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Meteor Showers, Mars Missions & the Mystery of Stranded Astronauts · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Andrew Dunkley: Hi there. Thanks for joining us. This is
• 0:01
  Space Nuts, where we talk astronomy and space
• 0:04
  science, uh, every week, uh, on
• 0:06
  various topics. And the topics of the day,
• 0:09
  uh, this week include meteor showers.
• 0:12
  Uh, there's one happening as we speak and
• 0:15
  another one coming up which, uh, we'll be
• 0:17
  talking about. Uh, the Mars
• 0:19
  Escapade mission is, um,
• 0:22
  on its way. Uh, we talked about that, I think
• 0:25
  a week or two ago, wondering, uh, because
• 0:27
  they were running into a bit of trouble. But,
• 0:29
  um, I think they're all systems
• 0:32
  go now. Uh, but this is, uh, not
• 0:35
  all systems go. This is involving Chinese
• 0:38
  astronauts, uh, that are stranded on their
• 0:41
  space station. And we're going to chase some
• 0:43
  stars using a process called
• 0:45
  gyrochronology. That's all coming up
• 0:48
  in this episode of space nuts.
• 0:50
  Voice Over Guy: 15 seconds. Guidance is internal.
• 0:53
  10, 9. Ignition
• 0:56
  sequence start. Space nuts. 5, 4,
• 0:59
  3, 2. 1, 2, 3, 4, 5.
• 1:03
  Space nuts. Astronauts report it feels good.
• 1:07
  Andrew Dunkley: And joining us again to go through all of
• 1:09
  that is Professor Jonti Horner, professor of
• 1:12
  Astrophysics at the University of Southern
• 1:14
  Queensland. Hi, Jonti.
• 1:16
  Jonti Horner: Good morning. How are you going?
• 1:17
  Andrew Dunkley: I am well. Good to see you. Love your T
• 1:19
  shirt.
• 1:21
  Jonti Horner: Fc. Yeah. So much for the outreach.
• 1:24
  T shirts today. I was groggy when I woke up
• 1:26
  and football talks just feel so comfortable.
• 1:28
  Andrew Dunkley: Yeah, they do, don't they?
• 1:30
  Jonti Horner: Yeah. You pay a lot of money for them, I've
• 1:31
  got to say that. But they last forever. I've
• 1:33
  still got some from kind of more than 20
• 1:35
  years ago that are wearable, which can't say
• 1:38
  for most of the clothes I buy.
• 1:39
  Andrew Dunkley: Well, my, uh, I've got three football
• 1:42
  shirts and they're all wonderful. Cincinnati
• 1:44
  Bengals, the Manly, uh, Waringa Sea
• 1:47
  Eagles, and the New South Wales Blues,
• 1:49
  although I don't get to wear that one very
• 1:50
  much. Uh, and, uh, I've got
• 1:53
  four golf shirts that I wear just
• 1:56
  when I'm playing. And they're. They're all
• 1:57
  the most comfortable shirts I've got.
• 1:59
  Jonti Horner: So.
• 2:00
  Andrew Dunkley: I agree.
• 2:02
  Jonti Horner: Does remind me of the Sam Vines,
• 2:05
  um, Law of Boots, which became a rallying
• 2:08
  cry in the UK about the cost of living thing.
• 2:10
  So this is another Terry Pratchett thing.
• 2:12
  Although I think it's like most things Terry
• 2:14
  Pratchett did, he was drawing on the wisdom
• 2:15
  of people who came before as well as being
• 2:17
  very wise himself, but talking about the,
• 2:19
  the, um, impacts of poverty and the fact that
• 2:22
  he could never get his boots to last more
• 2:24
  than, you know, one season, wandering around,
• 2:26
  being a copper, walking around on the cobble
• 2:28
  streets of an park. And he paid $10 for a
• 2:31
  pair of boots every time. Um, but the tough.
• 2:33
  The wealthy would pay $50 for a pair of boots
• 2:35
  that would last a lifetime. And so very
• 2:38
  quickly he became poorer because he was
• 2:40
  continually having to buy cheap boots and
• 2:42
  spending more money on the boots. And this
• 2:44
  actually became part of a big campaign in
• 2:47
  the UK for reducing the cost of food and
• 2:50
  looking after people who were in poverty, led
• 2:52
  by a really interesting person called Jack
• 2:54
  Monroe, who's a bootstrap cook, who is
• 2:57
  someone who's been in quite severe poverty
• 2:59
  and has had a number of cookbooks about how
• 3:01
  to eat well at an incredibly low, uh,
• 3:04
  price, you know, from the bargain bin at the
• 3:05
  supermarkets and stuff like that. And I think
• 3:07
  for a while that campaign had a really kind
• 3:10
  of strong backing and made a certain
• 3:13
  amount of social change all off the back of
• 3:15
  the idea that the cheaper something is, the
• 3:17
  less time it lasts, so the more you'll end up
• 3:19
  spending in the long term. Yes, great
• 3:22
  example. You get what you pay for.
• 3:23
  Andrew Dunkley: Well, yeah, absolutely true. Um, my wife
• 3:26
  spends a lot of time researching ways of
• 3:29
  reducing our grocery bill. And she,
• 3:32
  she found a woman in the United States who
• 3:34
  does it for a super cheap,
• 3:38
  um, monthly figure, uh, and she
• 3:40
  translated that into Australian dollars and
• 3:42
  went, I'm going to try this. And I think
• 3:45
  we're up to months 23, and
• 3:47
  we, we're doing really well. And it's, it's
• 3:50
  knocked hundreds of dollars off our monthly
• 3:53
  spend. It's quite remarkable that we can do
• 3:55
  it the way we've, we've done it. And, um,
• 3:58
  yeah, m. I'm, I'm very happy with the
• 4:01
  results. The food's great and, uh, we're
• 4:03
  doing it uber cheap.
• 4:05
  Jonti Horner: Well, it's always fighting. I think there's a
• 4:07
  real conflict with the kind of cost of living
• 4:10
  crisis, but also the fact that people are
• 4:11
  working harder and longer than ever these
• 4:13
  days. True. Because one of the ways to reduce
• 4:16
  your spend on food is to cook everything from
• 4:17
  scra. You get the veggies and the meat and
• 4:20
  the spices and make every meal yourself from
• 4:22
  scratch. But the, you get the less time
• 4:24
  you've got for that, so the more tempting,
• 4:26
  the kind of prepackaged, less healthy, more
• 4:28
  expensive options, uh, are. Because you've
• 4:31
  got that sunk cost, not sunk cost fallacy,
• 4:33
  but you've got that cost of the time that is
• 4:35
  available to you, which, yes. On the money
• 4:38
  you have to spend. It's all really bizarre
• 4:40
  and intertwined and all this stuff that I
• 4:42
  didn't realize as a teenager when I was so
• 4:43
  keen to be grown up well, like.
• 4:46
  Andrew Dunkley: When we were kids, you bought food and it
• 4:48
  costs what it costs to put on the shelf plus
• 4:51
  the profit margin. Um, but
• 4:54
  now they build in all these loyalty programs
• 4:57
  and points programs and all these other
• 4:59
  things that increase the price and
• 5:03
  it's all hidden. And if you're not
• 5:07
  one of those customers that joins the loyalty
• 5:09
  program, you're actually
• 5:13
  bankrolling everybody else who's a part of it
• 5:15
  because you're still paying the extra.
• 5:16
  Jonti Horner: It's, I mean that's all an interesting one
• 5:19
  online and we are totally off topic. Yeah, we
• 5:21
  are. But discussion online the other day
• 5:23
  about the fact that a certain brand of soft
• 5:25
  drink over here in Australia is cheaper to
• 5:28
  buy in 1.25 liter bottles and 600 mil
• 5:31
  bottles, yet everybody will grab the 600 mil
• 5:33
  bottle because of the convenience and all the
• 5:35
  rest of it. Um, and they typically have the
• 5:38
  1.25 liter bottles somewhere else in the
• 5:40
  store and all this stuff. Yeah, yeah. It's
• 5:43
  just bizarre how willing we are
• 5:46
  to just, I don't know, buy into that kind of
• 5:48
  thing and not even think about it. Because
• 5:49
  convenience has a cost.
• 5:51
  Andrew Dunkley: Yes. But when they put a 30 pack of
• 5:54
  um, of whatever on the shelf in a, in a
• 5:57
  big carton at 50 bucks, there's
• 6:00
  no, there's no way, no way I'm
• 6:03
  spending 50 bucks on a carton of Coke or
• 6:05
  whatever. Yeah, that's, that's outrageous.
• 6:08
  Okay, we better get on with it.
• 6:09
  Um, now, uh, something is uh, making the
• 6:12
  news at the moment. It's the Leonid meteor
• 6:15
  shower, uh, which uh, has kind of
• 6:18
  reached its peak now. So by the time some
• 6:20
  people hear this, it may be long past. But
• 6:23
  uh, it's a really good one because it's had
• 6:25
  some, some big highs in years
• 6:28
  past, maybe not so much this year. But
• 6:30
  uh, it, it's sort of one of the big ones,
• 6:32
  isn't is, I.
