Mars' Hidden Oceans, Sweat Shields & The Universe's Sudden End

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Andrew Dunkley: Hi there. This is Space Nuts, where we talk astronomy

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and space science. And my name is Andrew Dunkley, your host.

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It's good to have your company on this episode.

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We're going to Mars, uh, where we're going to

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talk about water. Now, water is a very common

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Martian topic, uh, but

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this story is going to throw a completely

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different light on Mars water. And we'll

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tell you why. Uh, there's also a

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great idea that's being put forward to

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help spacecraft, uh, re enter

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Earth's atmosphere. Because up until now, we've used heat

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shields and tiles. Now they think

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they've come up with something completely different. It's called

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Sweat and the

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Universe RIP Yep,

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we're going to see it all end much sooner than we

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expected. We'll talk about all of that on this episode

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of space nuts.

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Generic: 15 seconds. Guidance is internal.

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10, 9. Uh, ignition

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sequence start. Uh, space nuts. 4, 3.

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

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Uh, 4, 3, 2, 1. Space nuts. Astronauts

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report it feels good.

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Andrew Dunkley: And he's back again.

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For more it is Professor Fred Watson Watson, astronomer at

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large. Hello, Fred Watson.

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Professor Fred Watson: Uh, Andrew. How are you doing?

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Andrew Dunkley: I'm doing quite well, thank you very much. Are you.

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Professor Fred Watson: What a surprise to see it. Yeah, I'm very well, thank you. Yeah.

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Andrew Dunkley: Oh, it is a surprise to see you there. I mean,

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do you like my new background? I'm going to change the background every week

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on my studio.

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Professor Fred Watson: I think that's a good idea. Uh, and, um, I do like

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it. Uh, it's a, uh, place that's close

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to my heart as well as yours. It's a great place.

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Andrew Dunkley: Well, isn't that the saying, I left

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my heart in San Francisco.

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Professor Fred Watson: Yeah, you probably did.

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Andrew Dunkley: That's a photo I took after we crossed the

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Golden Gate Bridge looking back to San Francisco. So

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thought I'd use that as my backdrop today.

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Professor Fred Watson: The, um, second line of that song is a good one as well.

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I left my knees in old Peru.

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Courtesy of the goons.

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Andrew Dunkley: Yes, of course. Yeah. Beautiful

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city. Really beautiful city. I think I told you about

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the driverless taxis they've got. But there's so much more

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going for it. Those cable, uh, cars are

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fantastic. Um, we

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obviously did the tourist thing and did a ride on one of those

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and then, you know, did the walk down Lombard

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street, that, uh, zigzaggy street that, um,

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has become quite famous. And I don't know how many movies

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and TV shows it's been in, but, um.

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And it's like all of these things that when you see them on

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tv, you think, oh, wow, got to go see that. And then you get

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there and go, oh, it's. It's a lot smaller than

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I thought. Ah.

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But yeah, um, I don't know what the price of a

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house is on Lombard street, but it's, uh, beautiful homes

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there.

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Professor Fred Watson: Yes.

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Andrew Dunkley: But overall, a beautiful city. Beautiful city. I'd go back

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there tomorrow. Uh, we better get into it,

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Fred Watson.

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And our first topic, uh, today

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is the water on Mars. Or in this

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case, according to a new theory inside

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Mars. And we're talking about massive

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amounts of water.

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Professor Fred Watson: Indeed. That's right, we are. It's not just a

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few drips or drops. Uh, so the

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story, uh, the star of the story, Andrew,

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is NASA's InSight spacecraft,

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which it's almost. It's more

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than a decade ago now. I think that, uh, Insight landed, uh,

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you might remember it landed in the Arctic region,

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region of Mars. And, um, basically

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did one summer's worth of work.

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Because we knew that once it got into winter on

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Mars, the spacecraft would freeze and all the electronics

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would die and it would pass away, which it did.

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Uh, it's still there, of course, but it's inactive. Um,

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so a great, uh, mission,

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uh, it had one little, um,

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hiccup in that the thermometer that they were trying to dig into the

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ground didn't get dug in. You might remember we covered that on

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Spacenauts. But what worked a treat was the

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seismometer. Because it had a

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very sensitive seismometer able, uh,

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to listen to Marsquakes.

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Uh, and, um, Marsquakes are caused by

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a number of things. Um, impacting,

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uh, meteorites actually cause a little

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quake. And they also think there's some

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residual. Not exactly plate tectonics,

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but just slips and slides of fault lines and things of that

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sort, which also create seismic M data.

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Yeah. And so this is

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where the story really starts. Because,

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um, we know, uh, from other evidence

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that Mars, uh, Probably

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between about 4.1 and 3 billion years

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ago, was warm and wet. Uh, the

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evidence is in your face in many ways. You can see

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evidence of beaches and river channels. And,

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you know, the northern hemisphere of Mars is much smoother

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and flatter than the southern hemisphere, which we think is because

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there was possibly an ocean there. So all the evidence, science, uh,

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is that during that early period in Mars's

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history. And just remember that all the planets are

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4.6 billion years old or thereabouts.

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4.7, something like that. 4, uh.1

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billion years is only half a billion years after the

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origin of Mars. But, uh, we think that that

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was more or less the start of when it was a warm and wet

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world and that lasted for nearly a billion years. A little bit more

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perhaps. So um, the

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atmosphere, uh, uh sorry the water on

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Mars is now no longer on the surface.

