Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / Light Pollution Dilemmas, Cosmic Parasol Proposals & Salvaging Space Junk

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Light Pollution Dilemmas, Cosmic Parasol Proposals & Salvaging Space Junk · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Jonti Horner: Hi there.
• 0:00
  Andrew Dunkley: Thanks for joining us on Space Nuts Q and A
• 0:02
  edition. This is where the audience sets the
• 0:04
  agenda, and we answer the questions to the
• 0:06
  best of our ability, which is not much
• 0:08
  ability at all, but we'll do it anyway. Uh,
• 0:11
  coming up, questions about light pollution.
• 0:13
  A, uh, space parasol to protect
• 0:16
  Earth. Interesting. Uh, also salvage
• 0:19
  rights in space and radio waves.
• 0:22
  That's all coming up on space nuts.
• 0:24
  15 seconds. Guidance is internal.
• 0:27
  10, 9, ignition
• 0:30
  sequence. Star nuts. 5, 4,
• 0:33
  3, 2. 1, 2, 3, 4, 5, 5, 4,
• 0:36
  3, 2, 1.
• 0:37
  Jonti Horner: Space nuts.
• 0:38
  Andrew Dunkley: Astronauts report it feels good. And
• 0:41
  he's back again. Professor Jonti Horner,
• 0:43
  professor of Astrophysics at the University
• 0:45
  of Southern Queensland. Jonti. Hi there.
• 0:48
  Jonti Horner: Good afternoon. How are you going?
• 0:49
  Andrew Dunkley: I am well. Want to get
• 0:52
  straight into it?
• 0:53
  Jonti Horner: Yeah, let's dive on in.
• 0:55
  Andrew Dunkley: Okay. Question time. And our, uh, first
• 0:57
  question comes from Mark.
• 1:00
  He says, hello. I have a question about light
• 1:02
  pollution. I live in Connecticut, and the
• 1:05
  light pollution is not as bad as New York
• 1:07
  City, but it is enough. I'm planning a trip
• 1:10
  to Montana this summer just to see the night
• 1:12
  sky. My question is, if I was standing
• 1:15
  in my yard and there was a sudden EMP
• 1:18
  burst and all the electric lights went out,
• 1:20
  how long would it take for me to be able to
• 1:23
  see the night sky in Connecticut as clear and
• 1:26
  as. As beautiful as Point Nemo? I understand
• 1:29
  light speed is fast, but how fast
• 1:32
  would it be to clear the view? I've
• 1:35
  just, uh, recently discovered your podcast. I
• 1:37
  learned something new with each uh, one.
• 1:40
  Uh, please keep up the outstanding work. I
• 1:42
  look forward to every new episode.
• 1:45
  Sincerely, Mark Bookbinder. Thank you,
• 1:47
  Mark. That's a lovely comment. Uh, we don't
• 1:49
  get many nice comments. Everyone's usually
• 1:51
  sticking the knife in. No, I'm not kidding.
• 1:53
  Most people, uh, are terrific. Um,
• 1:56
  although we get the occasional jibe, but that
• 1:58
  goes with the territory. Um,
• 2:01
  yeah, look, I. I had a think about this one,
• 2:04
  and I. I would suggest.
• 2:07
  I don't want to steal your thunder, Jonti,
• 2:09
  because I know you've done your homework, but
• 2:10
  I would suggest that it would be fairly
• 2:12
  instantaneous because the amount of light
• 2:15
  coming down would be the same.
• 2:18
  It's just that it's disturbed by the light
• 2:20
  we're sending up. So when that light we are
• 2:23
  creating suddenly disappeared, surely
• 2:26
  the effect would be an instant
• 2:29
  view of what's really happening up there.
• 2:32
  Jonti Horner: Effectively, I think that's pretty much it.
• 2:34
  Um, uh, now, there's a few
• 2:37
  things that fall into that, and that's a
• 2:38
  really good kind of executive summary type
• 2:41
  level. So the reason that Light pollution is
• 2:43
  a problem for you. Seeing the night sky and
• 2:45
  all its wonder is you're basically increasing
• 2:48
  the brightness of the whole sky by an
• 2:50
  artificial amount which washes out the
• 2:52
  fine detail of the darker, the fainter stuff.
• 2:55
  So the brighter your light pollution levels
• 2:57
  are, uh, the brighter the sky is and so the
• 2:59
  fewer faint objects you can see and the more
• 3:01
  you brighten that, the less you'll see. If
• 3:03
  you turn all the lights off at once, the sky
• 3:06
  will almost instantaneously become as dark
• 3:09
  as it could possibly be. And then what's
• 3:12
  working against you is the adaptation of your
• 3:14
  eye. So we have this thing called dark
• 3:17
  adaptation and m, it's how our eye
• 3:20
  adjusts and responds to low light levels to
• 3:22
  allow us to function in those levels
• 3:24
  effectively. And you get the bulk of
• 3:27
  your dark adaption within about the first
• 3:29
  five minutes. But your eyes continue
• 3:32
  adapting and getting better and better at
• 3:34
  seeing in the dark over about
• 3:37
  45 minute period. So you have to be out under
• 3:40
  the night sky and avoid looking at any
• 3:42
  sources of bright light for about 45
• 3:44
  minutes before you're as adapted as you can
• 3:46
  be and you can get the best possible view you
• 3:49
  can get. Now what would happen is if you
• 3:52
  were out and about in your sadly light
• 3:54
  polluted skies in Connecticut, um,
• 3:57
  you are um, not very well dark adapted
• 3:59
  because the sky is very bright. So your clock
• 4:02
  would have to start ticking from the point
• 4:04
  the lights went out. So I would hope that the
• 4:05
  lights stared out for at least an hour for
• 4:07
  you to give you the best possible view. But
• 4:10
  even then you might not get the best view of
• 4:12
  the night sky you could anywhere on Earth,
• 4:13
  because you then run into the issues of the
• 4:15
  Earth's atmosphere. Um, now I
• 4:18
  regularly go out to the wonderful Lady
• 4:20
  Elliott island on the Barrier Reef where
• 4:22
  there's effectively no light pollution at all
• 4:24
  and the sky is dark enough that for example,
• 4:26
  I can see the Triangulum galaxy, which is
• 4:29
  fainter than Andromeda. I can see pretty much
• 4:31
  every time I go out there there's a darker
• 4:33
  light and um, I lead guessing
• 4:36
  some stargazing there and m tell them how
• 4:38
  awesome the sky is. But I make the point that
• 4:40
  if they were to go to the centre of
• 4:41
  Australia, to somewhere like Uluru or out
• 4:44
  into the Nullarborg Desert, they'd actually
• 4:46
  see a better sky there than we see at Lady
• 4:49
  Elliot. Because at Lady Elliot you have a
• 4:51
  limitation that you're surrounded by very
• 4:52
  humid, very turbulent air because of the
• 4:55
  energy from the ocean stirring the air up.
• 4:57
  And so different locations on the Earth offer
• 5:00
  different clarity of the night sky.
• 5:03
  So what I'd suggest is from Connecticut,
• 5:06
  I've got the light pollution map up here,
• 5:08
  which, um, is light pollutionmap.info for
• 5:10
  people who want to look and weep at how bad
• 5:12
  the skies are from their location and plan
• 5:15
  their dark sky holidays. That's a really nice
• 5:17
  little website. You're relatively coastal
• 5:20
  and so therefore your air is going to be
• 5:21
  quite humid and turbulent. And I would
• 5:23
  suggest if you turned, turned all the lights
• 5:25
  on the earth off, that you would have an
• 5:28
  experience probably comparable to what we get
• 5:31
  in coastal Australia. Whereas if you went
• 5:33
  deep into the inland and you got a really
• 5:35
  dark sky and be better if you then went
• 5:38
  to higher ground, like perhaps in Arizona,
• 5:40
  which I understand is a quite high altitude
• 5:43
  desert. If you're at higher altitude
• 5:46
  there is less air, so therefore there is
• 5:49
  less muck and you get a better sky. But
• 5:52
  that's balanced by the fact that if you're at
• 5:53
  high enough altitude, you're not getting as
• 5:55
  much oxygen and you don't see as effectively.
