Speaker 1: Hey, you, Welcome to Stuff to Blow your mind. My
Speaker 1: name is Robert Lamb and I'm Joe McCormick. And it's Saturday.
Speaker 1: The vault hangs open. And of course today's Vault episode
Speaker 1: is more than a regular Vault episode. It is a
Speaker 1: cosmic odyssey. That's right. We are going to meet Jupiter's children,
Speaker 1: the Galileean moons, the Jovian offspring. I don't have another synonym,
Speaker 1: the moons of Jupiter. Yes, you will go there. Yeah,
Speaker 1: it's like its own Solar system. Uh and and each
Speaker 1: one is just a fascinating, literally otherworldly destination. We can't
Speaker 1: wait till you get to the end and experience the
Speaker 1: fiery planes of Io. Welcome to Stuff to Blow your mind.
Speaker 1: From how Stuff Works dot com. It really is darker
Speaker 1: out here in the outer Solar System. Your space freighter's
Speaker 1: one remaining forest dome struggles but barely scrapes along, surviving
Speaker 1: the plants still put out leaves. It seems only yesterday
Speaker 1: that you defied orders to jettison the dome and return
Speaker 1: to Earth immediately, but instead you absconded. You took the
Speaker 1: plant life capsule, and you flew away away from the Sun,
Speaker 1: out into the Outer Solar System. You have only the
Speaker 1: forest and a pair of robots now to accompany you
Speaker 1: through this long twilight. You'd hope to pass beyond Jupiter
Speaker 1: and find refuge within the rings of Saturn, but the
Speaker 1: great gas giant will not be defied. It's massive gravity
Speaker 1: tugs at your humble freighter. The red eye of its
Speaker 1: century spanning storm taunts you as Jupiter drags you into
Speaker 1: the orbital realm of its many moons. But still there's hope.
Speaker 1: Perhaps one of the four Eater moons the Galilean moons
Speaker 1: will offer some place of refuge. But which of these
Speaker 1: strange and hostile worlds might serve as a new home
Speaker 1: for you and this geodesic refugium from Old Earth's lost
Speaker 1: bio diversity. Hey, welcome to stuff to blow your mind.
Speaker 1: My name is Robert Lamb and I'm Joe McCormick, and
Speaker 1: you should imagine yourself in the scenario we just described.
Speaker 1: You're in some kind of spacecraft, hopefully one that has
Speaker 1: some some plants along with it to keep you sustained
Speaker 1: through the long Outer Solar System journey, and no hostiles
Speaker 1: you know, more th onboard exactly, and you are caught
Speaker 1: in the gravitational influence of the planet Jupiter. You didn't
Speaker 1: mean to end up this way, but hey, you know,
Speaker 1: Jupiter's gravity is something that's difficult to escape. And now
Speaker 1: now you're stuck spiraling in towards Jupiter, slowly decaying in
Speaker 1: your orbit, getting closer and closer all the time. But
Speaker 1: one thing you have noticed is that you will get
Speaker 1: to see a close up view and perhaps, if you're
Speaker 1: lucky enough, maybe land on Jupiter's four largest moons, known
Speaker 1: as the Galilean moons. This is the tour we want
Speaker 1: to take you on today. Indeed, these moons are of
Speaker 1: course of immense interest to science. Now, one analogy that
Speaker 1: I think is interesting to help us understand the way
Speaker 1: the Jupiter system and its gravitational influence works, is to
Speaker 1: think of Jupiter kind of like a star within our
Speaker 1: solar system, like it's its own star, and the planet,
Speaker 1: the moons that are going around Jupiter a kind of
Speaker 1: like planets orbiting this solar system within a solar system. Indeed,
Speaker 1: because it is a massive planet, it's mass is three
Speaker 1: hundred and seventeen point eight to eight uh times that
Speaker 1: of Earth, and uh it's of course a gas giant
Speaker 1: it's mostly gas. It might have a solid core about
Speaker 1: the size of Earth at the center, possibly a rocky
Speaker 1: ice covered core with insane levels of atmospheric pressure and
Speaker 1: temperatures hotter than the surface of the Sun. And Jupiter
Speaker 1: features no fewer than sixty seven lunar objects. That includes
Speaker 1: fifty confirmed moons and seventeen unconfirmed or provisional moons. Yeah,
Speaker 1: and these are the ones we know about. Yeah, but yeah,
Speaker 1: and they've got cool names like Metis and and Drastia.
Speaker 1: And then of course there's also the There are also
Speaker 1: three faint gossamer rings around Jupiter as well, certainly not
Speaker 1: as robust as the Saturn's rings, but they're there nonetheless.
