow water of the Gulf of Mexico, this is some artwork that city of temecula commissioned some years ago, showing the asteroid coming in.
David King: brightly shining in the sky above the seas covering elmore county, and this is the most a circle it estes and its jaws is the little fish and codecs which we found fossil remains of both of these creatures in the area.
David King: So it strikes in any offshore maybe a few 10s of commuters offshore.
David King: The foreign ball is rising, you see them brownish red material being injected that's based on the coloration of the target tuscaloosa formation.
David King: This little dinosaur appalachia Soros also comes from this area is obviously a little bit stunned about what's going on there, and as walking along the light cretaceous shoreline.
David King: So this is a another view our view.
David King: Of the crater some some years after the event, it would have raised a ring a little archipelago the rim.
David King: Low on the southwest side is, as we notice today.
David King: We found some what we think are old shoreline deposits on the room itself so that's kind of interesting.
David King: We will have been working on this.
David King: crater since 1997 we actually started working on it.
David King: Preparation for the field trip for the SE from GSA meeting, which was held last last time in Alberta in 1997 and my like colleague Tony other he was part of this project.
David King: Including.
David King: lucille and Christian and bill, and so we got to send a.
David King: The proof of impact, we were able to publish.
David King: PDF measurements consistent with with a search retargeting impact one of one of our one three points and the song, this is a shot grain and bill mounted on the head of a needle we also.
David King: got geochemical analyses of the branch from one of the core boxes Christian purple's lab did this for us when we got iridium and chromium nickel, cobalt.
David King: So this is, this is the.
David King: creditor room area in the in the city with tonka lives right along this this us to 31 card or and a little bit of residential area on the West side of the River.
David King: And the impact remnants crystal material that shows the distribution of drill holes that we've accomplished over the years, this is.
David King: I just sort of a cartoon showing relative depths of these drill holes that the deepest one is 715 feet So these are not going to the bottom of the creditor by any means.
David King: some years back, we send some materials over to john Marco at Arizona state, and she did uranium dorian helium dating.
David King: On the structure and it came out a 4.4 million, with a pretty wide plus or minus 1.4 so confirmed our notion that was like cretaceous and kinda was in the ballpark while we were thinking.
David King: In terms of a fizzy graphic math Alabama that's where we attempted sits it's right at the absolute maximum southern limit of Piedmont rocks, this is what.
David King: The creditor looks like can kind of old style and DM that's the coosa river command bends around it and it's the Crystal and Ram.
David King: there's a disturbed terrain out here, and then a creditor filling to Ryan, and the interior, this is a lidar rendering of elmore county this lidar data was provided by the tax assessor county and you can see clearly the.
David King: dvr queue at nature of the structure so there's no no other type of graphic feature know kind of looks at anything like that.
David King: Just sort of sticks out if you go up on the rim on the West and look toward the East, you see this high ground in the Center but also there's the there's the distant Eastern rem.
David King: there's a little notch in the trees, there were a pipeline because cross the eastern them.
David King: So you're standing up here on the western room, this is from the Center looking along that pipeline across the Florida crater and there's that them on the eastern side, and this is from a low flying aircraft looking toward the south, see the crowd around and that's us to 31.
David King: That comes up from Montgomery it actually runs up on the rim in that area, this is just north of the commercial corridor, as a group of antennas that are situated on the high point on the remnants gumball nom.
David King: And it's taking advantage of the elevation there for the local communications network there the stick pen or Alabama is where the creditor is located in Alabama so just but 1012 miles north of downtown we go me.
David King: Back in the day, the appalachian mountains for more steeped in they are now verse and I came down there was a coastal plain area.
David King: Dennis was shall asked for this is middle shelf, you can still see the middle shelf chalks That said, white swath and you guys still seeing the satellite photos that's that's the chalks the middle shelf that are weathering out there.
David King: there's the.
David King: crater and Google earth there's the rem which is hard Christian rock is a crater floor of silence and.
David King: Then there's a disturbed area that's has a number of faults, which are dipping toward the structure itself.
David King: that are related to the crater this area faults is similar to the to the annual ring around Chesapeake Bay it just sits right here, instead of going all the way around the crater structure we only see it now here.
David King: Always I was wondering why you know the credit for women relating with cemetery target that should have been blown away but it turns out that.
David King: Because this is a marine impact and because we think the southern ren was made my sentiments they slip back into the creditors so i'll show you in a minute how we think that work.
David King: So now crops here and the River behind the Bank and waffle house, you can see the validation in the room, this is a city courthouse, and these are.
David King: places where you can see that Kristen material, the city is gone big on this and runs annual crater tours i've placed.
David King: Nine of these interpretive signs around the area, this is the one behind the Community bank shows where it is immaterial as little text there, so people can take a self guided tour on the crater floor we see these kinds of reddish sandy sediments it's this is mainly to tuscaloosa formation.
David King: which was a target unit, but also there's utah formation and volunteer.
David King: A lot of times these sentiments are sort of mixed and blended sometimes they're actually folded you can see, falls in here.
David King: A hot those huge just a minute, so we think that this southern part of the room was actually softer sedimentary material in large part, or is the rest of it around was more kristin maternal.
David King: Because the room is deeply Ronan so we don't know for sure what it was exactly like know anything that that southern room slid and we can see.
David King: upside down strategic griffey as part of this flow can see tuscaloosa on top of utah, which is an agent version probably from the flat structure that proposes run, so I call this a translator slide this actually was the ends are most inventive term for more what we see here.
David King: And so we can see sometimes these steeply inclined large blocks, or we can see these folded layers that are part of this transmitter slide.
David King: One of my students was working.
David King: There, just a few years ago, we had the county come out and scraped off some of the material in the Center.
David King: We uncover this boulder breteau which has a shocker ions in it, as well as some accretionary locally, but she discovered in this red matrix also.
David King: These large blocks were uncovered you can see the foley ation these are metamorphic rock blocks see you see the full Asian their.
David King: Membership rocks tend to break largely paralleled affiliations, so this being 15 meters, there was a much larger dimension of it in the other way and if you look at blasted.
David King: metamorphic rocks inquiry's usually it's like a two to three ratio the dimension of blocks would actually think these blocks are huge and they were like 45 meters, perhaps.
David King: We only see the little window of the outcrop and we see the Block one that sound, but, but if you think about the way the metamorphic rocks break parallel differentiation that much longer than one direction or another right so.
David King: Anyway, we find out those scattered in in the interior, as some sort of.
David King: rejected deposit that slipped back into the crater we also find these tsunami deposits in various places and the chocolate is not being deposited in this area is too close to shore, but the sauna tsunami wave we think brought these talks back.
David King: They form graded bed deposits we've drilled.
David King: 27 meters of of chalk here and there's several meters here and the subdivision over here.
David King: Challenges is not just everywhere, we think it filled in some of the low places and other places it's just not there.
David King: And so we think that return of display seawater and we do not know the extent of return display seawater and i've gone much further inland and this.
David King: This there's some notion of what it might have been like so.
David King: So in analyzing the strutting griffey of the creditor filling.
David King: From boreholes and outcrops and saw we know there's a deeper sand phil call this the impact, I can see it.
David King: In some of the outcrops in some of the deep more deeply eroded places where the streams.
David King: So then there's around failure, and we have the transcript or slides, so the transcript or slides sits on top of this, deeper impact filling say.
David King: Then that boulder branches slides in its its proximal object, it has those giant box, as well as time you shocked cranes and other materials.
David King: And so it slides in we're not sure exactly where on there and it comes from, but it feels part of the quarter and then the tsunami comes back so that's the sequence of events and the strata graphic sequence of the crater filling.
David King: You can't go to one place in the crater and see that whole sequence, you have to go around and but we've been able to piece together that's that sequence so.
David King: we're tonka has has benefited from.
David King: A lot of different sources of funding over the years, like I said we've been been working there for more than 25 years.
David King: And these are some of the entities that have given us funding over the years, also the landowners, been very kind to us to let us go on their property and we develop trust with some land owners who.
David King: Otherwise they're not really all that receptive to to outsiders trumping in their backyards and some i'm also want to say a word about Tony other uh he was wonderful.
David King: Challenges gentlemen um I was very privileged to know him and he's actually the one who back in the late 70s suggested that this probably was an impact crater when he was working for the geological survey and passed by a few years ago, but he was he was instrumental in.
David King: getting us the funding to do those drills things that that were key to that he psl papering so.
David King: sorely missed also wanted to be acknowledged the contribution of ian's hormones work with us since 2003 on the crater has been here most most years visiting and doing fieldwork and.
David King: My dear colleague at auburn with sale and also Christian curbed la emailed us and then in the initial phases and they'll homes and others, more recently, our work has turned to.
David King: modeling that impacts and the next talk is by a student who I supervise with my colleague in aerospace but on my wall her name is teacher to marketing and she's going to talk in the next Piper on the.
David King: So modeling, and so this sets the stage for that, and then the second question to be happy to to try to address them.
Julia Cartwright: All right, great Thank you David and we certainly have some time for questions, and so, if anyone has any questions, please feel free to either unmute your MIC or and also a question raise your hand.
Julia Cartwright: Using the reactions in the zoom portal.
Julia Cartwright: or write something in the chat box.
Julia Cartwright: I guess I can ask if there's been any advances in locating melt sheets for winter.
David King: melt is is elusive.
David King: We have some materials that we think may have been melted but they have long since.
David King: become clay and.
David King: So when you when you see that and then section you you wonder well is that really does that a melt or is that just the clay bomb.
David King: So I wish we did him out I.
David King: it's my understanding from the survey of the literature that melt is relatively rare in marine impacts and you wouldn't think that because you would think that the presence of water might.
David King: assist in melting materials, but it seems to be kind of the other way around, just in general but.
David King: The search for the milk goes on and.
David King: i've just briefly mentioned those accretionary locally, that my student found in that branch unit in the centers of those the little core to me looks like a melt texture but they're very tiny and.
David King: I don't know that.
David King: My colleague go hames actually agrees with me about that, but that can be the closest thing to mouth and we have those cores of those little appealing to the search goes on, I wish I could say we did have classes, but.
David King: But we need you know.
David King: pdfs feather features yeah we've got those.
David King: Know shatter counts, I don't think the material is.
David King: The crystal energy is not quite right for that.
David King: At least not clear.
David King: Examples i'm saying.
Julia Cartwright: Well here's a here's a follow up, I guess, I.
Julia Cartwright: Could you talk about when TIM care in the context of the impact crater potential that Scott Harris talked about and his previous presentation.
Julia Cartwright: Because there are not that like geographically there potentially quite close and age wise I think he said 1 billion years was how those are fun.
R. Scott Harris: hundred million.
Julia Cartwright: Oh sorry ya know that complete different sorry I got my.
Julia Cartwright: Sorry.
well.
David King: I don't see a relationship there and turn but I essentially thought you know.
David King: Every good every southern state deserves an MPEG crater.
Julia Cartwright: Well, let this thing.
David King: For you trying to to to unravel kill Michael and Mississippi for years and.
David King: i've been dobroshi creek and Louisiana and that's you know, maybe someday.
David King: scott's on the trail of the Georgia.
David King: Where all your phone and.
R. Scott Harris: i'm being you notice the evidence is forcing me to share one with you.
David King: So you have one and.
David King: Just.
David King: yeah okay.
Julia Cartwright: As long as it's a Community effort and that's fine.
David King: So.
R. Scott Harris: Julia if I might just you know a lot David dried about the Marine impacts not yet the dynamics of those not necessarily generating a lot of milk.
R. Scott Harris: But most of that metal is generated in the agenda, and so, those are of us around the southeast both to the east end of the West need to look carefully at our cretaceous tredegar fee for that material.
David King: Yes, now that we know the age.
David King: And I.
David King: I believe in central Alabama that that age Dave is very close to the utah mobile contact.
David King: But talk about waiting for an answer.
Julia Cartwright: Okay, well, we can we can continue this conversation a little bit later, I would like to move us on to our next presentation, just to keep things going, and so our next talk.
Julia Cartwright: is entitled.
Julia Cartwright: A numerical analysis of the winter i'm getting back crater with focus on the southern collapse during the authors are.
Julia Cartwright: apologies if I pronounced incorrectly.
Julia Cartwright: Democracy agarwal King amo and the presentation is being given by the pizza the mochi yes that's great okay great.
Julia Cartwright: Thank you so much.
Leticia De Marchi: Well i'm leticia the Marquis i'm a PhD student at auburn university so Dr king is my advisor.
Leticia De Marchi: And today, I will be presenting my work with an American experimental analysis of the with tempo crater, it is very nice to present.
Leticia De Marchi: The modeling results, right after this very detailed presentation on with them because geology, so I will try to not be repetitive and i'll try to make it simple, so you don't have to listen everything again about that with them because geology but.
Leticia De Marchi: Just okay so with tonka as Dr King just said is a 7.6 kilometre simple crater located in central Alabama formed around 85 million years ago during the late cretaceous in a shallow see environment.
Leticia De Marchi: The water depths at the time of the impact is interpreted to be in between 35 in 100 meters.
Leticia De Marchi: And the target were was comprised from bottom to top of crystal in raw from the Piedmont metamorphic terrain, and this was overlaid by sediments from the upper cretaceous specifically tuscaloosa group in utah information.
Leticia De Marchi: So as Dr King just showed the crater was extensively drilled it has a good detail geologic characterization again the same figure here this finger on the right, shows the location of this drill course.
Leticia De Marchi: So with tonka it's not like most of the other creators, it has some unique features.
Leticia De Marchi: such as the horseshoe shaped outline in this again this happened because of the Southwestern section of the rain collapsed into the crater for me what we call the transcribers lie, which is one of the creator few units.
Leticia De Marchi: The main objectives of my work is to gain a better understanding of the formation of marine target creators, in general, but focusing on with TIM come.
Leticia De Marchi: To understand the placement of the creator few units into detail the effect of different impact scenarios zinc back conditions such as velocity.
Leticia De Marchi: Water depth and settlement thickness how this will affect the development in final morphology of the structure and finally to compare the geological observations with the the model results and the experimental data.
Leticia De Marchi: So, from a drill course third is we, we know that the crater few can be divided into different units so from bottom to top we have the impact i'd sand, which is a mixture of sediment Tara target rocks.
Leticia De Marchi: Then we have the transcribers lived formed by the collapse dream, then the boulder bread chef formed wise limbo for up fragments from the rooms, and this was the unit were shocked parts were identified.
Leticia De Marchi: and on top of everything we have the research, the bosses formed by the returning seawater of course there's, this is a very simple.
Leticia De Marchi: illustration showing more the sequence of events or the order of placement of the cemetery units, but the actual scenario looks a little bit more complicated than that.
Leticia De Marchi: So it looks like this So here we have the impact i'd send unit transcribers live the boulder branch in the research deposit.
Leticia De Marchi: One thing to note here, and then we have the drill course so one thing to note here is that the drum corps do not reach.
Leticia De Marchi: The bottom of the crater so the creator floor, but we know from a gravity analysis that we have a higher density layer close to the crater floor, and this is limited by this dotted yellow line here so everything below this line has a higher density and above this line has a lower density.
Leticia De Marchi: Also, one of the drill cars in the crater field located close to the eastern room, it shows an inverted stratego fee of the target, so this suggests that there's materials learned from the overturned rim flap.
