#453: Starliner Suit Dilemma, Iron Rain on WASP 76b & Kuiper Belt Mysteries

[00:00:00] [SPEAKER_01]: Hello again, thank you for joining us. This is Space Nuts. My name is Andrew Dunkley and I'm glad

[00:00:05] [SPEAKER_01]: you could join us yet again. Coming up on this episode, Starliner. Yes, we have another update.

[00:00:11] [SPEAKER_01]: This is a really strange problem. A really strange problem. Nothing to do with noises coming from the

[00:00:17] [SPEAKER_01]: inside of the Starliner either. It's a completely different problem. They probably never anticipated.

[00:00:24] [SPEAKER_01]: We're also going to visit planet WASP 76b because it's got rain that you never want to get involved

[00:00:32] [SPEAKER_01]: in unless you love heavy metal. The Kuiper Belt is busier than we thought and they think they know

[00:00:40] [SPEAKER_01]: where all the water went on Mars. It's not here but it's somewhere. We'll tell you all about it on the

[00:00:46] [SPEAKER_01]: current episode of Space Nuts.

[00:01:04] [SPEAKER_01]: And to tell us all about it is the man himself, Professor Fred Watson. Hello Fred.

[00:01:14] [SPEAKER_00]: Hello Andrew. It's good to be the man himself. I appreciate that very much.

[00:01:18] [SPEAKER_00]: Better than being the man of somebody else. Yes, it probably happens sometimes.

[00:01:24] [SPEAKER_01]: No, good to see you too. We should get stuck straight into this because we have got a lot

[00:01:30] [SPEAKER_01]: to get through and some of these stories are extraordinary. We talked about Starliner last week

[00:01:37] [SPEAKER_01]: and the issue of that noise coming from the inside which turned out to be feedback on their audio

[00:01:44] [SPEAKER_01]: system which is not a big problem. You just turn off the speaker or the microphone or both.

[00:01:52] [SPEAKER_01]: But the new problem is one involving the two astronauts who are basically stuck

[00:02:00] [SPEAKER_01]: on the International Space Station because of the technical hitches that the Boeing Starliner

[00:02:06] [SPEAKER_01]: is suffering. We're talking about Butch Wilmore and Suni Williams. Now they're looking at how

[00:02:14] [SPEAKER_01]: they're going to get them back. There's talk of getting them back sometime next year but a new

[00:02:20] [SPEAKER_01]: problem has arisen as a consequence of one of the potential solutions. That's correct.

[00:02:28] [SPEAKER_00]: So the potential solution which is what's going to happen and some of this may have already happened

[00:02:33] [SPEAKER_00]: by the time this episode goes to air in particular the Starliner itself might have come back empty

[00:02:40] [SPEAKER_00]: which is the plan at the moment. But the problem is when these two Boeing Starliner astronauts

[00:02:48] [SPEAKER_00]: Butch and Suni as you've mentioned, when they do finally come back it will not be on a Starliner

[00:02:56] [SPEAKER_00]: spacecraft. They will be coming back in a SpaceX Crew Dragon and the space suits that you use on a

[00:03:04] [SPEAKER_00]: Starliner are not the same as the ones that you use on a Crew Dragon and they're incompatible.

[00:03:11] [SPEAKER_00]: So what it means is that when their ferry home is launched up to the Space Station

[00:03:20] [SPEAKER_00]: this will be the Crew Dragon that is going to bring them back home next February. It's going up there

[00:03:24] [SPEAKER_00]: sometime we think this month, September with two empty seats in it. They will also have to send up

[00:03:32] [SPEAKER_00]: two empty space suits for Butch and Suni. The reason why it's tricky is because

[00:03:43] [SPEAKER_00]: once that spacecraft arrives, that's the Crew Dragon later this month,

[00:03:49] [SPEAKER_00]: once that arrives the problem is solved because NASA will send up their correct space suits with it.

