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Cosmic Q&A: From Redshift to the Moon's Hidden Temperatures · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Andrew Dunkley: Hello again. Thank you for joining us on a Q
• 0:01
  and A edition of Space Nuts. This is where
• 0:04
  the audience asks us questions, we scratch
• 0:06
  our heads and it's all over in about a
• 0:08
  minute. Um, but, uh, if we are
• 0:11
  to answer questions, we may well, um,
• 0:14
  answer, um, the question as to how they're
• 0:16
  going to save the Swiss. Uh, the
• 0:19
  Swift Observatory, which as
• 0:22
  you might recall in a previous episode, was
• 0:24
  under threat of, um, you know, coming back
• 0:26
  into the Earth's atmosphere and being lost
• 0:28
  forever. Well, uh, James, who asked the
• 0:31
  question, is going to be in for a bit of a
• 0:32
  shock on that one. Uh, also a, uh, follow
• 0:35
  up on Redshift. We're going to look at
• 0:37
  temperatures of the moon and a white
• 0:40
  hole, black hole merger. What
• 0:43
  would be the effect? Fred Watson knows, we'll
• 0:45
  ask him on this edition of space
• 0:47
  nuts.
• 0:48
  Generic: 15 seconds. Guidance is internal.
• 0:51
  10, 9. Ignition
• 0:53
  sequence start.
• 0:54
  Professor Fred Watson: Uh, space nuts.
• 0:55
  Generic: 5, 4, 3, 2. 1, 2, 3, 4,
• 0:58
  5, 5, 4, 3, 2, 1.
• 1:00
  Andrew Dunkley: Space nuts.
• 1:02
  Generic: Astronauts report at Beales.
• 1:04
  Andrew Dunkley: And joining us to unrattle all of those
• 1:07
  rattling questions is Professor Fred Watson
• 1:10
  Watson, Astronomer at large. Hello,
• 1:11
  Fred Watson.
• 1:12
  Professor Fred Watson: Hello, Andrew. Fancy seeing you.
• 1:14
  Andrew Dunkley: Long time, long time no see. Yes,
• 1:17
  um, a question without notice.
• 1:20
  Do you always record on the same day and
• 1:22
  time? No, no, we
• 1:25
  don't. No. Uh, it's never that
• 1:28
  easy. That was an easy one to
• 1:30
  answer.
• 1:31
  Professor Fred Watson: Is that from our live, uh, audience?
• 1:33
  Andrew Dunkley: Yes, that's from Moose. G', Day, Moose.
• 1:36
  Yeah, but no, no, we don't. Um,
• 1:39
  it all comes down to who's available
• 1:42
  on whatever given day. And uh,
• 1:45
  today was the day. But, uh, no, it's, it's,
• 1:48
  it sort of jumps around sometimes we have to
• 1:50
  double up. In fact, um, this is the
• 1:53
  first time we've actually recorded together
• 1:56
  for over a month because Fred Watson
• 1:58
  was travelling and we had to double up
• 2:01
  for um, quite a few weeks to get ahead. And
• 2:04
  um, we didn't quite make it, which is why
• 2:06
  Jonty covered things for the last couple of
• 2:08
  weeks. But, uh, we generally try to do
• 2:11
  it in the morning so that we can catch the
• 2:14
  evening viewers in the United States, which
• 2:18
  works, um, out pretty well for most. But then
• 2:20
  most of the people in this part of the world
• 2:22
  are at work.
• 2:23
  Professor Fred Watson: So it's lose, lose.
• 2:25
  Andrew Dunkley: Basically can't cater for the entire world
• 2:28
  at one given moment. But that's, that's,
• 2:30
  that's the way it goes. If we could sort of
• 2:32
  just have one time zone with daylight
• 2:34
  everywhere all the time, it would make it
• 2:35
  easier. But, um, yeah, they're still working
• 2:37
  on that and I'm not joking, they are still
• 2:39
  working on that. They're trying to put up
• 2:41
  these big mirrors and I don't know what else.
• 2:43
  It's weird. Um, do you want to
• 2:46
  tackle some questions, Fred Watson?
• 2:49
  Professor Fred Watson: Yes, please.
• 2:49
  Andrew Dunkley: Thank you.
• 2:50
  Andrew Dunkley: Um, actually, we do have a live question
• 2:53
  straight up, so we'll might jump straight at
• 2:55
  that one.
• 2:56
  What are your thoughts on the red dots as
• 2:58
  seen by the James Webb Telescope?
• 3:00
  Professor Fred Watson: Asks.
• 3:01
  Andrew Dunkley: Good.