Leticia De Marchi: So the Tampa formation is being stimulated by I sale to D, we ran a total of 12 simulations varying the impact speed.
Leticia De Marchi: The settlement thickness and the water depth, so we did different combinations of this input parameters are best fit model cause considers any factor of 400 meters in diameter.
Leticia De Marchi: In a grenade in factor in this is traveling at 12 kilometers per second, we also have a three layer target comprised of the crystal in basement 200 meters of what sediments and then the seawater layer with about 60 meters depths.
Leticia De Marchi: So all for each material, we used an a specific equation of State, so this equation relates, the pressure to the density and internal energy of each material under the impact conditions, so we used.
Leticia De Marchi: Granted equation for the christening basement what for the wet settlement layer in granted for the factor as well and water for water.
Leticia De Marchi: We use the damage model that accounts for station a share in the materials callings damage model, so it accounts for sheer intake in the material.
Leticia De Marchi: And the simulations were performed at 32 cpr which means sales for projectile radios and this results in a cell size.
Leticia De Marchi: of six point 25 meters so everything that is smaller than that it's the simulation is not very reliable for everything that is smaller than six point 25 meters any features smaller than that.
Leticia De Marchi: And in order to get more realistic values for the simulations I specifically target material.
Leticia De Marchi: parameters, we collected samples from crystal in room and we prepared the samples and submitted to two different types of mechanical tests.
Leticia De Marchi: They were the splitting textile test here on the left, also called Brazilian test the give us the thing style strength of the material and the unique so impressive test that give us the impressive strength of the of the samples.
Leticia De Marchi: These are the results of this bleeding textile test, so we have this stress versus extension curves for each specimen.
Leticia De Marchi: Here in the right, we can see how the stress was applied a relation to sample orientation in relation to the fully ation and that's how we calculated the day cycle strengths, we got an average of 9.7 for seven mega festivals.
Leticia De Marchi: Now, these are the results of the unique so, can you next okay impressive test, so I have this stress versus strain curves here on this graph again on the ride how the stress was applied in relation to the affiliation and how it was calculated, so we got an average of.
Leticia De Marchi: So now, with this tool calculated values for impressive and inside of strength we were able to estimate cohesion in friction angle.
Leticia De Marchi: By using these two equations here, cohesion and friction angle, based on things silent impressive strengths so on the left with we look at the more circle, we can see the calculated compressing strength.
Leticia De Marchi: That they saw strength and then the estimated friction angle value and the estimated cohesion so.
Leticia De Marchi: Using this calculated and estimated values, we were able to set the input parameters for our simulation in our simulation looks like this.
Leticia De Marchi: On the left, we have a lot of different types of materials or sea water, the sentiment layer and the crystal in basement.
Leticia De Marchi: And on the right, we have a flood of damage, so far, what we can see as the creator opening the room flat formation tsunami formation and propagation.
Leticia De Marchi: And then we start to see the beginning of a downward movement of material from the reams first Kristalina material, followed by cemetery material.
Leticia De Marchi: These are some key timestamps overstimulation so we have two seconds, here we can see the early excavation stage at 14 seconds, we have a maximum opening of the Creator, so that makes me crazy and creator and.
Leticia De Marchi: At 28 seconds, we have formation of the room flap and, consequently, the tsunami waves that propagates and, if we look at the last time step here in the lower right at about 175 seconds, this is the time step, where we start to observe.
Leticia De Marchi: A downward movement of material from the rooms in this is reassured by this finger here this inset figures showing the blood of velocity on the X direction.
Leticia De Marchi: So everything that is in red here indicates a negative velocity so things moving to the left so moving towards the Center of the Creator, so we have material from like crater will and removing towards the senior of the Creator.
Leticia De Marchi: This graph shows a lot of pressure by depths near the Center of the crater so we have four different bullets here from point one second 2.4 seconds in we got.
Leticia De Marchi: Max of pressure big of 42 gigabyte baskets at point one second This is illustrated on this by this figure on the right, where we have a lot of pressure at point one seven.
Leticia De Marchi: And this pressure big of 42 giga pascal's is compatible with planner defamation features that were identified in with them, so this.
Leticia De Marchi: pdfs are they have an a specific interval of pressure that they are formed, and this is compatible with the pressure peak that we found.
Leticia De Marchi: In our models on the right here, you see, like a microscopic fig photograph of this pdfs and the frequency and orientation of these pdfs in relation to the cx is of the courts Greens.
Leticia De Marchi: Going back to the stable year our pressure big of 42 gigabyte Pascal so we would also.
Leticia De Marchi: It could be also possible to find this dish of our core side which are courts falling morphs but so far they were not identified in with tempo.
Leticia De Marchi: So as a summary of the main findings, so far, the the creator for sequencing the model is consistent with the gravity analysis that predicts that higher density layer close to the the crater floor, so this is.
Leticia De Marchi: We can see this in the model by looking at the first crystal in materials lighting towards the Center of the crater, so this is compatible with the gravity analysis.
Leticia De Marchi: The pressure at the first stance of seconds are compatible with the pdfs that were described in drill course in in the model, the crater room, we can see that it's mostly composed of centimeter material so you're linking this model to the Southwestern section of the room.
Leticia De Marchi: And the collapse of the the ream.
Leticia De Marchi: In the model is reassured by geological observations to drew core observations, for instance, that.
Leticia De Marchi: inverted stratego fee that was observed within the transcribers like Union.
Leticia De Marchi: As future work we are planning to analyze the interaction between the returning to water with the crater rooms by modeling.
Leticia De Marchi: This the fluid mechanics of this like returning seawater to see how is the interaction of how this effect during collapse also we want to.
Leticia De Marchi: go deeper in the effects of the material and his alter P, like the fully ation in order characteristics in with them krista target and for this project there's also an upcoming experimental campaign at the Spanish astrobiology Center with Dr as formal.
Leticia De Marchi: dessert my acknowledgments we're very thankful to the developers of ICO to the island project that is going to make the experimental campaign possible auburn.
Leticia De Marchi: Funding support NASA astrobiology support and, of course, to deal with them land owners that always always give us a green light for fieldwork.
Leticia De Marchi: that's it will be happy to take any questions.
Julia Cartwright: Great Thank you so much Lisa.
Julia Cartwright: Do you have any questions for leticia.
Julia Cartwright: Well, I can I can ask a couple and one question I have is and does your model incorporate.
Julia Cartwright: Impact angle.
Leticia De Marchi: It is so this we use ICO to D, so we are not able to do the simulation considering a specific angle of impact so we're simulating a vertical company.
Leticia De Marchi: So 12 kilometers per second would be the vertical component of 16 kilometers per second at 45 degrees angle.
David King: You might.
David King: Just tell.
David King: People hear.
David King: About.
David King: How many different kinds of model runs you did, and what should I experimented with because some people might think that will you just put the numbers and push a button and it was all done it actually took you.
David King: many months to do this, maybe you can do them idea of how long it takes to do these rounds.
Leticia De Marchi: Yes, so this simulations are running for at least like eight months it's a very slow process, it requires a lot of like computer power in so we started to do the simulations in 2018 so total I have more than hundred simulations so as we.
Leticia De Marchi: gain more understanding about the creator and the input parameters, we we change this input parameters, we improve or simulations but the last.
Leticia De Marchi: group of simulations that were set to run, we had a total of 12 simulations so this last part where we improved some other input parameters improve their understanding, I mean in.
Leticia De Marchi: We played around with a settlement thickness equations of state used to represent a set of also velocity we did 20 kilometers per second in.
Leticia De Marchi: 12 and we also did a different water depth scenarios so mile 125 meters and 60 meters approximately so by like combining this different bear meters, we can have like.
Leticia De Marchi: A huge number of simulations so then we compare the diameter, the depths in things that we can compare with the field work observations in try to find a best fit model.
David King: home how long do you think it will be before the water comes back, I know that could never comes back in the simulation was do you have any ideas.
Leticia De Marchi: So, like a month, those are seconds.
David King: seconds more than 200 right.
Leticia De Marchi: Yes, yes it's about like 600 seconds yeah depending on the simulation, of course, but we ran we ran some lower resolution simulations also that we could see like a big picture of.
Leticia De Marchi: What we should expect to happen all the processes that we would expect to happen to see in the model in this lower simulation resume this lower resolution simulations show that the water comes back at.
Leticia De Marchi: An average 600 seconds.
Colin Jackson : I had a question regarding the the production of impact mill.
Colin Jackson : is permanently yes from the previous presentation, because wondering if there was impact melt still contained within the geologic record but made from your presentation, it seemed like perhaps the event was maybe.
Colin Jackson : On the borderline of being energetic enough to produce the voluminous impact note, can you discus me and maybe what the uncertainty is regarding the whole energy and whether that would would would be sufficient to produce enough melt w might expect to find it in the record.
Leticia De Marchi: Okay Oh, first, I think, like the fact that melt.
Leticia De Marchi: fragments we're not identified.
Leticia De Marchi: In with TIM cook doesn't mean.
Leticia De Marchi: there's no male, but they were not identified so far and.
Leticia De Marchi: So of course there is there's some like uncertainties related to the model.
Leticia De Marchi: it's not like exactly 42 gigabytes coast, so we try to validate the model by comparing with what we have, so we know that this 42 gigabyte skulls make sense, considering like the PDF occurrence.
Leticia De Marchi: And maybe we would need to slowly compare with geological observations to see how reliable, the motto is in if we look here the pressures required for impact melt.
Leticia De Marchi: It would be a little higher than what we have in the model i'm not saying that the model is hundred percent right, but so far we have some things that reassure the model.
Leticia De Marchi: Results like pdfs in like the inverted stratego fee and the layer of higher density in the bottle close to the bottle some features like this.
Leticia De Marchi: Did I answer.
Colin Jackson : yeah great Thank you very much.
Julia Cartwright: All right, well, I think we have to move on to our next talk, so thank you for that and our next talk is actually a pre recorded talk so once I fat around with my screen little bit i'm just gonna put that out there.
Julia Cartwright: Hopefully you can all see this um so our next talk is entitled meet crater ejector distribution of ejector derived Roi on Venus so moving to a different plans your body now, which is fairly exciting the.
Julia Cartwright: authors of this presentation or Jennifer when Bruce Campbell and the position is given by.
Julia Cartwright: Jennifer women.
Okay.
Julia Cartwright: hello, and welcome my name is Jenny Witten and i'll be talking to you about a lot of the recent research i've been doing, looking at the distribution of crater ejecta across the surface and Venus.
Julia Cartwright: like to start with a view of Venus because it is so very distinct from earth probably one of the more notable things is that Venus appears right in the sky, because it has a very thick.
Julia Cartwright: atmosphere that obscures the surface from view at least at the visible wavelengths so in order to get a view of the surface, we have two options.
Julia Cartwright: The first is to send landers to Venus and the second is to peer through the clouds wavelength longer than the visible wavelength, and will first explore that lander view of Venus.
Julia Cartwright: The Soviet Union had a Venus program in the 60s throughout the 1980s they've been there and they go landers were deployed and landed on Venus between 1961 and 1984.
Julia Cartwright: You can see the distribution of their landing sites and the slide here with most of them hovering around the Ecuadorian region of Venus.
Julia Cartwright: These lenders go from benares seven and the mock up of what benares seven looks like is shown on the bottom left of the slide.
Julia Cartwright: All the way to veneer of 14 and then through veil one and two.
Julia Cartwright: And on the bottom right i'm showing a mock up view of the veneer and I lender and you can see how much more complex this system became over time and one of the great additions to these later landers is a visible camera.
Julia Cartwright: So on the right hand side here we're seeing the series of panoramas that were collected by these landers in the 70s and 80s.
Julia Cartwright: And Vanessa nine and 10 each had one camera so we get one sort of front facing view from the spacecraft whereas 13 and 14 had cameras on both sides of the spacecraft so we get more of a 360 degree view of the landing site.
Julia Cartwright: And thinking back to the question of regolith these these images are quite striking because we don't see very much regolith on the surface, this is in stark contrast to what we see on Mars to what we see on the moon and mercury even.
Julia Cartwright: There doesn't appear to be much fine grain material on Venus that's especially true if we take a look here at the naira 14 that appears to be mostly cloudy rock at the surface, but we do begin to see a little bit more sediment and then nine through 13 and panoramas.
Julia Cartwright: In the early 90s NASA sent them Magellan mission to Venus and that mission was equipped with a radar instrument, and so we were able to image that 98% of the service of Venus.
Julia Cartwright: Had a wavelength of about 12.6 centimeters and that wavelength facilitated imaging of the surface and during that mission there was a hunt for alien land forms looking to see you know where is the sentiment on Venus.
Julia Cartwright: This map here is showing the distribution of various alien land forms that have been identified in the.
Julia Cartwright: blue boxes are fields of wind streaks and those wind streets what they look like are shown in the bottom left image that just popped up.
Julia Cartwright: You can see that are there are several win streak fields across the surface.
Julia Cartwright: And addition to win streaks variety of doing fields and putative yardage field were identified in yellow boxes here the.
Julia Cartwright: yellow box i'm showing in particular, this is the putative yard and fields where you can see in this image, the.
Julia Cartwright: linear curve a linear black lines are interpreted as yearnings.
Julia Cartwright: The other yellow boxes show dune fields and micro June fields across the surface and, hopefully, if everything else on this slide The one thing that is really standing out are these parabolas shaped land forms are covering a large fraction of the surface.
Julia Cartwright: we've been able to identify around 60 of them on Venus they are as the name implies parabolic shaped features they're all opening towards the West.
Julia Cartwright: And these parabolas can depending on the source creator size can extend up to 2000 kilometers away from the source impact crater.
Julia Cartwright: And their interpreted to be composed a fine grain impact ejecta that is lofted into the atmosphere during an impact event.
Julia Cartwright: And carried by east, west zonal winds westward and slowly that material rains out of the atmosphere forming these parabolic shapes on the surface.
Julia Cartwright: This is an image from Magellan that shows the distribution of the 60 land forms that we can currently observe today.
Julia Cartwright: There are only 1000 craters on Venus, and so the map you saw before, and this map i'm popping up right now shows the distribution or the predicted distribution of ejecta materials for all impact craters on Venus.
Julia Cartwright: The bottom left image here is a view from Bassi crater in the Magellan data and fantasy is indicated by this white dot here.
Julia Cartwright: The parabolic injected deposits are these darker parabola shaped materials that again open towards the West So these are the fine grain materials that were observing on Venus.
Julia Cartwright: And the question I have is where is all the sentiments, especially if we predict a large fraction of the surface, to be covered with crater objective they don't really see it so again, where did it all, though.
Julia Cartwright: We do know, from some recent studies using earth based radar data from the arecibo telescope that there are fine grain materials that has been identified in a unit, known as tester a.
Julia Cartwright: tester a are highly deformed materials that are analogous to earth continents there's been a lot of discussion recently about them being a highly solicit there's a lot of interest in testing.
Julia Cartwright: If we look at the image on the right hand side of the slide on the top, we see a Magellan image of alpha Reggio which is composed largely of tests array and you can see, they have a relative we write radar signature and we see Stewart crater.
Julia Cartwright: Very close to the apex of this parabola here the start material, this is the view from Magellan if we take a look at this bottom image, this is the view from our earth based radar data and hopefully what you'll see our.