[00:03:56] [SPEAKER_00]: But if there's an issue before then, an issue in which the International Space Station has to be

[00:04:03] [SPEAKER_00]: evacuated and that's always at the back of people's minds you've got to be ready to get off just in

[00:04:09] [SPEAKER_00]: case something goes catastrophically wrong. Like a big bit of space junk colliding with it

[00:04:14] [SPEAKER_00]: or something like that. If they had to return there is a Crew Dragon docked with the Space

[00:04:22] [SPEAKER_00]: Station at the moment which will carry the current crew of four astronauts in what's called the Crew

[00:04:29] [SPEAKER_00]: 8 mission back to Earth and it will have room for Suni, Williams and Bruce Wilmore. It will have

[00:04:38] [SPEAKER_00]: on a cargo pallet underneath the seats. Oh what? Are you kidding? That's right, yeah. It's like

[00:04:46] [SPEAKER_00]: riding in the back of the U. Oh my gosh. So they're going to be huddled under there but the

[00:04:52] [SPEAKER_00]: problem is that their space suit designed for the Starliner won't work so they're going to have

[00:05:01] [SPEAKER_01]: to do it without the space suit. So they have to leave them behind? They have to leave them

[00:05:06] [SPEAKER_00]: and go home in their undies? Probably a little bit more than their undies but they will not be

[00:05:12] [SPEAKER_00]: protected by a space suit which has been standard practice for many decades in both NASA and Ros

[00:05:19] [SPEAKER_00]: Cosmos flights that you don't land or launch without your space suit on just in case something

[00:05:24] [SPEAKER_00]: goes wrong and the spacecraft depressurizes. Yes, yes. Wow. But they will be in that situation.

[00:05:31] [SPEAKER_00]: It's likely that, you know, I mean it would have to be a real emergency situation for them to do

[00:05:36] [SPEAKER_00]: that and you would hope that everything would work out all right. Yeah. But it is, yes, it's putting

[00:05:42] [SPEAKER_01]: them in an interesting position. So at the very best they get to come home on February next year

[00:05:54] [SPEAKER_01]: with alternative space suits but in an emergency could end up having to come back without space

[00:05:59] [SPEAKER_00]: suits. Wow. Yeah, only if that emergency occurs before the Crew 9 spacecraft gets there. So yeah,

[00:06:07] [SPEAKER_00]: so it's a short window when there is this situation but it is a situation that

[00:06:12] [SPEAKER_01]: has real risks attached to it. Yeah, gosh, wouldn't you love to be in a room

[00:06:17] [SPEAKER_01]: just watching the people trying to figure all this out? How are we going to do this? What are

[00:06:21] [SPEAKER_01]: we going to do? Oh hang on there's a new problem. Oh, you know, we set that pallet of bricks up,

[00:06:26] [SPEAKER_01]: can we use the pallet? That's it, yeah. Never throw away a good pallet. No, no, that's right,

[00:06:36] [SPEAKER_01]: they're very useful. People make Christmas trees out of them, you know. Well I'm sure they do. Yeah,

[00:06:42] [SPEAKER_01]: my son's got a Christmas tree made out of an old pallet. Yeah, looks nice. Wow, so that's the state

[00:06:49] [SPEAKER_01]: of play as we speak but like we're recording ahead of time to cover a trip of mine so

[00:06:55] [SPEAKER_01]: it may well be a different story by the time this comes out but that's a unique problem. I don't

[00:07:01] [SPEAKER_01]: think I've ever heard of that one before. Fascinating. All right, well we'll try to

[00:07:07] [SPEAKER_01]: keep you informed but time might work against us over the coming weeks but yes, it's been a

[00:07:13] [SPEAKER_01]: fascinating, it's been a soap opera really hasn't it? A little bit, yes. Are you sure about that?

[00:07:19] [SPEAKER_01]: Yeah, Boeing wouldn't like it if we called that but I think you're right. Yeah,

[00:07:23] [SPEAKER_01]: yeah, well it's better than a horror movie. Yes, exactly. Okay, let's move on to our next story

[00:07:29] [SPEAKER_01]: and this one takes us a long way away to a planet called Wasp 76b. It was only discovered

[00:07:38] [SPEAKER_01]: what 11 years ago but it's been the subject of a lot of study and they are learning more and more

[00:07:45] [SPEAKER_01]: about it and what's really good is they've been able to actually optically observe this one,

[00:07:50] [SPEAKER_01]: I think Fred. It's a stinking hot place though. Australians would like it. We like the heat.

