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Mars' Hidden Oceans, Sweat Shields & The Universe's Sudden End · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Andrew Dunkley: Hi there. This is Space Nuts, where we talk
• 0:02
  astronomy and space science. And my name is
• 0:05
  Andrew Dunkley, your host. It's good to have
• 0:06
  your company on this episode. We're going to
• 0:09
  Mars, uh, where we're going to talk about
• 0:12
  water. Now, water is a very common Martian
• 0:15
  topic, uh, but this story
• 0:18
  is going to throw a completely different
• 0:20
  light on Mars water. And we'll tell you
• 0:23
  why. Uh, there's also a great
• 0:26
  idea that's being put forward to
• 0:28
  help spacecraft, uh, re enter
• 0:31
  Earth's atmosphere. Because up until now,
• 0:33
  we've used heat shields and tiles.
• 0:36
  Now they think they've come up with something
• 0:38
  completely different. It's called Sweat
• 0:41
  and the Universe RIP
• 0:44
  Yep, we're going to see it all end much
• 0:47
  sooner than we expected. We'll talk about all
• 0:49
  of that on this episode 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.
• 1:09
  For more it is Professor Fred Watson Watson,
• 1:11
  astronomer at large. Hello, Fred Watson.
• 1:13
  Professor Fred Watson: Uh, Andrew. How are you doing?
• 1:15
  Andrew Dunkley: I'm doing quite well, thank you very much.
• 1:17
  Are you.
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  Professor Fred Watson: What a surprise to see it. Yeah, I'm very
• 1:20
  well, thank you. Yeah.
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  Andrew Dunkley: Oh, it is a surprise to see you there. I
• 1:23
  mean, do you like my new background? I'm
• 1:26
  going to change the background every week on
• 1:27
  my studio.
• 1:28
  Professor Fred Watson: I think that's a good idea. Uh, and, um, I do
• 1:31
  like it. Uh, it's a, uh, place that's
• 1:34
  close to my heart as well as yours. It's a
• 1:36
  great place.
• 1:37
  Andrew Dunkley: Well, isn't that the saying, I left
• 1:40
  my heart in San Francisco.
• 1:42
  Professor Fred Watson: Yeah, you probably did.
• 1:45
  Andrew Dunkley: That's a photo I took after we crossed the
• 1:47
  Golden Gate Bridge looking back to San
• 1:49
  Francisco. So thought I'd use that as my
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  backdrop today.
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  Professor Fred Watson: The, um, second line of that song is a good
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  one as well. I left my knees in old
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  Peru.
• 2:02
  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
• 2:10
  you about the driverless taxis they've got.
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  But there's so much more going for it. Those
• 2:15
  cable, uh, cars are fantastic. Um,
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  we obviously did the tourist thing and did a
• 2:20
  ride on one of those and then, you know, did
• 2:23
  the walk down Lombard street, that, uh,
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  zigzaggy street that, um, has become quite
• 2:28
  famous. And I don't know how many movies and
• 2:30
  TV shows it's been in, but, um.
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  And it's like all of these things that when
• 2:35
  you see them on tv, you think, oh, wow, got
• 2:38
  to go see that. And then you get there and
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  go, oh, it's. It's a lot smaller than I
• 2:42
  thought. Ah. But
• 2:45
  yeah, um, I don't know what the price of a
• 2:48
  house is on Lombard street, but it's, uh,
• 2:50
  beautiful homes there.
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  Professor Fred Watson: Yes.
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  Andrew Dunkley: But overall, a beautiful city. Beautiful
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  city. I'd go back there tomorrow. Uh, we
• 2:58
  better get into it, Fred Watson.
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  And our first topic, uh, today
• 3:02
  is the water on Mars. Or in this
• 3:05
  case, according to a new theory inside
• 3:08
  Mars. And we're talking about massive
• 3:11
  amounts of water.
• 3:13
  Professor Fred Watson: Indeed. That's right, we are. It's not just a
• 3:16
  few drips or drops. Uh, so the
• 3:19
  story, uh, the star of the story, Andrew,
• 3:22
  is NASA's InSight spacecraft,
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  which it's almost. It's more
• 3:28
  than a decade ago now. I think that, uh,
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  Insight landed, uh, you might remember it
• 3:32
  landed in the Arctic region, region of Mars.
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  And, um, basically did
• 3:37
  one summer's worth of work. Because
• 3:40
  we knew that once it got into winter on Mars,
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  the spacecraft would freeze and all the
• 3:45
  electronics would die and it would pass away,
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  which it did. Uh, it's still there, of
• 3:49
  course, but it's inactive. Um, so a
• 3:52
  great, uh, mission, uh, it had
• 3:55
  one little, um, hiccup in that
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  the thermometer that they were trying to dig
• 3:59
  into the ground didn't get dug in. You might
• 4:01
  remember we covered that on Spacenauts. But
• 4:04
  what worked a treat was the seismometer.
