The Burning Mountains of Io, Part 3

and the most volcanic body in our Solar system. Years ago, we did a multi part series on the moons of Jupiter at large, but this time we wanted to come back and do a deeper focus on Io, in particular to explore its own peculiar Hadian prodigies, because it really is, as I've said in the previous two parts, I think, probably one of the most dramatic places in our Solar system, certainly beyond Earth. Now, if you haven't heard the previous two parts yet, I would recommend you go back and

listen listen to those in order. But to briefly recap, we started off by talking in detail about some really eerie and thrilling images of the surface of Io, mostly based on data collected in twenty twenty three and twenty

twenty four by NASA's Juno mission. These images highlighted a lot of the really enigmatic features of the Moon's topography, including these gargantuan thorn like mountains and volcanic highlands, huge fields blanketed and yellow sulfurous frost, Vast lakes of molten lava constantly overturning with waves, giant lava flows spreading in some cases hundreds of kilometers, forever resurfacing the Moon and

erasing all the scars of its history. We also talked about the physical ironies of the conditions on Io, including the fact that it is at once deep cold due to its extremely thin sulfur dioxide atmospheres inability to trap heat, doesn't really have much of an atmosphere, can't trap heat there of course, in places it is unimaginably hot, due of course, two volcanic eruptions, according to a volcanologist we discussed in Part one, a single one of the Moon's volcanoes,

the lava lake known as Loki Ptera, which we did do a little focus on. That was the one that has a big island in the middle of it actually has a number of islands, but one big old island in the middle which shall not be named. That one volcano emits more heat than all of Earth's volcanoes combined, which is a pretty startling fact. We also talked in previous parts a bit very briefly about the historical exploration of Io, including Carl Sagan's account of the discoveries made

by the Voyager one probe in nineteen seventy nine. We talked about the character from Greek myth that provides Io its name, about how the story of Io was told by Avid and other ancient authors, and how in ancient times the character of Io was said to overlap or interact with other religious figures, such as the Egyptian goddess Isis. In Part two, we discussed when and how Io tends

to pop up in science fiction storytelling. There's sometimes what at least feels like a dearth of Io stories, and then we talked about a mystery regarding images of so called ridges on the Moon's surface, which paradoxically look extremely similar to wind driven sand dunes on Earth and Mars. This is paradoxical because of the tenuous, barely there atmosphere of Io, which wouldn't seem to be thick enough to

support the winds needed to make dunes. And then we got into a paper that offered a likely solution to

this mystery. Finally, in the last episode, we talked about the possibility of life on Io being a blasted, cursed, irradiated, waterless, sulfurous, freezing cold, searing hot kind of nightmare ball, a place from the video game Doom I would not seem to be a good place to look for science of extraterrestrial life, but if it were to exist there, we talked about some astrobiology speculation on where and how that life might persist.

And now we are back today to round out the discussion, talk about a few more things.

title response precludes a shallow magma ocean. Again published in Nature twenty twenty four, So a bit of context about this.

For the past four decades or so, there has been a question about what powered the vulcan canic corruptions on Io, and it was long suspected for a number of reasons, but not confirmed, that underneath the surface of the Moon there lay a vast planetary magma ocean, sometimes thought to be maybe roughly fifty kilometers deep below the surface, a vast ocean of liquid magma stretching around the planet, which found release points at each of Io's roughly four hundred

active volcanoes. So this was long suspected by some researchers to be the case. But this new paper published in Nature in twenty twenty four has a group of researchers who took information gathered by the NASA Juno mission and used it to argue that the magma ocean hypothesis cannot be correct and instead each volcano is probably powered by its own distinct magma chamber. And I'm going to try

to explain how we get there. So a reminder, going back to part one of this series, volcanic activity on Io was not directly detected until the discovery of a volcanic plume by NASA JPL scientists Linda Morabito in nineteen seventy nine. The image was found in actually navigational images created by the Voyager one spacecraft. Volcanism had been hypothesized by the astrophysicist Stanton Peel beforehand, but this was the

first time direct evidence was identified. But ever since the erupting volcanoes were first discovered, there has been this mystery about what's inside the Moon to feed the eruptions. And I wanted to read a quote here by Juno principal investigator Scott Bolton, who is quoted in a NASA press release about this new paper. Bolton summarizes it saying, quote, since Morabido's discovery, planetary scientists have wondered how the volcanoes

were fed from the lava underneath the surface. Was there a shallow ocean of white hot magma fueling the volcanoes or was their source more localized. We knew data from Juno's two very close flybys could give us some insights on how this tortured moon actually worked. So how did they investigate this? Well? I thought this was pretty cool.