Speaker 1: So we should back up and start at the beginning,
Speaker 1: because we're learning a whole lot more about Jupiter's moons,
Speaker 1: especially Jupiter's Galilean moons, the ones we're going to focus
Speaker 1: on today, the four largest moons, But we were learning
Speaker 1: a lot more about that recently. But we've known about
Speaker 1: Jupiter since ancient times because you don't need a telescope
Speaker 1: to see Jupiter. That's right, it's visible from Earth, and
Speaker 1: so it factors into many ancient systems of astrology by
Speaker 1: virtue virtue of that cosmology. The Roman name Jupiter stems
Speaker 1: from the king of the gods, but the planet to
Speaker 1: plays a role in many cultural beliefs. In Chinese astrology,
Speaker 1: for instance, it's the character of Foo uh character of
Speaker 1: foods tied to Jupiter, and he's the embodiment who is Foo.
Speaker 1: He's the embodiment of good fortune uh, symbolized in a
Speaker 1: scholars dress, and he's cradling a child. The three stars
Speaker 1: that you'll often see. You often see these three statues
Speaker 1: of these men in Chinese households, Chinese businesses uh. And
Speaker 1: they each kind of they each represent a different form
Speaker 1: of of idealized to success. So one is old and
Speaker 1: wise one and one is a successful with his family,
Speaker 1: and the other one is successful with business. I always
Speaker 1: think it's interesting that we see this cross cultural phenomenon
Speaker 1: of associating planetary bodies or objects in the sky with gods. Yeah,
Speaker 1: it's fascinating because you see this in other systems as well.
Speaker 1: For instance, the Vedic astrology, Jupiter is everything from the
Speaker 1: dwarf incarnation of Vishnu to to Ganesha or sometimes Brahma.
Speaker 1: So it it varies with within that system. But yeah,
Speaker 1: that Jupiter always seems to have a pretty cushy role
Speaker 1: within a given a given cultures astrology. Yeah, so we
Speaker 1: mentioned that ancient cultures knew about Jupiter because you can
Speaker 1: see it with the naked eye, But one of the
Speaker 1: things they didn't know was much more about Jupiter other
Speaker 1: than it being a point of light. That's right. For instance,
Speaker 1: when we think of Jupiter, what what do we picture?
Speaker 1: We picture that big, big gas giant with a big
Speaker 1: red eye, right, red spot, Yeah, the giant red hurricane
Speaker 1: on Jupiter's outer surface. Yeah, it's great to focus in
Speaker 1: on on the red storm because it helps us really
Speaker 1: understand Jupiter and our relationship to Jupiter. Because, for one,
Speaker 1: on one hand, that storm has not been there forever, uh,
Speaker 1: and it will not be there forever, but it spans centuries,
Speaker 1: it's been there as long as we've been able to
Speaker 1: see Jupiter in that kind of detail. Uh. And it
Speaker 1: in the storm itself is two to three times the
Speaker 1: size of Earth. Uh. So that helps put again the
Speaker 1: massive scale of Jupiter. Can you imagine in reference if
Speaker 1: on Earth we had storms that lasted for I don't know,
Speaker 1: hundreds of years. I've I've thought about it, like when
Speaker 1: you start teasing apart our weather system and you start
Speaker 1: looking at the different the different systems involved there, and
Speaker 1: the different factors that end up decreasing a hurricane's power.
Speaker 1: You know, what if those were not there? What if
Speaker 1: you had a scenario where the storm was essentially just
Speaker 1: a permanent part of the planet as a mortal individual
Speaker 1: would experience it. You know, that would be a great
Speaker 1: set up for like a sci fi thriller. Imagine the
Speaker 1: weather conditions on Earth change that such that tornadoes tend
Speaker 1: not to dissipate on their own unless you have to.
Speaker 1: You have to find a way to essentially dissipate tornadoes
Speaker 1: by force. Yeah, indeed, and that that red storm on
Speaker 1: Jupiter is dissipating slowly but still there as of this recording. Now,
Speaker 1: as far as how far away Jupiter is, it's fo
Speaker 1: four million miles seven million kilometers or five point two
Speaker 1: astronomical units uh from the planet Earth. Okay, so we
Speaker 1: know Jupiter is a gas giant, but you always wonder
Speaker 1: what's inside a gas giant. I mean, is it all
Speaker 1: just gas or is there something solid inside there? Well,
Speaker 1: we don't know for certain. We Uh, the atmosphere of
Speaker 1: Jupiter is mostly hydrogen and helium, but it might have
Speaker 1: a solid core about the size of Earth, and this
Speaker 1: might be an icy covered core with just really insane
Speaker 1: levels of atmospheric pressure and temperature is hotter than the
Speaker 1: surface of the Sun. So it's very much the core
Speaker 1: and not you know, not the surface of the planet.
