Mars Gullies Aren't Made by Water: The Surprising Dry Ice Answer

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Andrew Dunkley: Hello. Thanks for joining us. This is Space

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Nuts. A fresh, crisp episode for you

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to devour, I hope. My name is Andrew Dunkley.

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Uh, your host. Great to have your company.

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Uh, a bit of a water theme in this particular

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episode, or partly.

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There's a question being raised in, uh,

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space science about what causes the

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gullies on Mars. Well, we know that gullies

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are caused by, uh, water flows and rainfall

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on Earth. But, um, that can't be the case on

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Mars. Or can it? They think they've figured

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it out and it's quite a surprising thing.

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Uh, we're also going to look at water on the

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moon, or the lack of which could threaten

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future cities and the search for

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ocean worlds. They think they know how. We'll

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tell you all about it on this episode of

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space nuts.

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Generic: 15 seconds. Guidance is internal.

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10, 9, ignition

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sequence.

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Professor Fred Watson: Star space nuts.

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Generic: 5, 4, 3, 2, 1, 2, 3, 4,

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5, 5, 4, 3, 2', 1.

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Andrew Dunkley: Space nuts.

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Generic: Astronau. But it feels good.

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Andrew Dunkley: To help us with all of that is Professor

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Fred Watson Watson, Astronomer Large,

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sporting his new knee because he

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wanted to be needed.

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Professor Fred Watson: Oh, uh, dear. That's all

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right. Um, that's, uh,

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that's as good as they get today.

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Andrew Dunkley: I think it's, you know, that's. That's dad

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joke. Yeah, that's just beyond

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a dad joke. That's. That's weird.

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Professor Fred Watson: So it was three, three weeks ago yesterday

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that I got my new knee. So progress is

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happening. I am walking pretty well now.

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Um, I have yet to

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have my first drive in the car, but that'll

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be this week, I think. I'm told that I'm

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allowed to do that now. I'm off the

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high, um, intensity medication. Uh,

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and, uh, so far, so good. There was a

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bad week last week when things took a turn

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for the worse, uh, because I had an allergic

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reaction to the dressings that were on the

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knee. That can be

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quite dangerous, it turns out. They didn't

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tell me that until after they'd fixed the

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problem. Um, so, yeah,

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anyway, so it's all good. Everybody's happy

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at the moment.

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Generic: Yeah.

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Andrew Dunkley: Uh, the only downside is you've got the

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hybrid knee, which means every night you've

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got to plug it in to charge it.

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Professor Fred Watson: A bionic knee would be good for that. You

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could perhaps get up to speed a bit faster

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than I do at the moment, but no, it's working

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very well. All credit to the team who did the

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job. Dr. Parker and his friends and

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stuff. Uh, we had a great. We had a great

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time. I.

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Andrew Dunkley: It reminds me of Something my son told me

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about because he's always online looking for

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the next weirdest thing. And he said, um, the

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Chinese, I think the Chinese have invented,

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uh, an exoskeleton that you can

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wear that will walk for you so you

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don't have to make the effort.

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Professor Fred Watson: Yeah, yeah. And run.

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Andrew Dunkley: Oh my goodness.

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Professor Fred Watson: Yeah, they're good.

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Andrew Dunkley: Isn't technology going in strange places,

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directions?

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Professor Fred Watson: That's right, yes.

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Andrew Dunkley: But that, that I think is going to be great

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for people in the future who are um, uh,

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have paralysis problems or.

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Professor Fred Watson: Yeah. Profoundly disabled. That's right.

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Andrew Dunkley: Sort of thing.

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Professor Fred Watson: Mhm.

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Andrew Dunkley: And probably good for rehabilitation. Who

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knows?

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Professor Fred Watson: Maybe. Yeah, maybe.

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Andrew Dunkley: All right, uh, let's uh, talk about these

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storeys that are in the news at the

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moment. And the um, the

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focus is on Mars in terms of uh,

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uh, images of Martian Gul. Now a lot of

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things about Mars are so strikingly similar

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to Earth. The canyons and the, and the

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ocean beds and all that. The only thing

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lacking is well, you know, a breathable

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atmosphere, liquid water on the surface,

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weather, uh, etc. Gravity, um.

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But the question has come up as to what

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causes the gullies on Mars. Now my first

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thought was well hang on a minute, they were

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already there. I mean they happened billions

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of years ago and that was when water was

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liquid on the surface. But they've been

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changing without water.

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So what's going on?

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Professor Fred Watson: Uh, indeed, that is a good

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question. So um, probably you and I spoke

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about um, gullies on Mars a long

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time ago because there was a time when

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uh, it was being suggested that

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some of these gullies were due to

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the fact that on the equator on Mars in the

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Martian summertime you can actually

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get temperatures that are high enough for

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liquid water to exist. And the theory was

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that maybe, you know, there's a permafrost of

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uh, ice that come mid

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summer it melts and you get these water

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flows down slopes which are uh, what cause

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the gullies. Gullies I guess they're, you

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know, they're the beginnings of rivers really

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in a way. They're the sort of

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little gentle impressions

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in a landscape which are made by

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flowing water which always wants to go

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downhill. Uh, and eventually you carve out a

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river valley. Um, but as you say,

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uh, some of the early observations, I think

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with Mars Reconnaissance Orbiter, with Mars

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Express, um, those two

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venerable orbiting uh, spacecraft, it was

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quickly realised that these things change on

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a seasonal basis. And that was why

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uh, the thinking was that maybe there's uh,

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enough water to do it. However, um,

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it turns out that you get these

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gullies in regions of Mars where the

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temperature never gets high enough for liquid

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water to exist on the surface. In other words

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the, you know, the higher latitude regions,

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the regions towards the poles. And so

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what has happened is that a group of

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scientists actually in uh, one of the

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Parisian uh universities in France,

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uh, they've looked at the

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alternatives for water. So ruling out water

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you uh, can do it uh, because there's that

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we know what the temperature is, we know what

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the pressure is, uh, it's just not possible

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for liquid water to exist uh in

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some of these regions. But they did actually

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go even a step further. They

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uh, looked um, uh,

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from the data from Mars Express and Mars

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Reconnaissance Orbiter, they looked at the

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spectrum of some of these

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uh, at melting ice fields where

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you're looking really near the poles, ah of

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Mars where some of these gullies are. And

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they found um, there's

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no signature for water in uh, other words,

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water ice is definitely not

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ah, a player or liquid water is definitely

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not a player, um,

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in this storey. And so the alternative

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which we know is present on Mars and

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we know that at least some of Mars's polar

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ice caps are made of this is

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uh, solid carbon dioxide or

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carbon dioxide generally. We

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on Earth are familiar with solid carbon

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dioxide as dry ice. Uh, uh,

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on Mars it does exist.

