A Watery History of Mars

We have to go to these places where we know that there is liquid water on Mars today and that is exclusively underground. Does Mars have a history of glaciation? And why the heck did they think there were canals on Mars? Hello, welcome to the Supermassive Podcast from the Royal Astronomical Society with me, science journalist Izzy Clark and astrophysicist Dr Becky Smidurst. We thought it was about time that we did a deep dive into water on Mars. So grab your space swimsuit everybody. Yeah, so when did Mars have water? What was a wet Mars like and where did all the water go? We'll be speaking with Jo McNeil from the Natural History Museum and taking a look into the Royal Astronomical Society's archives. And obviously Dr Robert Massey, the Deputy Director of the Royal Astronomical Society is here. So Robert, when did Mars have water? Well, a long, long time ago in the sense of lots of liquid water on the surface, we think. So the idea is maybe 3.8 billion years ago, which if you think the solar system is four and a half billion years old, that's a really long time ago. Mars had a much thicker atmosphere, probably a carbon dioxide one. And that higher surface pressure means that water could be present as liquid because if you have say water in a vacuum or a very low pressure, it can only either be ice or gas. To have a liquid, you have to have a certain pressure. And that was present apparently in early in Martian history and it's what makes it possible on Earth today as well. You know, if you went very high up in the atmosphere, the Earth, you can't have liquid water there either. And we see evidence of its action on the surface, you know, evidence of giant flood shorelines, materials cemented together, and in some minerals that can only be made with the help of liquid water that the rovers have found, the various rovers going around the surface. And actually, of course, the only caveat on this is that it still has water today and on the surface in the form of ice. And we sometimes see the evidence of these little transient flows, you know, maybe something's bubbling up from underneath, but it doesn't last very long, just because the soil is super dry, the atmosphere is too thin for it to stick around. So it just disappears again. But there's a lot of interest in how much that was there in the past. So this is hopefully a great episode to talk about that. Yeah, absolutely. So there was a recent study on the subject and it comes from the Open University. And Joe McNeil from the Natural History Museum was part of that study. He specialises in Martian geology. And he started by telling me what Mars was like when it had water. Mars had water about three and a half to four billion years ago. And it would have been very, very different to the dry, cold, red desert planet that we see today. So it had a much thicker atmosphere and a climate that could support this liquid water. And this means Mars would have had an active hydrological cycle with rain river systems, huge lakes, and maybe even an ocean in the northern hemisphere. That's so different to how we like picture Mars now. So how do we actually know this? Well, I think Mars is really fascinating because we can look at its surface using orbital spacecraft and explore it on the ground with rovers. And its geology and its mineralogy point to large amounts of liquid water, shaping the landscape billions of years ago. So many of its surface features resemble things that we have on Earth. So we have things like valley networks, which are branching, dendritic sort of drainage patterns. And these resemble terrestrial river systems formed by rainfall and surface, surface runoff. So liquid water flowing along the surface. We also have things like outflow channels, which are these enormous kilometers, tens of kilometers wide, deep channels, which are carved by catastrophic floods. This is probably from a sudden release of groundwater. So if we have lots of water locked away in the crust, and then something causes that to escape, it all floods out all at once. We have things like river deltas, which are these fan shaped sedimentary structures, which form when rivers deposit sediment into a standing body of water, like lakes or seas. So think about the Nile Delta or the Mississippi Delta, we have similar features on Mars. And there are also possible shorelines and tsunami deposits in the northern hemisphere, which may point to the presence of a huge ocean in the northern hemisphere, taking up about the top sort of third of the planet. But this is quite a contentious point. Not everyone agrees on this. And there are, it's a still an ongoing discussion. I'll say discussion and not argument. Okay. And I mean, I love the idea of that, though. I don't think I've ever thought about tsunamis on Mars until this very moment. So that is fascinating. And so do we know where this water would have come from? Any initial ideas on that? I appreciate that's probably quite a difficult thing to find out. I mean, it was probably delivered to Mars in the same way that it was delivered to Earth. We think it's probably from comets very, very early on. I see I see bodies delivering this water to the to the inner planets. We have, as well as this physical evidence, we have telltale signs in the mineralogy as well that we can see from orbit. So we can investigate what the composition of the surfaces and we see a lot of minerals like clays clay minerals, which form only through the interaction of rocks and liquid water over pretty long periods of time. And we also have things like sulfates, which are salt deposits, exactly like what we get in dried up lake beds on Earth. These are really useful environmental markers to sort of investigate the water on Mars. And so how similar would that environment have been to how we know Earth to be today? In many ways, Mars was probably the most Earth like planet in our solar system. It wasn't an exact twin. There are differences. For example, the water probably wasn't nice and warm and tropical. When I say water, it still would