• 6:34
  Jonti Horner: Mean it's another example. I always, whenever
• 6:36
  there's a meteor shower making the news and
• 6:38
  it seems to happen more and more often thanks
• 6:39
  to the um, click
• 6:42
  starved industry in the Northern hemisphere,
• 6:44
  wanting every click there come from people on
• 6:46
  social media. Um, every meteor shower that
• 6:49
  comes along gets a lot of stories written
• 6:51
  about this is the best one of the year and
• 6:52
  you need to go out and see it and the sky
• 6:54
  will fall and I get grumpy. Um,
• 6:57
  the Leonids are not the best meteor shower of
• 6:59
  the year except when they are and the year is
• 7:01
  the years when they're not. What I mean by
• 7:03
  this is that many ah, of the meteor showers
• 7:06
  we see that are the really reliable annual
• 7:08
  ones are uh, meteor showers where
• 7:11
  we are not passing exactly where the comet
• 7:13
  has passed. We're passing through a tube of
• 7:15
  debris that has spread out from the comet's
• 7:17
  orbit over very long periods of time.
• 7:20
  And so in a typical year the material we go
• 7:22
  through has about the same density as the
• 7:24
  last year, so we get about the same number of
• 7:26
  meteors. So you can imagine for example the
• 7:28
  Orionids and the Yteraquarids which are born
• 7:31
  of Comet Hallie, or you can imagine the
• 7:32
  Perseids born of Comet Swift Tuttle, where
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  you've got these Hallie type comets that have
• 7:37
  been trapped on their current orbits or
• 7:38
  thereabouts for thousands of years. Every
• 7:41
  time they go around the sun they lay down
• 7:42
  trails of dust that currently wouldn't
• 7:45
  intersect the Earth because the comets orbits
• 7:47
  come close to the Earth but they don't
• 7:49
  exactly cross us. But over time that dust has
• 7:51
  spread out and you've got these tubes that
• 7:53
  are tens of millions of kilometers, even 100
• 7:55
  million kilometers across in three
• 7:58
  dimensions. So we run through the tube, but
• 8:00
  not where the comet currently is. And so
• 8:02
  we're getting the dust after it's spread out
• 8:04
  for a good long period of time. With the
• 8:06
  perses, you occasionally get enhancements
• 8:08
  when the comet's relatively nearby because
• 8:10
  the dust is a bit denser. And that's because
• 8:13
  comets with Tuttle's ah, orbit comes a bit
• 8:15
  closer to perfectly intersecting the Earth's
• 8:17
  orbit than Comet Halley's does. And so we do
• 8:20
  get a bit more variability there. With
• 8:23
  the Leonids we've got a slightly different
• 8:25
  situation. The meteor stream itself is
• 8:28
  younger, which I would argue suggests that
• 8:30
  the parent comet, 55P Temple Tuttle,
• 8:33
  hasn't been trapped on its current orbit for
• 8:35
  as long, so it hasn't had time to lay down as
• 8:37
  much debris. It's also a smaller comet, so
• 8:39
  it's laying down a bit less material every
• 8:41
  time it goes around the sun. But the Earth's
• 8:44
  running into the debris from that comet
• 8:46
  pretty much head on. Which means that the
• 8:48
  particles from Comet Temple Turtle hit the
• 8:50
  Earth's atmosphere at about the maximum speed
• 8:52
  anything can and still be bound to the solar
• 8:54
  system. So these meteoroids hit at 71,
• 8:57
  72 km a second and that means they're
• 8:59
  typically a bit brighter for a given size
• 9:01
  than other meteor showers. So in other words,
• 9:04
  we can see the smaller bits of dust and that
• 9:06
  helps give a bit of a boost to the rate that
• 9:09
  you'd see. But typically in an average year
• 9:12
  the Leonids would give you between 10 and 15
• 9:14
  meters per hour as a zenithal
• 9:17
  hourly rate. And the zenithal hourly rate is
• 9:20
  this magic number that astronomers use to
• 9:23
  quantify how strong a meteor shower is to
• 9:25
  compare it with other meteor showers. It is
• 9:27
  the theoretical maximum number of meteors you
• 9:30
  would see if you have perfect eyesight,
• 9:33
  if you have perfectly dark skies and
• 9:35
  perfectly clear skies. And the radiant of the
• 9:37
  meteor shower, the point from which all the
• 9:39
  meteors appear to diverge was directly
• 9:41
  overhead. So in reality, whenever you see a
• 9:43
  ZHR listed for a meteor shower, you probably
• 9:46
  will see fewer meteors than that in an hour.
• 9:48
  Except for the fact that meteors are like
• 9:50
  buses. You'll wait five minutes and three
• 9:52
  will come along at once. And so with that bit
• 9:54
  of noise, you may occasionally get an hour
• 9:56
  where you get a bit higher rate and then the
• 9:57
  next hour will be a bit lower. So typical
• 10:00
  year leonids give you 10 to 15 an hour.
• 10:03
  But the Earth intersects very well with
• 10:05
  the orbit of comet Temple Tuttle, which means
• 10:08
  that in theory there's a very small chance at
• 10:10
  some point in the future the thing could hit
• 10:12
  us, but it probably won't. Almost certainly,
• 10:14
  uh, it won't. A bit like Swift Tuttle's a
• 10:16
  similar situation actually, but Comet Temple
• 10:18
  Tuttle's more pronounced. What
• 10:21
  that means is that the debris that has been
• 10:24
  laid down by comic Temple Tuttle in very
• 10:26
  recent times at previous orbits can actually
• 10:29
  interact and hit the Earth, uh, if we're
• 10:31
  lucky, on the first lap after it was dropped
• 10:34
  or the second lap after it was dropped. And
• 10:36
  what happens with the dust released from a
• 10:38
  comet is that, uh, it spreads out ahead and
• 10:41
  behind the comet in its orbit relatively
• 10:43
  quickly. So if you eject a dust grain from
• 10:45
  the comet in the forwards direction when the
• 10:48
  comet's near perihelion, that dust grain will
• 10:50
  be going quicker than the comet, so will
• 10:52
  therefore move on a longer period orbit. And
• 10:54
  by the time the comet comes back, that dust
• 10:56
  will be behind the comet and it will arrive
• 10:58
  after the comet. And similarly, any dust
• 11:00
  that's ejected backwards will, will be moving
• 11:02
  slower than the comet, it will have a shorter
• 11:04
  orbit than the comet and it will come back
• 11:06
  before the comet. So what this means is that
• 11:08
  you effectively get almost like these spears
• 11:10
  or javelin shaped streams of
• 11:13
  dust where there is a lot more dust,
• 11:16
  which is the dust that was laid down in the
• 11:17
  previous orbit. And these spikes will be
• 11:20
  millions of kilometers long, but relatively
• 11:22
  narrow in space initially. It takes them
• 11:25
  a long time to spread out. And um, that's the
• 11:27
  dust that's been pumped into the wider stream
• 11:29
  that when it diffuses and spreads out will
• 11:31
  form the wider meteor stream. Now because
• 11:33
  these spikes are really, really narrow in
• 11:36
  space, we either hit them or we miss them.
• 11:38
  And if we miss them, there's nothing to write
• 11:40
  home about. But if we run through one of
• 11:42
  these spikes, we'll get enhanced
• 11:44
  meteor numbers. And the more material in the
• 11:47
  spike, the higher the rates we'll get. And
• 11:49
  that's why the Leonids are the source of some
• 11:51
  of the most famous and most spectacular
• 11:53
  meteor storms of all time. We're talking
• 11:55
  about years like 1799,
• 11:57
  1833, Hades of really famous one
• 12:00
  because that was a storm that was visible
• 12:02
  over the Americas with more than 100,000
• 12:04
  meteors per hour, where light in the sky
• 12:07
  was bright enough to wake miners who were
• 12:09
  camped outside, their minds in tents. And it
• 12:11
  had the uh, more religious side of people in
• 12:14
  the US convinced that the apocalypse had
• 12:16
  come, that the end times had arrived. Yeah,
• 12:18
  ah, the judgment day had come. You know,
• 12:20
  people were terrified. So that was utterly
• 12:23
  fascinating. But at the same time that was
• 12:25
  very much kind of the birth of modern meteor
• 12:27
  science because people studied it, figured
• 12:29
  out what was going on. The
• 12:32
  Leonids have a really important part in our
• 12:34
  meteor history. There were big storms in 1965
• 12:37
  and 1966. After about a century
• 12:39
  of nothing, there was big storm in 1866,
• 12:43
  then the next two 33 year periods, the
• 12:45
  comets orbital periods, about 33 years pass
• 12:48
  with a whimper rather than a bang.
• 12:51
  1965, nobody really expected anything, but
• 12:54
  there was a big outburst of bright meteors.
• 12:56
  And then in 1966 there was a big storm.
• 12:59
  So by the time the late 90s came along,
• 13:02
  we had this huge industry of researchers
• 13:05
  studying the lean in meteor shower, trying to
• 13:08
  predict what would happen in
• 13:09
  1999-2000-2001-2002,
• 13:13
  and developing this kind of modeling theory
• 13:16
  based on those javelins of dust, effectively
• 13:18
  based on modeling the dust after it was
• 13:19
  ejected to predict when we'll cross
• 13:22
  trails. And they did a fairly good job of
• 13:24
  predicting the strength of and um, the time
• 13:26
  of the big outbursts, the last one of which
• 13:28
  was in 2002 where there were a few thousand
• 13:30
  meteors per hour. Since then, rates have
• 13:33
  gone back to normal, um, occasionally.