• 5:57
  So I've had stories from colleagues of mine
• 5:59
  who've been up to the great observatories,
• 6:02
  um, in the Andes, in Chile and also up
• 6:05
  in Hawaii who've gone out on a night and
• 6:07
  they've initially been quite disappointed
• 6:08
  that they didn't see a sky quite as
• 6:10
  expensive, as spectacular as they thought
• 6:12
  they would do. And people on Hawaii actually
• 6:14
  will often have a little bowl of oxygen and
• 6:16
  have an inhale to increase their blood oxygen
• 6:19
  levels, to increase the response of their
• 6:21
  eyes to counter the thinner atmosphere and
• 6:24
  then they get a really spectacular view.
• 6:26
  Andrew Dunkley: Wow.
• 6:27
  Jonti Horner: So, like most questions, there's a very
• 6:29
  simple answer which is as soon as the light
• 6:31
  goes out, you'll get a really good view, but
• 6:34
  that view will get better as your eyes adjust
• 6:36
  to the darkness. But how good of you you get
• 6:39
  is not just dependent on the light pollution,
• 6:41
  you'll start to bring in other effects. And
• 6:42
  my hope would be that the EMP burst and the
• 6:45
  end of all street lighting would happen at
• 6:47
  new moon rather than full moon. Because if
• 6:50
  you've got a full moon in the sky, all those
• 6:52
  effects of humidity and dust are exacerbated.
• 6:55
  And even with all the lights turned off, the
• 6:57
  night sky at full moon is a bit
• 6:58
  disappointing. You know, if I could do one
• 7:00
  astronomical thing as a kind of great
• 7:01
  celestial dictator, I get rid of the moon.
• 7:04
  It's just a pen in the backside. It's always
• 7:05
  in the way when I want to take photos and
• 7:07
  stops me seeing the more interesting things.
• 7:09
  It's like um, or lock it into a kind of one
• 7:12
  to one orbit with the Earth's orbit around
• 7:14
  the sun. So we only ever see it as a very
• 7:16
  thin crescent. So it can be beautiful in the
• 7:18
  early evening, then bugger off so I can see
• 7:20
  the prettier things.
• 7:21
  Andrew Dunkley: I can tell you why that's a problem. It's
• 7:23
  because everybody likes mooning in photos.
• 7:26
  Jonti Horner: Oh, totally.
• 7:29
  Andrew Dunkley: Uh, dear. Uh, um,
• 7:32
  um, I just thought about the
• 7:35
  physical effect of the light being
• 7:38
  turned off. But yeah, I didn't consider the
• 7:40
  atmosphere or the location or,
• 7:43
  um, or your eyes adjusting. I just had
• 7:46
  a look at that light pollution map website
• 7:48
  and I've honed in on Duo where I am
• 7:51
  now. If I just look at the nearest
• 7:54
  towns, yeah, I'd have to go just a bit over
• 7:57
  20km out of town to get to a
• 8:00
  dark sky area which is not too bad. But if,
• 8:02
  if you're in Sydney, forget it.
• 8:05
  You're gonna have to drive a few hours.
• 8:07
  Jonti Horner: But do yourself a favor and zoom out and then
• 8:10
  look at the eastern half of the US or look at
• 8:13
  eastern Asia and you'll see why we are so.
• 8:15
  Let's go. Yeah. That's why
• 8:18
  astro tourism's such a growing thing for us
• 8:21
  here in Australia. Because even in the big
• 8:23
  cities, you know, I moved to Sydney in 2010
• 8:26
  and lived very briefly in a
• 8:29
  hotel right in the center of Sydney, the most
• 8:31
  light polluted part. But I could still see
• 8:34
  the Milky Way from the roof of the hotel
• 8:37
  because our skies are so good. There's a
• 8:38
  couple of factors there. One is that, uh,
• 8:40
  Sydney itself puts out a lot of light, but
• 8:42
  there's not much else around. So if you're
• 8:44
  looking away from Sydney over towards the
• 8:46
  ocean, you're looking towards darker skies.
• 8:48
  So that helps. But the other thing is, and
• 8:51
  this ties into why we get sunburnt so easily
• 8:53
  in Australia, the air is just clearer.
• 8:56
  So I moved to Australia and everybody said,
• 8:58
  you're going to get burnt by the sun and it's
• 8:59
  awful. And my first thought was that's the
• 9:02
  ozone hole. Because I thought Australia was
• 9:04
  further south because I'm used to our
• 9:06
  corrupted maps that show the southern
• 9:09
  hemisphere wrong. And so Australia looks like
• 9:10
  it's near Antarctica and Australia is
• 9:12
  actually near the equator. It's. Yeah, it is.
• 9:14
  So it's not the ozone hole at all. But I told
• 9:16
  some people it's actually due to the fact
• 9:18
  that the air in Australia has a much lower
• 9:21
  amount of particulates in than any other
• 9:23
  continent to do with what's on the interior
• 9:26
  of the continent to do with the fact there's
• 9:27
  less pollution. So that means there's less to
• 9:29
  scatter the solar uv, which is why we get
• 9:32
  higher UV indices and therefore more sunburn.
• 9:34
  Um, so it's a quirk of geography rather than
• 9:37
  just lots of clear skies, which mean we get
• 9:39
  UV indices up to 13 or 14 on a hot
• 9:42
  summer's day and basically you fry to a crisp
• 9:45
  very, very quickly.
• 9:46
  What that means for astronomy though is that,
• 9:48
  uh, for a given place with a given, given
• 9:50
  amount of lighting, we actually get a better
• 9:53
  sky than we would do in other places because
• 9:55
  there's less to scatter that light. So that
• 9:58
  same amount of lighting has a slightly lower
• 10:00
  impact. Um, one of the story that ties into
• 10:02
  this that I always remember one of the big
• 10:04
  hurricanes probably 20 or 30 years ago
• 10:06
  knocked out the power across great swathes
• 10:09
  of, I think it was Florida. And many people
• 10:11
  saw the Milky Way for the very first time in
• 10:13
  their lives. And there was panic. People were
• 10:15
  actually calling up, uh, their local police.
• 10:17
  Oh, I remember this because they thought that
• 10:20
  the aliens were coming because the sky looked
• 10:22
  so weird and unusual because there were all
• 10:23
  these bright points of light in it and this
• 10:25
  weird milky glow going across the sky and ah,
• 10:28
  we laugh. But it tells you just how decoupled
• 10:31
  people are from something that's been so
• 10:33
  wonderfully culturally significant for all of
• 10:35
  our history. It's so important to the
• 10:37
  traditional owners of the land here in
• 10:38
  Australia, but also all around the world who
• 10:41
  have this deep and intimate connection to the
• 10:42
  night sky. And an event like that
• 10:46
  really drills home the damage we've done and
• 10:48
  how we've removed this. And I'm always
• 10:51
  amazed at the reluctance of people in kind of
• 10:53
  groups on social media to accept that light
• 10:55
  pollution is a problem because can lay odds
• 10:58
  at the same problem who say, don't be grumpy,
• 10:59
  we need our lights at night to see would be
• 11:02
  really, really unpleasantly happy if we have
• 11:05
  the same level of noise pollution. If they
• 11:07
  had their neighbors kicking out AC DC at 1am
• 11:09
  in the morning, they'd be kicking off to the
• 11:12
  council. And it seems that we view light
• 11:14
  pollution a lot less seriously than we view
• 11:17
  sound pollution or other forms of pollution.
• 11:19
  And that's changing a bit. But
• 11:22
  there's also an energy source side of it, I
• 11:24
  mean this is a bit that always makes my head
• 11:25
  hurt is if you're throwing 30% of your light
• 11:27
  up into the sky, you're wasting 30% of your
• 11:30
  electricity and you're therefore just burning
• 11:32
  money. And yeah, I'm sure the energy
• 11:35
  companies love that because they get bigger
• 11:36
  profits. But doesn't seem a very efficient
• 11:39
  way to do things.
• 11:40
  Andrew Dunkley: No. And when you look at the map, uh, Eastern
• 11:42
  United States, basically all the United
• 11:44
  States, but particularly the eastern half.
• 11:46
  Western Europe, uh, East Asia,
• 11:49
  um, and even the east, uh, eastern
• 11:52
  half of South America pretty well just
• 11:55
  light pollution. Central. Yeah. But you look
• 11:58
  at Australia and um,
• 12:00
  parts of North Africa, uh,
• 12:03
  Greenland, although it's an ice cap so it
• 12:05
  makes it a bit difficult. But uh, even the
• 12:07
  um, uh, big areas around Russia
• 12:10
  and Siberia, uh, complete darkness.