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We know there's a frost of dry ice near the

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poles. Uh but because the pressure is

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lower on Mars, um, it's got slightly

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different uh mechanisms of

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behaviour. Uh so uh, it

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is possible for dryas, dry ice and

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Earth just sublimes. It goes straight from a

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solid to a gas. But I think under

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certain conditions on Mars it can be a liquid

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for a short time. So uh,

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what's the storey? These researchers

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uh had two theories uh which

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were to try and explain the origin

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uh of the gullies. Uh

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one is something which is um, a

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geyser, um, mechanism. The idea is

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you've got geysers which we're familiar with

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as jets of hot water uh, coming

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up from uh, underneath the surface of

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Earth being heated by magmatic heat.

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I think both of us, you and I, Andrew, have

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been to the place that gives those things

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their name. Geysir in Iceland

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did visit the guys there.

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Andrew Dunkley: Oh yeah, yeah, yeah. Actually the best one

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I've ever seen was in New Zealand.

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Professor Fred Watson: Yeah, at Rotorua.

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Andrew Dunkley: Wow.

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Professor Fred Watson: Rotorua, that's right, yeah. Uh, so

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anyway, um, we don't call them Rotoruas, we

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call them geysers. That's because of the one

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In Iceland. So what's the theory there?

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The theory is that

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um, you've got basically

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a sheet of, of dry

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ice of solid carbon dioxide that

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forms in the wintertime.

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And as spring comes,

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the heat passing through that sheet of

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dry ice, uh, basically warms up the

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soil underneath and that

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turns some of the ice, this

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carbon dioxide ice, into gaseous carbon

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dioxide. So you've got a buildup of pressure

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underneath the sheet of ice and eventually

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the ice basically ruptures bang and out

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comes this high velocity jet of carbon

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dioxide. Um, and the theory

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is that that takes a lot of soil and

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uh, you know, dust and stuff with it and that

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gives you, gives rise to the gullies. It

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gives you the, basically the

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discoloration that we see in the gullies.

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Uh, and that is a mechanism that

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they looked at. But uh, what

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has caused them to discard that idea

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is that the

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geyser action would appear

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um, around the spring

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equinox on Mars. Ah,

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but you don't see this

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gully activity, these darkenings of the

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gullies until later in

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the year. You don't see them until

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getting on almost for the Martian summer when

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those geysers should have shut down. So

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they ruled that out as the

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origin. Um, and this

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is the uh, start of what they looked at

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instead, which is something

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a bit similar. But rather than an

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sort of explosive process with the carbon

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dioxide sort of, you know, bursting out from

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underneath these sheets of dry ice, uh, what

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you've got is the idea that there are, there

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are small, um,

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there aren't, you know, there might be small

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cracks in the ice but there's nothing big.

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But what happens instead of the gas

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bursting out through a large

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crack in the ice, the gas stays underneath

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the sheet of ice but kind of lubricates

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it, uh, uh, so that you've got

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essentially a floating sheet

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of dry ice and of course gravity takes over

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so it slides down the slope and actually

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can cause the appearance of these

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gullies. Uh, and so uh,

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that's their current favourite theory for

264
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how these gullies uh, form. And their

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modelling shows that in the end what you've

266
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got uh, is exactly what we see in uh the

267
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gullies on Mars. Uh, and they make a comment

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um, that Earth, uh, like features don't

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always require Earth like physics. I think

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that might actually be a comment from

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Universe Today, uh, which is where this

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article comes from.

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An old friend of ours, Univers, uh,

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uh, uh, with Fraser Cain and others,

275
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uh, um, involved with that. So no liquid

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water on Mars. But uh, dry ice gullies

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perhaps?

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Andrew Dunkley: Yeah. I like the way they

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describe it for people like me to get

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into our heads what might be going on.

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They call it the air hockey effect.

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Professor Fred Watson: Yes.

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Generic: Ah.

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Andrew Dunkley: If anyone's ever been to an arcade and played

285
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air hockey, it's um, it's played on a

286
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table with lots of little pinholes in it

287
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blowing air up, uh, which causes a

288
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disc to be able to hover when you hit it. And

289
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that's, that's what they think might be the

290
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effect that's changing and causing the

291
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gullies on Mars. So really fascinating,

292
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really fascinating. Um, the other effect

293
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is um, is comparing a human bodily

294
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function. It's not as big and powerful as a

295
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trumpet, but it could be a silent but deadly.

296
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Professor Fred Watson: I'm going to leave that one completely alone,

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Andrew.

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Andrew Dunkley: Just leave that one hanging in the

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Professor Fred Watson: air Fred Watson, as you would, yes.

300
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I'm afraid we've got a dog that does that.

301
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You don't see that side of Jordy's

302
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personality. Um, but we do.

303
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Andrew Dunkley: Hearing, hearing him's enough.

304
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Professor Fred Watson: Yes it is. Yeah, yeah. Oh, uh,

305
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gosh.

306
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Andrew Dunkley: But uh, no, it's fascinating and if you want

307
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to read about IT, universetoday, uh.com is

308
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the website where you'll find that very

309
00:13:07.420 --> 00:13:10.180
interesting storey. This is Space Nuts with

310
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Andrew Dunkley and Professor Fred Watson

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Watson.

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Generic: 0G and I feel fine.

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Andrew Dunkley: Space Nuts, our uh, next storey takes us from

314
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not water on Mars to a particular

315
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lack of water on the moon. And the reason

316
00:13:26.620 --> 00:13:29.380
they're saying that is because of

317
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um, you know, the potential for people living

318
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long term on the lunar surface.