• 13:36
  Now we have the potential of crossing
• 13:39
  streams. Now the comet doesn't pass
• 13:41
  perihelion for another eight years, so we're
• 13:43
  still far away from that. So we wouldn't
• 13:45
  expect a big outburst in the next year or
• 13:47
  two. But we're starting to get to the point
• 13:49
  where we might clip the ends of these spares
• 13:51
  in space. And start seeing enhanced threats.
• 13:53
  Now the bad news for everybody is that, uh,
• 13:55
  Jupiter and Saturn are conspiring to nudge
• 13:57
  the orbit of the comet around. And we
• 13:59
  probably won't get another great lean in
• 14:01
  storm until 2099. But we will
• 14:04
  see some enhancement in rates through the
• 14:05
  early 2000s and again in the early to
• 14:08
  mid-2060s. Um, from the stream.
• 14:11
  All that comes back to this year's shower.
• 14:13
  This year's shower was forecast to be fairly
• 14:15
  average, but we did have three or four
• 14:18
  potential very old stream crossings. Forecast
• 14:20
  one back on the 9th of November, and I've not
• 14:22
  seen anything about that that would be very
• 14:24
  weak because that was dust laid down in
• 14:26
  1167. Wow. A small
• 14:28
  outburst on the 15th, which I've seen no
• 14:31
  reports of, that was a 1633 dust stream.
• 14:34
  But then a couple of hours after the forecast
• 14:36
  peak, which is tonight, Australia time, as
• 14:39
  we're recording at early hours of Tuesday
• 14:41
  morning, um, there is both a
• 14:43
  regular maximum but also a potential crossing
• 14:46
  of a couple of dust streams from 1699.
• 14:50
  Now none of these will really boost the rates
• 14:52
  above that 10 or 15 per hour, but there are
• 14:54
  really important tests for our models
• 14:57
  of how well we can predict where these dust
• 14:59
  streams will be and how dense they'll be. And
• 15:02
  it's not the most straightforward process.
• 15:04
  People who are doing this research have to
• 15:07
  track the comet's orbit back in time, which
• 15:08
  is where ancient comet observations are
• 15:10
  really useful, old observations of the comet.
• 15:12
  To pinpoint it, they need to then have a
• 15:15
  model of how the dust grains are ejected from
• 15:17
  the comet at each perihelion, how the non
• 15:20
  gravitational forces like radiation pressure,
• 15:22
  the Ponting Robertson effect, all these
• 15:24
  effects push the dust grains around and they
• 15:26
  have to then run them forward in time with
• 15:28
  the gravity of all the planets and all those
• 15:30
  non gravitational forces to figure out where
• 15:32
  they cluster near the Earth's orbit. So it's
• 15:35
  very complex modeling and anything we can do
• 15:36
  to ground truth that by getting observations
• 15:38
  of the meteor shower are really useful. So if
• 15:41
  we see an uptick and we see the rates are a
• 15:42
  bit higher or a bit lower than predicted,
• 15:45
  that allows us to refine the models so that
• 15:47
  when it comes to the bigger potential
• 15:50
  numbers, which next year could be a slightly
• 15:52
  better year, potentially up to 30 or 40 an
• 15:54
  hour depending on some of the models, for
• 15:55
  example, we can have more confidence in that.
• 15:58
  So that's really what's going on with the
• 15:59
  Lenith. So while I get grumpy about the
• 16:02
  stories, encouraging people who are not fans
• 16:04
  of astronomy normally to go out and spend
• 16:06
  their nights out in the Northern Hemisphere,
• 16:07
  cold in the Southern Hemisphere, heat and
• 16:10
  humidity and rain that we're getting at the
• 16:11
  minute. I get a bit grumpy because this isn't
• 16:14
  the shower to watch for that. If you're not a
• 16:16
  mad keen meteor fan anyway, this isn't
• 16:19
  the one to watch. What you should do is wait
• 16:21
  a month and look at the Geminis, which we can
• 16:23
  talk about in just a little minute.
• 16:25
  Andrew Dunkley: Yes. Uh, and we might as well just jump
• 16:28
  straight into that because, uh, they're due
• 16:30
  mid December.
• 16:32
  Jonti Horner: Yes.
• 16:33
  So, you know, I always love meteor showers.
• 16:36
  Meteor showers are part of what hooked me in
• 16:38
  and kept me in as a kid. So I've always got a
• 16:40
  soft spot in my heart for them. And back in
• 16:43
  the 90s, we had. The
• 16:45
  Perseids were clearly the strongest meteor
• 16:48
  shower of the year from the Northern
• 16:49
  Hemisphere. And that's a shower that's active
• 16:51
  in August. And the caveat is we don't really
• 16:53
  see that very well in the Southern
• 16:55
  Hemisphere. Yeah. We then have the
• 16:57
  Quadrantids at the start of January, which
• 17:00
  are, uh, one of the year's best three
• 17:01
  showers, but a very hit and miss. They're
• 17:03
  only at their peak for a very short period of
• 17:05
  time, just a few hours. And, um, they are
• 17:07
  again very much a Northern Hemisphere only
• 17:09
  shower. Then we have the Geminids. And the
• 17:11
  Geminids were first seen, I think, in the
• 17:13
  late 1800s, and
• 17:16
  ever since they've been getting stronger. So
• 17:19
  they started off as one of the year's
• 17:20
  moderate showers and they've grown in
• 17:22
  strength. And by the early 1990s when I was
• 17:25
  watching them, they had a zenithal hourly
• 17:26
  rate, the ZHR, of about 100 per hour.
• 17:29
  That's now up to 150 an hour. And they are
• 17:32
  undisputedly the king of the meteor showers
• 17:35
  in a typical year, unless we get like a
• 17:37
  meteor storm from one of the episodic showers
• 17:39
  like the Leonids or the Jacobeenids or the,
• 17:42
  or something like this in a normal year.
• 17:45
  The Geminids of the King, and they're very,
• 17:47
  very reliable. They're also,
• 17:50
  um, the only one of those big three meteor
• 17:52
  showers that is easily seen from the Southern
• 17:54
  Hemisphere. The Northern Hemisphere still
• 17:56
  gets the best views, undeniably because the
• 17:58
  radiant for the Geminids is north of the
• 18:00
  equator. So easier to get high in the sky
• 18:03
  from northern latitudes, rises earlier,
• 18:06
  stays up longer, all the rest of it. But
• 18:09
  even from Australia and other Southern
• 18:11
  Hemisphere locations, the Geminids are really
• 18:13
  good. They're at the peak on the nights of
• 18:16
  the 13th and the 14th of
• 18:18
  December, the night of the 13th into the
• 18:21
  morning of the 14th is the best for most
• 18:23
  people. For us here in Australia because
• 18:25
  we're so far ahead on the clocks the rates
• 18:27
  will be building to their peak before dawn on
• 18:30
  the morning of the 14th, that's night of the
• 18:32
  13th and then falling away from the peak very
• 18:35
  slowly on the evening of the 14th. The peaks
• 18:37
  during our daylight hours but the Gemnids
• 18:40
  have quite a broad peak as well so they're
• 18:42
  worth watching for a couple of days either
• 18:44
  side of maximum. Um, well worth going out,
• 18:47
  camping, getting away from street lights,
• 18:49
  getting to a dark site. If you're at uh, my
• 18:52
  latitude in Southeast Queensland you'll see
• 18:54
  the first gemnids from about 9, 30, 10 o'
• 18:56
  clock at night. But the best rates are later
• 18:58
  in the evening. The peak rates anywhere on
• 19:00
  the planet are about 2am or
• 19:03
  3am if you've got daylight savings like the
• 19:05
  people in the southern states of Australia,
• 19:07
  you move your clocks forward an hour, you
• 19:08
  move everything forward an hour. But the
• 19:11
  further north you are on the planet the
• 19:13
  earlier you can start watching. And for me
• 19:15
  growing up in the UK the radiant was above
• 19:17
  the horizon pretty much after sunset and was
• 19:20
  above the horizon all night. So even as a 12
• 19:22
  year old when my parents were grumbling that
• 19:24
  I should do my homework and I needed an early
• 19:26
  night school the next morning I could still
• 19:28
  get a decent show before I went to sleep.
• 19:31
  Nowadays if I was still in the northern
• 19:32
  hemisphere I'd be able to stay up all night
• 19:34
  because I'm a grown up and I can pick what I
• 19:36
  do but it will be cold and miserable so I
• 19:38
  might not do that. But it is a global
• 19:40
  opportunity to see a really good meteor
• 19:42
  shower and they are the best one of the uh
• 19:43
  year. So yeah, book your camping, book your
• 19:45
  holidays, find a dark site and don't blame me
• 19:48
  for the weather.
• 19:49
  Andrew Dunkley: Yes, yes, you can never do much about that.