So the Juno spacecraft did flybys of Io in December twenty twenty three and February twenty twenty four, and during those close passes, Juno interfaced with an Earth based tool called NASA's Deep Space Network, which is a network of three equidistant ground based radio antennas on Earth. There's one in California, there's one in Australia, and one in Spain. And the ideas with this equidistant spacing of these antennas, they always at least one of them can maintain contact

with something in space. You never have it going dark. Together, these instruments were able to acquire high precision Doppler readings to detect minute changes in Juno's acceleration, which was in turn able to tell us things about the gravity of iob the gravitational influence of IO, because it was primarily Io's gravity that would have been affecting Juno's acceleration at

these moments. So essentially, researchers were looking for how the gravitational field of IO changes during its tidal stretching cycle, more on that than just a minute, because that would help us know how rigid the Moon is. A more rigid IO would be consistent with a more solid interior, but a more flexible IO would indicate a liquid magma ocean underneath. Now on that sort of flexing and stretching cycle,

IO is in a very close orbit around Jupiter. The average distance between the planet and the Moon is four hundred and twenty two thousand kilometers over the course of its roughly forty two point five hour orbits. Now that is, this is not much further than the distance between the Earth and the Moon, which is about three hundred and eighty four thousand kilometers, except think of how big Jupiter is.

In the words of Scott Bolton, the Juno principal investigator, IO is orbiting a monster, and this has many different effects. We've talked about some of them already, but a big one is a gravitational effect. Gravity follows the inverse square law, meaning that the attractive force between two objects in space is inversely proportional to the square of the distance between them. And another way of thinking about that is, as you get closer to a planet, the force of gravity asserted

on you rapidly becomes greater. So get a little bit closer to Jupiter and you get pulled harder toward it. A strange thing about IO is that in addition to being very close in orbit around a very massive planet, the orbit of this moon is also not circular. It is slightly elliptical, meaning that if you look down from above the orbital plane, you're going to see the orbit being slightly longer in one direction than another. It's a

little bit more oval shaped than a circle. This elliptical orbit is actually because of regular gravitational influence by two more of the Galilean moons, Europa and Ganymede. These moons are in what's called an orbital resonance with Io, which means that their orbits are sort of like small integer

multiples of the orbits of iOS. They frequently line up in the same place as Io as they're going around the planet, and the fact that they continually line up in the same direction over and over means that they sort of stretch Io's orbit in that one direction. So the elliptical orbit of Io means that the distance between Io and Jupiter keeps changing, and so as the distance keeps changing, the string of Jupiter's gravitational pull on Io

keeps changing. Two. And this really affects the Moon because it's always the case that the side of the Moon facing Jupiter experiences a stronger pull than the side that's farther away. The nearer side is pulled harder than the far side, But because of the constantly changing distance between Io and Jupiter, the difference between the pull on the far side and the near side of the planet keeps changing too, And this manifests as what planetary geologists might

call tidal flexing. It's a squeezing, stretching of the solid material that the Moon is made of in the fluctuating gravitational field. You can kind of just imagine this by like holding a rubber ball in your hand and just like squeezing it over and over again. It's a flexing

of the material that the moon is made of. Now, Rob, did you ever do the thing in like the school cafeteria when you were younger, where you you get one of those, you know, cheap metal forks, cafeteria forks, and you bend it back and forth a bunch of times, real fast until it gets hot.

you will find is that the metal heats up. The flexing causes a frictional force within the material that excites the atoms, and it makes the metal hot or at least warm. Similar principle here, The flexing of the Moon by the by the changing gravitational field as it gets closer and farther away from Jupiter causes frictional heat of the inside of the Moon, and that heat is immense. It is so immense that it melts parts of the Moon's interior and this massive build up of internal heat

energy is released to the surface through volcanic eruptions. But this brings us back to the question we started with, what is the nature of the subsurface magma source to read from the paper in Nature quote For decades it has been speculated that this extreme tidal heating may be sufficient to melt a substantial fraction of Io's interior, plausibly

forming a global subsurface magma ocean. Many worlds are believed to have had magma oceans early in their evolution, notably the early Moon referring to Earth's moon there, notably the early Moon, which is thought to have had a shallow magma ocean in the first one hundred million years, caused by the giant impact that birthed the body, which that is not new information in this paper, but that on its own is just a fascinating fact to consider it,

you know. So there is the main theory of the origin of the current Earth and Moon is the giant