• 12:13
  Which is, you know, very good
• 12:16
  place to, to go if you. Well probably not
• 12:18
  Russia at the moment but um, good places to
• 12:21
  go to look at the sky and in terms of air
• 12:23
  quality. Um, they did a test a few years ago
• 12:26
  and found that the most pure air in the world
• 12:28
  crosses Tasmania and southern
• 12:31
  Australia.
• 12:33
  Jonti Horner: Which sounds about right. But it is why there
• 12:34
  is a growing interest in astro tourism
• 12:37
  in Australia. I've spoken to a few people
• 12:39
  about this in the last 12 months where local
• 12:42
  councils and
• 12:45
  different commercial groups are looking at
• 12:47
  adding astronomy activities to their
• 12:49
  offerings because they're aware that for
• 12:52
  people coming in from a lot of our places,
• 12:55
  um, that source tourists to Australia. These
• 12:57
  are people who've never seen the Milky Way,
• 12:58
  who've never seen the night sky properly. And
• 13:01
  to them it's this kind of romantic ideal that
• 13:03
  they could have a night lying under the stars
• 13:06
  and see the Milky Way above them. And that's
• 13:09
  just the reality here. You know, I step
• 13:10
  outside in my backyard and I see the Milky
• 13:12
  Way and that makes it a really big
• 13:15
  tourist drawer. And people are cottoning onto
• 13:17
  that. And that will then be extra ammunition
• 13:19
  for us improving lighting laws in Australia.
• 13:21
  Because there's an interest beyond just
• 13:23
  astronomers. There's a commercial interest to
• 13:25
  drive that. So I think it's a real positive
• 13:27
  thing. And um, yeah, we'll see more of it.
• 13:29
  But in the meantime, roll on the EMP purse.
• 13:33
  Andrew Dunkley: Yes, indeed. Uh, thanks for the question
• 13:35
  mark. See what you've done. Good, uh, to hear
• 13:37
  from.
• 13:40
  Jonti Horner: Roger. Your lab is right here.
• 13:42
  Andrew Dunkley: Also Space Nuts. This is Space Nuts with
• 13:44
  Andrew Dunkley and Jonti Horner.
• 13:46
  Our next question comes from
• 13:48
  Doug. It's an audio question.
• 13:50
  Speaker C: Hi Space Nuts, it's Doug and Hazel the
• 13:52
  Wonderdoodle calling again. Thank you for
• 13:55
  your responses to my previous questions.
• 13:58
  My question this time is about
• 14:00
  uh, blocking sunlight. Given that
• 14:03
  we as humanity have no ability to
• 14:06
  control our carbon emissions, it seems.
• 14:09
  Um, the next question is to me,
• 14:12
  uh, is geoengineering possible?
• 14:15
  Now, given that, uh, seed
• 14:18
  in the higher atmosphere with reflective
• 14:20
  particles would probably not go over too well
• 14:23
  with the, uh, chemtrails people.
• 14:26
  I'm going to suggest that, uh, putting
• 14:29
  some sort of sun blocker out at Lagrange
• 14:32
  point one, uh, would be
• 14:35
  a solution that would probably need to be
• 14:38
  investigated. Um, ChatGPT
• 14:40
  suggested that a 3 million square
• 14:43
  meter parasol, for lack of a better word,
• 14:46
  would block 1% of the sun's light
• 14:49
  hitting the Earth. Don't, um, know what the
• 14:51
  magic number is. Don't know if we should even
• 14:53
  do this. But the question I have is
• 14:56
  does anybody know about anybody working on
• 14:59
  this particular program right now
• 15:02
  as uh, a contingency? Thanks very much.
• 15:06
  Have a good day.
• 15:07
  Andrew Dunkley: You too, Doug. Thank you. And hello to Hazel
• 15:09
  the Wonder Doodle. Uh, this has come
• 15:12
  up before and I do think somebody has been
• 15:14
  looking into the possibility of putting a
• 15:17
  parasol in space to try and uh,
• 15:19
  shade Earth. Um, I
• 15:22
  just don't know how well it would work.
• 15:25
  Jonti Horner: It's a challenge. I mean it, it, the reason
• 15:28
  I'm chuckling a little bit in the background
• 15:29
  here is not actually about this idea, which I
• 15:31
  think is a good one. It's hazel the wind area
• 15:33
  as well, isn't it?
• 15:34
  Andrew Dunkley: That's what's making you chuckle.
• 15:35
  Jonti Horner: It's not even Hazel the Wonder Doodle. It
• 15:37
  just amuses me that on the one hand we're
• 15:39
  talking here about building parasols to
• 15:41
  shield the sun from the daytime sky, while at
• 15:43
  the same time a few weeks ago we talked about
• 15:45
  a group of idiots with a startup in
• 15:47
  California to reflect the sun to shine it on
• 15:49
  the night times. And I've got visions of
• 15:51
  the fact that you get these wonderful geo
• 15:53
  engineers deliberately shielding blocking
• 15:56
  sunlight from the daylight sky only to have
• 15:58
  their work undone by a group of equally
• 15:59
  stupid people shining, um, lights on the
• 16:02
  nighttime sky to just basically make the
• 16:04
  nights hotter and offset all of the good
• 16:06
  work. Um, but that's more me chuckling at the
• 16:08
  idiocy of reflector orbital than it is about
• 16:10
  this question. Because this is actually a
• 16:12
  really good question, Doug. It is
• 16:14
  abundantly clear, um, that.
• 16:17
  Okay, don't mind me. I just got a weird pop
• 16:19
  up saying I'm going to expire
• 16:22
  after 150 minutes of inactivity, which is
• 16:24
  never good. But I don't think that's to do
• 16:25
  with space nuts. So I've just moved my mouse
• 16:27
  and all is good. So I am not going wake spire
• 16:30
  live on air. This is good. Yeah.
• 16:32
  So there is fundamentally an issue that the
• 16:35
  planet is warming and the planet is warming
• 16:37
  because of human activities. And that is
• 16:41
  not open, uh, for dispute really anymore. I
• 16:43
  know that there are a variety of opinions
• 16:44
  available on this, but for me as an
• 16:46
  astronomer, the evidence is utterly
• 16:48
  overwhelming. And the only thing that can
• 16:51
  explain the changes that we're seeing, not
• 16:53
  the size of the changes, but the speed of the
• 16:55
  changes, is human activity. No
• 16:57
  physical process, other than perhaps a
• 17:00
  rock hitting the Earth and killing everybody,
• 17:03
  um, like the dinosaur level extinction, there
• 17:05
  is nothing else that could cause this rate of
• 17:07
  change. So it's very, very clear that human
• 17:10
  activity is the cause of this and, um, that
• 17:13
  there is some inertia in trying to persuade
• 17:14
  humans to stop doing the things that cause
• 17:16
  the problems and understand that. So there's
• 17:18
  a growing list of suggestions of ways that we
• 17:21
  could mitigate for climate change out there.