Speaker 1: But but you know, you can't help it. Imagine, well,
Speaker 1: what if what if you could what if you could
Speaker 1: transport yourself down to the physical surface of this gas world.
Speaker 1: It would of course be just unimaginable with one of
Speaker 1: the most hostile environments you can even envision in the
Speaker 1: Solar System. Yeah, it's pretty rough. And one of the
Speaker 1: things that's going to come up repeatedly I think today
Speaker 1: is how Jupiter, though it may look very serene and
Speaker 1: beautiful to us, is it kind of meets that analogy
Speaker 1: I worked out at the beginning about it being like
Speaker 1: a star, because Jupiter is it has massive gravitational influence,
Speaker 1: it's very electrically active, and it's just it's just full
Speaker 1: of radiation. You don't want to go near Jupiter. Yeah, Yeah,
Speaker 1: to be sucked into Jupiter would be to be sucked
Speaker 1: into death, really, and that's one of the things we're
Speaker 1: out lying in the intra material. Yeah, so it's really
Speaker 1: unfortunate that we're slowly spiraling into Jupiter in today's thought experiment.
Speaker 1: But but we should at least take the time to
Speaker 1: appreciate the sites we'll see along the way. That's right.
Speaker 1: And uh and and maybe if we're lucky, grasp onto
Speaker 1: them and uh and seek refuge refuge upon them, because
Speaker 1: even though they are all very hostile worlds in their
Speaker 1: own right, uh, there's still a better bargain and they
Speaker 1: still present a better chance for not only the potential
Speaker 1: like the real life potential for for human visitation, but
Speaker 1: in some of these cases we'll discuss the possibility for
Speaker 1: extraterrestrial life. Yeah, Okay, Now, Jupiter is not entirely unexplored today.
Speaker 1: We've actually sent quite a few probes Jupiter's way that
Speaker 1: have that have orbited Jupiter and made various observations about
Speaker 1: it and it's major satellites, right, that's right. To date,
Speaker 1: NASA has sent nine space missions to or buy the
Speaker 1: gas giant. So we're talking to the the Pioneer Program seventy four,
Speaker 1: the Voyager Program seventy nine. Ulysses into Cassini in two
Speaker 1: thousand new horizons in two thousand seven. Also, Galileo is
Speaker 1: a big one, and that's a through two thousand three Juno.
Speaker 1: That one's of course a very current that's two thousands sixteen.
Speaker 1: And uh, there are various additional missions and schemes for
Speaker 1: missions in the works. Oh yeah, I know the e
Speaker 1: s A is working on the Juice Explorer, right, the
Speaker 1: Jupiter Icy Moon Explorer, which I don't know. I don't
Speaker 1: know if I agree with the wisdom of calling it Juice.
Speaker 1: It's it seems just a little too cool, like like
Speaker 1: it's like the name doesn't need to be that cool
Speaker 1: because it's going to Jupiter exactly know, it's going to
Speaker 1: the moons of Jupiter. That alone is is just mind bending. Yeah,
Speaker 1: and so hopefully it's going to explore three of the
Speaker 1: four main moons we're going to talk about today, the
Speaker 1: icy moons of the icy Galilean moons of Jupiter. And
Speaker 1: it's launching in two right, Yeah, I believe that's the
Speaker 1: current plant. And NASA is currently putting together the Europa
Speaker 1: Multiple flat by mission for the same time period. Alright,
Speaker 1: So I mentioned earlier thinking about the Jupiter system like
Speaker 1: a solar system within a solar system. And if you
Speaker 1: do that, of course you've lots of bodies out there.
Speaker 1: We mentioned the sixties seven known satellites of Jupiter, things
Speaker 1: that are orbiting, but a lot of them are very small.