• 3:02
  Andrew Dunkley: Interestingly, they're in the news at the
• 3:04
  moment because, uh, there was a storey I only
• 3:06
  read just before we came on live to suggest
• 3:09
  that they think they're about to witness a
• 3:12
  red dot merger.
• 3:14
  Interestingly, yeah.
• 3:17
  Professor Fred Watson: So they're being well studied. Uh, and
• 3:20
  one of them in particular,
• 3:24
  uh, which has a name, I think it's called
• 3:27
  BH1. BH
• 3:31
  is an abbreviation for black hole star number
• 3:34
  one. Uh, and, um,
• 3:37
  this is a little red dot that, unlike many
• 3:40
  of the other ones, is in a
• 3:42
  relatively empty environment. So,
• 3:46
  uh, let's just recap. What are little red
• 3:48
  dots? They're what the penetrating power of
• 3:51
  the James Webb Telescope has revealed for the
• 3:53
  first time, uh, in the early universe, uh, at
• 3:56
  a time when the universe was only, you know,
• 3:59
  a few hundred million years old, we see these
• 4:01
  objects which have now got the name of little
• 4:03
  red dots. Um, they're compact,
• 4:06
  uh, and they are quite
• 4:09
  bright in terms of the amount of energy
• 4:12
  that they, uh, emit. And I think
• 4:15
  BH1, if I remember
• 4:17
  rightly, it's 100 billion times brighter
• 4:20
  than it should be. Whoa. Uh, and.
• 4:23
  But that's leading to
• 4:26
  the suggestion that what we're seeing here
• 4:30
  is a star, which, uh,
• 4:33
  is basically a cloud of gas with
• 4:36
  a supermassive black hole at its centre.
• 4:39
  So if you think about, uh, our knowledge of
• 4:42
  galaxies, most of which seem to have
• 4:44
  supermassive black holes at their centre,
• 4:46
  they're made of stars. Uh, that star
• 4:49
  formation process takes place over billions
• 4:51
  of years. Um, and we used to think that
• 4:54
  it took a long time for these black holes to
• 4:56
  become supermassive by, you know, them
• 4:59
  being basically, uh, gobbling up each other,
• 5:03
  uh, gobbling up material so that they became
• 5:05
  supermassive. But we see supermassive black
• 5:08
  holes now so early in the universe. And it
• 5:10
  looks as though BH
• 5:13
  got one at its centre. I think it's 50,000 or
• 5:15
  thereabouts times the mass of the sun. Can't
• 5:17
  remember the details. Um, I've had an
• 5:19
  operation since I read all that. Uh,
• 5:24
  so, um, um, the evidence seems
• 5:27
  to be that we are seeing a new class of
• 5:29
  object, uh, essentially a galaxy.
• 5:33
  Something not the size of a galaxy because
• 5:35
  Their dimensions are kind of solar system
• 5:37
  size. They're much bigger than the solar
• 5:39
  system, but they're clouds of gas.
• 5:42
  And we think that they are energised
• 5:45
  by the accretion disc. The way material is
• 5:48
  swirling around the black hole at their
• 5:51
  centre and that's raising temperatures in the
• 5:54
  middle to very high degrees until you get
• 5:56
  very high levels of energy emission, which is
• 5:59
  why they're said to be 100 billion times
• 6:01
  brighter than they should be. So it looks as
• 6:04
  though we're on the track of identifying
• 6:06
  these little red dots as something quite new
• 6:08
  and kind of unexpected. I'm sure they were
• 6:11
  predicted that we'd find, uh, stars
• 6:14
  made basically of nothing but gas in a black
• 6:17
  hole, uh, rather than, you know, other
• 6:19
  stars. Uh, and um, that
• 6:22
  seems to be what they are. So. Yeah, watch
• 6:25
  this. Space though. Um, you know.
• 6:29
  Yes, Moose, thanks.
• 6:30
  Andrew Dunkley: No, it wasn't Moose. It was good. Sorry, but
• 6:32
  thanks for the question.
• 6:33
  Uh, we've got an audio question now. This is
• 6:36
  from James.
• 6:37
  Andrew Dunkley: Hi, this is James in high western England.
• 6:41
  So as of 6 July, there's a
• 6:43
  spacecraft called Link which will boost the
• 6:46
  decaying orbit of the Swift satellite.
• 6:50
  What will it do to boost the orbit and what
• 6:53
  even does that mean, to boost an
• 6:55
  orbit? Um, I m. Guess I assume
• 6:58
  that pushing it from underneath might not
• 7:02
  be the answer. So look forward to
• 7:04
  hearing how it might actually do that.
• 7:07
  Thanks, James.
• 7:09
  Andrew Dunkley: Thank you, James. Hope all is well in, I
• 7:11
  think you said, Howick in the uk.