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And uh, that's pretty evident because it's

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as dry as dust and in fact it's got humidity effectively

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not quite but effectively of zero. Very, very low

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humidity. Um so the questions have

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always been where did the surface water go? We

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know that uh because Mars does not have

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a strong magnetic field it's bombarded intensely

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by the solar wind, uh and that

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tends to separate any water

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uh, vapour uh into its component

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atoms, hydrogen and oxygen and they

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then basically waft off into space. And we know that's happening

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because there's uh, a spacecraft called Marvin or Maven,

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uh which is still active in uh, orbit around Mars and that can

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see this stuff all leaking away. So we

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know that was part of the story. But um, the

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planetary scientists who look at Mars in detail say that's

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not enough. We can't actually account for,

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for all the water that must have been there by

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it just disappearing into space. Um,

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we know some of it's frozen in the polar caps uh

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of Mars. Um, and

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probably you know, hydrolyzed minerals.

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There have been minerals on Mars surface have been

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affected by water. Uh that's still

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the case however uh, there must

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be more. And there was a calculation

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done um, I think by the research group

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that's uh, done this work with the Insights, um,

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lander which estimates that

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the water that's gone missing was uh,

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enough to cover the planet in an

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Ocean between 700 and 900

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metres deep.

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Andrew Dunkley: So that just blowed me away.

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Professor Fred Watson: Yeah, uh,

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it's gone um, where. And that's not an

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insignificant amount of water. Remember Mars is only half the

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diameter of Earth so it's not like uh, an

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earthly amount but it's a lot of water, 700 to

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900 metres deep across the whole planet.

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So uh, where's it gone? Uh

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and you know, if we can find it,

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what, what might it be like? So uh, now

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enter uh insight. Uh

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and actually I was wrong. It's not a decade ago. It was

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2018 when Insight landed uh and

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uh, did all that super work with its sensitive

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seismometer. Uh these

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scientists looked at the

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vibrations that come from

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um, any sort of marsquake caused

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by as I mentioned before, either

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slippage in the rock or uh, a meteorite.

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Uh but you can look very accurately at ah,

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the um, essentially the types of

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waves that you're getting because, uh,

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there are pressure waves and shear waves. I think they're called S waves and

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P waves in the, um. Uh, in the

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jargon of seismometry. But these

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waves, seismographic waves,

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tell you something about the material that they are

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passing through. And that is where

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this, uh, story has gone. Because these

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scientists estimate, uh, what they

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call a significant underground anomaly

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exists, uh, in a layer between

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five and a half and eight kilometres

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below the surface. Because they find that these

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shear waves move more slowly, uh, in that

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region. And the most likely

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explanation. And remember, that's. That's a layer

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that's, you know, it's two and a half kilometres,

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two and a half kilometres thick. Um,

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that layer they think is

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likely to be porous rock,

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uh, like we've got here on planet Earth,

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uh, filled with liquid water, just a little bit like the

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aquifers. And we've got a great one here in Australia, the

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great Artesian Basin, uh, which is.

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Andrew Dunkley: I'm sitting on it, right?

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Professor Fred Watson: You're sitting on it. That's right. You are. Are your feet wet, Andrew,

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or.

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Andrew Dunkley: No, no. We do have, as

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you know, several bores all over the city here

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because, uh, we can tap the Great

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Artesian basin and, and get that water for

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domestic use. So we. We kind of,

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um, take water from that source as well as from

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river. The river is fed by a huge dam

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upstream which is bigger than Sydney Harbour.

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Professor Fred Watson: Uh.

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Andrew Dunkley: And. Yes, that's right, Farendom Dam. So, uh,

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yeah, we, uh, definitely use

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the aquifer water from the great artesian

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basin to supplement the city supply.

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We are actually drought proof. As a consequence of that, we

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will never run out of water because

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we sit on the Great Artesian basin, which

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basically stretches north to south across the entire

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continent down, um, this sort of central, um,

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eastern section.

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Professor Fred Watson: That's correct, yeah.

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Andrew Dunkley: Yeah. It's massive.

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Professor Fred Watson: It is massive.

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Andrew Dunkley: It's like an underground ocean, basically. And that's what we're talking about

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with Mars.

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Professor Fred Watson: That's exactly right. And so it's a really nice,

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um, you know, connection that we have here in Eastern Australia

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with Mars. Uh, this sort of, you

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know, um. It's almost. The rock itself is

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sponge, like in the sense that it holds the water, the

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liquid water.

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And the thinking is, uh, that because

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it's at a depth, as I said, a

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few kilometres, between five and a half and eight kilometres,

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um, the temperature there is warmer than

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it is on the surface by quite a long way because of just the

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internal heat of the planet. Uh, and so they think

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it is actually liquid, uh, and that fits

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the bill in terms of the seismic

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waves that they've detected, uh, that you've actually

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got this liquid water in porous

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rock. Um, and what's

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really nice about this story is, uh, that

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if that is, um, a global,

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uh, layer of rock, and it may well be,

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um, they calculate how much water

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is in it, uh, and sure enough,

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it's enough to cover Mars in a global

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ocean between. Well, the figures they quote is between

253
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520 and 780 metres deep.

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Just about the same as what they think is the missing

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water mass on Mars.

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Andrew Dunkley: So this is sense. Yeah, I mean, this

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is still a maybe, not a definite,

258
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but the numbers certainly support it.

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That's what's really interesting about this story.

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Excuse me. And, uh,

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yeah, the question is, if we go to Mars,

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and I know you don't like

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this, but they will probably establish colonies there. If

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one man has his way, um, will

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they be able to access it? Could it. Could it

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actually hold microbial life and could

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you drink it?

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Professor Fred Watson: Uh, yes, that's right. I mean, the middle question there,

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the. The fact that there might be life in it, that's the one

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that's so intriguing. Uh, I think, I

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suspect at that depth you'd struggle to get

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it. But we do know. And again, this comes from Insight.