Speaker 1: If we do think about Jupiter like a solar system,
Speaker 1: it has four main planets. That's right, they stand out
Speaker 1: and the most due they're just their sheer size. And
Speaker 1: these are Calisto, Ganymede, Europa, and Io. So you can
Speaker 1: think of them as it's four scoops on a on
Speaker 1: a Jovian ice cream cone, and you get the following
Speaker 1: flavors of scoops. You'll get salty craters, magnets, ice, and
Speaker 1: of course lava lava. That's a good flavor. Now, Robert,
Speaker 1: did you know that you seem to be you're a
Speaker 1: fan of ice cream metaphors? I did. I use them
Speaker 1: when thinking about planets. I use them when thinking about
Speaker 1: the brains. Though. Is this a good way of explaining
Speaker 1: things to children? Did they just really grasp onto ice
Speaker 1: cream metaphors? You know? I don't know. I guess it's
Speaker 1: a good way to explain it to the child within Um, yeah,
Speaker 1: I mean maybe it comes back to sort of like
Speaker 1: a Sesame Street mentality. You know, like I grew up
Speaker 1: watching these visual representations, and it seems like it seems
Speaker 1: like there were more than one Sesame Street skit that
Speaker 1: had ice cream in them, So maybe that that ended
Speaker 1: up sticking. I guess that does make sense. But it
Speaker 1: is interesting to think about the flavors of each of
Speaker 1: these moons because they kind of do each have their
Speaker 1: own flavor, especially the inner two I think, yes, yeah,
Speaker 1: each one is is its own weird world with its
Speaker 1: own properties, its own unique landscape, and that's why we
Speaker 1: wanted to take our listeners on a journey through each one. Now,
Speaker 1: one thing we should mention about all of these worlds
Speaker 1: that's kind of different than most of the inner planets
Speaker 1: of the Solar system that we think about that have
Speaker 1: like a soul, uh you know, a solar rotational day,
Speaker 1: is that all of these moons are tidally locked with Jupiter.
Speaker 1: The same side of the Moon always faces in towards Jupiter. Yes,
Speaker 1: almost like they're completely obedient. They dare not look away
Speaker 1: from their their master, right yeah. Or or it's kind
Speaker 1: of like in in Mario, you know, they're afraid to
Speaker 1: turn their back on the ghosts because when the ghost
Speaker 1: comes to get you. So we mentioned that these are
Speaker 1: referred to as the Galilean moons, and we should probably
Speaker 1: explain first how they were discovered and why they're called
Speaker 1: the Galilean moons. Today. The obvious conclusion you might reaches
Speaker 1: that they're named after Galileo. You know, he's an astronomer,
Speaker 1: and if you assume to that, you'd be right. That's
Speaker 1: where the name comes from. That's right. And I think
Speaker 1: most of you are probably familiar at least a little
Speaker 1: bit with Italian astronomer slash heretic Galileo galile He who
Speaker 1: was born in fifteen sixty four died in sixteen forty two,
Speaker 1: and he was a true renaissance man, uh in the Renaissance.
Speaker 1: He was also a physicist and engineer, a philosopher, a mathematician,
Speaker 1: a true superstar in the history of science and really
Speaker 1: in the history of human civilization in general. It's really
Speaker 1: it's really difficult to to overstate the importance the importance
Speaker 1: of Galileo. Yeah, I mean often today scientific struggles against
Speaker 1: ingrained orthodoxy are framed in terms of Galileo's struggle against
Speaker 1: the the scientific and religious orthodoxy of the day. Both
Speaker 1: of which opposed him. Yeah, well, our listeners a little
Speaker 1: more about the controversy surrounding helio centritism. All right, yeah, well,
Speaker 1: so you'll probably associate Galileo with helio centrism. The idea
Speaker 1: that the planets in the Solar System go around the
Speaker 1: Sun could have also the day in the at the
Speaker 1: time meant that everything in the universe goes around the Sun.
Speaker 1: Of course, now we know that's not correct, but we
Speaker 1: were still very much working our way outward and our
Speaker 1: understanding of the universe. But it was certainly onto something
Speaker 1: in the idea that the Earth goes around the Sun
Speaker 1: and not the other way around the Earth end all
Speaker 1: the other bodies in the Solar System. And so Galileo
Speaker 1: did not come up with the idea of heliocentrism. He
Speaker 1: didn't invent this. This was a Copernican idea. It was
Speaker 1: already in circulation, and Galileo was one of the Copernican
Speaker 1: astronomers of the seventeenth century. However, a version of the
Speaker 1: geocentric Aristotelian Ptolemaic model was what was dominant in the day,
Speaker 1: was what most people believed. And in this model, the
Speaker 1: Earth is It's not just that the Sun goes around
Speaker 1: the Earth, and the Moon goes around the Earth and
Speaker 1: all that. It's that the Earth is literally the center
Speaker 1: of motion in the universe. So by by a principle
Speaker 1: that centers on the Earth, the whole universe just goes
Speaker 1: all goes around us. So we're what everything else is
Speaker 1: focused on. And the role of Galileo's discovery is that
Speaker 1: in observing the sphere of Jupiter's gravitational influence, Galileo provided
Speaker 1: new evidence against that type of geocentrism that dominated in
Speaker 1: his day, and one one piece of evidence became apparent
Speaker 1: in January six when Galileo made his first round of
Speaker 1: observations through a telescope looking at Jupiter. So Galileo also,
Speaker 1: like not inventing helio centrism, did not invent the telescope,
Speaker 1: but what he did do was improved it. He made
Speaker 1: a series of improvements to a design of the telescope
Speaker 1: that allowed him to resolve farther objects than ever before,
Speaker 1: and by the time Galileo got the magnification power of
Speaker 1: his telescope cranked up to twenty times, he aimed at
Speaker 1: the planet Jupiter and he saw something really weird. As
Speaker 1: we mentioned earlier, you can see Jupiter with the naked eye, right, yes, yeah,
Speaker 1: And so ancient astronomers had been seeing Jupiter for a
Speaker 1: long time. They're already aware of its existence. But what
Speaker 1: Galileo saw when he focused on Jupiter was interesting. He
Speaker 1: saw stars. He saw three stars lined up right next
Speaker 1: to Jupiter, almost as if strung along a spear extending
Speaker 1: out through Jupiter's equator. So Galileo made a note of this,
Speaker 1: and he decided to check back on it later. Now,
Speaker 1: if those had been stars that were just in the background,
Speaker 1: you know, if they just happened to line up with
Speaker 1: Jupiter from the star field beyond the next time you
Speaker 1: looked at Jupiter, they shouldn't be there, right, because Jupiter
Speaker 1: should have moved on relative to the background starfield. Right.