• 19:51
  You just got to keep your fingers crossed.
• 19:53
  But uh, yeah a um, couple of meteor
• 19:56
  showers to keep an eye out for the Leonids
• 19:58
  happening as we speak Ish and the
• 20:00
  Geminids in mid December. Uh, you can look
• 20:03
  up the times and dates and
• 20:06
  etc uh online. This is
• 20:09
  Space Nuts with Andrew Dunkley and Jonti
• 20:12
  Horner.
• 20:15
  Jonti Horner: Roger, you're allowed to start here also
• 20:16
  Space Nuts.
• 20:18
  Andrew Dunkley: Now this, this uh, is a great story. Uh the
• 20:20
  Mars Escapade mission has
• 20:23
  lifted off successfully and this uh, is a
• 20:26
  good story for a number of reasons.
• 20:27
  Jonti Horner: In fact Jonti, it is. This is one where I
• 20:30
  feel like I'm going to be jumping off in
• 20:31
  several directions all at once. So it's
• 20:32
  almost like three mini segments in a way.
• 20:34
  Andrew Dunkley: Yeah.
• 20:36
  Jonti Horner: We spoke last week about the US shutdown and
• 20:39
  um, the issues it was causing for airspace
• 20:41
  over the US and um, the resulting ban on any
• 20:44
  rocket launchers other than between 10pm and
• 20:47
  6am and of course, fairly quickly after we
• 20:49
  talked about it, the shutdown was finally
• 20:52
  sorted and agreed and fixed. My
• 20:55
  understanding is that now everybody's trying
• 20:56
  to get the wheels turning on the bus again,
• 20:58
  so trying to get everything back into action.
• 21:01
  But that air traffic control
• 21:03
  restriction was still in space because it
• 21:06
  takes time to ramp things back up. This was
• 21:08
  relevant for spaceflight, particularly
• 21:10
  because of this NASA mission. Now, NASA has
• 21:13
  been shut down since the 1st of October, but
• 21:16
  fortunately this mission was already out of
• 21:18
  their hands in the hands of the launch
• 21:20
  provider. So the shutdown wasn't going to
• 21:22
  stop it, but where it could delay it was that
• 21:24
  the rocket needed to launch in daylight hours
• 21:27
  to be point for the Earth to be pointing in
• 21:28
  the right direction. Yeah. And so
• 21:31
  with the shutdown happening, um, they were on
• 21:34
  dodgy ground. They were hoping to launch just
• 21:36
  before the shutdown came in, but that launch
• 21:37
  got scrubbed. Then they got a waiver to
• 21:40
  launch during daylight hours because of
• 21:42
  special exemption from Florida. And that
• 21:44
  launch got scrubbed. But it finally managed
• 21:46
  to launch on Friday. This
• 21:49
  was launched by the commercial provider Blue
• 21:51
  Origin, whose new Glenn rocket put the thing
• 21:54
  up into space. And, um, it was a
• 21:56
  noteworthy launch for Blue Origin here
• 21:59
  because, hey, look, they've launched
• 22:00
  something that is going beyond the Earth Moon
• 22:03
  system. That's going to Mars. I mean, that's
• 22:04
  really cool. Anyway. But also their new Glenn
• 22:07
  rocket, the first stage, the lower stage, a
• 22:10
  big chunky thing that does a lot of the work
• 22:11
  to get you most of the way out of the
• 22:13
  atmosphere. Once that had detached from the
• 22:16
  second stage, it plummeted back down towards
• 22:18
  the Earth. And a couple of minutes after that
• 22:21
  stage separation, it turned its engines back
• 22:23
  on, stood up on its tail and landed safely
• 22:26
  on a barge in the ocean called Jaclyb.
• 22:29
  Now, we're kind of used to SpaceX managing
• 22:31
  this. They've been doing this for a while.
• 22:33
  But that ability to land and, um, recover
• 22:36
  your boosters to reuse them is actually
• 22:39
  really, really important. It's one of these
• 22:41
  things that allows you to reuse your boosters
• 22:45
  and so therefore by reusing them, you
• 22:48
  reduce the cost of future launches, which is
• 22:51
  part of what makes commercial spaceflight
• 22:52
  feasible. And, um, this is only the second
• 22:55
  company ever to manage this kind of Soft
• 22:57
  landing, safe landing type process
• 23:00
  M. So it's really remarkable that they
• 23:02
  actually achieved it. There's some fabulous
• 23:04
  videos out there. People are really thrilled
• 23:06
  watching these things happen. And it's a
• 23:08
  fabulous technological achievement. So it's a
• 23:10
  plus one and a tick for Blue Origin. They're
• 23:12
  very pleased with their role on this
• 23:15
  escapade itself is really interesting.
• 23:17
  It's launching out of sequence. Normally we
• 23:19
  get launchers to Mars in a big batch every 26
• 23:22
  months or so. And the reason for that is
• 23:25
  that Mars and the Earth move, uh,
• 23:27
  around the sun, um, with periods that are
• 23:29
  similar enough that Mars is closest to the
• 23:32
  Earth every 26 months or so.
• 23:35
  Now, if you want to get the cheapest,
• 23:36
  quickest flight to Mars, you don't launch
• 23:39
  when the Earth's on the opposite side of the
• 23:40
  sun to Mars because that means you've got to
• 23:42
  go the long way around. So people tend to
• 23:44
  wait for the launch window when they can do
• 23:45
  the shortest, quickest trip. And Instead of
• 23:48
  taking 12 or 18 months to get there, they can
• 23:51
  get there within six months and it's all nice
• 23:52
  and easy and cruisy. And the next launch
• 23:55
  window doesn't actually open until about this
• 23:57
  next time next year.
• 23:59
  Escapade, though, has an interesting launch
• 24:01
  window in that it's not launching directly to
• 24:03
  Mars, it's doing something different. It's
• 24:06
  going to launch out to the second Lagrange
• 24:08
  point, the Sun, Earth. Lagrange point number
• 24:10
  two, which is beyond the Earth and its orbit
• 24:12
  between the orbits of Earth and Mars, about a
• 24:14
  million kilometers further from the sun than
• 24:16
  we are. And the Tiffany is where a few space
• 24:18
  observatories like the James Webb Space
• 24:20
  Telescope are hanging out, spending their
• 24:22
  time. Escapade is going to hang
• 24:25
  around there for about 12 months then, then
• 24:27
  this time next year, as the launch window to
• 24:29
  Mars opens, it's going to drop back out of
• 24:31
  the Lagrange point, swing towards the Earth,
• 24:33
  uh, get a gravity assist from the Earth, uh,
• 24:35
  and boost off towards Mars. Getting there in
• 24:37
  about September 2027,
• 24:40
  is that right? September 2027. That sounds
• 24:42
  about right, yes. Um, so
• 24:45
  it's going to take the long way around. But
• 24:47
  this is a very economic way of doing things
• 24:50
  and it also opens up the possibility of not
• 24:53
  having to wait for that launch window and
• 24:54
  being at the whims of the weather and stuff.
• 24:56
  You know, the worst case scenario is you're
• 24:58
  launching from one of these launch platform
• 25:00
  areas where they get cyclones, they get
• 25:03
  hurricanes or typhoons, and, um, your
• 25:05
  launch is scrubbed. But the launch site is
• 25:07
  then damaged and by the time it's repaired,
• 25:09
  the launch windows close and you've got to
• 25:10
  wait 26 months and that's not good for
• 25:12
  anybody, um, particularly the staff who are
• 25:14
  waiting to wait on the mission. So if you now
• 25:16
  have something where you can launch missions
• 25:18
  to Mars at almost any time and they can
• 25:21
  just go into a holding orbit, do some extra
• 25:23
  work while they're there because nobody likes
• 25:25
  to be idle, um, and then boosts on off to
• 25:27
  Mars, that's got really interesting
• 25:29
  implications for the future of Mars
• 25:32
  exploration in particular, but also
• 25:33
  potentially exploring the other planets in
• 25:36
  the solar system. As the spacecraft goes out
• 25:39
  there, whilst it hangs around at the L2
• 25:41
  point, it will be earning its keep. It'll be
• 25:43
  doing observations of the solar wind and
• 25:45
  measurements of that which will serve the
• 25:47
  purpose of testing all the equipment on the
• 25:49
  spacecraft and also send back extra
• 25:52
  awesome data, uh, that scientists who study
• 25:54
  space weather can use. And then it'll drop
• 25:57
  and boost off towards Mars. So that's all
• 25:59
  very, very cool. Another aspect of this
• 26:02
  that's really awesome is that it's a
• 26:04
  commercially built spacecraft. So it was
• 26:06
  built by Rocket Lab, who are a big NASA
• 26:08
  partner. And so you've got an entire mission
• 26:11
  to Mars for about US$80
• 26:13
  million. And uh, that includes about $7
• 26:16
  million worth of delays because NASA didn't
• 26:18
  want to launch until Blue Origin had
• 26:20
  confirmed that they could launch a rocket and
• 26:22
  get it back safely. So this is a mission
• 26:25
  to Mars for about US$80
• 26:27
  million, which is
• 26:30
  hugely cheaper than previous
• 26:32
  Mars missions. So we're seeing again,
• 26:35
  not just from the launch, but actually from
• 26:37
  the construction of the spacecraft here, the
• 26:39
  real benefit you get when you finally get to
• 26:41
  the point where you can commercialize space
• 26:44
  travel and space flight. Because by
• 26:47
  bringing in commercial partners, by being
• 26:48
  able to build things using off the shelf
• 26:51
  components, things like that, you bring the
• 26:52
  costs usually down and that enables far more
• 26:55
  science. So that is really exciting and
• 26:58
  reassuring to me as well the fact we'll be
• 27:00
  able to do missions like this in the future
• 27:02
  for cheaper. And uh, the final bit of course
• 27:04
  is what these things are actually going to
• 27:06
  do. There's two spacecraft called Blue and
• 27:08
  Gold who are going to fly in formation when
• 27:10
  they get to Mars, they're going to gradually
• 27:12
  lower their orbits until they're moving on
• 27:13
  identical orbits, one leading the other, a
• 27:16
  bit like ring a ring of roses or something,
• 27:18
  one going around in front of the other one.