319
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And up until now they've thought well there's

320
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a ready supply of water, everything will be

321
00:13:38.930 --> 00:13:41.570
fine, we can build a million person

322
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city there and um, yeah, it'll be

323
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great. Uh, now they don't think that's the

324
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case. They don't think there's nearly enough

325
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water to sustain uh, even a small

326
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city on uh, on the moon. So

327
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what's um, what's going on there,

328
00:13:56.650 --> 00:13:58.770
Fred Watson? And there's Earth.

329
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Professor Fred Watson: Yeah, Earth just making a comment there. Um,

330
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so thank you Jordan. Yeah,

331
00:14:06.770 --> 00:14:09.390
uh, very tiring. Yeah. One day

332
00:14:09.390 --> 00:14:11.270
we'll, I hope he'll end up on the moon.

333
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So yes, that we've got. And look the

334
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whole, it's really interesting the extent to

335
00:14:18.750 --> 00:14:20.550
which our explanation, you know, our

336
00:14:20.550 --> 00:14:23.510
exploration of the moon in terms of human

337
00:14:23.510 --> 00:14:26.070
landing is focused on this idea

338
00:14:26.560 --> 00:14:29.560
of there being copious water uh, on the

339
00:14:29.560 --> 00:14:32.160
moon. Uh, I'm doing a talk this weekend

340
00:14:32.320 --> 00:14:34.680
uh, at Macquarie uh, University. I'm their

341
00:14:34.680 --> 00:14:36.920
Keynote speaker for their open astronomy

342
00:14:36.920 --> 00:14:38.800
night, which I'm very honoured to be doing.

343
00:14:39.220 --> 00:14:42.159
Um, and it's. My talk's about the future

344
00:14:42.159 --> 00:14:45.040
of Artemis and uh, other ventures

345
00:14:45.200 --> 00:14:47.840
to the Moon. And it all focuses

346
00:14:48.000 --> 00:14:50.960
on the southern polar region of the Moon

347
00:14:51.120 --> 00:14:51.520
where

348
00:14:53.860 --> 00:14:56.730
uh, there is a cluster

349
00:14:56.810 --> 00:14:59.530
of quite deep craters which

350
00:14:59.690 --> 00:15:02.690
never see sunlight, uh, because they're

351
00:15:02.690 --> 00:15:05.210
at the south pole. Um, the

352
00:15:05.690 --> 00:15:08.620
sun always misses their depths. Uh,

353
00:15:08.620 --> 00:15:11.130
some of them are quite deep. The one

354
00:15:11.290 --> 00:15:13.050
actually at the south pole, which is called

355
00:15:13.050 --> 00:15:15.090
Shackleton Crater, that's four kilometres

356
00:15:15.090 --> 00:15:17.780
deep, it's 20 kilometres across. Um,

357
00:15:17.780 --> 00:15:20.540
and uh, the evidence from previous space

358
00:15:20.540 --> 00:15:23.060
missions is that there is water ice

359
00:15:23.540 --> 00:15:25.500
in the base of these craters that may be

360
00:15:25.500 --> 00:15:27.960
billions of years old. Andrew because, uh,

361
00:15:27.960 --> 00:15:30.700
it's never seen the sun, so it's never been,

362
00:15:30.700 --> 00:15:33.300
you know, warmed up enough to turn into a

363
00:15:33.300 --> 00:15:35.220
gas. And the temperature in some of these

364
00:15:35.220 --> 00:15:37.980
craters is extremely low, um, minus

365
00:15:37.980 --> 00:15:40.660
200 or thereabouts. So it's frozen

366
00:15:40.660 --> 00:15:43.380
solid. So, um, we've got this whole

367
00:15:43.860 --> 00:15:46.460
focus now on getting um,

368
00:15:46.920 --> 00:15:49.720
spacecraft and humans eventually with

369
00:15:49.720 --> 00:15:52.700
Artemis 4, hopefully, uh,

370
00:15:52.700 --> 00:15:55.160
early in 2028, uh, actually

371
00:15:55.560 --> 00:15:58.440
landing on the Moon in this region. Uh, and

372
00:15:58.440 --> 00:16:00.400
it's quite a hazardous thing to do because

373
00:16:00.400 --> 00:16:02.280
the south pole of the Moon is very

374
00:16:02.280 --> 00:16:04.400
mountainous. It's got all these craters. It's

375
00:16:04.400 --> 00:16:07.200
not smooth, uh, sailing in terms of

376
00:16:07.200 --> 00:16:09.720
finding nice, um, flat places to land,

377
00:16:10.120 --> 00:16:12.760
as happened with the Apollo missions, which

378
00:16:12.760 --> 00:16:15.680
were all in much less

379
00:16:15.680 --> 00:16:18.660
challenging parts of the Moon's surf. So the

380
00:16:18.660 --> 00:16:21.060
focus on water on the Moon is

381
00:16:21.060 --> 00:16:23.780
enormous and uh, I don't

382
00:16:23.940 --> 00:16:26.620
know that it's really been

383
00:16:26.620 --> 00:16:29.380
looked at in great detail before,

384
00:16:29.940 --> 00:16:32.580
but we now have some work that

385
00:16:32.580 --> 00:16:35.540
suggests that, uh, yes, there probably

386
00:16:35.540 --> 00:16:38.420
is water on the Moon's surface,

387
00:16:38.900 --> 00:16:41.740
but, uh, there might not

388
00:16:41.740 --> 00:16:43.780
be enough of it to make it,

389
00:16:44.570 --> 00:16:47.470
um, you know, uh, available on an industrial

390
00:16:47.470 --> 00:16:49.470
scale, if I can put that. A place where

391
00:16:49.710 --> 00:16:52.670
humans could survive, uh, permanently or

392
00:16:52.750 --> 00:16:54.830
where you could have permanent presence.

393
00:16:55.630 --> 00:16:58.390
So it's um, a theory

394
00:16:58.390 --> 00:17:01.070
that really I think will start, uh, you know,

395
00:17:01.070 --> 00:17:03.710
raising a few eyebrows.