Speaker 1: They shouldn't be following the planet because there would be
Speaker 1: distant opjecs ex on the planet exactly. But instead the
Speaker 1: stars followed Jupiter. Where Jupiter went, the spear of stars
Speaker 1: followed and they change their positions relative to Jupiter. And
Speaker 1: so after some observation, Scalio realized that there are actually
Speaker 1: four stars on this spear, not just three. And the
Speaker 1: conclusion he realized was that these weren't stars. The star
Speaker 1: spear was not a star spear, it was a moon spear.
Speaker 1: These are moons that are orbiting Jupiter the same way
Speaker 1: Earth's moon orbits the Earth. And so, okay, well, so
Speaker 1: Jupiter has moons. What does that mean for the cosmological
Speaker 1: debate of the day. Well, if there are moons orbiting Jupiter,
Speaker 1: it disproves the Aristotelian principle that Earth is the universal
Speaker 1: hub of motion of planetary bodies. Those moons don't orbit
Speaker 1: the Earth, they orbit something else. And so this gives
Speaker 1: you a kind of general principle of things orbiting things
Speaker 1: rather than everything orbiting Earth. And it's clear that there's
Speaker 1: more than one center of motion possible. There at least
Speaker 1: two that now that we know of Jupiter and Earth.
Speaker 1: And if there are two, you can assume they're probably
Speaker 1: more than two. And this eventually led to the type
Speaker 1: of thinking that showed us what was really out there
Speaker 1: in terms of heliocentrism in the way gravity works. Now,
Speaker 1: I should also add that the discovery of Jupiter's moons
Speaker 1: wasn't unique to Galileo, and he wasn't even necessarily the
Speaker 1: only or first person to have discovered them. I found
Speaker 1: accounts that at least one other guy, a German astronomer
Speaker 1: named Simon Marius, discovered them independently at around the same time.
Speaker 1: And it's also been suggested that an ancient Chinese astronomer
Speaker 1: named Gone Day might have discovered one of the moons
Speaker 1: of Jupiter in the fourth century b c e. When
Speaker 1: he said that he saw around Jupiter a small red star. Now, technically,
Speaker 1: under the right circumstances, the moons of Jupiter should be
Speaker 1: visible to the naked eye from Earth, and the only
Speaker 1: thing that really prevents it is that Jupiter is too bright.
Speaker 1: You look up at Jupiter and it's it's so bright
Speaker 1: that it drowns out other tiny points of light that
Speaker 1: are close to it, so you can't usually see them.
Speaker 1: But if Jupiter weren't there, you should be able to
Speaker 1: see these objects. Oh but you know what, I think
Speaker 1: that sound means that we're coming up on Jupiter's first
Speaker 1: gal and moon spiraling in from the outside, and that's
Speaker 1: going to be the moon Callisto. Yes, and I think
Speaker 1: this is this is a pretty good pit stop to consider.
Speaker 1: So Callisto is about the size of the planet Mercury.
Speaker 1: It's the third largest moon in the entire Solar System,
Speaker 1: and it's the outermost of the four Galileean moons. As
Speaker 1: we've discussed, uh, it orbits beyond Jupiter's main radiation belts.
Speaker 1: So Jupiter is highly radioactive, it's putting out a lot
Speaker 1: of scary stuff, but Callisto is far enough away that
Speaker 1: it's relatively safe. That's right. Yeah, we're we're outside of
Speaker 1: that that death lea, the death zone. Yeah. It's also
Speaker 1: the most heavily cratered o chick in the Solar system.
Speaker 1: So that's interesting. Yeah, this is this is really fascinating.