have been incredibly cold. So there would have been a lot of ice around, but it would still have been a dynamic planet with an active hydrological cycle, weather, erosion, and possibly even some areas with habitable conditions. Do we know how much water would have been on Mars? You know, I think when we think about Earth, we we do think of it as a water planet. There's a lot of it here. And would that have been similar for Mars? And I guess, would the moon still have had that interaction that we see with our waves and things like that? I think the parallels are so interesting. Yeah, if there was an ocean on early Mars, there probably wouldn't have been sort of tides. Mars's moons, Phobos and Deimos are simply not large enough to cause this tidal effect that we have on Earth, obviously, our moon relative to the size of the planet is absolutely enormous. Mars wouldn't have had tides. In terms of how much water Mars had, yep, people have calculated that. In fact, there is still enough ice on Mars that we can calculate how much there would be if you melted it all right now. If you melted everything in the polar caps, and I don't know if this takes into account the permafrost in the soil, but you'll end up with about 35 meters global equivalent layer. So it's quite a substantial amount is still left. But we know a lot of it has been lost. So it was probably almost certainly more than that in the past. Okay, and let's talk about losing that because what happened to all of that water? We don't see these huge potential oceans or these rivers on Mars anymore today. So what happened to that water? And why did it disappear? Great question. Mars is quite a lot smaller than the Earth. So its radius is a little bit over 3000 kilometers. Compare that with about just over 6000 kilometers with the Earth. Because of the way that spheres work, you end up with about an eighth of the volume of Mars compared with with that of Earth. And that means it just cooled down really quickly. And as its interior cooled, the convection currents in the core stopped and these convection currents produce a global magnetic field. We still have this on Earth, thankfully. And this protected the atmosphere from the solar wind. But obviously, as Mars cooled, these convection currents stopped. This magnetic field slowly went away. And without that shield, the atmosphere was gradually sort of stripped away into space. And as a result, the pressure dropped, the temperature dropped, and liquid water couldn't remain stable. So it either froze into the ground, or quite a lot of it likely escaped into space. So Mars didn't lose all of its water. It still has quite a lot of it locked away as ice. It just became locked away as that ice as the planet underwent a gradual but irreversible change in its climate. Yes. So let's talk about that a bit more. Where do we still see, I guess it's now solid water on Mars today. And then I want to also talk about liquid water afterwards, you know, is there any, do we see any signs of it? Yeah, so there are two main places that we can find water on Mars today in its ice form. And that is at the poles. So Mars has two wonderful polar caps. They are mostly made of water ice, but there's also layered carbon dioxide dry ice within that water ice and mostly on top of it. That freezes away and resublimates seasonally. Beneath this carbon dioxide cap, as I said, there is a sort of permanent core of water ice, it's kilometers thick, so there's an awful lot of it. But that's in the North Pole, South Pole has slightly less, but that's where you find a lot of it. Underground is the other one. So away from the poles, we've used radar to identify subsurface ice deposits, which is effectively where the ice is retreated into the crust and frozen in place. So this exists as permafrost, never melting ice. And it's mostly in the mid-latitudes. So it exists as sort of this frozen ground, which is a mix of dust and rock and ice. Yeah, so those are the two main places we see it on Mars at the poles and locked away into the crust. Okay, so you've talked about how we look for that. And I guess I want to understand what does this mean for that all important question on life on Mars? You know, how key is water for that? And can it tell us anything about that possibility of life on Mars? When we think about life on Mars, we can really define it into past life on Mars and present life on Mars. With past life on Mars, we tend to go to these places that have this geological evidence that there was lots of liquid water here in the past. The next rover that we're going to send to Mars is Rosalind Franklin, which is going to be doing something no rover has ever done before. It has a two meter long drill on its front. And it's going to be drilling down into the into the subsurface, which is probably where these signs of past or present life are more likely to be better preserved away from the Martian surface environment. We can also think about life on Mars today. And so we have to go to these places where we know that there is liquid water on Mars today. And that is exclusively underground. As these icy, briny lakes underneath the polar caps, we've used radar to interrogate the polar cap. And we found lakes of probably very, very salty hypersaline water. So we need to think about what kind of life might be able to exist there, be bacterial, what kind of places on earth might we see these high altitude lakes sort of sort of hypersaline places on earth, basically, we've done the present. So let's look to the future. Why is it so important for a Mars mission that there is accessible water on Mars? From a human exploration point of view, water's vital. It will be the main sort of defining aspect of where we send people when we eventually go to Mars. So obviously, people need water to drink, to grow food, we will need water. But there's also things like getting oxygen, we can split water into hydrogen and oxygen, we need oxygen to breathe. That also has the side effect of producing hydrogen. Hydrogen and oxygen can be used together for rocket fuel. We