• 7:13
  Professor Fred Watson: High Wycombe.
• 7:14
  Andrew Dunkley: High Wycombe.
• 7:15
  Andrew Dunkley: All right.
• 7:16
  Andrew Dunkley: Okay. Could have been either.
• 7:19
  Um, We've got some bad news for you, James,
• 7:22
  I'm afraid, haven't we, Fred Watson?
• 7:24
  Professor Fred Watson: Yeah. So, uh,
• 7:27
  it's really sad because, um, this
• 7:31
  project has been a bit of a poster child
• 7:34
  for NASA because normally their projects take
• 7:37
  decades to come into fruition. But
• 7:40
  they tasked company, uh,
• 7:43
  something like a. With a year's notice or
• 7:46
  something, uh, to develop
• 7:49
  a spacecraft, uh, and actually
• 7:53
  um, basically work out how you could rescue
• 7:56
  the Swift spacecraft. So the storey is Swift
• 7:59
  is uh, an elderly SpaceCraft
• 8:02
  launched in 2004 to study gamma ray
• 8:05
  bursts. But it's been so successful,
• 8:07
  uh, that there was a uh, real
• 8:10
  uh, I guess desire to uh, to save
• 8:13
  it because its orbit is decaying.
• 8:16
  And as of later this year we expect
• 8:19
  it, Its orbit will actually get
• 8:22
  so much atmospheric drag that it will decay
• 8:24
  very quickly and the spacecraft, the Swift
• 8:27
  spacecraft will burn up in the atmosphere.
• 8:30
  So, um, the Link mission, uh,
• 8:32
  was a joint, um, project
• 8:35
  between NASA and a company called
• 8:38
  Catalyst, Catalyst Space. Uh,
• 8:40
  and indeed the Link spacecraft was launched
• 8:43
  on July 3
• 8:46
  with every intention of rendezvousing with
• 8:49
  the Swift spacecraft and lifting its orbit.
• 8:52
  And I'll get onto that in a minute because
• 8:54
  that's basically James's question.
• 8:57
  But what happened was um, they had an
• 8:59
  attitude control issue. Uh,
• 9:02
  and so very quickly the,
• 9:05
  and probably within weeks link, uh,
• 9:09
  the spacecraft that was going to save Swift
• 9:11
  just started tumbling out of control.
• 9:14
  Um, and we got an announcement uh,
• 9:17
  very soon after that that the spacecraft
• 9:20
  would not capture or boost the Swift
• 9:22
  satellite's altitude as planned.
• 9:25
  Um, I think
• 9:28
  they're still attempting
• 9:31
  to rendezvous with Swift. In other
• 9:34
  words to bring the Link spacecraft close to
• 9:37
  Swift just to cheque that
• 9:39
  all their capabilities in terms of
• 9:42
  rendezvous uh, are working. But
• 9:45
  because of this out of control tumbling,
• 9:48
  um, they're not going to be able to do
• 9:50
  anything on that. Um,
• 9:53
  so um, it's turning into a
• 9:56
  mission that is a face saving mission in a
• 9:59
  way. Uh, there is a nice piece on
• 10:02
  our own friend Universe today. Uh, they've
• 10:05
  got a nice piece on it called NASA Announces
• 10:07
  Next Steps for Swift Rescue Mission. And it
• 10:10
  has a lot of quotes from uh, people like
• 10:13
  uh, the NASA administrator Jared Isaacman,
• 10:15
  uh, and, and other people involved, uh,
• 10:18
  Catalyst Space have released a statement,
• 10:21
  um, all of which is you know, basically
• 10:24
  saying that they, they'd hope for more
• 10:26
  science from Swift. Um, I think
• 10:29
  this is a comment from Sean
• 10:32
  Domagal Goldman who's Director of
• 10:34
  Astrophysics at NASA, uh, who says we were
• 10:37
  all hoping for more science from Swift, but
• 10:39
  we knew the takeaways from this mission would
• 10:41
  be worthwhile either way. We've gained so
• 10:43
  much through the series of accomplishments up
• 10:45
  to this point. Building, testing and
• 10:47
  operating. This mission has already
• 10:49
  strengthened America's space industry
• 10:51
  pipeline, advancing in space
• 10:54
  servicing capabilities in completely new
• 10:56
  ways. And I think that's a reflection of the
• 10:58
  fact that this was all done in double quick
• 11:00
  time. Uh, even though it's in the end not
• 11:03
  succeeded, um, it has been um, a
• 11:06
  mission from which people have learned a lot.
• 11:08
  So just going back to James's question, how
• 11:11
  do you boost uh, the
• 11:14
  orbit or increase the orbit of a spacecraft?
