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Cosmic Life Hunt: Delving into Astrobiology Part 2 & the Quest for Extraterrestrial Existence · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Andrew Dunkley: Hi there. Thanks for joining us again. This
• 0:01
  is Space Nuts where we talk astronomy and
• 0:04
  space science and all sorts of other things.
• 0:07
  And over the last, uh, few
• 0:10
  episodes we've been doing some specials
• 0:13
  because Fred Watson's away gallivanting
• 0:15
  around Scotland playing a lot of golf. Not.
• 0:18
  Uh, so we're doing some specials with Jonty
• 0:21
  Horner. Uh, and we're doing part
• 0:24
  two today of
• 0:25
  Astrobiology, a fascinating
• 0:28
  part of astronomy and space science. Uh,
• 0:31
  one area we get so many questions about. So
• 0:34
  stand by as we get into that on this
• 0:37
  episode of space nuts. 15
• 0:40
  seconds.
• 0:40
  Jonti Horner: Guidance is internal. 10,
• 0:43
  9, ignition sequence start.
• 0:46
  Space nuts. 5, 4, 3, 2. 1. 2,
• 0:49
  3, 4, 5, 5, 4, 3, 2, 1.
• 0:51
  Space nuts.
• 0:53
  Andrew Dunkley: Astronauts report it feels good.
• 0:56
  And back with us again is Johnty Horner,
• 0:58
  professor of astrophysics at the University
• 1:00
  of Southern Queensland. Jonty, hello.
• 1:02
  Jonti Horner: Noon. How are you?
• 1:03
  Andrew Dunkley: I'm m all right. Can you imagine Fred Watson
• 1:05
  playing golf?
• 1:06
  Jonti Horner: No, uh, not sure. I mean, growing up in
• 1:08
  Yorkshire, the weather wasn't always suited
• 1:10
  to it and we were too busy in gravel anyway,
• 1:13
  so.
• 1:14
  Andrew Dunkley: Yeah, took
• 1:17
  a moment. I got that. Yes, yes.
• 1:20
  Uh, used to look clean with the tongues.
• 1:22
  Jonti Horner: Used to have to get up in the morning at 10
• 1:24
  o' clock at night, half an hour before I went
• 1:25
  to bed.
• 1:27
  Andrew Dunkley: It's just one of the best pieces of comedy
• 1:30
  ever.
• 1:30
  Jonti Horner: And it's funny because it's true.
• 1:33
  Yes.
• 1:34
  Andrew Dunkley: Tell the young people that.
• 1:36
  Jonti Horner: They won't believe you.
• 1:39
  Andrew Dunkley: Oh gosh, it's all flooding back. Uh, we've
• 1:42
  got a lot to talk about so we better get
• 1:44
  started.
• 1:44
  Astrobiology Part two. Um,
• 1:47
  a couple of episodes ago we talked
• 1:49
  Astrobiology Part one, surprisingly. Um,
• 1:52
  let's just do a quick review.
• 1:54
  Jonti Horner: Yeah, this is a bit like the bit that really
• 1:56
  annoys you at the start of those multi
• 1:59
  episode shows where they're previously on
• 2:01
  Astrobiology. Um, but
• 2:05
  this is basically a case of Jonty talks too
• 2:07
  much and so therefore we run out of time. I
• 2:09
  mean, we don't need to sugarcoat that. And
• 2:11
  it's always a problem when you're talking
• 2:13
  about something you love and you're
• 2:14
  passionate about that. The time just flies by
• 2:16
  and hopefully it's flying by for the
• 2:18
  listeners as well, rather than boring them to
• 2:20
  tears. But you know, I can't really control
• 2:22
  that. In the first episode
• 2:25
  we talked a fair bit about the fact that
• 2:27
  we've always wondered whether there's life
• 2:29
  elsewhere. We talked a bit about the history
• 2:31
  in particular things like the ideas of
• 2:33
  potentially there being life on Mars that led
• 2:35
  to the panic over the War of the Worlds
• 2:37
  broadcast and the Fact that In the late
• 2:39
  1800s, people were that convinced there
• 2:41
  already was known to be life on Mars, that
• 2:43
  when a major prize was offered for the
• 2:45
  detection of life elsewhere, Mars was
• 2:47
  explicitly excluded because that's too easy,
• 2:49
  you know. So we've had these ideas for a very
• 2:51
  long time, but finding evidence of life
• 2:54
  out there is really, really difficult.
• 2:57
  We've talked a fair bit about the search for
• 2:59
  life within the solar system. You know,
• 3:02
  places like looking at Mars, looking at
• 3:04
  Europa, all the icy moons. And we talk about
• 3:06
  that a lot in the questions that we week by
• 3:08
  week as well on the show.
• 3:09
  And one thing I've always been really
• 3:12
  interested in and passionate about is the
• 3:13
  search for life outside the solar system.
• 3:16
  Given that we've moved into the exoplanet
• 3:18
  era, and we talked a lot about this in the
• 3:20
  previous episode as well, we're now in a
• 3:22
  position where 30 years ago would have seemed
• 3:24
  impossible. Thirty years ago, we'd only just
• 3:26
  found the first planet for under the Stars,
• 3:28
  and only just answered that question of
• 3:30
  whether there are planets at all beyond the
• 3:32
  solar system. Now we're at a position where
• 3:35
  we are finding places that theoretically, in
• 3:37
  the future, we could search to see whether
• 3:40
  there's any evidence of life in those
• 3:42
  planetary systems. And in all honesty,
• 3:44
  despite some of the hyperbolic media
• 3:47
  articles that you sometimes see, we haven't
• 3:49
  yet found a planet that would really look
• 3:52
  like another Earth. But we're getting there,
• 3:53
  we're getting closer, we're getting to
• 3:55
  planets that are more similar to ours in
• 3:57
  size, at more similar distance from their
• 3:59
  stars, and we're learning more about them.
• 4:01
  And it's very feasible then in the next
• 4:03
  decade or so, that we can actually start
• 4:05
  looking to see whether there's any evidence
• 4:07
  of life on those planets. Now, that's a
• 4:09
  little bit separate to looking for signs of
• 4:12
  communicative alien technological
• 4:15
  life, which is a search for extraterrestrial
• 4:17
  intelligence or the search for
• 4:19
  extraterrestrial artefacts. There two areas
• 4:20
  of science that are fascinating, but they're
• 4:23
  more like a search for a needle in a hair
• 4:25
  sack, where we don't even know if there is
• 4:28
  life elsewhere, never mind intelligent life.
• 4:30
  I mean, some people argue whether there's
• 4:32
  intelligent life on Earth looking at the news
• 4:34
  at the minute, but looking for intelligent
• 4:36
  life that has reached certain technological
• 4:38
  level to communicate with us is challenging.
• 4:41
  It's one of those things if we don't know
• 4:42
  what we're looking for, but if we don't look,
• 4:44
  we'll never find it. But it still led to some
• 4:47
  really fascinating research, and there's a
• 4:49
  guy who works with us as part of our Planet
• 4:51
  Search Consortium, a guy called Jason Reutt
• 4:53
  in the US who spent some of his time actually
• 4:56
  thinking about alien megastructures, the
• 4:59
  kind of things that feature so heavily in
• 5:01
  some advanced science fiction, like Larry
• 5:03
  Niven's Ringworld or Dyson Spheres, these
• 5:06
  enormous structures that you can imagine a
• 5:09
  civilization building. If their technologies
• 5:11
  are far above ours, as ours is from the Stone
• 5:14
  Age, the idea that you could build something
• 5:16
  to harness all the material in your planetary
• 5:18
  system m harness all the energy from your
• 5:20
  star. Now, many people argue that while
• 5:22
  that's theoretically possible, it just
• 5:23
  wouldn't be worth the effort. But what
• 5:26
  Jason's been looking into is
• 5:29
  effectively not could people do
• 5:31
  this? But rather if they did, what would it
• 5:34
  look like? So it's not really putting any
• 5:36
  weight on the probability of
• 5:39
  these things existing, but rather saying,
• 5:41
  here are things we could imagine that are
• 5:44
  within the bounds of physical possibility to
• 5:46
  build. Even if they'd be on this
• 5:47
  technologically, what would they look like to
• 5:50
  our different kinds of telescopes? What would
• 5:52
  the signatures be? And, um, that work's
• 5:54
  really important because if you don't have an
• 5:57
  idea what these peculiar objects would look
• 5:59
  like, when you find something unusual, you
• 6:02
  won't have that thing to reference again to
• 6:04
  cheque it out. So both the search for
• 6:06
  extraterrestrial intelligence and the search
• 6:08
  for alien artefacts, a kind of
• 6:11
  a separate splinter of astrobiology that are
• 6:14
  ongoing, that are very precious to us here in
• 6:16
  Australia. Of course, we would have lost the
• 6:17
  Parks Radio telescope under the Liberal
• 6:20
  government in the 2010s in the previous
• 6:22
  decade because they wanted to shut it down
• 6:25
  and demolish it to save money. And it only
• 6:27
  kept going by a large investment
• 6:30
  as part of a project to listen
• 6:33
  for aliens. So, like 40. I remember
• 6:36
  that telescope has been used to search for
• 6:38
  extraterrestrial intelligence in the form of
• 6:40
  radio signals. And that has kept one of our,
• 6:43
  uh, incredible pieces of astronomical
• 6:44
  heritage in Australia. And something
• 6:46
  incredibly precious and beloved has kept it
• 6:48
  going and kept it standing despite the worst
• 6:50
  vagaries of politicians and
• 6:53
  all those challenges.
• 6:55
  Andrew Dunkley: Could you argue that we, uh, have
• 6:58
  already created a
• 7:00
  megastructure around Earth with the number of
• 7:03
  satellites that are currently in orbit and
• 7:05
  the so many thousands more that are going to
• 7:08
  be put up there in the near future?