[00:07:57] [SPEAKER_00]: I'm not sure you'd like this much though. So yes, it is a star that is very, very close,

[00:08:06] [SPEAKER_00]: sorry, a planet that is very close to its parent star. The parent star is Wasp 76

[00:08:11] [SPEAKER_00]: and in the normal convention you put a b after it for the first planet that's discovered around it

[00:08:16] [SPEAKER_00]: and it's Wasp 76b which is the planet that we're talking about. It's about something like

[00:08:25] [SPEAKER_00]: getting on for twice the size of Jupiter so it's what we call a hot Jupiter but it is very,

[00:08:32] [SPEAKER_00]: very close to its parent star. Distance is measured almost in centimeters, not quite

[00:08:38] [SPEAKER_00]: but it's actually about 40 million kilometers from its parent star. Now that sounds like a lot

[00:08:47] [SPEAKER_00]: but it's such a close place to its parent star that it goes round something like once every

[00:08:58] [SPEAKER_00]: two days or thereabouts. It's a ridiculously short length of time, I can't find the exact figure

[00:09:03] [SPEAKER_00]: but it's that sort of length of time. It absolutely whizzes around. It's actually 1.8

[00:09:11] [SPEAKER_00]: Earth days and so that means a number of things. First of all, because the star and its planet are

[00:09:17] [SPEAKER_00]: so close together, the star is more massive. It's actually I think more massive than the sun,

[00:09:24] [SPEAKER_00]: about one and a half times the mass of the sun. What that means is that the planet itself is

[00:09:30] [SPEAKER_00]: locked tidally so it always faces its parent star, Wasp 76. It's always got a hot side and

[00:09:40] [SPEAKER_00]: not exactly a cold side but a cooler side. Now on the hot side you've got a temperature high enough

[00:09:49] [SPEAKER_00]: to not just melt iron but vaporize iron. So there is iron vapor in the atmosphere of this planet.

[00:09:57] [SPEAKER_00]: It's about 2,400 degrees Celsius or about 4,350 degrees Fahrenheit on the hot side. Now that vapor

[00:10:08] [SPEAKER_00]: is whizzed around by really strong winds that exist on Wasp 76b. Those winds are generated by

[00:10:17] [SPEAKER_00]: the sheer heat of the atmosphere being so close to its parent star. So this vaporized iron whizzes

[00:10:25] [SPEAKER_00]: around to the back side of the planet, the night side, the permanent night side and there it gets

[00:10:32] [SPEAKER_00]: cool enough to be not vapor but liquid. And so it condenses into droplets of iron rain. So iron rain

[00:10:44] [SPEAKER_00]: to me does not sound that good. Yes, it's cooler but not that much cooler. You'd have to come up

[00:10:52] [SPEAKER_00]: with a really good umbrella. Yeah, I think you would too. But that's only part of the story.

[00:11:01] [SPEAKER_00]: And I should say that this planet has become almost the personal property of scientists at

[00:11:08] [SPEAKER_00]: the University of Geneva in Switzerland. They've done a lot of serious research on this planet and

[00:11:14] [SPEAKER_00]: it's a release from them that's really discovered these very hot winds of vaporized iron.

[00:11:23] [SPEAKER_00]: It's such an extreme planet that is well worth studying because it gives you an idea of how

[00:11:29] [SPEAKER_00]: extreme things can be and sheds light on other planets which are also in our part of the universe.

[00:11:38] [SPEAKER_00]: So just an aside, the work that's being done in Geneva is using a telescope that we Australian

[00:11:45] [SPEAKER_00]: astronomers also have access to, the ESO, European Southern Observatory, very large telescope down

[00:11:50] [SPEAKER_00]: in Chile. There's an instrument on that that is, excuse me I just have to press a button on my

[00:11:59] [SPEAKER_00]: watch here, sorry about that. There's an instrument on that that was actually built by the University

[00:12:05] [SPEAKER_00]: of Geneva. So that's what they're using to make these measurements of the vaporized iron whizzing

[00:12:10] [SPEAKER_00]: around the planet. But wait, there's more because some research done I think by the same group

[00:12:20] [SPEAKER_00]: and published a little while ago actually, we missed this story back in April. It's work that

[00:12:28] [SPEAKER_00]: concerns what might happen to those iron droplets in the atmosphere. Yes you've got iron rain.