• 11:17
  Uh, what you have to do is you have to
• 11:19
  increase its velocity. And so
• 11:22
  um, what I think the Link
• 11:24
  spacecraft would have done would have been
• 11:27
  and I think it had three arms that could
• 11:29
  grapple onto Swift ont
• 11:32
  hard points on Swift's sort of
• 11:35
  fuselage, what they call the bus, the main
• 11:36
  part of the satellite. So I think it was
• 11:39
  three that it will grab hold of and then you
• 11:41
  use the link, uh thrusters
• 11:44
  to apply a velocity or
• 11:47
  an acceleration uh, essentially in the
• 11:50
  direction of travel. Uh, because remember,
• 11:52
  all satellites are essentially travelling
• 11:54
  horizontally. They're all moving in
• 11:57
  orbits that are parallel to the Earth. Of
• 12:00
  course, it's the fact that there's a sphere
• 12:01
  that means the orbit is a circ. Um, so what
• 12:04
  you do is you boost its
• 12:06
  velocity. And what that does is
• 12:09
  it raises what we call the apogee.
• 12:13
  So it elongates the ellipse
• 12:15
  that the spacecraft
• 12:18
  orbit is in. Um, so
• 12:21
  you boost its velocity and
• 12:23
  you get an extended ellipse. And the near
• 12:26
  part of the ellipse, what we call perigee,
• 12:28
  the part closest to the earth, sort of where
• 12:31
  you started from, that's still at the same
• 12:32
  height, but you've given the far part,
• 12:35
  um, the apogee a much higher
• 12:38
  radius. And then what you do is,
• 12:41
  uh, at the apogee, you
• 12:44
  boost it again, you boost the velocity again.
• 12:46
  And that lifts the perigee, that actually
• 12:49
  lifts the near point. So it's a two step
• 12:51
  process. Uh, but it's all about just
• 12:53
  increasing the velocity of the spacecraft.
• 12:55
  And that automatically lifts the orbit,
• 12:58
  uh, in a way that I've described.
• 13:00
  Andrew Dunkley: That's how it works in theory, James. It
• 13:03
  unfortunately didn't happen. The rescue
• 13:05
  missions failed. But uh, the good news news
• 13:08
  is Swift will continue to operate. Uh,
• 13:10
  they've restarted um, its observations,
• 13:14
  uh, but it is in a very rapid
• 13:17
  decaying orbit. And they expect re
• 13:20
  entry late, uh, well, not so long
• 13:23
  now. Late this year.
• 13:25
  Andrew Dunkley: Late.
• 13:26
  Andrew Dunkley: We're entering late this year already. So we
• 13:29
  are.
• 13:29
  Professor Fred Watson: That's right. Yeah. I don't think it's much
• 13:31
  longer.
• 13:31
  Andrew Dunkley: I only got a couple of months to live.
• 13:33
  Unfortunately they couldn't save it. But um,
• 13:35
  yeah, I
• 13:38
  guess they were very hopeful. But um,
• 13:41
  it was a pretty last minute thing to try and
• 13:44
  do and um, it just didn't work out,
• 13:47
  unfortunately. Got um, a
• 13:50
  message from Europe as well. Someone's up at
• 13:52
  4am and I asked why and he said my little
• 13:54
  toddler woke me up. They do that.
• 13:57
  They do that. But um, anyway, glad you found
• 14:00
  us. Uh, thank you James for the question.
• 14:03
  Uh, we'll move straight onto our next
• 14:05
  question from Dale, who's in New Zealand.
• 14:08
  Uh, he's referring to a question that came
• 14:10
  from Roger the trucker, which uh, I think we
• 14:12
  covered a few weeks ago. Um, who asked?
• 14:15
  Is distant light redshifted? What happens
• 14:18
  to the lost energy? And Dale says
• 14:21
  surely no energy is lost. Isn't it just
• 14:24
  stretched?
• 14:27
  Professor Fred Watson: Yes, that's right. So, excuse me, but
• 14:30
  longer wavelength, which is what you stretch
• 14:32
  it into, um, means,
• 14:36
  um, means that the energy that's
• 14:39
  carried is less. Uh, and
• 14:42
  I guess it's like, you know,
• 14:45
  the particle wave duality. The
• 14:48
  fact that we can think of light as both a
• 14:50
  particle and as a wave. You can think of it
• 14:53
  as a particle with certain energy, a photon,
• 14:55
  uh, or you can think of it as a wave with a
• 14:57
  certain wavelength. And the longer the
• 14:59
  wavelength, the lower the energy. So we talk
• 15:01
  about high energy astrophysics as being
• 15:04
  things that. Where we use gamma rays and X
• 15:06
  rays to. To probe space.