• 7:09
  Jonti Horner: Certainly feels like that from the inside.
• 7:11
  Looking out. I mean, I'm enjoying all the
• 7:13
  photos. People are, uh, of Comet 2025
• 7:16
  R3 Pan stars at the minute, which behind
• 7:19
  both of us are our attempts. We're showing
• 7:20
  them off. Andrew's ever so proud from his
• 7:22
  attempt last night.
• 7:24
  Andrew Dunkley: My first ever comet.
• 7:25
  Jonti Horner: Fabulous photos that people are getting, but
• 7:27
  I've seen a lot of them getting photobombed
• 7:29
  by Starlink satellites. And I've got. I'm
• 7:32
  currently, thanks to learning something new
• 7:34
  about astrophotography over the last two
• 7:35
  days. I'm going back to images I took of
• 7:37
  Comet Atlas and Comet um, Church in Chan
• 7:39
  Atlas, which were the great comets of 2024
• 7:41
  and 2025 to reprocess those
• 7:44
  images. But one of my abiding Comet Atlas
• 7:47
  was I had this incredible view of it on the
• 7:49
  horizon. Took this long series of photos and
• 7:51
  every single blooming photo was ruined by a
• 7:54
  Starlink satellite because I got a Starlink
• 7:55
  train passing overhead that had recently been
• 7:57
  launched. All of which went straight through
• 7:59
  the middle of the comet and rendered all the
• 8:01
  photos unusable on my only really good clear
• 8:03
  night. Now, I may be able to solve it, but
• 8:06
  that isn't quite at the megastructure stage
• 8:08
  yet for me in that I suspect with the
• 8:11
  level of technology we've got now or in the
• 8:13
  near future, that network of
• 8:16
  satellites around the Earth, uh, wouldn't be
• 8:17
  something we could detect orbiting a planet
• 8:20
  around another star. Right. They're not there
• 8:22
  yet, but they're the forebears of something
• 8:24
  that could be. Now, being that
• 8:27
  they're around a planet rather than a star,
• 8:29
  their signature will be different. And given
• 8:31
  that we are very skilled now at
• 8:34
  broadcasting in one direction rather than
• 8:36
  many, and that broadcasting directionally
• 8:38
  rather than broadcasting the boy band one
• 8:40
  direction should be said, um, broadcasting
• 8:44
  in a directional sense. We are moving towards
• 8:46
  the point where we're going to stop shrieking
• 8:48
  like a screaming infant into the cosmos
• 8:50
  anyway. So it may be that we're going to go
• 8:52
  radio silent fairly soon, and satellites like
• 8:54
  that are going to be part of that journey.
• 8:57
  But I think they are an indication of how
• 8:59
  quickly these things can happen. You know, if
• 9:01
  we were talking a decade ago, we'd have been
• 9:03
  talking about a couple of thousand satellites
• 9:05
  orbiting Earth. We're now talking about
• 9:07
  roughly 50,000. With plants have more than a
• 9:09
  million within the next decade, it's getting
• 9:13
  quite terrifying, actually. As much from the
• 9:16
  atmosphere and climate side of things as
• 9:18
  anything else. You know, if we have a million
• 9:20
  Starlink satellites in orbit in five years or
• 9:23
  10 years time, they have an average lifetime
• 9:26
  of five years, which means we'd have more
• 9:27
  than 500 per day burning up in the
• 9:29
  atmosphere. And that's
• 9:32
  a factor of 100, if not more times
• 9:35
  material entering the atmosphere on a daily
• 9:37
  basis than we get from the background of
• 9:39
  space stuff falling in. We'll be running an
• 9:42
  experiment in atmospheric science that we've
• 9:44
  never run, dumping hundreds of
• 9:47
  tonnes of aluminium into the upper atmosphere
• 9:49
  every day.
• 9:50
  Andrew Dunkley: Yeah, what's the effect going to be? And
• 9:52
  that's the $64,000 question, I suppose.
• 9:55
  Jonti Horner: But now the interesting thing there, coming
• 9:57
  back to the astrobiology, is that might
• 10:00
  well create a signature in the Earth's
• 10:02
  atmosphere that would be detectable
• 10:05
  from observers from around another star.
• 10:08
  Because one of the ways that we would look
• 10:10
  for biosignatures, at least early
• 10:13
  on, will be to look at the light
• 10:16
  from a star reaching us whilst a given
• 10:19
  planet is transiting between us and the star,
• 10:21
  so blocking a bit of that star's light. We
• 10:24
  can currently do this with giant planets,
• 10:25
  Jupiter sized, and a fraction of the light
• 10:28
  from the star passes through the planet's
• 10:30
  atmosphere. And you get imprinted on the
• 10:33
  stars like the chemical fingerprint of the
• 10:35
  constituents of the outer layers of the
• 10:37
  atmosphere where the lights pass through in
• 10:39
  the form of absorption lines. And um, by
• 10:41
  studying them, we can work out some of the
• 10:43
  chemical species that are prevalent there and
• 10:45
  even learn a bit about the structure of the
• 10:46
  atmosphere, the presence of clouds, things
• 10:48
  like that. Now when we get to the point where
• 10:51
  we've got all those satellites burning up in
• 10:53
  our atmosphere, imagining with the kind of
• 10:56
  technology that we're looking at developing
• 10:57
  within the next decade or so, or maybe a
• 11:00
  little bit longer, imagining being on a
• 11:02
  nearby star looking at the sun while the
• 11:04
  Earth is transiting, you're suddenly
• 11:06
  introducing a huge spike of aluminium and
• 11:09
  into the absorption in an Earth like planet's
• 11:11
  atmosphere. And there is no natural way that
• 11:14
  I'm aware of that you could get that.
• 11:17
  So that would not only be a sign of something
• 11:19
  way going on, it would be a bio signature of
• 11:21
  technologically developed life that is not
• 11:24
  quite so developed as to have learned that
• 11:26
  pollution is bad.
• 11:28
  Andrew Dunkley: Maybe that's how we find an
• 11:30
  intelligent species, uh, beyond Earth.
• 11:33
  They find us first and send us a, you
• 11:36
  know, welcome pack.
• 11:37
  Jonti Horner: Yes. 10 helpful things you can do to fix your
• 11:40
  problems. Stop burning things up in the
• 11:42
  atmosphere.
• 11:44
  Andrew Dunkley: Um, yes, yeah, they may have already
• 11:47
  learned that lesson, but um, yeah, okay,
• 11:50
  so that's where we're at so far. Where do we
• 11:52
  go from here on the astrobiology
• 11:55
  train?
• 11:55
  Jonti Horner: Well, where we moved to in the latter part of
• 11:58
  the last astrobiology episode
• 12:00
  was my argument that
• 12:03
  you can't just look at a planet and say it's
• 12:05
  at the right temperature in the habitable
• 12:07
  zone. Um, we can look There. Whee.
• 12:10
  It kind of feels a bit like that when you
• 12:12
  read a lot of storeys, that the only
• 12:15
  consideration that comes into play is how far
• 12:16
  the planet is from its star. And I think
• 12:19
  instead, it's fairer to say that there are a
• 12:21
  huge variety of factors that can make
• 12:24
  one planet more or less suitable for the
• 12:27
  development of life and therefore for the
• 12:28
  observability of life on planets around other
• 12:31
  stars. And therefore, given that the
• 12:33
  observations to find life are going to be
• 12:35
  overwhelmingly the hardest we've ever had to
• 12:37
  carry out, we'll have hundreds, if not
• 12:40
  thousands of targets to choose from, but
• 12:41
  we'll only be able to look at a tiny handful
• 12:43
  of them in detail at first. So we need to be
• 12:46
  very careful about where we look. The
• 12:48
  proximity of the planet and its host star to
• 12:50
  the sun will be important because the closer
• 12:53
  the star is to a zombie we get for a given
• 12:55
  brightness of star, and also the more widely
• 12:58
  separated on the sky a star and planet will
• 13:00
  be for a given orbital distance between them.
• 13:02
  Closer they are, the more widely separated
• 13:04
  they are. And while people listening can't
• 13:06
  see this, I'm at the minute pointing fingers
• 13:08
  up at the side of my eyes to Andrew and then
• 13:10
  moving them towards the camera. Fingers are
• 13:12
  the same distance apart, but they get wider
• 13:14
  and wider apart on the screen as they get
• 13:15
  closer. Yeah. So there are clear reasons that
• 13:18
  we will look at stars that are nearer to
• 13:21
  us rather than further away. But beyond
• 13:23
  that, I think it's really important to
• 13:25
  consider all the different things that could
• 13:28
  factor in to make a given planet more
• 13:30
  suitable or less suitable for the
• 13:33
  development of life, and view them as like
• 13:36
  sliders on a mixing board in a sound studio,
• 13:39
  where you can fine tune things to see which
• 13:41
  gets the best sound, which gets the best
• 13:43
  score. You can rank your targets and
• 13:46
  you can start with the most promising ones,
• 13:48
  because with limited resources, you don't
• 13:50
  just want to do an unbiased survey, you want
• 13:52
  to instead maximise your chances of a
• 13:54
  positive result. Now, we're heavily biassed.
• 13:56
  We only know of one kind of life and that's
• 13:58
  Earth life. So we are very biassed towards
• 14:01
  looking for places that could support life
• 14:03
  like Earth life, because that's the only kind
• 14:05
  of life we do know exists that'll factor into
• 14:08
  it as well. But in the previous episode,
• 14:10
  towards the end, we talked about the way in
• 14:12
  which the location in the galaxy could
• 14:13
  potentially influence this, with the caveat,
• 14:16
  of course, that, uh, we're going to be
• 14:17
  looking at everything nearby. So whilst
• 14:19
  that's interesting scientifically, it's not
• 14:20
  that relevant. And then we also talked about
• 14:23
  the way that the nature of the stars that the
• 14:25
  planet orbits can influence things. And uh,
• 14:28
  not just from the point of view of is a star,
• 14:30
  ah, stable or single, but down to more subtle
• 14:32
  things like the fact that stars brighten over
• 14:35
  time. So just because a planet is in the
• 14:37
  habitable zone now doesn't mean it's been in
• 14:39
  that zone for long enough for life to become
• 14:42
  well established.
