Our galaxy we call the Milky Way

space cowboys is brought to you by people like you on patreon welcome back to the fourth episode of space cowboys yeah welcome tice and welcome herbert yes that's us yes that's us and we have here anthony brown from light and observatory welcome thanks yeah thanks for talking to us i want to go straight to the story of the week because it's literally happening right now before me so i'm maybe people can hear this but right now i'm looking at a blue origin launch um it's launching right now it's launching as we speak here that's beautiful to be live streaming but we are yes yes we're working on a live stream just like blue origin is uh but we're not for our new for our new listeners we usually start with the story of the week but this is happening as i'm looking at it so that's another lift off we have yeah it's it's another lift off so it's it's the blue origin is the um the company the space company of jeff bezos the um the ceo of amazon of course and uh it also has uh hear me it also has a rocket that that flies out and lands back on earth just just like spacex yeah and for some reason like whenever it's this comes up i'm like hey that that it exists and it works yeah like right now it's like a blue origin launch okay now i'm looking at it like hey it hasn't exploded it works it's a little odd it's a little odd looking i think actually launch a rocket yeah exactly don't you think it's a little odd looking it looks different from other rockets that i know and and well more stubby stubby right yeah yeah not very aerodynamic uh no do you know a lot about rockets anthony not particularly but for aesthetics at least okay but this one it is a special one it's doing a suborbitals flight right uh yes this is uh it's not going going into no into orbit no uh it's it's suborbital and it it is deploying something um i would have to look into it actually the fun so that's one of the funny things i i sort of like quickly tried to see okay so what's up with it where are we what are they doing yeah i land on a 404 not found page for the news release it's it's a little odd it's we can put something on the show notes yeah yeah so if people are interested go go look at what blue origin they have they have cool stuff but you never really know what what what they're up to right there's well for this flight there's a page and it sums up about eight experiments that are on board okay and i couldn't uh reproduce reproduce this now but uh the the information is there yeah and they have a couple of experiments for various various companies and and institutions in the states but in general the shine on blue origin is less than spacex right don't you guys agree maybe they do less pr or something but of course they do suborbital flights they don't dock into the space station they don't bring astronauts up they don't do supply missions you know so it's it's definitely a bit less sexy yeah i guess are they a little bit behind spacex i wouldn't know but probably yes but yeah or aiming for a different market i guess as well yeah space tourism tourism yeah they said that that's what they do long term yeah this year uh supposedly the first people are gonna go up on a rocket like this so on a new shepherd i'll believe that when it takes place yeah exactly we'll check back in yeah right around then um anthony what's what's your story of the week yeah so uh i'm it's a bit strange i'm a professional astronomer but yesterday no two days ago in the morning i saw my first full lunar eclipse your first yes your first lunar eclipse indeed uh of course i've had uh opportunities before but i was always either asleep or it was cloudy so this was the first time it was i was up in time to see it and it was a very clear sky so yeah it was spectacular really beautiful right yeah absolutely so such so weird looking that red moon yeah over over over the city it's beautiful personally um i thought it was a bit overdone in the press oh the wolf red yeah the super blood wolf moon or something yes meaning just another lunar eclipse in january and the moon is slightly slightly larger than normal yeah yeah i know one of my friends disappointedly said i'll be dead by the time of the next lunar eclipse and i said well this that's because this is super blood wolf there will be more in in our lifetime yeah yeah i mean you gotta amp it up again make it up again make it up again make it up again make it up again make it up again make it up again make it up again make it up again make it up again yeah and herbert well did you know i mean by the way uh anthony amazing that you finally saw it may you are you've had decades of chance to yeah because the eclipse is not very very special is it no it's not a rare uh event all right yeah that's it's just what happened yeah i mean i have I'm not an astronomer who goes out regularly observing with a telescope. I don't have patience for that. And here it's too cold, basically. Especially right now. The viewers at home can see the snow outside. It's terrible. Well, well, well. It's barely freezing. Come on now. I have my thermo underwear on. I hate this. I don't. I have this sweater and I'm considering taking it off because it's too hot here. It's a little hot in here, yeah. Herbert, what's your story of the week? Well, my story is that I'm going to add a bit to Anthony's story because I saw this news item on space.com and it told me that during the eclipse there was a freaking meteorite impact on the moon. What? And it was photographed. Yes. No way. I have it here on my screen. I'm going to lift up the laptop and you can see it. Let me. Well, okay. Here with the arrow. Yeah. And it's also. Wow. The larger picture somewhere around here. That's crazy. And space.com mentions a video that's supposed to be there on that page, but I can't find it on that page. And I'm wondering if that's something to do with my browser settings or something else. But there is a photograph in any case. And so many people were photographing it at that moment, I guess. Yeah. The chance of catching an impact, of course, is very high during a lunar eclipse because everyone is photographing. Yeah, exactly. I mean, these things do happen. They do. Of course. And impacts have been caught before on photographs. It's funny. This really makes it unique to me, at least. Yeah. It suddenly is. It was a very unique super blood wolf. The wolf smashed into the. It's very difficult to say it all in one go. Exactly. Yeah. Yeah. The wolf exploded. I thought this makes it really interesting. It does. Yeah. Yeah. We'll put it in the show notes too. And not scientifically speaking. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. In show notes. Yeah. So very, very cool. But that's what we're going to talk about today. We're going to talk about Gaia, the mission by ESA. Really great mission already going on for five years. And we're going to talk to Anthony Brown from Leiden Observatory. And you are not only a researcher there, but you're also the head of the consortium that handles all the data. Yep. And how big is this consortium? Consists at the minimum. moment of about 420 members and they just do the data processing yes so 420 people yeah are doing just the data processing of this one mission which is huge uh yeah it's uh it's probably one of the biggest astronomical consortia for space missions out there but in the future missions like euclid plato will have even larger consortia that's already the case also ground-based large surveys like the large synoptic survey telescope which is being constructed in chile right now they will image the whole southern sky every three days more or less the whole southern sky will be a huge consortium both processing and analyzing the data so this is increasingly becoming normal in astronomy to work with these large groups because the instruments and become more complex more complex data much more data is being gathered and you just need more people to handle it yeah first about the gaia mission what it tries to do um it basically tries to map the milk our galaxy the milky way that's right it's it it's it you can't do it all but at least it's trying it's the first time attempt to sort of start cataloging the entire milky way so that we know how it works so that we can get to know the