• 15:09
  So, um, I do remember we
• 15:12
  looked at this question and got a number of
• 15:15
  different answers. Um, most of
• 15:18
  which were don't worry about it.
• 15:22
  Which is kind of, uh, what our listener
• 15:25
  is, uh, saying, don't worry about it.
• 15:28
  It'll be all right. Um,
• 15:32
  there is a suggestion that some of that
• 15:34
  energy, uh, effectively goes
• 15:37
  into raising the background temperature of
• 15:38
  the universe. By a tiny gazillionth of
• 15:41
  a degree. Uh, but there's another point of
• 15:44
  view. It's interesting. It's worth, um, you
• 15:46
  know, having a look and, uh. Going down the
• 15:48
  rabbit hole. I, uh, haven't had time to do
• 15:50
  that again. Um, but, um.
• 15:53
  Uh, yeah, go down the rabbit hole and have a
• 15:55
  look at what people think about the energy
• 15:57
  loss, uh, from, um. The redshift
• 16:00
  energy is lost. It goes somewhere, uh,
• 16:02
  because the universe is a closed system. Uh,
• 16:05
  um. My understanding, as it was always. That
• 16:08
  it basically heats the cosmic microwave
• 16:09
  background very, very slightly.
• 16:12
  Andrew Dunkley: That makes sense, yes. Hope that answers your
• 16:14
  question, Dale. Thanks for sending it in and
• 16:16
  hope all is well in New Zealand.
• 16:18
  This is space nuts. Andrew Dunkley here on a
• 16:21
  Q and A edition with Professor Fred Watson
• 16:23
  Watson.
• 16:26
  Okay, Houston, we've had a problem here.
• 16:28
  Generic: This is Houston.
• 16:28
  Andrew Dunkley: Say again, please. Houston, we've had about.
• 16:30
  We've had a main B plus undervolt. Roger,
• 16:32
  main B undervolt. Okay, standby 13. We're
• 16:35
  looking at it, Stacey, but I'm going to let a
• 16:37
  cat out of a bag here, Fred Watson. In my,
• 16:39
  um, new trilogy that. It's just
• 16:42
  been released and I think I've sold one copy.
• 16:45
  Um, the main B bus
• 16:48
  undervolt problem on Apollo 13.
• 16:50
  Professor Fred Watson: All right.
• 16:51
  Andrew Dunkley: I used that in. I used that in one of the
• 16:53
  books just for fun.
• 16:56
  Professor Fred Watson: Love it.
• 16:57
  Andrew Dunkley: Yeah.
• 16:58
  Professor Fred Watson: Anyway, it's nice to put these little, little
• 17:00
  snippets in. I've done that in a few of my
• 17:02
  books that put things in it that probably I'm
• 17:05
  the only person would know that I was
• 17:07
  alluding something else.
• 17:08
  Andrew Dunkley: I do it a lot. I think I've done it a few
• 17:11
  times in this series. Just for fun. And the
• 17:13
  people who know will know. The people who
• 17:15
  don't will just keep reading and it'll just
• 17:17
  be part of the storey, so. That's right,
• 17:19
  yeah.
• 17:19
  Um, let's go to our next question from one of
• 17:22
  our regular, uh, contributors. Here is Fred.
• 17:25
  Andrew Dunkley: Hello, friend. And Andrew. This is
• 17:28
  Fred calling you from
• 17:30
  Minnesota. Thank you for your podcast.
• 17:33
  I never miss an episode for it. I have
• 17:36
  a question for you about the temperature
• 17:39
  on the moon. Now, it's well
• 17:42
  known that the temperature on the surface
• 17:45
  swings greatly with the orbit of the
• 17:48
  moon. But what about underneath
• 17:51
  the moon as below its surface?
• 17:54
  How constant is it? Does it also
• 17:57
  swing around? Does it matter how deep
• 17:59
  you go underneath the moon?
• 18:03
  This has, of course, relevance
• 18:06
  to putting people on the moon and living
• 18:09
  on them. Thank you very much
• 18:12
  for the question. Bye now.
• 18:14
  Andrew Dunkley: Thank you, Fred. He brings up a really good
• 18:16
  point. We are going to have people spending
• 18:19
  time on the moon in the not too distant
• 18:21
  future and some of them will, you know,
• 18:23
  they're not just going to go up and kick the
• 18:26
  sand and then come home again like you do
• 18:27
  when you go to the beach. They'll be up there
• 18:29
  for a decent period of time. Um,
• 18:32
  I'd say rotating rosters of weeks or
• 18:35
  whatever. Uh, how are they going to deal with
• 18:37
  these temperatures? Because, uh, as far as I
• 18:39
  recall, the moon is one of
• 18:42
  the coldest places in the solar system, is it
• 18:45
  not?