[00:12:35] [SPEAKER_00]: Now when we have rain on our planet you get phenomena like rainbows and things of that

[00:12:43] [SPEAKER_00]: sort. And there's evidence that phenomena like that are occurring on WASP-76b,

[00:12:53] [SPEAKER_00]: not specifically rainbows but rainbow-like phenomena and in particular it's something

[00:12:58] [SPEAKER_00]: called a glory which most of us have actually seen believe it or not. And I'm sure you have

[00:13:04] [SPEAKER_01]: Andrew when you look at the... Does it happen in the morning?

[00:13:10] [SPEAKER_00]: That's a different thing altogether.

[00:13:15] [SPEAKER_00]: And I should explain to non-Australian listeners that there is a plant called a morning glory which

[00:13:22] [SPEAKER_00]: blossoms in the morning. Yeah. I'm sure that's what you were talking about Andrew. Absolutely of course.

[00:13:29] [SPEAKER_00]: No, a glory is something, I was just going to say you've almost certainly seen it because

[00:13:36] [SPEAKER_00]: if you've looked out of the window of an aircraft that's flying over cloud, you will often see a

[00:13:43] [SPEAKER_00]: little shadow of the aircraft from if you're on the right side of the plane with circular colored

[00:13:48] [SPEAKER_00]: rings around it. And that's called the glory. It occurs because light is being diffracted

[00:13:54] [SPEAKER_00]: by the rain droplets in the clouds and that diffraction process splits it up into its

[00:14:01] [SPEAKER_00]: rainbow colors and you see this succession of rainbow rings. Similar to something you might

[00:14:08] [SPEAKER_00]: have seen today if you've been looking in the right direction which is called a pollen corona.

[00:14:13] [SPEAKER_01]: Yes, I should go out there and try and take another photo. Yeah, you got a lovely photo of

[00:14:18] [SPEAKER_01]: one last year. And a few years back when you first told me about them and I took up the challenge

[00:14:24] [SPEAKER_01]: and I went outside and I couldn't see it because it was so bright but the camera picked it up

[00:14:30] [SPEAKER_01]: and got a beautiful photo of a pollen corona. Yeah, they're quite strong. Which they are and

[00:14:36] [SPEAKER_00]: the corona is a little bit different because it's around the sun when you're looking towards the sun

[00:14:42] [SPEAKER_00]: but it's still caused by this same diffraction effect and a glory... We've got a very windy day

[00:14:47] [SPEAKER_01]: today and it's sunny and the sun is just in the perfect position so I might go out and take a

[00:14:53] [SPEAKER_00]: snapshot. Are you going to do it now? Not right this minute, that's good. I'm glad to hear that

[00:15:00] [SPEAKER_00]: because otherwise I would have had to waffle on for a little while and I might much rather be

[00:15:04] [SPEAKER_00]: talking to you. So yeah, but you're familiar I'm sure with that phenomenon of looking down

[00:15:11] [SPEAKER_00]: from an aircraft, you see the clouds, you often see the shadow of the plane and around it is this

[00:15:17] [SPEAKER_00]: this succession of colored rings. We think that might be occurring on WASP-76b and the reason why

[00:15:27] [SPEAKER_00]: scientists, as I said at the University of Geneva and actually the Institute of Astrophysics and

[00:15:36] [SPEAKER_00]: Space Science in Portugal, there's a group involved with it there too, they have worked out from

[00:15:48] [SPEAKER_00]: asymmetries in what we call an asymmetric light curve. The light curve is the way the light of

[00:15:54] [SPEAKER_00]: this planet varies as it goes around its parent star and you expect that to be more or less

[00:16:00] [SPEAKER_00]: symmetrical because when it is on one side of the star it's shining with a particular brightness

[00:16:05] [SPEAKER_00]: and it should be the same when it's on the other side of the star but they've discovered

[00:16:09] [SPEAKER_00]: it's not, there are asymmetries in it so it's not symmetrical and these scientists are putting

[00:16:14] [SPEAKER_00]: that down to the existence of a glory in the clouds of WASP-76b which is quite an extraordinary

[00:16:22] [SPEAKER_01]: claim really and an extraordinary discovery. What would an iron rain rainbow look like?

