Professor Fred Watson: Hello again.
Andrew Dunkley: Andrew Dunkley here from Space Nuts, where
we talk astronomy and space science. Good to have your company.
Coming up on this episode, we are, going to talk
about the moon. It's got a near side, it's got a far side,
but we're going to talk about the inside.
it's, discovery of the Grail mission.
which means what we're talking about is a flesh
wound. another Hubble tension. Think about it.
Another Hubble tension theory. And we're talking
evolution this time. And a triple system in the
Kuiper Belt. Belt. So buckle up for this
episode of space nuts.
Voice Over Guy: 15 seconds. Guidance is internal.
10, 9. Ignition
sequence start. Space nuts. 5, 4, 3,
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report it feels good. And back with us
again is Professor Fred Watson Watson, astronomer at
large. Hello, Fred.
Professor Fred Watson: Hello, Andrew. Hello. Took me in couple. Couple of
seconds. But I did get the.
Andrew Dunkley: To get the, flesh. The flesh wound. Flesh wound. The
Grail mission.
Professor Fred Watson: Only a flesh wound.
Andrew Dunkley: It's only a flesh wound.
Professor Fred Watson: That's right. no arms, no legs, but
nothing.
Andrew Dunkley: Flesh wound. so, yes, that I,
I can't help dad jokes and, and, and
I, I. When I do the presentations at golf on
Fridays, which has become my job somehow.
I always have to finish on a dad joke. It's just become a
thing.
Professor Fred Watson: Yes, yes, I'm sure it has.
Andrew Dunkley: The reputation continues to spread. we'll be
talking dad jokes in our next episode,
our Q A episode as well.
we should begin with this,
Grail mission and the findings of the moon's
unusual interior. This might
come as a surprise to some people.
Professor Fred Watson: Well, I think it does. Excuse me. I think it did come
as a surprise when the discovery was made as well. These, are,
scientists from NASA and other institutions, missions.
yeah, let's do the dad joke first. The, It's not Monty
Python and the Holy Grail.
Grail stands for Gravity Recovery and
Interior Laboratory. And it was a mission,
which I guess it was more than. It's probably a
decade ago. it's a very, very
neat piece, of research. And
NASA, you know, the clever stuff that they do is just
unbelievable.
so what do you do if you want to sense the
gravity of, a planet that
you're flying over? You want to map out the gravitational
details. And by doing that, you can
work out what's underneath the surface. because
that's usually what affects the gravity above
the surface of a planet. And I'm Talking
now about really minor,
disorder, differences and discrepancies
in gravity, how the Grail mission
worked. and I'm kind of casting my memory back now.
two spacecraft, in orbit around the
Moon, separate in the same. They're both in
the same orbit. They were separated, I think,
by about 200 kilometres, one in front of the
other. But the
distance between them could be detected
by microwave transmission
to well under a millimetre. I can't remember what
it was. It was a few microns, I think. But
this tiny, tiny difference between the
position of the two spacecraft, you can measure it,
by these microwave signals. And so as the two
spacecraft go around the moon, their
separation changes slightly as a result of the
gravitational force, gravitational pull of the
terrain beneath them. and it actually
is a, really very sensitive
way. I love the fact that they
rediscovered, something that we talked about in
the very earliest, history of moon exploration.
Back in the, Gemini and Apollo era, back in the
19, 60s, mass, cons,
which were mass concentrations, concentrations
of mass that were unexpected underneath the Moon's surface. They
were actually measured just by spacecraft that were
orbiting. Single spacecraft orbiting the
Moon. but, GRAIL actually mapped them out in much
more detail. We know a lot more about these mascons now than we did
before. But what has happened,
and by the way, I should just mention one, I should have
put this in as a, As a quirky factoid, shouldn't I?
Flippant factoid that the two,
spacecraft, the two components of Grail. Do you remember what they were
called?
Andrew Dunkley: Oh, no.
Professor Fred Watson: Ebb and flow. And it came.