• 27:20
  And they're going to spend about 11 months
• 27:22
  studying how Mars's atmosphere
• 27:25
  responds to the solar wind, really trying
• 27:28
  to unpick um, what happens in
• 27:30
  terms of the bleeding away of Mars's
• 27:32
  atmosphere to help us try and get a handle on
• 27:35
  why Mars is no longer the warm, wet
• 27:37
  Mars that it once was, with a thick
• 27:39
  atmosphere and abundant oceans. Yeah, trying
• 27:42
  to get a feel on those processes that
• 27:43
  stripped the atmosphere away to leave it the
• 27:45
  kind of arid husk it is today. So that's
• 27:48
  going to be really cool science. So it's
• 27:49
  like, it's one of these stories where there's
• 27:51
  so many different aspects that are
• 27:53
  individually fascinating. It's hard to know
• 27:55
  where to look first, essentially.
• 27:57
  Andrew Dunkley: Oh yeah, this one's really exciting and it's,
• 28:00
  um, you know, it's going to be in the news
• 28:03
  over the next few years. And those,
• 28:06
  those mysteries that have always surrounded
• 28:08
  Mars, we can get answers to those. That will
• 28:10
  be really valuable information. But it'll
• 28:13
  also close the book on a couple of things
• 28:15
  that we've really been trying to figure out
• 28:18
  for a very, very long time. Because we know
• 28:20
  historically Mars was warm and wet and
• 28:23
  uh, may, uh, have had life.
• 28:28
  What, um, happened? Um, well, there's
• 28:30
  stuff we do know, but there's still
• 28:33
  mysteries. Um, the, uh, I'm just reading here
• 28:36
  the, uh, the green auroras that, uh,
• 28:38
  Mars has, they can't figure that one out. So
• 28:41
  hopefully they'll have an answer for that as
• 28:42
  well. So much more, plenty to learn.
• 28:45
  Jonti Horner: It's also got a really expanded scope to that
• 28:48
  and that we're going to be in a position to
• 28:50
  start actively searching for evidence of life
• 28:53
  on planets beyond the solar system fairly
• 28:54
  soon. I mean, we are trying already. Yeah.
• 28:56
  But as our technology gets better, we'll get
• 28:58
  better and better, uh, looking at these
• 29:01
  planets we find around other stars to look
• 29:02
  for evidence of life. And one of the big
• 29:04
  questions, particularly when it comes to Plan
• 29:06
  M dwarf stars, the little tiny red dwarf
• 29:08
  stars, is whether planets could actually
• 29:11
  hold onto their atmospheres for long enough
• 29:13
  for life to get established and to thrive.
• 29:16
  And that's kind of backed up. If you look at
• 29:17
  the story of the planets around Trappist 1,
• 29:20
  there was huge excitement about those from
• 29:22
  people who were overblowing them as being
• 29:24
  potentially the best targets for the search
• 29:25
  for life elsewhere. Um, when people looked at
• 29:28
  them M with James Webb, they don't have
• 29:31
  atmospheres, which is kind of a problem if
• 29:33
  you want to have liquid water on the surface
• 29:34
  of a planet. Not having an atmosphere is a
• 29:36
  bit of a killer. So this escapade
• 29:39
  mission, by telling us more about the
• 29:41
  process, um, by which Mars lost
• 29:44
  its atmosphere and lost its oceans, that
• 29:47
  data is not just helpful in putting the Earth
• 29:49
  into context. It's not just helpful in
• 29:50
  looking at the history of life on Mars
• 29:52
  potentially, but it's also really useful data
• 29:55
  for, as we look at planets around other stars
• 29:57
  and try and figure out which are the best
• 29:59
  targets for us to look at from the point of
• 30:01
  view of the search for life. It will
• 30:03
  hopefully kind of help us figure out whether
• 30:05
  red dwarf planets are viable or whether we
• 30:07
  should just write off planets around stars
• 30:10
  smaller than a certain mass entirely, when
• 30:13
  we're going to have very limited facility to
• 30:15
  study planets and to look for life on them.
• 30:17
  So it's a mission with a scope beyond just a
• 30:20
  solar system, I think.
• 30:21
  Andrew Dunkley: Yeah, I'm not going to wait for the results.
• 30:22
  I've already decided in my new sci fi novel
• 30:25
  that the planet in question does have an
• 30:28
  atmosphere and it is orbiting a red dwarf.
• 30:30
  So, yes, all bets, all bets are off.
• 30:34
  But, uh, yeah, it's going to be a great
• 30:35
  mission. So we'll, uh, keep an eye on
• 30:38
  everything going on with, uh, that, uh,
• 30:41
  mission to Mars and beyond.
• 30:43
  Uh, let's move on to our
• 30:46
  next story, Jonti, and this involves
• 30:49
  China, the Tiangong Space Station.
• 30:52
  Um, people go to and from that on a fairly
• 30:55
  regular basis. We don't hear much about it,
• 30:57
  but we're hearing about it now because
• 31:00
  there's a few people stranded.
• 31:02
  Jonti Horner: Yes, and it's happened again, of course. We
• 31:04
  had this back in 2024 with the International
• 31:07
  Space Station and the NASA astronauts, Butch
• 31:09
  and Sonny, who were up there for, uh, an
• 31:12
  extended holiday, um, because
• 31:15
  they were stranded there because of the
• 31:16
  problems with getting a vehicle up there to
• 31:18
  bring them home. Effectively,
• 31:21
  it's almost a little bit like history
• 31:23
  repeating itself. So the backstory here is
• 31:25
  that the new crew on the Chinese space
• 31:27
  station Tiangong arrived relatively recently
• 31:30
  on the spacecraft, on the
• 31:33
  delivery vehicle, I guess, on the bus called
• 31:36
  shenzhou21. Yeah, and normally that
• 31:39
  would stay there to bring them back home
• 31:41
  again. And, uh, the previous crew would go
• 31:43
  home on their spacecraft, which was Shenzhou
• 31:45
  20. But Shenzhou 20 was victim of
• 31:48
  a space debris strike and, um, was considered
• 31:50
  unfit to return. People harm. There
• 31:53
  were concerns that it wouldn't get back down
• 31:55
  in one piece, which is very similar, in fact
• 31:57
  to what happened in 2024. And so the crew who
• 32:00
  were on Tiangong got onto Shenzhou
• 32:03
  21, returned home. And that leaves the
• 32:05
  current crew kind of without a lifeboat,
• 32:08
  without a means to ride home safely.
• 32:11
  Andrew Dunkley: Yeah, it's sort of like taking someone else's
• 32:13
  taxi, isn't it?
• 32:14
  Jonti Horner: It is, pretty much. And so they've got to
• 32:15
  wait for the next taxi off the rank. Now the
• 32:18
  reason this is a bit shorter of a segment is
• 32:20
  uh, China are much more close lipped about
• 32:23
  what's happening. Particularly when a story's
• 32:25
  life and we've seen this with their moon
• 32:26
  missions and the Mars missions before, they
• 32:28
  don't tend to tell you much about them
• 32:30
  beforehand. They wait till they're
• 32:31
  successful, then they talk about them. Now
• 32:34
  there are space uh, experts who've been
• 32:36
  interviewed about this and the story is
• 32:38
  apparently that China will typically keep one
• 32:41
  of their Long March 2F rockets, their big
• 32:43
  rockets and a backup Shenzhou
• 32:46
  spacecraft in what, what has been described
• 32:49
  as a state of near readiness. In other words,
• 32:50
  it's not ready to go right now. But in theory
• 32:53
  they should be able to get the lifeboat, uh,
• 32:55
  up to Tiangong within about eight and a half
• 32:57
  days of realizing there's a problem, which is
• 33:00
  probably not hugely comforting to the people
• 33:02
  up there. But in reality eight and a half
• 33:05
  days is a hell of a lot quicker than we got
• 33:06
  Butcher and Sunnyback. Oh yeah. What Chinese
• 33:09
  officials have said is that they've said that
• 33:11
  Shenzhou 22, which is a next tax to go up
• 33:14
  there basically will be launched to Tiangong
• 33:16
  at an appropriate time in the future, which
• 33:19
  is fairly close mouth. But the likelihood is
• 33:21
  that uh, that will go up without a crew.