can't take all of our fuel with us. To Mars, it's far too heavy. So we're going to have to make it there. So really, when we send people to Mars, it won't be to the most geologically or scientifically interesting places first. It'll go to the safest place that has the correct resources. And these will be the places that we are targeting, where the subsurface ice is within a couple of meters of the surface. So it's got to be very, very shallow ice. Thank you to Joe McNeil from the Natural History Museum. Now, we've actually had some listener questions. I know we normally do that later, but I thought they would be better placed here. So Becky Nuba on Instagram asks, does Mars have a history of glaciation? Good question. It's not just a history. It's actually that Mars has current glaciers as well. So they're not planet wide today like they used to be when there was much more water on Mars in the past. They're only on the poles that we find them today, which we know have visible ice that you can see sort of in imagery as well. And if you look at some of the imagery that's been taken of the current Martian glaciers from satellites in orbit, they're just incredible. We see all the features that you recognize from glaciers on Earth, the flows of the ice and these deep grooves on the surface. And you see them even spreading out as they sort of exit valleys and out into planes as well. Now, it is worth stating that like on Earth, the glaciers on Mars are not made of pure ice, right? There's a lot of rock in them as well that's getting moved with the ice flows through all the sort of seasonal melting and freezing cycles that you had. And the latest study that I could find put them around about 80% ice, people reckon, 20% rock. So just to give people like an idea of what we're talking about here. And it is water ice as well. It's not carbon dioxide ice, for example, although it is thought that is possible to maybe get like a pure carbon dioxide ice glacier on Mars, but that would be very, very rare. In terms of the history, which was actually the question that you've asked, the glaciers were more widely spread. And that's thought to be because Mars' axial tilt was actually very different. It was much more extreme in the past. It was more like 45 degrees tilt rather than the 25 degrees that it is today, which is obviously very similar to Earth's 23 degree tilt of our axes that gives us our seasons. So when you have that high of a tilt, you get much more extreme seasons. That's when the ice will build up. And so a lot of the features that we see on the surface of Mars that appear to be glacial in origin, even on the equator, right, have been carved out by ice, right? In the same way that, you know, like Yosemite Valley, for example, in California is from Yosemite, that's thought to have been shaped by glaciers in the past ice age on Earth. There's no ice there now because of the seasonal differences. We're usually to get snow up high there, obviously, but not in the valley itself. Do you? I don't know. Maybe some Californians can tell me to get snow in the valley of Yosemite. I don't actually know. But you don't have a glacier there, essentially is what I'm trying to say. And just to continue, like comparisons to Earth for anyone who's curious, because I was, Mars' glaciers do not come anywhere close to the size of Earth's glaciers in terms of volume length or anything. They're much smaller in size, which I guess you'd expect because they're just not as much ice on Mars as there is on Earth. Okay, amazing. Thanks, Becky. And Robert, Eric Moore asks, could frozen water be used to replace the atmosphere on Mars, like in the movie, Total Recall? I'd like to say that producer Richard has also said, just to be clear, the 1990 version is so much better than the 2012 remake, so. I think I've seen either. So maybe that's my homework. Yeah, exactly. I have fortunately seen the 1990s version, actually, the 2012 one. Now I'm really struggling to remember which one. I believe it was the 1990s one. I think that's the one with Schwarzenegger, isn't it? Otherwise, my answer is going to seem nonsensical. So, yeah, Eric, the answer is this is in the context of several decades, probably since we discovered that Mars was not really habitable, that it was this dry, dusty world with a very thin CO2 atmosphere, cold and so on. There's been speculation about terraforming it, which means making it habitable like the Earth. So in theory, we could accomplish that by filling the atmosphere with CO2, some means of releasing that, large amounts of a carbon dioxide going in, maybe have some factory producing the things we don't want to flood our own atmosphere, methane and chlorofluorocarbons and all this stuff. Not great things, really, for the Earth. But I think, as for the question of water, I think any terraformers, if they've got that frozen water, a lot of it is weighed under the surface. They're going to want that for oceans and rivers and all the rest of it, rather than using that as the main atmospheric gas, if that were even possible. And as for the total recall thing, well, if I recall correctly, depending on which film it is, Arnold Schwarzenegger, so, Arnold sits there at the end of the film, is thrown out to some cavern with some ancient Martian tech, lying on the surface, suffocating, I know I'm sorry. I'll just plug my ear now, warn people, Robert. Anyway, and then the atmosphere fills with oxygen and water in a matter of minutes, enough that it doesn't suffocate. I think I can safely say that's impossible, that it would take many, many thousands of years to make Mars look anything like the Earth, if it's even possible. And there are some big ethical questions about it as well, you know, should you really change a planet to be like the Earth, which, you know, on the face of it, oh yeah, great, another Earth, but then, you know, I don't know, I worry about, well, are we just doing this to Mars because we're going to mess up the Earth even more, we're not going to try and maybe fixing the Earth would be a good idea as well. And