• 14:42
  So we talked about all that, where we
• 14:45
  finished up though we didn't get to my own
• 14:48
  personal favourite parts of the science and
• 14:50
  the stuff I'm more directly involved with,
• 14:52
  which are the more local influences on the
• 14:54
  planet, that is the influence of the
• 14:57
  planetary system in which that planet moves,
• 14:59
  all the other planets and all the debris
• 15:00
  therein, but also the impact of the planet
• 15:03
  itself, what it's made of, how it behaves.
• 15:06
  And there's a lot of subtlety in that that.
• 15:08
  When I prepared with my old mentor, Professor
• 15:10
  Barry Jones this review article on this 16
• 15:12
  years ago now, we dug into and it
• 15:15
  highlighted to me how none of these questions
• 15:18
  can be answered from people within a single
• 15:20
  research silo at all. You need researchers
• 15:23
  from all different disciplines of human
• 15:24
  experience, from the sciences, the biological
• 15:27
  sciences, physical sciences, geosciences,
• 15:29
  chemistry and astronomers all to come
• 15:31
  together. You probably also need philosophers
• 15:34
  and archaeologists to come into the
• 15:36
  discussion to talk about, about how we look
• 15:38
  and why we look and what we look for. And
• 15:40
  that's particularly true when we start moving
• 15:43
  from simple life to life that could talk
• 15:46
  back to us. And a very dear friend of mine in
• 15:48
  Australia who Fred Watson probably knows very
• 15:50
  well as well is Professor Alice Gorman down
• 15:52
  at Adelaide, who's a space archaeologist and
• 15:55
  has given some of the most astonishing and
• 15:57
  mind blowing talks I've ever seen from the
• 15:59
  point of view of someone who is trained in
• 16:01
  archaeology looking at the record of human
• 16:04
  space flight and what we should do to
• 16:06
  preserve artefacts like the Apollo landing
• 16:08
  site for future generations. Generations how
• 16:09
  we should consider that
• 16:13
  Andrew Dunkley: I absolutely agree because
• 16:16
  it was probably one of the
• 16:19
  greatest achievements in human history, if
• 16:21
  not the greatest achievement in human
• 16:23
  history. I mean inventing the wheel probably
• 16:25
  would have been a pretty cool thing too, but
• 16:27
  I don't know where that happened or when and
• 16:29
  they never would have thought to commemorate
• 16:31
  it. But um, it is something that
• 16:34
  should, should, you know, when we eventually
• 16:37
  have permanent residents on the moon,
• 16:39
  at least need to put a cyclone fence around
• 16:42
  it just for the time being until we can build
• 16:45
  a proper structure to protect
• 16:48
  it.
• 16:48
  Jonti Horner: Probably a good place to have rabbit proof
• 16:49
  fence because that will, that'll do the job.
• 16:52
  Andrew Dunkley: Um, yeah, well, you know that rabbits will
• 16:55
  ultimately be on the moon. They tend to be
• 16:57
  everywhere else.
• 16:58
  Jonti Horner: Um, now one of the greatest conference talks
• 17:00
  ever witnessed actually was a talk by a list
• 17:02
  talking about archaeology. And it was from
• 17:03
  the education and biases
• 17:06
  point of view. And I know this is already a
• 17:08
  bit off topic, but it's a storey I think
• 17:10
  really well worth repeating. Alice is an
• 17:12
  archaeologist and so she teaches archaeology
• 17:14
  students and she gave this talk about how she
• 17:16
  took a group of her uh, final year students
• 17:19
  to this site in Fairlie Regional New South
• 17:21
  Wales for a two day dig. Basically go out
• 17:24
  there, dig and come back to me with what you
• 17:25
  find and tell me about the storey of the
• 17:27
  site. And after two days all these
• 17:30
  young students came back and said, look, we
• 17:31
  didn't really find much, we found a few
• 17:33
  Aboriginal artefacts and that's kind of
• 17:35
  interesting, but all we found was a load of
• 17:37
  rubbish. We found all these blooming cable
• 17:38
  ties and bits of plastic that are polluting
• 17:40
  the site. What she then went on to do
• 17:43
  was the whole point was that the cable ties
• 17:46
  were actually the archaeology that she was
• 17:48
  interested in. So she went um, on and um,
• 17:50
  said in the talk that this was an old
• 17:52
  decommissioned listening station that had
• 17:54
  been built I think in like the late 1940s,
• 17:56
  post World War II, and operated into maybe
• 17:58
  the late 60s, early 70s before being
• 18:00
  demolished and removed. But by looking at the
• 18:03
  cable ties where they'd been identified had
• 18:05
  knowing a little bit about how cable ties and
• 18:08
  cable tie technology changed over the years,
• 18:10
  you could not only map out exactly where all
• 18:12
  the buildings had been and where the wire
• 18:14
  runs have been and get the structure of this
• 18:16
  long vanished building, you could also
• 18:19
  work out which bits were built when. And um,
• 18:22
  the whole importance here was partly that
• 18:24
  whole thing of one man's trash is another
• 18:25
  man's treasure, but it's also how
• 18:28
  as a scientist and a researcher, uh,
• 18:31
  you will miss things and you'll make mistakes
• 18:34
  because of your own personal biases that are
• 18:36
  quite often unconscious. And in this case for
• 18:39
  these students who've been studying
• 18:40
  archaeology, their unconscious bias was that
• 18:43
  anything modern is not archaeology. That's
• 18:46
  rubbish in the way of good archaeology. And
• 18:48
  so they totally miss the point. And it's a
• 18:50
  fabulous learning thing. It's why as
• 18:52
  scientists we use statistics so much. I know
• 18:54
  there's all this stuff about you can show
• 18:56
  anything with statistics, damn lies and
• 18:58
  statistics, all the rest of it. But
• 19:00
  fundamentally the reason that we use
• 19:01
  statistics as a tool school is because we as
• 19:04
  humans are biassed we've got this incredible
• 19:06
  evolutionary ability to see patterns when
• 19:09
  they're barely there, but we also have a very
• 19:11
  strong ability to see patterns that we expect
• 19:13
  to see when those patterns aren't actually
• 19:15
  there. And, um, that's certainly true of the
• 19:18
  canals on Mars. You know, Giovanni
• 19:20
  Schiaparelli saw these canals, these
• 19:23
  channels on, um, Mars, which I think the best
• 19:25
  explanation is that Mars was really bright.
• 19:27
  He had a big telescope and he was actually
• 19:29
  seeing the projection of his own capillaries
• 19:30
  in his eye, like I'm gonna see tomorrow when
• 19:33
  I get my eye test at the opticians and they
• 19:34
  do the bright light thing. But all these
• 19:37
  other observers with less good eyes and less
• 19:38
  good telescopes suddenly started seeing the
• 19:40
  canals. And it's this
• 19:43
  whole thing of when you're really straining
• 19:45
  at the limits of your vision, you see what
• 19:47
  you think you're going to see, not what there
• 19:48
  actually is. And that's true with our data.
• 19:51
  Uh, therefore, you use statistics
• 19:54
  to give you a feel for whether what you're
• 19:55
  seeing is significant or not, or whether it
• 19:57
  exists in the first place. And that's a way
• 20:00
  of us combating those biases. Now, that wasn'
• 20:03
  in that way to the archaeology students who
• 20:05
  thought that cable ties were rubbish, but it
• 20:07
  was a fabulous reminder of how we really
• 20:10
  need to be aware not only of the explicit
• 20:12
  biases, which are the things we choose to do.
• 20:15
  If they're doing a survey of people on hair
• 20:18
  loss and they say we interviewed men between
• 20:20
  18 and 30, that's clearly biassed to
• 20:23
  be for men between 18 and 30, not for men of
• 20:25
  our age, for example. That's an explicit
• 20:27
  bias, it's one that's a conscious choice.
• 20:29
  Implicit biases are the sneaky ones, where
• 20:31
  you don't realise you're making them. And
• 20:33
  that's why I've made it so clear up front
• 20:35
  here that we can imagine
• 20:38
  all kinds of life. Science fiction does it
• 20:40
  wonderfully, but our implicit bias is that,
• 20:43
  uh, when we talk about the search for life,
• 20:44
  at least in the very short term, we're
• 20:46
  actually looking for life like us, not you
• 20:49
  and I, but lifelike Earth, uh, life based on
• 20:51
  a planet with oceans, living on the surface,
• 20:54
  modifying the atmosphere, because that's the
• 20:56
  one kind of life we know exists, but also
• 20:58
  because that's the one kind of life we could
• 21:00
  probably identify with our observations. Life
• 21:02
  beneath the ice on Europa is fascinating, but
• 21:05
  we can't see it in the solar system. We
• 21:07
  wouldn't have a prayer if Europa was found
• 21:09
  orbiting another star, because the ice is in
• 21:11
  the way life on a surface that modifies an
• 21:14
  atmosphere is at least something we
• 21:16
  theoretically could detect. So that's making
• 21:18
  the implicit explicit.
• 21:21
  Andrew Dunkley: Gotcha. All right, we're gonna take a breath,
• 21:24
  uh, and get back to Astrobiology Part 2
• 21:27
  on Space Nuts.
• 21:30
  Let's take a little break from the to tell
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  you about online, uh, security with our
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  Jonti Horner: 3, 2, 1
• 23:50
  space nuts.
• 23:51
  Andrew Dunkley: And you're with Andrew Dunkley and Professor
• 23:54
  Jonty Horner okay, what next,
• 23:57
  Jonty, in this search for
• 23:59
  extraterrestrial life?