• 33:24
  It'll be an autonomous thing so that it can
• 33:26
  latch on and give these people a ride home
• 33:28
  when they're ready. So you know, hopefully
• 33:30
  they will get back on schedule and
• 33:33
  they'll certainly have the lifeboat there if
• 33:35
  they need it a lot more quickly than Butch
• 33:37
  and Sunny would with their extended stay and
• 33:39
  their long, long, unexpected fly in, fly out
• 33:42
  adventure.
• 33:43
  Andrew Dunkley: Yes, indeed. Uh, but it's also, it
• 33:46
  also underlines the risks that people take
• 33:49
  going into space. Uh, it is a hostile
• 33:52
  environment and it sounds very much like
• 33:54
  uh, the damage that they suffered on one of
• 33:57
  those shuttles was probably caused by
• 34:00
  something else we sent up there some time in
• 34:02
  the past.
• 34:03
  Jonti Horner: Yeah, um, this is going to be an ever greater
• 34:05
  risk the more stuff we put up there. Uh, I
• 34:07
  mean it goes back to the discussion we had
• 34:09
  about space elevators last week. But
• 34:12
  the more stuff we put up there, the more you
• 34:15
  have to learn to dodge if you are something
• 34:18
  that has people on board. Which probably
• 34:20
  doesn't bode all that well for the plans that
• 34:22
  we kept talking about a few years ago about
• 34:24
  possibly having space hotels up there and
• 34:27
  stuff like that. Because the space
• 34:30
  hotel industry is probably not going to be
• 34:31
  all that impressed with the growing Use of
• 34:34
  commercial space for Internet satellites and
• 34:37
  things like this. So there's really
• 34:40
  interesting challenges in our future. And
• 34:41
  this is just highlighting a problem that will
• 34:43
  become more and more significant in the years
• 34:46
  to come unless we get better legislation
• 34:48
  around the use of space.
• 34:51
  Andrew Dunkley: And the, um, the rules
• 34:54
  should consider, you know, cleaning up your
• 34:57
  own act. Uh, I know, I know. There is
• 35:00
  a code requiring you to, you know, look
• 35:03
  after your own stuff when it's been
• 35:05
  dealt with or you finished using it or
• 35:07
  whatever and deorbit it and burn it up. But
• 35:10
  that's another, that's creating another
• 35:12
  problem because all this stuff that burns up
• 35:13
  ends up staying in the upper atmosphere. And
• 35:16
  we don't know what that's going to do in the
• 35:17
  future.
• 35:18
  Jonti Horner: No, it's awfully complex. And I mean, the
• 35:20
  other thing is that whole thing about bring,
• 35:22
  bring stuff back into the atmosphere to
• 35:24
  declutter space is all well and good, but if
• 35:27
  a satellite gets smashed by a bit of space
• 35:29
  debris, you can't control where the debris
• 35:31
  goes. It isn't really the responsibility of
• 35:34
  the people whose satellite was smashed. You'd
• 35:36
  have thought to account for all of the debris
• 35:38
  that was generated by their satellite being
• 35:40
  hit by something that wasn't theirs. I mean,
• 35:42
  that would be an interesting claim to put in
• 35:44
  for the insurance. Normally if you're in a
• 35:45
  bit of a car bump, you claim from the other
• 35:48
  driver's insurance. That's how it works. But
• 35:51
  a lot of the debris up there isn't like it's
• 35:53
  cataloged, that this is a property of the US
• 35:55
  this is the property of spare techs. It's a
• 35:57
  bit of debris. There's large amounts of
• 35:59
  debris up there that is too small for us to
• 36:00
  effectively track.
• 36:02
  Andrew Dunkley: Yeah, well, things as small as paint flicks,
• 36:04
  but they're moving at thousands of kilometers
• 36:07
  an hour.
• 36:07
  Jonti Horner: Yeah, it's challenging. And I think we
• 36:10
  take space and our use of space for granted
• 36:13
  nowadays. It's not like the 1960s where
• 36:15
  people accepted that human space flight was
• 36:18
  dangerous. People will die. We just get
• 36:21
  on with it. There's been a big transition. I
• 36:23
  think that was a big part of why we
• 36:26
  stopped going back to the moon, or rather why
• 36:28
  it's taken so long to go back, should I say?
• 36:30
  And similarly, it's why the shuttle program
• 36:31
  eventually came to an end. That shift in
• 36:34
  public consciousness from when the Challenger
• 36:36
  disaster happened, when people were like,
• 36:38
  this is very sad, but we need the space
• 36:40
  shuttle to when the second disaster happened,
• 36:43
  and that was too much. We've had this
• 36:46
  shift in the public conscious and it's Kind
• 36:48
  of grounded in that idea that space is easy
• 36:50
  and it really isn't. This is just a reminder
• 36:51
  that space is hard. There are going to be
• 36:54
  problems in the future. And it's an
• 36:56
  interesting challenge to balance off the
• 36:58
  needs of commercial enterprise and the needs
• 37:01
  of human spaceflight and the regulation
• 37:03
  involved, when pretty much everybody involved
• 37:05
  benefits from it not being that regulated. So
• 37:08
  there's not much of an incentive. It's a bit
• 37:09
  like asking fossil fuel companies to
• 37:11
  legislate about climate change or cigarette
• 37:13
  companies to legislate about cancer.
• 37:15
  Andrew Dunkley: Yeah.
• 37:16
  Jonti Horner: It's not in their interest to do so.
• 37:18
  Andrew Dunkley: No. No. But we do wish the Chinese, uh,
• 37:22
  astronauts well. And I'm sure they'll be
• 37:24
  home pretty soon. We hope so. Anyway.
• 37:27
  Um, I just thought I'd better check because,
• 37:30
  uh, we don't call Russian astronauts
• 37:33
  astronauts. They're cosmonauts. Chinese
• 37:35
  astronauts are officially astronauts, but
• 37:36
  they're also known as tychonauts.
• 37:39
  Jonti Horner: Yeah, it's a really interesting one. And I'm
• 37:42
  not an. Is it etymologist or entomologist.
• 37:44
  One of them is about words and one of them's
• 37:46
  around beetles. But I'm not into the science
• 37:48
  of the study of words. But there
• 37:51
  has been this idea of every nation
• 37:54
  having its own unique name for those that
• 37:56
  they sent to space. Um, where you have
• 37:59
  cosmonauts and tychonauts. It does make me
• 38:01
  wonder if Australian ones will be skipping
• 38:03
  out. So, hoppy notes or, um, I'm thinking
• 38:06
  diggernauts. Yeah. Drop by notes.
• 38:09
  There was a story which is sufficiently out
• 38:11
  of my field that we're not talking about it,
• 38:13
  but there was a story that cropped up on the
• 38:15
  BBC last week that somebody has discovered
• 38:17
  droc crop fossils. Drock
• 38:20
  Drop croc fossils. So anybody
• 38:23
  who's been to Australia or knows Australians
• 38:25
  knows about drop bears, which are a terrible
• 38:28
  pest. And we have to deal with them. Um, we
• 38:30
  do. They're a nightmare. You should look at
• 38:31
  the Australian museums. Drop bears.
• 38:33
  Andrew Dunkley: I mean, people worry about spiders and snakes
• 38:35
  and. And jellyfish. No, that's the drop
• 38:37
  bears.
• 38:37
  Jonti Horner: Something to share on the Facebook group
• 38:40
  would be the Australia Museum's drop bear
• 38:42
  page, because they've got a location map
• 38:45
  for them and a large description. So for
• 38:46
  those interested in drop bears can really
• 38:49
  strongly recommend that. But there was an
• 38:50
  article came out in the BBC, um, and I think
• 38:53
  a few other reputable science journalism
• 38:55
  outlets last week talking about fossilized
• 38:58
  drop crocs. So the idea that there was a
• 39:01
  species of crocodile in Australia a few tens
• 39:03
  of millions of years ago that used to climb
• 39:06
  up Trees and drop hunt in the same way
• 39:08
  leopards do. So you'd have crocodiles jumping
• 39:10
  out of trees onto their prey. Oh, my word.
• 39:12
  So, yeah, yeah, Dropper nauts would probably
• 39:15
  be an appropriate Australian.
• 39:17
  Andrew Dunkley: Yeah, I'm, um, actually, I'm actually
• 39:19
  looking.
• 39:20
  Jonti Horner: At the Drop Bear map. It's upload, isn't it?
• 39:25
  Andrew Dunkley: I love the, the, the, the, the. The shape of
• 39:28
  the location in Central Australia.
• 39:29
  Jonti Horner: That's. Yeah, that's a river.
• 39:31
  Absolutely. So always remember to wear your
• 39:34
  hat with the corks on.
• 39:35
  Andrew Dunkley: Oh, yeah, that keeps them away. They don't
• 39:37
  like corks. Okay, moving, uh,
• 39:40
  on. This is Space Nuts with Andrew Dunkley
• 39:42
  and Professor Jonti Horner.