• 17:24
  One, as Doug said, is sprinkling reflective
• 17:26
  particles into the upper atmosphere to
• 17:28
  effectively increase the Earth's albedo, uh,
• 17:31
  which would mean more energy was reflected to
• 17:33
  space and less makes it down to the surface
• 17:35
  of the Earth to kind of heat the pressure
• 17:37
  cooker. And that could
• 17:40
  possibly work. It'll be interesting to see
• 17:42
  what role SpaceX plays in that in the years
• 17:44
  to come, because with all of the satellites
• 17:47
  they're launching, there's a growing, um,
• 17:50
  number of things returning to Earth and
• 17:51
  burning up in the upper atmosphere that are
• 17:53
  depositing metals like aluminum into the
• 17:56
  upper atmosphere. And nobody's really sure
• 17:58
  what's going to happen there. So that might
• 18:00
  actually inadvertently do exactly what Doug
• 18:02
  mentioned and increase the Earth's albedo
• 18:05
  and offset some climate change, or it might
• 18:08
  make it worse. People are still trying to
• 18:09
  figure out what's going to happen there. And
• 18:11
  that ties into the idea that space is still a
• 18:13
  little bit of the wild, Wild west, in that
• 18:16
  things are happening faster than legislation
• 18:19
  can adapt. You know, we've got tons of
• 18:21
  aluminium being added to the atmosphere and
• 18:23
  we don't know what it's going to do, but that
• 18:25
  might have part of this effect. But an
• 18:27
  obvious way that you could cool the Earth is
• 18:30
  by blocking some sunlight. Fundamentally,
• 18:33
  that makes sense. If you block 1% of the
• 18:35
  sun's light, you block 1% of the energy
• 18:37
  coming into the Earth, which will be about
• 18:39
  13.6 watts. The solar constant's about
• 18:41
  1360 watts per square meter. Block, uh,
• 18:44
  1% of that, that will be 13.6 watts,
• 18:47
  and that will be more than enough to offset
• 18:49
  climate change and probably more so. But
• 18:52
  let's say we wanted to block 1% of the light
• 18:54
  from the sun. That means you would need a
• 18:56
  parasol that is equal to 1% of the
• 18:59
  cross section of the Earth, Uh, if that
• 19:01
  parasol blocked all of the light from the sun
• 19:03
  that was hitting it. So that means
• 19:06
  1% of the Earth's surface would be dark. The
• 19:08
  sun wouldn't be falling on it. Or you diffuse
• 19:11
  that, and, um, you have 1% less light coming
• 19:14
  down. So if you do the maths of that. The
• 19:16
  Earth has a radius
• 19:19
  of about 6,378
• 19:22
  kilometers. That varies because the Earth's a
• 19:24
  bit ablate. So the radius from pole to pole
• 19:27
  is different to the radius across the
• 19:29
  equator. But we can use that as a mean
• 19:31
  radius. That means that the Earth, uh, has a
• 19:34
  surface area of about 10, 1.9,
• 19:37
  I think it was, times 10 to the 14
• 19:40
  meters squared. So to
• 19:43
  block 1% of the light, you'd need a
• 19:46
  parasol. That is 1% of that. So that would be
• 19:49
  about 1, um, point 28 times 10 to
• 19:51
  the 12 meters squared. Which means
• 19:54
  that you will need a parasol. I'm sorry,
• 19:57
  kilometers squared. I've done this
• 19:58
  calculation in kilometers, um, which would.
• 20:01
  No, that is in meters, sorry. Which would
• 20:03
  mean you'd need a parasol if you made it
• 20:06
  Square. That is
• 20:08
  1130 kilometers on a
• 20:10
  side
• 20:13
  that I think is technologically beyond us at
• 20:16
  the minute. Um, added to which,
• 20:19
  you know that the politicians would want us
• 20:21
  to mine that material on Earth and launch it
• 20:23
  because that would be more profitable. So the
• 20:25
  process of mining and launching all that
• 20:26
  material to build 1,000 kilometers on each
• 20:29
  side. Parasol Will probably put far more
• 20:32
  greenhouse gases into the atmosphere and
• 20:34
  exacerbate the problem. The other challenge
• 20:36
  you'd have with the parasol issue, though, is
• 20:38
  that the L1 point, which would be the obvious
• 20:40
  place to put it, that's a point between the
• 20:43
  Earth and the Sun. Where an object would
• 20:45
  rotate at the same orbital period as the
• 20:47
  Earth. And, um, be in this kind of semi
• 20:49
  stable location. That's where a lot of our
• 20:51
  solar observation spacecraft go, like soho,
• 20:53
  to give us early warning of space weather.
• 20:56
  Now, the L1 point is about 1.5 million
• 20:59
  kilometers away. Things at
• 21:01
  L1 are not fully stable. So they need rockets
• 21:04
  and actuators to keep them on point. Because
• 21:05
  if they drift too far away, they'll fall out
• 21:08
  of the stable area and go off orbiting the
• 21:10
  sun on the rock. So what you need to do is
• 21:13
  have an object 1,000 kilometers on each
• 21:16
  side. Located one and a half million
• 21:18
  kilometers away. That could be positioned
• 21:21
  accurately enough that the shadow it casts
• 21:23
  hits a target 6,300 km
• 21:26
  in radius rather than missing us. So as it
• 21:29
  drifts around, we'd have to keep it on point
• 21:31
  to an accuracy of just a few hundred
• 21:33
  kilometers. And so this is one of those
• 21:36
  things where it's a fabulous idea for science
• 21:38
  fiction and it is the kind of thing where we
• 21:40
  can imagine all of the steps we need to take
• 21:42
  to make it work. So it's within the bounds of
• 21:44
  our technology in terms of our ability to
• 21:47
  make stuff, but it's the scale of it that
• 21:50
  makes it impractical. And that's why a
• 21:53
  lot of these ideas of parasols
• 21:56
  fall down, is that the amount of area
• 21:59
  you'd have to cover to block enough light to
• 22:01
  make it feasible are so huge that it's just
• 22:03
  technologically the building of them and the
• 22:06
  keeping them on point will be too much of a
• 22:08
  challenge. It be a global endeavor that would
• 22:10
  make the efforts for the Apollo missions seem
• 22:13
  like tiny little small fry in comparison.
• 22:16
  I don't know if anybody's ever done a
• 22:18
  calculation of the cost that this would have.
• 22:22
  Um, but I suspect there are other
• 22:23
  geoengineering ideas that will be more
• 22:26
  financially feasible. Uh,
• 22:29
  I'm always an optimist. I mean, I am very
• 22:31
  worried, like everybody is, about climate
• 22:32
  change. I have been since I was a kid. I've
• 22:35
  lived in places where it is writ large on
• 22:38
  the landscape. I always talk about when I
• 22:39
  lived in Switzerland, and they've got
• 22:41
  photographs from mid summer, uh, in all these
• 22:43
  little Alpine villages of the glacier just
• 22:45
  behind the village. Evening, midsummer. And
• 22:47
  then you step outside and you can't see the
• 22:49
  glacier because it's retreated so far up the
• 22:51
  mountains it's no longer in view. So I've
• 22:53
  lived in places where it's obvious. But I'm
• 22:56
  always of the idea that eventually human
• 22:58
  ingenuity and commercial, um,
• 23:01
  interests will get to the point where it is
• 23:04
  something we'll solve. And I think we're
• 23:06
  seeing that a bit now with electric cars.
• 23:07
  We've had the technology to have electric
• 23:10
  vehicles for more than 100 years. I remember
• 23:12
  getting milk delivered by the milkman as a
• 23:14
  kid. And, uh, they were going around in
• 23:16
  electric milk carts, you know, so we have
• 23:18
  that technology even then. But for a long
• 23:21
  time nobody's had electric cars, nobody's
• 23:22
  considered it solvable. But eventually the
• 23:25
  costs have dropped enough that they're a
• 23:26
  viable alternative and now people are taking
• 23:28
  them up. So you're seeing a drop in the
• 23:30
  number of petrol vehicles. And I'd like to
• 23:32
  think that because a lot of the things that
• 23:35
  we do to cause climate change are
• 23:37
  fundamentally inefficient, as our technology
• 23:39
  improves, we'll move to much more
• 23:42
  efficient processes that generate less of the
• 23:44
  things that cause climate change. And, uh, we
• 23:46
  will find a solution. But the problem is the
• 23:48
  lag time is such that the longer we wait, the
• 23:50
  worse it's going to get before it gets better
• 23:52
  again. And there are some suggestions that,
• 23:54
  for example, the horrendous hurricane that
• 23:57
  hit Jamaica last week was significantly
• 24:00
  worse because of the effect of climate change
• 24:02
  on the temperatures of the water. There's now
• 24:03
  actually a whole branch of mathematical
• 24:06
  science that delves into
• 24:09
  calculating not a yes, no did climate change
• 24:12
  cause this event, but rather a statistical
• 24:15
  analysis of how much worse was this
• 24:18
  event as a result of the effects of climate
• 24:20
  change. And I think the numbers for that
• 24:22
  hurricane last week were quite startling
• 24:25
  that it was made noticeably worse because of
• 24:28
  the increased heating of the ocean and all
• 24:30
  the rest of it. Yeah, it is a real problem
• 24:32
  with. We want to get solutions, but I think
• 24:34
  the parasol is a bit too hard.
• 24:36
  Andrew Dunkley: Yeah, I did read the science behind why that
• 24:38
  storm was so severe and it was quite an
• 24:40
  interesting read. And I won't go into it now
• 24:42
  because I probably get half of it wrong.