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Um. Uh, no, it wasn't. Insight was. It

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was Phoenix. Yes, Phoenix was a spacecraft

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like Insight, uh, which was

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actually, uh, the one that was in the Arctic. And so. I beg your pardon,

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I said something incorrect before. The INSIGHT was in the

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Arctic. Martian Arctic. But it wasn't. It was Phoenix 2

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spacecraft which was very similar. Uh, one was for

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seismometry. INSIGHT was basically giving

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us sight of the inside of Mars and M.

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Phoenix was all about, uh,

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basically, um, sampling the surface rock.

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Uh, and, um, we remember

285
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those classic pictures, they scraped away the top layer.

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Andrew Dunkley: Of soil and there was ice.

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Professor Fred Watson: There's ice underneath it.

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Andrew Dunkley: Yeah, yeah, yeah. Um,

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it was like a kid had been up there with his

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Tonka tractor and he scraped the top of

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the dirt and turned white.

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Professor Fred Watson: That's right. So, uh, that is in the Arctic

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region, but that's telling you there's a permafrost of water

294
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and there is a huge amount there as

295
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well. Uh, but, you know, to find liquid water

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now, um, whether that's drinkable,

297
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probably if you purify it, might have minerals in it that you'd like to

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get rid of. But, uh, I think it will be drinkable.

299
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Um, but yes, the intriguing thing is, as you said, is

300
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whether it could harbour Martian

301
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Biology that's uh, really, really interesting.

302
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Uh, and, and in that regard, um, you

303
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know we've talked about the planetary protection rules before

304
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and uh, um, how

305
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much of spacecraft has to be sterilised before it's sent to

306
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Mars. If it's going anywhere where liquid water could exist,

307
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what it would do. This would mean that we would have to be doubly

308
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careful sort of no matter where you're going on

309
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Mars because deep under the surface there might well be Martian

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microbes that wouldn't like earthly microbes if they

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found their way down through the rocks, so. Oh, uh, absolutely.

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Andrew Dunkley: And, and we've got evidence on Earth of that kind of

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contamination when like the Spanish went to South

314
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America and the South American people

315
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um, were exposed to diseases

316
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that just didn't exist in there.

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Professor Fred Watson: Wipe them out.

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Andrew Dunkley: Wipe them out.

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Professor Fred Watson: Almost completely similar things happened in our own

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country. Andrew as well.

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Andrew Dunkley: Yep, absolutely.

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Professor Fred Watson: Smallpox and things like that. And I should just talking about our country,

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I should mention that some of this work has been carried out by

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Australian investigators at the Australian National University

325
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as well as um, uh, scientists at the Chinese

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Academy of Sciences.

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Andrew Dunkley: Well hopefully there'll be some follow up to um,

328
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maybe confirm what they think.

329
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As I said, the numbers are stacking up in that favour

330
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and it will mean that if uh, that's true,

331
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um, Mars is not a dry

332
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dead planet. It's probably a water world, but a

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different kind of water. And we're seeing more and more

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of that throughout the solar system.

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Professor Fred Watson: We are indeed. That's right.

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Andrew Dunkley: Very exciting indeed. All right, if you'd like to read up on that

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you can uh, see that@the

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conversation.com website. This is

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Space Nuts Andrew Dunkley with Professor Fred Watson

340
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Watson.

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Space Nuts.

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Professor Fred Watson: Speaking of water.

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Andrew Dunkley: Well not quite but uh, we,

344
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we've seen over the

345
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entire space ah, race to

346
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date, um, which began way back in the middle

347
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of the last century, uh, that if you wanted to get a

348
00:16:04.440 --> 00:16:07.240
spacecraft back into the atmosphere

349
00:16:07.240 --> 00:16:10.160
you had to be prepared for it to potentially

350
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burn up uh, unless you put a heat shield on

351
00:16:12.920 --> 00:16:15.180
it. And later those heat uh,

352
00:16:15.400 --> 00:16:18.360
absorbent tiles that were made famous by the

353
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space shuttle and my son has actually got one of those

354
00:16:21.120 --> 00:16:23.960
tiles at his place because he got it as a

355
00:16:23.960 --> 00:16:26.760
secret Santa through um, one of the uh, social media

356
00:16:26.760 --> 00:16:29.600
websites when they used to do that um, and

357
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the warning came do not lick the tile. Well apparently it's

358
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very toxic. Um, so

359
00:16:35.620 --> 00:16:38.540
um, that's how it's been done to date. But now

360
00:16:38.540 --> 00:16:40.380
they've come up with a new idea

361
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that basically involves spacecraft

362
00:16:44.300 --> 00:16:47.020
sweating to Stay cool as they come back

363
00:16:47.020 --> 00:16:49.820
into the atmosphere. This is really fascinating.

364
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Professor Fred Watson: Uh, it's extraordinary. Yeah. And what you've said

365
00:16:53.940 --> 00:16:56.060
is absolutely right. Um,

366
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uh, the traditional uh, heat shield

367
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is called an ablative shield because it ablates the

368
00:17:02.740 --> 00:17:05.720
heat, takes it away. Uh, and that means

369
00:17:06.280 --> 00:17:09.040
that you only use them once. So um,

370
00:17:09.400 --> 00:17:12.320
that's an issue for example with the Orion

371
00:17:12.320 --> 00:17:15.160
capsule which is um, going to be reused. Uh, this

372
00:17:15.160 --> 00:17:17.400
is the one that will take astronauts to the moon.