• 24:01
  Jonti Horner: Well, I think we come back to moving away
• 24:03
  from the diversions of archaeology and stuff
• 24:05
  to the factors that could make a planet more
• 24:08
  or less suitable as a target. And like I
• 24:11
  said, we talked about the galaxy, we talked
• 24:12
  about the stars. To me, as a person who
• 24:15
  comes originally from a solar system
• 24:16
  background, particularly fascinated with
• 24:18
  comets and asteroids and stuff like that,
• 24:21
  there are a lot of factors that have been
• 24:23
  proposed that relate to
• 24:26
  the interaction of planets and the
• 24:28
  interaction with the debris that's around
• 24:30
  that could render planets more or less
• 24:32
  suitable as targets. Now one
• 24:35
  example of this is the stability of orbits.
• 24:37
  You know, there are a variety of different
• 24:40
  models of the solar system's youth, some of
• 24:42
  which suggest that there were periods of
• 24:44
  chaotic instability where the planets orbits
• 24:46
  got stirred up, planets maybe even swapped
• 24:49
  orbits. Now this is the kind of thing we can
• 24:51
  model. And when we discover planetary
• 24:53
  systems, we can take the planets that we
• 24:56
  think are there and put them into computer
• 24:58
  software to run their orbits forward and back
• 25:00
  in time to see how they behave. And that's
• 25:03
  actually part of my day to day work. That's
• 25:05
  the technology I use and lots of tools I've
• 25:08
  used in the past to kill planetary systems
• 25:10
  that people thought were there because I run
• 25:12
  simulations and showed they're simply not
• 25:14
  stable on very short timescales.
• 25:17
  But on longer time scales, these kind of
• 25:18
  perturbations can have a significant impact
• 25:22
  on the orbits of planets. You can get
• 25:24
  significant shifts over time. You can get
• 25:27
  encounters and stirring up, which means
• 25:29
  sometimes that a planet will be on an orbit
• 25:32
  now that is not the orbit it's occupied in
• 25:34
  the past. And uh, those are things that we
• 25:37
  could probably pull out, tease out from the
• 25:38
  simulation kind of work that I do. And
• 25:40
  obviously a planet that is now in the
• 25:43
  habitable zone, um, but that was previously
• 25:45
  well outside it would not be a good place to
• 25:47
  look. Even though it looks good now, it's not
• 25:50
  great. It's like, I guess, you know, you've
• 25:52
  got two petri dishes in front of you that you
• 25:54
  could look at for life, but you can tell that
• 25:56
  one of them's been absolutely melted in a
• 25:58
  fire. It's at room temperature now, but that
• 26:00
  doesn't mean it always has been that same
• 26:02
  kind of idea. So that on a coarse scale has
• 26:04
  an effect. But there's a subtler version of
• 26:06
  that that I've done a little bit of work on
• 26:08
  in the past. And I've got a PhD student
• 26:10
  working with me at the moment minute, who's
• 26:12
  going to look into this a lot more. A
• 26:13
  wonderful student called Amber Tilly. It's
• 26:16
  the idea of the Milankovitch cycles.
• 26:19
  Now, on Earth, we
• 26:22
  look at climate change in the short term as
• 26:24
  being a big problem because it's a very rapid
• 26:26
  change that is being caused by human action.
• 26:29
  But on much longer timescales, the climate of
• 26:32
  Earth is periodically variable. We've had ice
• 26:34
  ages and interglacial periods for the last 2
• 26:37
  or 3 million years, which are the direct
• 26:39
  result of the subtle nudges and tweaks on
• 26:42
  the, uh, Earth from all the other objects in
• 26:44
  the solar system, primarily the other
• 26:46
  planets, and not mainly Jupiter to be honest.
• 26:48
  But most of the planets contribute. These are
• 26:51
  called the Milankovitch cycles. They have a
• 26:54
  number of effects. Firstly, the Earth on its
• 26:56
  axis precesses. It wobbles with a period of
• 26:59
  about 23,000 years. So our polar
• 27:02
  axis, which is tilted by currently 23 and a
• 27:04
  half degrees to the plane of our orbit,
• 27:07
  wobbles around like a kid's wobbly spinning
• 27:09
  toy coming to a stop. It precesses, wobbles
• 27:12
  around a bit like the thing in Inception
• 27:13
  about to fall over. You see this procession?
• 27:16
  That's a procession of the equinoxes. That's
• 27:18
  why your horoscopes are wrong. While it's one
• 27:20
  of the many reasons that your horoscopes are
• 27:22
  wrong, but it's particularly why your
• 27:23
  horoscopes are out by one particular one
• 27:26
  full calendar month. Because the
• 27:29
  horoscopes are based on where the sun is, was
• 27:31
  in the sky at that date 2,000 years ago.
• 27:35
  And, um, the axis of the Earth has wobbled
• 27:37
  round, so it's now one constellation round.
• 27:39
  So when the sun is in Aries, according to
• 27:42
  your horoscope, it's actually now in Pisces,
• 27:45
  all because of the wobble. That wobble takes
• 27:47
  23,000 years to complete. That means that
• 27:50
  the direction that the Earth is pointing
• 27:52
  changes over time. Essentially. Added
• 27:55
  to that, you've got a very slight wobble up
• 27:57
  and down where the tilt fire axis, which is
• 27:59
  currently 23 and a half degrees, changes from
• 28:02
  about 22 to, to 24 degrees, rocking back and
• 28:04
  forward. So that causes the size of the
• 28:07
  Arctic and Antarctic circles to grow and
• 28:09
  shrink very slightly. On um, top of all that,
• 28:12
  you've then got the Earth's orbit around the
• 28:13
  sun flexing and tilting. Its shape
• 28:16
  becomes more circular and more elongated,
• 28:19
  more eccentric. With a longer period period,
• 28:21
  I think about 100,000 years, something like
• 28:23
  that, our orbit, compared to the orbits of
• 28:26
  Jupiter and Saturn, tilts a little bit up and
• 28:28
  down the inclination changes, which adds to
• 28:31
  the change of the tilt in our spin axis a
• 28:33
  little bit. We also have the Earth's orbit
• 28:36
  precessing around in just the same way our
• 28:37
  poles do, and that's a little bit harder to
• 28:39
  visualise. But what that means is that the
• 28:42
  direction, if you drew a line from the sun
• 28:45
  through the Earth and out into space at, ah,
• 28:47
  the point the Earth was at perihelion closest
• 28:49
  to the sun, that direction will
• 28:52
  gradually move round over time, doing a full
• 28:54
  lap with a period of several tens of
• 28:56
  thousands of years. So our perihelion
• 28:58
  possession processes as well, all of the,
• 29:01
  that combined means that, uh,
• 29:04
  on average the amount of energy reaching the
• 29:06
  Earth's polar regions, averaged over a given
• 29:08
  year, varies with type. Sometimes the
• 29:11
  poles get a bit more energy and the ice
• 29:14
  sheets retreat. Sometimes they get a bit less
• 29:16
  energy and the ice sheets come back towards
• 29:18
  the equator again. Now, there's a lot of
• 29:20
  complex feedback from the Earth because ice
• 29:22
  is more reflective than water or land. So
• 29:24
  when ice is growing, it has a tendency to
• 29:26
  keep growing, and when it's shrinking, that
• 29:29
  has a tendency to run away as well. So you've
• 29:31
  got all these different feedbacks. But what
• 29:33
  that means is that on the Earth we've got
• 29:35
  these periodic variations in the
• 29:38
  amount of energy at the poles which lead to
• 29:40
  periodic glaciations and interglacial
• 29:42
  periods. That's the Milankovitch cycles.
• 29:45
  It means that on timescales of tens of
• 29:47
  thousands of years, our climate is relatively
• 29:49
  changeable. What would
• 29:52
  happen if the planets were on different
• 29:54
  orbits or if you were in a
• 29:57
  planetary system with a totally different
• 29:59
  architecture? The result would be very
• 30:01
  different Milankovitch cycles. You'd have
• 30:04
  different periods and you'd also have
• 30:06
  different amplitudes. You could imagine
• 30:08
  scenarios where instead of our Earth rocking
• 30:10
  a little bit from 22 to 24 degrees and back
• 30:13
  with its polar axis, it could be like Mars,
• 30:16
  whose spin axis varies chaotically, can even
• 30:18
  tip over on its side. You could have systems
• 30:21
  where there's barely any change whatsoever.
• 30:23
  You've got this full gap. Now the beauty is,
• 30:25
  again, we've got the tools to test this.
• 30:28
  We can run the kind of computational
• 30:30
  simulations that I've spent my career doing
• 30:33
  and, uh, model the orbits of a planet over
• 30:35
  time under the influence of all the other
• 30:36
  planets. And I did a lot of simulations of
• 30:39
  this between 2012 and 2020. I
• 30:42
  kept coming back to the idea, but never got
• 30:44
  around to publishing it until we got to 2020,
• 30:46
  where I published it with, um, Stephen Cain
• 30:49
  from University of California, Riverside. Pam
• 30:51
  Vervoort, who was his PhD student at the
• 30:53
  time, a couple of other people, people where
• 30:55
  we said, what is the influence of Jupiter on
• 30:58
  our Milankovitch cycles? What would happen if
• 31:00
  you move Jupiter closer to the sun or further
• 31:02
  away? If you made Jupiter's
• 31:04
  orbit more eccentric or less eccentric, how
• 31:07
  would that change the period and, um,
• 31:09
  amplitude of the Earth's? Milankovic cycles
• 31:12
  did the test. And in many cases, moving
• 31:14
  Jupiter destroyed the solar system, which
• 31:16
  meant the Earth wouldn't be here, which was
• 31:18
  kind of fun, but not very helpful. But for
• 31:21
  the versions of the solar system where the,
• 31:23
  the Earth was not removed, we got to see
• 31:26
  the range, the variety of Milankovitch cycles
• 31:28
  we would have from moving Jupiter in a bit
• 31:31
  closer or moving it a bit further away. And
• 31:33
  for those really interested, we moved Jupiter
• 31:34
  in as far as 3 Au from the sun, out as far as
• 31:37
  7 Au from the sun, where 5 Au is about where
• 31:40
  it is at the minute, 5.2. What we
• 31:42
  found, which is quite surprising, is that the
• 31:44
  Earth's, uh, Milankovitch cycles are neither
• 31:47
  unusually big or unusually small. They're
• 31:49
  somewhere in the middle. Middle. Which is a
• 31:50
  bit of an argument against a hypothesis
• 31:52
  called the Rare Earth hypothesis.