Julia Cartwright: Differences in the test rob, in particular, the difference noted by this orange line which is showing significant darkening in the eastern side of alpha Reggio.
Julia Cartwright: With the earth based data were able to collect different polarization.
Julia Cartwright: which give us different information about surface roughness from different links skills from meters to hundreds of meters over the centimeter to deciliter scales so that's the advantage of the earth be 3D data, but it doesn't have the resolution that we have with Magellan.
Julia Cartwright: And so it's from other reasons studies have identified these fine grain parabolic ejecta deposits.
Julia Cartwright: In TESTA in the Magellan data sets and here's just to example showing that tests or materials is highly deformed materials can contain fine grained segment and appeared to preserve that sentiment longer than it is preserved on the low lying planes surrounding these tests during deposits.
Julia Cartwright: So my question evolves from where is the sediment to how much sediment is in the test Ray and how long does that sediment persist in the test right.
Julia Cartwright: So now to meet crater.
Julia Cartwright: The crater is 280 kilometers in diameter and this to me, is just a spectacular view of this crater.
Julia Cartwright: But before I get into too much detail about me I do want to take a quick little radar break I know not everybody spends as much time as I do, looking at the radar data, so I want to make sure we're all interpreting it in the same way.
Julia Cartwright: So in read our data, we are looking at changes in roughness when we look at a smooth surface it tends to be dark and that shone through the this illustration here.
Julia Cartwright: Where with radar data we're sending energy towards the surface and if we have a flat surface that energy bounces off of the surface, as though it were mirror like and most of that energy ends up traveling away from our sensor.
Julia Cartwright: Because we have no energy returning to our sensor that surface tends to appear dark.
Julia Cartwright: On the other hand, if we have a relatively rough surface there's a lot more facets.
Julia Cartwright: For that energy to bounce off of and a higher probability that some of that energy will return to our spacecraft and because we have energy returning to the spacecraft we're going to have a surface that appears relatively brighter.
Julia Cartwright: So back to me crater as I was saying, need crater is the largest impact crater on Venus That also implies that it is the oldest or one of the oldest impact craters on Venus and we can see that need contains.
Julia Cartwright: variations and its surface roughness were in the Center we have a much rougher crater floor than we do in this outer ring.
Julia Cartwright: shown right here there's a combination of relatively smooth materials and highly refined materials, this is the creator and it's near crater ejecta and any impact melt associated with the crater.
Julia Cartwright: But i'm interested more in the distal crater attract So how do I map distal crater ejecta across the surface of Venus.
Julia Cartwright: The way I go about mapping, the distribution of sediment is by looking at rightness variations and some of them are very subtle and they are quantified as backscatter co efficient, but again, that is.
Julia Cartwright: A way of saying radar brightness and mapping the radar brightness of the test raw materials so on the left hand side of the slide I wanted to show a close up of tesla materials.
Julia Cartwright: Each one of these white lines for the most part, represents a rich press, and so we are mapping the slopes of these ridges to identify where set of it may be depositing.
Julia Cartwright: We do this by mapping, the rich slope that is facing away from our sensor, and the reason is shown here in this diagram on the left side of the slide.
Julia Cartwright: When we have energy that is coming from the Left towards the right if we have a slope that is facing our sensor that slope will become saturated and we won't be able to glean any useful information from it.
Julia Cartwright: However, on the back slopes those surfaces are not saturated with energy and so we can make out subtle variations and their radar brightness values.
Julia Cartwright: So on the right hand side, this is an example of the type of mapping, that we do, and in this diagram is showing how we map the back slips so we take this information and analyze the surface brightness variations associated with me crater.
Julia Cartwright: here's a regional view of meat crater just denoted by the Red star in this slide i've also noted along the red line here.
Julia Cartwright: This is the predicted parabolic ejecta extent, based on the size of the crater.
Julia Cartwright: And again, we don't have any indication that there's fine green material associated with need.
Julia Cartwright: In the low line flames so we're going to check in the tester out which are noted in yellow on this diagram to see if there's any indication of impact objective.
Julia Cartwright: associated with the crater and we started our study by mapping out the brightness variations and the tester and the northern portion of this diagram and so that's a little show on the next slide here.
Julia Cartwright: And the graph on the right hand side that is backscatter coefficient on the y axis and again that backscatter coefficient is a proxy for radar greatness.
Julia Cartwright: If we have low backscatter coefficient That means there are surfaces are going to be darker we have a great surface it's going to have a higher backscatter coefficient.
Julia Cartwright: That on the X axis, we have materials that are close to the crater on the left hand side and we're moving further and further away from the crater as you go up towards the right in this graph.
Julia Cartwright: What we can see is that our trend is pretty flat, so there are no obvious changes with distance.
Julia Cartwright: Given what we know about the distribution of the fine grained materials associated with parabolic injected a positive mood expect a trend.
Julia Cartwright: that's more positive where you have a lot more material close to the crater rim.
Julia Cartwright: That falls out of the atmosphere quite rapidly filling in Tokyo graphic roughness so that you end up with a slightly smoother surface.
Julia Cartwright: And as you move away from the crater Ram you have less and less material available to rain out of the atmosphere and so you have less material to smooth surfaces therefore they're appearing refer, which is what we see in Bassi crater is just as an example on the left hand side here.
Julia Cartwright: something interesting to note is that we do see some sort of trend in the trip tessa that are closest.
Julia Cartwright: To me, and some indication of of this positive slope, but as we move further and further away from need it definitely flattens out.
Julia Cartwright: One in possibility for why we see what we're seeing is that, again we really focused on mapping the northern materials and the most early extensive northern materials are on the eastern side of the crater rim, which is predicted to get far less impact ejecta.
Julia Cartwright: We are hoping to very soon, complete the mapping of the tests are in the bottom to assess whether this trend is real and supported by the variations that we observed in the test or on the bottom portion of the slide.
Julia Cartwright: So to summarize the distal objective from the largest crater on Venus which is called me crater is not preserve and surrounding tesla as best we can tell currently.
Julia Cartwright: And so what this would indicate is that the sentiment is not preserved in the tesla for hundreds of millions of years that can be seen, after 10s of millions of years, so we have least some backstop.
Julia Cartwright: suggesting how long these materials survive in tesla, we know that they don't extend for much longer than 35 million years on the line planes, but we haven't been able to identify constraints, for the test or just yet.
Julia Cartwright: and probably the best news is that the tesla are likely not saturated with sentiment, which is great because NASA is.
Julia Cartwright: Hoping or i'm hoping NASA likes one of these discovery missions to Venus whose ultimate goals are to understand the composition and rock type of the tester and if these are.
Julia Cartwright: covered with sediment from impact craters that would obscure the composition of that material, we would just get the composition of the sentiment.
Julia Cartwright: So that's very important for furthering our understanding, but it does still leave the question of where is all of a sudden.
Julia Cartwright: there's plenty of other places to look and i'll be continuing to analyze the sentiment around.
Julia Cartwright: need, as well as other areas across the surface i'd like to just leave this slide up here, I apologize for not being able to give my talk in person.
Julia Cartwright: I am teaching class right now, so my my talk Time started at exactly the same time that's my class So if you have any questions, please feel free to email me at J Witten one@tulane.edu thanks so much.
Julia Cartwright: Right stuff well, thank you Jennifer for her feel great talk and I don't if you have any questions on this theme, or whether anybody would like to start a discussion about thinking about.
Julia Cartwright: Creating on Venus I can say it's certainly something that i'm really interested in, given that I i'm thinking about impact cratering on asteroid so looking at other financial bodies is awesome.
Julia Cartwright: So yeah if anyone has any questions feel free to to either say them out loud raise your hand or pop something in the chat box and I will say that we're coming up to a break, right now, which, in the UK, we would call tea time, so we tend to go get a cup of tea.
Julia Cartwright: or equivalent maybe coffee over here so um, I guess, I could encourage attendees if they wish to have a discussion right now and that might work or, if you want to go and.
Julia Cartwright: grab something to drink or use the restrooms or whatnot That would be a good time to do that, to their calling and David have anything else to add.
David King: No.
David King: break and.
David King: Come back.
Julia Cartwright: In 15 minutes you got 15 minutes go.
David King: Well i'm.
David King: From Atlanta and i'll be your.
David King: host yes.
Great.
Julia Cartwright: Okay well i'm definitely going to go and get them to.
David King: drink and maybe use it sees myself, so I will go and switch my video off okay.
Julia Cartwright: we'll be back soon guys and 15 minutes.
Pedro Montalvo: Are you able to see the site.
David King: There we're getting.
David King: Some of an introduce you because it's it's actually into your time now so.
David King: speakers.
David King: Pedro Montalvo who is.
David King: A doctoral student at altering and.
David King: he's being supervised by masatoshi here and by she in her space and myself and he's going to talk about contributions of impact mixing to the special distribution of water ice and some currently shattered southern polar craters on the moon so what's your go ahead, thanks.
Pedro Montalvo: Alright, thanks for the introduction and for those who don't know me i'm fed on tenable, and today I would like to share the results from part of my research dissertation.
Pedro Montalvo: which says how impact mixing plays a role to the spatial distribution of water ice and permanently shaded lunar South pole craters so that said let's go ahead and just start this presentation.
Pedro Montalvo: So, before going into details of the study, I would like to get some background information related to water is in the Lunar South pole.
Pedro Montalvo: So i'm Recent studies have detected the exposed wires on the permanently shaded regions of them are softball.
Pedro Montalvo: And we can see this on the finger on the left here that i'm highlighting with my mouse, so this map is showing detective water ice exposures, which are represented by.
Pedro Montalvo: The Green dots in this map, and these were detected by the moon mineralogy mapper or n cubed for short so Evidently, we can see that such exposures are located within these permanent shaded regions which are denoted by these dark spots in this map.
Pedro Montalvo: So these water ice exposures have three proposed main sources and these can be seen here on the figure out the right.
Pedro Montalvo: And these are impacts by asteroids and comets volcanic outgassing and solar, wind interactions with the Lunar surface.
Pedro Montalvo: Also volatiles and placed on the Lunar surface migrate to the polar regions and are eventually cold trapped in permanent shaded regions, and you can see that, here in this figure that they just bounce and eventually get cold trapped in these little areas that are cold enough to.
Pedro Montalvo: contain these bottles.
Pedro Montalvo: So i'm mixing up the Lunar regolith do to impact, creating events has been modeled and will studied over the years and the idea is that.
Pedro Montalvo: As an impact event occurs some region will be overturned or mixed, and you can see, this on the schematic on the left, which is showing the geometry of an impact gardening.
Pedro Montalvo: and showing how material is behaving during an impact event, we can see that, when an effect occurs materials being vaporized melted projected sprawled and at depth even displaced.
Pedro Montalvo: And in a simple manner here on the right side of this figure you'll see that most of the region within the transient craver crater cavity will be mixed.
Pedro Montalvo: So on the middle of the slide, you will see a schematic showing the different regular regions upon the formation of a simple crater.
Pedro Montalvo: And two key regions here are the better lens, which is a region more melton shock to rocks will be mixed in, and the objective blanket outside of the crater rim.
Pedro Montalvo: So here in this study we just focus on the bridge lens region, because it is where most of the mixing will occur and a scene by these.
Pedro Montalvo: Regular fixing that profile on the fly right the red line is showing you the ejector only and the.
Pedro Montalvo: Gray profile is showing you a brush and lens so most of the mixing occurs there.
Pedro Montalvo: So, for the purposes of our study, although this is under still under debate we interpret the material mixing depth as regular thickness.
Pedro Montalvo: So if the depth of where material is being mixed by impacts also means how thick the rival that will be, then we can interpret this as an inferred water I step, or what depth water is will be mix.
Pedro Montalvo: With the Lunar regolith in permanently shaded areas, so this allows us to explore how water is is distributed a local scales both horizontally and vertically, so therefore.
Pedro Montalvo: constrain the spatial distribution of water is in these permanently shaded regions so here on the left, as seen in the previous slide are the Lunar salt polar water ice textured and the red circles show the regions of interest for this study.
Pedro Montalvo: On the right, we see a hill shaded elevation map of the target craters and the elevation is in kilometers and I will be describing the reason the following slide.
Pedro Montalvo: Okay, so the study areas of these.
Pedro Montalvo: Are these three South pole or complex graders that have permanently shatter floors, and these are howorth shoemaker and frosting right here on the bottom, and these are highlighted by the dash red circles on the elevation map.
Pedro Montalvo: These creators were selected because one they host PS ours and their cregger floors which are the Gray ish areas here in this map.
Pedro Montalvo: They host surface water eyes, which are the white polygons that you can see, within these red circles and, finally, because the geologic conditions of these craters have been well studied.
Pedro Montalvo: So if I can direct your attention to the table, these are the model ages for the have been previously documented and for these graders and they were about 4.12 4.2 billion years which correspond to the predict tyrion in the Lunar geological time scale.
Pedro Montalvo: Okay, OK, so we first performed critter county in each target creator Florida, as you can see in the top three slope maps here.
Pedro Montalvo: And because our target areas are impermanent shadow, we were required to use lunar orbiter laser altimeter or Lola the M and derive hill shade and slope maps to count craters in these regions.
Pedro Montalvo: So the kind of craters are shown as the red circles and the outline is blue is the counting area, which is the creator flow region.
Pedro Montalvo: The plots below are cumulative size frequency distribution or CSF these for short that we obtained for each quarter.
Pedro Montalvo: floor and from this from these plots we obtain model ages by fitting the know I can production function, which is represented by the solid black line in the each plot.
Pedro Montalvo: And howorth we counted 834 craters and thing a model age of about 4.1 GA in shoemaker we can total of 685 craters and we can obtain a model age of 4.1 GA.
Pedro Montalvo: And lastly, for for stealing we counted 1319 graders and obtain the model age of three point GA and total we counted a little over 2800 craters.
Pedro Montalvo: and note that the ages of thing in this study for Howard thing shoemaker are with an error with with previous work but frosties he is slightly younger.
Pedro Montalvo: OK so moving on to the mixing depth model we applied this regular mixing desk model, which was developed by co author hereby hero by yeah she and others.
Pedro Montalvo: To investigate what depth water eyes may reside at the creative for scale and each of these traders.
Pedro Montalvo: So this model uses the fitting creative production function as an input and allows us to analyze the material mixing depth in those regions which, again we interpret as the depth where water is Member side.
Pedro Montalvo: So we consider material mixing depth at a 0.9999 area or at the 99 point 99% level and the main reason we chose this area fraction is to ensure that the right depth.
Pedro Montalvo: represents the mixing nature of the entire regions so looking back again at the CSF these for each critter floor as you can see here on the Left plot.
Pedro Montalvo: We can see that creator distributions are different between greater floors and each dash dash line shows the creator production function fit.
Pedro Montalvo: So we then calculated to limits of the material mixing depth the creator for scale and obtain an upper limit, ranging from about 1.3 2.3 meters and lower limit from point A to point 98 meters, and these are consistent with previous works.
Pedro Montalvo: So the mixing desk profiles shown on the plot of the right also show mixing the spatial heterogeneity between each created.
Pedro Montalvo: So from this, we can see that both Howard and shoemaker show deeper mixing and fostering new shows lower mixing.
Pedro Montalvo: Okay, so to investigate the distribution of water eyes up a local scales or a high resolution we developed three measurement grid systems at three different sizes and obtain the creative production function fits for each of them.