373
00:17:17.850 --> 00:17:20.840
Um, uh, and um, it's a pretty

374
00:17:20.840 --> 00:17:23.760
large piece of kit and every time you reuse it

375
00:17:23.760 --> 00:17:26.360
you've got to replace that ablative shield that's on there. Or

376
00:17:26.360 --> 00:17:29.320
ablative shield, however you pronounce it. It's on the back of

377
00:17:29.320 --> 00:17:32.320
the spacecraft. That's the bit that burns away, uh, as the

378
00:17:32.320 --> 00:17:35.310
spacecraft re enters. Uh, so, um,

379
00:17:35.310 --> 00:17:37.780
could you find a way of doing this, uh,

380
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which was essentially reusable

381
00:17:41.480 --> 00:17:44.460
something else, uh,

382
00:17:44.460 --> 00:17:47.440
that would actually protect the spacecraft from the intense heat of

383
00:17:47.440 --> 00:17:50.440
reentry. And it's a team at Texas A and

384
00:17:50.440 --> 00:17:53.080
M University, uh, partnering with a

385
00:17:53.400 --> 00:17:55.960
private concern called Canopy

386
00:17:55.960 --> 00:17:58.270
Aerospace. And they've basically

387
00:17:59.870 --> 00:18:02.510
developed uh, a 3D printed substance,

388
00:18:03.340 --> 00:18:05.310
um, that releases gas

389
00:18:06.670 --> 00:18:09.670
when you've got the heat of re

390
00:18:09.670 --> 00:18:12.590
entry. Uh and the reason

391
00:18:12.590 --> 00:18:14.910
that's interesting is that gas

392
00:18:15.880 --> 00:18:18.710
ah, has a very low conductivity of

393
00:18:18.710 --> 00:18:21.310
heat. Uh unlike you know, a piece of

394
00:18:21.630 --> 00:18:24.470
metal or something like that which conducts heat very, very

395
00:18:24.470 --> 00:18:27.310
well. Gas is pretty poor at conducting heat.

396
00:18:27.960 --> 00:18:30.570
Uh, and it's actually, you know, you've got

397
00:18:31.610 --> 00:18:34.290
a lot of uh, you know, why put it. Putting,

398
00:18:34.290 --> 00:18:37.290
putting air in the space between your inner and outside

399
00:18:37.370 --> 00:18:40.170
walls provides a bit of heat insulation and things of that

400
00:18:40.170 --> 00:18:43.030
sort. Uh, it's um, a um,

401
00:18:43.130 --> 00:18:45.970
good heat insulator. So if you

402
00:18:45.970 --> 00:18:48.970
can make something that will release gas

403
00:18:49.690 --> 00:18:52.500
as it enters the space, uh,

404
00:18:52.810 --> 00:18:55.650
as the spacecraft enters the atmosphere, then you might

405
00:18:55.650 --> 00:18:57.850
well find that you've got the situation

406
00:18:58.410 --> 00:19:01.050
where you've got uh, something that's effect

407
00:19:01.510 --> 00:19:04.350
reusable and that you don't have to replace every

408
00:19:04.350 --> 00:19:07.270
time. And it, and the material itself is a,

409
00:19:07.670 --> 00:19:10.310
it's a 3D printed silicon carbide,

410
00:19:10.760 --> 00:19:13.590
uh, and it is strong

411
00:19:13.830 --> 00:19:15.670
and I'm quoting here from the um,

412
00:19:16.870 --> 00:19:19.670
Space.com article about this, which is a very nice

413
00:19:19.670 --> 00:19:22.070
description, uh, written by Samantha

414
00:19:22.070 --> 00:19:25.070
Mathewson a few days ago or a day or so

415
00:19:25.070 --> 00:19:27.790
ago. Uh, uh, it's

416
00:19:27.790 --> 00:19:30.520
designed to be strong enough to withstand

417
00:19:30.600 --> 00:19:33.480
extreme atmospheric pressures, yet poor enough

418
00:19:33.480 --> 00:19:36.120
for the coolant to sweat through. Uh,

419
00:19:36.440 --> 00:19:39.280
and uh, she says prototypes are being tested at the

420
00:19:39.280 --> 00:19:42.240
university to evaluate the material's ability to sweat and

421
00:19:42.240 --> 00:19:44.440
how well, the gas that is released

422
00:19:44.600 --> 00:19:47.480
insulates a spacecraft. Uh, so

423
00:19:47.640 --> 00:19:50.640
it is. Yeah, um, it's a really interesting step.

424
00:19:50.640 --> 00:19:53.320
You know, um, what struck me about this

425
00:19:53.640 --> 00:19:56.510
is we've been using these ablative

426
00:19:56.510 --> 00:19:59.390
shields since, well, the Mercury

427
00:19:59.390 --> 00:20:01.910
capsule back in 1960,

428
00:20:02.070 --> 00:20:05.030
whenever it was 62, I think, Mercury,

429
00:20:05.510 --> 00:20:08.230
maybe 63. Um, and

430
00:20:08.230 --> 00:20:10.990
they're still being used. They're still on the

431
00:20:10.990 --> 00:20:13.550
Orion capsule, which is just a giant version of

432
00:20:13.550 --> 00:20:16.430
Mercury in some ways. Uh, and it's great

433
00:20:16.430 --> 00:20:19.390
to see people thinking outside the box as to whether we can

434
00:20:19.390 --> 00:20:22.090
find better ways to do this and actually create, um,

435
00:20:22.360 --> 00:20:24.680
you know, create new materials, given

436
00:20:25.320 --> 00:20:28.120
where we've got to today in things like 3D printing,

437
00:20:28.480 --> 00:20:30.840
uh, create new materials that can do the job better.