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  Because it had a very sensitive
• 4:09
  seismometer able, uh, to listen
• 4:13
  to Marsquakes. Uh, and,
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  um, Marsquakes are caused by a number of
• 4:18
  things. Um, impacting, uh,
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  meteorites actually cause a little quake.
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  And they also think there's some residual.
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  Not exactly plate tectonics, but just slips
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  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
• 4:50
  ago, was warm and wet. Uh, the
• 4:53
  evidence is in your face in many ways. You
• 4:55
  can see evidence of beaches and river
• 4:58
  channels. And, you know, the northern
• 5:00
  hemisphere of Mars is much smoother and
• 5:02
  flatter than the southern hemisphere, which
• 5:04
  we think is because there was possibly an
• 5:05
  ocean there. So all the evidence, science,
• 5:07
  uh, is that during that early period in
• 5:10
  Mars's history. And just remember that all
• 5:12
  the planets are 4.6 billion years old or
• 5:15
  thereabouts. 4.7, something like that.
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  4, uh.1 billion years is only half a billion
• 5:20
  years after the origin of Mars. But, uh,
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  we think that that was more or less the start
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  of when it was a warm and wet world and that
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  lasted for nearly a billion years. A little
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  bit more 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
• 5:42
  as dry as dust and in fact it's got humidity
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  effectively not quite but effectively of
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  zero. Very, very low humidity. Um
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  so the questions have always been where did
• 5:51
  the surface water go? We know that
• 5:55
  uh because Mars does not have a strong
• 5:57
  magnetic field it's bombarded intensely by
• 6:00
  the solar wind, uh and that tends
• 6:03
  to separate any water
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  uh, vapour uh into its component
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  atoms, hydrogen and oxygen and they
• 6:11
  then basically waft off into space. And we
• 6:14
  know that's happening because there's uh, a
• 6:16
  spacecraft called Marvin or Maven, uh which
• 6:18
  is still active in uh, orbit around Mars and
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  that can see this stuff all leaking away.
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  So we know that was part of the story. But
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  um, the planetary scientists who look at Mars
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  in detail say that's not enough. We can't
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  actually account for, for all the water that
• 6:33
  must have been there by it just disappearing
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  into space. Um, we know some of it's frozen
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  in the polar caps uh of Mars.
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  Um, and probably you know,
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  hydrolyzed minerals. There have been minerals
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  on Mars surface have been affected by water.
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  Uh that's still the case however
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  uh, there must be more. And
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  there was a calculation done um, I think by
• 7:00
  the research group that's uh, done this work
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  with the Insights, um, lander
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  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.
• 7:21
  Professor Fred Watson: Yeah, uh,
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  it's gone um, where. And that's not an
• 7:27
  insignificant amount of water. Remember Mars
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  is only half the diameter of Earth so it's
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  not like uh, an earthly amount but it's a lot
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  of water, 700 to 900 metres deep across the
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  whole planet. So uh,
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  where's it gone? Uh and
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  you know, if we can find it, what, what might
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  it be like? So uh, now enter
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  uh insight. Uh and actually I was wrong. It's
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  not a decade ago. It was 2018 when Insight
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  landed uh and uh, did all that super
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  work with its sensitive seismometer.
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  Uh these scientists looked at
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  the vibrations that
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  come from um, any sort
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  of marsquake caused by as I mentioned
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  before, either slippage in the rock or uh, a
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  meteorite. Uh but you can look very
• 8:17
  accurately at ah, the um,
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  essentially the types of waves that you're
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  getting because, uh, there are pressure waves
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  and shear waves. I think they're called S
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  waves and P waves in the, um. Uh,
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  in the jargon of seismometry. But these
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  waves, seismographic waves,
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  tell you something about the material that
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  they are passing through. And that is
• 8:41
  where this, uh, story has gone. Because
• 8:44
  these scientists estimate, uh,
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  what they call a significant underground
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  anomaly exists, uh, in a
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  layer between five and a half and
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  eight kilometres below the surface. Because
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  they find that these shear waves move more
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  slowly, uh, in that region. And
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  the most likely explanation. And remember,
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  that's. That's a layer that's, you know, it's
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  two and a half kilometres, two and a half
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  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
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  bit like the aquifers. And we've got a great
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  one here in Australia, the great Artesian
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  Basin, uh, which is.