Speaker 1: So as we as we as we we get closer
Speaker 1: and closer, as we're able to observe the surface of
Speaker 1: Callisto and maybe i know, hopefully even get out even
Speaker 1: land our vessel and find a semi permanent home on
Speaker 1: this uh this this strange moon. You would find that
Speaker 1: the surface, to to walk the surface of Callisto would
Speaker 1: be to walk a dead landscape of craters and occasional
Speaker 1: small icy peaks. And this surface, this landscape has not
Speaker 1: changed in four billion years. Yeah, that's one of the
Speaker 1: things that we often associate having heavy cratering with, right,
Speaker 1: like more cratering. You see the older the surfaces, because
Speaker 1: what does cratering mean? It's been like that a long
Speaker 1: time without any kind of repaving. That's right. This is
Speaker 1: the last time Callisto suffered any extensive resurfacing was four
Speaker 1: billion years ago. And there are no plate tectonics, there
Speaker 1: are no volcanoes, a no active geology to alter the landscape.
Speaker 1: So it seems like a kind of quiet, serene, dead Yeah.
Speaker 1: I mean it's like a dinosaur world. Right. It's like
Speaker 1: the moon itself is only four point five billion years old,
Speaker 1: and again it hasn't changed in four billion um. It's
Speaker 1: also the darkest of the four moons that we're discussing here,
Speaker 1: in the least dents. So Callisto's composition is about half
Speaker 1: water ice and half rocky material, and the mean surface
Speaker 1: temperature of Callisto is negative two and eighteen point forty
Speaker 1: seven degrees fahrenheit, and the thin atmosphere consists of mostly
Speaker 1: carbon dioxide. Okay, so it may be very quiet and
Speaker 1: serene on this on this seemingly dead rock. But should
Speaker 1: we take away from that that Callisto is definitely not
Speaker 1: a place to look for signs of life. Well, I
Speaker 1: think we've both watched enough science fiction to know that
Speaker 1: that world that you land on it seems dead is
Speaker 1: never It's not always really that dead. I have a
Speaker 1: sidetrack to take here. Do you notice how in science fiction,
Speaker 1: whenever you land on a planet that does turn out
Speaker 1: to have hostile aliens on it, you never land where
Speaker 1: the aliens are doing something. Right, then you always land
Speaker 1: in somewhere where there's no sign of them, and it's
Speaker 1: only after exploring for a while that you run into them. Yeah,
Speaker 1: it would be it would be interesting to have that
Speaker 1: story where the ship touches down and all the hideous
Speaker 1: night creatures are already out, you know, viciously killing the
Speaker 1: eight creatures that lived there during the day. I like
Speaker 1: how the the viciously killing motion you made was like
Speaker 1: lopping with shears. Yeah, Like I'm thinking like two big
Speaker 1: old pincher arms that are just for stabbing apes. Um,
Speaker 1: so we're not thinking about big pincher arms on Callisto.
Speaker 1: But there might be something to look for here, right,
Speaker 1: That's right. Surprisingly, for a world that we've described in
Speaker 1: these terms, you know, it's just being this dead crater landscape.
Speaker 1: There is some talk of life on or more specifically
Speaker 1: within Callisto. Specifically the stability of an electric, salty subsurface ocean.
Speaker 1: So you're probably wondering, well, where do we Where did
Speaker 1: we dream up this idea? How do you say? Who
Speaker 1: says yeah, because you could say you couldn't you say
Speaker 1: that about any world like, oh, well, maybe there's an
Speaker 1: ocean beneath mercury. Now, so there's life on the moon.
Speaker 1: Come on, it's the spiders from that what's that horrible movie?
Speaker 1: Horrible movie with spiders. Pick one. It's a rich, rich tapestry. Okay, sorry,
Speaker 1: who said this about Callisto? Well, this comes from a
Speaker 1: doctor Krishawn K. Corona of U c l A and
Speaker 1: his colleagues who examined Galileo's measurements, Not not Galileo the scientists,
Speaker 1: but Galileo the spacecraft that we mentioned earlier. Uh. They
Speaker 1: examined galileos measurements of Callisto's magnetic field, and they noticed
Speaker 1: that the magnetic field fluctuated in time with Jupiter's rotation. Okay,
Speaker 1: so what does that mean. It means that Jupiter's powerful
Speaker 1: magnetic field was creating electrical currents inside of Callisto, and
Speaker 1: those currents, in turn created a fluctuating magnetic field. Around Callisto.