stars see where they are how the milky way rotates am i saying this all correctly yes that's uh that's correct so the the the main aim of gaia is to collect uh distance measurements to stars so of course we know where each star is on the sky that's that's a relatively simple part of the measurement and then by measuring repeatedly the position of the star over the sky over a period of five years we can actually see it move and the movement consists of two components one is the fact that a star is actually moving through space so it's moving also with respect to us and that means that it's makes a tiny displacement on the sky every year which you can't see with the naked eye it's too too small but you can measure it with something like gaia and the other motion is the star appears to make a spiraling motion across the sky due to the yearly motion of the earth around the sun correct parallax yes that's the parallax so so i get this correctly because i i've seen multiple sort of like visualizations of this um a star moves through the milky way right so all together in this big whirlwind of stars we go around the sun but the sun also goes around a supermassive black hole in the milky way and then because all the planets move around the sun the sun gets wobbly it goes into like almost like a spiral so that's not the kind of motion so i'm asking i'm not telling you yeah no the point is that the uh because we are making a yearly motion around the sun if you imagine that you're looking at a particular star let's say that light there in the in the ceiling and if you walk around the room the position of that light if there were a background if there were no ceiling the position of the light would seem to change a little bit simply because you're changing the position of the light so it's a perspective effect so you're circling the sun like this i mean people can hear me yeah yeah the star makes a little circle on the sky and uh the combination of your motion around the sun and the motion of the star through space uh makes it look like it makes a spiral motion so this circle being stretched out and that's another clue to the distance of the star the parallax is a direct measure of the distance to the star correct so um is there some bigger question behind all these measurements that gaia does um or is it simply an idea of we want to know what is where and how it moves in all of the galaxy certainly we would like to catalog everything because that ultimately is the basis of all the understanding is knowing where things are what their characteristics are but the real motivation is that we think we we want to understand how our milky way came to be so we know that the milky way consists of a thick central part which we call the bulge which is also where the the black hole sits in the very center yeah and the bulge is surrounded by a disk of stars and it has very nice spiral arms in the disc if you look at it from above and this whole system is surrounded but by what we call a halo and a halo is consists of very old stars also globular clusters can be found there dwarf galaxies etc and the question is how did this come to be why does the milky way look the way it does today um and we think this is that the galaxies build up gradually over time so that they start out as small entities that merge together because of their mutual gravity and then slowly you build up bigger and bigger galaxies okay see evidence of that in our Milky Way well that's that's the point so we the only way we can see the evidence of that is by actually measuring the distances and motions of stars you cannot simply take a picture of the example the remnants of a recent merger between the Milky Way and a smaller Galaxy are you really need to know the motions of the stars because you can group stars together because they're all moving in the same orbit and that reflects in particular characteristics of the of the measured motions so measuring these distances and motions it allows you to get the get the real 3D space motion um that allows you to group the stars in into different original building blocks of the Milky Way and then the other thing that Gaia does is it also gathers information on the stars themselves so it measures their colors with high accuracy and it also measures how fast they're moving towards us or away from us that component of motion cannot be measured by looking at the positions of the stars that you have to do that separately using the Doppler effect in the on on the spectrum of the of the stars um and and and the measurement of the colors serves to characterize the star so you can then figure out what is the temperature of the star what is luminosity what is the chemical composition or at least a very rough indication of it okay and ultimately this this kind of information together with the distance can be used to figure out how old stars are and what we want to do is we want to build up the history of the Milky Way and of course we need to know how all the things are you need to know how we need to know how old things otherwise you cannot do any kind of You need to know how deep down in the layers. Milky Way archaeology. That's a niche. I remember a satellite that did more or less the same. It was called Hipparchos. Yes. Hipparchos? Yes. Also by HESA? Yeah. Yeah. And it was somewhere around 1990. Is that right? Maybe the 80s? It was launched in 89. 89. Right. And this was a first attempt to map the Milky Way. That was a great story because I wasn't there when it was launched, but I did visit Kourou in French Guiana when it was built up. And so I followed this project. And when Hipparchos was launched, it got stuck in the wrong orbit. Oh. And somehow they managed to get all the mission objectives done. And I believe… They managed to achieve even more. Yeah. Can you tell us a bit about that? Were you in astronomy at all when this happened? I started studying astronomy in 87. So just before Hipparchos was launched. I do remember one of our staff members running around very grumpily after launch because of the wrong orbit. Yeah. And so what happened is that Hipparchos was supposed to go in a geostationary orbit. Yeah. And it got stuck in some ellipsoids. Elliptical orbit. Yeah. It was first put in an elliptical transfer orbit. And then the rocket engine that was supposed to fire failed to fire. And so it got stuck in that orbit. Now, this was not in principle a problem for the mission because all you need to know is the exact orbit, which you can calibrate from the mission data itself. But the fear was that because Hipparchos was going through the radiation belts every day, every few hours in fact, that it would be damaged so quickly that the mission would simply not… not run long enough. Now, that in the end turned out not to be the case. And indeed, they managed to do a factor of two better than what they promised originally in terms of the precision that they achieved. And so Hipparchos measured the same things as Gaia. So… Less accurately, I suppose. Parallaxes and proper motions less accurately. More 90s. And for about 100,000 stars. And at the time, it was a huge jump because we had… It was. …direct distances measured. And for a few thousand stars maybe, and Hipparchos immediately added a factor of 10 and with incredible precision at the time. And Gaia is now going a factor of 100 better than Hipparchos in terms of precision and a factor 10,000 more stars because we're well over a billion stars. One billion stars. I saw the figure somewhere in a publication that I read. It was 1.6 billion, but it was down to the last digit. Yes, we track every star. You have an exact count. There's some exact count. And I forgot to write it down, so I can't quote it right now. Do you know it by heart, the number? No, not by heart, but perhaps I could… You're going to look at it? Yeah, look at what the… Do you have a live app for that? There is actually a Gaia app. Really? Yeah. It doesn't tell you, I think, what's exactly in the catalog, but it tells you how much data has been downloaded and what the mission status is, et cetera. How many stars in the Milky Way, you think? How many stars there are in total in the Milky Way? Yeah, sort of. Let's say 200 to 400 billion. 