396
00:17:04.130 --> 00:17:07.070
Um, uh, it's come from,

397
00:17:08.190 --> 00:17:10.990
I guess, um, the idea of

398
00:17:11.590 --> 00:17:14.510
uh, just how much water there

399
00:17:14.510 --> 00:17:17.390
is there, um, you know, on the basis of the

400
00:17:17.390 --> 00:17:19.270
geography, if I can put it that way, the fact

401
00:17:19.270 --> 00:17:21.980
that you have got these deep craters, um,

402
00:17:22.550 --> 00:17:25.430
I, I uh, think the

403
00:17:25.430 --> 00:17:28.280
jury is still out on, on

404
00:17:28.280 --> 00:17:30.990
um, uh, just how much

405
00:17:30.990 --> 00:17:33.670
water there is, what form it takes, because

406
00:17:33.670 --> 00:17:36.150
it, you know, it could be buried under,

407
00:17:36.550 --> 00:17:37.350
under rock.

408
00:17:37.600 --> 00:17:39.990
Uh, we're really in a, in a region

409
00:17:40.310 --> 00:17:42.790
of um, very big unansw

410
00:17:43.970 --> 00:17:46.210
and um, I don't think we've Talked about

411
00:17:46.210 --> 00:17:49.050
this, uh, Andrew, but um, Chang'

412
00:17:49.050 --> 00:17:51.850
E7 which is a Chinese ah, mission

413
00:17:51.850 --> 00:17:54.690
to land, uh, very near Shackleton Crater,

414
00:17:54.690 --> 00:17:56.720
actually the one I've just mentioned, uh,

415
00:17:57.170 --> 00:17:58.930
which was supposed to launch,

416
00:17:59.970 --> 00:18:02.050
actually I think the day before my knee

417
00:18:02.050 --> 00:18:03.730
operation it was supposed to launch but it

418
00:18:03.730 --> 00:18:06.730
was cancelled at very short notice

419
00:18:06.730 --> 00:18:09.330
with a fairly brief note from the China

420
00:18:09.970 --> 00:18:12.790
uh, space Agency, uh,

421
00:18:12.830 --> 00:18:15.590
and uh, that now looks as though it won't

422
00:18:15.590 --> 00:18:18.470
happen till 2027. But that spacecraft

423
00:18:18.470 --> 00:18:21.350
carried uh, not just a rover, there's an

424
00:18:21.350 --> 00:18:24.230
orbiter, a rover and a lander of course, but

425
00:18:24.230 --> 00:18:26.590
also a hopper, a little

426
00:18:26.990 --> 00:18:29.070
vehicle that will hop into

427
00:18:29.470 --> 00:18:32.230
craters rather than try and go down

428
00:18:32.230 --> 00:18:34.910
into craters on wheels. And

429
00:18:35.070 --> 00:18:37.790
that's um, the idea is to use that hopper,

430
00:18:38.090 --> 00:18:40.670
uh, to try and find the water chang' uh e7

431
00:18:41.470 --> 00:18:43.790
when it is launched, might be the first we

432
00:18:43.790 --> 00:18:46.190
know of, uh, you know, first, first hand,

433
00:18:46.860 --> 00:18:49.350
um, experience, if I can put it that way, of

434
00:18:49.350 --> 00:18:51.230
what the water is like in these craters.

435
00:18:51.710 --> 00:18:53.110
Sadly uh, we're going to have to wait a bit

436
00:18:53.110 --> 00:18:56.030
longer than we thought we did. But uh, that's

437
00:18:56.350 --> 00:18:57.389
one step forward.

438
00:18:57.390 --> 00:19:00.110
And the hopper by the way is unlike anything

439
00:19:00.110 --> 00:19:02.670
that NASA is planning for the Artemis

440
00:19:02.670 --> 00:19:05.070
mission. So really interesting area.

441
00:19:05.600 --> 00:19:08.560
Uh, we, I think we're still groping in the

442
00:19:08.560 --> 00:19:10.560
dark a bit, if I can put it that way, given

443
00:19:10.560 --> 00:19:12.880
that these craters are definitely in the dark

444
00:19:13.200 --> 00:19:15.240
about just how much water there is. But it's

445
00:19:15.240 --> 00:19:16.760
possible that there might not be enough to

446
00:19:16.760 --> 00:19:18.480
make it that uh, well worthwhile.

447
00:19:19.120 --> 00:19:21.720
Andrew Dunkley: Yeah, I suppose you've got to consider the

448
00:19:21.720 --> 00:19:24.120
limitations in our capacity to look for it.

449
00:19:24.120 --> 00:19:26.720
At the moment they've only got the

450
00:19:26.880 --> 00:19:29.760
ability to look to shallow depths.

451
00:19:29.760 --> 00:19:32.690
So there could be water uh, deeper in

452
00:19:32.690 --> 00:19:35.050
the Moon's, um. Yes,

453
00:19:35.610 --> 00:19:38.490
yes, that, that we haven't found. So

454
00:19:38.490 --> 00:19:39.610
there may be more.

455
00:19:41.130 --> 00:19:43.290
But based on what we know now,

456
00:19:43.690 --> 00:19:46.370
putting a um, a city on the

457
00:19:46.370 --> 00:19:49.090
moon for you know, hundreds of

458
00:19:49.090 --> 00:19:51.050
thousands of people, it's just not feasible.

459
00:19:51.050 --> 00:19:53.250
It wouldn't uh, it wouldn't last. I think

460
00:19:53.250 --> 00:19:54.570
they said it wouldn't last a year.

461
00:19:55.370 --> 00:19:55.730
Professor Fred Watson: Yeah.

462
00:19:55.730 --> 00:19:58.330
Andrew Dunkley: Based on the resources that exist on current

463
00:19:58.570 --> 00:20:01.390
estimates, I couldn't

464
00:20:01.390 --> 00:20:04.030
imagine that many people living on the Moon,

465
00:20:04.030 --> 00:20:04.470
can you?

466
00:20:05.030 --> 00:20:07.340
Professor Fred Watson: No, not really. Uh, I think um,

467
00:20:08.470 --> 00:20:11.190
it's not a place you'd want to.