• 31:55
  This idea has been around for about 20, 25,
• 31:58
  30 years, and I've never really liked it.
• 32:01
  It's the idea that life on Earth is such a
• 32:04
  remarkable, incredible fluke
• 32:07
  that we will never find life elsewhere. And
• 32:09
  the authors put forward all these
• 32:11
  peculiarities about the Earth, uh, and argue
• 32:13
  that without them we would not be here.
• 32:16
  And it's a bit of a philosophical thing, but
• 32:19
  I think it's very dangerous to look at
• 32:21
  somewhere that has life and say, this place
• 32:23
  has all these unusual things and they are
• 32:25
  therefore required for life because we've
• 32:27
  never found life elsewhere. A good example is
• 32:29
  the presence of a large moon. And we'll talk
• 32:31
  about this a bit more later on. We have life
• 32:33
  on Earth and we have a big moon, so it's
• 32:35
  natural to think you need a big moon to have
• 32:37
  life. But we won't know that until we find
• 32:39
  life elsewhere. But that led to this argument
• 32:42
  of rare Earth life will be uncommon in the
• 32:44
  universe. If rare Earth were true,
• 32:47
  then when you look at something like the
• 32:48
  Milankovitch cycles, you would expect our
• 32:50
  Earth to be unusual in some way,
• 32:54
  to have conditions that favour life over your
• 32:56
  typical system. And we simply don't find that
• 32:59
  our Milankovitch cycles are fairly run of the
• 33:01
  mill. They're not big, they're not small,
• 33:03
  they're not fast. They're not slow, they're
• 33:06
  somewhere in the middle. Now,
• 33:08
  um, sorry, Pam went with that. Pam lava vault
• 33:11
  was.
• 33:11
  She then took the output of that and run it
• 33:13
  into climate modelling software, which was
• 33:15
  fabulous. And she published that work, work
• 33:17
  with us in 2022, where
• 33:20
  she was able to link the Milankovitch cycles.
• 33:22
  We predicted if you moved Jupiter around
• 33:25
  with the amplitude and frequency of the
• 33:28
  ice ages, we'd get. And it was really
• 33:29
  interesting because it turned out that when
• 33:31
  you factor in some of the feedback mechanisms
• 33:33
  that are in climate modelling, you actually
• 33:35
  could change the Earth's Milkovitch cycles a
• 33:37
  little bit and get very drastically different
• 33:39
  ice ages, much more frequent and shallower,
• 33:42
  or much less frequent and deeper just by
• 33:45
  small changes. Now, now, it's all
• 33:47
  fascinating just from the solar system point
• 33:49
  of view, but what we're really doing is we're
• 33:51
  putting down tools that when we find
• 33:54
  planets that could be suitable, we can do
• 33:56
  these same tests. We can look at them and
• 33:58
  say, we're thinking that you might be a
• 34:00
  target for life. Let's see what your
• 34:02
  Melankovic cycles are like. Let's see how
• 34:04
  stable your climate is. And if we find
• 34:06
  somewhere that flops between snowball Earth
• 34:09
  and a hothouse every 10 years, or that has
• 34:12
  incredibly long snowball Earth periods
• 34:13
  followed by short periods of temperate
• 34:15
  climate climate, even though everything else
• 34:18
  looks good, that's probably not as, uh,
• 34:19
  suitable for life as somewhere that is
• 34:21
  temperate all the time. So we can use that as
• 34:24
  a bit of a filter. And that's where the new
• 34:26
  PhD student we've got, Amber Tilly, comes in.
• 34:28
  Amber's, um, going to be doing the same kind
• 34:30
  of work, moving it forward, where she's going
• 34:32
  to be looking at a whole slew of different
• 34:33
  parameters to see how the
• 34:36
  Milankovitch cycles change as you vary
• 34:39
  things. She's both going to look at what
• 34:41
  would happen if the Earth was a bit more
• 34:42
  massive or less massive. How would that
• 34:44
  change things? Because of the feedback, you
• 34:46
  make Earth more massive, it interacts,
• 34:48
  interacts more with other things, stirs them
• 34:49
  up, you get a feedback there. She's also
• 34:52
  going to look, working with colleagues of
• 34:54
  ours overseas, at, uh, models of planet
• 34:57
  formation that form planetary systems similar
• 34:59
  to the solar system as theoretical
• 35:02
  data, and say, what would the Milankovitch
• 35:04
  cycles be like in this hypothetical system?
• 35:07
  So it's not just a purely hypothetical
• 35:09
  question, it's something we can actually dig
• 35:10
  into and, um, we can test. And I think
• 35:13
  that's fundamental to science. It's no good
• 35:15
  just arguing something you want to be able to
• 35:16
  Test. Test it.
• 35:18
  Andrew Dunkley: Yeah. I suppose what you're suggesting is
• 35:21
  that by mucking around with
• 35:24
  what we know and making slight alterations,
• 35:27
  it gives you an idea of what to look
• 35:30
  for going forward in identifying
• 35:33
  potential targets.
• 35:34
  Jonti Horner: Absolutely. And it's good because one of the
• 35:37
  reasons that you'd want to use the Earth is
• 35:39
  because we've got a ground truth. You can run
• 35:41
  the Earth with the current solar system
• 35:43
  parameters and put them into a climate model.
• 35:45
  And you should get what we see so we can
• 35:47
  ground truth it, which is really, really
• 35:49
  important. And, um, that is, I think, one of
• 35:51
  the main, most obvious ways where even in a
• 35:54
  dynamically stable system, a system that
• 35:56
  isn't tearing itself apart, interaction
• 35:58
  between planets could have a significant
• 36:00
  impact on habitability. And we want to look
• 36:03
  into it. It's really, really fascinating.
• 36:06
  Andrew Dunkley: Indeed it is. All right, um, we
• 36:08
  are talking astrobiology on this
• 36:11
  special episode of Space Nuts with Professor
• 36:14
  Jonty Horner.
• 36:15
  Back in.
• 36:19
  Okay, we checked all four systems and
• 36:21
  Jonti Horner: being with a go, space nets.
• 36:23
  Andrew Dunkley: Jody, I thought we might just start off
• 36:25
  this, uh, final segment with a
• 36:28
  question from the audience. Uh, it's funny
• 36:30
  because this question's come in before any of
• 36:33
  these astrobiology episodes have
• 36:36
  been released. And yet it's
• 36:39
  exactly what we've been talking about. This
• 36:41
  comes from Chris.
• 36:42
  Jonti Horner: Hi, um, I'm Chris from Axmouth in the uk.
• 36:46
  I'd, uh, just like to ask, um, given that
• 36:48
  interstellar travel to distance solar systems
• 36:50
  is likely to remain impractical for humans,
• 36:53
  um, do you think a more realistic long term
• 36:55
  strategy would be to
• 36:57
  Andrew Dunkley: seed the galaxy with the basic building
• 36:58
  blocks of life? Uh, for example,
• 37:01
  uh, sending autonomous probes carrying
• 37:04
  microbes or prebiotic material that could
• 37:06
  Jonti Horner: eventually take hold on suitable planets,
• 37:08
  even
• 37:09
  Andrew Dunkley: if that process takes thousands or millions
• 37:11
  of years.
• 37:12
  Jonti Horner: Thanks.
• 37:14
  Andrew Dunkley: There's a, uh, thought from Chris. So
• 37:17
  he's probably suggesting, you know, could we
• 37:19
  seed other planets? Uh, would that be
• 37:22
  the way to go? Uh, and autonomous,
• 37:25
  uh, vehicles. I think last
• 37:27
  time we talked about this a couple of
• 37:29
  episodes ago, you, you suggested it's,
• 37:32
  it's beyond us to actually
• 37:34
  send a human mission to another world
• 37:37
  to investigate life. But we could
• 37:41
  go the way of autonomous vehicles.
• 37:44
  Uh, but for the major
• 37:47
  distances, like the impossible distances, uh,
• 37:50
  we would have to come up with equipment in
• 37:53
  the future that could do it from a
• 37:56
  stable environment nearby. Um,
• 37:59
  I don't know how you want to tackle that
• 38:00
  question.
• 38:01
  Jonti Horner: There's a fair bit to it, and I mean, it
• 38:02
  reminds me of the wonderful Bobbyverse books
• 38:05
  that I've quite enjoyed. You know, um, the
• 38:07
  Storey of the Self Intelligent Von Neumann
• 38:09
  probes, which are, uh, easy listening and
• 38:11
  work very well as audiobooks.
• 38:14
  It's a challenging one. So we could
• 38:17
  do this. It would be feasible.
• 38:20
  The question would become whether it's
• 38:22
  ethical and right. Yes, and that's a really
• 38:25
  challenging one. Now, there is something that
• 38:27
  costs research missions
• 38:30
  a vast amount of money called planetary
• 38:32
  protection. And it's the idea that if we're
• 38:35
  sending a spacecraft that has a possibility
• 38:37
  of touching down on a place where we are
• 38:40
  currently interested in looking for life,
• 38:42
  where there could be life, such as Mars, such
• 38:45
  as Europa, uh, Ganymede, Titan, around
• 38:48
  Saturn. We don't want to take life with
• 38:50
  us because you don't want to find life on
• 38:52
  Mars only to discover it's what you took with
• 38:54
  you. And also we don't want to pollute or
• 38:56
  contaminate those environments. So there's a
• 38:59
  huge amount of effort and expense, goes into
• 39:02
  extreme sterilisation of spacecraft to kind
• 39:04
  of prevent exactly the hypothesis being
• 39:06
  discussed here. At the same time,
• 39:09
  that idea of populating the galaxy with
• 39:12
  simple life that could one day grow
• 39:15
  to resemblers or something else has
• 39:18
  cropped a few times in science fiction. I
• 39:20
  believe that was how Star Trek got
• 39:23
  around the fact that all of their humanoid
• 39:25
  species looked like people with makeup on.