if you're an astrobiologist and you're worried about the presence of Martian life and whether there is any, you probably don't want to radically change the environment and kill that all off before it's discovered. So those are the sort of bigger things, I think we've got to answer those questions before we even try. And it's probably very, very hard and very slow, even if we get to that point. Right, and there was like, you know, just because they could doesn't mean that they should, like, you know, never stop to think, I personally would vote no, let's not try and change the atmosphere of an entire planet. And Becky, Joe mentioned tsunamis on Mars and their deposits, like how would that work? And do you know how we would see those? Yeah, I mean, it's really interesting because on Earth, you know, tsunamis typically have, when you have an earthquake, right? So you have that shifting of the plate tectonics, like two plates shift, and that's what sends that sort of wave out that you have the tsunami coming from. But Mars doesn't have plate tectonics, like it doesn't have the sort of big continents that move and slip and, you know, like going under and over and into each other. So, you know, you have to kind of think, okay, well, where did tsunami deposits come from then if they don't take tectonics, but if you tsunami. And so probably people think that it actually comes from if you have a really large meteorite impact event, you know, into an old northern ocean that was on Mars that could have caused a huge wave of water and rocks to engulf the shoreline and could be one explanation for some of the features that we see in these possible sort of shorelines on Mars. Thanks, Becky. We will tackle some more listener questions later. As technology develops, we've been able to better understand Mars' landscape and how it's changed. But how did the Red Planet look to astronomers from over 100 years ago? And why the heck did they think there were canals on Mars? Izzy went to the Royal Astronomical Society to find out. I am in one of my favourite rooms in London. It's the library of the Royal Astronomical Society. And yes, we're surrounded by books right now. But we've got the addition of the Bicentenary Quilt. And it's like this 100 piece patchwork of lots of different astronomical features and stars all made in fabric. It's really beautiful and it's quite distracting. But I'm here with Sean, the archivist and librarian of the Royal Astronomical Society, to talk about what we have in the archives about water on Mars. And Sean, as always, you've brought quite the collection with you. I have brought a few examples from our shelves. These books contain some of the earliest detailed maps of Mars that were attempted by astronomers in the late 19th century. Let's have a look at the first book. It's called Other Worlds Than Ours. And it's written by Richard Proctor, who was a self-taught astronomer and a member of the Royal Astronomical Society, who was both a really good popular science writer and an astronomer who was taken very seriously by his peers. He did really original work theories and he was really good at mapping as well. The first page that we're looking at here, it does say Other Worlds Than Ours, it's that lovely sort of typeface. The full title is Other Worlds Than Ours, The Plurality of Worlds, Studied Under the Light of Recent Scientific Researches. So basically, Richard Proctor has worked with astronomers selected some of the best observations for this book. I love it. Okay, so what can we see about Mars? Let's turn to the page on Mars. It's a chart of Mars. We've got two circles next to each other here and they're kind of brown circles with these green seas that are carved into them and very delicately drawn in, actually. So what are we looking at here, Sean? We're looking at basically one of the first maps of Mars with any detail and with named features. Richard Proctor took this from drawings by an astronomer called Dawes. It's a multi-coloured lithograph print. It's a technique that was used in scientific diagrams like this. So yes, you're right Izzy, we've got brown land masses intersected with pale green basically seas. This is how the astronomers labelled these features that they could see through the telescope. The seas are named after astronomers under this system. Remember, Richard Proctor is the first person to create this detailed map, so he's got first dibs in his eyes on naming the features. These are dated from 1864 and 1865. Okay, so what are some of the names that we can see here? Well, under this system, which spoiler alert, it doesn't catch on, he's named after William Herschel Continent, the Dawes Ocean, the Lockyer land, the Cassini land, the Hook Sea Laplace land. He's kind of following the same pattern of naming craters and maria on the moon after prominent astronomers. And why didn't that catch on? Another system gained greater acceptance internationally, which is a system we know today, which is naming the features on Mars after figures in classical mythology. I'll take some pictures and we'll put them on our Instagram because they're really beautiful. Oh, we're taking out a big book now, so this is a bit of a much thicker book. It's a lovely dark blue with a leather bound and this sort of aged pages. We're now jumping to the year 1878. These are observations published in this book by Skiaparelli, who is a very famous name in the history of Mars observations. Oh, wow. So this is, this now looks far more like a graph almost. It's rectangular rather than seeing the circles we had previously. And again, you're just zooming into even more detailed names and features on Mars. You can see here a different system of naming features, they're basically named in Latin. So we have Cirtus Major and Cirtus Minor, which are probably quite familiar features nowadays. So basically this is the system for naming martian features that caught on internationally. Now, I'm really excited to get onto one of the other books that are in front of us to move away slightly from the mapping and talk