Moon Mysteries, Hubble Tension & the Kuiper Belt's Triple Surprise

Kuiper Belt. Belt. So buckle up for this episode of space nuts.

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. 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? 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. 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.

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. 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. 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. 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.

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. Yeah. In the next few months we'll be visiting the Canary Islands. Professor Fred Watson: Sure. 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. 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. 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. 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. 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. 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.

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.

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. 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. Wait, dad, joke coming. Professor Fred Watson: Oh good. Okay. They're seeing two of them. 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. 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. 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.

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. 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. 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.

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. 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. Get out there and have a look.

Professor Fred Watson: Yes. 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. 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.