I think it was school kids who did that. If I remember rightly,
NASA sent out a competition saying, we've got two spacecraft in
orbit around the Moon. What do you want to call them? And they were called ebb and
flow, which is very, very nice
indeed. Anyway, ebb and flow, in
combination, measured, virtually the
gravitational map of the whole Moon. But
what has come to light
is something a little bit more subtle.
these, researchers who've now used these
NASA data to deduce that
There's a, 2 to 3%
difference in the
ability of the lunar mantle. Now, that's
the layer below the crust. That's the
layer that surrounds the core of the Moon. The
ability of the mantle to
deform. So what you're
saying is there's a difference in sort of
flexibility from one side of the Moon to the other.
And remember, as we know The Moon always faces the
same side to Earth. and so that's, you know, there's
a different gravitational pull on one side from what there is on the
other. but what they've interpreted this difference
as being, they say it's
symptomatic. The fact that there's this difference in
the Moon's mantles ability
to deform, to change its shape.
they say that is best explained
by the temperature inside
the mantle on the near side
being as much as 170 degrees
Celsius hotter than what it is on
the other side. Wow, that's a side facing us. Yeah, it
is. It's not a small amount, it's not a few degrees, it's a lot.
and it's enough to change the viscosity of the mantle,
how flexible it is. and so
that's the new finding that's come from
ebb and flow. And I think what they're saying is that
the spacecraft was in orbit for long enough that it
could detect differences in the
gravitational pull as it flew over the same part of
the Moon more than once. It could see a difference in the
gravitational pull from one trip to another. So there's a
time dependent thing on it, and that's how they know
about the Moon's ability to deform. I'm
actually, interpreting that in my own way.
There's a nice paper in Nature
magazine, perhaps one of the two leading
journals for science in the world, which has the title of
thermal asymmetry in the Moon's mantle
inferred from monthly tidal response.
Andrew Dunkley: Okay, so my question
straight up is, could that explain,
or does that explain why the near side
and the far side of the Moon are so
very different? when you're talking topography,
yeah, I.
Professor Fred Watson: Think it's the other way around. I suspect the difference in
topography is, what
causes the difference. Although they're probably all
mishmashed up,
into the same sort of thing.
But the Moon's nearside,
I think probably the way you've put it, actually Andrew,
is probably more correct. The Moon's nearside,
has had much more volcanic activity
than the far side. This is between 3 and 4 billion
years ago. It was highly volcanically active, which is why we've
got all these lava flows on the near side, which we see as
the maria, the grey patches on the Moon.
but the details of what
these researchers think, contributes
to the difference, in temperature,
they suggest I might actually, I think this is
Nature's press release So I might just read
straight from it.
they hypothesise that this thermal
difference could be sustained by radioactive
decay of thorium and titanium within the moon's
near side, which could be a remnant of
the volcanic activity that formed the near side surface
3 to 4 billion years ago.
Andrew Dunkley: That is really interesting. Yeah,
I'm fascinated
by a couple of things, that we're using old data to make new
discoveries. We've talked about that in other
studies that have more papers that have been released in
recent years. also the fact that there's
effects on the moon that we see in
other parts of the solar system, with, with
variations in the way the moons
interact with their host planet for example. I
suppose.
Professor Fred Watson: Yes.
Andrew Dunkley: It's a similar situation is it not?
Professor Fred Watson: Yes, that's right. So you've got and in fact most of these
moons around, certainly the giant planets are ah,
which is where most of the moons in the solar system are.
there's only three in the inner solar system. Ours and
Mars is two little satellites. But
places like Enceladus, Ganymede, perhaps
Callisto, Europa, around Jupiter, perhaps
Titan as well, they,
they could do use
this technology to
actually interpret what's going on
inside these worlds without having to land
a spacecraft on the surface. That's the,
the great thing because putting something into orbit around
Enceladus for example, would be much
more straightforward, much less energy
hungry than putting a spacecraft down onto
the surface where you've got all the risks of
collisions and tipping over like several
of the lunar probes have done, they've fallen over.
all of that is the hazard when you're
landing something on the surface. So yeah, I think
it's got a future. Now. you can,
as I kind of mentioned earlier, you can do some of this
kind of work with a single spacecraft, but if
you can launch two with this microwave,
microwave bridge between them, then you can do much, much
more as the Grail spacecraft
demonstrated.
Andrew Dunkley: Okay, so yeah, the moon is not as
it seems, at least not on the inside.