about a very specific feature on Mars that one scientist in particular was convinced of. So can we talk about this middle sort of amber orangey book here? Who's written it and what does it detail? This book was written by Percival Lowell. It was published in 1896 and it's just called Mars. Very good. Okay. So what was Lowell particularly looking at? Because I think this one was perhaps controversial or groundbreaking at the time. It certainly excited a lot of interest at the time. Let's have a look at the table of contents. He's looking at general characteristics. He's looking at Mars, his atmosphere. He's looking at water on Mars, canals and oases. So half the book is about what he believes to be water on Mars. He's talking about the existence of the polar cat, which at the time was assumed to be made of water ice and not carbon dioxide as we know now. Under the section canals, he's talking about their artificiality and their development. Shall we take a closer look? Yes, absolutely. So I think that's the difference. Those maps that we were just looking at were detailing ancient places where once upon a time there would have been water, not saying like, yes, there's water there now. But that is very different from what Lowell is saying. And he is saying that actually there are current canals from his observations. He has discovered the canal systems on Mars. So let's look at some of his comments here. I've opened the page to plate 19, showing a whole network of nodes connected by lines. It's stretching across the disk of Mars. And this is the canal system that he is speculating along. And he's not the only person to speculate about it. And just to describe that image, if you imagine a sphere, that's Mars on its plate. And then you've got these sort of bigger pools of water then connected with lines, which kind of look like these cobweb systems. And that's what he's saying are canals. He set up his own private observatory in the United States. And from this observatory, he observed canals. He's made a whole list of supposed canals that he's been able to see 183 in total, he believes exist. Under the heading artificiality, he says, it is patent that here are phenomena that are passing strange to read their riddle. We had best begin by excluding what they are not as help towards deciphering what they are. So, you know, talking about the nature of all of these phenomena that he can observe. And there's just a lot of discussion about why we can see this pattern of supposed canals and what might be causing them. In a different part of the book, he's talking about seas and the fact that he can see different colours in the surface of Mars, you know, blue, green colours. What's it due to? Is it, for example, caused by areas of vegetation? Oh, yeah. Look at the very top of this page. It says, but if instead of being due to water, the blue green tint has been due to leaves and grasses. And he talks about here about as a place where autumn came on. Yes. It's basically not saying that the planet is blue or green. He's just saying that he can see changes in colour as he's observing the planet throughout the seasons. And sometimes Mars is closer to Earth than other times. There are optimum times for observing it. But as we will see in the next book, all of these observations, these impressions could be seen as highly subjective. Okay. I think that's a very polite way of saying that, so shall we look at this next book then? Who's written it? And what does it tell us? It's a lovely sort of A5 dark red leather band book. It's got beautiful details on the front. It almost reminds me of like the storm and banding of Jupiter. It's got lots of different colours woven into the front of it as well. So a very unique looking book. This is the house style for our in-house journal, Monthly Notices of the Royal Astronomical Society, which has been published for nearly 200 years now. This happens to be a volume from 1903. And we're going to turn the page to one article written by Edward Walter Maunder and his associate, J.E. Evans. E.W. Maunder was an astronomer. He's teamed up with a teacher from the Royal Hospital School in Greenwich to run some experiments on what can we really see on the surface of Mars. Okay, that's quite an interesting pairing. What did they do to maybe have a counter argument to what Lowell was saying? I'll read out the introduction. The experiments described in the following paper are undertaken in order to ascertain whether the impression of a network of fine lines, such as forms, what is now known as the canal system of Mars, could be produced upon entirely unbiased observers without those lines having a real objective existence. And should this prove to be the case, to find out the conditions most favourable for the creation of such an impression. So basically, they've taken a group of schoolboys, they've taken examples of observations of the planet Mars, printed them out on disks of paper that are maybe three to six inches in diameter. They've sat the boys at a certain distance from these disks, not told the boys anything about what they're looking at, but just asked them to sketch these disks in as much detail as possible. And they share the results of this experiment. There are some examples of the actual drawings made by the boys, and you can see they've tried their best and sometimes they draw canals and sometimes they don't. There's a lot of analysis and this is 1903, they are saying that there's a great deal of subjectivity in the way that people perceive features and sometimes canals might be suggested by the presence of dots or changes in shade in differing regions that abut each other, and it might not necessarily be canals. We can have a look at the final paragraph of this text. It seems a thousand pitties that all those magnificent theories of human habitation, canal construction, planetary crystallization and the like are based upon lines which are experiments compel us to declare non-existent, but with the planet Mars still left and the imagination unimpaired, there remains hope that a