Speaker 1: Now for that to happen, you need a conduct her
Speaker 1: and that thin uh atmosphere crater skate that we've touched
Speaker 1: on earlier, that's just not gonna cut it. What would work, however,
Speaker 1: is a salty layer of melted ice down there, a
Speaker 1: subsurface ocean electrolytes. Yeah, it's what alien life craves. Yeah,
Speaker 1: a a a sub world gatorade ocean, if you will,
Speaker 1: so cautiously, very cautiously, there is the potential for extreme
Speaker 1: file life within this theorized subsurface ocean. There's liquid water,
Speaker 1: perhaps salty, there's energy. So we'd be talking micro if
Speaker 1: we were to you know, consider life using our only
Speaker 1: model of it, which is Earth life, we'd be talking
Speaker 1: micro organisms like our keya bacteria, salt loving bacteria. There
Speaker 1: wouldn't be any gigantic electronic moon whales. There wouldn't be
Speaker 1: any uh, there's certainly no you know, mandible ape stab creatures.
Speaker 1: But of and of course, it would also be very cold,
Speaker 1: and the ocean would only be heated by radioactive elements.
Speaker 1: So it's a very very very very hostile environment that
Speaker 1: we're picturing here. But based on our understanding of life
Speaker 1: on Earth, it would not be impossible for something to
Speaker 1: have evolved and and even thrive there. Still. Yeah, and
Speaker 1: though we do want to point out that when we
Speaker 1: think about what hostile to life is, we're thinking about
Speaker 1: hostile to Earth life, right, And of course the Earth
Speaker 1: environment might be incredibly hostile to organisms adapted to some
Speaker 1: other kind of world. So, like you know, on Earth,
Speaker 1: on Earth we have oxygen and oxygen atmosphere. Oxygen is
Speaker 1: nice to us because we're adapted to it, but it
Speaker 1: could be highly corrosive to some other type of organism. Yeah, indeed,
Speaker 1: so you know, with all this, it's it's relative based
Speaker 1: on our human perspective and our our preference for all
Speaker 1: things that support human life. Now, as far as the
Speaker 1: exploration goes, we've we've had nothing Callisto specific in the past,
Speaker 1: but most missions to or by Jupiter involves some level
Speaker 1: of callisto study. I mean, you're you're you're swinging by,
Speaker 1: it's in the neighborhood, it's one of the four largest moons.
Speaker 1: You're you're gonna get some data off of it. Now,
Speaker 1: I know we mentioned earlier the juice. The juice is
Speaker 1: thinking about studying icy moons of Jupiter and that would
Speaker 1: include Callisto right indeed, and then as far as considering
Speaker 1: any kind of far future visitation or specific study there,
Speaker 1: NASA's two thousand three Human Outer Space Exploration or HOPE
Speaker 1: project suggested that in a hypothetical five Jovian mission UH,
Speaker 1: Callisto could serve as a base of operations UH for
Speaker 1: study of Jupiter UH as well as other know outer
Speaker 1: Solar System concerns thanks to its stable geology and low
Speaker 1: radiation so again, nothing's changing their no earthquakes, there no volcanoes,
Speaker 1: and you're outside of that death zone for the most part.
Speaker 1: So it would be a great place to UH to
Speaker 1: UH to tell operate say a Europa submarine we're going
Speaker 1: to do rope in a little bit a little bit
Speaker 1: or or other gallee and noon explorations. It could also
Speaker 1: serve as a way station for outward bound vessels. I
Speaker 1: think that teleoperation idea is very interesting in the future
Speaker 1: of space exploration because one of the things you often
Speaker 1: run into and space exploration is well, Okay, when you've
Speaker 1: got a job that's very dangerous and and requires an
Speaker 1: extremely hardy explorer, you think, okay, we need a robot, right,
Speaker 1: But then when you've got a job that requires quick
Speaker 1: thinking and adaptability, you think you need a human explorer
Speaker 1: because I mean, a robot is not going to be
Speaker 1: able to figure out how to get around a problem
Speaker 1: very easily if you didn't anticipate it in advance. And
Speaker 1: a good way I've heard of of bridging this gap
Speaker 1: is having teleoperated robots. So instead of putting a human
Speaker 1: on the surface of Europa, you have a human in
Speaker 1: some nearby vessel, in a you know, spacecraft orbiting Europa
Speaker 1: or some or year by on Callisto maybe, and they
Speaker 1: are essentially by by avatar type of control making a
Speaker 1: robot do what it needs to do, but also being
Speaker 1: able to adapt to unexpected conditions and problems. So you
Speaker 1: send a robot to Europa, and you send maybe like
Speaker 1: a human brain and a scream canister to Callisto to
Speaker 1: remote control the robot in Europe. I feel like after
Speaker 1: reading about Callisto, though, I kind of felt bad for
Speaker 1: Callisto reading this proposal, because I'm like, you landed on Callisto.