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  Andrew Dunkley: I'm sitting on it, right?
• 9:31
  Professor Fred Watson: You're sitting on it. That's right. You are.
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  Are your feet wet, Andrew, or.
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  Andrew Dunkley: No, no. We do have, as
• 9:37
  you know, several bores all over the city
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  here because, uh, we can
• 9:42
  tap the Great Artesian basin and, and
• 9:45
  get that water for domestic use. So we.
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  We kind of, um, take water from that
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  source as well as from river. The river is
• 9:54
  fed by a huge dam upstream which is
• 9:57
  bigger than Sydney Harbour.
• 9:59
  Professor Fred Watson: Uh.
• 9:59
  Andrew Dunkley: And. Yes, that's right, Farendom Dam. So, uh,
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  yeah, we, uh, definitely use
• 10:05
  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
• 10:12
  consequence of that, we will never run out of
• 10:15
  water because we sit on the Great
• 10:18
  Artesian basin, which basically stretches
• 10:21
  north to south across the entire continent
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  down, um, this sort of central, um, eastern
• 10:26
  section.
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  Professor Fred Watson: That's correct, yeah.
• 10:28
  Andrew Dunkley: Yeah. It's massive.
• 10:29
  Professor Fred Watson: It is massive.
• 10:30
  Andrew Dunkley: It's like an underground ocean, basically.
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  And that's what we're talking about with
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  Mars.
• 10:34
  Professor Fred Watson: That's exactly right. And so it's a really
• 10:37
  nice, um, you know, connection that we have
• 10:39
  here in Eastern Australia with Mars. Uh, this
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  sort of, you know, um. It's almost. The rock
• 10:45
  itself is sponge, like in the sense that it
• 10:48
  holds the water, the liquid water.
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  And the thinking is, uh, that because
• 10:53
  it's at a depth, as I said, a
• 10:56
  few kilometres, between five and a half and
• 10:58
  eight kilometres, um, the temperature
• 11:01
  there is warmer than it is on the surface by
• 11:03
  quite a long way because of just the internal
• 11:05
  heat of the planet. Uh, and so they think it
• 11:08
  is actually liquid, uh, and that fits the
• 11:11
  bill in terms of the seismic waves
• 11:14
  that they've detected, uh, that you've
• 11:16
  actually got this liquid water in
• 11:19
  porous rock. Um, and
• 11:22
  what's really nice about this story is,
• 11:25
  uh, that if that is, um, a global,
• 11:28
  uh, layer of rock, and it may well be,
• 11:31
  um, they calculate how much water
• 11:34
  is in it, uh, and sure enough,
• 11:37
  it's enough to cover Mars in a global
• 11:40
  ocean between. Well, the figures they quote
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  is between 520 and 780 metres
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  deep. Just about the same as what they think
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  is the missing water mass on Mars.
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  Andrew Dunkley: So this is sense. Yeah, I mean, this
• 11:53
  is still a maybe, not a definite,
• 11:56
  but the numbers certainly support it.
• 11:59
  That's what's really interesting about this
• 12:01
  story. Excuse me. And,
• 12:04
  uh, yeah, the question is, if
• 12:07
  we go to Mars, and
• 12:09
  I know you don't like this, but they will
• 12:11
  probably establish colonies there. If one man
• 12:14
  has his way, um, will they be able
• 12:17
  to access it? Could it. Could it actually
• 12:20
  hold microbial life and could you drink
• 12:23
  it?
• 12:24
  Professor Fred Watson: Uh, yes, that's right. I mean, the middle
• 12:26
  question there, the. The fact that there
• 12:28
  might be life in it, that's the one that's so
• 12:30
  intriguing. Uh, I think, I suspect
• 12:33
  at that depth you'd struggle to get it. But
• 12:35
  we do know. And again, this comes from
• 12:37
  Insight. Um. Uh, no, it wasn't.
• 12:40
  Insight was. It was Phoenix. Yes, Phoenix was
• 12:43
  a spacecraft like Insight, uh,
• 12:46
  which was actually, uh, the one that
• 12:49
  was in the Arctic. And so. I beg your pardon,
• 12:51
  I said something incorrect before. The
• 12:53
  INSIGHT was in the Arctic. Martian Arctic.
• 12:55
  But it wasn't. It was Phoenix 2 spacecraft
• 12:57
  which was very similar. Uh, one was for
• 12:59
  seismometry. INSIGHT was basically giving
• 13:02
  us sight of the inside of Mars and M.
• 13:05
  Phoenix was all about, uh,
• 13:09
  basically, um, sampling the surface rock.
• 13:12
  Uh, and, um, we remember
• 13:15
  those classic pictures, they scraped away the
• 13:17
  top layer.