• 39:28
  Um, which of course is a budgetary issue and
• 39:30
  a special effects issue. But they had an
• 39:32
  episode where people found the founders,
• 39:34
  which were an alien, ancient alien humanoid
• 39:37
  race at seed of the galaxy. And billions of
• 39:39
  years later all these different planets had
• 39:41
  grown humanoids that looked like them and.
• 39:43
  Oh, well, convenient job done. Stop asking us
• 39:46
  that question now, please. Effectively it
• 39:48
  is something we could do and the timescales
• 39:51
  would be immense. It's also something that,
• 39:53
  in all honesty, has already happened. There's
• 39:55
  this idea called panspermia, which is the
• 39:58
  idea that life could be transferred through
• 40:00
  space from planet to planet, carried by
• 40:02
  debris from impacts and talking. Thirty or
• 40:05
  40 years ago, it was viewed as very much
• 40:07
  crank science, not feasible. But every
• 40:09
  experiment that people have ever done
• 40:11
  suggests that it could work. And I've even
• 40:13
  had a PhD student just submit his thesis,
• 40:16
  Greg Davis, who has been looking at this
• 40:19
  from the point of view of the viability of
• 40:20
  bacteria transferred from Earth to Mars or
• 40:23
  Mars to Earth in the radiation environment in
• 40:26
  the solar system. And it seems to work.
• 40:29
  Now, to me, the fact that biological, uh,
• 40:32
  material from Earth will have rained down on
• 40:34
  Mars and Europa and Ganymede and everywhere
• 40:36
  else for the last 4 billion years
• 40:39
  probably means that we're being a bit over
• 40:40
  cautious with our planet protection efforts
• 40:43
  because we're trying not to take something
• 40:45
  there when it's already there, it's already
• 40:47
  been delivered. The other thing is that
• 40:49
  anything we take with us to a place that has
• 40:51
  an incredibly, incredibly different
• 40:52
  environment, if there is life there already,
• 40:55
  that life should hugely outcompete anything
• 40:57
  we take with us because it's better adapted
• 40:59
  for that environment. And that would be one
• 41:01
  of the challenges with this, is sending stuff
• 41:03
  out. It'd have to be lucky to get exactly the
• 41:05
  right environment to grow. But with the
• 41:06
  amount of real estate we've got out there it
• 41:09
  could happen. People have even in some more
• 41:12
  extreme sci fi suggested kind of
• 41:15
  this type approach as a way to
• 41:18
  begin terraforming planets ahead of human
• 41:20
  arrival. This idea that you could send
• 41:21
  generation ships which have to go
• 41:24
  slowly because they're really big and carry a
• 41:26
  lot of people. But you could send faster
• 41:28
  moving, smaller things first to start
• 41:31
  working on the biosphere of a planet to make
• 41:33
  it so that when we get there that planet is a
• 41:35
  suitable home. So there's a lot of ways it
• 41:37
  could be taken. Taken. I think to do it
• 41:40
  in the near future in an official organised
• 41:42
  way would require a significant shift in
• 41:44
  global morality in the way we think about
• 41:47
  other habitats. If we found that
• 41:49
  Mars absolutely has no life and
• 41:52
  possibly that it never had life, which I
• 41:54
  think is probably unlikely, then I could see
• 41:56
  people arguing then for terraforming.
• 41:58
  Similarly people have argued about, I think
• 42:00
  Carl Sagan suggested this, creating
• 42:03
  engineering bacteria that could float in the
• 42:06
  clouds of Venus and um, precipitate out the
• 42:08
  carbon to eventually make Venus a more
• 42:11
  habitable planet on long timescales. The idea
• 42:13
  of terraforming these worlds is real. But I
• 42:15
  think it would require either a state
• 42:18
  to go its own way because as we know, once
• 42:21
  things are up in space, ain't nobody going to
• 42:22
  stop you. Uh, as was the case with the
• 42:24
  Israeli spacecraft that spattered tamigards,
• 42:27
  um, water bears over the moon to show that
• 42:29
  they could, which was so dumb it's untrue.
• 42:33
  Um, yep, there are water bears on the moon,
• 42:36
  probably desiccated and dried up, but they
• 42:38
  can come back from that, we know that. Um, so
• 42:40
  you could have a nation just decide to do it
• 42:42
  anyway. At the end of the day, if a
• 42:44
  random government decided to send a
• 42:46
  spacecraft to Mars within a capsule inside
• 42:49
  laden with biological bacterial life
• 42:52
  to spurt out on the surface, no way we could
• 42:55
  stop them. And once it's done, it's done. Um,
• 42:57
  but I think the block to the question is not
• 43:00
  actually a scientific one, it's an ethical
• 43:02
  one and it's about how we, we choose to
• 43:04
  interact with the galaxy going forward and
• 43:06
  particularly our local environment. That'll
• 43:08
  determine at what stage we do that, if we
• 43:10
  ever do so. It's a really good question.
• 43:12
  Andrew Dunkley: It is. Uh, thanks for the uh, question,
• 43:14
  Chris. Uh, Chris, you might be interested to
• 43:16
  look up the BBC radio science
• 43:19
  fiction comedy called Paradise Lost in Space.
• 43:22
  Have you heard of this one? It's so funny.
• 43:24
  It's about two blokes who um, get ejected
• 43:28
  from a spaceship by an exploding toilet or
• 43:30
  something and they end up on a world that's
• 43:32
  occupied by uh, an insect, intelligent but
• 43:35
  very naive species. So
• 43:38
  basically what they do is they try to
• 43:41
  pass on their Earth knowledge and
• 43:44
  intelligence to these, these people
• 43:46
  and ultimately destroy the planet.
• 43:50
  Jonti Horner: It's a perfect reflection.
• 43:51
  Andrew Dunkley: Brilliant.
• 43:52
  Jonti Horner: It's very funny. Yes.
• 43:55
  Andrew Dunkley: Yeah, it's funny stuff. So yeah, it's called
• 43:58
  um, Paradise Lost in Space. I
• 44:01
  only remember it because we ran it as a
• 44:03
  series on the ABC some years ago and, and got
• 44:05
  a uh, fabulous response. And I always,
• 44:08
  I sat there in the studio while we were
• 44:10
  running it and I just cackled as to. Because
• 44:13
  I could imagine that's what we might do.
• 44:16
  Not on purpose, but um. Yeah. And it's what
• 44:19
  you say, it's the ethics of sending
• 44:23
  our ah, junk to other places that are already
• 44:26
  occupied. Yeah. Um,
• 44:29
  we're running out of time I suppose. But um,
• 44:32
  how do you want to wind this up? Uh, how do
• 44:33
  you.
• 44:34
  There's so much to talk about, it could go on
• 44:36
  for hours.
• 44:36
  Jonti Horner: I know more to talk about. I think I'll carry
• 44:38
  on until you kind of get the hook and pull me
• 44:41
  off about the different things that influence
• 44:43
  planet's habitability. Because we've talked
• 44:45
  about Milankovitch cycles. We also have as
• 44:48
  the influence of the planetary system impact
• 44:50
  us just as the dinosaurs, they had a very bad
• 44:53
  day. And there has historically been this
• 44:55
  idea that ties into the rare Earth thing that
• 44:57
  Jupiter is our friend and saviour and without
• 45:00
  Jupiter we'd be hit by asteroids more often
• 45:02
  and we wouldn't be here. And therefore life
• 45:04
  is rare in the universe. Um, idea
• 45:07
  basically that Jupiter is our bestest friend
• 45:09
  and it's honestly a lot of cobs wallop and
• 45:12
  it's both one of my favourite bits of
• 45:15
  research I ever did. And probably one of the
• 45:16
  biggest bugbears of my career is uh, I
• 45:19
  did work again with Barry Jones starting 20
• 45:22
  years ago for a few years that resulted in a
• 45:24
  series of pep called Jupiter Friend or Foe.
• 45:27
  And we did simulations to test the role of
• 45:29
  Jupiter in protecting us from impacts or not.
• 45:32
  And it turns out that Jupiter is not shielded
• 45:35
  all if you took Jupiter away, Earth would be
• 45:37
  hit less often. If however you
• 45:40
  replace Jupiter with a planet, the mass of
• 45:42
  Saturn, Earth would be hit more often than we
• 45:45
  are today. And with Jupiter, the mass it
• 45:47
  currently is, we'd be hit more than if it
• 45:49
  wasn't there, but less than if we put Saturn
• 45:50
  there. All down to the subtleties of how
• 45:53
  gravity all works. And so basically if you
• 45:55
  replace Jupiter with Saturn, it's like the
• 45:57
  anti Goldilocks case where you've lesser
• 45:59
  porridge with strychnine. But the reality is
• 46:01
  that Jupiter's role is complicated,
• 46:05
  best illustrated by Comet Lexell in
• 46:07
  1770, which I always love. Comet Lexell was
• 46:11
  a great comet. It was very bright in our sky.