438
00:20:31.400 --> 00:20:34.280
Andrew Dunkley: Yeah, I suppose the only way to really test this would be

439
00:20:34.280 --> 00:20:37.079
to create this, this new form

440
00:20:37.079 --> 00:20:39.840
of shielding and send one up and bring it back

441
00:20:39.840 --> 00:20:42.200
and see if it survives, basically. And

442
00:20:43.560 --> 00:20:46.280
you wouldn't want to sort of, um, go up there

443
00:20:46.280 --> 00:20:48.080
unchecked and go, okay, we're going to test this new.

444
00:20:49.350 --> 00:20:52.190
Professor Fred Watson: Yeah, no, you wouldn't, you wouldn't want

445
00:20:52.190 --> 00:20:54.870
that. Um, uh, they've used

446
00:20:55.110 --> 00:20:58.030
hypersonic, uh, uh, wind tunnels to

447
00:20:58.030 --> 00:21:01.030
test it. So, and these are things that blow the wind along at

448
00:21:01.270 --> 00:21:04.189
several times the speed of sound. And so they've got a good idea

449
00:21:04.189 --> 00:21:05.430
that this is going to work, I think.

450
00:21:05.510 --> 00:21:08.510
Andrew Dunkley: Yeah. As we've seen though, with the space shuttle, all

451
00:21:08.510 --> 00:21:10.310
it takes is a tiny little

452
00:21:11.190 --> 00:21:13.910
crack in a tile to cause a major

453
00:21:13.910 --> 00:21:16.790
catastrophe. I'll never forget that.

454
00:21:16.900 --> 00:21:19.690
Um, but, but, um, I would

455
00:21:19.690 --> 00:21:22.450
imagine with a heat shield type of approach like

456
00:21:22.450 --> 00:21:25.250
this, the gas that too could be

457
00:21:25.250 --> 00:21:28.170
exposed if one of the vents or whatever it is

458
00:21:28.170 --> 00:21:30.050
they use to release the gas fails.

459
00:21:30.930 --> 00:21:33.570
Professor Fred Watson: Yes, I guess that's right.

460
00:21:33.810 --> 00:21:36.610
There'll always be, um, some sort of failure,

461
00:21:37.060 --> 00:21:40.050
uh, possibility, uh, and the trick is

462
00:21:40.050 --> 00:21:42.050
to reduce those as much as possible.

463
00:21:42.610 --> 00:21:45.210
Andrew Dunkley: Indeed. Uh, well, uh, it will be really

464
00:21:45.210 --> 00:21:47.870
interesting to see how this develops. It could, could

465
00:21:47.870 --> 00:21:50.550
be one of the, um, the big leaps

466
00:21:50.550 --> 00:21:52.870
forward in terms of getting

467
00:21:52.950 --> 00:21:55.190
spacecraft back into Earth without having to

468
00:21:55.190 --> 00:21:57.350
constantly regenerate,

469
00:21:57.940 --> 00:22:00.790
um, shields. Because, uh, that's what happens at the

470
00:22:00.790 --> 00:22:03.670
moment. Once a heat shield has been used, you can't

471
00:22:03.670 --> 00:22:06.470
use it again. It's the same with the tiles on the space

472
00:22:06.470 --> 00:22:09.310
shuttle. You, you have to replace them after every

473
00:22:09.310 --> 00:22:12.310
mission. Apparently, uh, this could be a

474
00:22:12.390 --> 00:22:15.350
renewable resource, a renewable approach to the

475
00:22:15.350 --> 00:22:17.990
whole thing, which obviously would reduce

476
00:22:18.070 --> 00:22:20.890
costs ultimately. And it's still very expensive

477
00:22:20.890 --> 00:22:23.730
to get up there, send out your

478
00:22:23.730 --> 00:22:26.010
payload or whatever, and then get the

479
00:22:26.490 --> 00:22:28.820
hardware back to Earth. So, um,

480
00:22:29.840 --> 00:22:31.450
uh, it's Been a long time coming.

481
00:22:32.730 --> 00:22:35.290
We're coming up on 100 years of space flight and

482
00:22:35.850 --> 00:22:38.730
it's taken three quarters of that time to

483
00:22:38.730 --> 00:22:41.650
come up with a new idea. So fingers crossed that this

484
00:22:41.650 --> 00:22:44.490
is actually the answer and who knows what else they might

485
00:22:44.490 --> 00:22:47.000
figure out down the track that could do the job. So

486
00:22:47.390 --> 00:22:50.310
um, I suppose a question that pops to mind

487
00:22:50.310 --> 00:22:53.190
and this is sort of a very dumb question I

488
00:22:53.190 --> 00:22:56.030
suppose, um, why can't they just re, enter

489
00:22:56.030 --> 00:22:58.990
slowly to avoid the heat? I'm guessing

490
00:22:58.990 --> 00:23:00.270
you wouldn't get back in.