new theory no less attractive may yet be developed, and on a basis more solid than mere seeming. So based on this study it seemed to be an optical illusion. Thank you to Sean Frosta. This is the supermassive podcast from the Royal Astronomical Society with me, astrophysicist Dr Becky Smithurst and science journalist Izzy Clark. Has anyone seen the new livestream that's on ITVX? You're so excited about this, aren't you? I really am because I was having quite a boring Wednesday and suddenly all my Instagram was saying like, oh this has been launched and I know that there's been like NASA TV and all of these broadcasts, but like just sitting down on my sofa in my living room with a cup of tea just to be like, yeah where is the international space station actually? Like it was really relaxing. You know that like eight hours of a crackling fire or whatever it is you put on at Christen's time for Armbion. This is what's on in your living room for Armbion, isn't it? It absolutely is. But those who don't know by the way, this is a live stream from the international space station like looking down on the earth and it is just incredible to watch. You know you just got the view of a national in your living room. It's perfect. Exactly. I haven't looked at it yet. I do need to do this. So my social media streams were lighting up and WhatsApp groups and people saying, oh this is great ITVX thing. So you're recommending it, is it? Yeah, so it's kind of bizarre. So what they've done, it's on ITVX which is obviously an app on your TV and they've created Space Live as a channel. So if you go into the live section of ITVX there is now just this live stream from the international space station as it goes over earth. And it was lovely because when I was watching it, it had just come over the Caribbean and then into the corner of Brazil and then over the oceans and you see that moment of it crossing over into the dark side and the darkness of space is insane. And I don't think I'd ever really properly spent time looking at it for that long. If that makes sense, you're just like you wouldn't know that there's the earth underneath there. It's so so so dark. Yeah because unless you happen to be going over a city or something with lights, you just, yeah, it's just super dark. Yeah, it's very cool. In other exciting space news there has been a lot of Comet chat recently. Yeah, yeah. Are we excited for that? Have we seen it? I'm out of it Robert. So what do you know about Comet Lemon? Well, I know, so that there are two, there's Comet Swan and Comet Lemon and Comet Swan is a bit fainter and tougher. They're actually not far apart in the sky. I haven't seen either yet. I've tried. I did a little explain a video on it. I went out to look last night as we do this recording and didn't see it. I saw Cloud. It didn't rain. That was good. They were the previous days. I have been getting posts from people mostly in the north of England, Scotland with beautiful pictures of it. I even frustratingly saw someone, a post from a friend of mine, Sal Russell, who was in Berkshire. She had a lovely picture of it as well, which was coming through on this group chat and I haven't. So I am going to try. It is the, we're doing this recording on the 22nd of October. I'm going to try tomorrow night because apparently you can see it with your eye even just about. But perhaps it's one of those things that once you found it in an image and you know exactly where to look compared to what you've got in your foreground, like, oh, from this tree, it's just up at this angle or whatever. Maybe it's one of those things where breaking your phone out for like a 10 second night shot might help. I'll take that. I'll take my pair of binoculars. I'll take a glimpse. I just want to go and look instead of like sort of sitting there like last night in a van with a friend thinking, shall we go and look at it? You know, try again. Half an hour has gone. Time to go. The, um, the glamorous life, the glamorous life. Well, I was just thinking, I didn't explain a video and I have to go and make the effort to find it. So I just really want one clear night when I can actually see. Which direction is it roughly for people to look? It's, yeah. So I should explain all that. It's over in the western skies. So it's moving past, like, churras as we're recording this. It'll be around a bit longer if you get an outlight stelerium or something. It will show you where it is. It's reasonably bright. You know, if you can see it with your eye, the pair of binoculars, it should be dead easy if you know where to look. So, and you're right, Becky, of course, with a mobile phone, I'm very sure that a good mobile phone camera will pick it up too. It was odd. It was much brighter than expected. So when it was discovered, I think it was predicted to get to magnitude 10, which means you need a decent small telescope to see anything at all. You know, it won't be very impressive. And then it's 100 or so or several hundred times brighter than that. So it's gone through some kind of outburst or it's releasing a lot more material than people imagined it would. Which, and the reason that it gets brighter is because that material is lit up by the sun and that's how we see comets. So just maybe, just maybe, we'll see it. Are you going to try, is he? I mean, I'll try, but out of all of the locations that we're all crossing, we know that I've got the worst chance. The worst possible chance. You have the most likely to be shot. I'm like, I can try, but I know it's probably better for me just to stay on Instagram and scroll through. Everyone's better photos. Drive out of the light. No, exactly. And have a go. Yeah. It's so funny though, because like you say a little bit, it wasn't predicted to get this bright. I've basically been offline for like a month and I've come back today and been like, there's a comet. There's a guy, Will Gator, who took an amazing photo over Dartmoor, which was incredible. I think if you followed the UK Space Agency, the Spacegov UK, it's on their Instagram as well. It's a really lovely