impact hypothesis. So the idea is that roughly four and a half billion years ago, during the formation of the Solar System, when the you know, the planets were just accreting, there was a collision between the early proto Earth and some kind of roughly Mars sized object, and this collision caused a fracturing that eventually ended up causing the separation of the material that became the Earth and became the Moon. So that's the common origin of the Earth we have now,

and where the Moon came from. And so the idea here is that for the first one hundred million years or so after that, the Moon probably had a global shallow magma ocean surrounded by liquid by molten rock. Wow would have been cool to see. Perhaps not physically cool, but anyway. So the authors cite that as an example of a global shallow magma ocean surrounding a planetary body or a moon, and then the quote goes on to say Io's extreme volcanism strongly suggests the existence of at

least a partially molten interior. Whether the interior contains a shallow global magma ocean has been an outstanding question since the discovery of Io's volcanism. Now, beyond these theoretical models, were there any recent experiments that would have provided support for the idea of a global magma ocean. I was looking into this and it appears yes, there were some

good reasons from findings that pointed in this direction. Apparently, the Galileo mission took some magnetic measurements that were thought to be consistent with a shallow, shallow reserve of global magma, and I also wanted to flag another argument for the magma ocean, and I came across in a space dot Com article by Keith Cooper, which pointed out that previous data collected by the JUNO mission had actually enabled researchers to create the first global map of Io's volcanic activity.

Rob actually pasted a picture of this global map in the outline for you to look at here. And so it's got little color coded polka dots of different energy levels of volcanic corruptions all over Io's surface. The authors here assembled this map based on near infrared signatures of iOS polar regions. In particular, data collected by previous missions had already done some of this mapping, I think, but had left us with an incomplete picture of volcanic activity

near the poles. And I was reading a space dot com article that quoted study author Ashley Davies, a volcanologist at NASA, JPL and Calteche, Pasadena, and Davies explained their findings by saying, quote before this anal it was thought that Iowe's polar volcanoes were fewer and more powerful than at lower latitudes. We show that polar volcanoes are about as prevalent as at lower latitudes, and actually with lower

emitted power. Suggesting smaller eruptions. And another thing the researchers found is that these findings were interpreted by computer modeling to lend support to the hypothesis of a global subsurface magma ocean. So it seemed like this looked good for the for the magma ocean.

And if it's more rigid, that probably means that it is more solid underneath. And they concluded, based on their findings that Io could not have a global magma ocean underneath its surface. Instead, the Moon must be mostly solid, with individual magma chambers driving the hundreds of volcanoes. The authors of the paper right quote our results indicate that tidal forces do not universally create global magma oceans, which may be prevented from forming owing to rapid melt ascent

intrusion and eruption. So even strong tidal heating, such as that expected on several known exoplanets and super earths, may not guarantee the formation of magma oceans on moons or planetary bodies. And Rob, I've got a little artist's rendition

for you to look at here. This is an artist's impression of the interior of Io informed by these new findings, does not show a global magma ocean instead shows these the pockets, these magma chambers that are leading up to the volcanoes on the surface, some of these volcanoes being connected to plumes that we see erupting far over the

surface of the planet. This has more the look of you know, it's like when you see superheroes and movies that like have the fire inside and you see their skin kind of cracking and then the fire is ready to come out. It looks like it's about to go supermode exactly.

always less dense than the surrounding solid mantle. The melts will tend to ascend, making maintenance of a deep magma ocean dynamically problematic. Conversely, if the melts are dense, for example, if sufficiently iron rich, although a deep magma ocean could then form, it would be hard to explain how any such melt would ascend and erupt. Thus, we conclude that the volcanism scene on iosurface is not sourced from a

global magma ocean. So it seems like that interesting idea is likely put to rest unless something causes us to really reinterpret these results. But despite the magma reserves not being part of a sort of global shared ocean in nature, I still think that leaves the volcanoes and the plumes and the eruptions and the lava lakes no less fascinating and charismatic.

this or are actual captures of this. One of the distinguishing features that you often see with IO is that of these plumes coming up from its surface volcanic eruption that is ejecting material into space, and it is always kind of weird to look at because it feels completely

out of scale, like we're not used to seeing. You know, we've all seen images of volcanic eruptions, and yes they can actually they can look quite alarming from orbit, but this just looks These just look amazing because the Moon in profile has this plume coming off of it, just

this ridiculously far reaching plume of volcanic eruption. And so that's what I want to explore here in this next section, getting into like what exactly this is, what is it mean for not only IO, but for the the basically the entire orbital realm of Jupiter itself.

exaggeration of reality. And that's what the scale of these things really looks like.