Pedro Montalvo: So the greets the grid sizes are swallows and the largest good sizes 7.5 by 745 kilometers, as you can see here in the first column.
Pedro Montalvo: And the intermediate good size is five by five kilometers shown in the middle and, lastly, the smaller sizes 2.5 by 2.5 kilometers shown on the last column.
Pedro Montalvo: So know that there are some regions without grits, and this is because we exclude a grids that contain a total number of craters less than eight and we did this because the creative production function fitting was quite difficult than those grids due to lack of samples.
Pedro Montalvo: So.
Pedro Montalvo: The space, the spatial distribution maps here are showing the upper limit of the inferred more I said but different grid sizes and they range between point one meters to 13 meters deep.
Pedro Montalvo: So we find that not only the material mixing is different between crater floors but it's also spatially heterogeneous between good sizes within each crater.
Pedro Montalvo: We also found that the mixing material depth depends on the crater size within each grid, for example on grids that contain larger craters showed higher mixing and you can see that.
Pedro Montalvo: For example, looking in hallways we have a lot of large craters and show very high mixing depth and grits that mostly have smaller craters show lower mixing the valleys, so therefore the water is that is controlled by the crater distribution that is present with each grid.
Pedro Montalvo: Now this slide is similar to the previous one, and these are the same spatial distribution maps but we're showing here the lower limit water I step and This ranges about between point oh three meters and 8.8 meters.
Pedro Montalvo: And again, we can see that the trends are similar here, compared to the previous case.
Pedro Montalvo: Meaning that in Greek grids that have larger craters the mixing that will be higher and lower and the presence of smaller craters.
Pedro Montalvo: Okay, so.
Pedro Montalvo: Our findings show that the mixing the very much depends on the crater distribution in each locality that at least it has been mix out a depth, ranging from point oh three meters to about 30 meters.
Pedro Montalvo: So what the staff mean for water ice there will arm our results suggest or in a way predicts that in regions that host a larger craters water ice is deeply distributed and therefore less concentrated vertically in that particular location.
Pedro Montalvo: So, in contrast.
Pedro Montalvo: regions with smaller craters present will have less deeply distributed water eyes and therefore more concentrated of Berkeley.
Pedro Montalvo: Another interesting finding from this study is that our model vertical distribution does not correlate with the observed water ice distribution on the top surface that is suggested by Lee at all, and you can see that, here in the bottom figure or all these.
Pedro Montalvo: bluish areas are the same polygons I showed in the first few slides.
Pedro Montalvo: These are the lead at all water surface water ice protections and some of them are not evenly correlated with our distribution.
Pedro Montalvo: So this this propensity may imply that water is on the top surface has been transported in a relatively short time scale.
Pedro Montalvo: So, if this is the case, then the craters geologic age and the water ice condition may be independent and may also suggest some form of active supply and removal mechanisms that have play a role to the motorized evolution.
Pedro Montalvo: So some of these some of the processes that cost that may be causing this ice redistribution may be micrometeorite impact solar when sputtering.
Pedro Montalvo: lunar true Poland want wonder, excuse me and volatile transportation to pieces, from other regions of the moon, like the equatorial regions.
Pedro Montalvo: So if these processes are more rapid than impact mixing, then the supply exceeds the mixing and it keeps the ISIS on the top surface of the PS August.
Pedro Montalvo: So this means that the chain between the mixing and the supplier should play a critical role and controlling the goodbyes conditions and PS ours.
Pedro Montalvo: Okay, just to quickly summarize the study we've analyzed how impact and use material mixing contributes in a statistical sense.
Pedro Montalvo: To the water is distribution in permanently shaded regions, we also explore the permanently shaded floors of howorth shoemaker and faustina by performing credit accounting and applying a statistical approach.
Pedro Montalvo: few minutes okay.
Pedro Montalvo: One or eyes may exist or maybe pressing a depth at least point.
Pedro Montalvo: Three meters to 30 meters and are mixing depth distribution does not correlate with the observed water ice distribution, which implies that actually supply and removal processes of water ice Okay, so I just would like to thank.
Pedro Montalvo: These.
Pedro Montalvo: People and grants and the PDS geosciences node for making this own study possible and parvati pram Emily costello and Kevin Kevin for useful discussions and with that I would take in questions, thank you.
David King: Thank you, Pedro on.
David King: So the papers so open for questions.
David King: From our our viewing audience.
David King: The.
David King: Possible volcanic sources for the water.
David King: Is is the timing of that just to think the vibe assault in placements or anything there might be some other.
David King: candidate to be more recent than me contributing.
David King: Or do you know him since.
Pedro Montalvo: There are some studies, I think.
Pedro Montalvo: Jim head did a study that the timing was too.
Pedro Montalvo: Short, I believe, for these to be the actual source and that's another debate, it may be a source, but not as much as the ones that I mentioned so generally those three sources are.
Pedro Montalvo: The most widely accepted sources.
David King: Is there.
David King: An overall motivation for this kind of work because, for some reason why we.
David King: just have an academic interest want to find any water.
Pedro Montalvo: yeah so yeah so they're they're the main there's motivation for this and it's um more economic I would say there are.
Pedro Montalvo: Upcoming future lunar missions like ARTEMIS that they want to not only sample to understand this water but use this water eyes as a resource, because they want to make a little moon base over there and.
Pedro Montalvo: Get people there to work in situ so having water and using it as a resource would allow a lot of like fuel, for example, drinking water.
Pedro Montalvo: So understood like knowing where the water is could potentially aid, how to mine it how deep, it could be essentially.
David King: If he went there.
David King: In terms of samples that regular these he could actually see the one in sample you think it's just.
David King: To spring.
Pedro Montalvo: Well, I think, if you, you may see it as.
Pedro Montalvo: A gluten it's maybe some sort of mix of regolith and particles of ice i'm not sure if it's going to be pure eyes, but some of water will be there um and.
Pedro Montalvo: Based on our results it's going to break up and it's gonna it's not going to be a chunk of ice it's going to be more like finds in sand or like in regular.
Pedro Montalvo: And that may be different on depth, I suspect, but close to so First, it might be more like.
Pedro Montalvo: particles.
David King: Thank you very much switch over to the next presentation that may mean that you need to.
yeah.
David King: so nice presentation is recorded and play it for you on it has to do with depletion of crowd small craters on the walls larger writers.
David King: The.
David King: speaker is lauren talking to his master student in our department she's been co supervised by masatoshi here bashi from aerospace and auburn and me, and she said she's also been mentored by an instrumental and so she cannot be with us this morning and such show on.
David King: The screen time and answer questions.
Julia Cartwright: If we can't have this talk.
David King: i'm playing it and I.
David King: know many of you know we can because we arrangers earlier.
Julia Cartwright: there's two things you either need to share your audio content with the share screen, or you need to unplug your headphones and the major in my computer to them broadcaster.
David King: and welcome to presentation, my name is lauren talking, I have a master's degree.
David King: auburn university working on my degree in geology and i'm really excited to get to share the research that we've been doing over the past couple months with you all.
David King: And i'm also excited about the fact that you have an interest in it as well, so without any further introductions let's go ahead and get started.
David King: So as an introduction, we know the craters on the moon are exposed to numerous impact events posts and placement and because of this typographic diffusion is slowly degrading the craters by emplacements of spa craters on top and around them.
David King: So we can see different rates particular graphic diffusion between comparing Scott amundson.
David King: These are both complex craters that are found within South Pole and there are about 100 kilometers in diameter.
David King: So we see in evanston steep was clear and teachers terraces and a central peak.
David King: But if we look at Scott, we don't really see these features, we do not see it evidence for a central peak we do not see clear him features and we also are not really able to distinguish the walls from the floor region.
David King: The observed terraces gave us critical understanding of the events posts and placement of edmonson by showing us the remnants of landslides or mass movement events.
David King: And these observations are fundamental in our research process because we explore how to the graphic diffusion effects complex crater degradation by investigating the crater distributions on their walls.
David King: In this study we look at complex clear mythologies of 16 complex craters found on the Lunar southern Pole and we did this to better understand the wall degradation and how has influenced posted placement by meteorite been bartlett's.
David King: we've Lola D amp data for the PDS geosciences mode of Washington University in St Louis.
David King: Within the D and we collected our data by credit counting along the walls of the complex craters using Arkansas and the creator tools.
Julia Cartwright: David you just muted yourself, so we.
Julia Cartwright: can't help the speaker view.
David King: Each crater extrapolates the rim.
David King: By connecting the three points.
David King: We use this because we determined that it is more accurate than the two point method when it comes to finding the true diameter of the crater and placements.
David King: The next step in our analysis was to determine the slope environments for the crater emplacements.
David King: The reasoning behind this is so that we will be able to see what crater diameters have found that higher slopes.
David King: To take this a step further if we get to.
Julia Cartwright: Did we couldn't he again.
David King: buffer analysis tool.
David King: and create a 20 metre or one pixel buffer around the rooms of each crater We then use the Ad surface information tool to calculate the average slope from our slope overlay.
David King: The diameters and average rim slopes were saved within the rim buffer attribute table which we export as a text file and further converted to a csv using excel.
David King: We repeat this process for each of the 16 complex craters we included in our analysis he clicks 7905 counts and total the average area for all the 16 craters this 2,205.06 square kilometers.
David King: Finally, we defined craters on the walls, a circular features with central depressions so features that met the criteria were included within our data collection.
David King: This is an example of what our results look like when we finish crater counting on the walls, in contrast to create a counting on the floor, the walls are sloping rather than flat.
David King: This makes crater counting a little bit more technical in determining what to count as a crater versus what to leave out at the analysis for these regions and to do this effectively, we had to determine constraints, for what we would consider a crater.
David King: To combat bias within our study we counted craters, ranging from 99 meters to nine kilometers in diameter.
David King: By doing this, we will be sure that craters that fall within the sub kilometer range are small enough to be considered craters to significantly reduce the risk that we would reject them based on size or morphology.
David King: The shape files you mentioned previously, can be seen in the legend here defined as the wall area and craters In addition the variations in slope of the wall of fussiness are defined beneath them.
David King: To get our results we compiled the accounts and use Python to create some plots The first of these is our histogram and we can clearly see that the largest crater population belong to the less than equal to 700 meter diameter craters this Ben had 7251 craters.
David King: In addition, we can see that these craters range from very shallow slopes to very steep slopes.
David King: For craters greater than 700 meters shown an orange and purple the population is much smaller and they're found at a much tighter range of slopes, we use this discovery within the next few plots to further investigate what our data is telling us.
David King: By using a combined CSF D plot we noticed an interesting feature at the 600 to 800 meter mark this represented by the block dashed lines, and the figure.
David King: The SOFA crater diameter smaller than 600 meters is about negative three by the SOFA craters divers larger than 100 meters is about negative one.
David King: We plot it the newcomb production function as a black line, giving the model age to be about 4.1 giga years, however, this is likely, an overestimation in the crater population This implies that there were some depletion processes that were occurring.
David King: In this case, the larger craters would be enhanced by some large scale landslides, but should be typical phenomena for impact events on sloping surfaces.
David King: We consider this a transition because we see the population of craters declines drastically for craters larger than 800 meters.
David King: And if we take a slip out of consideration we expected to be more craters with larger diameters and the smaller ones, this is because they will not cause mass movements and subsequent partial or total eraser of the crater cavity.
David King: We can see this is complimentary to the histogram plot illustrating that the larger creative populations are found in the show or slope regions.
David King: And we've noticed that there may be some smaller craters that we did not consider for analysis, however, this is not affect our results, implying that craters larger than 800 meters are missing.
David King: So far, we have to determine that larger craters are depleted due to the land side events that are impactors are capable of inducing causing partial or total eraser of the crater cavity.
David King: In addition, we have determined that smaller craters remain visible on the walls, because it impacts are not capable of inducing landslides.
David King: Using this understanding, we consider the surface strength on the walls and to do this we computed the shear strength of the walls capable of preventing landslides from occurring.
David King: We also use crater scaling relationships to compute conditions for larger features.
David King: shear strength is determined by looking parallel or along the wall surface we determine that we can derive the lower bound of necessary conditions to make landslides in two ways.
David King: First, there needs to be a landslide thickness of 180 to 240 meters and thickness This is also the transit crater diameters for craters with diameters 600 to 800 meters.
David King: Next we calculate the necessary or shear strength that would prevent a landslide of it from happening.
David King: To do this we use the equation row times gravity times high sign of the slope ankle.
David King: We use our high is are necessary landslide thickness so the 180 to 240 meters the sort of angle of the walls as 30 degrees, the density for lance headlock row as 3000 kilograms per meter skewed.
David King: We interpreted that since the slope would already be determined before the craters weren't place finding the derive strength with service as a lower bound for the production of landslides so once we derive the lower bound we turned our attention to the upper bound.
David King: We deduce that the currents of landslides themselves may serve as the upper bound, otherwise the strength, would be able to withstand the impacts and elaine side would not have been.
David King: Using are derived slope string of 0.5 to 0.7 mega pascal's we can interpret that the wall structurally weekend due to the emplacements of the host and creator and the subsequent post-dated smaller craters.
David King: The depletion of craters with diameters greater than 600 to 800 meters implies that landslides will be large enough to erase their mythologies and crater cavities.
David King: To begin our interpretations be incorporated impact crater scaling relationships in our analysis we use the pie scaling relationship by connecting energy quarter size, the material strength.
David King: By doing this, we can extrapolate what we see within smaller features to larger ones.
David King: shown on the slide is the equation, we used where V represents the transit crater volume in my row I and Ai projectiles mass density and radius respectively.
David King: roti is the target density GE is the gravity VI is the impact speed and mew K one and why far for experimentally drive properties, the target material connecting all of these parameters allows us to compute the crater diameter, given the impact your diameter speed and bulk density.
David King: to determine the characteristics of strength within the gravity and strength regimes, we need to define a few things first is the F ratio, also known as the crater size to impact or size ratio.
David King: To make this plot we assume that impact or speed as 15 kilometers per second and at the target density and the impactor density were identical the F ratio ranges up to 30 to about 45 and the grab the regime, due to the weaker strength associated with the size ratio.
David King: When F is equal to 10 the strength reached around 125 to 305 mega pascal's.
David King: The red line describes the one mega Pascal line indicating the strength transition between the gravity regime and the strength of gene.
David King: This is important and understanding, because if we can determine that the craters found on the wall belong within the gravity regime.
David King: This is conclusive with our results that show that there are a larger population, a smaller impacts, this is all on the walls, due to their energies not being strong enough to induce landslides.
David King: Does if the strength is less than one mega Pascal to create a formation is in attend the gravity machine and we will see more smaller craters otherwise it occurs within the strength machine.
David King: In summary, we to do so, the large population of craters smaller than 700 meters implies that they are not large enough to produce landslides.
David King: We noted that there is a transition found at craters with diameter 600 to 800 meters we attribute this transition due to the land side eraser fall morphology.
David King: we've further investigated this transition by using crater counting and impact crater scaling relationships and we can derive the necessary or shear strength, giving us our lower bound for wall strength about 0.5 to 0.7 mega pascal's and the upper bound, as the landslides themselves.
David King: Because of this, the impact is capable of forming 700 meter craters did not have enough energy to induce landslides.
David King: The transition, we noted is due to larger impactors having enough energy to induce landslides, causing partial or total a ratio of the crater cavity.