200 to 400. I mean, that's a factor of two uncertainty. Yes, we don't know it much more than that. This is a combination of uncertainty on the total mass of the Milky Way and on how the mass is distributed over the various stars. If you have lots of small stars, of course, you have more stars than if you have lots of massive stars. And so Gaia has about 1.6. So not even… Not even 1%. Yes, that's correct. And it's been looking for five years? It will come up to five years of observations in July. But the length of time doesn't increase or decrease the number of observations. So we observe everything that we can see out to a brightness measure called magnitude 20. And this is about 800,000 times fainter than what you can see with your naked eye. And we simply measure every point source in the sky out to that limit. And that will always stay the same. So we don't go any deeper because we measure… So the 1.6 billion, et cetera, et cetera. Yeah, look it up. Yeah, it's the same. These stars will be followed for the next years to come and no other. That's correct. We keep following basically the same stars. I think it will stay the same. The number will stay the same. Yeah. I mean, it's such a huge number. It's almost insane. It's incredible. Yeah, that even just the undertaking itself, let's just map it all. But the good news is there's still room. There's still room for improvement for next mission. Yeah, yeah. That's true. I'm already thinking about the next mission. There we go. There we go. 1,692,919,135. That's the number. Wow. Sorry, one point. Learn this by heart. Yeah, 1,692,919,135. That's a lot of stars. That's so. But it's only a fraction of what… Yeah, it's going on. And what's all the other things that we're seeing? Red color, blue color. So that says something about its color, right? That you also know that. Yeah, so if we go through the various circles. So the total catalog is about 1.7 billion stars. That's this here in the blue. And for those stars, we know the position on the sky to very high accuracy. And we know their brightness, the apparent brightness. Okay. So that's the basis. That's the basis. That's what you would call a sky map essentially. Yeah. Now, this orange circle over here represents about 1.4, well, 1.3 billion stars. And for those stars, 1.3 billion stars. For those stars, we have actually measured the parallax. So we know the distance to these stars. So we have for a fraction of the stars, we didn't have enough measurements or they were too faint. Yet at this stage for the measurements to be good enough to make a parallax. Okay. For this more or less the same subset, we also have measured colors of the stars. So Gaia carries on board two prisms that split the light into tiny rainbows effectively. And then we can measure the spectrum at low resolution. But for this data release, we just summed up the light and the two that we get through the two prisms. So one in a blue, there's a blue band covering the blue half of the optical wavelength range and the red band covering the other half. And this tells us enough to say something about the temperature of the star, luminosity, et cetera. And is it enough to like fully classify them into the... Not enough to classify them in detail. But what we can say is, and this is this circle over here. So we have 460 million stars. We have a good estimate. We have a good estimate of the effective temperature. So the, well, roughly speaking, the surface temperature of the star. And then for a similar number, about 80 million, we know something about how much dust there is between us and the star. So the dust makes the star looks redder than it should be. And we can estimate that from the colors and the parallax. And we also, you can also calculate the luminosity of the star and its radius. Also all from this information. Now you see a small circle over here. We get a... I can't even see it. The people at home can't see it. This is... And this... So we're going through like a whole list of what sort of stars you found, right? Or whatever... No, this is the data contents of the catalog. The data content, yeah. Just saying what's in the data. So this circle here represents the stars for which we have measured the radial velocity. So that means we can see that they're coming towards us or moving away from us. And this is done with a higher resolution spectrograph on board, where you can actually see the individual absorption lines of the stars. And by looking at how they shift, you can measure how fast the stars are moving. In the line of sight. Because the proper motion that we measure, that's this bigger circle, is only the motion across the sky. And we need to know the other component to get the 3D motion. Yeah, yeah. And this is for 7 million stars. So that's a very small fraction of the total catalog. And one reason... The main reason is that the spectrograph can only go to a much brighter limit than the rest of the mission. And for this particular release, we focused on the very brightest stars out to magnitude 12. But it's still 7 million radiovolts. So it's the most radial velocity ever collected by a single instrument. And this only represents less than the first two years of data. So that's already a very impressive feat. Yeah. And this is one of the data sets in combination, of course, with the parallax and the proper motion that is most used at the moment to analyze the Gaia data. Yeah. Now, here we see a very small circle that represents about 550,000 stars. What Gaia does is it measures the stars repeatedly over the course of five years. So each star on average gets measured about 75,000 times. And that means that we also... In those five years, 70 times. In those five years, yeah. And so that means that we also know whether the star is varying in brightness because we constantly can compare the brightness at one moment to another. And almost every star is actually varying in brightness, but most of them at a very low level. But there are also stars that are changing very significantly in brightness. One example is the star Mira, which really changes by factors over the course of a year and a half or so in brightness. And there are many stars that are changing very significantly in brightness. And there are many stars that are changing very significantly in brightness. And there are many more of those examples. And the nice thing about variable stars is that for some types, if you know how often they vary, you know their intrinsic luminosity. And that means you can estimate distances to them very easily. Oh, okay. And of course, these kinds of what we call standard candles have to be calibrated by parallax measurements. Because you need to know the distance to at least one of them to actually calibrate this relation between the period of variation and their luminosity. So we have light curves. So time series of brightness measurements for 550,000 stars. And in the future, this will be much more. We estimate that there must be tens of millions of stars in the catalog that are varying sufficiently for us to make a light curve. But that will come in later releases. And then the very smallest circle here, that represents not stars, but asteroids in the solar system. Oh. About 14,000 of them. Accidentally, you recorded a whole bunch of asteroids. Yeah. So Gaia looks at everything. While we're at it. While we're at it. Yeah, while we're at it. Everything that is in the solar system. Yeah. Is a point source in the sky. So that means also quasars, for example, or cores of very far away galaxies, but also asteroids in the solar system. And the good thing here is that the astrometry of the asteroids, so the position measurements at every point in time, are the most accurate ever done for asteroids. So we get extremely accurate orbits for these objects. And in fact, for these objects that have been measured for only two years, for some of them, the orbits are very, very accurate. For some of them, the orbit just on the base of those two years is of better quality than the measurements from the past 100 years combined. Perfect. So these are known asteroids. They've been measured before. And Gaia will certainly also discover new ones. And in the end, we will probably have a catalog of around 350,000 asteroids. And the beauty there is not only extremely accurate orbit determination, but we also