• 18:47
  Professor Fred Watson: And the warmest as well. Um, it's
• 18:49
  temperature variation. I always get these
• 18:51
  figures wrong, but it's almost a 300 degree
• 18:54
  Celsius variation from minus
• 18:56
  150 to plus 150. They're slightly different.
• 18:59
  Andrew Dunkley: Just like Dubbo.
• 19:03
  Professor Fred Watson: Yes, it's a lot like Dubbo.
• 19:06
  Andrew Dunkley: No, I think our temperature variations are
• 19:09
  somewhere around 50 degrees, but it's still.
• 19:12
  Professor Fred Watson: Yeah, that's right. That's remarkable.
• 19:14
  Andrew Dunkley: Celsius.
• 19:14
  Professor Fred Watson: Um, 50. Celsius. Yes.
• 19:17
  What's your lowest that you've ever had?
• 19:20
  Andrew Dunkley: Minus 7.4, I think.
• 19:23
  Which was only a couple of years ago. Yeah,
• 19:25
  yep, something like that.
• 19:29
  Quite. Our warmest is 40.
• 19:32
  No, we got to 50 the year before last.
• 19:36
  So, uh, there you go, it's 50. 50. Nearly 58
• 19:38
  degrees variation.
• 19:41
  Professor Fred Watson: Yeah, yeah. Eat your heart out, Moon.
• 19:44
  Because the moon's much higher. And
• 19:47
  of course the reason for that is that there's
• 19:49
  no atmosphere. So during the day you've got
• 19:52
  the sun's radiation beaming down, heating the
• 19:55
  surface. And, uh, it's the surf temperature
• 19:57
  that we talk about when we mean these things.
• 19:59
  Well over 100 degrees and at night that just
• 20:02
  all radiates into space, um, and
• 20:05
  the surface cools to minus 100
• 20:08
  and something degrees as well. I can't
• 20:10
  remember that. I can never remember the exact
• 20:11
  figures. I should have them in my head. But
• 20:14
  the good news is, and I think, you know, this
• 20:16
  is what Fred's alluding to is that
• 20:20
  the, the lunar soil
• 20:23
  um, is very poor. It's a very poor
• 20:26
  conductor of heat. Ah, and
• 20:29
  so that means that, you know, you don't have
• 20:32
  to go down
• 20:35
  too far to find that those temperatures
• 20:38
  even out quite a bit. I'm reading
• 20:41
  from um, from a, um, an article
• 20:44
  actually on lunar surface temperature. Uh,
• 20:46
  I'm going to quote from it. Measurements from
• 20:50
  the Apollo 15 and 17
• 20:52
  missions show that temperatures
• 20:55
  35 centimetres below the surface, that's ah,
• 20:58
  not much more than a foot, are ah, 40 to
• 21:01
  45 degrees Kelvin,
• 21:03
  warmer than the minimum
• 21:06
  surface nighttime temperature, avoiding the
• 21:09
  harshest cold. So it brings the
• 21:11
  temperature up and that's only a foot or so
• 21:14
  below the surface. And then continuing the
• 21:17
  same article, um, by the time you
• 21:19
  get to getting on for a metre, 80
• 21:22
  centimetres, 30 inches if you prefer
• 21:25
  that below the surface the
• 21:29
  day and night variations are
• 21:32
  uh, imperceptible. So that
• 21:35
  is incredible really that you've only
• 21:37
  got to go um, you know,
• 21:40
  80 centimetres less than a metre below the
• 21:43
  surface and the material there
• 21:46
  does not see these enormous
• 21:48
  swings in temperature. Uh, it's become
• 21:51
  imperceptible. Um, and then
• 21:54
  when you get to below a metre, um,
• 21:58
  then you get an average temperature which is
• 22:01
  kind of the average of the hottest and the
• 22:02
  coldest. And that is very nice because it
• 22:05
  makes it about 20 degrees Celsius
• 22:07
  or um, you know,
• 22:10
  that sort of basically that uh,
• 22:14
  20 degrees Celsius is.
• 22:17
  I beg your pardon, it's minus 20 degrees
• 22:19
  Celsius, not 20 degrees but still
• 22:22
  within reason. Um, and so
• 22:26
  it means that if you can look for caves
• 22:29
  and pits in the lunar, uh,
• 22:32
  regolith in the lunar soil then
• 22:35
  you've got a really good chance of having a
• 22:38
  place where you've got, without any air
• 22:41
  conditioning or anything. You've got a
• 22:43
  ready temperature round about 17
• 22:46
  degrees Celsius, uh, day and night
• 22:49
  without these extremes. So um, that's
• 22:52
  really good news. I think from the
• 22:55
  perspective of our future exploration of the
• 22:57
  moon, uh, that this variation uh,
• 23:01
  is only on the surface. The extreme
• 23:04
  variation is only on the surface itself.