Professor Fred Watson: Well no, that's right. Or maybe, maybe it is
as it seems because the two sides are so different
when you look at them. As you said, the topography
is quite different from one side to the other.
Andrew Dunkley: It's a great story. If you'd like to read up on that, you
can find, you can go find the paper if you can remember the title of
it because it's got more than three words in it. So I'm stuffed.
But yeah, DailyGalaxy.com is
the website. DailyGalaxy.com
this is space Nuts with Andrew Dunkley and Professor
Fred Watson Watson.
Three, two, one.
Professor Fred Watson: Space Nuts.
Andrew Dunkley: Fred Watson, I neglected to mention my office
background at the beginning. if I just put my thumb
over the camera, people on YouTube will see
a massive mountain there. That's the Fugo
volcano in Guatemala. I took that photo on the
7th of April. And Judy and I
have a history of visiting volcanoes, getting home and then finding
out they started erupting. And that's exactly what's happened with
Fugo. So if you're on YouTube and you're watching us, when
we're finished, go and have a look at some of the eruption
footage from the Fugo volcano in Guatemala at
the moment. It is spectacular. We had to drive
between three volcanoes to get
to the township of Antigua and
you could see these things for miles. I mean
they're strata volcanoes, they are absolutely
enormous. They're around 12,
13,000ft at the peak above sea level.
and they are spectacular. And we
literally had to drive between two of them to get to the
town. That one was on our left and the
agua volcano was on our right. and
the town is in the foothills of the the two nearest
volcanoes. And it's just an awe
inspiring sight. But I just thought it was funny that
well maybe not funny haha, but funny that we went to
Hawaii, got home and Kilauea
erupted. Happens a lot. I went to
Vanuatu, Matt Yasser, got home, it
erupted and stopped air traffic for a couple of weeks. And
now this one's erupting a month after we were there.
So we're not going to be invited back I don't think.
But Fugo's got a history though it
erupts quite often. But I just thought people would be interested
to see a photo of it. as you know, I'm a
volcano junkie.
Professor Fred Watson: So when we were in Iceland earlier in the year, the
Reykjanes peninsula had just
erupted as well. Well here there was a
lot of steam coming up from from the, you know, the fishes in the
ground.
Andrew Dunkley: Yeah. In the next few months we'll be visiting
the Canary Islands.
Professor Fred Watson: Sure.
Andrew Dunkley: Yeah. So that one's got an active volcano
and we're visiting Iceland as well.
yeah. Could, could have some stories to tell.
Professor Fred Watson: Yeah.
Andrew Dunkley: Ah, good. Okay Fred Watson, let's move on
to our next story.
And this one is about yet again,
the Hubble tension, the, the
quirk of space that we
can't quite get our heads around. We can't solve the
differentials or the problems. Many are saying, look,
it's natural. But Now
another Hubble Tension theory, gee that's
hard to say. is making its way
into various papers. one in particular I
suspect, because now they're talking about
evolution in dark matter.
This sounds like pie in the sky
type stuff but we've got to, we've got to come up with
answers. The only way it is to publish papers with
theories and you know,
toss it around.
Professor Fred Watson: Indeed.
Andrew Dunkley: That's like, like a salad. A space
salad.
Professor Fred Watson: yeah, I've just I'm m hesitating because I've just seen who one of the
authors of this paper is.
it's a scientist who's known for
provocative papers. Avi
Loeb, and he's at Harvard, Smithsonian,
Centre for Astrophysics. So the
paper that we're talking about is called Evolving Dark Energy
or Evolving Dark Matter.
and this is really esoteric
stuff, Andrew. Always when we're talking about this
stuff we're just glossing over
a lot of really detailed
science that goes into
realms that even I struggle with. And I'm not
actually a cosmologist, which is why. But
I'm supposed to know my way around some of these topics
better than perhaps the person in the street is.
and this
comes down to something called the equation of states which you and I
haven't talked about. But the equation of state
is a parameter in the universe.
It's a parameter generally. It comes from thermodynamics,
which essentially characterises,
as the name almost implies, it
characterises the overall behaviour of the
universe. The equation of states, okay, Symbolised
by the, the character W.
so the, the work that's
being reported here. and as I've said
it's on a, on a, there's a, there's a.