[00:16:29] [SPEAKER_00]: Pretty hot I think, no it's a good question. So it depends on the transparency of the droplets

[00:16:39] [SPEAKER_00]: which I find it hard to get my head around transparent iron droplets. Yeah me too.

[00:16:47] [SPEAKER_00]: Because you think of iron as being a metal but if it's heated enough and it's on the point of

[00:16:54] [SPEAKER_00]: becoming vapor the droplets might be quite transparent and would give you these various

[00:17:00] [SPEAKER_00]: phenomena, refraction and diffraction. But it's something yes we need to look into and I can

[00:17:06] [SPEAKER_00]: hear you typing on your keyboard so you're probably doing it as we speak. I'm trying to

[00:17:09] [SPEAKER_01]: see whether or not there is a colour for iron vapor but it's not something that's

[00:17:16] [SPEAKER_01]: been searched for very much so there's not many references to it. But yeah it might be something

[00:17:22] [SPEAKER_01]: for another day. Indeed. Yeah great story though, so much to learn from WASP-76b and was I right

[00:17:30] [SPEAKER_01]: it's one that has been observed optically?

[00:17:35] [SPEAKER_00]: I think it's still yes but not directly. I think what has been measured is the way the

[00:17:42] [SPEAKER_00]: combined brightness of the star and the planet change as it goes around in its orbit.

[00:17:47] [SPEAKER_00]: Right. I think that's the optical observations that have been made. Okay very good. If you'd

[00:17:51] [SPEAKER_01]: like to read up on that story you can find out more about it, the iron rains of WASP-76b

[00:17:59] [SPEAKER_01]: in the journal Astronomy and Astrophysics. This is Space Nuts, Andrew Dunkley here with

[00:18:05] [SPEAKER_02]: Professor Fred Watson. Okay we checked all four systems and in with the girls. Space Nuts.

[00:18:14] [SPEAKER_01]: Oh that was a short break. Okay I was going to take a breath. Yeah you don't get time for breaths

[00:18:22] [SPEAKER_01]: in this. No no. Our next story takes us to the Kuiper Belt. Now what's interesting about the

[00:18:29] [SPEAKER_01]: Kuiper Belt is well just about everything about it but now they think it might actually be bigger,

[00:18:35] [SPEAKER_00]: deeper and more occupied than we first thought. Fascinating. Yeah that's right. So a very nice

[00:18:43] [SPEAKER_00]: combination of astronomical infrastructure here because this is work that combines the Japanese

[00:18:54] [SPEAKER_00]: Subaru telescope on Mauna Kea in Hawaii which is an eight meter class telescope named Subaru

[00:19:00] [SPEAKER_00]: after the Japanese name for the Pleiades, the seven sisters. And the work has been done in

[00:19:08] [SPEAKER_00]: collaboration with the mission scientists of New Horizons, the spacecraft that is leaving the solar

[00:19:15] [SPEAKER_00]: system, one of five that's leaving the solar system. Now you and I spoke about New Horizons

[00:19:20] [SPEAKER_00]: not very long ago because it's used its cameras to measure the night sky brightness. So it's just

[00:19:29] [SPEAKER_00]: the brightness of the sky because it's night all the time out there. This is 60 astronomical units

[00:19:35] [SPEAKER_00]: from the Earth which is where the spacecraft is at the moment. Remember one astronomical unit is

[00:19:40] [SPEAKER_00]: 150 million kilometers, it's the distance between the Earth and the Sun. So a long long way,

[00:19:47] [SPEAKER_00]: 60 times further away from the Sun than the Earth is. And the New Horizons flew by Jupiter in 2015,

[00:19:56] [SPEAKER_00]: sorry flew by Pluto 2015, flew by Arrokoth a couple of years later, a distant Kuiper Belt object,

[00:20:04] [SPEAKER_00]: and used its cameras to very good effect. It's got fantastic cameras on board. Now the mission team

[00:20:10] [SPEAKER_00]: of New Horizons, which is still scanning for new Kuiper Belt objects to try and divert New

[00:20:17] [SPEAKER_00]: Horizons 2 to have a close look at, given the limited fuel that they've got on board New Horizons