We have a robust atmosphere, We have resulting wind resistance and sufficient gravity to place the necessary escape velocity beyond what even a very powerful terrestrial eruption is capable of reaching.

other inner planets. On Earth's own moon it's two point thirty eight kilometers per second, and on Io the number I've seen is two point five five eight. So just to give you a little frame of reference for what we're talking about here again coming back to what does Earth have that a lot of these other suspects don't you know? It has. It has the gravity, it has

the robust atmosphere and so forth. So this all adds up to a greater necessary escape velocity for anything that is leaving the surface of the planet or any point within the atmosphere of the planet, and hoping to free itself of our orbital dominion. Now one thing I want to go ahead, get out of the at the top here there. I think a lot of people have probably heard the legendary manhole shot into space story via Operation plumb Bob.

These were atomic tests in nineteen fifty seven. The idea here was that you had these test wells for atomic detonations with a metal cap on the top, essentially a manhole cover, and at least one of these blasted the cap off, and it was said that it achieved such velocity. In fact, I think the number that is often cited is six times the necessary escape velocity and therefore flew off into space and is potentially still out there well.

According to a twenty twenty two Snop's article by Bethania Palma, there's nothing actual actually out there to back this up. This all seems to stem from a comment by Robert Brownly, who worked on the project, who remarked that the manhole cover in question would have been blasted off at six times the necessary escape velocity. It apparently went flying, but that's all that's really known. We don't know if it was launched into space, and if it was, we have

no records or recording of it. I think it's also been mentioned that it's possible that it would have burnt burnt up on the way up as well. So you know, we have to consider all these options. But there's no like clear evidence that this thing actually made it into orbit or beyond orbit and so forth.

it's and rocket science has come a long way. It's ultimately a lot more dependable than trying to blast into space on a volcano, which again probably wouldn't give you the exactly the push you needed anyway.

to mention Project Ryan here. This has come up on the show in the past because it is, you know, it's an early concept of how we might achieve interplanetary travel. It was a nuclear pulse spaceship concept from the nineteen fifties and sixties. I think a lot of you may be familiar with this. Essentially built around the idea was built around the concept you could propel a craft through space via a series of nuclear detonations behind the craft.

Not to be confused with nuclear thermal rockets such as the Nerva project, in that you'd have a nuclear reaction that was heating fuel rather than depending on a chemical reaction to do so.

always found. I mean, it's it's it's preposterous and yet reasonable, amazing in its own right, and you know, in Inner Yourself to the Stars, Yeah, yeah, and uh yeah, it's it's. It's one that I've come back to a few different times.

But it's one of Sagan wrote about as well. Actually looked up an old like press briefing where someone asked Sagan about it, and you know, he pointed out he'd written about it in Cosmos or I don't remember if you'd written about it in Cosmos or if you just discussed it on the television series, but you know, pointed out that like, Okay, well, this is actually not a bad way to go ahead and get rid of some of our atomic weapons. Let's use them to propel a spaceship.

But of course there are all these various hazards to such a technique as well. Some of these we'll get into here in the discussion. So I was, you know, I was mostly familiar with the concepts involved here, the

potential benefits and the downsides. But one thing that I didn't quite realize is that early models of the project Orion nuclear pulse spaceship during the fifties and sixties actually considered it not only for propelling a vehicle through space, but for using it in liftoff in order to achieve escape velocity from Earth.

test site. The mass of the vehicle on takeoff would have been on the order of ten thousand tons, most of which would have gone into orbit at takeoff, the zero point one kiloton yield pulse units would be ejected at a frequency of one per second. As the vehicle accelerated, the rate would slow down and the yield would increase until twenty kiloton pulses would have been detonated every ten seconds. The vehicle would fly straight up until it cleared the

atmosphere so as to minimize radioactive contamination. This is one of the big hazards and downsides to this whole concept is that you would it would entail detonating multiple multiple atomic weapons in this model within the atmosphere. But even if you weren't using that within its atmosphere to achieve liftoff, if you were going to the program where okay, once you get your spaceship away from Earth, then you can start dropping bombs in order to accelerate. Even then you're

still causing all of these detonations. And then what happens when you reach sure destination. There are some models that were outlined that would call for detonating bombs as you landed, thus like nuking the landing site ahead of your arrival. And if there are people on board, well they're gonna have to deal with the literal fallout of all of that.