• 24:44
  But, um, you might also be interested,
• 24:47
  Doug, to know that there have been some
• 24:49
  researchers looking into this. Not just
• 24:53
  maybe a single object in space to,
• 24:56
  to block the sun. But University, uh, of
• 24:59
  Arizona was looking at a, uh, cloud of small
• 25:02
  spacecraft. Uh, there was another research,
• 25:05
  uh, effort at mit, uh,
• 25:08
  looking at inflatable space bubbles. Uh,
• 25:10
  another idea out of the University of Hawaii,
• 25:13
  um, tethering shades to an asteroid. The
• 25:16
  asteroid being used as a counterweight if
• 25:18
  they could capture one. That's another
• 25:20
  impossible dream at the moment. Solar sails
• 25:22
  and lightweight films and, and even one,
• 25:25
  uh, proposed only a couple of years ago was,
• 25:27
  um, to start ejecting lunar
• 25:30
  dust into space to create
• 25:33
  a dust cloud to block the sun. M.
• 25:36
  My worry is if we do decide
• 25:39
  that that's the solution and we do it and
• 25:41
  then we solve the problem of global warming,
• 25:45
  won't we then put ourselves in a position
• 25:47
  where we could cause, uh, a global
• 25:50
  winter?
• 25:51
  Jonti Horner: Um.
• 25:54
  Andrew Dunkley: Even if we reach a point where we've got the
• 25:56
  technology to solve the problem, as
• 25:59
  Doug said, should we do it?
• 26:01
  Jonti Horner: And we also come to
• 26:04
  really interesting questions because
• 26:07
  underlying the climate change we've got, um,
• 26:10
  there's also the fact that the Earth's, uh,
• 26:12
  climate changes naturally on much longer
• 26:14
  timescales. We get the glacial and
• 26:15
  interglacial periods. So if we ever do get to
• 26:18
  the point where we've got climate control,
• 26:20
  so. So in other words, we can set the Earth's
• 26:23
  climate to be. At a certain point we can fix
• 26:25
  a problem. And if we can fix a problem, we
• 26:27
  can then say where we want the climate to
• 26:29
  sit. What do we choose? Do we allow
• 26:32
  that very slow pace of climate change to
• 26:34
  happen? Do we figure out the conditions that
• 26:36
  are optimal and set it there? There's
• 26:39
  a lot of really interesting stuff that would
• 26:41
  feed into science fiction rather than science
• 26:42
  fact that come from the fact that if you've
• 26:44
  got to the point where you can solve the
• 26:45
  problem, you've got to the point where you
• 26:47
  can geoengineer the Earth's climate to suit.
• 26:50
  So where do you therefore set the sweet spot?
• 26:52
  Do you set it at uh, the year 2000 mean, the
• 26:55
  1900 mean? Do you make it a little bit
• 26:58
  cooler than that? Do you make it a little bit
• 26:59
  warmer than that? It's a really interesting
• 27:01
  one. Which for an incredibly complex and
• 27:04
  chaotic system, um, would lead to a lot of
• 27:06
  implications about weather disasters and all
• 27:09
  the rest of it. Yeah, there's a lot of
• 27:11
  interesting stuff there. I think it's going
• 27:12
  to be interesting times for the next hundred
• 27:14
  or two hundred years as humanity tries to
• 27:16
  solve the problems it's made.
• 27:18
  Andrew Dunkley: Indeed. Yes. Thank you Doug, Great to hear
• 27:21
  from you. Keep them coming. There's some
• 27:23
  terrific ideas out there that uh, people want
• 27:25
  to learn more about. And this is
• 27:28
  Space Nuts with Andrew Dunkley and Jonti
• 27:31
  Horner.
• 27:36
  Space Nuts.
• 27:37
  Our next question, uh, comes from another
• 27:40
  YouTuber. Uh, and
• 27:42
  uh, the question is who has the salvage
• 27:45
  rights on all the scrap satellites and is
• 27:48
  there a plan or a uh, map of all the
• 27:51
  defunct scrap in orbit? Possibly in the
• 27:54
  future there would be good business in
• 27:56
  recovering all the precious metals, et
• 27:58
  cetera. It's a good question. I know they
• 28:00
  were experimenting with different ways of
• 28:02
  bringing down defunct satellites, uh,
• 28:06
  and all they were doing was like testing
• 28:08
  harpoons and things like that or whatever to
• 28:11
  make them re enter and burn up. But this is,
• 28:14
  this is um, a whole new ball game. Salvage.
• 28:17
  Uh, I don't, I haven't heard of it.
• 28:19
  Jonti Horner: Have you? It's yet
• 28:22
  another area where legislation is not keeping
• 28:25
  up with use. So there's a
• 28:28
  lot of challenges with this. Space is vastly
• 28:30
  big and um, the things we put up there are
• 28:32
  very small compared to the size of the space
• 28:34
  that's up there. There are a lot of efforts
• 28:37
  going on to map and to keep track of all of
• 28:39
  the bits of debris, both large scale like
• 28:42
  satellites and former rocket bodies, down to
• 28:44
  the very small fragments you've got out
• 28:46
  there. And that's the whole Area of space,
• 28:48
  situational awareness. There's telescopes
• 28:50
  around the world tracking debris, keeping it
• 28:52
  in databases. And the thing there is
• 28:55
  that you can't just assume that once you've
• 28:57
  seen it, you know what it's orbit is and
• 28:58
  you'll know where it is forevermore, because
• 29:00
  it's a complex environment where the Earth's
• 29:02
  atmosphere is breathing in and out, getting
• 29:04
  bigger and smaller, and the solar wind is
• 29:06
  varying. And all these things that happen,
• 29:08
  even down to the subtleties of the varying
• 29:11
  densities of different parts of the Earth's
• 29:13
  surface, causing slight changes in the
• 29:15
  Earth's gravity at, uh, the kind of level you
• 29:17
  want to track these things, all of that means
• 29:19
  that you need to keep tracking them. You
• 29:21
  can't just find them once and say it's there
• 29:22
  and that's it. So there's a whole burgeoning
• 29:25
  kind of research industry built around
• 29:27
  tracking this debris, using laser range
• 29:29
  finding to get as accurate a position as
• 29:31
  possible. And part of the reason for that is
• 29:34
  so that things like expensive satellites and
• 29:36
  the space station can dodge when there's a
• 29:38
  chance of an impact. That's always helpful.
• 29:41
  Um, it is also just so that we were aware of
• 29:43
  what's up there, and it's a problem that's
• 29:44
  only going to get worse. Now, I did a little
• 29:46
  bit of searching around because I had never
• 29:49
  thought of the salvage of
• 29:52
  satellites and stuff like that as being a
• 29:55
  thing. Now, in maritime
• 29:58
  law, there's this concept of the right to
• 30:00
  salvage, which is when something is becoming
• 30:02
  dangerous or when it's out, which allows
• 30:05
  people to claim salvage rights. There is no
• 30:07
  such thing in space. I found a few articles
• 30:09
  that all confirm that. And I quote from an
• 30:12
  article in the spacereview.com, there is no
• 30:15
  right of salvage analogous to the right found
• 30:17
  in maritime law. Which means that even though
• 30:19
  a satellite or some other space object may
• 30:21
  not be functioning, that does not imply that
• 30:24
  it has been abandoned by the nation that
• 30:26
  launched it. And there's a pretty lengthy
• 30:29
  spiel following that which basically says, if
• 30:31
  you don't have concept for the nation that
• 30:32
  launched and operated that thing, you're not
• 30:35
  allowed to dispose of it or interfere with
• 30:37
  it.
• 30:38
  Andrew Dunkley: In fact, uh, I might just add a caveat to
• 30:41
  that. Uh, if you launch something into space,
• 30:43
  it is your responsibility.
• 30:45
  Jonti Horner: Yes, absolutely. Which follows on to the
• 30:48
  next point. That's the issue about salvaging
• 30:50
  it while it is still in space. And, um, I
• 30:53
  could imagine that with sufficiently future
• 30:56
  technology and a more crowded environment
• 30:58
  around space, there could be a commercial
• 31:00
  opportunity for somebody to develop Yeah, a
• 31:02
  cleanup crew, which companies
• 31:05
  who own a satellite can pay to
• 31:08
  recover their satellite and dispose of it
• 31:09
  safely or to give harvesting rights or
• 31:12
  whatever, where that's dealt with. I could
• 31:14
  see that as a commercial thing down the line.