• 46:13
  Discovered by Charles Messier I think 1st of
• 46:15
  June 1770. Quickly got as
• 46:18
  bright as the brightest stars in the sky, but
• 46:19
  looked unusual. It was very big and fuzzy and
• 46:22
  it moved unusually rapidly across the sky at
• 46:24
  its quickest, covering 42 degrees in a single
• 46:26
  hour. When they worked out the orbit of this
• 46:29
  thing, they found a that it had come very
• 46:31
  close to the Earth. It passed within 2
• 46:32
  million kilometres, which is the close
• 46:34
  closest approach of a large comet in
• 46:37
  historical times. It also was moving
• 46:40
  on an orbit that was just less than six years
• 46:41
  in period. Big bright comet going around
• 46:44
  every six years. Why on Earth have we not
• 46:46
  seen it before? Why have we not seen it in
• 46:47
  1764 or 1758? Well,
• 46:50
  when they worked out the orbit and run it
• 46:52
  back in time and this was hard at the time
• 46:54
  because they didn't have mechanical
• 46:56
  computers, they had human computers who sat
• 46:58
  there and did calculations with abakai and
• 47:00
  slide rules and all the rest of it. They
• 47:02
  found that three years before it nearly hit
• 47:04
  the Earth it was very close to Jupiter. In
• 47:07
  fact, prior to that it had been moving on an
• 47:08
  orbit that came nowhere near the Earth, that
• 47:11
  was probably hundreds or thousands of years
• 47:12
  in period and it was flying in to come
• 47:15
  nowhere near the inner solar system. When it
• 47:16
  had this close encounter with Jupiter that
• 47:18
  trapped it and threw it at the Earth and
• 47:20
  captured it onto the six year long Jupiter
• 47:22
  family comet orbit. So Jupiter took something
• 47:25
  that was coming nowhere near us and threw it
• 47:27
  out at us. We don't see the comet
• 47:30
  anymore because 2 times 6 years is
• 47:33
  12 years and Jupiter takes 12 years to go
• 47:34
  around the sun. So the comet did two laps in
• 47:37
  the time Jupiter took to take one. And when
• 47:39
  the comet got back out there again 12 years
• 47:42
  after the first encounter, Jupiter was there,
• 47:44
  grabbed hold of it and threw it away again,
• 47:45
  never to return. So in just this 12 year
• 47:48
  period, Jupiter threw something at us and
• 47:51
  then cleaned up after itself. And whether
• 47:53
  Jupiter's more of a shield or more of a
• 47:55
  threat is down to the balance of those two
• 47:56
  effects. Um, and what we found in our
• 47:59
  simulations is, to be honest with Jupiter, we
• 48:02
  get hit more than we would do if it wasn't
• 48:03
  there. That takes away the idea
• 48:06
  that it's our protector. It takes away the
• 48:09
  idea that you need a shield to shield a
• 48:11
  planet to prevent life from being wiped out.
• 48:14
  Another nail in the coffin of rare Earth. And
• 48:17
  it bugs me a bit that so many documentaries
• 48:19
  still trot out this trite idea that Jupiter
• 48:22
  shields us from impacts. And it's wonderful
• 48:24
  because I disprove that 20 years ago. It's
• 48:27
  much more complicated. But even that idea
• 48:29
  gets complicated because obviously we don't
• 48:31
  want to have the Earth punishingly, uh,
• 48:33
  pummelling because we'd be wiped out. But
• 48:36
  where the Earth formed in the solar system,
• 48:37
  it probably formed dry. We formed interior to
• 48:40
  the location of the ice line. So there wasn't
• 48:42
  any available solid water, the water was all
• 48:45
  gas. So how the Earth got its water was a
• 48:47
  long, outstanding problem, exacerbated by the
• 48:50
  fact that towards the end of our planet's
• 48:52
  formation, we got smashed into by an object
• 48:53
  the size of Mars, which stripped off a lot of
• 48:56
  the Earth's core and mantle and would have
• 48:57
  desiccated our planet because m water would
• 48:59
  have been in the. Or a mantle, in the crust
• 49:01
  and mantle. Sorry, up near the surface. Yeah.
• 49:04
  So where did the water come from? And Earth
• 49:06
  is actually a remarkably dry planet, um,
• 49:08
  particularly at the moment in Queensland. The
• 49:10
  idea is down here. Yeah, the idea is that our
• 49:13
  water, at least in significant part, was
• 49:15
  delivered from further out by impacts in what
• 49:18
  is often described as a late veneer.
• 49:21
  That's really interesting air because that's
• 49:23
  a stochastic process, it's random, it's
• 49:25
  driven by the orbits of the planets and the
• 49:27
  cleanup phase of solar system formation.
• 49:29
  So different planetary systems will give
• 49:31
  planets with different amounts of water. But
• 49:34
  it's also indicating that you actually don't
• 49:36
  want too much shielding, you need
• 49:38
  impacts. Because if the Earth had never had
• 49:40
  the impacts, we'd have never got enough water
• 49:42
  for life to develop and thrive. On top of
• 49:45
  that, if the Earth didn't have enough
• 49:46
  impacts, the dinosaurs would never have been
• 49:48
  wiped out. And maybe you and I will be
• 49:50
  reptiles or maybe we'll be here, you know,
• 49:53
  so there's a whole aspect of that. Now,
• 49:55
  again, those Simulations I did, we can
• 49:58
  rerun through the planetary systems, we can
• 50:00
  find the debris belts in those systems, we
• 50:02
  can find the planets so we can model their
• 50:04
  impact rates. And I'd argue that we want to
• 50:06
  look somewhere that doesn't have too many
• 50:08
  impacts, but also doesn't have too few,
• 50:11
  because each of those could pose problems.
• 50:14
  That is a really big part of the storey
• 50:17
  and it feeds into the last point, really,
• 50:21
  which is the planet itself and a little bit
• 50:23
  tied to the large moon. So our Earth, it has
• 50:26
  been suggested again by the rare Earth crowd,
• 50:28
  that the large moon we have stabilises our
• 50:31
  atmosphere axis and has kept the Earth
• 50:33
  habitable. So therefore you need a giant
• 50:35
  satellite. But simulations by Dave
• 50:38
  Waltham, who's a guy I know very well in the
• 50:40
  uk, looked into this and what he found was
• 50:42
  that you could take the Moon away and, uh,
• 50:44
  the Earth's axis would still be fairly
• 50:46
  stable. It still wobbled between about 22 and
• 50:48
  24 degrees, maybe a little bit more. But
• 50:50
  quirkily, if you made the moon just 12
• 50:52
  kilometres larger in diameter,
• 50:55
  it would make the Earth's axis unstable and
• 50:57
  chaotic. So if the moon was only slightly
• 51:00
  larger, we would not be here. The
• 51:03
  other reason that a large moon has been
• 51:04
  suggested is that it drives bigger tides. And
• 51:07
  one of the common arguments for how life
• 51:09
  first got going and, um, for how life moved
• 51:12
  out of the oceans in both cases is to do with
• 51:14
  the large tidal intertidal areas that we
• 51:16
  have, where at low tide it's dry and at high
• 51:18
  tide it's underwater. And the idea is that
• 51:21
  without the moon those areas would be smaller
• 51:23
  and life would have had less chance to get
• 51:25
  going. I don't really buy that, because if
• 51:26
  you took the moon away, the tides of sun
• 51:29
  raises would still be half the size, so you'd
• 51:31
  still have substantial tides. But these are
• 51:33
  all the kind of questions people ask before
• 51:36
  you get to the planet itself. And the planet
• 51:38
  itself is where my head really hurt. Now, I'm
• 51:40
  not a geophysicist at
• 51:43
  all, so a lot of this was new to me. Now, we
• 51:45
  talked a little bit about the hydration. You
• 51:47
  could imagine anything from desert worlds to
• 51:49
  worlds with hundreds of kilometres depth of
• 51:51
  ocean. Now, if the ocean's too deep,
• 51:54
  the planet is probably habitable, but not
• 51:56
  detectably habitable because the life will be
• 51:59
  at the bottom of the ocean where the
• 52:00
  nutrients have been introduced by volc. But
• 52:02
  an ocean deeper than a few tens of kilometres
• 52:04
  is thought to become stagnant. And so it
• 52:07
  doesn't mix things up to the surface, so you
• 52:09
  don't want to look at water worlds that are
• 52:11
  ocean for hundreds or thousands of kilometres
• 52:13
  depth, but equally you want to have some mix
• 52:16
  of ocean and continent to allow all the
• 52:18
  carbon cycles and weathering to happen, to
• 52:20
  allow life to engage with the atmosphere. So
• 52:23
  that's a bit of a sweet spot there. But what
• 52:24
  I didn't realise was how critical
• 52:27
  water has been been to the
• 52:30
  maintenance of our atmosphere and um, thereby
• 52:33
  our climate against the vagaries of the solar
• 52:35
  wind and against the vagaries of plate
• 52:37
  tectonics. Now compare the Earth and Mars
• 52:40
  and the Earth is warm and wet. We've got a
• 52:42
  lovely thick atmosphere and we've not really
• 52:44
  lost much of our atmosphere. We've got the
• 52:46
  ozone layer which protects us to some degree
• 52:49
  from UV radiation. We've got a temperature
• 52:51
  inversion about 10 kilometres up in the
• 52:53
  atmosphere that traps water below that level.
• 52:55
  If water gets above that level, it freezes
• 52:57
  and falls back down. So the water can't get
• 52:59
  high enough to be ionised and split hydrogen
• 53:01
  and helium and lost. Mars doesn't have that.