• 39:49
  Space Nuts to our
• 39:52
  final story. And, uh, this is, this is a bit
• 39:54
  of a fun one. Uh, the Pleiades.
• 39:57
  Jonti Horner: Um, what.
• 39:59
  Andrew Dunkley: What's going on with them?
• 40:01
  Jonti Horner: Well, the Pleiades are.
• 40:02
  Andrew Dunkley: Oh, oh, yeah, sorry, sorry. No,
• 40:05
  I just. The Pleiades are the subject, but
• 40:07
  the, but the topic is actually chasing stars
• 40:10
  using gyochronology.
• 40:13
  Jonti Horner: Gyrochronology.
• 40:14
  Andrew Dunkley: Gyrochronology, yes.
• 40:15
  Jonti Horner: A couple of other things. It's the beauty of
• 40:17
  being able to bring together
• 40:20
  different fields of astronomy with different
• 40:21
  data. It actually ties into a fabulous
• 40:24
  Australian project that I was part of for a
• 40:26
  good long time, uh, that I need to get back
• 40:29
  involved with at some time, to be honest,
• 40:30
  that I think Fred's been involved with a bit
• 40:32
  as well, called Galah, which is Galahia
• 40:34
  archeology with Hermes. And this is, uh, a
• 40:37
  means by which we can look for stars that
• 40:39
  form together and do archeology that digs
• 40:42
  into the history of star formation in the
• 40:44
  Milky Way by looking at the spectra of stars,
• 40:46
  figuring out their compositions, looking at
• 40:48
  the abundances of elements within those stars
• 40:51
  to find their stellar twins, the stars that
• 40:53
  they formed with long ago that have that same
• 40:56
  chemical fingerprint of their original
• 40:58
  formation. This story links to that, but it's
• 41:01
  not actually using Galar data. It's using a
• 41:03
  variety of other data. The story is that we
• 41:06
  have the most famous
• 41:09
  star cluster in the night sky, the Pleiades,
• 41:11
  the seven sisters to people in Japan. This
• 41:14
  was Subaru. But basically every
• 41:17
  culture across the planet can see the
• 41:19
  Pleiades, ah, within about 25 degrees
• 41:22
  of the celestial equator. They're not very
• 41:25
  far from the ecliptic. In fact, you often see
• 41:26
  beautiful photos of the Moon or the planets
• 41:29
  near the Pleiades. So they're visible from
• 41:32
  basically the entire inhabited surface of the
• 41:34
  Earth. Uh, they're very beloved of people.
• 41:36
  There's a lot of wonderful cultural stories
• 41:38
  that talk about them. There was a fabulous
• 41:40
  study looking at the traditional knowledge of
• 41:43
  the traditional owners here in Australia from
• 41:45
  some of the groups who talked about the
• 41:48
  Pleiades being protected by the bright star
• 41:50
  in Taurus, Aldebaran, who was a wise woman,
• 41:53
  protecting these young women from a fairly.
• 41:56
  A man with fairly voracious appetites in the
• 41:58
  form of Beetlejuice in Orion and Betelgeuse,
• 42:01
  and Aldebaran fighting using fire magic, and,
• 42:04
  um, the magic building up and flaring off and
• 42:07
  them having this fight, which is a fabulous
• 42:09
  story, but it also ties into the fact that
• 42:11
  both Betelgeuse and Eldebaran are variable
• 42:14
  stars. And, um, this story is
• 42:16
  taking their variability into account in part
• 42:19
  of the folklore and the storytelling of what
• 42:22
  is culturally right and wrong, what is the
• 42:23
  right way to behave, and in doing so,
• 42:26
  encoding astronomical data. So that's a study
• 42:28
  that, uh, my colleague Duane Hamacher, down
• 42:30
  at the University of Melbourne was telling me
• 42:32
  about, that he was involved with, which is
• 42:34
  fabulous work. So the Pleiades
• 42:37
  are really, uh, important to cultures all
• 42:39
  across the globe. They're very beloved.
• 42:40
  They're very easy to see with the naked eye.
• 42:42
  Depending on how good your eyesight is and
• 42:44
  how good your location is, most people will
• 42:46
  see six, seven or eight of them. You know, I
• 42:48
  can normally pick up eight or nine on a
• 42:50
  really good dark site, six or seven when it's
• 42:52
  less so. Uh, and that's why, for a lot of
• 42:54
  people, they're considered the Seven Sisters.
• 42:56
  There is a guy in Italy who used to claim he
• 42:59
  could see 82 of these stars with the unaided
• 43:01
  eye. And I think it's fair to say that nobody
• 43:03
  believed him. If you look at the cluster with
• 43:05
  binoculars or a telescope, you see far more.
• 43:07
  So the stars we see with the naked eye are
• 43:09
  the ones that are the superstars. They're the
• 43:11
  most massive, the most luminous, these
• 43:13
  bright, beautiful blue stars.
• 43:16
  Now, what we know about star clusters like
• 43:17
  the Pleiades, like the Hyades, like Prispe,
• 43:20
  the Beehive, is that these agglomerations of
• 43:23
  stars are stars that formed in the same
• 43:24
  stellar nursery. They were all born together,
• 43:27
  but the cluster does not have enough mass
• 43:29
  that it will stay discrete and held together
• 43:32
  forevermore under gravity. Um,
• 43:35
  unlike globular clusters, which are as old as
• 43:38
  the Galaxy and are very different, they're
• 43:40
  kind of a million stars packed into a small
• 43:42
  space. Open clusters are typically a few
• 43:44
  hundred or a few thousand stars. And so what
• 43:46
  tends to happen a bit like young kids is, you
• 43:49
  know, they hang around Together while they're
• 43:50
  at school, while they're at nursery. But then
• 43:51
  as they move into their adult lives, they
• 43:53
  disperse off and go their separate ways. Um,
• 43:55
  and what that means for clusters like the
• 43:57
  Pleiades is gradually the stars towards
• 44:00
  the outer edges of the cluster, uh, will
• 44:02
  gradually get nudged and tugged. So they fall
• 44:04
  away from the cluster, start to move freely
• 44:06
  through the galaxy, separate to the cluster,
• 44:08
  and the cluster disperses and it kind of gets
• 44:11
  whittled away from the outside in. And what
• 44:13
  we see with the Pleiades on the sky is a core
• 44:16
  kernel, the very central area, which has the
• 44:18
  most massive stars in all hanging around. And
• 44:21
  the idea is that when the Pleiades were
• 44:22
  younger, there were more members still bound
• 44:25
  to the cluster. The cluster was bigger. And
• 44:26
  the cluster's been shedding members over
• 44:28
  time, and that's fairly well established. But
• 44:31
  it's really interesting to think about where
• 44:33
  those members have gone. You know, it's like
• 44:35
  looking back at a band from youth. What did
• 44:37
  they do now? Where are they now? Those old TV
• 44:39
  shows, Where are the former members of the
• 44:41
  Pleiades? Now, this has led to the concept
• 44:44
  of the greater Pleiades complex. So if you
• 44:47
  could, with good enough precision, get lots
• 44:50
  of data about all the stars in the sky, you
• 44:52
  could, in theory, identify those ones that
• 44:54
  formed in the Pleiades but have disappeared.
• 44:57
  And, um, that's what this work has tried to
• 44:59
  do. There have been previous estimates that
• 45:01
  have just looked at, uh, the positions on the
• 45:03
  sky and the motion of the stars to see if
• 45:05
  that motion is compatible with them having
• 45:07
  formed in the Pleiades. Are they moving
• 45:09
  through space at about the same speed as the
• 45:11
  Pleiades, but moving away from the Pleiades
• 45:13
  at such a speed that they would have been
• 45:16
  near the Pleiades when they formed? Now, that
• 45:18
  was problematic because it will capture a lot
• 45:20
  of stars that just happen to be in the
• 45:22
  vicinity of the Pleiades when they formed,
• 45:24
  but were already there. You know, they were
• 45:26
  near the star forming region, but they were
• 45:27
  not involved. I guess it's a bit like, you
• 45:29
  know, trying to figure out all the babies
• 45:31
  that were born in a hospital on a certain day
• 45:33
  by saying anything that was in a, within a
• 45:35
  kilometer of the hospital could potentially
• 45:37
  have been a baby that was born there. But
• 45:39
  you've got a lot of people commuting past on
• 45:40
  the highway at the time. Just so happens
• 45:44
  what this new study has done is it's taken
• 45:47
  data on the stars from NASA's Exoplanet
• 45:49
  Survey Satellite tests. The transiting
• 45:51
  exoplanet Survey satellite that's been
• 45:53
  scouring basically the entire sky gives you a
• 45:56
  wealth of data on how stars behave. You've
• 45:58
  got the Gaia spacecraft, which is a
• 46:01
  European Space Agency mission that has
• 46:03
  stopped observing now, but is still providing
• 46:05
  lots of data updates. And we're looking
• 46:06
  forward to BR4 from that next year from the
• 46:09
  exoplanet side of things. But Gaia has given
• 46:12
  us incredibly precise positions on the sky,
• 46:15
  incredibly precise distances, and
• 46:18
  incredibly precise movement information about
• 46:21
  the stars. So we know very accurately where
• 46:23
  they are in space and how they're moving. And
• 46:26
  the team behind this work have brought into
• 46:28
  it the third bit of information, which is
• 46:31
  gyrochronology. So this is an attempt
• 46:34
  to figure out the edges of stars. And once
• 46:36
  stars are on the main sequence, once they're
• 46:38
  in the prime of life, it's very challenging
• 46:41
  to figure out how old they are because they
• 46:43
  sit there basically doing very little,
• 46:45
  changing very little. Perry the Platypus,
• 46:47
  he's a platypus. They don't do much. It's
• 46:49
  that same kind of idea, just sits on the main
• 46:52
  sequence, trundling along, barely changing.