• 31:16
  But it also has an impact on what happens
• 31:18
  when satellites fall back to Earth. Should
• 31:21
  they make it through the Earth's atmosphere
• 31:23
  intact and make it to the surface of the
• 31:25
  Earth, as we saw with Skylab In Australia in
• 31:27
  1973, for example, um, and more
• 31:30
  recently with fragments of SpaceX debris
• 31:33
  littering the planet, you might think that if
• 31:36
  it falls in your backyard, it's yours, but it
• 31:38
  isn't. The ownership remains with the people
• 31:41
  or the country that launched it. And so
• 31:44
  back when Skylab, um, landed in Western
• 31:47
  Australia, the area in Western Australia
• 31:49
  where it landed cheekily sent NASA a
• 31:52
  littering notice for a fine, which got paid,
• 31:55
  um, which was quite good fun a few years ago
• 31:57
  when large pieces of SpaceX rocket landed in
• 32:00
  the Snowy Mountains in Australia.
• 32:02
  Andrew Dunkley: Yes.
• 32:02
  Jonti Horner: People were advised not to pick the bits up
• 32:04
  and collect them to let the Australian Space
• 32:06
  Agency know, because technically,
• 32:09
  the space agency has a whole plan. And this
• 32:11
  is laid out on the space agency website under
• 32:13
  space.govau
• 32:16
  discovery of space
• 32:18
  debris in Australia. So
• 32:21
  space.govau discovery of space
• 32:24
  debris in Australia details
• 32:26
  the regulatory side of things and what the
• 32:29
  space agency does, and says the Australian
• 32:32
  government has plans in place for events
• 32:33
  where space debris impacts Australia.
• 32:36
  Description of what it is and what the role
• 32:37
  is, and it lays out the steps that if you
• 32:39
  find space debris in your backyard, you
• 32:41
  should follow. Step one is do not touch it.
• 32:44
  And I cannot stress this enough, do not touch
• 32:46
  it. Space objects are built from materials
• 32:48
  that can be hazardous. This is exacerbated by
• 32:51
  coming back through the atmosphere and
• 32:52
  getting damaged. So it says space debris
• 32:55
  should only be handled by appropriately
• 32:56
  trained and equipped professionals. That was
• 32:59
  particularly relevant with the fragments of
• 33:01
  the SpaceX rocket that fell near the Turks
• 33:03
  and Caicos Islands earlier this year, because
• 33:05
  there was a whole brouhaha about the cleanup
• 33:07
  and SpaceX was not following its requirements
• 33:10
  and not doing much, and people were upset and
• 33:12
  some people had been going and collecting
• 33:14
  bits of debris and there was a risk they'd
• 33:15
  fall ill and stuff like this. So, step one,
• 33:18
  don't touch it. Step two, contact your local
• 33:20
  authorities. So, um, if the situation is
• 33:23
  urgent, contact triple zero. So I guess
• 33:25
  that's if a piece of a SpaceX satellite hits
• 33:27
  your Tesla, don't contact the museum, call
• 33:30
  the police. Fair enough. Otherwise, call the
• 33:32
  police assistant line. So you get some advice
• 33:35
  and Then you notify the space agency. And
• 33:37
  what the space agency then has to do is
• 33:40
  figure out whose bit of debris it is, get in
• 33:43
  touch with them, um, and liaise with them
• 33:45
  because there is a requirement for us to
• 33:47
  return the material to them. It is their
• 33:50
  property. And um, so from
• 33:52
  salvaging here on Earth you don't have those
• 33:55
  salvage laws because even if it's a burnt up
• 33:57
  fragment of rocket, it's still property of
• 33:59
  SpaceX or it's still property of the Chinese
• 34:01
  government. And so we don't have that kind of
• 34:04
  salvage set up at the minute. There's a
• 34:06
  description of what happens once debris is
• 34:08
  identified as space debris. And it says if an
• 34:10
  item is confirmed as space debris, the
• 34:12
  Australian government has international
• 34:14
  obligations to notify the launching authority
• 34:16
  of the discovery and upon request may be
• 34:19
  required to return the debris. So you
• 34:22
  can't salvage it. Now this
• 34:25
  may become something where the laws evolve in
• 34:28
  the years to come. As I say all the time our
• 34:30
  uh, user space is still in this Wild west
• 34:32
  phase where our ability to do stuff is
• 34:35
  growing much more rapidly than our ability to
• 34:37
  legislate for it. Um, and there's a lot of
• 34:39
  commercial interest in not advancing the
• 34:41
  legislation because if you advance the
• 34:44
  legislation you put more costs on the
• 34:46
  commercial entities. So they have a vested
• 34:47
  interest in not having legislation about
• 34:50
  launches, not legislating for the number you
• 34:52
  can make or the environmental requirements.
• 34:55
  And countries are leery of doing it because
• 34:57
  you can launch the space from all over the
• 34:59
  globe. So if you say to uh, SpaceX,
• 35:02
  you need to meet all these punishing
• 35:04
  environmental conditions before you launch
• 35:06
  and you've got to do all this with your
• 35:07
  satellites, SpaceX can easily say, well
• 35:10
  that's fine, we'll take our investment and
• 35:11
  move it to another country. So there's a lot
• 35:14
  of challenges there. But I could imagine in
• 35:16
  decades to come, as commercial space becomes
• 35:18
  more established and our use of space becomes
• 35:20
  much more varied and much more numerous,
• 35:23
  a astronomers will complain because you get
• 35:25
  more and more spoiling of the night sky, but
• 35:27
  you'll also get the opportunity for
• 35:29
  businesses, just like this question
• 35:30
  describes, to develop why there may be the
• 35:33
  commercial value for people to recover
• 35:35
  defunct satellites in orbit, capture them,
• 35:38
  maybe even lift them up to a higher orbit to
• 35:40
  a factory that can process the materials and
• 35:43
  let people then build new satellites in
• 35:44
  orbit. That way you lower the risk of them
• 35:47
  burning up in Earth's atmosphere, you get rid
• 35:49
  of the possibility of them altering the
• 35:51
  atmosphere to make climate change worse or
• 35:53
  better, as we discussed before. And um,
• 35:55
  you'll lower the cost of launching new ones
• 35:57
  if you could reprocess and salvage and
• 35:59
  rebuild. Yeah, it's probably not commercially
• 36:01
  feasible yet, which is why nobody's doing it
• 36:03
  yet. But it may well become so and so. This
• 36:06
  is something that I'd expect to evolve in the
• 36:08
  next say 50 years as all this stuff becomes
• 36:11
  more entrenched.
• 36:13
  Andrew Dunkley: It's interesting uh, in regard to the
• 36:15
  ownership side of things. Uh, it's like when
• 36:17
  you put your garbage bin out with all your
• 36:19
  stuff in it, it's still your stuff. And even
• 36:22
  as far as it being dumped in
• 36:25
  landfill, if you've thrown out your son's
• 36:27
  favorite toy and he wants it back, it's still
• 36:30
  his toy. So it's
• 36:33
  the same kind of thing, um, in a down to
• 36:36
  earth kind of way. And to our YouTube Music
• 36:38
  listener, um, just one final
• 36:41
  point.
• 36:41
  Jonti Horner: Yes.
• 36:42
  Andrew Dunkley: There are companies researching salvage in
• 36:45
  space.
• 36:46
  Jonti Horner: Newman.
• 36:46
  Andrew Dunkley: Ah space. Another one called AstroDailyPod
• 36:48
  Scale and of course the major parties, NASA
• 36:51
  and ESA and several others are
• 36:54
  looking into this. Uh but right now it's,
• 36:56
  it's not a very easy thing to do. But thanks
• 36:59
  for the question. Thanks for the question.
• 37:01
  Really good.
• 37:04
  Okay, we checked all four systems and being
• 37:06
  with a go space nats, uh, we have one
• 37:09
  final question. This one comes from Robert
• 37:12
  and Robert uh, is from the Netherlands
• 37:15
  uh, and he's got backing music on his
• 37:17
  question.