• 53:05
  Mars doesn't have much of a magnetic field
• 53:06
  whereas the Earth does. And the magnetic
• 53:08
  field protects the atmosphere from being
• 53:10
  stripped away from the outside in. Mars
• 53:12
  doesn't have plate tectonics, but we do. And
• 53:15
  um, plate tectonics prevents the atmosphere
• 53:18
  from being precipitated out onto the surface
• 53:21
  through chemistry and trapped there because
• 53:23
  plate tectonics recycles the crust. So
• 53:25
  anything that chemically gets weathered onto
• 53:27
  Earth's surface gets put back into the
• 53:29
  atmosphere through volcanic volcanoes. So
• 53:32
  Mars and Earth probably started out looking
• 53:34
  very similar and are now very, very
• 53:36
  different. And so the nature of the planet
• 53:38
  itself is going to be a real important
• 53:40
  factor. And plate tectonics looks like it's
• 53:43
  going to be fairly key. Plate tectonics is a
• 53:46
  mechanism by which you stop the atmosphere
• 53:47
  getting precipitated out and frozen in onto
• 53:49
  the surface, which is a big part of what's
• 53:51
  happened m on Mars because of that recycling
• 53:53
  effect. But it also turns out that plate
• 53:56
  tectonics is key in ensuring the
• 53:58
  magnetic field is retained. And um, this is a
• 54:01
  bit that really hurt my head because I'm
• 54:03
  like, I'm not a geophysicist. Seems that on
• 54:06
  the Earth if the Earth didn't have plate
• 54:09
  tectonics, we'd probably have lost most of
• 54:11
  our magnetic field like Mars and like Venus.
• 54:15
  What's happening is that the magnetic field
• 54:16
  is driven by convection currents in the outer
• 54:19
  mantle. Like when you see water boiling in a
• 54:21
  kettle overturn, um, motion of mollie and
• 54:24
  metal Rising and falling. That
• 54:26
  convection can only happen if you've got a
• 54:28
  big temperature difference between the bottom
• 54:30
  and the top of the outer core. Sorry.
• 54:33
  In order to get that temperature difference,
• 54:35
  you need to be able to very effectively cool
• 54:37
  the top of the outer core because otherwise
• 54:39
  it would warm up so much convection would
• 54:40
  stop because you don't have enough
• 54:42
  temperature difference. The way the outer
• 54:44
  core is cooled is by convection in the
• 54:46
  mantle. That takes the heat away from the top
• 54:48
  of the outer core and brings it to the
• 54:49
  surface. We've got these huge convection
• 54:51
  cells in the mantle that transfer heat very
• 54:53
  quickly. Allowing cool the outer core's top
• 54:56
  to get this big temperature difference allows
• 54:59
  a motion that drives a magnetic field.
• 55:02
  That motion is also what drives plate
• 55:04
  tectonics. Now, the quirky thing that came
• 55:06
  out of all of this when I was reading about
• 55:07
  it is that, uh, if you run simulations of the
• 55:10
  motion of the Earth's mantle and the crust
• 55:12
  and the Earth is dry, the Earth is too small
• 55:15
  to sustain plate tectonics because the mantle
• 55:18
  is too stiff. If you have water
• 55:21
  and you mix water into the mantle, you
• 55:23
  lubricate, lubricate it. You allow convection
• 55:25
  in the mantle, which allows plate tectonics,
• 55:28
  which allows you to recycle the surface. But
• 55:31
  that plate tectonics also allows you to cool
• 55:33
  the outer core to maintain the magnetic
• 55:35
  field, allowing you to have that magnetic
• 55:37
  shield that protects your planet from the
• 55:39
  atmosphere being whittled away from the
• 55:40
  outside in by the solar wind. It
• 55:43
  seems that the storey of plate tectonics, the
• 55:46
  Earth's magnetic field and, um, the
• 55:48
  atmosphere being retained, is all tied
• 55:51
  together by water. Which brings us back to
• 55:53
  that delivery question. If the Earth had not
• 55:55
  got that veneer of water, would plate
• 55:57
  tectonics still happen? The infinite
• 56:00
  suggestion, and this was fabulous work by
• 56:02
  people working with the great Craig o',
• 56:03
  Neill, a great Australian scientist who does
• 56:06
  earthquakes and, um, plate tectonics
• 56:08
  modelling in an astrobiology sense that
• 56:11
  says the Earth's plate tectonics are
• 56:14
  really hard to get started. If you run models
• 56:15
  of the Earth without plate tectonics with the
• 56:17
  young Earth, with how hot it was, plate
• 56:19
  tectonics don't just happen. However, if
• 56:22
  you introduce impacts from big asteroids,
• 56:25
  like the things you got at the end of planet
• 56:27
  formation, those can dump enough energy
• 56:29
  in terms of a downward pulse to push magma
• 56:32
  up somewhere else to trigger a convection
• 56:35
  cell that then becomes self sustaining. So
• 56:38
  it's quite possible that the same impact
• 56:41
  regime that led to the delivery of water,
• 56:43
  that led in the extreme case to the formation
• 56:45
  of the moon, also triggered plate
• 56:48
  Tectonics. And by triggering plate tectonics
• 56:50
  and delivering water to the mantle allowed
• 56:53
  the Earth to become the planet it is today to
• 56:55
  allow life to thrive. Now there's far, far
• 56:58
  more that you could look into about the
• 56:59
  planets themselves. I'm not like, say, a
• 57:01
  geophysicist, but the interplay of these
• 57:04
  things is fascinating and it's a real
• 57:05
  reminder of that multidisciplinary thing. You
• 57:08
  can't do it all if you're just an astronomy.
• 57:10
  You need everybody from all different
• 57:13
  disciplines to come together so we can figure
• 57:15
  out what factors are and, um, aren't
• 57:17
  important. So that when we find another
• 57:20
  thousand, another ten thousand, another
• 57:22
  hundred thousand planets, we can pick the
• 57:24
  best targets to search for life upon them.
• 57:26
  And that was a motivation and it just blew my
• 57:28
  mind when I got to that final part. Just how
• 57:31
  much complexity there is in the
• 57:34
  interplay between the atmosphere, the
• 57:35
  climate, the plate tectonics, the oceans
• 57:38
  that are so, uh, variable and so chaotic.
• 57:42
  What does that mean? How can we learn from
• 57:44
  that? Well, that's what we learn when we look
• 57:46
  at planets around other stars. But at least
• 57:47
  this gives us a bit of a starting point
• 57:49
  point, I think.
• 57:50
  Andrew Dunkley: Yeah, yeah, I see what you're saying. So it's
• 57:53
  like the popular press saying, oh, we found a
• 57:55
  rocky planet in the Goldilocks zone and it
• 57:57
  probably has water, so, you know, it's got to
• 57:59
  have life. Uh, there's so much more than
• 58:02
  that. Like, yeah, it's um.
• 58:04
  Jonti Horner: Even they probably have water is a leap
• 58:06
  because like, yeah, if we'd not had
• 58:09
  water added after the moon forming impact,
• 58:11
  the Earth would be a desert
• 58:14
  Andrew Dunkley: and we wouldn't probably exist at all.
• 58:17
  Jonti Horner: Absolutely, yeah.
• 58:18
  Andrew Dunkley: Fascinating stuff, Jonty. We'll leave it
• 58:21
  there. But, um, it's just such a
• 58:24
  fascinating topic. But
• 58:26
  what goes into, uh, the future
• 58:29
  identification of potential targets is
• 58:32
  so much more than most people would have
• 58:34
  considered. So thank you very much, really
• 58:35
  appreciate it.
• 58:36
  Jonti Horner: It's an absolute pleasure and thanks for
• 58:37
  letting me rant on my topics of choice for a
• 58:40
  change. Like I said, it would be helpful. I'm
• 58:43
  sure your readers will.
• 58:44
  Readers, listeners will give feedback on
• 58:46
  this, but I know we've done something
• 58:48
  different. I really do. I am aware
• 58:51
  of the fact that these are not your typical
• 58:52
  episodes and that may be different for
• 58:55
  people. So I appreciate the opportunity to do
• 58:56
  this, but if people have enjoyed it or
• 58:58
  didn't, it'd probably be worth letting Andrew
• 59:00
  and Fred Watson know once I'm gone. Um, won't
• 59:03
  hurt my feelings. Don't worry about it
• 59:04
  because if it's Something you've enjoyed.
• 59:06
  There's possibilities to do things like this
• 59:08
  again in future if it isn't. We tried it and
• 59:10
  it didn't work and that's entirely fine. Fine
• 59:12
  too. So hopefully it was fun, hopefully it
• 59:14
  was educational and I won't be too hurt, uh,
• 59:16
  if nobody enjoyed it.
• 59:18
  Andrew Dunkley: I'm pretty sure they did. Jonty, and we
• 59:20
  really appreciate your time and uh, we've,
• 59:23
  we've got one more episode to do with you.
• 59:25
  Uh, it's a Q and A episode and we, we're
• 59:27
  talking about, we haven't nailed it down yet,
• 59:29
  but we're talking about doing a, an
• 59:31
  astrophotography special.
• 59:32
  Jonti Horner: Yeah.
• 59:33
  Andrew Dunkley: Because we do get a lot of questions about
• 59:34
  astrophotography so, uh, that, that'd be
• 59:37
  worth getting into as well.
• 59:38
  Jonti Horner: Yeah. I've got a couple of good friends who
• 59:40
  uh, are award winning astrophotographers who
• 59:42
  we're going to try and rope into that. So
• 59:44
  watch this space is what I'd say. Yes.
• 59:46
  Andrew Dunkley: Fingers crossed we can nail that one down.
• 59:49
  Jonty, thanks so much. We'll see you real
• 59:50
  soon.
• 59:51
  Jonti Horner: Pleasure. Thank you for having me.
• 59:52
  Andrew Dunkley: Johnty Horner, professor of Astrophysics at
• 59:54
  the University of Southern Queensland.
• 59:58
  And if you've got time, jump on our website
• 1:00:00
  and have a look around. Uh, maybe send your
• 1:00:02
  comments and thoughts, uh, to us via the
• 1:00:05
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• 1:00:07
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  more. So cheque it out and thanks to Huw
• 1:00:25
  in the studio as always, because
• 1:00:28
  he does something which we one day might
• 1:00:31
  find out about. And from me, Andrew Dunkley,
• 1:00:33
  thanks for your company. We'll see you on the
• 1:00:35
  next episode of Space Nuts. Bye Bye.
• 1:00:38
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