[00:20:24] [SPEAKER_00]: in order to do that diversion, they've got to be fairly careful about what they choose. And at the

[00:20:30] [SPEAKER_00]: moment there are no candidates. And part of the problem for that is that whilst New Horizons has

[00:20:35] [SPEAKER_00]: got, as I said, superb cameras on board, they're not wide-angle cameras, they're not the kind of

[00:20:40] [SPEAKER_00]: camera that you want to use for searching for potential candidates. And for that you need a

[00:20:45] [SPEAKER_00]: wider field of view, and it turns out that back here on Earth, back home on our sunny planet as

[00:20:52] [SPEAKER_00]: it is for me now, the Subaru telescope has a wide-field camera which is capable of detecting

[00:21:01] [SPEAKER_00]: these faint objects at these great distances from the Earth. And so the combination of the two of

[00:21:08] [SPEAKER_00]: them has been to identify some Kuiper Belt objects that New Horizons can sort of foam in on, at least

[00:21:14] [SPEAKER_00]: with its camera, not necessarily being diverted there, but they can have a look at it with the

[00:21:19] [SPEAKER_00]: New Horizons camera because it's much closer than Subaru is. Subaru can find these objects and say

[00:21:24] [SPEAKER_00]: there's a target that you need to look at, and New Horizons can then have a close look at it.

[00:21:29] [SPEAKER_00]: And the upshot of all this is that it looks as though the Kuiper Belt has more of these icy

[00:21:37] [SPEAKER_00]: asteroids in it than we thought. Basically, we thought that the Kuiper Belt ran out of steam

[00:21:43] [SPEAKER_00]: roughly at the distance where New Horizons is, 60 astronomical units from the Sun.

[00:21:49] [SPEAKER_00]: But it turns out that there's more. They found a population of these things beyond,

[00:21:57] [SPEAKER_00]: in the region of a dozen I think or so that have been found so far, perhaps a few more than that.

[00:22:02] [SPEAKER_00]: But these kind of cluster around 80 astronomical units from the Sun. So another quarter, sorry,

[00:22:11] [SPEAKER_00]: third of the distance away, you've got another group of these objects, which is something that

[00:22:17] [SPEAKER_00]: was not known. We do know that the icy asteroids beyond Neptune, which we call trans-Neptunian

[00:22:25] [SPEAKER_00]: objects, we know that they do group into different groups. And the Kuiper Belt is the innermost of

[00:22:29] [SPEAKER_00]: those groups. There are some things called scattered disk objects, which are much further

[00:22:35] [SPEAKER_00]: away. And I don't think that's what we're looking at though. We're not looking at the scattered disk,

[00:22:40] [SPEAKER_00]: we're looking seriously at the Kuiper Belt and finding that there's more in it than we thought

[00:22:44] [SPEAKER_00]: there were. And the conclusion to be drawn from that is that perhaps the protoplanetary disk

[00:22:52] [SPEAKER_00]: around the Sun when the planets were being formed was bigger than what we thought it was,

[00:22:57] [SPEAKER_00]: because we're finding debris out there that is almost certainly left over from that process,

[00:23:02] [SPEAKER_01]: but it's further away from the Sun than we expected. Okay. Now someone's got to think of it.

[00:23:08] [SPEAKER_01]: So I'll just ask if this is the case and we've got a bigger Kuiper Belt than we thought,

[00:23:13] [SPEAKER_01]: and there's much more junk out there from our solar system origins, could planet nine be a

[00:23:26] [SPEAKER_00]: reason for that? No, it's a great question. And the thinking with planet nine is that it

[00:23:33] [SPEAKER_00]: is much further away, perhaps twice that distance. But we don't... The thinking about

[00:23:41] [SPEAKER_00]: the hypothetical planet nine is that it affects these objects, these really most distant objects

[00:23:50] [SPEAKER_00]: in the trans-Neptunian region beyond Neptune, and it changes their orbits. That's the thinking

[00:23:56] [SPEAKER_00]: why some astronomers believe that planet nine exists. Some believe it doesn't exist as well.