get all the colors because we measure also the colors for the asteroids just like we do for the stars. And that means you can also classify asteroids into different types. Yeah. Depending on the composition, the way they reflect the solar light is a bit different. And does this have any… It's a side mission. It sounds like a side mission. Yeah. Does this have any relevance to possible collisions with Earth, for instance? Yes. So Gaia can see in directions at any one time where we cannot look from Earth. We can only look towards the night side, of course, to monitor for near-Earth objects. And Gaia can look at right angles away from that in both directions. Oh, yeah. And a bit closer to the sun. So it can catch… It can catch near-Earth objects at moments in their orbit where we wouldn't see them from the Earth, but you can see them from Gaia. So what we have in place also at the moment is a system that goes through the observations every day. And if we think we found a new asteroid and we every now and then find one, it may be that this particular asteroid has an orbit which is oriented such that Gaia will just never see it again due to the way we monitor the sky. And so it's very important to immediately follow up. And so what we do is we send out an alert to the community, hey, we think we found a new asteroid. And we can predict for every telescope on Earth exactly where the asteroid will be over the next days and weeks. And so that observers can go out and try to catch it. Oh, that's cool. And then you get a better orbit determination. Very cool. And just for my understanding about Gaia and what it does, what it can see, is it basically just the little circle around where we are that we can see? Or is there something else that we can see? Well, I think that the first thing that we can do is to look at the orbit. And then we can see the orbit. And then we can see the orbit. And then we can see the orbit. And then we can see the orbit. And then we can see the orbit. And then we can see the orbit. Or is that more? Yeah. There is more. Let me see if I can Is it just our little corner of the galaxy that you can see? Or is there more? Yeah. There is more. Let me see if I can find something. Okay. pull up an image we have to put a lot in the show notes today we do i'm not sure are you keeping track herbert not very much the gaia app i have the gaia app yeah yeah it's probably all in the gaia app and this chart that anthony has him well i suppose he's going to give us the url yeah yeah or send you the images or yeah because sometimes i've seen this this picture of the milky way how far our radio signals have traveled since the invention of of radio okay and it's like this super super tiny circle around where we are in the milky way very far we haven't come very far and i'm i'm just wondering if um if you if you look out at the milky way at night um you're you're you're look well here in the northern hemisphere we can't look into the milky way we're looking out of the milky way sort of right yeah um if if that is what you uh what you're measuring too all right so okay okay here's a nice picture i'm just describing it what i'm seeing i'm seeing the milky way from sort of a top view spiral arms yeah so it's fake because we've never seen the top view of the milky way of course for the time being no and then i see this one point that's very bright over here yeah and then it goes and then it sort of gradients out into less yeah so the so the background image is an artist impression of the milky way we think it might look like this but we're not sure i mean this is something we want to find out actually with gaia and what you see is the middle part is a milky way and then you see the top view of the milky way and then you see the top view of the milky way if you look at the background image that's what i called the bulge earlier which is also where the center of the milky way is with the supermassive black hole and the sun sits in the middle of this greenish purplish region about 30 000 light years away from the galactic center about halfway the rim of the galaxy yeah more or less we're sort of in a in a side arm we're not all the way in the end but we're sort of like halfway towards yeah we're in the suburbs not a very special place no not a very special place but suburban we knew that yeah sort of in between two spiral arms we think oh really oh so where it's more there's more countryside where we are so what you're seeing is the the false color part uh the what which goes from purple to green to yellow to red etc that is the density of the predicted density of the stars that we see with gaia most of them are concentrated around the sun and that's because stars are typically uh much fainter than the sun so if we want to see them they have to be close to us um so we are covering with guy about a quarter of the whole milky way disc at a quarter that's a relatively high density but in fact guy can see stars all over the milky way depending on the type of star you're looking at you can see it all the way to the other end of the galaxy and we even measure stars in the andromeda nebula which is a galaxy about two million light years away from from us accidentally or accidentally because that's funny we we simply simply say we we measure every point source that is bright enough so brighter than magnitude 20 and it will enter our detection system and get followed on board and we collect the measurements but that should be giants if you can see them at two what was it again two million light years away yeah so these will indeed be typically the the very bright massive stars that we see and sometimes of course you might have a star cluster which to us looks like a point uh but in fact is a is a sigma anymore so androids aren't so incredibly Agnes away from these very in strong areas and as an Sé個人 we don't know exactly Why is it that far away from the milky way but it her just by looking at the milky way stars will be further away from us and in a way I if I close our eyes well look at us all take a look the dry cannot focus too much on form giving light зап way to make them just try to do that this is way chin in minus 맞아 again yelled you knew that that would take into account even know what the the element Well there's one more тем that the by Meg 1999 used to be不了 I have made maybe 200 for that since it kind of happening that's the reason how by I mean if we take a look at that because a star is coming to us how many millions are light years away from uLtranises how many threw away So just to compare where we were with Hipparchus, Hipparchus surveyed basically only the central purple area about a couple of hundred light years around the sun, which was accurately mapped by Hipparchus. And Gaia is extending this essentially all over the Milky Way. So it's really an enormous step forward in our knowledge of the Milky Way. Now, Gaia was launched in 2013, right? Yes. Yeah. And you told us there's this five-year period in which data will be collected. Haven't these five years passed now? Just about. The launch was in December 2013, and we spent half a year commissioning the spacecraft, so checking out the systems. So we've been observing since July 2014. So this July 2019 will be the end of the nominal mission lifetime of Gaia. Right. But ESA has extended it. It's to the end of 2020. And also there's a preliminary permission to go on until 2022. And we know that we can go on at least until the middle of 2024. You mean fuel-wise? Yes. So we have two systems on board for propulsion. One is the normal propulsion to maintain the orbit of the satellite or do rough maneuvers. That's fuel enough for decades. But we also have a system of microtrusters on board, and they're capable of delivering micronewton thrusts. So very, very tiny. And they are used to very accurately control the spin rate of the spacecraft. Right. And these are ion motors? No, this is cold gas. Cold gas. Yeah. And this cold gas, of course, is limited. I think we took on board well over 50 kilos. So that's just like releasing a puff of air and getting some thrust from that. Yes, exactly. Okay. And we use about 12 grams a day of this cold gas. And that's a fairly accurate measurement. We can estimate that in various ways. And then if you know how much