• 23:06
  Andrew Dunkley: M There you go Fred. So good question, thanks
• 23:09
  for asking it. Uh, and uh, great to hear from
• 23:12
  you again.
• 23:13
  Uh, our European listener whose
• 23:15
  toddler woke them up at 4am has sent us a
• 23:18
  note Saying he's an astrobiologist working in
• 23:21
  the ExoMars science team. Uh,
• 23:24
  he's a big fan of the show and I thought,
• 23:26
  oh, I'm going to look this up. ExoMars, uh,
• 23:29
  science team, uh, is um,
• 23:32
  looking into ExoMars, uh, missions,
• 23:38
  uh, particularly in um,
• 23:41
  part, uh, working on the uh, Roslyn Franklin
• 23:44
  rover. And they're trying to find out
• 23:47
  did Mars ever have life and could traces of
• 23:49
  it still be preserved underground. So um, I
• 23:52
  looked that up and since then another note's
• 23:55
  come through. Our Rover has a 2 metre drill
• 23:58
  to get samples from Mars. Uh, subsurface
• 24:00
  organics will be preserved. Um,
• 24:03
  what do you think will we find? And
• 24:05
  biosignatures, always throwing you a
• 24:08
  curvy there.
• 24:10
  Professor Fred Watson: The trouble is it's knowing that they are
• 24:12
  biosignatures. Yes, he or she, uh.
• 24:15
  Well, look, an honour to have somebody uh,
• 24:18
  working right in the front line of this
• 24:20
  stuff, particularly in Europe, very close to
• 24:23
  my heart. Uh, it's an honour to have you
• 24:25
  listening and um, participating in the show.
• 24:28
  Thank you very much. Um,
• 24:31
  the issue with biosignatures is are
• 24:33
  they biosignatures or are there false alarms?
• 24:36
  And it is so difficult
• 24:39
  to essentially eliminate everything
• 24:42
  else that could be causing whatever that
• 24:45
  biosignature is, whether it's uh,
• 24:47
  microbial structure or uh,
• 24:50
  metabolic activity or whatever it is. It's
• 24:53
  very hard to eliminate what you might call
• 24:56
  natural, non biological, uh, origins.
• 24:59
  But digging deep is the way to go. Uh,
• 25:02
  I think the ExoMars project has
• 25:05
  had mixed fortunes because it was originally
• 25:09
  uh, going to be uh, a joint
• 25:11
  European Russian project, um,
• 25:14
  which I think was shelved probably at the
• 25:16
  time of the invasion of Crimea in
• 25:19
  2014. I think that's what happened. Um,
• 25:22
  and so, um, But I think Europe
• 25:25
  is carrying on its own,
• 25:28
  uh, I wish, uh, uh, our listeners and
• 25:31
  everybody working with them every success,
• 25:33
  uh, because these are things we want to know.
• 25:35
  Andrew Dunkley: Yeah, absolutely. Uh, Issa says the rover
• 25:38
  will target an ancient clay rich region where
• 25:41
  minerals formed in the presence of abundant
• 25:43
  liquid water and could have preserved
• 25:46
  evidence of ancient life. And their launch
• 25:48
  window is set for late
• 25:51
  2028 at this stage. So. Yes,
• 25:54
  fingers crossed. That'll be exciting. Looking
• 25:55
  forward to that. Thanks for letting us know.
• 26:00
  Generic: Roger, in your labs right here.
• 26:01
  Andrew Dunkley: Also space nuts.
• 26:03
  Final question, Fred Watson. This comes from
• 26:05
  Kevin. So, uh, this is uh, going to be more
• 26:08
  of a hypothetical. I understand we have no
• 26:11
  observational evidence of white holes, but we
• 26:13
  do have a fair mathematical understanding of
• 26:16
  them. So my question is if a white hole
• 26:19
  actually existed, what would happen
• 26:22
  if it Merged with a black hole. Would they
• 26:24
  essentially cancel each other out? What
• 26:26
  would, would be left afterwards? Just, uh,
• 26:29
  some random thoughts. I was thinking, uh, and
• 26:31
  would love some insight on what you guys
• 26:34
  think. Amazing show. Keep up the great work,
• 26:36
  Kevin. I know the answer to this one,
• 26:38
  Fred Watson.
• 26:39
  Professor Fred Watson: Good, good. It would
• 26:41
  be a grey hole. Uh, well,
• 26:44
  that's. Could be right. My mind
• 26:47
  went straight to when a black hole and a
• 26:50
  Whitehall love each other very much.