Basically a preprint as we used
to call them. this is a paper that's not yet been
refereed which is
going to go into. I can't see
what journal it's aiming for but it
is called
essentially the title of the paper Evolving Dark Energy
or Evolving Dark Matter. I'm going to read you the
abstract, okay? because that
kind of tells the story even if you don't
know what the details are. We
show that the latest empirical
constraints on cosmology, and by that they mean
measured, from a Combination of desi, that's
the Dark Energy Survey instrument cmb,
that's the cosmic microwave background and supernova
data, that's exploding stars. They've taken
all this data together. The empirical
constraints on cosmology from that combination can
be accounted for. If a small
component of dark matter
has an evolving and oscillating
equation of state within the range minus
1 is greater than less than w, which is
less than 1, that's the range minus 1 to 1 is
somewhere where this equation of state parameter, W
lies. From a fundamental physics perspective,
this interpretation is more appealing
than an evolving phantom dark energy with
W less than minus 1, which
violates the null energy condition.
So in a sense this paper
is kind of in response to
what we're seeing from the latest data actually from
desi, the Dark Energy Survey,
which suggests that dark
energy is getting less.
Or at least what it suggests is the acceleration of
the universe's expansion is getting less.
In other words, the expansion which we know is accelerating
because that's been well measured. But the suggestion
is that that acceleration is slowing
down, so as time goes on it will be
accelerating at a lower rate. What
they're saying is, when you look at the
sort of theory that doesn't make sense, but it makes
more sense if something is going
on with dark matter, that
dark matter, is itself
evolving. Now that
suggests, and they apparently explore this in the
paper, I haven't read the paper, but they explore this,
that suggests that dark matter is something
different from what we think it is because we
imagine dark matter as being some
subatomic particle, which is as yet
unknown, which does not interact with normal matter at
all, which is why we can't see it, and all
it reveals itself by is its gravity.
That's the parameters that we understand dark matter to
be. But what they're suggesting
is that this is something even more
exotic than we have been imagining,
because its parameters
change, its phenomena change and
that leads to a changed equation of state,
the W parameter.
And they actually suggest,
that actually there's some sort of oscillation going
on in it as well. Not just dark matter.
There's a very nice article on physics
phys.org by Brian
Koberlein. I'm going to read a paragraph
for it.
in fact I'm going to read a couple,
let me just read from this because I think that's going to explain
it better than me waffling on.
In work published on the Arxivist print server, the
Authors look at both evolving dark energy and evolving
dark matter and argue that the latter is a
much better fit to the observational data. The first thing they know
is that the two models are somewhat related. Since the
evolution of the cosmos depends in part on
the ratio of dark energy to matter density,
a model with constant dark matter, which is what we have at
the moment, and evolving dark energy,
will always appear similar to a model with
evolving dark matter and a constant dark energy.
That's a good point. They then go on to explore the idea of
some kind of exotic dark matter, one that has a changeable
equation of state to match observation. The dark
matter equation of state must oscillate
in time. This isn't an outlandish
notion. I think they're trying to convince
us here in space.org
neutrinos have mass and don't interact
strongly with light. While they can't account for all the dark matter
in the universe, they are a form of hot dark matter.
And neutrinos undergo, mass oscillation.
Perhaps cold and dark matter particles undergo,
Sorry. Perhaps cold dark matter particles undergo
a similar oscillatory, effect.
The authors find that the best fit to
observational data is a universe where about
15% of the cold dark matter is oscillatory,
and the remaining 85% is
standard dark matter. This would allow for
the Hubble tension to be covered while
still matching the dark matter observations we
have. And I love the last paragraph.
Andrew Dunkley: Yeah, I do too. I was just reading it.
Professor Fred Watson: It should be stressed that this work presents
a toy model. As the authors themselves note, the
work is a broad concept that does not pin down specific
constraints for dark matter particles. But the work does open the door to
a broader range of dark matter models. At this point,
evolving dark matter is worth considering. Well, I agree with that.
I think everything's worth calling.
Andrew Dunkley: I was going to ask you where you stand on this and if
it's worth considering, then obviously it is. But
it just adds another potential
explanation of something we know very little
about and.