was in the tank to begin with, you can extrapolate how long. 12 grams a day? Roughly. Okay. Over years and years. How many kilos of this stuff are there on board? I think we started with between 50 and 60 kilos. All right. How big is GAIA anyway? So let's look at an image of GAIA. It's the easiest. Usually they're like a car. I'm guessing two meters tall. Two meters tall? It's three meters tall. Okay. That's good enough. Three meters tall. Yeah. If I'm getting within a factor of 10, I'm proud of myself. Exactly. Oh, yeah. And you should be. You should be. And you said, so ESA has extended the mission, right? Just now. What does that give you? What does it give you extra? What can you do in the next few years? More precision. Yeah. Let's get back to that question just now. Here's the image of GAIA itself. Oh, look at it. It looks like a pancake with a cylinder in the middle. Yeah. Yeah. What does this look like? That's a molasses. No. Molasses. So the diameter of the sun shield, the big disc, is 10 meters. It blocks the sun. It's a sun shield. Yes. So the sun is behind. The pancake blocks the shield. The solar panels on the other side. The solar panels are on the other side. Right. And the sun shield is on the other side. Right. And the sun shield protects the openings of the two telescopes. It looks like a mushroom upside down, like an upside down mushroom. And so the top of the mushroom has solar panels and blocks the sun at the same time. Okay. We don't need that in the show notes. No, no. I'm just describing it. Yeah, yeah. And so we're now talking about the stem of the mushroom, of the upside down mushroom that has all the instruments. Yes. So in the stem, there are two openings to let the light in. And we have two telescopes on board. And we're looking at two lines of sight on the sky at the same time, separated by about 106 degrees. And that's the fundamental trick we use to make sure that the parallax measurements we make are on an absolute scale so that we don't have to calibrate it in principle against anything else. Yeah. And so the spacecraft itself is three meters tall, weighs about two tons. It's a large, it's a hefty spacecraft. Yeah. And if you could stand over there, you would just, yeah, you would just not be able to reach the top. You can't, you wouldn't be able to climb on top of it. You would? Yeah. Three meters? You can climb on top of three meters? No, no, no, no, no. No. No. I was thinking. If I would help you up, you would be able to climb on it. My first guess of two meters, I could do that, but not three meters. Not three meters. No. You're right. You're right. Yeah. If you're ever in the position to be at the European Space Astronomy Center near Madrid, which is where all the space astronomy missions are run from, there's a one-to-one model of Gaia sitting there. Cool. It's outside. It was actually built in Lisse, this model. Oh, here in Holland. Yeah. Wow. Beautiful in spring with the tulips. Yeah. That's where all the tourists go when it's spring, right? Lisse. Sure. But they also build spacecraft models. Apparently. They grow tulips and build spacecraft. Crazy. I didn't know that. Spacecraft models. I didn't know that either. Hey, but launch in 2013, some preliminary work before it really got to work, the satellite, there was a first data set. I don't remember when. There was a second middle of last year, I think. Yeah. So the first release was in September 2016. Right. And then last year on April 25 was the second release. And the next will be in the middle of this year, July. No. No? In 2021. 2021? Yeah. Yeah. Okay. And then you have to get to work with all that data. Then the Astronomical Community gets to work with all the published data and do the science. Yeah. And the only thing we deliver is we turn the raw telemetry of the spacecraft into data that the astronomers can actually interpret. So the catalog, in effect, and that gets published immediately without us doing anything with it. So it's really open science, literally. So the only thing we do is we process the raw data and then we immediately provide it to the community so they can do science with it. Yeah. And every next data set just gives you more precision. Is that right? Yeah. It gives you more precision, but also more types of data. So what I mentioned before about the colors of the stars is that right now we have only a rough measurement. We can tell you it's blue or it's red or something in between, but we are actually measuring much more detail than that. So we have these two prism spectra, which have too low resolution to do detailed spectroscopic work, but they have enough resolution that you can say much more about the stars than what we are doing now. Yeah. And that's one of the things we're adding in the next releases, that we analyze those spectra to make better classifications of the stars, to better characterize them. The other addition next time is if we follow a star on the sky and we see its spiral motion, sometimes you see that it doesn't exactly follow the spiral motion. It makes little deviations. And this is a sign that there is something in orbit around the star. Like a planet. Oh, yeah. A planet. It could be another star. We talked about that last week. Exoplanets. Exoplanets. Was it last week? That was two weeks ago. Two weeks ago. Yeah. With Inge Loos Tenkater. Yeah. So look up that edition of Space Cowboys. Yeah. But this Gaia satellite does work that's relevant to exoplanets as well. Yes. So both from the astrometric measurements, so the position measurements of stars in the sky, what I just described, and from the radial velocity measurements that we do, we can find double stars. And if the thing that is in orbit around the star is small enough, it will be a planet. The planets will mostly come from the astrometric measurements because they're the only ones precise enough. And we think that we'll, based on the five years data, we will find maybe 20,000 stars with planets around them, down to Jupiter mass. So we can only find big planets, not the very small ones. Otherwise it doesn't wobble enough. Yeah. Yeah. Yeah. So the idea is that in 10 years is that we will probably increase then the number of planets to 70,000. That's the current estimate that we have. And to come back to the reasons for this extension, of course, if you double the lifetime, you collect twice as many photons. So that means that everything is 40% more precise. Now that by itself would not be enough motivation to double the lifetime. But if you double the lifetime, you also measure the motions of stars much more accurately because the longer you measure, the better you have a handle on the actual velocity of the star across the sky. So there you gain a factor of almost three in the proper motions of the stars. So that's very interesting because it's often stars that are very far away in, for example, dwarf galaxies or streams of stars that are remnants of dwarf galaxies that we are interested in. And then the proper motion precision is crucial. And if you're interested in things like double stars or planets, then you can gain factors of up to 20. And is the idea to follow up on all the data that you have now, is the idea to then look at more, let's say, broad implications of these things? Or will we maybe, so this is how the Milky Way moves, or this is what dark matter does, or is it more trying to find peculiar things so that we can zoom in at one star to figure out maybe, like what we use this data for, from like the bigger questions, or can we use them? Or can we use them individually almost as well? It is used for both. So Gaia, in fact, has impact on every area of astronomy. That's the beauty of the mission. When I go around now to present Gaia to colleagues and give them an overview of all the science that is being done with the mission, I constantly jump from one topic to another, from one slide to the next, because there's so many things you can do with Gaia. So yes, we can look at the bigger picture, the goal being understanding the Milky Way, one aspect of the Milky Way. One aspect of that is the distribution of dark matter, which we can figure out by looking at the motions of the stars. But there are also people who are interested in very specific topics. So there was a very nice paper in