clear shot. He had the Northern Lights in the same shot, which I didn't see either. The magic shot. Which I had alerts. Didn't see those. Yeah. I mean, no, no, you need to get out London, Izzy. You need to have the feel the photons coming into your eyes. I know it, Robert. Don't I know it? Not permanently, just generally. But you have been away from like pollution recently, Izzy, right? Yes. I was very lucky and disappeared for a month to go to Peru, as you do. Para. Para. I went to Peru for a month with friends and we did this four day trek and on one of the first nights, we were camping at the base of a mountain and it's all covered in snow and all of this and it got really cold and we were all huddled in like a sort of the, what was the invertebrate, you know, the dining room. It was a tent where we ate food and my friend went out. She's like, oh, I'm going to get an early night, walked out, came back in and was like, oh my God, have you seen the sky? And so we all rushed out and I've never seen such a clear sky. Like, it was incredible because we were just in the middle of nowhere. The Milky Way just ran straight across this valley. I'll post a picture of it because it was breathtaking and hands down is the best night sky I have ever seen in my life. And probably we'll see. Yeah, it's exactly. So it was one of those moments here. Like, oh my gosh, this is what it's all for. Like, this is amazing. And even with just like a quick exposure on my smartphone, just so much came out as well. But you could see so much again with the naked eye. It was absolutely amazing. I'm glad you got to experience that. The southern sky when it's super dark, like, is a massive shock to us Northern Hemispheres. So it was Northern Hemispheres. It's just, there's just so many stars. You're just not prepared for the number of stars that you can see. My tiny brain could not compute. Right, shall we get back to Mars? And we've got some more listener questions here. So Becky, Adam has a question about living on Mars and says, Hi, I love the pod. If humanity is to eventually build a base on Mars, would it be closer to the poles, like closer to the water or ice, or closer to the equator? Neither. Most likely it's going to be in the mid-latitudes. So halfway between the poles and the equator. Like, really, the poles only have the water thing going for them in terms of pros versus cons of where you would want to start a base on Mars. The equator of the two of them would win out for the fact that you would have less extremes of temperature changes. You would have a consistent amount of sunlight as well to deal with, like, in terms of day to day or sol to sol as they call them on Mars. You would have much more balanced seasons than the poles would. And also, you'd have the easier launch from back off Mars as well, because of this idea of if you're at the equator, you got a boost from the planet's rotation, rather than poles, you don't have anything. You're just taking off straight upwards. It's the same reason why rockets on Earth are launched from near the equator, usually. So if you're not going to put yourself near the poles or the equator on Mars, then you're going to go for a compromise and go for the mid-latitudes. And you're going to want somewhere really flat for an easy landing as well, because you don't want a lot of rocks in the way that are going to knock over what are you landing. And one place that's actually been flagged for future missions by the likes of NASA and ESA is a place called Arcadia Planitia, which I think I'm pronouncing that right, but who knows. It's about 47 degrees north, so bang on mid-latitudes. And essentially, it's just this like big plain to the northwest of Olympus Mons, you know, the really massive mountain on Mars, the biggest natural system. And it's formed by lava flows from that whole volcanic range, like billions of years ago. And it ticks all the boxes of, you know, temperature seasons, sunlight, it's flat. But it also has water going for it as well, which is very exciting. And there's lots of evidence that there's a lot of subsurface water, Arcadia Planitia, a lot closer to the surface anyway than in other areas on Mars. So if you can get under the surface a little bit, you could have a reliable water source without having to schlep a lot of water to Mars. So it helps solve the issue of what you do to help keep your astronauts, I don't want to say fed, but watered, I guess. Okay, thank you. And Robert, Huvian Keith wants to know, with toxic materials like perchlorate, which are salts in soil on Mars, what are the tech challenges of producing drinkable water on Mars? Yeah, Keith, not straightforward, but so various research groups have actually looked at this, it transpires. And partly they were doing it because perchlorates are toxic, they're chemicals made with a molecule of oxygen, chlorine rather than four oxygens each, ionic, they make toxic compounds, they're not good for you. And also they're corrosive so they can damage your equipment as well. So there's a lot of interest in removing them. And they're also abundant in Martian soil. But research groups have looked at it partly to find ways to clean up water on earth. And I found two examples. I mean, the straight-fold thing you can do with the soil at least is to wash it out. But of course, if you do that, you're wasting the water and it just flushes it somewhere else. And that's the clean water you're trying to produce and use. So another approach is to use chemistry. And there was a group in 2021, took a fertilizer actually, and with molybdenum in, and clean contaminated water that way, or biology. And the other approach is to take what they suggested using genetically modified bacteria to do that. So in both cases, they make much less harmful byproducts and got clean water. Well, in the first case, I think it was a proper experiment. But the models both suggest they could get clean water as a result. So I think the answer is that it's feasible. I don't know about doing it on a large scale and how well that would work. And