David King: And the shear strength may be 0.5 to 0.7 mega pascal's implying the variations and the strength and fragmented and and fragmented surfaces Finally we determined that if this is the case, we must account for the strength variation to assess impactors physical properties carefully.
David King: to wrap up here some final thanks I would like to give and support of this research or to the Department of geosciences at auburn university and this research would not have been possible without the use of Lola data from the PDS geosciences node Washington University of St Louis.
David King: hello, and welcome to my presentation.
David King: So, as I, as I mentioned, and it's talking to.
David King: can be with us this morning, but the talk is open to discussion, if there are any questions.
Julia Cartwright: I could ask the question am.
Julia Cartwright: I I was going to ask whether they considered the gravitational force of the name and the equation that she showed this show that i'm.
Julia Cartwright: I was wondering if they see a massive difference if they start messing around with that gravitational force or not, and whether that that changes the output and see.
Julia Cartwright: That now if you have any.
Julia Cartwright: idea on that David or an pedra if he's still around.
Pedro Montalvo: yeah i'm still here i'm i'm not actually sure how to answer that.
Pedro Montalvo: yeah sorry David Germany.
David King: So she would she would need.
David King: To be here because yeah he's mentored her in the in the in the word, but I know that there were Luna gravity and taking that into account, I think that's in part of her equations but.
David King: yeah it's.
David King: it's kind of interesting finding know that there's two there's actually a size cut off for the book Katrina landslides that's that's interesting yeah I know they're taking that into account, but i'm sorry I can address it specific.
Julia Cartwright: For different competitions.
as well.
David King: i'm sure that I missed a few words in your question.
Julia Cartwright: um do you know if they counted for different compositions and the Lunar was like whether they considered, something that was more kind of Highlands rich versus like maybe something that had a lot of margin or whatnot.
David King: Know malicious assumption, and it was all not really so much interest.
David King: make their estimations.
David King: You know, easier from.
David King: Almost two to the time or next talk so I have was looking to see if our authors were there.
David King: Are dark woods, if you could queue up your.
David King: First slide oh great.
zexi xing: it's me.
zexi xing: So I can I share the screen.
zexi xing: yeah.
zexi xing: i'm.
David King: surfing.
zexi xing: Okay, can you see my slides now.
David King: I can see.
David King: yeah.
he's doing yeah.
zexi xing: So i'm super see from the University of Hong Kong, you can also call me Lucy my English name given by American front, so my Supervisor is Danny spooky ways from auburn university.
zexi xing: So in this talk I like to talk something about the auto valid structural study about potatoes, have you seen this figure.
zexi xing: Well, in this April fool's day.
zexi xing: I will talk about, we have the rotating potatoes in the universe, the asteroid.
zexi xing: that's not it on I think they look pretty similar you know they create her surfaces the regular shapes but that's not the only reason why I put such a figure here.
zexi xing: I specialty fun this try color potato figure at my cover you know the common potatoes, the floor and rather ones, because I can, I think they can somehow.
zexi xing: imply the colors of asteroids so soon, I will show how but before that, so let me first and least what what have you talk about today so.
zexi xing: First, I will introduce what instruments how our actually observed asteroids UV and then I will on.
zexi xing: us some results are these observations to show what we can learn about asteroids in actuality in you.
zexi xing: And after that I will turn to our own study what we did with with this swift of the lottery, and finally, we are, we are still doing our data reduction, so we do not have many results to show so Finally I will only give some preliminary results and.
zexi xing: So.
zexi xing: i'll tell that photons.
zexi xing: coming into the upsell by also and seeing the earth's atmosphere, only some year ultraviolet photons can be some somewhat left to be detected by the ground based telescopes back and he.
zexi xing: is shot his the wavelength is at 320 nanometers so ultraviolet ultraviolet is from about 400 to 400 nanometers.
zexi xing: On space test groups are necessary to detect the signals from lower maryland's so but but that's requirement have a limit the number of your a telescope.
zexi xing: On and on so telescopes which have observed asteroids us structure can realize, I think I have put all of them here so among those on I you he is the first one.
zexi xing: It has observed about tons of asteroids and on his estate is still pretty valuable and you today swift and hubble are the only two away she's doing all of it, but because I was a competitive observing time Hello.
zexi xing: can only do some scattered observations for the asteroids you'll be swift the work is our work, which I will introduce later, besides some spacecraft to also make flyby you way observations for the asteroids.
zexi xing: um there is almost no summer radiation in the also valid through banned from the asteroids on almost all of them come from the reflected solar flux.
zexi xing: So compact by comparing that the comparison between the solar as an asteroid flags can tell us and seeing about the surface of the asteroids.
zexi xing: And so you already take the ratio between these to cancel specter and we get this picture of a coin reflectance spectra so any variation within this reflectance one can indicate some differences between this the solar and asteroids flux.
zexi xing: Are Here are some examples of the of the reflectance spectra from some some lunar samples, so you can see, there are there is much variation in this reflectance.
zexi xing: You can see this this large absorption feature here and the intensity contained a lot and the smokes can also Chandler Chandler lot with with different wavelengths.
zexi xing: On the ladder slops mean there, there is hot there's more light reflected in the longer wavelength in the show turbulence, so that is that reflected light can be rather for this largest load.
zexi xing: On you can also see, there are two groups of of reflectance the green blue lines are from the Lunar soil sample which are more lathered.
zexi xing: Was it yellow and orange ones are from the crush the Lunar rock samples, which are less weathered and so you can find the mall either samples, they are dirty talker and then this, then this.
zexi xing: Then this rock samples, and they can be they have less absorption features and more interestingly on they have.
zexi xing: So relative to this truck samples, they have higher or riders lows in the long wavelength, but shot her or blowers loss in this, you will find this is more of beers in this finger on, you can see, all of the soil sample our ethics as this corner, they have.
zexi xing: Low or blue slope in the UV or high end report and high or right sloping the infrared movement so tell us there may be a close correlation between space Valerie effects and the reflectance features, so this feature has also be seen for the St Joyce on so here.
zexi xing: So, here are some data from the as tap as to Joyce So these are, the more weathered as tough as Royce and this black.
zexi xing: Black points are some other record right media rise, which presumably throughout from as tough as asteroids so they are less bothered and the asteroids are more lathered.
zexi xing: And the comparison between them is pretty similar to that between lunar soil us and the Lunar rocks and that's why I proved that try color for tatum figure either color.
zexi xing: On the constant mall lathered as choice you either in the in the long weekend and blue or in the UFC event at the same time, so i'm.
zexi xing: So starting your flaccus features can help us and seeing about the space feathering.
zexi xing: um but until now that sells out after your eyes when mothering is still under debate you know the weathering include solar, wind implantation or.
zexi xing: On macromedia right from Parliament and some modeling I study show that the addition of non office Aaron to green coatings can either away these absorption edge and make an flatten it like this.
zexi xing: So that the reason why it becomes lower in that your baby and and they also find you we can be super sensitive to the idea amounts of nano face air and you already more sensitive to that the long wavelength.
zexi xing: On.
zexi xing: This as a devotee is also supported by some lab results.
zexi xing: At showing here, but I do a little among soft Aaron can change the reflectance from this one to this one so 11 trace amounts of metal bands can call the intense mito oxygen tank transfer absorption in ultra violet and then darken and the flight and the overall reflectance spectra.
zexi xing: The size on some people also find the UV on you, we find is also sensitive to the Queen size, so I showing this figure.
zexi xing: On the larger surface Greens on the you already have similar effects as more abundances so to separate the effects of green sideways from abundance is on we can perhaps use these episodes deeper and deeper absorption feature on but more your we started is also necessary.
zexi xing: And besides the overall color there are also many other interesting features in the UV reflectance, for example, only for as your voice has been started is.
zexi xing: lower than 220 nanometers but now the spectra senior as shown here on the black curve either affect reflectance of psyche on there.
zexi xing: There are some absorption features at around 250 and 275 centimeters but um if this black curve can never be fixed it pretty well these other things need to rise or arron or.
zexi xing: Also mixed models on, there is also an uptrend i'd shoulder than 200 nanometers with unknown source on perhaps East edge of a bump at at near you we reopened.
zexi xing: So, like what happened for the series is orange curve to bump here on new tag yeah the asteroid has a has a sharp absorption edge and here.
zexi xing: But it's um it's reflectance is not continuous caused by different instruments so it's hard to analyze understands this asteroid has similar reflectance with psyche at around 200 nanometers but they deviate at lower everlands.
zexi xing: So more your way abductions or sorry more your observations I needed.
zexi xing: Because you we sensitive to metal abundance and the Green size and you, we can be more sensitive than longer wavelength.
zexi xing: So we can use it to start any space mothering or surface properties because different surface properties can react differently to the.
zexi xing: To the battery and asteroids can be complex, there can be fresh cratered always lie there the surface, there can be a larger impact which expose the Interior.
zexi xing: Or, there can be heterogeneous conversation for a single asteroid so i'm more observations can allow us to to do some global conversation distribution study or to make a statistical you have a tax taxonomy and family to build formation and evolution history file for the asteroids.
zexi xing: So to.
zexi xing: obtain more you'll respect for of the asteroids are a team has used swift observatory to.
zexi xing: To to observe at asteroids until today on SWIFT is initially designed for gamma Ray burst know like expected that it could play an important role.
zexi xing: For starting solar system small bodies.
zexi xing: With really strong your way ability so also is spectral resolution is low, but he's very bad cover evaluation.
zexi xing: So from about 160 nanometers to about 600 nanometers that's that's pretty cool because it can connect me, though, UV rays near you leave is visible with fans and this can be applied her continues spectral coverage and allow us to start the the specter of a slice uncertainties and this.
zexi xing: This continuous coverage can also feel that gap between these these different events, so the.
zexi xing: blanket is from 300 to 400 nanometers so that's cool because i'm the strongest so as showing this to figures, the strongest blowing trend is just seen in this branch and absorption feature within this range can also indicated some grew in size and problems.
zexi xing: And so, he has Joyce has been have been observed, but some some of them are too bright for for swift exam such as series and some others.
zexi xing: have some crowded star backgrounds so Finally, they can only do we can do the data reduction for 11 zone and every every asteroid was exposed to four, five or six times to start using rotation effects.
zexi xing: i'm like to take take the asteroid to know as an example to show the results.
zexi xing: So the light from drew know can be dispersed or on the equation image and this is a serious order.
zexi xing: There was All there is is Porsche and dizzy the first order so this one is saturated because to know his pride.
zexi xing: And this this bright light in the first order, it is widely dispersed, so we can use a slate and ios made to extract the flux spectrum, as shown here so different color.
zexi xing: Different differently colored curve on represent different observations, so the variation between them may come from rotation effects and the black curve.
zexi xing: is for a beer either average flux flux specter divided by the solar spectrum, we can gather reflectance on this.
zexi xing: Black curve is.
zexi xing: His fifth reflectance on its OK.
zexi xing: So it's.
zexi xing: Just connect is perfect, I think we've pretty well connect I use reflectance so the blue curve, to the mmm keys reflectance so that how as slaves to can give us a reliable continuous you with courage.
zexi xing: And the family, I put on the reflectors of all of the elements back Yolanda asteroids here.
zexi xing: We are still doing some data reduction reduction and how not analyzed in great to for this reflectance, but you can all but there seems to be indeed some relation between the reflect reflect tense and the asteroids as roy's taps and.
zexi xing: I can always follow some of tours in here, so the next step is to finish the data reduction first and we'd like to take on.
zexi xing: To pick.
zexi xing: Right first to do the cases it and after that we will do more comparison and statistical work so that's my talk, and this is a summary for the questions, so I like to take some questions.
David King: Yes, thank you so much, and.
David King: papers open for discussion.
Julia Cartwright: This yeah I have a quick question, you mentioned that you're going to be picking.
Julia Cartwright: One asteroid as a case study and have you thought about which one you're going to be going full.
zexi xing: I like to take psyche first because.
zexi xing: Last year theory the paper from from this paper from huddle observation is just observed psyche and we'd like to to start the psyche first and compare our results with fear fear results and to make our results more reliable.
zexi xing: And theories, the mission of psyche in 2022 yeah.
zexi xing: yeah.
zexi xing: Oh.
Colin Jackson : You mentioned that the as the continuum within the UV is sensitive potentially to both space weathering and to composition.
Colin Jackson : I like you're correlating yeah, this is the finger thinking about correlating the slope versus the UV slope and clearly there's a little bit of scatter within that.
zexi xing: correlation is that it's.
Colin Jackson : Possible I guess is there some way to interpret that scatter in terms of.
Maybe.
Colin Jackson : Do you see where i'm going with a question or.
zexi xing: yeah, thank you for question, so this paper i'm actually talk I think use two paragraphs to talk about this question on the on the so on these are some about.
zexi xing: About 20 s voice and and the separate sorry good this as your so called into their spectral taps and on and talk to reasons, according to the spectrum of taps um so I remember the mind reason for this is should be the head heterogeneous conversation on the surface.
zexi xing: For example, some some some can you pretty blue in the movie but not so so right in the Info right on so.
zexi xing: I remember the country field to face to the.
zexi xing: Competition distribution but sorry I don't remember the details.
Colin Jackson : Those are those are the more those black data points more reduced ask for a pair of bodies.
zexi xing: Are from some media wise.
zexi xing: So.
zexi xing: The Nice neither.
Thank you.
David King: Tony you can go to.
David King: The next three talks okay.
Colin Jackson : Oh yeah I can take over is for the final three presentations of our session so let's move on to our next presentation.
Colin Jackson : Do we have mark boyd in the room.
Mark Boyd: i'm here.
Mark Boyd: Great.
Colin Jackson : Let me introduce mark mark boyd and co authors will present a talk titled investigating the effects of atmospheric entry on cosmic dust.
Colin Jackson : Using Adam prob tomography so take take it away.
Mark Boyd: Great Thank you so much, Dr Jackson for the introduction, so my name is mark and i'm a graduate student here at the University of Alabama.
Mark Boyd: And i'm really excited to be sharing our results from our atom probe analyses on cosmic dust and don't worry i'm going to explain explain what all of those things mean and the coming slides.
Mark Boyd: So, before we start, I want to give you an idea of the kinds of skills that we're talking about because we're working on a few different kind of resolutions and scales.
Mark Boyd: So i've put up a kind of scale chart in the middle here a logarithmic scale chart from a centimeter down to a nanometre and there's some familiar.
Mark Boyd: kind of geological phases here so in the top left, we are the garnet green approximately two millimeters we have an edge, which is about half a millimeter.
Mark Boyd: And then the cosmic dust particles that we're looking at in this study is on the 10s of microns range so we're talking quite small.
Mark Boyd: But when we come to our atom prob analyses we actually remove part of the some of the material from this sample, and that is on the order of hundreds of nanometers.
Mark Boyd: And the reconstruction that we on i'm sorry yeah hundred nanometers but the reconstruction that we actually make is on the order of about sort of 10s of nanometers and so we're talking about very, very small scales here, so I hope this kind of orient you as we dive into the results.
Mark Boyd: So cosmic dust is a term that's used to describe micrometer sized extra terrestrial material and it's thought to represent the built the building blocks of the planets and planetary bodies in our solar system.