• 13:18
  Andrew Dunkley: Of soil and there was ice.
• 13:20
  Professor Fred Watson: There's ice underneath it.
• 13:21
  Andrew Dunkley: Yeah, yeah, yeah. Um,
• 13:24
  it was like a kid had been up there with his
• 13:26
  Tonka tractor and he scraped the top of
• 13:29
  the dirt and turned white.
• 13:33
  Professor Fred Watson: That's right. So, uh, that is in the Arctic
• 13:36
  region, but that's telling you there's a
• 13:37
  permafrost of water and there is
• 13:40
  a huge amount there as well. Uh, but, you
• 13:43
  know, to find liquid water now, um,
• 13:46
  whether that's drinkable, probably if you
• 13:48
  purify it, might have minerals in it that
• 13:50
  you'd like to get rid of. But, uh, I think it
• 13:53
  will be drinkable. Um, but yes, the
• 13:55
  intriguing thing is, as you said, is whether
• 13:57
  it could harbour Martian Biology
• 14:00
  that's uh, really, really interesting. Uh,
• 14:03
  and, and in that regard, um, you know
• 14:05
  we've talked about the planetary protection
• 14:07
  rules before and uh, um,
• 14:10
  how much of spacecraft has to be sterilised
• 14:13
  before it's sent to Mars. If it's going
• 14:15
  anywhere where liquid water could exist, what
• 14:18
  it would do. This would mean that we would
• 14:20
  have to be doubly careful sort of no matter
• 14:22
  where you're going on Mars because deep under
• 14:24
  the surface there might well be Martian
• 14:26
  microbes that wouldn't like earthly microbes
• 14:28
  if they found their way down through the
• 14:30
  rocks, so. Oh, uh, absolutely.
• 14:32
  Andrew Dunkley: And, and we've got evidence on Earth of that
• 14:34
  kind of contamination when like the Spanish
• 14:37
  went to South America and the South American
• 14:40
  people um, were exposed
• 14:43
  to diseases that just didn't exist in there.
• 14:45
  Professor Fred Watson: Wipe them out.
• 14:46
  Andrew Dunkley: Wipe them out.
• 14:47
  Professor Fred Watson: Almost completely similar things happened in
• 14:50
  our own country. Andrew as well.
• 14:52
  Andrew Dunkley: Yep, absolutely.
• 14:52
  Professor Fred Watson: Smallpox and things like that. And I should
• 14:54
  just talking about our country, I should
• 14:56
  mention that some of this work has been
• 14:57
  carried out by Australian investigators at
• 14:59
  the Australian National University as well as
• 15:02
  um, uh, scientists at the Chinese Academy of
• 15:05
  Sciences.
• 15:06
  Andrew Dunkley: Well hopefully there'll be some follow up to
• 15:09
  um, maybe confirm what they think.
• 15:13
  As I said, the numbers are stacking up in
• 15:15
  that favour and it will mean that if uh,
• 15:18
  that's true, um, Mars is not a
• 15:21
  dry dead planet. It's probably a water
• 15:24
  world, but a different kind of water. And
• 15:26
  we're seeing more and more of that throughout
• 15:28
  the solar system.
• 15:30
  Professor Fred Watson: We are indeed. That's right.
• 15:32
  Andrew Dunkley: Very exciting indeed. All right, if you'd
• 15:34
  like to read up on that you can uh, see
• 15:36
  that@the conversation.com
• 15:39
  website. This is Space Nuts Andrew
• 15:41
  Dunkley with Professor Fred Watson Watson.
• 15:48
  Space Nuts.
• 15:49
  Professor Fred Watson: Speaking of water.
• 15:50
  Andrew Dunkley: Well not quite but uh, we,
• 15:52
  we've seen over the
• 15:55
  entire space ah, race to
• 15:58
  date, um, which began way back in the middle
• 16:01
  of the last century, uh, that if you wanted
• 16:04
  to get a spacecraft back into the
• 16:06
  atmosphere you had to be prepared for it to
• 16:09
  potentially burn up uh, unless you put a heat
• 16:12
  shield on it. And later those heat uh,
• 16:15
  absorbent tiles that were made famous by the
• 16:18
  space shuttle and my son has actually got one
• 16:20
  of those tiles at his place because he got it
• 16:23
  as a secret Santa through um, one of the uh,
• 16:26
  social media websites when they used to do
• 16:28
  that um, and the warning came do not lick
• 16:31
  the tile. Well apparently it's very toxic.