[00:24:02] [SPEAKER_00]: I talked to one earlier in the year who was a planetary scientist who said,

[00:24:06] [SPEAKER_00]: no, it's pie in the sky. So you've got very different opinions there. But anyway,

[00:24:15] [SPEAKER_00]: that idea of planet nine being part of this new population of Kuiper Belt objects,

[00:24:22] [SPEAKER_00]: I think it's too far away to be included in what is being considered here.

[00:24:27] [SPEAKER_01]: Yeah, but it's certainly a great discovery that the Kuiper Belt might be bigger and

[00:24:33] [SPEAKER_01]: contain a lot more objects than we ever thought. So probably a lot more to learn and a lot more

[00:24:38] [SPEAKER_01]: to talk about going forward. And you can find out more about it when they publish,

[00:24:44] [SPEAKER_01]: I think there's a couple of papers on this, which will be published in the Planetary Science Journal.

[00:24:55] [SPEAKER_01]: Space nuts. Okay, moving on from the Kuiper Belt to a little rock closer to its parent star,

[00:25:03] [SPEAKER_01]: and that is a planet called Mars. And one of the things that gets people scratching their heads

[00:25:10] [SPEAKER_01]: about Mars is what happened to the water? What happened to the atmosphere?

[00:25:14] [SPEAKER_01]: What happened to all the dogs and cats that lived there?

[00:25:19] [SPEAKER_01]: But we may have an answer on the water issue. Yes, that's right. And again, this is a really

[00:25:25] [SPEAKER_00]: nice collaboration between very well known facilities, and both NASA facilities in this case.

[00:25:33] [SPEAKER_00]: NASA has spacecraft in orbit around Mars. It's got a number of spacecraft in orbit around Mars.

[00:25:38] [SPEAKER_00]: But one of them is MAVEN, which is an acronym for Mars Atmosphere and Volatile Evolution.

[00:25:47] [SPEAKER_00]: So as the name implies, MAVEN is looking at the atmosphere of Mars. And one of the reasons why

[00:25:54] [SPEAKER_00]: MAVEN was sent to Mars, and in fact, it's probably the best part of a decade ago,

[00:25:57] [SPEAKER_00]: it's quite a long time ago. The reason for that was to look at exactly what we're talking about,

[00:26:03] [SPEAKER_00]: the prospects of atoms leaving Mars' atmosphere. And I guess the main culprit,

[00:26:14] [SPEAKER_00]: especially if you're thinking about water, is hydrogen, because water is hydrogen and oxygen.

[00:26:20] [SPEAKER_00]: We think one of the reasons why Mars has lost its water is because of the dissociation of water

[00:26:31] [SPEAKER_00]: into hydrogen and oxygen. And the hydrogen basically escapes from Mars' atmosphere. And

[00:26:37] [SPEAKER_00]: that has been kind of demonstrated already by MAVEN. But there is an issue with the observations.

[00:26:47] [SPEAKER_00]: And it is because during the Martian, I think it's the Northern Hemisphere winter,

[00:26:55] [SPEAKER_00]: it's Mars, just to step back a minute, Mars has an orbit, which is much less circular than the

[00:27:04] [SPEAKER_00]: Earth's orbit. It's highly elliptical, quite elongated. So for part of the year,

[00:27:11] [SPEAKER_00]: Mars is significantly further away from the sun than it is at other times of the year.

[00:27:18] [SPEAKER_00]: And what happens is this spreading of hydrogen into space from Mars' upper atmosphere,

[00:27:26] [SPEAKER_00]: actually in that period when Mars is a long way away, it becomes too faint for MAVEN to see.

[00:27:34] [SPEAKER_00]: And that is why the mission scientists have turned to the Hubble Space Telescope,

[00:27:40] [SPEAKER_00]: another NASA facility, which can see Mars pretty clearly and is able to actually provide data on

[00:27:48] [SPEAKER_00]: the hydrogen escaping from Mars back to 1991, actually. And in fact, I've just seen that MAVEN

[00:27:56] [SPEAKER_00]: arrived at Mars in 2014. So my guess of it being the best part of 10 years was right on the line.