Nature a couple of weeks ago by a group from the University of Warwick in England. They used Gaia data to show that for the first time now we can actually see that in what we call white dwarfs, these are remnants of stars like the sun, and they're very small. They're about the size of the Earth. But they're as massive as the sun. So they're extremely dense stars. And they don't produce any energy anymore in the sense that they don't burn hydrogen or helium or et cetera in their interior. So the only thing they do is they cool down over the course of time. On their way to becoming neutron stars. No, they won't become neutron stars. They will just cool down. Never mind. Silly you. And sit there. And so, but the white dwarf is just for my understanding now that we're at it. So it has burned up all its hydrogen. Yeah. That has... Yeah. That has become... It's basically a very dense star consisting only of carbon and oxygen. Carbon and oxygen. Okay. That's all it's... And it's not burning that anymore, but it is still... There's still a lot of heat in there. And so it's slowly cooling down. So it's light and it's a light that slowly dies out. And slowly dies out. But in the process of that cooling down, the interior will at some point actually crystallize. Oh yeah. And this means that... You will get a diamond. Temporarily the cooling down stops. And this creates a particular feature in the observations that Gaia does. And this was exploited by them to show that now for the first time, this was predicted 50 years ago that white dwarfs would crystallize. And this is the first time you can really clearly see it in the distribution of luminosity versus color of these stars. Is this the diamond stars that... Yes. I suppose you could call it a diamond. You could call it a diamond. Can I please call it a diamond star? Go ahead. There are diamonds, huge diamonds the size of small stars. People talk about super blood wolf moon. I get to talk about my diamonds in space. You get your diamond star. No, but I love the idea that there's massive, massive, massive diamonds just floating out through space. I have this question. When you collect data on the location and the movement of stars, I think in principle you might be able to wind back the tape and find out which stars have collided in the past with other stars. Is it an application of this data set? Yes. So we can do it both in the past and in the future. So one popular application is to look for stars that are going to pass very close to the sun. Yeah. And we know of one particular star. It's called GJ 710. It's not a particularly romantic name. And that star will come to within about 20,000 astronomical units from the sun about one and a half million years from now is the prediction. And that's how many Pluto orbits, for instance? Well, Pluto is at 40 astronomical units. But a better comparison is the Oort cloud of comets, which sits at 50,000 astronomical units. So it will actually go through the Oort cloud. And this is a star we're talking about? Yes, a star. How bright will that be on a night sky? It will just about be the brightest star. Not quite. What? But it's a star almost like coming to visit us. Yes, but it's a very small star. I want a double. I want no night. I just want to be able to read books at night. Yeah. But the star is so much less massive than the sun that also it's very dim compared to the sun. So it will brighten, of course, as it approaches us. It will be almost, I think, the brightest star in the sky, but I think not quite. I tried to calculate it. That's interesting. But it tells you how huge the distances still are. Yeah, of course. But it also it's such a great example of like almost a minuscule detail that you can find out about these stars. Like this. So this is the Gaia mission is trying to give you these answers to these really large questions about how the Milky Way works, but also gives you like these crazy little stories about like, oh, a star is coming to visit our solar system. And that's in how many years, by the way? About one and a half million years. Okay. So it'll take a while. It'll take a while. Yes. Here's another question. Where's my 3D model of the Milky Way? That's being worked on. This is something that is not actually not so strong. Oh, that's great. Yeah. So it's very straightforward to figure out from the Gaia data. Although we have parallax measurements, the fact that they have errors on them make the statistical interpretation of these measurements more difficult. So formally speaking, you can say that the distance to a star is simply one divided by the parallax. And that works fine if you have small errors. But if the errors become a bit larger, which they are for most of the stars, then you have to be careful of making this inversion. And the statistical interpretation of exactly how far away the star is becomes more complex. And so, for example, measuring where the spiral arms are in the Milky Way is in principle possible with Gaia, at least for the ones in the neighborhood of the sun. Turns out to be quite difficult still. You need to select primarily blue stars that are located in these spiral arms, but then you need to be able to correct for the effect of dust, which we can only roughly do with Gaia. And it's not very good yet. Because stars tend to be typically far away, and that makes inferring the accurate distances a bit harder. So getting a very crisp, clear picture of the spiral arms is still going to take some time. But somebody's working on that. But there is work being done on this. Yeah. Hey, and what's Gaia Sky then? I see Gaia Sky 1.0. Yeah. That software. That software can indeed be used to actually make 3D movies of the space around us, because we know where all the stars are. Awesome. There we go. Yeah. Gaia Sky. But this is of course not a scientific model, and it works well for things near to us, where the distances are very reliable. But this could be a huge tool in the popularization of science, of astronomy. We have used it in fact for... So it's a tool that was developed as part of the work of this data processing consortium. And you could even incorporate it into a computer game, for instance. Yes. I mean, I think this thing can export everything in VR format. Yeah. It has a 3D function as well, and a virtual reality function. Beautiful. Yeah. Wow. So you can stand inside the Milky Way and... Cosmic Grand Theft Auto. Cosmic Grand Theft Auto. Exactly. Yeah. So this... And the software is open source and free. People can download it and play with it themselves. That will be my next question. The data also are public domain? Yes. The data are publicly available. And as I said before, without any proprietary rights for the consortium, so we don't get to use the data first. And then the rest, it's all immediately public. Great. And also for the general public, you can go to the Gaia archive. All you have to do is to ask for an account, which you get just like that. And you know, having a 3D model, actually I was just thinking about kicks, moving around between the stars. Yeah. But you can be an amateur astronomer using these data just as well as you can be an amateur astronomer having a telescope in your backyard. That's right. Yeah. And you can do your own analysis. So actually one of the people doing a lot of effort on trying to map the Milky Way out to large distances is an amateur astronomer. He's a mathematician of origin. And he runs the site galaxymap.org. And that's where you can find lots of material on the mapping of the Milky Way. Galaxymap.org. Yeah. I'm trying to find the name of one of the... I have an app or something. I don't know. I don't know. I don't know. I think I know the app. I don't know. I don't know. I think it's like an app. I don't know. I don't know the name of the app. I don't know what it is. But you can get this app. It's a computer. It's a laptop. It's a software at home, on my computer at home. It's not on my laptop. Where you can play around with just anywhere in the solar system. You can create solar systems. You can destroy them and et cetera. But I believe that when it comes to the Milky Way, they never have an accurate depiction of it because they don't know. So it's very cool. Like maybe you can send your data over to them that they... I'll