• 16:34
  Um, so um, that's how it's been
• 16:37
  done to date. But now they've come up with a
• 16:39
  new idea that basically
• 16:42
  involves spacecraft sweating to
• 16:45
  Stay cool as they come back into the
• 16:47
  atmosphere. This is really fascinating.
• 16:51
  Professor Fred Watson: Uh, it's extraordinary. Yeah. And what you've
• 16:53
  said is absolutely right. Um,
• 16:57
  uh, the traditional uh, heat shield
• 17:00
  is called an ablative shield because it
• 17:02
  ablates the heat, takes it away. Uh,
• 17:04
  and that means that you only use them once.
• 17:08
  So um, that's an issue for
• 17:10
  example with the Orion capsule which is um,
• 17:13
  going to be reused. Uh, this is the one that
• 17:15
  will take astronauts to the moon. Um, uh,
• 17:18
  and um, it's a pretty large piece of
• 17:21
  kit and every time you reuse it you've got to
• 17:24
  replace that ablative shield that's on there.
• 17:26
  Or ablative shield, however you pronounce it.
• 17:28
  It's on the back of the spacecraft. That's
• 17:30
  the bit that burns away, uh, as the
• 17:32
  spacecraft re enters. Uh, so, um,
• 17:35
  could you find a way of doing this, uh,
• 17:38
  which was essentially reusable
• 17:41
  something else, uh,
• 17:44
  that would actually protect the spacecraft
• 17:46
  from the intense heat of reentry. And it's
• 17:49
  a team at Texas A and M University, uh,
• 17:52
  partnering with a private concern
• 17:54
  called Canopy Aerospace. And they've
• 17:57
  basically developed uh, a
• 18:00
  3D printed substance, um,
• 18:03
  that releases gas
• 18:06
  when you've got the heat of re
• 18:09
  entry. Uh and the reason
• 18:12
  that's interesting is that gas
• 18:15
  ah, has a very low conductivity of
• 18:18
  heat. Uh unlike you know, a piece of
• 18:21
  metal or something like that which conducts
• 18:23
  heat very, very well. Gas is pretty poor at
• 18:26
  conducting heat. Uh, and it's actually,
• 18:29
  you know, you've got a lot of uh,
• 18:32
  you know, why put it. Putting, putting air in
• 18:35
  the space between your inner and outside
• 18:37
  walls provides a bit of heat insulation and
• 18:39
  things of that sort. Uh, it's
• 18:42
  um, a um, good heat insulator.
• 18:45
  So if you can make something that will
• 18:48
  release gas as it enters
• 18:50
  the space, uh, as the spacecraft
• 18:53
  enters the atmosphere, then you might well
• 18:56
  find that you've got the situation where
• 18:59
  you've got uh, something that's effect
• 19:01
  reusable and that you don't have to replace
• 19:04
  every time. And it, and the material itself
• 19:06
  is a, it's a 3D printed silicon
• 19:09
  carbide, uh, and it
• 19:12
  is strong and I'm quoting here from
• 19:15
  the um, Space.com article about
• 19:18
  this, which is a very nice description, uh,
• 19:21
  written by Samantha Mathewson a few days ago
• 19:24
  or a day or so ago. Uh,
• 19:27
  uh, it's designed to be strong enough to
• 19:30
  withstand extreme atmospheric pressures, yet
• 19:32
  poor enough for the coolant to sweat through.
• 19:36
  Uh, and uh, she says prototypes are being
• 19:38
  tested at the university to evaluate the
• 19:40
  material's ability to sweat and how well, the
• 19:43
  gas that is released insulates a spacecraft.
• 19:46
  Uh, so it is. Yeah, um,
• 19:49
  it's a really interesting step. You know, um,
• 19:51
  what struck me about this is
• 19:55
  we've been using these ablative shields
• 19:57
  since, well, the Mercury capsule back
• 20:00
  in 1960, whenever it was
• 20:02
  62, I think, Mercury, maybe
• 20:05
  63. Um, and they're
• 20:08
  still being used. They're still on the Orion
• 20:11
  capsule, which is just a giant version of
• 20:13
  Mercury in some ways. Uh, and it's great
• 20:16
  to see people thinking outside the box as to
• 20:18
  whether we can find better ways to do this
• 20:20
  and actually create, um, you know, create new
• 20:23
  materials, given where we've got to
• 20:26
  today in things like 3D printing, uh, create
• 20:28
  new materials that can do the job better.
• 20:31
  Andrew Dunkley: Yeah, I suppose the only way to really test
• 20:33
  this would be to create this, this
• 20:36
  new form of shielding and send one up and
• 20:39
  bring it back and see if it survives,
• 20:41
  basically. And you wouldn't want
• 20:44
  to sort of, um, go up there unchecked and go,
• 20:47
  okay, we're going to test this new.