Mark Boyd: it's been estimated that about 60,000 tons of this material is created by the earth, every year, and this is the equivalent to about five and a half thousand school buses so it's a significant reservoir of material that we're looking at.
Mark Boyd: And we can look at two different collections, we have micrometeorites which are normally a bit larger up to about a millimeter, and these are retrieved from the earth's surface and there's an image here of.
Mark Boyd: rudo collecting them from Antarctic ice and melting the ice to retrieve them.
Mark Boyd: And we also have a collection of interplanetary dust particles that are typically smaller up to about 105 to 100 microns that can be retrieved from the stratosphere.
Mark Boyd: But today we're going to be focusing on micrometeorites and it's important to study this material because it, as I said, it represents the planet building process.
Mark Boyd: And we often observe these dust envelopes around young stars, and so we can see how planetary bodies evolve as well as.
Mark Boyd: understanding how the solar system is evolving looking at collisions maybe in the asteroid belt and even looking at interactions of the earth with this material and starting to reconstruct things such as climate due to its interaction with the atmosphere.
Mark Boyd: And that's what i'm gonna be focusing on today how this cosmic dust is processed during atmospheric entry.
Mark Boyd: During entry, we have different part entry parts of these materials, and this can often be controlled by the parent bodies of these samples.
Mark Boyd: cosmic dust coming from asteroids normally come in at slightly slower speeds still very fast at about five kilometers per second race cometary particles and at higher speeds of more than 12 up to 20 kilometers per second.
Mark Boyd: And we can use the geochemistry of these particles, to give us clues about the heating that these cosmic dust undergoes as it enters the atmosphere looking at its chemistry and it's morphology and adding textures.
Mark Boyd: And these can tell us about things, such as the oxygen few dusty as they enter the atmosphere, the temperature of heating and the duration of teaching.
Mark Boyd: And so the hypothesis of this research is that micrometeorites and interplanetary dust particles are processed differently during atmospheric entry and today i'm going to be presenting our data on micrometeorite.
Mark Boyd: So the sample that we're looking at has been retrieved from blue ice at the Capri Dom station in Antarctica Antarctica a few miles from the doom on devastation showing here on the map.
Mark Boyd: And the reason we collect these particles from blue eyes is because its pristine, and this is a dry environment so it's unlikely that there's any terrestrial contamination or that these particles, they will undergo minimal terrestrial weathering.
Mark Boyd: And so hey is that image again of the micrometeorite that we're looking at it's about 90 microns in diameter and at the top, we have a.
Mark Boyd: scattered electron image showing some kind of compositional differences, due to the changes in contrast, and at the bottom, we have energy disperses spectroscopic maps which basically map the distribution of it in the bottom left and oxygen in the bottom right.
Mark Boyd: And I just want to point out a few features here that we have a really clear partitioning into a core and rem regions has a kind of rounded morphology which is.
Mark Boyd: typical of micrometeorites that have been heated and fully inflated and they end up forming cosmic ferals we also have dehydration cracks in the middle from dehydration of.
Mark Boyd: hydroxyl minerals and we can see that the rim from the eds maps is enriched in on an oxygen and this rim.
Mark Boyd: You can see in the bs in the backstretch emerge at the top it actually has compositional layering within that because you can see a contrast in the signal that we're receiving shown by the brightness.
Mark Boyd: So this is the sample that we've been looking at and before I show you the results, I want to explain a little bit about atom probe tomography.
Mark Boyd: Because this is a very new technique that's being applied to the geosciences in sort of the last 10 years or so, and so, if you're not familiar with it, hopefully this will give you a bit of an overview.
Mark Boyd: So item pro tomography allows us to create three dimensional nano scale maps of a sample by basically looking at a series of slices through the sample.
Mark Boyd: And so what we do is we map our particle as we've done here, this is a secondary electronic image so it's showing texture.
Mark Boyd: And we select regions of interest to remove material from our samples, and here you can see, we selected two regions of interest A and B.
Mark Boyd: And you can just about see in the secondary electron image that they are crossing over that core rim boundary because we're particularly interested in sampling understanding what's going on across that boundary.
Mark Boyd: Once we've selected our regions of interest that are about 25 microns long and two microns wide we used focus on being techniques to dig out a wedge from our samples, so this is a high energy gallium iron beam to remove material and create a wedge.
Mark Boyd: Once we've made our wedge we bring in a nano manipulator over the top of that wedge and attach it using a platinum weld and when we make a final cut to remove our wedge from the sample.
Mark Boyd: We then bring it over the top of a little silicon post, which is about sort of five microns in diameter.
Mark Boyd: And we weld our wedge to that post again using a platinum weld and then we cut it a little bit like we're cutting up a piece of cake and we repeat the series and to we exhaust that wedge, so we create a number of tips.
Mark Boyd: Once we have that tip on the silicon post, we then begin to Polish it down to create a really nice needle shape and once we've created that needle shape, we have to.
Mark Boyd: Give it certain parameters for the atom probe analyses, and that includes the diameter and the shank angle, and so we Polish it down, and we also do this to remove any kind of gallium on implantation leaving us with a an a tip or needle on the order of 10s of nanometers.
Mark Boyd: So, once we have this tip we can put it in the atom pro, and this is a schematic of what the atom probe is like and what it does so i'll take this shown here on the left and we call it down and we apply a voltage to our tip which induces a high electrostatic field.
Mark Boyd: Once we have this field we basically exact the the top of our tip with a laser and because of the lack electrostatic field this evaporates ions.
Mark Boyd: And these are accelerated by local electrode and they enter a time of flight mass spectrometer and our accelerated to a constant kinetic energy, which means we can differentiate them.
Mark Boyd: or understand what their masters are based on their different velocities they then enter the micro channel plates and are detected by the detector and this allows us to retrieve spatial down spatial information on the X, Y and zed axes to create a facial reconstruction.
Mark Boyd: And so, this is an image of the atom probe that has been used by our collaborators at Oxford University in the UK.
Mark Boyd: And the image on the right is to give you an idea of what you're going to be seeing in the coming slides, so this is an atom pro reconstruction of that tip that we put in to the material.
Mark Boyd: And on the access these acts, the numbers are in nanometers so we're talking about very, very small scales here.
Mark Boyd: And you can start to see there's some kind of heterogeneity within our sample because each.in this reconstruction represents, and I am that has been evaporated from our tip accelerated through the mass spectrometer undetected at the detector.
Mark Boyd: So i'm going to dive straight into the results that we've been getting and just to orient you the first tip i'll be showing you is from region be.
Mark Boyd: shown at the top of the secondary electron image and if you compare this to the BAT scattered image you'll see that this is taken from just inside the core rim boundary.
Mark Boyd: And here is that tip from that region and i've plotted on.
Mark Boyd: For simplicity, just to kind of make it easier to see we're looking at an iron oxygen species and carbon species, and we can see that there is a clear drain boundary within the sample, and this is a sharp compositional boundary between the iron oxygen species and carbon.
Mark Boyd: In figure be on the far right i've plotted an ISO surface, which shows us every point that it connects points of 20% carbon concentrations, this is quite a high concentration of carbon.
Mark Boyd: And i've plotted a composition profile through the zed axis of our tip.
Mark Boyd: And that is shown here on the left side of the diagram and it just emphasizes how sharp this boundary is it also shows you some of the trends we have in.
Mark Boyd: Elements beyond the oxygen and the carbon So there we, we can see that silicon really drops off as on oxygen drops off where we then suddenly have a large increase in carbon and a slight increase we believe in magnesium as well.
Mark Boyd: If you think back to that back scattered image, as I said, it's just taken from inside the call and this boundary isn't orientated with the Korean boundary it's actually about probably about 90 degrees to that.
Mark Boyd: And we think that it shows some kind of carbon nano scale phase, and these have been observed within cosmic dust particles before as graphite grains as silicon carbide grains and even nano diamonds, so it could be that we are looking at one of these phases here.
Mark Boyd: And it's interesting to note the morphology of this phase as well, obviously we're only looking at it constrained within the tip that we cut out from our sample.
Mark Boyd: But you can see that, within the tip it's creating a horseshoe shape but it's not a a Pole, region or is not a vertical within this region because other elements and ions plot within our reconstruction inside that region.
Mark Boyd: as possible, we may have some kind of pre existing phase that has been maintained through atmospheric entry.
Mark Boyd: I want to take you now to our other region of interest in region a and we're looking at tip em five and you'll see.
Mark Boyd: Or, I can, I can tell you from our secondary electron image that this tip we believe is taken from across the Korean boundary so we think it's sampling that boundary.
Mark Boyd: And tip em five was run in two stages, so the top, the first stage, the top half is shown in figure a here and the bottom stage shown in figure be and i've plotted again I so surfaces for.
Mark Boyd: iron and its associated oxygen complex arms in red for zinc in silver silver Gray, and for oxygen in blue, and we can see that there is a clear boundary again between these samples you'll note that it's a little bit more indistinct.
Mark Boyd: From the previous boundary that I was showing you.
Mark Boyd: But it's orientated with that call rim boundary that we saw and again i've made a composition profile to show you cutting across that boundary, we can see again here that's not so sharp.
Mark Boyd: But there is a clear increase in oxygen going from left to right and a decrease in on and also interestingly in zinc zinc follows similar behaviors to the iron.
Mark Boyd: And so, as this is consistent with the call rim boundary and because it's an indistinct boundary it may.
Mark Boyd: Be more likely to represent diffusion during atmospheric entry heating, rather than representing a pre existing phase within our micrometres right.
Mark Boyd: And it's interesting to note within this tip and some of the other tips i've been reconstructing that zinc follows the behavior of iron, which suggests perhaps that transition metals first row transition metals behaves in a similar way during atmospheric entry hughton.
Mark Boyd: And finally, I want to take you again to the same tip when we just we were just looking at across this core rim boundary.
Mark Boyd: and show you some limitations that we have seen within the sample So these are concentration trends for iron zinc copper and some for silicon elements or silicon and also some complex oxygen complex ions with silicon needs for about five nanometers in width.
Mark Boyd: Now it's been shown that fine enrichment can occur along voids and created by volatile loss and D volatile develop translation during atmospheric entry heating.
Mark Boyd: And so it's possible that these limitations are showing that along these along possible voids and we can see in the back scattered image here that we do have those voids dehydration cracks vessels for mangy to Lhasa volatiles.
Mark Boyd: These form close to that Korean boundary you saw on the previous slide and so it's possible they may be the product of elemental diffusion.
Mark Boyd: And it's been found that across these boundaries, there are high thermal gradients and so it's possible that these.
Mark Boyd: thermal gradient are causing elements of diffusion around that boundary and, in some ways that would kind of form sort of finger like dendritic structures around our Feral as it was forming adjacent to the core and rim regions along that boundary.
Julia Cartwright: And then it Thank you.
Mark Boyd: And so it's possible that these are the results of diffusion formed by these high thermal gradients.
Mark Boyd: And so, to conclude, we have shown that we believe that were the first group to apply or to perform at and probe analyses to characterize cosmic dust and, specifically, to look at a micrometeorite.
Mark Boyd: We think we've identified nano scale elemental phases, for example, within carbon and also these linear features and we've observed distributions that may well be controlled by the processes occurring during atmospheric entry heating.
Mark Boyd: So the reason, this is important, is because it can show us the earth has a dynamic interaction with extraterrestrial material particularly.
Mark Boyd: interactions with the atmosphere, and this can be important when we're trying to understand how the planets formed and also how they evolve during planet building processes.
Mark Boyd: And feature work we're hoping to refine the identification of the peaks from our mass spectrum which isn't always an easy task, particularly geological materials.
Mark Boyd: And we're also hoping to apply or perform at a probe analyses on an interplanetary dust particle to make a comparison to micrometeorite here.
Mark Boyd: So with that i'd like to acknowledge Dr Julia cart right my supervisor, for all her help and guidance and our collaborators are opposite atom probe.
Mark Boyd: For performing these analyses and being so generous with their time and efforts in collaborating with us so that brings us to the end i'd like to thank you very much for listening and I welcome any questions you may have, thank you.
Colin Jackson : Thank you very much, mark let's open up the floor for questions for the presentation.
Colin Jackson : One thing that caught my attention with your presentation mark was is a lot of times your.
Colin Jackson : As your atomic percents were quite low so is that a function of lucky, can you discuss I guess what goes into the calculation of atomic percent in this type of analysis.
Mark Boyd: yeah absolutely so a lot of our particles dominated by iron and iron oxygen and we have a lot of silicon in them, as well as you'd expect from having silicate minerals, and so it does mean that when we're looking at.
Mark Boyd: elemental species and complex on such as carbon which may be a particular interest if we're looking for certain.
Mark Boyd: sort of nano scale phases, it does mean that those proportions are going to be a little bit less and it's you know it's really important.
Mark Boyd: You know I think is you're kind of potentially pointing out in the question that.
Mark Boyd: We need to be careful when we're interpreting this data that it's not just a very small scale, because we're looking on such a high resolution on the anatomy to scale that these aren't just kind of.
Mark Boyd: You know localized I guess natural or normal distributions of these elements, and so I guess when i've been trying to reconstruct this data.
Mark Boyd: i've been looking for the sort of larger scale trends within the nanometers scale if that makes sense.
Mark Boyd: To look at how it changes within Arctic reconstruction and I guess being careful not to focus in on to smaller scale, because our abundances can be quite small and.
Mark Boyd: There is some kind of threshold there right when when you're trying to look at certain elements, not to go too low abundances with risk of it and obeying a significant result.
Colin Jackson : I guess, I saw in your carbon rich core you had a is almost entirely carbon, but the percentage was low, so my thought was are we looking at you know graphite or diamond or some of the pure carbon phase, or is this a carbide or is there, another element there that we're not sensing.
Mark Boyd: hmm yeah that's a great question so it's possible that there might be elements or species at very low abundances that we can't differentiate from.
Mark Boyd: This the background noise one thing about atom probe is that it has equal detection efficiency for all species.
Mark Boyd: And so that's the kind of encouragement when we're looking at the samples, but we can compare the reconstructions and look at different elements and a lot of them in that we're partitioning into the top half.
Mark Boyd: And, and when you start to if you're looking at any in the bottom part they had quite low abundances compared to the carbon.
Mark Boyd: I pointed out magnesium there had a slight increase as well, but it does seem to be dominated by carbon.
Colin Jackson : Other more questions from the audience.
Julia Cartwright: I can have a quick note as well that when we construct the ISIS services were only picking a certain amount of the data, so if to help them, reduce the noise so sometimes there's abundances those sensors I think are related to that maybe, mark you can comment on that.
Mark Boyd: yeah yeah so when you're making these ISIS offices is Julia said, you can you can set a certain level to show kind of.
Mark Boyd: The concentrations that you want to show and so often when i've been doing these as I was kind of saying like you tried to maximize that, so there is a high enough abundance that can still show.
Mark Boyd: The distribution that you're looking looking to show.
Colin Jackson : Thank you, thank you very much for your for your presentation let's let's move to our next author, I do we have.
Colin Jackson : You is Coco boxes on one.
Ioannis Kouvatsis: Yes, yes i'm here.
Colin Jackson : it's my pleasure to introduce you want us to have offices and co author Julia cartwright The presentation is entitled a study of milk.
Colin Jackson : class in Ukraine North West Africa 115 40, the floor is yours.
Ioannis Kouvatsis: So can everyone see my screen.
Colin Jackson : looks good.