• 46:54
  Now, there are means like
• 46:57
  asteroseismology, measuring the wibbling and
• 46:59
  the wobbling and the starquakes on a star
• 47:01
  that can tell you a lot about its interior
• 47:03
  and allow you to infer an edge. And that's
• 47:05
  what some of my colleagues at UNISQ do. But
• 47:08
  that's very time consuming and challenging.
• 47:10
  So you kind of have to do one star at a time
• 47:12
  and dedicate a lot of observations to do
• 47:14
  this, because you've got to measure all the
• 47:15
  different frequencies at which that star
• 47:17
  vibrates and wobbles. So that's good for
• 47:19
  individual stars, but it's not good for a
• 47:22
  population survey like this. So going
• 47:25
  back about 20 years, a couple of researchers
• 47:27
  noticed that for stars where we had
• 47:30
  relatively good understanding of their ages,
• 47:33
  that were less massive than a spectral class
• 47:35
  of F8. So these are sun like stars, or a
• 47:37
  little bit more massive, going all the way
• 47:39
  down to red dwarfs. They found that there is
• 47:42
  a broad relationship that the older the star
• 47:44
  is, the slower it spins. And this
• 47:47
  makes sense. You know, our sun is shedding
• 47:49
  angular momentum with the solar wind
• 47:52
  as material is flung off. So it's gradually
• 47:54
  spinning down and it's a very, very, very
• 47:57
  slow process. But given that stars live very
• 47:59
  long lives, it's something that is
• 48:01
  quantifiable and measurable. So the idea
• 48:04
  here is that if you find stars that are
• 48:06
  spinning quickly, then they are probably
• 48:08
  young. And so the team involved with this
• 48:11
  study, took this master list of all the
• 48:13
  stars that have positions and velocities
• 48:17
  compatible with them being near the Pleiades.
• 48:19
  When the Pleiades formed and did an edge
• 48:22
  check on them, they ID'd them effectively.
• 48:24
  They said, how old are you? Measured the spin
• 48:27
  rates, which is the kind of information you
• 48:28
  can get from missions like tess. And, um,
• 48:31
  they set a limit that I think the SARS had to
• 48:33
  be spinning with rotation rates of 12 days or
• 48:36
  shorter to be young enough.
• 48:38
  That allowed them to filter the list down
• 48:40
  significantly and left them just over
• 48:43
  3,000 candidate stars that are
• 48:46
  probably members of this greater Pleiades
• 48:48
  complex. And those stars are spread on all
• 48:50
  over the night sky. They're concentrated
• 48:53
  through the Milky Way, through the plane of
• 48:54
  the galaxy. And that's perfectly making
• 48:56
  sense, because star clusters tend to form
• 48:58
  very close to the plane of the galaxy. They
• 49:01
  tend to be dynamically kind of cold. They
• 49:03
  tend to be on very flat orbits. So these
• 49:06
  things have spread out along the plane of the
• 49:08
  galaxy in both directions, away from the
• 49:09
  Pleiades in the sky. But because some of
• 49:11
  these stars are relatively nearby to us, some
• 49:14
  are passing above or, uh, below us. So
• 49:16
  basically, any direction in the sky that you
• 49:18
  look, you might see a star that was born with
• 49:21
  the Pleiades, um, tens of millions of years
• 49:24
  ago. It used to be that the Pleiades were
• 49:26
  said to be about 65 million years old. I
• 49:28
  think the accepted wisdom now is that they're
• 49:30
  about 100 million years old. And, uh, that
• 49:32
  gives you a lot of time to move a very long
• 49:34
  way away from the cluster if you've escaped.
• 49:36
  Yeah. So these stars are just spread all
• 49:38
  across the sky, and it's a really lovely
• 49:41
  insight into the lives of these clusters
• 49:44
  and to the way that we can do kind of
• 49:46
  stellar and galactic archeology effectively.
• 49:49
  We can get insights into the formation
• 49:51
  history of our galaxy and how clusters form
• 49:53
  and evolve. It's really beautiful. And it is.
• 49:56
  You know, my partner's big into archeology.
• 49:59
  She loves watching Time Team with Tony
• 50:00
  Robinson. And this is effectively like a Time
• 50:02
  Team episode in the sky. Hm.
• 50:05
  Andrew Dunkley: It is fascinating. We don't think about it
• 50:07
  much. We look up. Most people probably just
• 50:09
  look up at the stars and go, ah, they're
• 50:10
  pretty. But they don't think about how
• 50:13
  over time they've moved around. And it goes
• 50:16
  back to a story Fred and I talked about more
• 50:19
  than once, and that is that, uh, our
• 50:22
  son was probably a member of a
• 50:25
  binary, um, and had a sister star
• 50:29
  or a twin that we are still looking for.
• 50:32
  It's out there somewhere, probably, but we
• 50:34
  haven't found it yet. But, um, yeah,
• 50:37
  uh, it's a fascinating study and I, uh, like
• 50:39
  the sound of it. You can read all about
• 50:41
  it@space.com or you can go to
• 50:43
  abc.net au on their science
• 50:46
  pages and check that out. Uh,
• 50:50
  we are done. Jonti, thank you so much.
• 50:52
  Jonti Horner: That's all good. And sorry for the unexpected
• 50:54
  interruption in the middle there, but
• 50:55
  insurance companies got to do what insurance
• 50:57
  companies got to do, unfortunately.
• 50:59
  Andrew Dunkley: They have got to do that, whatever they do.
• 51:02
  I thought of another name for an Australian
• 51:04
  astronaut.
• 51:05
  Jonti Horner: Yes.
• 51:05
  Andrew Dunkley: You ready?
• 51:06
  Jonti Horner: Yeah.
• 51:06
  Andrew Dunkley: A Yobo Nord. I
• 51:09
  reckon that would. That'd probably be a
• 51:11
  winner.
• 51:12
  Jonti Horner: Well, you recruit that. Recruit them from.
• 51:14
  You could have Larry Connaughts. Larry
• 51:16
  Connect. Uh, or Boganuts.
• 51:19
  Andrew Dunkley: Boganauts.
• 51:20
  Jonti Horner: Yes.
• 51:20
  Andrew Dunkley: Well, we have a shire west of us called Bogan
• 51:23
  Shire, so.
• 51:23
  Jonti Horner: And of course, if you. If you send any pets
• 51:26
  to space, you could probably have blueynauts
• 51:28
  as well.
• 51:28
  Andrew Dunkley: Bluey notes.
• 51:29
  Jonti Horner: Yes.
• 51:29
  Andrew Dunkley: That'd be popular. And you can't wear boots
• 51:32
  to space. You got to wear thongs.
• 51:33
  Jonti Horner: Yes.
• 51:34
  Andrew Dunkley: Which everyone else calls flip flops or
• 51:36
  jandals or something, but we've somehow
• 51:38
  managed to turn a pair of underpants into
• 51:40
  footwear.
• 51:41
  Jonti Horner: Yeah. Anyway, what's a constant source of
• 51:43
  confusion for shop owners in the uk? When
• 51:45
  Aussies came in and went into a shoe shop
• 51:47
  asking where they keep their thongs. And, um,
• 51:49
  it was always quite entertaining seeing
• 51:51
  people's faces as the staff kind of react.
• 51:55
  Andrew Dunkley: That's a whole different story. Um, anyway,
• 51:58
  Jotty, thank you, uh, so much.
• 51:59
  Jonti Horner: It's been a pleasure. It's an absolute
• 52:00
  pleasure. Thank you for having me. Always.
• 52:02
  Good.
• 52:03
  Andrew Dunkley: Uh, John T. Horner, professor of Astrophysics
• 52:05
  at the University of Southern Queensland. And
• 52:07
  thanks to Huw in the studio, who
• 52:10
  didn't much help today because, you know,
• 52:12
  he's got a second job. Uh, he's an Uber
• 52:14
  driver, and he got a text to pick
• 52:17
  up some Chinese astronauts from the
• 52:20
  Tiangong Space Station, so he's on his way.
• 52:23
  Uh, don't forget to visit us online at, uh,
• 52:26
  Facebook, the Space Nuts podcast group, or
• 52:28
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• 52:30
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• 52:33
  website and have a look around while you're
• 52:34
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• 52:36
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• 52:38
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• 52:40
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• 52:44
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• 52:45
  Uh, that's Space Nuts IO and from
• 52:48
  me, Andrew Dunkley. Thanks for your company.
• 52:50
  We'll see you real soon on the next episode
• 52:52
  of Space Nuts. Bye. Bye.
• 52:54
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