• 20:49
  Professor Fred Watson: Yeah, no, you wouldn't, you wouldn't want
• 20:52
  that. Um, uh, they've used
• 20:55
  hypersonic, uh, uh, wind tunnels to
• 20:58
  test it. So, and these are things that blow
• 21:00
  the wind along at several times the speed of
• 21:02
  sound. And so they've got a good idea that
• 21:04
  this is going to work, I think.
• 21:05
  Andrew Dunkley: Yeah. As we've seen though, with the space
• 21:07
  shuttle, all it takes is a tiny little
• 21:11
  crack in a tile to cause a major
• 21:13
  catastrophe. I'll never forget that.
• 21:16
  Um, but, but, um, I would
• 21:19
  imagine with a heat shield type of approach
• 21:22
  like this, the gas that too could
• 21:25
  be exposed if one of the vents or whatever it
• 21:28
  is they use to release the gas fails.
• 21:30
  Professor Fred Watson: Yes, I guess that's right.
• 21:33
  There'll always be, um, some sort of failure,
• 21:37
  uh, possibility, uh, and the trick is
• 21:40
  to reduce those as much as possible.
• 21:42
  Andrew Dunkley: Indeed. Uh, well, uh, it will be really
• 21:45
  interesting to see how this develops. It
• 21:47
  could, could be one of the, um, the big
• 21:50
  leaps forward in terms of getting
• 21:52
  spacecraft back into Earth without having to
• 21:55
  constantly regenerate,
• 21:57
  um, shields. Because, uh, that's what happens
• 22:00
  at the moment. Once a heat shield has been
• 22:02
  used, you can't use it again. It's the same
• 22:04
  with the tiles on the space shuttle. You, you
• 22:07
  have to replace them after every mission.
• 22:09
  Apparently, uh, this could be a
• 22:12
  renewable resource, a renewable approach to
• 22:15
  the whole thing, which obviously would reduce
• 22:18
  costs ultimately. And it's still very
• 22:20
  expensive to get up there, send
• 22:23
  out your payload or whatever, and then get
• 22:25
  the hardware back to Earth. So,
• 22:28
  um, uh, it's Been a long time coming.
• 22:32
  We're coming up on 100 years of space flight
• 22:35
  and it's taken three quarters of that time
• 22:38
  to come up with a new idea. So fingers
• 22:41
  crossed that this is actually the answer and
• 22:43
  who knows what else they might figure out
• 22:45
  down the track that could do the job. So
• 22:47
  um, I suppose a question that pops to mind
• 22:50
  and this is sort of a very dumb question I
• 22:53
  suppose, um, why can't they just re, enter
• 22:56
  slowly to avoid the heat? I'm guessing
• 22:58
  you wouldn't get back in.
• 23:01
  Professor Fred Watson: Um, you're limited by, you know, the
• 23:04
  mechanics of space flight. So um,
• 23:07
  anything in space that's you know, that's not
• 23:10
  coming back to Earth is orbiting at
• 23:13
  uh, nearly eight kilometres per second. And
• 23:16
  uh, that's why you need such a big rocket to
• 23:19
  put things into orbit. Because you've got to
• 23:21
  not only get the height, uh, to two or
• 23:23
  300 kilometres, but also to push it into this
• 23:26
  high velocity with respect to the Earth's
• 23:29
  surface. And when you come back
• 23:32
  you've somehow got to dump that velocity.
• 23:34
  You've got to kill it somehow. Now you know,
• 23:36
  I do remember when I used to read Dundeere,
• 23:39
  the uh, pilot of the future in the Eagle.
• 23:42
  They, they used um, what they called reactor
• 23:45
  rockets. So you had uh, the spacecraft was
• 23:48
  in orbit and then uh, the command that
• 23:52
  Captain Dan Dare said was blower reactors
• 23:55
  and that was forward firing rockets that
• 23:57
  slowed the spacecraft down. And that's what
• 23:59
  they still do. They fire forward
• 24:02
  firing rockets to slow the spacecraft down.
• 24:06
  But unless you've got the same amount of fuel
• 24:08
  as you used to put it up there, you can't use
• 24:11
  that forward firing rocket to gently land it
• 24:14
  on the planet's surface. You've got to have
• 24:16
  something else. And uh, that something else
• 24:18
  is aero braking which is using the atmosphere
• 24:20
  to slow the spacecraft down. That's
• 24:22
  traditionally what has been used. It's the
• 24:25
  only way we have available at the moment
• 24:26
  until somebody invents something that doesn't
• 24:29
  need as much fuel to slow you down as uh, it
• 24:31
  takes you up there.