The original concept was created by Ted Taylor and Freeman Dyson, and Freeman Dyson's son, George Dyson, claims, historian of science, wrote about all this in the book project Orion, The True Story of the Atomic Spaceship, and he points out quote these early four thousand ton ground launched versions of Orion specified the ejection of about eight hundred bombs raging and yield from zero point fifteen kilotons at sea level to five kilotons in space to reach a three hundred

mile orbit around Earth. Points out that each bomb would have weighed around half a ton. Less yield would be necessary at lower out tod since the thicker air itself would absorb energy and add to the kick against that plate. But then you would need more yield. You'd have to steadily increase the yield of the detonations as the vessel

was propelled upwards. And this would have all required like tight precision and exactly how you're detonating these bombs and even how you're getting them back there underneath the ship, like is it a trapdoor or is there some sort of a you know, some sort of a targeted rocket system that launches them alongside the vessel and then back underneath it. You know, you would have to work out all of those problems. So that's about eight hundred bombs.

The original design called for about two thousand bombs or two thousand pulse units, far more than needed to reach orbit according to their calculations, but that was because they'd set their sites pretty high. Their slogan was Mars by nineteen sixty five, Saturn by nineteen seventy, and they were talking about like crews of one hundred and fifty people. So this was a really ambitious concept. Obviously, this is not the way it all worked out.

it's ultimately more attractive. Like Sagan said, it's like, well, that's one way to get rid of the weapons, or at least that's the way he put it at one point. Now the concept here continued to again they ended up moving away from the idea of it potentially blasting off of the surface of the Earth like this via atomic

weapon detonations. It had many powerful supporters, but it never came to fruition for a variety of reasons, including cost, including risk, and of course including international treaties about nuclear testing. George Dyson points out that, yeah, you had these various drawbacks to such a program, including the idea that if you were going to use detonations while potentially a landing a ship in another world, again, you would be pre

contaminating the landing site. So even if you even if that wasn't going to make it too you know, radioactive for then humans to venture out on the surface of this destination world, you're still messing with what you were going to explore to begin with. You know, so so many different reasons to not go in this direction. Now you might be wondering was there another way to get something into orbit from Earth's surface without some sort of

an explosion. Well, there has been research into the use of centrifugal force, and such research actually continues at least as a rocket aid to decrease the dependence on traditional rockets. You know, you can think essentially like slingshots in terms of like the basic fundamentals here, this is the sort of thing we could potentially come back and do a more dedicated episode on this idea, because again there as at least one company out there that continues doing a

lot of well funded work in this area. Now elsewhere in speculation and in science fiction, there are some ideas related to directed panspermia to consider, so directed PAMs spermias. Of course, this would entail the intentional seeding of other worlds with life, and in some creative takes on what this might look like, it might entail some manner of biological propulsion, maybe some sort of biocanon that enables a seed of some sort to escape from one world's gravity,

drift through space and find another world. And we actually saw a vision of what this might look like in a recent film that we discussed on Weird House Cinema, Beyond the Mind's Eye.

I think they're called plasma bugs in that, and these are some sort of organic cannon system.

to get it off the planet. And interestingly enough, unless I'm mistaken, they don't have any kind of way of like launching it directly back up with their you know, entirely biological civilization. Instead, they depend on something called capillary towers, which are like organic space elevators. So they just have the big ships in orbit suck it all up back off the surface of the planet, which I guess is one way to potentially do this.

had direct evidence of the volcanoes. One of the indications that there might be something strange going on with Io was he said that they had already detected a huge doughnut shaped tube of atoms in orbit around Jupiter basically within the sort of the same position as the orbit of the moon Io made up of just like just isolated atoms of things like sulfur and potassium and sodium, and for some reason that's just going around the planet.

amplifying Jupiter's magnetosphere. So the ioplasma Taurus plays a major role in strengthening the most powerful magnetosphere in the Solar System. I mean, the magnetosphere of Jupiter almost reaches the orbit of Saturn.

particles and I owe as a major contributor. These radiation belts pose an additional obstacle to missions to any missions to the Jovian moons, particularly any possible future missions that might feature live crew members, because this would expose them to lethal doses of radiation for like hours at a time potentially, and it poses a risk to equipment as well. So any mission through these belts requires, on one hand, additional navigation precision to avoid, as the ESA points out,

low latitude orbital paths around Jupiter. And also you just need to have additional shielding and protection for any gear because I've read that it essentially would be it would be a case where whatever kind of equipment was aboard one of these craft, it would encounter as much radiation as a terrestrial satellite would endure over the course of multiple decades.

if you have feedback in anything we've discussed in these episodes. Likewise, are there other moons that we've covered in the past, Jovian moons, the moons of Saturn, and so forth that you think deserve a second, more detailed examination on the show. If so, right in, let us know and we will consider giving it a go.