• 26:52
  Andrew Dunkley: Oh, boy.
• 26:53
  Professor Fred Watson: Then they
• 26:56
  come together and make a grey hole. How's
• 26:58
  that? Ah, yeah, um, that's a
• 27:01
  good question. And I, Sorry, I'm,
• 27:04
  I'm still a little bit, um,
• 27:06
  unprepared for these, um,
• 27:09
  because my focus is on making my knee better.
• 27:12
  But, uh, I would like to cheque that out and
• 27:15
  see what the pundits think. In the world of
• 27:17
  black holes and white holes, we've never seen
• 27:19
  any evidence for a white hole. Um, you
• 27:22
  can create a white hole
• 27:25
  mathematically, uh, by reversing the
• 27:28
  time, uh, factor in the equations of
• 27:31
  relativity, and then you get a white hole
• 27:33
  rather than a black hole. But that does not
• 27:35
  mean that they exist. We do know that black
• 27:37
  holes exist. The evidence for their existence
• 27:40
  is absolutely compelling. Um,
• 27:43
  I, you know, the idea of them cancelling out
• 27:46
  is the one that has the most appeal, because
• 27:49
  that sounds feasible. Gravitational wells.
• 27:51
  Yeah. Of different kinds of,
• 27:54
  uh. But I, I, That's a flippant comment. I'll
• 27:57
  need to look at this again. Perhaps you can
• 27:59
  remind me until we can get back to Kevin, uh,
• 28:01
  and talk about what happens when you get a
• 28:04
  grey hole.
• 28:05
  Andrew Dunkley: Yeah. Um, I think you end up
• 28:08
  in a, uh, retirement village.
• 28:09
  Professor Fred Watson: Sure.
• 28:14
  Andrew Dunkley: And Moose says, aren't white holes still
• 28:16
  theory only? Yes, absolutely.
• 28:18
  Professor Fred Watson: That's right. Absolutely right.
• 28:21
  Andrew Dunkley: It's like many things in the universe, the
• 28:22
  mathematics says, yes, they could exist,
• 28:26
  um, but we've never seen them and
• 28:29
  we don't have any other proof, so.
• 28:31
  Professor Fred Watson: Quite fun.
• 28:32
  Andrew Dunkley: Yes, indeed. Uh, thanks for the question,
• 28:35
  Kevin. Thanks to everybody who contributed.
• 28:37
  Thanks to our live audience who contributed
• 28:39
  today. Lovely to hear from you. I think
• 28:41
  that's the most active it's ever been. So
• 28:44
  it's, uh, value added to the show. We really
• 28:46
  appreciate it. And thank you, Fred Watson.
• 28:48
  Professor Fred Watson: Uh, as always, it's a pleasure,
• 28:51
  Andrew. I hope next time we speak my
• 28:54
  knee will be just slightly more tractable
• 28:57
  than it is at the moment as the months wear
• 28:59
  on and I get back to being 100%
• 29:03
  mobile again, which I'm looking forward to.
• 29:05
  Andrew Dunkley: Fingers crossed. Good to have you back too.
• 29:07
  Professor Fred Watson: Thank you.
• 29:08
  Andrew Dunkley: Professor Fred Watson Watson, astronomer at
• 29:10
  large. And don't, uh, forget to visit us
• 29:12
  online where you can leave questions on the
• 29:14
  AMA button at the top. Um, text or audio
• 29:16
  questions. Don't forget to tell us who you
• 29:18
  are or where you're from and please leave
• 29:20
  reviews wherever you listen to us, us. And,
• 29:22
  um, have a look around on our website while
• 29:24
  you're there and see what else you can find
• 29:26
  to, uh, keep you amused between
• 29:29
  episodes. And uh, thanks to Huw in the studio
• 29:31
  who couldn't be with us today because, um,
• 29:34
  like many things in the universe, his
• 29:37
  existence is just theoretical. And from me,
• 29:40
  Andrew Dunkley, thanks for your company.
• 29:42
  We'll see you on the next episode of Space
• 29:43
  Nuts.
• 29:44
  Andrew Dunkley: Bye.
• 29:44
  Generic: Bye.
• 29:46
  Andrew Dunkley: You've been listening to the Space Nuts
• 29:48
  podcast, mission completed. Available at
• 29:51
  Apple Podcasts, Spotify,
• 29:53
  iHeartRadio or your favourite podcast
• 29:56
  player. You can also stream on
• 29:58
  demand@bytes.com this
• 30:00
  Professor Fred Watson: has been another quality podcast production
• 30:02
  from bytes.com.