491
00:23:01.290 --> 00:23:03.950
Professor Fred Watson: Um, you're limited by, you know, the

492
00:23:04.430 --> 00:23:07.070
mechanics of space flight. So um,

493
00:23:07.230 --> 00:23:10.070
anything in space that's you know, that's not

494
00:23:10.070 --> 00:23:12.990
coming back to Earth is orbiting at

495
00:23:13.110 --> 00:23:16.040
uh, nearly eight kilometres per second. And

496
00:23:16.490 --> 00:23:19.360
uh, that's why you need such a big rocket to put

497
00:23:19.360 --> 00:23:22.360
things into orbit. Because you've got to not only get the height,

498
00:23:22.920 --> 00:23:25.840
uh, to two or 300 kilometres, but also to

499
00:23:25.840 --> 00:23:28.720
push it into this high velocity with respect

500
00:23:28.720 --> 00:23:31.400
to the Earth's surface. And when you come back

501
00:23:32.120 --> 00:23:35.000
you've somehow got to dump that velocity. You've got to kill it

502
00:23:35.000 --> 00:23:37.880
somehow. Now you know, I do remember

503
00:23:38.040 --> 00:23:41.040
when I used to read Dundeere, the uh, pilot of

504
00:23:41.040 --> 00:23:44.010
the future in the Eagle. They, they used

505
00:23:44.080 --> 00:23:46.920
um, what they called reactor rockets. So you had uh,

506
00:23:46.920 --> 00:23:49.770
the spacecraft was in orbit and

507
00:23:49.770 --> 00:23:52.610
then uh, the command that Captain

508
00:23:52.610 --> 00:23:55.530
Dan Dare said was blower reactors and that

509
00:23:55.530 --> 00:23:58.250
was forward firing rockets that slowed the

510
00:23:58.250 --> 00:24:00.810
spacecraft down. And that's what they still do.

511
00:24:01.050 --> 00:24:03.770
They fire forward firing rockets

512
00:24:03.930 --> 00:24:06.690
to slow the spacecraft down. But unless

513
00:24:06.690 --> 00:24:09.650
you've got the same amount of fuel as you used to put it

514
00:24:09.650 --> 00:24:12.460
up there, you can't use that forward

515
00:24:12.460 --> 00:24:15.460
firing rocket to gently land it on the planet's

516
00:24:15.460 --> 00:24:18.380
surface. You've got to have something else. And uh, that something else is

517
00:24:18.380 --> 00:24:21.300
aero braking which is using the atmosphere to slow the

518
00:24:21.300 --> 00:24:23.820
spacecraft down. That's traditionally what

519
00:24:24.060 --> 00:24:27.060
has been used. It's the only way we have available at the moment until

520
00:24:27.060 --> 00:24:30.060
somebody invents something that doesn't need as much fuel

521
00:24:30.060 --> 00:24:32.460
to slow you down as uh, it takes you up there.

522
00:24:33.340 --> 00:24:35.420
Andrew Dunkley: Well that time will probably come. But

523
00:24:36.540 --> 00:24:39.500
for now making your spacecraft sweat could

524
00:24:39.500 --> 00:24:42.120
be uh, the new approach. And if you uh,

525
00:24:42.440 --> 00:24:44.720
are interested in that story, uh, as Fred Watson said,

526
00:24:44.720 --> 00:24:46.520
it's@space.com.

527
00:24:49.240 --> 00:24:52.200
okay, we checked all four systems and team with a go

528
00:24:52.200 --> 00:24:53.080
Space Nats.

529
00:24:53.640 --> 00:24:56.360
Okay Fred Watson, our final ah, story today

530
00:24:56.440 --> 00:24:59.400
is a very scary one because um, we

531
00:24:59.400 --> 00:25:02.160
might not be here next week or maybe it's a

532
00:25:02.160 --> 00:25:04.960
billion years. I always get the two mixed

533
00:25:04.960 --> 00:25:07.680
up. Uh, but um, on a serious

534
00:25:07.680 --> 00:25:10.520
note, uh, some Dutch scientists have come up with

535
00:25:10.760 --> 00:25:13.640
a new theory as to when the universe will end.

536
00:25:14.420 --> 00:25:17.220
And it is a heck of a lot sooner

537
00:25:17.700 --> 00:25:20.020
than we originally thought if they are right.

538
00:25:24.100 --> 00:25:26.580
Professor Fred Watson: Indeed it is. Uh, so here are the numbers,

539
00:25:26.820 --> 00:25:29.780
okay. Uh, because we might as well start with

540
00:25:29.780 --> 00:25:32.340
that. We used to think

541
00:25:33.140 --> 00:25:35.540
that the universe would die

542
00:25:36.260 --> 00:25:38.740
in 10 to the power 1100

543
00:25:39.060 --> 00:25:41.620
years. So that is a one with 1100

544
00:25:41.620 --> 00:25:44.610
zeros after it. It, that's how long we thought it would

545
00:25:44.930 --> 00:25:47.090
take to die. The new

546
00:25:48.210 --> 00:25:50.970
calculation uh, is only. It's a mere

547
00:25:50.970 --> 00:25:53.850
10 to the power 78 years. And

548
00:25:53.850 --> 00:25:56.770
that's 10 followed by, sorry one

549
00:25:56.770 --> 00:25:58.370
followed by 78 zeros.

550
00:25:59.490 --> 00:26:02.250
Look, that's ah, one heck of a

551
00:26:02.250 --> 00:26:05.010
difference, isn't it? It's a factor of more

552
00:26:05.010 --> 00:26:08.010
than 10 different uh, uh,

553
00:26:08.010 --> 00:26:10.890
it's a factor of more than 10 in exponent, which means that it's a

554
00:26:10.890 --> 00:26:13.840
very much different different. Um, so yes,

555
00:26:13.840 --> 00:26:16.680
the universe has only got really a brief period of 10 to

556
00:26:16.680 --> 00:26:19.400
the 78 years to last. Um but

557
00:26:19.400 --> 00:26:22.320
let's cut to the reason why these scientists are

558
00:26:22.320 --> 00:26:24.840
ah, uh, making these

559
00:26:25.160 --> 00:26:28.119
calculations. They're um, scientists actually in the

560
00:26:28.119 --> 00:26:30.840
Netherlands. Uh, and what they've

561
00:26:30.840 --> 00:26:33.000
done is they've looked at

562
00:26:33.160 --> 00:26:35.920
Hawking radiation. And

563
00:26:35.920 --> 00:26:38.680
that is the, the trick to this,

564
00:26:38.680 --> 00:26:41.000
this whole calculation. Hawking radiation

565
00:26:41.400 --> 00:26:44.300
is uh, as we know, the rad that

566
00:26:44.300 --> 00:26:47.220
leaks from a black hole. Uh which

567
00:26:47.220 --> 00:26:50.020
is a quantum physics effect because uh,

568
00:26:50.020 --> 00:26:52.940
relativity says nothing can come out of a black hole. But quantum

569
00:26:52.940 --> 00:26:55.780
mechanics says well they can evaporate very, very slowly.