468
00:20:11.670 --> 00:20:14.430
I can imagine there being things like the

469
00:20:14.430 --> 00:20:17.030
outpost we have in Antarctica. I think that's

470
00:20:17.670 --> 00:20:20.470
a sort of reasonably sustainable model for

471
00:20:20.790 --> 00:20:23.670
exploring the Moon. But yeah, cities of

472
00:20:24.150 --> 00:20:26.230
tens of thousands of people I think is a non

473
00:20:26.230 --> 00:20:29.030
starter and this perhaps

474
00:20:29.030 --> 00:20:30.950
underlines that. That's, I guess the point

475
00:20:31.200 --> 00:20:31.770
uh, of

476
00:20:31.770 --> 00:20:34.450
Andrew Dunkley: the article, uh, they do

477
00:20:34.530 --> 00:20:37.370
go on to say that, um, a village of a

478
00:20:37.370 --> 00:20:39.210
thousand, maybe ten thousand people would

479
00:20:39.210 --> 00:20:42.170
last centuries though, if they kept

480
00:20:42.170 --> 00:20:44.900
the numbers down. So, um,

481
00:20:45.330 --> 00:20:47.610
the resources that exist at the moment are

482
00:20:47.610 --> 00:20:49.010
feasible to an extent.

483
00:20:49.570 --> 00:20:50.050
Professor Fred Watson: Yes.

484
00:20:51.540 --> 00:20:54.370
Andrew Dunkley: Um, and you

485
00:20:54.370 --> 00:20:56.770
also have to bring into play things

486
00:20:57.090 --> 00:20:59.880
like recycling, uh, of water. Uh, they

487
00:20:59.880 --> 00:21:02.480
use recycled water on the International Space

488
00:21:02.480 --> 00:21:04.600
Station and I think it's got over 98

489
00:21:04.840 --> 00:21:07.440
efficiency. You'd have to do that on the

490
00:21:07.440 --> 00:21:09.720
moon, otherwise you're going to go through it

491
00:21:09.720 --> 00:21:12.200
like a packet of salt and

492
00:21:12.840 --> 00:21:13.400
quite.

493
00:21:14.760 --> 00:21:15.160
Professor Fred Watson: And.

494
00:21:15.400 --> 00:21:17.880
Andrew Dunkley: And then you've got a real problem. The only

495
00:21:17.880 --> 00:21:20.160
other way of dealing with it, well, two ways

496
00:21:20.160 --> 00:21:22.480
would be to transport water from Earth. But

497
00:21:22.480 --> 00:21:25.480
do we really want to do that? Uh, or harvest

498
00:21:25.480 --> 00:21:28.110
it. Harvest it from somewhere else.

499
00:21:28.910 --> 00:21:31.220
Professor Fred Watson: That's the whole point of going to the moon.

500
00:21:31.220 --> 00:21:33.470
Uh, and of course, this water is not just for

501
00:21:33.790 --> 00:21:36.550
keeping a city running, it's to act as rocket

502
00:21:36.550 --> 00:21:39.430
fuel for future, uh, exploration beyond the

503
00:21:39.430 --> 00:21:42.270
moon. So that's one of the appealing features

504
00:21:42.270 --> 00:21:44.750
about it. Yeah, very interesting. Um,

505
00:21:44.990 --> 00:21:47.870
and, uh, it does

506
00:21:48.750 --> 00:21:51.190
beg the question as to whether strategies

507
00:21:51.190 --> 00:21:54.110
will change dramatically, uh, once

508
00:21:54.110 --> 00:21:56.750
we've had a chance to see it firsthand just

509
00:21:56.750 --> 00:21:59.590
how much water there is there. Because

510
00:21:59.670 --> 00:22:00.310
that's still.

511
00:22:00.790 --> 00:22:03.710
Andrew Dunkley: Yeah, it might force Elon to, uh, he's

512
00:22:03.710 --> 00:22:05.430
abandoned Mars already. Too hard.

513
00:22:06.070 --> 00:22:08.990
Um, now that the moon's lacking water, he

514
00:22:08.990 --> 00:22:11.590
might go, well, we won't go there either.

515
00:22:11.590 --> 00:22:13.750
What's Enceladus doing at the moment?

516
00:22:15.350 --> 00:22:16.310
Professor Fred Watson: Yes, that's right.

517
00:22:16.630 --> 00:22:17.070
Andrew Dunkley: Yeah.

518
00:22:17.070 --> 00:22:18.550
Professor Fred Watson: Could be squirting water out.

519
00:22:18.550 --> 00:22:21.240
Andrew Dunkley: Yeah, well, that'd make it easy to

520
00:22:21.240 --> 00:22:23.720
collect. Uh, if you want to read about that,

521
00:22:23.720 --> 00:22:26.720
it's on the Phys P h y s fizz.org website.

522
00:22:26.720 --> 00:22:28.840
Or you can read the study that was published

523
00:22:28.840 --> 00:22:31.280
in Frontiers in Space Technologies.

524
00:22:32.160 --> 00:22:33.720
You're, uh, listening to Space Nuts with

525
00:22:33.720 --> 00:22:35.800
Andrew Dunkley and Professor Fred Watson

526
00:22:35.800 --> 00:22:36.480
Watson.

527
00:22:38.560 --> 00:22:40.560
Generic: I think we need to do a little more all

528
00:22:40.560 --> 00:22:41.520
weather testing.

529
00:22:42.160 --> 00:22:43.840
Professor Fred Watson: Amen, Space Nuts.

530
00:22:44.080 --> 00:22:46.770
Andrew Dunkley: Our final storey. Fred Watson, uh, continues

531
00:22:46.770 --> 00:22:49.610
to look for water, but on a

532
00:22:49.610 --> 00:22:52.450
much larger scale. Uh, we've been looking

533
00:22:52.690 --> 00:22:55.570
for exoplanets for yonks now

534
00:22:55.570 --> 00:22:58.130
and we've found five and a half thousand

535
00:22:58.210 --> 00:23:01.090
plus. But we haven't found a water world,

536
00:23:01.329 --> 00:23:04.130
an ocean world. And they think they

537
00:23:04.130 --> 00:23:07.130
now know how to look for them, I

538
00:23:07.130 --> 00:23:08.530
think is the gist of this storey.

539
00:23:08.610 --> 00:23:10.530
Professor Fred Watson: That's correct. That's right.

540
00:23:11.210 --> 00:23:14.090
Um, yeah. So, yeah, this

541
00:23:14.090 --> 00:23:16.590
is actually a storey I like a lot because I,

542
00:23:16.590 --> 00:23:18.270
um, remember being very excited,

543
00:23:19.110 --> 00:23:22.070
uh, back in the early 2000s,

544
00:23:22.070 --> 00:23:24.710
I guess, uh, when this.