• 37:18
  Robert: Hello, this is Robert from Netherlands. I
• 37:21
  have a question for you today about radio
• 37:24
  waves because as we all know it's a very
• 37:27
  efficient low energy way of communicating
• 37:31
  data over vast distances. And
• 37:34
  I would think that if we are looking for
• 37:36
  aliens which I find very tantalizing at
• 37:38
  the subject, we should be looking for radio
• 37:41
  waves probably like 500
• 37:44
  light years of a radius of the earth which
• 37:48
  seems to be kind of a low priority. Never
• 37:50
  understood why, why there's there's a
• 37:53
  beanbags uh, observatory that can
• 37:56
  know really pinpoint these but you can't
• 37:58
  really cast a white net so to speak. Another
• 38:01
  square kilometer ray might be capable of
• 38:04
  this being built. Australia of course. I
• 38:07
  was hoping you guys would have some insights.
• 38:09
  They're going to be interact radio waves.
• 38:12
  Thank you so much time.
• 38:14
  Andrew Dunkley: Um, thank you Robert. Lovely
• 38:17
  music. Yeah, very, very spacey
• 38:20
  indeed. Um, I would have thought that
• 38:23
  that's prime target number one when
• 38:26
  searching for life beyond Earth. Um,
• 38:29
  would be to be listening for radio waves
• 38:32
  and, and Robert's right, the Square Kilometer
• 38:34
  Array will be capable for that. I think it be
• 38:37
  able to pick up airport radar uh
• 38:39
  as far away as 50 light years.
• 38:42
  Jonti Horner: Yes, it's an incredible, incredible tool and
• 38:45
  in fact this is what people have been doing.
• 38:47
  So this is the whole foundation of a subset
• 38:50
  of our science called seti, the Search for
• 38:52
  Extraterrestrial Intelligence. Often you
• 38:54
  describe this as a search for a needle in a
• 38:56
  hair stack, where you don't know what a
• 38:57
  needle looks like and you've never seen a
• 38:59
  hair stack before. So if you're trying to
• 39:02
  find life that is as technologically
• 39:05
  advanced as us, or more. So then there
• 39:08
  is an argument that listening for signals
• 39:10
  would be a good way to do it. And kind of
• 39:12
  corroborating that is the idea that we are
• 39:14
  broadcasting into the voyage, screaming like
• 39:17
  a toddler in a dark cave with our
• 39:20
  radio broadcasts and, um, our TV broadcasts
• 39:22
  and all this stuff with radio waves. And it's
• 39:25
  often argued that either the Berlin Olympics,
• 39:27
  which I think were 1936, or the coronation of
• 39:30
  Queen Elizabeth the Second in possibly 1952.
• 39:33
  1953, yeah, were the first broadcasts that
• 39:35
  were powerful enough that would be easily
• 39:37
  detected from elsewhere. So if you were
• 39:40
  magically able to take the Square Kilometer
• 39:42
  Array and place it as a star, ah, within
• 39:45
  about 80 light years of the Earth, you'd be
• 39:48
  able to listen in and watch the development
• 39:49
  of our technological society as our
• 39:52
  broadcasts get more numerous and more varied.
• 39:54
  You'd probably be able to broadcast back and
• 39:57
  say, please stop broadcasting, neighbours,
• 39:58
  we're sick of it. We want to know more about
• 40:01
  Scott and Charlene or whatever, um, people
• 40:04
  will be able to listen in. And so this gives
• 40:05
  everybody the idea that just like this
• 40:07
  question, we could do the same thing and we
• 40:09
  could try and tune in onto the broadcasts of
• 40:12
  other societies. And that's
• 40:15
  fundamentally the foundation of seti. Back
• 40:18
  when I was an undergraduate, back when I was
• 40:20
  at high school, in the early days of personal
• 40:22
  computing, there was a program called SETI at
• 40:24
  home, which was a way of distributing through
• 40:27
  cloud computing, packets of data obtained by
• 40:30
  radio telescopes to search for signals of
• 40:32
  radio broadcasts. And nothing was found.
• 40:35
  There are global usage of radio telescopes
• 40:38
  around the world to try and do this still.
• 40:39
  The most famous of them these days is the
• 40:41
  Breakthrough Listen Initiative, which was
• 40:44
  funded to the tune of $100 million starting
• 40:46
  back in 2015. So it's 10 years old now.
• 40:49
  That did a wonderful thing for Australia
• 40:52
  because the government at the time in
• 40:53
  Australia was our, um, less
• 40:56
  science friendly party, let's put it that
• 40:58
  way. And, uh, they were looking to save money
• 41:00
  by killing science, as often happens, and
• 41:03
  that's having knock on effects nowadays. But
• 41:05
  one of the things they wanted to do was close
• 41:07
  the dish, the Parks Radio Observatory,
• 41:11
  which is the Biggest, most iconic observatory
• 41:14
  building I think in Australia, famous for
• 41:16
  awesome movie the Dish with Sam Neill many
• 41:18
  years ago.
• 41:18
  Andrew Dunkley: And it's just down the road from.
• 41:20
  Jonti Horner: Where I live, just down the road. And there
• 41:22
  was a lot of upset that this wonderful
• 41:23
  facility was going to be mothballed and
• 41:25
  closed down to cut budgets,
• 41:28
  um, because, you know, they wanted to put
• 41:30
  more money into fossil fuel extraction to
• 41:32
  satisfy their donors or whatever. I, um, have
• 41:35
  views anyway, many do.
• 41:38
  Parks was saved by an injection of a very
• 41:41
  large sum of money from the Breakthrough
• 41:43
  Listen initiative, which has kept the
• 41:45
  telescope operating for another decade.
• 41:47
  There's a lot of awesome new science has come
• 41:49
  out of it as a result, but it is bought a
• 41:51
  certain fraction of the time of that
• 41:53
  telescope, which I think is about 40% to
• 41:55
  specifically point that telescope around the
• 41:57
  star to listen to radio broadcasts, to
• 42:00
  look for radio broadcasts from nearby stars.
• 42:04
  And there's been a number of papers come out
• 42:06
  on this over the years that detail
• 42:09
  the incredible work people have done. And to
• 42:11
  illustrate the challenge of these things,
• 42:12
  there's been a few occasions where people
• 42:14
  think there's been a potential signal only
• 42:16
  for it to be turned out to be something else.
• 42:19
  One example was that they thought they'd
• 42:21
  found a potential signal. And when they
• 42:22
  investigated more, it happened at the same
• 42:24
  time every evening and investigated more. And
• 42:26
  it was that the astronomers were walking
• 42:28
  across one of the building and putting their
• 42:29
  food in the microwave. Yes, the building was
• 42:32
  shielded. They were picking up the radiation
• 42:34
  from the microwaves, you know, so it's really
• 42:36
  hard to do today. We have found
• 42:39
  nothing. No. And ah, there are some arguments
• 42:41
  that, uh, it's very unlikely we will do.
• 42:43
  That's a needle in a hair sack thing.
• 42:46
  Firstly, we need to figure out where
• 42:49
  in the radio spectrum to look. And um, the
• 42:51
  radio wave frequency spectrum spans an
• 42:54
  enormous range. A lot of efforts have been
• 42:56
  focused around the hydrogen 21 centimeter
• 42:59
  line viewing. That has been an obvious place
• 43:01
  for people who are deliberately broadcasting
• 43:03
  to broadcast, because everyone will know
• 43:05
  about that. But in terms of accidental
• 43:07
  broadcasts like what we're doing on the
• 43:09
  Earth, there's no guarantee that another
• 43:11
  species would pick the same frequencies that
• 43:13
  we've chosen for the broadcast. So we might
• 43:16
  be listening to the wrong tune, we might just
• 43:18
  be listening at the wrong frequency. The
• 43:21
  other thing though is that, uh, the kind of
• 43:22
  broadcasting we've been doing for the last
• 43:24
  hundred years is incredibly energy
• 43:25
  inefficient because we broadcast in
• 43:28
  all directions at ah, once.
• 43:31
  To have a very small number of directions
• 43:34
  pick up that signal, you know, all your TV
• 43:35
  aerials Or whatever. It is much more
• 43:38
  efficient to do point to point communications
• 43:40
  or to send things through optical cables.
• 43:43
  So there is some argument that as your
• 43:45
  technology gets better, the amount of waste
• 43:47
  noise you broadcast to space will fall off.