570
00:26:56.980 --> 00:26:59.620
And they do. Uh, there's all the

571
00:26:59.620 --> 00:27:02.260
evidence suggests that Hawking radiation is a real thing.

572
00:27:02.500 --> 00:27:05.460
And so what these calculations are about is how long it

573
00:27:05.460 --> 00:27:08.300
takes everything in the universe to come to an

574
00:27:08.300 --> 00:27:11.270
end by Hawking radiation. Um, and they don't

575
00:27:11.270 --> 00:27:14.190
just cover black holes. They cover everything.

576
00:27:14.350 --> 00:27:17.150
They cover um, neutron stars which

577
00:27:17.150 --> 00:27:19.870
are kind of failed black holes. They cover white

578
00:27:19.870 --> 00:27:22.430
dwarf stars which are kind of failed neutron stars.

579
00:27:22.820 --> 00:27:25.350
Um, and these all have um, a

580
00:27:25.350 --> 00:27:27.710
Hawking age. And I think actually

581
00:27:28.480 --> 00:27:31.470
um, the original calculation of 10 to the 1100

582
00:27:32.110 --> 00:27:34.340
years was um, um,

583
00:27:34.590 --> 00:27:37.390
basically coming from just the lifetime of white

584
00:27:37.390 --> 00:27:39.820
dwarf stars does, but

585
00:27:40.360 --> 00:27:42.940
uh, the new calculation have

586
00:27:43.380 --> 00:27:45.130
uh, have um,

587
00:27:46.140 --> 00:27:48.620
essentially said uh, the,

588
00:27:49.660 --> 00:27:52.620
the decay time for white dwarfs is

589
00:27:53.340 --> 00:27:56.060
uh, sooner than we

590
00:27:56.140 --> 00:27:58.860
thought. Uh, I think actually the white dwarf decay

591
00:27:58.860 --> 00:28:01.820
time originally didn't include Hawking radiation. I think it

592
00:28:01.820 --> 00:28:04.660
was just how long it takes to cool down to a completely

593
00:28:04.660 --> 00:28:07.610
inert object. So um, the new calculation

594
00:28:07.690 --> 00:28:10.250
takes into account uh, the

595
00:28:10.890 --> 00:28:13.870
basics of Hawking radiation. Um,

596
00:28:14.810 --> 00:28:17.370
they've got some nice other

597
00:28:17.770 --> 00:28:20.200
figures as well because uh,

598
00:28:21.050 --> 00:28:23.210
they can Work out how long

599
00:28:23.770 --> 00:28:26.770
neutron stars take to decay. That's 10

600
00:28:26.770 --> 00:28:29.710
to the power 67 years. Um,

601
00:28:29.710 --> 00:28:32.350
they can work out how long. Long the

602
00:28:32.350 --> 00:28:35.230
moon will take to evaporate by human.

603
00:28:35.710 --> 00:28:38.390
Uh, Sorry, By Hawking radiation.

604
00:28:38.390 --> 00:28:41.230
And how long it will take a human to evaporate.

605
00:28:41.950 --> 00:28:44.950
And those figures are respectively. Well, they're the same

606
00:28:44.950 --> 00:28:47.790
10 to the power 90. So you and I, as we sit

607
00:28:47.790 --> 00:28:48.830
here, Andrew.

608
00:28:49.070 --> 00:28:49.550
Andrew Dunkley: Yeah.

609
00:28:49.890 --> 00:28:52.750
Professor Fred Watson: Uh, we will evaporate in 10 to the power 90

610
00:28:52.910 --> 00:28:55.350
years, which means we actually outlast the

611
00:28:55.350 --> 00:28:57.910
universe because the universe is going to

612
00:28:57.910 --> 00:29:00.730
evaporate in. In 10 to the 78 years.

613
00:29:01.130 --> 00:29:04.130
Uh, so we're, we're doing well there. How can we

614
00:29:04.130 --> 00:29:06.890
outlast the universe? I'm not sure what the answer to that

615
00:29:06.890 --> 00:29:07.290
is.

616
00:29:08.970 --> 00:29:11.650
Andrew Dunkley: Yeah, well, nothing, um, could. If the

617
00:29:11.650 --> 00:29:14.370
universe comes to a grinding halt, that's the end of everything,

618
00:29:14.370 --> 00:29:17.330
isn't it? Ah, to qualify this, you've

619
00:29:17.330 --> 00:29:20.240
got to accept that, um, they're talking about the, the, uh,

620
00:29:20.250 --> 00:29:23.090
fading out of everything. That's correct. But the

621
00:29:23.090 --> 00:29:24.950
universe will still be there. It'll just be dead.