you're still going to have big areas of the planet, presumably they will have stuff in if you're just living in some small base and trying to live off the land and your surroundings. So, but it does say that it can probably be done. But I think describing as a tech challenge is exactly right. Yeah. I mean, the idea of introducing genetically engineered bacteria into Mars is like... It's going to say that's another level exactly. All of these things, this is where the ethics of this stuff are really, really important. Do we want to deliberately allow a genetically modified bacterium to spread across the Martian service? Let's see, no. Yeah. Hard no from us. Okay, good. Well, thank you for everyone who sent in questions. Keep them coming. You can send them to podcast at res.ac.uk. Find us on Instagram at supermassivepod or comment on the question thread if you're a member on the forum. So, Robert, let's finish with some stargazing. What can we see in the night sky this month? Yeah. So right now, obviously we're moving into November, it's autumn and so the autumn stars are pretty dominant and as the clocks have gone back by the time this goes out and the nights are also longer, it's relatively easy to look at both evening and even the morning stars as well. You don't have to get up stupidly early to see them. So, constellations wise, the square of Pegasus is really high up in the south by about nine o'clock and it's... I think I've mentioned this before, it's shared the constellation of Andromeda 2. It's distinguished by being a big square in the sky with not many stars in it and the number you can see is a good test of how dark your sky is. So from London, really, it's quite possibly none. If you go somewhere much darker, then you might see a few more. And if you follow the right hand side of the square down a long way, you come to this curiosity of the southernmost bright star, first magnitude star visible in the UK called Fomalope and that's just a nice thing to look out for. Say, okay, that's the southernmost bright star I can see. But to the east of it, you've got the famous Andromeda and the famous Galaxy, which is pretty much the furthest object that I can see, two and a half million light years away and then also stars like Almak, Gamma Andromedy, which you can just look up on a star chart, which if you look at it with a small telescope, you see a bright yellow star on a deep blue companion. It's very, very pretty. The deep blue companion is actually three stars, but you can't so easily see those in the solar system. Mercury is going to be around towards the end of November in the morning sky. And on the 24th, it's actually near Venus. So you've got a nice pairing there and Venus conversely is actually about to disappear from view. It's going to cover up, it's going behind or in front of the sun, but it'll be out of our out of our skies for a couple of months or so. I've been up recently where I've just seen it in the morning. So it's sort of been around 6am and you just see it, it's just like, oh, just like a nice little start to the day, just being able to start it with Venus. So it's so pretty and you think it'll be there forever because it's there for months and months and months and then it goes and it goes into the evening sky instead, but it'll be back. It's like the only thing that I look forward to when the clock goes back in October is those like catching those kind of things in the morning when you wake up. Everything else I like about it. Like the Venus catching Venus in the morning. Venus offsets it, it does, doesn't it? That's why we need clear skies in the morning. Anyway, so to add a bit more, Saturn's still really good in the evening. Those rings are still not too far away from edge on. They're not, it's not full Saturn yet really. And Jupiter starts to become easier to see as well as the month goes on. So you start to see it earlier in the night. You know, it's been really a morning object and it'll be at its best in January. And there are also two low level meteor showers this month, the southern and northern turrets, which means that the meteors appear to come from tourists, the constellation. And they both appear to originate from the same part of the sky. Neither of them has a lot, right? Five an hour a peak and you'll probably see two or three. So that's not, not that exciting, but they do tend to be showers that produce fireballs, which are very bright meteors, the sort of thing that gets everybody looking up excited. So, you know, it's impossible to know when they're going to happen. It could be absolutely any time, but you might just have a better chance of seeing one in the month of November than other times. Plus there is, it's the peaks on the supermoon night as well, so that you've got an extra bright night. So yeah, moon is not helpful. Yeah, it's not something to specifically go out and look for. But if you happen to be looking up and you happen to see a giant bright fireball, no, that's what it probably was rather emailing your friendly neighbour. No, no, no, definitely. I don't stick out for three hours just looking for these. If you're out looking at the stars anyway, it's a nice bonus. I've obviously added, you know, if you see one of these or you happen to get a picture of one, obviously tag us on Instagram. That's always nice. You know, we love to see these pictures from our listeners. Oh, lovely. Well, thanks for that. And I think that's it for this month. We'll be back with a bonus episode in a few weeks time. And don't forget, you can join the Supermassive Club. We've got the Book Club on there, so everyone's sharing their stargazing photos and sharing questions as well. So it's a lovely little place that actually... Yeah, it's nice to see that community growing. Yeah. So contact us if you try some astronomy at home either through the Supermassive Club or it's at SupermassivePod on Instagram or you can email any questions you might have to podcast at rs.ac.uk and we'll try and cover them in a future episode. But until next time, everybody, happy stargazing.