545
00:23:24.710 --> 00:23:27.630
Exactly this same technique, uh, that is

546
00:23:27.630 --> 00:23:30.510
being discussed here was used

547
00:23:30.750 --> 00:23:32.510
to demonstrate that

548
00:23:33.370 --> 00:23:36.270
uh, Saturn's moon Titan has

549
00:23:36.430 --> 00:23:39.230
liquid ocean, not liquid oceans, I beg your

550
00:23:39.230 --> 00:23:41.830
pardon, liquid seas and lakes near its north

551
00:23:41.830 --> 00:23:44.690
pole. Uh, and it was uh,

552
00:23:44.690 --> 00:23:47.570
images made by the Cassini spacecraft

553
00:23:47.890 --> 00:23:50.610
in its early period of uh, orbiting

554
00:23:50.610 --> 00:23:53.610
around Saturn. The problem with Titan

555
00:23:53.610 --> 00:23:56.550
is it's got a thick atmosphere, uh,

556
00:23:56.550 --> 00:23:59.490
that is almost completely opaque. And

557
00:23:59.490 --> 00:24:02.370
so uh, you can use infrared to penetrate

558
00:24:02.370 --> 00:24:04.970
through it for a while, but uh,

559
00:24:06.610 --> 00:24:08.130
to some depth of clarity.

560
00:24:08.530 --> 00:24:10.070
But um,

561
00:24:12.660 --> 00:24:15.660
the real way of exploring uh, Titan, which

562
00:24:15.660 --> 00:24:18.420
is what Cassini did, is by radar,

563
00:24:18.430 --> 00:24:21.060
uh, you do it by radar. And that's

564
00:24:21.490 --> 00:24:23.980
uh, one of the reasons that we've been able

565
00:24:23.980 --> 00:24:26.740
to map uh, these seas and lakes.

566
00:24:26.900 --> 00:24:29.700
But the way they were first detected was

567
00:24:29.860 --> 00:24:32.540
when Cassini, uh, when its

568
00:24:32.540 --> 00:24:35.140
cameras were aimed at Titan,

569
00:24:35.990 --> 00:24:38.890
Uh, uh, at a time when

570
00:24:39.210 --> 00:24:41.770
the angle between the

571
00:24:41.770 --> 00:24:44.650
spacecraft, the moon,

572
00:24:44.650 --> 00:24:46.970
Titan itself and the sun

573
00:24:47.370 --> 00:24:49.530
was such that you would get a direct

574
00:24:49.610 --> 00:24:52.210
reflection off the liquid

575
00:24:52.210 --> 00:24:54.570
surface that was thought to be near the north

576
00:24:54.570 --> 00:24:57.050
pole of Titan. And sure enough,

577
00:24:57.750 --> 00:25:00.330
uh, there was uh, what we call a glint,

578
00:25:00.790 --> 00:25:03.530
uh, which is a sun glint comes from a

579
00:25:03.530 --> 00:25:05.850
liquid water surface that was detected.

580
00:25:06.330 --> 00:25:08.630
That's how Cassini, Cassini first established

581
00:25:08.950 --> 00:25:11.250
that there are lakes and seas, uh,

582
00:25:11.870 --> 00:25:14.430
uh, on Titan. And it was then they were

583
00:25:14.430 --> 00:25:17.230
subsequently mapped uh, very accurately

584
00:25:17.230 --> 00:25:20.190
by uh, Cassini's radar. I've still

585
00:25:20.190 --> 00:25:22.150
got some extraordinary maps that came from

586
00:25:22.230 --> 00:25:25.030
that era showing uh, these seas and

587
00:25:25.030 --> 00:25:27.910
lakes um, near Titan's north pole. So

588
00:25:28.070 --> 00:25:30.310
the question that is being asked in this

589
00:25:30.310 --> 00:25:32.030
piece of research that we're talking about

590
00:25:32.030 --> 00:25:33.710
once again this comes to us courtesy of

591
00:25:33.710 --> 00:25:35.750
Universe today, uh, is

592
00:25:36.990 --> 00:25:39.150
can you do the same thing with

593
00:25:39.470 --> 00:25:41.390
exoplanets? Supposing you

594
00:25:42.750 --> 00:25:45.460
have uh, a suspicion that uh,

595
00:25:45.550 --> 00:25:48.110
One of the 5,500

596
00:25:48.510 --> 00:25:51.310
now known exoplanets, planets orbiting

597
00:25:51.740 --> 00:25:54.710
uh, other stars, if you have a suspicion that

598
00:25:54.710 --> 00:25:56.630
one of them might have conditions where

599
00:25:56.630 --> 00:25:59.630
liquid water could exist, or in the case

600
00:25:59.630 --> 00:26:01.790
of, as in the case of Titan, liquid

601
00:26:01.790 --> 00:26:04.350
hydrocarbons, liquid natural gas.

602
00:26:04.830 --> 00:26:07.250
Um, could you use this glint technique

603
00:26:07.750 --> 00:26:10.640
uh, to try and establish if you

604
00:26:10.640 --> 00:26:13.400
did have a ah, water world, in other words

605
00:26:14.120 --> 00:26:16.680
a world covered completely by oceans.

606
00:26:17.250 --> 00:26:20.040
Uh, and those things have been hypothesised,

607
00:26:20.040 --> 00:26:21.440
actually we've talked about them before,

608
00:26:21.440 --> 00:26:24.090
these so called Hycean worlds. Uh,

609
00:26:24.090 --> 00:26:27.000
Hycean is basically a

610
00:26:27.000 --> 00:26:29.800
term that's been uh, concocted to represent

611
00:26:29.880 --> 00:26:31.880
a world with an atmosphere of hydrogen.

612
00:26:31.880 --> 00:26:34.080
That's where the high comes from. Uh, but a

613
00:26:34.080 --> 00:26:37.070
liquid ocean surface, uh, hence the shen.