Professor Fred Watson: Yep. And we worry about a lot, especially
on space. Nuts.
Andrew Dunkley: Yes, yes. And we get a lot of questions about it. And
so a lot of people thinking about this stuff,
if it's, if it's in fact stuff.
Professor Fred Watson: Yes, well, yes, that's right. It could be something other than
stuff.
Andrew Dunkley: Yes, yes. So, yeah, it's a
really interesting idea and, well, I
suppose, it'll get tossed around and people will come up with other
explanations. But the thing is, a paper
like this, even if it's wrong may
spawn a level of thinking that might send us down
a path where we might eventually figure it out. I mean that's another
possibility.
Professor Fred Watson: that's, that's true. That's correct.
and that's the way science works as well. Exactly as you've
said.
Yes, indeed.
Andrew Dunkley: All right. as Fred Watson said, you can read
all about it@the phys.org website. That's
P-Y-S.org or you can
read the published paper on the archive reprint
server if you like. This is Space Nuts. Andrew
Dunkley here, Fred Watson Watson there.
Okay, we checked all four systems.
Our final topic today, Fred Watson,
is a really interesting one and it
is going to take us to the Kuiper
Belt.
So tighten up your buckle and get ready for
this one because we think there has
been discovered a triple system in the Kuiper
Belt. Now when we talk about the Kuiper
Belt we don't really, we've only been there a
couple of times. fairly recent missions in the last
decade or so. But we've only had close
up observations of two objects in the
Kuiper Belt. So
this discovery was actually made not by
either of those probes but, or the
probe in question. it was made from
Earth, am I correct?
Professor Fred Watson: Yes, that's right. using the Hubble
Space Telescope.
Andrew Dunkley: Yeah.
Professor Fred Watson: Which is you know, still going strong
and still a
fantastic resource
given that it's now 35 years
in space. Yes, it is amazing. That's
right. so, and again this is a team
of researchers from NASA. what they've been doing is
looking through ah, Hubble telescope data
at this very distant object
which is it's a, an asteroid. So it's got a number
148780 and
it's known as Algeria. that's its name.
and they, they,
they haven't seen the three
bodies that they now think make it up, but they've seen
two.
Andrew Dunkley: Wait, dad, joke coming.
Professor Fred Watson: Oh good. Okay. They're seeing two of them.
Andrew Dunkley: I was going so they haven't seen the three bodies. That's a problem.
Professor Fred Watson: Oh, there we go. Love it. Love
it. I
don't understand. You must rehearse our conversations weeks in
advance, Andrew, to get.
Andrew Dunkley: No, the scary part is this
garbage just pops in there
at random moments. It used to happen
when I was on the radio. I'd just be talking about something
and a little voice ago, hey, tell this joke.
Professor Fred Watson: Yeah. And then at the end of it you think I got a Wish
I hadn't said that. Yes, yeah.
Andrew Dunkley: Ah, yeah, yeah.
Professor Fred Watson: Anyway, so it's, it,
it basically is new, ah, research.
And so, so they can see two. They can
detect that there are two objects
orbiting one another.
Andrew Dunkley: I sent the but.
Professor Fred Watson: The butt is. Yes, yes. the
but is that it looks as though one of them is actually
a pair of objects. That's the trick.
So we've got two things that have been
seen, but one of them is
probably a double. And they've had to
use the very detailed,
measurements of the way
the object that they can see orbits the other
one, the way that orbit changes.
that is what tells you that the
central object, if I can put it that way, might actually
be two. and so it's the
outer object, its orbit changes
over time. And it's that change,
that allows the deduction that the central
object, if I put it that way, is.
Well, they say it's either extremely
elongated or it's two separate objects.