Ioannis Kouvatsis: All right, great.
So.
Ioannis Kouvatsis: Hello everybody, and thank you for the introduction wake up to this presentation, so my name is Jonas and.
Ioannis Kouvatsis: i'm a PhD student at the University of Alabama and today i'm going to talk about the photography of you cried nwa 11 548 and also.
Ioannis Kouvatsis: i'm going to talk about a specific facing it and which is also present in other meteorites middle class and white, we consider middle class be important, so.
Ioannis Kouvatsis: First i'm going to say a few words about Ukraine which, together with our diets and by other nights are referred to us at these for short.
Ioannis Kouvatsis: And i'm also going to talk a little bit about their parent body which likely is.
Ioannis Kouvatsis: So versatile is one of the very few differentiated asteroids that remain almost intact from the solar system, and I say almost because if you have a look.
Ioannis Kouvatsis: Here at the image on the right disabled vesta is a little bit squeezed which is probably the result of two massive impacts that destroyed the big part of the south Pole and created these to create a shown here we are Sylvia and when, in a year.
Ioannis Kouvatsis: So verse nice thought to have formed you to rapid accretion very early in the history of the solar system and quickly melted most probably due to its short lived aluminum 26 content.
Ioannis Kouvatsis: As a result, these slides to differentiation of the body with episodic crust overlaying a depleted patriotic mantle, and I mean for iron core.
Ioannis Kouvatsis: The prison surface of Versailles is expected to consume stuff and answering volcanic terrain that has been extensively modified by impact and that's all that in that process has exposed the other like cross and possibly parts of the upper Mandel.
Ioannis Kouvatsis: As well and i'm going to going i'm going to return to impact later on in the presentation and and why they are significant part of the history of the asteroid and why they're also related to our reasons for calculus.
Ioannis Kouvatsis: So.
Ioannis Kouvatsis: I should also say he thinks about at decent general so he does have been both spectroscopy and dynamically linked to vesta, which is why birthdays also the presumed foreign body of hd.
Ioannis Kouvatsis: So he these are very interesting clan or 500 meteorites with this distinct photography photography but it's also correlated with different layers.
Ioannis Kouvatsis: On best so, for example, our diets they are ratios that contained you critical died genetic material and they represent the.
Ioannis Kouvatsis: Regular or vesta, which is the upper most layer of based on and, as you can see here from these events they have these more finer grain matrix and they also have several mineral lifting lifting and attack class we've seen them.
Ioannis Kouvatsis: Then we have you crites which are thought to have crystallized us love us on vessel surface or in solid dikes and pollutants and they can be classified as either a Celtic or to emulate rocks so hearing these two images, you have to assemble two examples on the left one.
Ioannis Kouvatsis: Is the there's a Celtic you cried which you can see that texturally is similar to at the restaurant myself, and then on the right, you can see, accumulate you crites with larger crystals that.
Ioannis Kouvatsis: comes from deeper within the crust of vesta and then, finally, we have Diageo nights which are coarse grained emulates and therefore to originate from even deeper in the crust and probably also from the upper management.
Ioannis Kouvatsis: So you can see that already the https they're quite textural different from one another and.
Ioannis Kouvatsis: It is, it is also representative of you know, the different layers that.
Ioannis Kouvatsis: So the purpose of this study is to examine the mineralogy of nwa 11 548 and we also want to locate and describe middle class that we.
Ioannis Kouvatsis: intend to target for further chromatic studies that will include argon are gone and uranium lead chronometer so the sample is a mommy.
Ioannis Kouvatsis: mommy did you cried and he was founded in 2006 in North West Africa and has a mass of 402 grams, the main mass.
Ioannis Kouvatsis: is being shared by product private collector and the cascadia meteorite laboratory at portland State University holds a 25.8 grams slice and also published in section from the same slice so we borrowed.
Ioannis Kouvatsis: To nwa 11 548 samples, one of which is a fragment that is set in an epoxy that has been published, and the second one is a theme section.
Ioannis Kouvatsis: So there have been previous studies that's if targeted middleclass to determine a potential timing of impacts and resetting vince However, the majority of our side is have focused on mineral minerals metrics and they mostly used mineral separation techniques.
Ioannis Kouvatsis: So, for example, poker 2011 studies in number of faces on https and revealed a clustering of ages are 3.42 4.1 billion years which suggested a similar age range with studies from lunar samples.
Ioannis Kouvatsis: And then, two years later candidate ally reveals ages of two periods of significant impacts at 4.5 and between 3.5 and 3.8 billion years and they did that by studying the chronology of minerals metrics and also metro melt rock of.
Ioannis Kouvatsis: hgtv then, on the other hand.
Ioannis Kouvatsis: Previous work by.
Ioannis Kouvatsis: Car straight ally of 2016 used an institute methods and focused on targeted chronological analysis of milk glass of milk glass on Howard nights.
Ioannis Kouvatsis: And they will significantly broader age ranges from 2.5 to 4.5 billion years.
Ioannis Kouvatsis: And so, as we can see here not only we observe, you know this wide age ranges of phases within at this, but they are there appeared to be differences between the history of.
Ioannis Kouvatsis: moon and the vesta and as a result, when we are trying to so we're also trying to expand our asset in enterprise as well, and I think it would be an interesting discussion as to what these differences disruptive differences between ages.
Ioannis Kouvatsis: On class from moon and vesta mean also you know when completed, considering the broader the broader context, the inner solar system but barbecues.
Ioannis Kouvatsis: So I like to say, also a few things about impact what's their.
Ioannis Kouvatsis: guns and how also they relate to the study of calculus so inbox are important solar system processes and they are recorded and preserved as.
Ioannis Kouvatsis: shock metamorphic effects in many meteorites, which also includes https and the result in deformation effects in rocks and minerals, for example, we can have bridge creation.
Ioannis Kouvatsis: We can have formation of medicine high pressure temperature high pressure and temperature polymers and i'm going to show some examples of that on the following slides.
Ioannis Kouvatsis: But before we go into that I would also like to say a few things about how these different processes.
Ioannis Kouvatsis: react, or how how actually they they are combined with you know the middle class that will live.
Ioannis Kouvatsis: On our meteorites So here we made this gets while thinking about how Mel class or forms and I thought it would be very interesting to share it here, and maybe also.
Ioannis Kouvatsis: This spark and discussion at the end of course you know that.
Ioannis Kouvatsis: It is not up to scale, so I just thought that at this time, its scale is less important it's more important to focus on, you know the different things, for example, the melt rock fragments and you know these.
Ioannis Kouvatsis: Massive richie did you cry or these also very large biological age, because these are the faces that.
Ioannis Kouvatsis: We are going to study and then try to infer the relationship with impacts, so if we assume that we have.
Ioannis Kouvatsis: The surface of an asteroid let's say, for example, and then we assume that we have an impact at the surface.
Ioannis Kouvatsis: Then, this will create a creator and also an amount of melt, which is also dependent on the size of the Creator, so the practice itself could also produce ejecta in the form of these melt Pharaohs and also some personality you cried fragments.
Ioannis Kouvatsis: which could then form a pile of material.
Ioannis Kouvatsis: shown here, which then develop into a bridge at you cried where we can also have some some burial which, which also you know could probably do some metamorphic some metamorphosis on on the.
Ioannis Kouvatsis: Ukraine, and of course this is rather simplistic approach, this is this might be a bit more complex, but I think these kind of you know, represents how things within Max world and then.
Ioannis Kouvatsis: This impact with also create shock and then increase in temperature, which would then form these you know shocked and reduce the light pleasure places and could also form some shopping used.
Ioannis Kouvatsis: middle class, and then we can also have a secondary impact that.
Ioannis Kouvatsis: Could fragments the the melt rock that crystallized after the let's say the primary inbox and this could probably form a second generation of.
Ioannis Kouvatsis: Mel class that could have different textures and composition composition visions when compared to the previous one from the primary inbox so when we consider.
Ioannis Kouvatsis: What class ages ages mean, I think it would be very useful to think about the broader context about you know how they form, and I also think that this will help us to drive better conclusions about what their.
Ioannis Kouvatsis: Data means in terms of in terms of you know.
Ioannis Kouvatsis: and
Ioannis Kouvatsis: Going into the methods so so far we have used optical microscopy observations using these eyes actually imager.
Ioannis Kouvatsis: at the University of Alabama and we also did some preliminary.
Ioannis Kouvatsis: scanning electron micro probe on the sample of the Obama analytical research Center as the way for general high resolution imaging purposes, and also to locate and examine the textures of.
Ioannis Kouvatsis: Mel class within the epoxy embedded sample and I would say, also a few things about these two methods in the next slides because when we're trying to locate.
Ioannis Kouvatsis: These middle class, sometimes it appears that the SEM images are make are easier to you know detect these men helpless.
Ioannis Kouvatsis: So, moving on to the observations, so the thing section so abbreviated you cried which contains several music and and melt brejcha class which is shown here in figure one.
Ioannis Kouvatsis: um So here we can see the boundary worthy these inbox male ratio class these, and we have you know this crystallized materials here and we'll share the pre.
Ioannis Kouvatsis: From minerals, then the most common minerals are pirates and in place and middle class, they open up your dark in color so most of the time they're.
Ioannis Kouvatsis: black or their dark brown or Gray in playing polarized light, but as i've said before it's they're not very they're not always easily distinguish distinguishable when using come across will be so that's where.
Ioannis Kouvatsis: scanning electron microscopy comes in and help us to identify how you know the smell test.
Ioannis Kouvatsis: So cheer is an example of mentors that were found in in our specimen so on the left, we have the blame for life polarized slides.
Ioannis Kouvatsis: image of nwa 11 548 and and you can see, we have a few minutes Plus, you can see these to appear black in color and then we have another one which is light Gray and.
Ioannis Kouvatsis: The point I want to make here and I will show you in a couple years later, a few minutes is from SEM, it is not always easy to find this melts especially.
Ioannis Kouvatsis: When you have a complex sample which is you know break created, which is the timer for some Jeff all these different minerals and phases and us so upcoming microscope is not always you know, easy to distinguish these Mel class.
Ioannis Kouvatsis: here's another example, so this one, usually the meltwater cure find going to crystallize materials in sizes of equal or list 200 microns but this one is a rather large one, and you can see that you know they have this very fine grained.
Ioannis Kouvatsis: crystallized metrics and they also have some.
Ioannis Kouvatsis: mineral class within them, that also show some kind of shop shop features within them.
Ioannis Kouvatsis: So, moving into the SEM images, so this is the.
Ioannis Kouvatsis: This isn't an SEM image which shows a middle class here outlined by these red dust line, and there are so many plants, they have.
Ioannis Kouvatsis: Some different they showed different textures sometimes so some of them shift different phases within within them, which are probably due to reconcile ization and impact submit our vision and, in our case, we have again these refined grains Mel Mel class.
Ioannis Kouvatsis: which shows the minute we chose mean our actual task within them, and you can also see this particular one we have this very brighter phases, which are could be some ironical metals or I believe it would be phosphates as well, for example.
Ioannis Kouvatsis: A minute so.
Julia Cartwright: yeah Thank you.
Ioannis Kouvatsis: So someone's last also so different phases, again, and you can see, in this particular SEM image, you can see that we have this.
Ioannis Kouvatsis: selfless here, which shows these crystallized texture and, again, I just want to point out that SEM sometimes it's much more reason to the text middle class with because.
Ioannis Kouvatsis: I guess it's the Gray scale that helps the Ai to detect this middle class, so it is really a very helpful technique in our effort to locate the middle class.
Ioannis Kouvatsis: And I will also like to briefly say a few things about you know other minerals and pleasure places that also be.
Ioannis Kouvatsis: able to record the inbox so share, for example, who have applied to place, and you can see that.
Ioannis Kouvatsis: it's always this recrystallization and it would be very interesting if we can also include some some logical is, for example in our research and see how they record impacts one converts to math class.
Ioannis Kouvatsis: So for future work, we also like to include some ultra pro micro analysis measurements because.
Ioannis Kouvatsis: we've already observed that these middle class have different textures and then we also like to see if they come in different competitions and if there is a correlation between the textures and the composition and and.
Ioannis Kouvatsis: Another important thing we want to do in our future work is to analyze selected middle class using an institute ultraviolet laser ablation micro probe to study the Oregon Oregon chronometer and to actually study the resetting ages, and this will be done to to disturbances from thermal.
Ioannis Kouvatsis: shock Madame efficient processes that can lead to loss of are gone and therefore reset.
Ioannis Kouvatsis: The clock and we want to combine them with also with high precision institute again I crystallization ages, using the uranium lead chronometer.
Ioannis Kouvatsis: Using a secondary I knew there's mass spectrometer and what we want to achieve achieve by combining these two methods is First, we want to constrain the crystallization history of middle class, first by using the random lead.
Ioannis Kouvatsis: And then Second, we want to constrain the history and the extent of.
Ioannis Kouvatsis: Impact events by measuring disturbances in the organization system, so we have this to our other different chronometer.
Ioannis Kouvatsis: One you know studies, the Oregon Oregon which as because it's being a noble gas when you have a certain event it's diffusers i'd say more easily so and then we can also have a more sturdy chronometer, such as the uranium lead.
Ioannis Kouvatsis: which could probably gives us give us some different or some some some other results in order to combine with the Oregon Oregon and get a better understanding of for the crystallization history and also be sure in the extent of impact events on vesta.
Ioannis Kouvatsis: And with that, I would like to think we would like to thank the cascadia meter a laboratory at portland.
Ioannis Kouvatsis: State University or providing the samples of nwa 11 four or five, eight and we'd also like to thank.
Ioannis Kouvatsis: The staff what ASEAN QA for their systems with the sm SEM emerging and also, I will do for here SEM emerging contribution, so thank you very much, and if you have any any questions i'd be.
Ioannis Kouvatsis: glad to answer, thank you.
Colin Jackson : Thank you Jonas.
Colin Jackson : let's open up the floor for.
Colin Jackson : For quick questions we're up against time a little bit, but if there's a question, we can slide it and.
Colin Jackson : I guess my my thought is for.
Colin Jackson : Some of the larger impacts that vesta has experienced.
Colin Jackson : Would that you'll be a sufficient thermal pulse to completely reset the body for a system like Oregon Oregon I don't i'm trying to imagine you know I guess how much of the earliest history of vesta has been lost.
Colin Jackson : It from the perspective of Ireland Oregon dating.
Ioannis Kouvatsis: Yes, that so that's that's great question and I think this will also be a very big part of the discussion when we get in our data because of this, the Oregon Oregon data relates quite heavily to how.
Ioannis Kouvatsis: know how the magnitude of an impact, so I guess the, the higher the magnitude of an impact the I just be easier, the Oregon losses, so I think the hard part would be to try and get a record from the lower marketing inbox because maybe they are not producing you know the sufficient.
Ioannis Kouvatsis: Short conceit sheets, in order to reset our the chronometer the cake local in selfless and also, it would be very interesting to see you know how different minerals react, you know different invites.
Colin Jackson : Definitely dope think, thank you very much for your presentation let's let's let's move to our final presentation in the session.
Colin Jackson : The author is David King and the title is trans Alabama super bowl it to December 5 1999 quarters.
David King: Okay, can you see the screen.
David King: Are you, seeing that.
Colin Jackson : Come and get it.
David King: looks great.