look up the name as well. Sure. Of this, that maybe you can... that they that they i'll look up the name as well sure uh of this that that maybe you can yeah like you said gamify this whole thing that'd be great that's right yeah yeah um how much data are we talking about actually because you're sending this is all open but is this is this like a terabyte so what are we talking about yeah if you were to download the full uh gaia dr2 sort of second date release catalog it would be about 550 gigabytes compressed okay so once uncompressed it's about a terabyte so not prohibit it's on an external hard drive no not bad yeah but if you would if as a database expecting more the problem is of course to efficiently access the data um it's not so much in terms of volume but then when you say okay i want to have that specific star or that group of stars then it needs to be in a database and that's where a lot of effort has to go into to make it efficient and usable and then maybe a bit of a technical question but um in what kind of format are these data can a regular person use it at all so the files that you can download are available in comma separated format so the what you would use for excel but i wouldn't attempt to load it into excel but what you typically do is you go to the gaia archive and that there's a database in which all the data sits and you can basically make a sql query and then say i want stars of a specific kind or between certain limits in the database and then you can make a sql query and then say i want distance or certain limit in brightness you can make all kinds of selections the data will be stored on your local storage space at the at the archive and then you can download that data and that can be done in various formats and because that's often a much much smaller subset then you could in principle load it into excel if you wanted to work with that as an analysis tool typically what astronomers would use is a so-called virtual up virtual observatory table format which allows us to interchange also with all kinds of data and then you can make all kinds of other surveys spread around the web and fits is another popular very astronomy specific format it's very efficient etc but there's various formats that you can use to download data i found the game uh it's it's a universe sandbox two and you have space engine i have them both and they're both sort of the same idea both are universe sandbox universe sandbox and space engine space engine yeah yeah they're super cool to work with okay um when you're talking about that data set you already said that you're going to use the universe sandbox and you're going to use the space engine you're going to use the space engine so you're going to use the space engine but you're not going to use the space engine but you're going to use the space engine you're going to use the space engine elements of these stars that you save but just to bring it back for my own understanding if you if we have one star what do you know and how much how the translate translate the bytes just simple is this like a almost like a word document per per um like a one-page document per star that we know of it or how many data points do you have for this one well in the in the current in the current catalog we have the position of the star so that's two uh it's the two coordinates where it is in the sky we have the brightness of the star we have the parallax we have the two components of proper motion so how it's moving across the sky we measure that in two directions we have the radial velocity so how fast it's moving in the line of sight those are the very basic that's just a couple of numbers just a couple of numbers but for each of those numbers we have also errors on those numbers because it's a scientific database okay now you're talking we have the colors of the star that's three numbers so we have the brightness in three different bands again with with errors on them we have estimates for the effective temperature for the for the amount of extinction in the line of sight for the way the star's color was changed by the dust between us and the star and also radius luminosity and all these numbers come with error estimates on top of them so i think in the end you're talking about over 100 columns in the in the data проблема and all the information that's being taken out is the information that is being taken out by the data understandable outside theité of that data and that data of the multidimensional mine is the error estimate which is not found in the data so it's very difficult the database per star so it is it is sizable and this is only a subset of all the data will eventually publish and will then supercomputers just will they start making uh more of crunching crunching the numbers mathematical models of the milky way is that how this this will continue where will this go um so so the analyses can be can be very varied so it might be that you're interested in just one star so for example lots of people working on exoplanets are making use of gaia data because it's important to know the distance to the star because then you have a better estimate of the size of the star and that gives you a better estimate of the size of the planet if you're looking at planets that go in front of the star and dim the light a bit so the transiting planets you need to know really need to know the the distance so that's very simple you just look it up and you use it in your research on the other end of the scale of course are people who say well i i actually want to analyze the collective of stars so let's say all the stars for which we have the full motion so these are the seven million stars that have a radial velocity measured and these can in principle be modeled all together where you indeed build a model of the milky way and with that model you can predict the statistics of the motions of the stars you cannot predict each and every individual star how it moves but you can say that on average stars move with about 200 kilometers per second around the milky way you can predict the motion of the stars and you can say that on average stars move with about 200 kilometers per second around the milky way and then the spread in the velocities has a certain value and you can also predict the spread in different directions with respect to the milky way itself and all of that of course has to fit with the with the data so if it doesn't fit with the data you might want to change something in your model and if your model is good enough you just fix the parameters according to the data you're done and sometimes you learn that the whole model is just not it's just not working and you need to go to something more complex etc and that requires a lot of computational power depending on how you analyze the data i have a question about precision i read somewhere the precision precision of the gaia measurements is like distinguishing a euro coin on the moon from the surface of the earth yes and someplace else i read using gaia you could even watch a hair grow on the moon that's slightly more precise even even than a euro coin is correct i think the watching the hair grow is from uh i cannot do it off the top of my head but that must be from a much closer distance okay but the euro coin on the moon is correct so so the way we measure the precision of gai is by talking about the angles that it can measure on the sky so yeah because the only thing you do is look at the direction to a star and directions are always specified in angles so how far is it above the horizon how far is it east or west and we do it in a slightly different way but you measure those angles and gaia can measure in a different way so you can measure in a slightly different way but you lashe those angles and gai can measure angles, the most precise angles it can measure is 10 micro arc seconds. Now, an arc second is, if you divide a degree by 60, you have 60 arc minutes, and each arc minute is divided in 60 into 60 arc seconds. And one degree is about the diameter of the moon as we observe it, right? The moon is half a degree. Half a degree? Half a degree, yeah. So the moon is about 1,800 arc seconds, and Gaia measures 10 micro arc seconds. Whoop-dee-doo. And so that's... And micro is a millionth of an arc second. A