• 24:33
  Andrew Dunkley: Well that time will probably come. But
• 24:36
  for now making your spacecraft sweat could
• 24:39
  be uh, the new approach. And if you uh,
• 24:42
  are interested in that story, uh, as
• 24:44
  Fred Watson said, it's@space.com.
• 24:49
  okay, we checked all four systems and team
• 24:51
  with a go Space Nats.
• 24:53
  Okay Fred Watson, our final ah, story today
• 24:56
  is a very scary one because um, we
• 24:59
  might not be here next week or maybe it's a
• 25:02
  billion years. I always get the two mixed
• 25:04
  up. Uh, but um, on a serious
• 25:07
  note, uh, some Dutch scientists have come up
• 25:10
  with a new theory as to when the universe
• 25:13
  will end. And it is a
• 25:15
  heck of a lot sooner than we originally
• 25:18
  thought if they are right.
• 25:24
  Professor Fred Watson: Indeed it is. Uh, so here are the numbers,
• 25:26
  okay. Uh, because we might as well start with
• 25:29
  that. We used to think
• 25:33
  that the universe would die
• 25:36
  in 10 to the power 1100
• 25:39
  years. So that is a one with 1100
• 25:41
  zeros after it. It, that's how long we
• 25:43
  thought it would take to die. The
• 25:46
  new calculation uh, is
• 25:49
  only. It's a mere 10 to the power 78
• 25:52
  years. And that's 10
• 25:55
  followed by, sorry one followed by 78
• 25:57
  zeros. Look, that's ah,
• 26:01
  one heck of a difference, isn't it? It's a
• 26:04
  factor of more than 10 different uh,
• 26:07
  uh, it's a factor of more than 10 in
• 26:09
  exponent, which means that it's a very much
• 26:11
  different different. Um, so yes, the
• 26:14
  universe has only got really a brief period
• 26:16
  of 10 to the 78 years to last. Um
• 26:19
  but let's cut to the reason why these
• 26:21
  scientists are ah, uh, making
• 26:24
  these calculations. They're um,
• 26:27
  scientists actually in the Netherlands. Uh,
• 26:29
  and what they've done is they've looked
• 26:32
  at Hawking radiation.
• 26:35
  And that is the, the trick to
• 26:38
  this, this whole calculation. Hawking
• 26:40
  radiation is uh, as we know, the
• 26:43
  rad that leaks from a black hole.
• 26:46
  Uh which is a quantum physics effect because
• 26:49
  uh, relativity says nothing can come out of a
• 26:52
  black hole. But quantum mechanics says well
• 26:53
  they can evaporate very, very slowly.
• 26:56
  And they do. Uh, there's all the
• 26:59
  evidence suggests that Hawking radiation is a
• 27:01
  real thing. And so what these calculations
• 27:04
  are about is how long it takes everything in
• 27:06
  the universe to come to an end by
• 27:08
  Hawking radiation. Um, and they don't just
• 27:11
  cover black holes. They cover everything.
• 27:14
  They cover um, neutron stars which
• 27:17
  are kind of failed black holes. They cover
• 27:19
  white dwarf stars which are kind of failed
• 27:21
  neutron stars. Um, and these all
• 27:24
  have um, a Hawking age. And I
• 27:27
  think actually um, the original calculation
• 27:29
  of 10 to the 1100 years
• 27:33
  was um, um, basically coming from
• 27:36
  just the lifetime of white dwarf stars does,
• 27:39
  but uh, the new calculation
• 27:42
  have uh, have um,
• 27:46
  essentially said uh, the,
• 27:49
  the decay time for white dwarfs is
• 27:53
  uh, sooner than we
• 27:56
  thought. Uh, I think actually the white dwarf
• 27:58
  decay time originally didn't include Hawking
• 28:00
  radiation. I think it was just how long it
• 28:02
  takes to cool down to a completely inert
• 28:05
  object. So um, the new calculation
• 28:07
  takes into account uh, the
• 28:10
  basics of Hawking radiation. Um,
• 28:14
  they've got some nice other
• 28:17
  figures as well because uh,
• 28:21
  they can Work out how long
• 28:23
  neutron stars take to decay. That's 10
• 28:26
  to the power 67 years. Um,
• 28:29
  they can work out how long. Long the
• 28:32
  moon will take to evaporate by human.
• 28:35
  Uh, Sorry, By Hawking radiation.
• 28:38
  And how long it will take a human to
• 28:40
  evaporate. And those figures are
• 28:43
  respectively. Well, they're the same 10 to
• 28:45
  the power 90. So you and I, as we sit here,
• 28:48
  Andrew.