614
00:26:37.310 --> 00:26:40.150
So it's a Haitian world. How could you use

615
00:26:40.150 --> 00:26:43.070
this glint technique to demonstrate

616
00:26:43.230 --> 00:26:46.190
that a suspected Haitian world really

617
00:26:46.190 --> 00:26:48.590
was a Haitian world? So two

618
00:26:48.590 --> 00:26:51.110
scientists at the University of

619
00:26:51.110 --> 00:26:54.110
Arizona, uh, which is in Tucson, Uh, I've got

620
00:26:54.110 --> 00:26:56.550
some good friends there, but they don't

621
00:26:56.550 --> 00:26:58.430
include these people. I don't know them well

622
00:26:58.670 --> 00:27:01.310
or all I know is their names. Uh, what

623
00:27:01.310 --> 00:27:03.400
they've done is they've, they've

624
00:27:03.960 --> 00:27:06.280
done what you might call the physics of how

625
00:27:06.280 --> 00:27:08.840
glints might work. Uh, and

626
00:27:12.360 --> 00:27:15.240
the bottom line is that

627
00:27:15.800 --> 00:27:18.519
it's potentially a good

628
00:27:18.519 --> 00:27:21.240
way of doing this. But there are certain

629
00:27:21.320 --> 00:27:23.640
conditions that have to be

630
00:27:23.800 --> 00:27:25.960
fulfilled, um, because

631
00:27:26.600 --> 00:27:29.120
you've got to get the angles right first of

632
00:27:29.120 --> 00:27:31.640
all. Um, and, and that

633
00:27:31.640 --> 00:27:33.960
angle is all about

634
00:27:35.560 --> 00:27:38.480
the object being relatively near to

635
00:27:38.480 --> 00:27:41.160
its parent star. So you get this

636
00:27:41.290 --> 00:27:44.040
um, sort of grazing angle almost

637
00:27:44.040 --> 00:27:46.920
of the water, sorry, the light hitting the

638
00:27:46.920 --> 00:27:49.240
water and then being reflected back. Now that

639
00:27:49.240 --> 00:27:51.480
itself presents a problem because,

640
00:27:51.770 --> 00:27:54.640
um, at the moment most

641
00:27:54.640 --> 00:27:56.600
of the exoplanets that have been discovered

642
00:27:57.070 --> 00:27:59.890
uh, are ah, only known because they

643
00:28:00.250 --> 00:28:02.810
uh, have an effect on their parent star.

644
00:28:02.810 --> 00:28:04.410
Whether it's blocking the light of the parent

645
00:28:04.410 --> 00:28:06.330
star as they pass in front of it or whether

646
00:28:06.330 --> 00:28:09.010
it's pulling it slightly out of position by

647
00:28:09.010 --> 00:28:11.030
what we call the Doppler wobble, um,

648
00:28:11.030 --> 00:28:14.009
technique. Uh, these mean that you

649
00:28:14.009 --> 00:28:15.890
never see the planet that you're trying to

650
00:28:15.890 --> 00:28:17.730
observe. You just see its effect on the star.

651
00:28:18.050 --> 00:28:20.050
So really what we're talking about here could

652
00:28:20.050 --> 00:28:22.210
only apply if you've got direct

653
00:28:22.690 --> 00:28:25.610
observations of the planet. And if you

654
00:28:25.610 --> 00:28:27.610
need the planet to be close to the star to

655
00:28:27.610 --> 00:28:29.640
get the angle right, then that's a chance

656
00:28:30.430 --> 00:28:33.190
because the star is um, sometimes billions of

657
00:28:33.190 --> 00:28:34.830
times brighter than the planet that you're

658
00:28:34.830 --> 00:28:37.710
looking for. However, it's not impossible.

659
00:28:37.790 --> 00:28:39.830
And there are things called coronagraphs,

660
00:28:39.830 --> 00:28:42.510
which are essentially uh, devices that

661
00:28:42.510 --> 00:28:44.510
suppress the light of a star so that you can

662
00:28:44.590 --> 00:28:47.430
look for planets uh, nearby. And

663
00:28:47.430 --> 00:28:49.870
so, uh, what um, these

664
00:28:49.870 --> 00:28:52.550
scientists are doing is feeding this

665
00:28:52.550 --> 00:28:55.470
information into people who are working

666
00:28:56.250 --> 00:28:58.700
on uh, something that I think is still a, ah,

667
00:28:58.730 --> 00:29:01.690
hypothetical spacecraft, uh, something

668
00:29:01.690 --> 00:29:04.010
called the Habitable Worlds Observatory,

669
00:29:04.620 --> 00:29:07.410
uh, which will look at the possibility of

670
00:29:07.410 --> 00:29:09.290
there being habitable worlds among some of

671
00:29:09.290 --> 00:29:11.850
these, uh, five and a half thousand

672
00:29:12.330 --> 00:29:14.770
known exoplanets. Uh, what they've done is

673
00:29:14.770 --> 00:29:17.690
they've fed uh, these conditions,

674
00:29:17.690 --> 00:29:20.490
this information into the designers to

675
00:29:20.490 --> 00:29:22.290
say, yeah, you can probably do this, but you

676
00:29:22.290 --> 00:29:24.370
need to do this, this, this and this when you

677
00:29:24.370 --> 00:29:27.320
build your spacecraft in order for uh,

678
00:29:27.460 --> 00:29:29.620
potential water worlds to be discovered. So

679
00:29:29.620 --> 00:29:30.820
quite a nice piece of research.

680
00:29:31.460 --> 00:29:33.940
Andrew Dunkley: Yes, indeed. I hope they do find something

681
00:29:33.940 --> 00:29:36.100
like that eventually. I think it'd be really

682
00:29:36.100 --> 00:29:38.340
exciting to find a water world,

683
00:29:38.860 --> 00:29:40.900
ah, ice moons, I suppose count

684
00:29:41.540 --> 00:29:44.420
because, um, they have

685
00:29:45.220 --> 00:29:48.060
oceans inside them, but, um.

686
00:29:48.060 --> 00:29:48.580
Professor Fred Watson: Correct.

687
00:29:49.380 --> 00:29:52.260
Andrew Dunkley: An actual planet that is

688
00:29:52.260 --> 00:29:55.100
covered in water. Um, we know of

689
00:29:55.100 --> 00:29:56.820
only one. But

690
00:29:58.500 --> 00:30:01.260
there's got to be more, surely. There's got

691
00:30:01.260 --> 00:30:03.860
to be more. Statistically,

692
00:30:04.180 --> 00:30:05.380
there's got to be more.