millionth of an arc second. And so that indeed translates, if you take a euro coin, which is about two centimeters in diameter... It's like an American quarter, a little smaller. Put it on the moon, and you could actually see it from Earth lying on the moon, then you would have eyes that would be capable of measuring angles of 10 micro arc seconds. So you told us Gaia has also charted some asteroids. Mm-hmm. You ought to be able to distinguish lots of details on the surface of those asteroids, but Gaia doesn't do that, does it? No. No, no. So the telescopes of Gaia are about one and a half meter diameter. Mm-hmm. So they are smaller, actually, than the mirror that the Hubble Space Telescope carries. And we cannot see surface details, because the only thing we see is a point source. Okay. Okay. Okay. Okay. Okay. So Gaia just says, I see a light source there, and I'm going to watch it for a while and see how it behaves. Yes. That's all it does. And I know we're nearing the end of our show, but I still got an important question. I think yesterday we were on the phone quickly to say hello for the show, and I think you told me something about the fact that you can... Like, what the results already have, like, what new insights do we have through Gaia? I think you said something that you can see that we swallowed up certain parts. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Yes. Of the galaxy. Yeah. Of the galaxy. Where you can see that we may be... That over there, there's like a blob that supposedly is not supposed to be there because it was added somewhat later to the Milky Way. Let's go... Let me see. I think I can find that. I compared it a bit to try to understand, and Anthony, correct me if I'm wrong, that almost as if you have a whirlpool of water, and it's just... and somebody drops in some paint. And you can sort of see that there's like a separate entity. Yeah, and the paint becomes a spiral itself. And it becomes a spiral itself, or at least a blob or something that's inside there. Is that comparison slightly, is that a good metaphor? Let me try to show what I explained. I don't have internet here, so I can't look up that particular animation. Oh, yeah. It becomes another graph. We can work on the show notes in the meantime. Universe Sandbox. Upside down mushroom, a picture of Gaia. Yeah, I got the Gaia app. Gaia Sky 2.0, GalaxyMap.org. Okay. Okay, so here's what I was talking about yesterday. If you look very far out in the halo of the Milky Way, with the aid of Gaia data, you can isolate the so-called streams of stars. So you see a very long, thin distribution of stars here. Thousands of stars. And these stars are essentially all moving on the... On the same orbit. So they're all moving in the same direction. And what this is, this used to be a small galaxy. And it fell into the Milky Way and it went in orbit around the center of the Milky Way, but far out. And because of the gravitational forces of the Milky Way, this galaxy was ripped apart. Right, yeah. And then it becomes a sort of a spaghetti spread out along its own orbit. That's the drop of ink in the kitchen sink. Roughly. Yeah. And that's what you see here. But if you look at it in detail, you see that there are sometimes gaps or certain features in there that are not exactly corresponding to a nice stream of stars. And we think that these gaps can be, or we know that these gaps can in principle be caused if a massive object passes close to that stream. It disturbs the orbits of some of the stars and that appears as a gap on the sky. Now for this particular stream, which is called GD1, after the people who found it first, they've determined that what disturbed this particular stream happened about 300 to 400 million years ago. And it was an object of about 5 million times the mass of the sun. Now, then they started looking for, okay, what could that be? Is it maybe a globular cluster that we already know, which passed by, but they looked at all the orbits of globular clusters. 500 million, so a black hole? 5 million. 5 million, okay. No, sorry, 500 million. 500 million, yeah. Years ago. So it cannot be a globular cluster, at least not one of the known ones. It's not one of the known dwarf galaxies around the Milky Way. So they speculate that this could be the first time that we see a massive object, which consists completely of dark matter. So it has no stars inside it. And it's been predicted for a long time that our halo should have, so the halo consists largely of dark matter. There are stars, of course, but the most of it, the mass is in dark matter, but it's not smoothly distributed. The prediction is that it has substructures. There's lots of small dark matter, blobs actually running around. And these are just concentrations of dark matter particles. And it's possible that this is the first evidence we have of such a thing. This still needs to be confirmed. It might be that we manage still to find some other object with stars in it that caused this disturbance. But it's a very tantalizing result. Still nice to have this little preview of research results. Yeah, of what's coming, right? Because it will take years and years and years, maybe even decades to plow through all this. And draw conclusions. Decades for sure. Yeah, decades for sure. It's fascinating mission, Anthony. It's amazing. It's so cool that we sort of started to map the Milky Way. What will be the next? What will be the one that ups it again with a factor thousand? That's hard. That's really hard. We have been thinking about this, but if you really want to go, let's say a nano arc second precision, so another factor of micro, but nano, or even if you want to go 10 nano arc second, you can do that. Yeah. 10 nano arc seconds precise. If you want to use the same principle, you would have to scale up the satellite to having a configuration of different satellites because it has to be. Ah, yes. The size of the mirror effectively has to be much larger. Artificially big satellite. And you can do that with interferometry. So that's extremely expensive and very hard to do right. So it's not clear this can be done. Sounds like a good challenge. And another aspect is that if you, for the measurements that we do with Gaia, we have to worry about the fact that the sun, bends the light of stars that comes from outer space. Ah, you have to take that into account. And we have to take it into account all over the sky, not only for stars near the limb of the sun. And in fact, we have to take into account the light bending by Jupiter, Saturn, all the major planets. That's incredible. Sometimes even if an asteroid is close enough to a star and it's massive, you have to correct for this. That's crazy. Now, if you go down to nano arc seconds, this becomes a much larger problem because then you really have to worry about knowing exactly where all the bodies in the solar system are to make, make these corrections to sufficient accuracy that you're not constantly, the position measurements of stars, not constantly being blurred as it were by light bending effects. So there are also some fundamental, and it's a couple of other fundamental problems that we would have to tackle before you could get to those accuracies. Yeah. Well, let's first start crunching that Gaia data then. That's right. Yes. Thank you so much, Anthony, for being here. It's been great. Really wonderful. Really great to finally, to do, I mean, it's a privilege to do a full show on this because Gaia, Absolutely. it's one of the greatest missions there is, I think. So thank you very much, Anthony. And we wish you lots of success. Yes. Thank you. Working on this. And thank you to our listeners as well. You can go to patreon.com slash space cowboys to support the show. Herbert Blankesteijn, thank you so much. Thijs Roes. Yes. Thank you too. And thanks to everybody who's helping out and all the listeners. Soon we're going to be, so you can follow us on YouTube and Spotify and Twitter. Space at space cowboys pod on Twitter. Exactly. And we're working on getting a live stream fixed. Who knows? Maybe in the future, in the next few episodes, we'll announce a live stream on YouTube coming up. Working on it. Working on it. Thank you, Thijs. Thank you, Herbert. Everybody see you next space cowboys podcast. Bye bye. Bye.