622
00:29:26.300 --> 00:29:28.740
Professor Fred Watson: Unless, uh, the, you know, the

623
00:29:28.740 --> 00:29:31.580
accelerated expansion of the universe results in the Big Rip,

624
00:29:31.820 --> 00:29:34.540
which could come a lot sooner than those evaporation

625
00:29:34.540 --> 00:29:37.500
times. So you're quite right. This is assuming

626
00:29:37.500 --> 00:29:40.180
nothing else happens in the universe. The universe is as boring as

627
00:29:40.180 --> 00:29:42.140
anything. Uh, and things just

628
00:29:42.620 --> 00:29:45.540
evaporate by Hawking radiation. That's

629
00:29:45.540 --> 00:29:46.860
the numbers that you get.

630
00:29:47.260 --> 00:29:50.140
Andrew Dunkley: Yeah. And there was one other thing we left out of that, and that was

631
00:29:50.140 --> 00:29:52.540
the, um, um, evaporation of brown

632
00:29:52.540 --> 00:29:55.260
dwarfs, um, because they're failed Disney

633
00:29:55.260 --> 00:29:58.170
actors, so got to take that into

634
00:29:58.170 --> 00:30:01.090
account too. And that only takes 88 years.

635
00:30:01.730 --> 00:30:04.570
Professor Fred Watson: Okay. Very good.

636
00:30:04.570 --> 00:30:07.490
That's a neat calculation. I think you should write. That's up to the

637
00:30:07.650 --> 00:30:08.930
conversation, Andrew.

638
00:30:10.770 --> 00:30:13.590
Andrew Dunkley: It's terrible, Jack. Horrible. Yeah. Um,

639
00:30:13.890 --> 00:30:16.850
no, but it is, uh, rather fascinating. Um, so do we

640
00:30:16.850 --> 00:30:19.850
know. I don't know if you said it in number of years, what 10

641
00:30:19.850 --> 00:30:22.490
to the 78 actually means for the

642
00:30:22.490 --> 00:30:22.910
universe.

643
00:30:25.300 --> 00:30:28.180
Professor Fred Watson: Yeah, well, yes, uh, just means one followed by

644
00:30:28.180 --> 00:30:30.500
78 zeros. It's a long time.

645
00:30:30.500 --> 00:30:31.540
Andrew Dunkley: Still a long time.

646
00:30:32.180 --> 00:30:34.220
Professor Fred Watson: Yeah. And, um, we should be right to.

647
00:30:34.220 --> 00:30:36.340
Andrew Dunkley: Pay the, the water rates next week then.

648
00:30:36.420 --> 00:30:39.060
Professor Fred Watson: That's right. I mean, you know, put it in perspective.

649
00:30:39.760 --> 00:30:41.940
Uh, the Earth is probably going to get melted

650
00:30:42.500 --> 00:30:45.260
within maybe 4 billion years.

651
00:30:45.260 --> 00:30:48.020
What's that? 4 times 10 to 9 years. So.

652
00:30:48.100 --> 00:30:50.290
Yeah, yeah, yeah, that's, uh.

653
00:30:51.140 --> 00:30:53.940
That's. That's going to be a much more immediate

654
00:30:54.180 --> 00:30:57.060
problem, uh, for us than the evaporation of everything by

655
00:30:57.060 --> 00:30:57.980
Hawking radius.

656
00:30:57.980 --> 00:31:00.980
Andrew Dunkley: That's assuming humanity has actually survived that long, which

657
00:31:00.980 --> 00:31:02.820
is totally different.

658
00:31:02.900 --> 00:31:03.940
Professor Fred Watson: Yes, we might.

659
00:31:03.940 --> 00:31:05.700
Andrew Dunkley: Argument, theory, whatever you like.

660
00:31:05.920 --> 00:31:06.340
Professor Fred Watson: M yeah.

661
00:31:06.340 --> 00:31:09.220
Andrew Dunkley: All right. Uh, that story available through

662
00:31:09.460 --> 00:31:12.340
fizz.org p h y s.org

663
00:31:12.660 --> 00:31:15.140
if you want to read up on it. It's really, really interesting.

664
00:31:15.900 --> 00:31:18.850
Uh, and that brings us to the end. Fred, thank you very

665
00:31:18.850 --> 00:31:19.170
much.

666
00:31:19.650 --> 00:31:22.650
Professor Fred Watson: Pleasure, Andrew, as always. And we'll speak again soon. I'm sure

667
00:31:22.650 --> 00:31:23.410
we will.

668
00:31:23.730 --> 00:31:26.730
Andrew Dunkley: And, uh, looking forward to it. And don't forget to visit us

669
00:31:26.730 --> 00:31:29.610
online at our website and visit the shop

670
00:31:29.610 --> 00:31:32.530
while you're there or just have a look around. And that's

671
00:31:32.530 --> 00:31:34.850
at, uh, spacenutspodcast.com or

672
00:31:34.850 --> 00:31:37.690
spacenuts IO. Uh, I would

673
00:31:37.690 --> 00:31:40.530
have said thanks to Huw in the studio, but he couldn't be with us

674
00:31:40.530 --> 00:31:43.050
today because he reached the age of 10 to the

675
00:31:43.050 --> 00:31:45.690
78. And that was the end of that

676
00:31:46.570 --> 00:31:49.530
from me, Andrew Dunkley. Thanks for your company. We'll see you

677
00:31:49.530 --> 00:31:51.930
on the next episode of Space Nuts. Bye. Bye.

678
00:31:53.130 --> 00:31:55.930
Generic: You've been listening to the Space Nuts Podcast,

679
00:31:57.530 --> 00:32:00.330
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680
00:32:00.490 --> 00:32:03.250
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681
00:32:03.250 --> 00:32:04.970
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682
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683
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684
00:32:09.970 --> 00:32:11.130
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