• 28:49
  Andrew Dunkley: Yeah.
• 28:49
  Professor Fred Watson: Uh, we will evaporate in 10 to the power 90
• 28:52
  years, which means we actually outlast the
• 28:55
  universe because the universe is going to
• 28:57
  evaporate in. In 10 to the 78 years.
• 29:01
  Uh, so we're, we're doing well there. How can
• 29:03
  we outlast the universe? I'm not sure what
• 29:06
  the answer to that is.
• 29:08
  Andrew Dunkley: Yeah, well, nothing, um, could. If the
• 29:11
  universe comes to a grinding halt, that's the
• 29:13
  end of everything, isn't it? Ah, to qualify
• 29:16
  this, you've got to accept that, um, they're
• 29:18
  talking about the, the, uh, fading out of
• 29:21
  everything. That's correct. But the universe
• 29:23
  will still be there. It'll just be dead.
• 29:26
  Professor Fred Watson: Unless, uh, the, you know, the
• 29:28
  accelerated expansion of the universe results
• 29:30
  in the Big Rip, which could come a lot sooner
• 29:33
  than those evaporation times. So you're quite
• 29:36
  right. This is assuming nothing else happens
• 29:38
  in the universe. The universe is as boring as
• 29:40
  anything. Uh, and things just
• 29:42
  evaporate by Hawking radiation. That's
• 29:45
  the numbers that you get.
• 29:47
  Andrew Dunkley: Yeah. And there was one other thing we left
• 29:49
  out of that, and that was the, um, um,
• 29:51
  evaporation of brown dwarfs, um, because
• 29:54
  they're failed Disney actors, so
• 29:57
  got to take that into account too. And that
• 29:59
  only takes 88 years.
• 30:01
  Professor Fred Watson: Okay. Very good.
• 30:04
  That's a neat calculation. I think you should
• 30:06
  write. That's up to the conversation, Andrew.
• 30:10
  Andrew Dunkley: It's terrible, Jack. Horrible. Yeah. Um,
• 30:13
  no, but it is, uh, rather fascinating. Um, so
• 30:16
  do we know. I don't know if you said it in
• 30:18
  number of years, what 10 to the 78
• 30:21
  actually means for the universe.
• 30:25
  Professor Fred Watson: Yeah, well, yes, uh, just means one followed
• 30:27
  by 78 zeros. It's a long time.
• 30:30
  Andrew Dunkley: Still a long time.
• 30:32
  Professor Fred Watson: Yeah. And, um, we should be right to.
• 30:34
  Andrew Dunkley: Pay the, the water rates next week then.
• 30:36
  Professor Fred Watson: That's right. I mean, you know, put it in
• 30:38
  perspective. Uh, the Earth is probably going
• 30:41
  to get melted within
• 30:43
  maybe 4 billion years. What's that? 4 times
• 30:46
  10 to 9 years. So. Yeah, yeah, yeah,
• 30:49
  that's, uh. That's. That's
• 30:52
  going to be a much more immediate problem,
• 30:54
  uh, for us than the evaporation of everything
• 30:56
  by Hawking radius.
• 30:57
  Andrew Dunkley: That's assuming humanity has actually
• 30:59
  survived that long, which is totally
• 31:02
  different.
• 31:02
  Professor Fred Watson: Yes, we might.
• 31:03
  Andrew Dunkley: Argument, theory, whatever you like.
• 31:05
  Professor Fred Watson: M yeah.
• 31:06
  Andrew Dunkley: All right. Uh, that story available through
• 31:09
  fizz.org p h y s.org
• 31:12
  if you want to read up on it. It's really,
• 31:14
  really interesting. Uh, and that brings us to
• 31:17
  the end. Fred, thank you very much.
• 31:19
  Professor Fred Watson: Pleasure, Andrew, as always. And we'll speak
• 31:21
  again soon. I'm sure we will.
• 31:23
  Andrew Dunkley: And, uh, looking forward to it. And don't
• 31:25
  forget to visit us online at our website and
• 31:28
  visit the shop while you're there or just
• 31:30
  have a look around. And that's at, uh,
• 31:33
  spacenutspodcast.com or spacenuts
• 31:35
  IO. Uh, I would have said thanks to Huw in
• 31:38
  the studio, but he couldn't be with us today
• 31:40
  because he reached the age of 10 to the 78.
• 31:44
  And that was the end of that from
• 31:46
  me, Andrew Dunkley. Thanks for your company.
• 31:48
  We'll see you on the next episode of Space
• 31:50
  Nuts. Bye. Bye.
• 31:53
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• 31:55
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