693
00:30:06.020 --> 00:30:08.420
Professor Fred Watson: Yeah, one would think that's right. Whether

694
00:30:08.420 --> 00:30:10.740
they are findable by our current technology

695
00:30:11.220 --> 00:30:12.740
is of course, another question.

696
00:30:13.140 --> 00:30:15.860
Andrew Dunkley: Yeah, well, um, in time, maybe.

697
00:30:16.020 --> 00:30:18.740
But then the Vera Rubin Observatory,

698
00:30:19.240 --> 00:30:22.040
who knows, um, that

699
00:30:22.120 --> 00:30:23.560
we'd never even thought of.

700
00:30:24.280 --> 00:30:26.320
Professor Fred Watson: That's correct. And of course an anti Grace

701
00:30:26.320 --> 00:30:29.080
Roman, uh, spacecraft recently launched,

702
00:30:29.080 --> 00:30:30.800
which we hope we'll see results from early

703
00:30:30.800 --> 00:30:33.350
next year, that does have a coronagraph. Uh,

704
00:30:33.350 --> 00:30:36.240
so it does have a device to look at some of

705
00:30:36.240 --> 00:30:38.280
these planets directly.

706
00:30:38.760 --> 00:30:41.560
Andrew Dunkley: Yes, indeed. Uh, very exciting times ahead

707
00:30:42.120 --> 00:30:44.360
and, um, won't be long before we start

708
00:30:44.360 --> 00:30:47.260
getting, um, some information back from,

709
00:30:47.650 --> 00:30:50.020
uh, that telescope either. Uh, it's on its

710
00:30:50.020 --> 00:30:52.820
way. Uh, yes. Uh, so if you'd like to read

711
00:30:52.820 --> 00:30:54.740
about that particular storey in the search

712
00:30:54.740 --> 00:30:57.660
for water Worlds UniverseToday, uh, dot com

713
00:30:57.900 --> 00:31:00.780
again is, uh, is a source that's, uh, very

714
00:31:00.859 --> 00:31:02.140
well worth visiting.

715
00:31:02.860 --> 00:31:05.140
And that brings us to the end of the show.

716
00:31:05.140 --> 00:31:06.380
Fred Watson, thank you so much.

717
00:31:07.900 --> 00:31:10.060
Professor Fred Watson: You're welcome, Andrew. Um, it's been a

718
00:31:10.060 --> 00:31:11.860
pleasure and a privilege to talk to you and

719
00:31:11.860 --> 00:31:13.890
I. I do hope we can do it again sometime.

720
00:31:13.890 --> 00:31:16.490
Andrew Dunkley: I, I hope we can do it really, really,

721
00:31:16.490 --> 00:31:17.490
really, really soon.

722
00:31:19.250 --> 00:31:20.050
Professor Fred Watson: Maybe so.

723
00:31:20.530 --> 00:31:22.490
Andrew Dunkley: Catch you soon, professor, uh, Fred Watson

724
00:31:22.490 --> 00:31:24.850
Watson, astronomer at large. And while you're

725
00:31:24.850 --> 00:31:27.090
waiting for a new episode, um, please visit

726
00:31:27.090 --> 00:31:29.450
our website. Uh, you can send us a message as

727
00:31:29.450 --> 00:31:32.010
you, um, as you like. Uh, we've had a couple

728
00:31:32.010 --> 00:31:34.570
of messages um, from our live audience this

729
00:31:34.570 --> 00:31:37.370
morning. Hello to Al in Old South

730
00:31:37.370 --> 00:31:39.460
Wales. He said, uh, he's just about to go to

731
00:31:39.460 --> 00:31:41.940
bed. And, uh, one from

732
00:31:41.940 --> 00:31:44.570
Halil. I hope I got that right. Who's been,

733
00:31:44.570 --> 00:31:47.430
uh, inspired to, um,

734
00:31:47.820 --> 00:31:50.620
venture, uh, out with his studies in computer

735
00:31:50.620 --> 00:31:52.500
engineering, uh, because he listens to Space

736
00:31:52.500 --> 00:31:54.220
nuts. So thanks for that message, that's

737
00:31:54.220 --> 00:31:56.580
lovely. Uh, but, yeah, our website,

738
00:31:56.580 --> 00:31:59.180
spacenutspodcast.com or spacenuts

739
00:31:59.580 --> 00:32:02.060
IO where you can send us messages. You can,

740
00:32:02.130 --> 00:32:04.530
um, do, uh, that through the AMA link and,

741
00:32:04.680 --> 00:32:06.520
and all sorts of other things. Uh, visit the

742
00:32:06.520 --> 00:32:07.880
shop while you're there. Some new books in

743
00:32:07.880 --> 00:32:08.360
the shop.

744
00:32:09.320 --> 00:32:12.200
Yeah. Uh, and plenty of other things

745
00:32:12.200 --> 00:32:14.840
to do. And thanks to Huw in the studio.

746
00:32:15.480 --> 00:32:18.200
Couldn't, um, be with us today. Uh, we were

747
00:32:18.200 --> 00:32:20.440
talking about sun glints. Well, uh, Huw did a

748
00:32:20.440 --> 00:32:22.320
bit of a flashing of his own, so I've got to

749
00:32:22.320 --> 00:32:24.560
go down and bail him out after this. And from

750
00:32:24.560 --> 00:32:26.360
me, Andrew Dunkley thanks for your company.

751
00:32:26.440 --> 00:32:28.520
We'll catch you on the next episode of Space

752
00:32:28.520 --> 00:32:31.400
Nuts. Bye bye, Space Nuts. You've been

753
00:32:31.400 --> 00:32:33.590
listening to the Space Podcast,

754
00:32:35.190 --> 00:32:37.910
available at Apple Podcasts, Spotify,

755
00:32:38.070 --> 00:32:40.870
iHeartRadio or your favourite podcast

756
00:32:40.870 --> 00:32:41.190
player.

757
00:32:41.270 --> 00:32:43.910
You can also stream on demand at bytes.

758
00:32:43.910 --> 00:32:46.710
Professor Fred Watson: Com. This has been another quality podcast

759
00:32:46.710 --> 00:32:48.310
production from Bytes.

760
00:32:48.390 --> 00:32:48.550
Generic: Com. Um.