• 43:49
  Yes. And so there's an argument that in the
• 43:51
  next 30 or 40 years the Earth will become
• 43:53
  radio silent again. So then there'll be this
• 43:56
  little bubble around the earth getting bigger
• 43:57
  and bigger where if you're in that bubble,
• 43:59
  you hear our radio broadcast, but then
• 44:01
  there's a smaller bubble in the middle where
• 44:03
  we go silent again.
• 44:04
  Andrew Dunkley: Yeah.
• 44:05
  Jonti Horner: And it may be that every technological
• 44:06
  species is only loud when it's in its
• 44:08
  infancy, when it is that toddler screaming
• 44:11
  that they don't want to leave the beach like
• 44:12
  the kid I saw yesterday. And eventually
• 44:15
  a uh, society learns to self regulate and
• 44:18
  has more efficient ways of broadcasting. So
• 44:21
  it is a fabulous question. If you want to
• 44:24
  learn more about it. I do recommend looking
• 44:26
  up and googling and reading around SETI as a
• 44:28
  project SETI at home and the Breakthrough
• 44:30
  Listen initiative. You can also look up
• 44:33
  an associated thing which is mete. Mete,
• 44:36
  which is, I think METE is the acronym which
• 44:39
  is a search for the artifacts of advanced
• 44:42
  civilizations. Oh, and I know colleague
• 44:45
  of mine in the US who's part of our planet
• 44:47
  search team has put out a few papers looking
• 44:50
  at things that appear in science fiction like
• 44:53
  Dyson spheres and ringworlds and
• 44:56
  what effect they would have on the light from
• 44:58
  their stars. So what the observational
• 45:00
  signatures would be not with any
• 45:03
  expectation that we'll ever find them, but
• 45:05
  because if we don't model what they would be
• 45:06
  like, if we ever see something that displays
• 45:09
  that odd behavior, we wouldn't know what it
• 45:10
  was. So it's again this very low
• 45:13
  likelihood of finding something, but very
• 45:15
  high reward if you ever do. I
• 45:18
  guess that people are actually actively
• 45:20
  thinking about what could we feasibly do
• 45:23
  as a technological civilization in the future
• 45:25
  with improving technology. How would that
• 45:27
  affect our environment around the sun? How
• 45:30
  would that affect the way that our planetary
• 45:32
  system pairs from around other stars? And uh,
• 45:35
  what would that look like if we saw a
• 45:36
  different civilization doing it? So that we
• 45:39
  have the predictions there so that when we
• 45:41
  get vast amounts of data from these all sky
• 45:43
  surveys, whether they be in the radio or
• 45:46
  whether they be in the optical, we can
• 45:48
  identify the oddities and figure out what
• 45:50
  they are. And similarly with a square
• 45:52
  kilometer array that will be pointing all
• 45:54
  over the sky, doing lots of astronomy, but
• 45:57
  the data from that will be analyzed by teams
• 45:59
  who are interested in could there be an alien
• 46:01
  signal buried in this. So you will get
• 46:04
  serendipitous imaging there because wherever
• 46:06
  it's looking, you get the data and you can
• 46:08
  survey that to see what there is. So it is
• 46:10
  something people are actively doing. You're
• 46:13
  onto something good there. And I can
• 46:14
  recommend, like I said, reading about
• 46:15
  breakthrough lists and reading about SETI to
• 46:18
  learn more about it, if that is what you're
• 46:20
  interested in it.
• 46:20
  Andrew Dunkley: Yeah, uh, it'd be uh, interesting to
• 46:23
  discover another race somewhere
• 46:26
  out there that's uh, built a megastructure,
• 46:28
  um, like, oh, I don't know, a space parasol
• 46:32
  array of some kind. Imagine that same
• 46:35
  problem. Someone else has solved it. Yeah,
• 46:37
  uh, we are going to be.
• 46:38
  Jonti Horner: Doing a little, little baby test of that
• 46:40
  potentially in the next 10 or 20 years if
• 46:42
  NASA ever gets its funding back. There is the
• 46:45
  Habitable Worlds Observatory that is
• 46:48
  looking at planets around other stars. And
• 46:51
  um, what they're proposing to do to allow
• 46:53
  them to gather light from planets the size of
• 46:55
  the Earth, uh, around stars like the sun, is
• 46:57
  reflectively fly a very giant,
• 46:59
  beautifully designed, very intricate,
• 47:01
  fractally edged, um, space
• 47:04
  parasol that would go out about 100,000
• 47:06
  km from the telescope and fly in formation,
• 47:09
  line up to block the light from stars so that
• 47:11
  we can see the planets going around them.
• 47:13
  Now that size of parasol would be way too
• 47:16
  small to impact climate change, but it's a
• 47:18
  really good tech demonstrator. It shows that
• 47:20
  we can do that and we can get the station
• 47:22
  keeping just much too small. And again, if
• 47:24
  people are interested in that looking up, the
• 47:26
  Habitable Worlds Observatory would be a
• 47:29
  good place to look. And there's some lovely
• 47:30
  videos of the animation of this thing being
• 47:32
  launched and unfolding and moving out in
• 47:34
  space. And they've even done tests in labs
• 47:37
  for mini versions of it on long corridors to
• 47:40
  prove the concept works.
• 47:42
  Andrew Dunkley: All very cool, very cool indeed. And uh, a
• 47:45
  cool question too, Robert. Thanks for sending
• 47:46
  it in. And if you would like to send us
• 47:48
  questions, don't Forget our website
• 47:50
  spacenutspodcast.com
• 47:52
  spacenuts IO and
• 47:55
  uh, click on the AMA link and you can send us
• 47:58
  text, uh, and audio questions, uh, through
• 48:00
  that system. And uh, we'd be happy to get
• 48:03
  them and we'll do our very best to answer
• 48:04
  them. Sometimes we get the same questions,
• 48:07
  um, which is not unusual if people sort of
• 48:10
  hone in on a topic. Uh, so we will,
• 48:12
  um, if we don't answer your question, it's
• 48:14
  possibly because we've already done it, uh,
• 48:17
  but we do redo questions from time to time
• 48:19
  because they keep coming up, um, particularly
• 48:21
  black hole questions. We quite often get a
• 48:24
  repeat. Might be a couple of years later, but
• 48:26
  we get a repeat of a question we've already
• 48:28
  covered. So we'll, we'll sometimes redo them.
• 48:31
  But, uh, good to hear from you, Robert.
• 48:32
  Thanks to everyone who contributed and thanks
• 48:34
  to you, Jonti, for having a crack at the
• 48:37
  answers.
• 48:38
  Jonti Horner: That's all good. It's what I'm here for. And
• 48:39
  it's fun to face new and interesting
• 48:42
  questions.
• 48:42
  Andrew Dunkley: It is indeed. Uh, we'll see you on the next
• 48:45
  episode. Jonti, uh, Horner, professor of
• 48:47
  Astrophysics at the University of Southern
• 48:49
  Queensland. And thanks to Huw in the studio.
• 48:52
  Not, um, sure you're aware that Huw used to
• 48:55
  work in radio. That's how we actually met. In
• 48:57
  fact, he was working at a radio station, uh,
• 49:00
  in Newcastle in New South Wales when I was a
• 49:03
  kid and I did job experience there. And
• 49:04
  that's how I met Huw originally, when I was
• 49:06
  about 13 years old or something.
• 49:09
  Anyway, he's an old radio man these days
• 49:12
  and, uh, when it comes to radio waves,
• 49:15
  he feels that that means he should stand out
• 49:17
  the front waving at traffic. That's why he's
• 49:20
  not with us today. And he may never come
• 49:22
  back. And from me, Andrew Dunkley, thanks for
• 49:24
  your company. I'll see you on the next
• 49:27
  episode of Space Nuts. Bye. Bye.
• 49:30
  Jonti Horner: You'll be listening to the Space Nuts.
• 49:32
  Robert: Podcast.
• 49:34
  Jonti Horner: Available at Apple Podcasts, Spotify,
• 49:37
  iHeartRadio or your favorite podcast
• 49:40
  player. You can also stream on demand at
• 49:42
  bytes. Com.
• 49:44
  Andrew Dunkley: This has been another quality podcast
• 49:46
  production from Bytes.
• 49:47
  Jonti Horner: Com.
• 49:48
  Speaker C: Um.