David King: So.
David King: As i'm sure most of you probably know.
David King: Their bowl on Defense globally, all the time of various magnitude, so this is a map of some of the smaller objects that have disintegrated in nurse atmosphere over a 10 year period that I just grabbed off the web.
David King: So on December 5 1999.
David King: There was a fairly large eliminated area in the southeast caused by a bowl and an inner depths here.
David King: and
David King: traversed sort of Northwest southeast it happened at 430 in the morning central time.
David King: It was witnessed by hundreds of people.
David King: Who called into fire departments police departments emergency management thinking that aircraft it crashed or something terrible and happen um it was saying, as far away as the Western panhandle Florida, all the way to Atlanta.
David King: This the Department of Defense issues press releases after events like this, and so their press release, which came out in March of the following year, said that the object energy atmosphere here passed over the town of good water and that the elimination ended here.
David King: This is announced to 74 kilometers that's 3223 kilometers it turns out, this is is wrong.
David King: We.
David King: collected information from a lot of different eyewitnesses was still I spent time talking to people and reading.
David King: reports in the news and.
David King: On the Web i'm a geologist it was an eyewitness near Athens Alabama saw on the object moving straight toward.
David King: The waning crescent moon, and so, if you go to the naval Observatory web page and then calculate and as and that's about 104 degrees it's it's he's se as of.
David King: These are some other observations from a land surveyor and auburn.
David King: den Jones just in Athens, a store owner and we a gaff and and all these people reported on.
David King: East southeast.
David King: trajectories, and so the as strange from 97 215 degrees that's nothing like with the Department of Defense.
David King: reported so waiting to the conclusion that the flight line was more like this, rather than a flat line like this, which is what the Department of Defense chest it on what you're seeing here as amount of different towns, the latter coating is over here, for example, PRS prep mill and.
David King: PC is pell city and he is he in Seville and l is lay down these are all towns in Alabama for the most part, where people saw this the being dots lots of people.
David King: The smaller and dance not so many people.
David King: According to news reports and according to.
David King: What we were able to discern by people contacting us I witness interviews.
David King: So all the people in this area, saw it.
David King: But some people also heard it so there's lighter shaded area or people who heard.
David King: sounds from this and then the darker shaded area in the Center there are people who felt I felt vibrations they felt i'm shaking.
David King: day they actually were under the fly on so we came to the conclusion to fall in line with something like this i'm a few years after we finished this study, which came out in in eos transaction that 2003 I learned on an old childhood friend who had a.
David King: vacation house and right under the fine line is actually knocked off his porch and of course there's no record of that so I just got this picture from the Web just give you a visual there but anyway.
David King: So we're trying to estimate velocity is using a surveillance video from a store in Alabama.
David King: The general duration of the elimination on that video was 3.4 seconds, and if you divide that by her estimated flight path you get 16.4 kilometers per second.
David King: We also use the movement of shadows from Poland that video and we got an estimate of 18.3 kilometers per second.
David King: This is how we did the estimate, there was a moon the cast a faint shadow that you can see, and then, when the ball light of period there's a bright.
David King: there's much brighter so you get a farm all shadow on the other side, then, is a fireball move past the shadow moves so we're able to time that and that's how we got that that estimated velocity.
David King: Of shatter move on this is the general store in.
David King: Alabama it's on my mind caper tunes kicked in store, so we got cuz w it's right under the flight line there, this is the main highway looking south.
David King: Africa it's out now state highway 29 this road has an azimuth of about 97 degrees it's almost exactly parallel to the flight line of looking at the front of the store.
David King: That there is the video camera that captured to the video that we're going to take a look at some outtakes there's a hitch post that you can see in the video.
David King: Back in 1999 I was an ice machine right there you'll see that in a video, and this is the Paul with the sign.
David King: So from the video this is suggested to beginning of the there's the pole with the sign on it there's the ice machine and there's that hitch post, and this is the Alabama highway 29, so this is at zero seconds, this is.
David King: 0.7 seconds, you can see the illumination from the ball light is coming under the overhang and it's eliminating these objects that are sitting on the front porch.
David King: Now they're at 1.4 seconds, the cameras basically being overwhelmed by the light of the bowl line which is passing right over or dufka in it to 2.1 seconds.
David King: it's beginning to move to the south and you see that the these things, and now i'm a bit of shadow and the light is coming from the south.
David King: And then it starts to darken 2.8 seconds, but the bowl is past we've got going, you can see these buildings are eliminated but backlighting, and now it goes at 3.5 seconds back end basically shadow.
David King: There was an audio recording that accompany this surveillance video and you hear a noise that sounds like a distant rifle shot.
David King: At 83 seconds after the illumination ends and then you hear for an additional 91 seconds along unbroken thunder like noise that sort of tapers off in its intensity.
David King: So just to remind you, where we got was was right under the flight path so you saw the light from the object pass and then the sound.
David King: is catching up with it sounded a much lower than.
David King: elimination what, so this is a generic on graphic of meteor dynamics I got this from mark freeze when I attended to short courses met sock a few years ago, the objects coming into the atmosphere, you get some noise from it, starting to enter.
David King: In the light is.
David King: The light is constant but you'll get a white flash if there's a breakup of an interestingly, none of the eyewitnesses described in the night white flash so maybe there wasn't breakup of it.
David King: Anyway, this is probably the origin of the site boom if you figure the speed of sound and air.
David King: Get.
David King: 29 kilometers away for the initiation of the sonic boom and the rumble sound on a little bit older greater distance sound and flight i'm so i'm so it it's eliminated through this path, and then it slows down to his interest it's dark flight.
David King: mode is all meteorites dude and and basically drops at a fairly low velocity and then plops under the ground so somewhere landed.
David King: A little bit want us to real town, we never were able to find unfortunately the.
David King: The place where it actually landed on the surface.
David King: So this is a weird thing i'm in harper's ville there was there were some Chinese ground fires and we went up and examine these are three burned elliptical areas.
David King: The as most of these ellipses were between 90 and 110 degrees, which is parallel to the line flight path we interview the residents who lived across the street from this one burn patch and they said well the fires began when we saw them light in the sky, and I saw the light.
David King: The harper still fire department call log shows incoming calls about the fires within three minutes of the phone lines passage and satellite data shows no light in the area and that day so.
David King: I don't think, and I would not say to you that meteorites typically start around fires in fact that's very hard to conceive of there's no time for.
David King: Multiple material to land on the ground so something.
David King: Even this is an incredible coincidence or something's going on there and then, if you Google ground fires and.
David King: meteorites you'll find a reports of this on the web so maybe something's going on there, but harm facility is slightly off the flight path so I just point that out.
David King: On there been other ball lines and alabama's history, these are the fallen meteorites that pinpoint of the lights i'm sure there is no fallen meteorite but.
David King: it's interesting that that many of them seem to be.
David King: November to.
David King: January I guess that's a time when people.
David King: can see stuff like this in it in the lengthy night sky, this is a silicone meteor is is famous for having cause the human injury and.
David King: Unfortunately that's the injury Asians is hodges and you see in the picture came through a roofing and hitter in the hip.
David King: So it's interesting to note that forms of seven of these bullet events have occurred within eight calendar days and two on the same day.
David King: As meteorite in 1868 and the bowl wide event.
David King: In 1999.
David King: But in 2019 guess what i'm exactly the same day comes, another firewall in this time going in the opposite direction.
David King: or Alabama so I know there's a bull's eye painted on Alabama for early December.
David King: So, like said we didn't get this published in eos and some have to say that tracking down things about this meteorite one of the more interesting field projects, I worked on here in the state of Alabama run into contact with a lot of.
David King: local residents in one area in.
David King: Their life stories that I would never otherwise have an experience.
David King: i'm gonna stop sure, and if there are questions on the happiness.
Colin Jackson : Thank you, thank you very much, David let's open the floor for questions on the presentation.
David King: So while people are thinking that we put the word out on local media and talk to TV and radio and.
David King: The papers and anybody knows anything, please contact us and I was hoping that somebody would say well there's this plenty hole in the roof of my barn or you know dent in the car the awesome there last week, but unfortunately it just never turned off.
David King: and on if you know mark phrase or not, but he.
David King: got into research using weather radar to track meteors to the ground.
David King: he's been real successful so we went back and looked at the archive weather radar.
David King: From 1999 understand you could just barely see it, it couldn't be trying to the ground and.
Colin Jackson : We have we have a question from the audience from from hazel Gordon would you prefer me to read a hazel would you want to unmute yourself and ask a question yourself.
Hazel Gordon: Surely i'm i'm certainly ignorant of the entire field here and I was just wondering how many bullets have been retrieved and, if so, have the origins been determined from you know different.
Hazel Gordon: Extra planetary bodies.
David King: um where they're going to al Alabama those meteorites that you saw and planning their those.
David King: According to the meter I can longer than other known ones where there was a bowl line flash and then they found the object now there's been the way I found in the soil that no one.
David King: saw fall, but those ones, that was a flash and and somehow that were able to find it, which is really lucky because it's very difficult to do that.
David King: People say, well, it is it fell right right over there, but then it's you know kilometers away or 10s of kilometers it's very deceptive, so this weather radar method has has allowed.
David King: Mark phrase and others to track meteorites down to the ground and it was one that fell in the bank and forest in Alabama on a few years back, and he knew exactly where it was he trying to get it in the forest ranger wouldn't let her have it, but.
David King: it's rare it's very rare and of those meteorites they're all different types so it's not like one object is working up and we're getting a little piece of it or once in a while on summer congrats on.
David King: stony island irons, in other words, God knows more about me right Thompson.
David King: isn't they're not from the same parent body as well.
David King: So.
Julia Cartwright: We can look at these things we can we consider the compositions of these meteorites and we can try and do comparisons with.
Julia Cartwright: spectroscopic data data, but so like remote sensing data collection space and try and compare what we're seeing with.
Julia Cartwright: The compositions of the stuff that we can recover so that's one way that we can be like maybe this and maybe that maybe they come from the same place.
Julia Cartwright: that's when we can do it the other way is.
Julia Cartwright: As you seen the radar data and whatnot you can track these things coming in and sometimes you're able to actually try and determine the path going out as well, like to try and backtrack where they've come from.
Julia Cartwright: And there are some models that have have done, I mean it's a little bit difficult, you know, because you have to rely on the data that's collected when the bird light falls.
Julia Cartwright: There are a lot more cameras now watching the sky so we're able to triangulate things and observe angles properly and figure out how things are coming in, but.
Julia Cartwright: You know 20 years ago if you've got one camera bring watching something come in it's very difficult to determine.
Julia Cartwright: exactly where it's coming from, especially if it's coming towards you you're like where does it come from you know it what it can be, it can be tricky but there's a lot more work being done now, with cameras with.
Julia Cartwright: Especially if they're not necessarily and in a triangle formation, where you can you can work with the light and you can work with a sound to figure out.
Julia Cartwright: Precisely the speed and that can help as well and different materials and have different speeds, so that that that can help try and figure out what it might be, because sometimes this stuff doesn't even get to the ground, so we see it, and it totally.
Julia Cartwright: kind of not quite evaporates but you know exposing to lots of different things and vaporizes I guess.
Julia Cartwright: We can't always figure out what it was, I thought to help them.
Hazel Gordon: Yes, thank you very much.
David King: One of the interesting things that I mentioned, was it to know and reported any light flashes which would be impeccable events, and if you.
David King: Would watch that whole video only took out takes but there's no changes in illumination so it may be that the thing actually fail in its entirety.
David King: would be really nice fine, but unfortunately never returned.
Colin Jackson : On along those lines Steve Godfrey has a question would you would you like to read it seaver you want to unmute yourself.
Steve Godfrey: Well that's fine i'm also completely ignore the field, although it's so fascinating but those fires seem like an astounding coincidence.
Steve Godfrey: And i'm just wondering if you've used any high sensitivity metal detection or ground penetrating radar to look for disruption in the surface i'm going to type it up beautifully to do that, with all that crush burnout has anyone ever tried that.
David King: And don't know about that, but it's we didn't expect to find meteoritic to bring you there.
David King: There are TV news videos of people walking in and looking for pieces of media right but I didn't think we would find it there, I think that's.
David King: If those fires or religion, I mean you're right, it is a, it is a electro magnetic transfer of energy.
David King: instantaneously from the object to the ground that starts the fire because it incandescent piece can't fall down it's not going to transfer enough heat energy to do that and it didn't hit there, so I you know.
Steve Godfrey: I don't know It just seems like an intriguing possibility of a that's far that's just the style of me coed steps and he say so i'm so the energy transfer occurred and.
David King: I don't really believe it, but I mean it's there so i'm important.
Julia Cartwright: I would concur with David that I think it would be very unlikely for a fire to start from something like a crater impacts and like that.
Julia Cartwright: yeah I mean, especially with the flight path like if the front of the fragments you would expect it's anything foul if it would have fallen much further away from that locality.
Steve Godfrey: idea, you know that's.
Steve Godfrey: that's quite a cluster.
Julia Cartwright: But it could also be the fact that I mean if this happened at night and people were alerted by the fact that there were bright lights in the sky.
Julia Cartwright: Maybe after that they were like oh wait this things on fire, like if they might they might not realize that something was on fire and the bright lights kind of yeah and they were like oh no this thing you know.
David King: Maybe family that we interviewed the light from the ball I woke them up into the window and they went outside to see what's going on, and then they saw the fire, so I.
Steve Godfrey: Think.
Steve Godfrey: yeah it's fascinating.
R. Scott Harris: yeah David.
David King: Yes.
R. Scott Harris: When when you said there's there's no lightning we were where you are mark able to getting archival actually lightning trackers or is that more activity.
David King: yeah I couldn't attend to that company that the TV stations use that the archives lightning strikes by satellite, and they said no, not an Alabama the closest like Cuba or something so and I gave them the time frame and.
David King: They also take satellite images it's certainly a time intervals, but they missed that little window and now just came in so there's no photograph from space, but.
David King: yeah I did a lot, a lot of research i'm trying to figure out could there be some other reason why there was a fire there.
David King: and
David King: it's not aligning there was a weather front movie in that eating some clouds in North Alabama moment.
David King: It was.
Colin Jackson : We have a question from mark boy.
Mark Boyd: yeah thanks so much for the presentation David it was really interesting I was just wondering whether maybe not with this particular by light, but.
Mark Boyd: Other ones in general, maybe that we have more.
Mark Boyd: CCTV image of can you start to reconstruct any kind of atmospheric entry parameters I don't know whether maybe the brightness of the Flash can tell you about temperatures reached or anything like that.
David King: They be and I haven't kept up with this field since I.
David King: Did this back in 2003 that I know and Julie was saying is, if you have multiple cameras and there's there's much more remote cameras, now that weren't so.
David King: And meteoritic some planetary science there's several papers that have come out in recent years about they've been able to figure these things out because there's lots of cameras but yeah back in the day I mean, I have the old vhs recording somewhere.
Mark Boyd: The.
David King: store owner gave me.
Like.
Colin Jackson : Are there any more questions from the audience.
Julia Cartwright: If.
Colin Jackson : If not, I guess, so I will thank everybody here for attending and it's been a great session and we've all learned a little bit about what's going on within planetary science here in the southeast so thank you have a good rest of your day and we'll see each other later oh.
Julia Cartwright: yeah thanks so much thanks for attending. 1266