[00:28:02] [SPEAKER_00]: Spot on. Now there's a subtlety to this though, that I just must mention because it's not just

[00:28:07] [SPEAKER_00]: the ordinary hydrogen that the Hubble is helping out with. It is deuterium, the heavy hydrogen. And

[00:28:15] [SPEAKER_00]: you and I have spoken about this before, that heavy hydrogen has an additional neutron, which means

[00:28:23] [SPEAKER_00]: its mass is about twice, mass of a hydrogen atom is about twice what it is normal hydrogen. We call

[00:28:30] [SPEAKER_00]: it deuterium. We sometimes call it heavy hydrogen, but we call it deuterium. If that combines with

[00:28:37] [SPEAKER_00]: oxygen, then you get heavy water. And it's the ratio between these two that is the clue to what

[00:28:45] [SPEAKER_00]: might have happened to Mars' oceans in the distant past. And so these scientists, what they're doing

[00:28:51] [SPEAKER_00]: is they're looking at the ratio of hydrogen to deuterium in the gas that is leaving Mars at

[00:28:58] [SPEAKER_00]: present. And from that, it's a bit like carbon-14 dating, from that they can work out

[00:29:03] [SPEAKER_00]: how early in Mars' history that water left, how long it's been being lost from Mars.

[00:29:13] [SPEAKER_01]: Oh, so they can do the calculations backwards and see how long...

[00:29:17] [SPEAKER_00]: That's right.

[00:29:18] [SPEAKER_00]: The calculations back in time, that's it.

[00:29:20] [SPEAKER_01]: Incredible. And so they've basically confirmed that it's this deuterium that's

[00:29:29] [SPEAKER_01]: zipping out into the... No, it's heavier, isn't it? So it's...

[00:29:34] [SPEAKER_00]: Yes. So probably, yeah, it's the heavy stuff probably stays closer to Mars than the light

[00:29:41] [SPEAKER_00]: stuff. But you've got to... It's the ratio of the two of them that you're really interested in.

[00:29:46] [SPEAKER_00]: Yeah. And that's what's telling the tale.

[00:29:49] [SPEAKER_00]: That is what's telling the tale. That's right. As, is it phys.org puts it,

[00:29:54] [SPEAKER_00]: measuring the ratio today gives scientists a clue as to how much water was present during

[00:29:58] [SPEAKER_00]: the warm-wet period on Mars. Fascinating.

[00:30:02] [SPEAKER_01]: Yeah. Wow. All right. So we... Yeah, it's been sort of zipping off into the ether, basically.

[00:30:10] [SPEAKER_01]: Yeah.

[00:30:10] [SPEAKER_01]: That's right. Yes.

[00:30:12] [SPEAKER_01]: And it's still happening by the description you gave.

[00:30:16] [SPEAKER_00]: That's correct. Yes. Yeah. Look, I'll read the next sentence to that because it's beautifully

[00:30:20] [SPEAKER_00]: put by phys.org, by studying how these atoms currently escape, they can understand the

[00:30:25] [SPEAKER_00]: processes that determine the escape rate over the last four billion years and thereby extrapolate

[00:30:30] [SPEAKER_00]: back in time. Very nicely done. Indeed. I think actually that might be a NASA press release

[00:30:36] [SPEAKER_01]: rather than a phys.org article. Okay. But you can read it on phys.org. You can also read the study

[00:30:43] [SPEAKER_01]: in Science Advances. That brings us to the end of this episode. Thank you so much, Fred.

[00:30:51] [SPEAKER_01]: Oh, it's a pleasure, Andrew. We should do it again sometime.

[00:30:54] [SPEAKER_01]: We probably will in a few minutes. Well, soon, in a few days. Yes. Thank you, Fred. Professor

[00:31:01] [SPEAKER_01]: Fred Watson, astronomer at large, and thanks to Hugh in the studio for being Hugh in the studio

[00:31:06] [SPEAKER_01]: and no one else can be Hugh in the studio. I can tell you that for free. And from me,

[00:31:12] [SPEAKER_01]: Andrew Dunkley, thanks for listening into another episode. Don't forget to leave some reviews and

[00:31:18] [SPEAKER_01]: check our social media and our website while you're at it. And we will catch you again soon

[00:31:23] [SPEAKER_01]: on another episode of Space Nuts. Bye-bye. Space Nuts. You've been listening to the Space Nuts

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