And that, you know, the odds are that it is actually
probably two. often though, we've
got this situation, especially with these
distant, asteroids, where you
have clearly something that has been
a binary, two objects in orbit around one another,
but they've gradually, collapsed together,
not in a violent way, and wound up in
contact, which is something we call, believe it or not, a
contact binary. And Arrokoth, it's one
of the Kuiper Belt objects that you actually
just referred to. It's beyond the orbit of Pluto. It was
visited by New Horizons. when we saw it, it looked like
a snowman. And that was very seasonal because I think it was
Christmas time, when it was discovered. But
the analysis of, New Horizons data as it
flew past Arrokoth showed that it wasn't actually
two balls joined together. It was two pancakes joined together,
rim to rim, so that it actually looked like a snowman,
but from the edge on, it looked a lot more like two pancakes
stuck together. But that's a common
phenomenon. Two objects, whatever their shape, is coming
together gently and actually,
basically cementing themselves together just by gravity. But
then the sort of gap between them fills in and you end
up with something that looks like a peanut. So
I think it's still possible that
Algeria could have that sort of
shape. But they actually say,
the research team who's done this, they say that
the triple system actually fits the data
best. it fits it better
than a contact binary or a really elongated
central object. So a triple system is what we
Believe it is, it's a very nice target for
a future mission to the outer solar system, but
that's not going to happen anytime soon. but, yeah,
so, very nice discovery. Triple systems are rare.
That's why, that's why it, you know, it's making the
headlines. These are rare phenomena.
Binaries are very common. In fact, probably most
objects out there in this outer solar system might be
binaries, but triple systems are rare.
Andrew Dunkley: interestingly, this, rock, if you want to call it that,
or system Algeria, is
much, much bigger than Arrokoth. it's, about
124 miles wide, or 200
kilometres. That's a big chunk.
Professor Fred Watson: Yes, it is, yes. A lot, more substantial than
Arrokoth, which was only, if I remember right, it was less than a kilometre, I
think. it's amazing that they found it at all. To
give New Horizons a target beyond, Pluto.
Andrew Dunkley: Yeah, yeah, as you say, we're probably not going to go
back out there in a hurry. These missions are very
long winded because of the distances
involved. We're talking what,
30 or 30 AU or something?
Professor Fred Watson: Yeah, I think this is more, I think it's more like 45 AU or
something like that. So it's. Yeah, AU is an
astronomical unit, 150 million
kilometres.
Andrew Dunkley: Yeah, that's a long way away. but
yeah, it's probably an area of our
solar system, even though it's so remote, that we need to learn more
about because, you know,
some of these rocks get bumped and end up heading our way.
Professor Fred Watson: yes, that's right, they do, or, you know,
gravitationally interact with other objects. but you're right,
in some ways it's the last frontier. It's completing
the evidence for the way we think. Our
solar system formed by this icy,
dust and gas cloud that collapsed. And a
lot of this stuff is the last vestiges, the
outer, the outer vestiges of those,
you know, those, objects that eventually went up to
make the inner planets. These are, these are worlds that have never been
heated. And that's the, you know, the planets have
been, they've been bombarded by gravitational
interactions by collisions and, impacts
and things of that sort, so that they're hot. these worlds
have always been cold and that's why they're so
interesting, because they're sort of the fossil of the solar
system's earliest history.
Andrew Dunkley: Yeah. Yeah.
Well, I guess the time will come where we do extensive studies, but,
I think we'll have to get better spacecraft and
maybe use those, superhighways you were talking
about.
Professor Fred Watson: Yeah, yeah, that's right.
Andrew Dunkley: Get out there and have a look.
Professor Fred Watson: Yes.
Andrew Dunkley: if you'd like to read up on that, you can do that at the
NASA science website or you can go, to the
study itself, which was published in the Planetary
Science Journal. that brings us
to the end. Fred, thank you so much.
Professor Fred Watson: it's a pleasure, Andrew. a nice surprise to see you and, always
a pleasure to talk.
Andrew Dunkley: Good to see you too. And we'll catch you on the very
next episode. Don't forget to visit us online. In the meantime,
we've got, plenty of platforms. We're on Instagram, we're
on YouTube, we're on Facebook, we're on
our own website, spacenutspodcast.com
SpaceNuts IO Either URL will
take you to the same place and have a look around while
you're there. And, Huw in the studio, he
did actually turn up briefly today, but he
forgot to put on his kuiper belt and his pants fell down,
so he had to make a run for it from
me, Andrew Dunkley. Oh, it's terrible. Thanks, for your
company. We'll see you on the next episode of Space Nuts.
Professor Fred Watson: Bye. Bye.
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