Speaker 1: Callisto's cool, Callisto's fascinating. Don't get to Callisto and then
Speaker 1: dream of Europa. That's kind of inconsiderate. That's like, you're
Speaker 1: you're hanging out with this friend, don't text that one
Speaker 1: the other one during the hangout. But I mean, what
Speaker 1: if this other friend you're texting is just way more
Speaker 1: likely to have life on them. It's true, it's true. Okay,
Speaker 1: I think we're gonna take a break, but when we
Speaker 1: come back, we're going to get into the three inner
Speaker 1: Galilean moons where things really start to get interesting. Alright,
Speaker 1: we're back. We've left Callisto, We've left that dead, cratered
Speaker 1: world and it's a potential salt ocean hidden beneath its surface.
Speaker 1: What is our next destination in our journey? While our
Speaker 1: next destination isn't going to be all that different from
Speaker 1: Callisto in many respects. So we we left one cold, icy,
Speaker 1: rocky world and we're headed to another cold, icy, rocky world.
Speaker 1: But this one is Ganymede. Now, what the basic stats
Speaker 1: on Ganymy Ganymede is about in diameter about three thousand,
Speaker 1: two hundred and seventy three miles across or five thousand,
Speaker 1: two hundred and sixty eight kilometers. This makes it the
Speaker 1: largest moon in orbit around Jupiter, and not just there
Speaker 1: in fact, it's the largest moon in the entire Solar System.
Speaker 1: It's bigger than Pluto, bigger than the planet Mercury, but
Speaker 1: not nearly as massive due to low density composition. So
Speaker 1: you take an interior cross section of this planet, imagine
Speaker 1: you could sheer away half of it and look at
Speaker 1: an interior profile. You've got an iron core kind of
Speaker 1: like Earth has, but it's also possibly partially molten iron,
Speaker 1: and that's important for something I'm going to get to
Speaker 1: in a second. Then around that iron core you've got
Speaker 1: a layer of rocky inner mantle that's so like silicate
Speaker 1: rock standard rock, and then around that is a layer
Speaker 1: of water ice, probably also some salty liquid water. And
Speaker 1: then finally on top you've got an ice crust that
Speaker 1: shows signs of age, craters and scarring. So the molten
Speaker 1: metal in the iron core is probably why Ganymede has
Speaker 1: its own magneto sphere like Earth, and and the fact
Speaker 1: that it has its own magnetosphere is interesting. A lot
Speaker 1: of objects in the Solar System don't, but don't have
Speaker 1: a magnetic shield that extends outward from the planet, which
Speaker 1: makes possible visitation to those worlds all the more problematic.
Speaker 1: So I'm thinking this. I mean, we missed Colisto. This
Speaker 1: one sounds like a good place to touch down. What's
Speaker 1: it like on the surface. Okay, well, let's take a
Speaker 1: little tour of the surface of Ganymede. First of all,
Speaker 1: you're gonna notice as a thin oxygen atmosphere. But the
Speaker 1: emphasis is on thin. It's not thick enough that you
Speaker 1: could breathe it. But there is gonna be a little
Speaker 1: bit of gas around there. And imagine you step out
Speaker 1: of the spacecraft, say Anamde, so you're walking on ice.
Speaker 1: The crust of the planet is ice. It's this dark,
Speaker 1: endless plane of ice, possibly with some rocky elements here
Speaker 1: and there, but mostly it's going to be ice. It's
Speaker 1: like a frozen pond extending over the whole planet. So
Speaker 1: bring ice skates. Maybe, Actually I wonder, you know, if
Speaker 1: so ice is slippery here on Earth, is ice slippery
Speaker 1: on Ganymede. I have no idea why I would even
Speaker 1: wonder that. I would have to assume the physics are
Speaker 1: somewhat similar, but maybe not. I mean, it depends. Yeah,
Speaker 1: there's it's easy to take for granted something like ice skating,
Speaker 1: But ice skating it's going to depend on on what
Speaker 1: the gravity is like on the world, right, Yeah, yeah,
Speaker 1: gravity and the surface conditions. Now, one thing actually I
Speaker 1: think is that ice is less slippery the colder it
Speaker 1: gets outside, right, like an extremely cold conditions, You're less
Speaker 1: likely to slip on the ice. I feel like the
Speaker 1: novel that Forever War went into this a little bit.
Speaker 1: I believe like there's a section where he was getting
Speaker 1: into like the physics of being a visitor to an
Speaker 1: icy world and how slippery would be. But if then
Speaker 1: a long time since I've read that left up here
Speaker 1: from listeners, yeah, I would like to hear if you
Speaker 1: have ideas about that. But anyway, you're out on this
Speaker 1: ice crust, and one thing you can notice is that
Speaker 1: you can, as you travel the surface of Ganymede move
Speaker 1: from different kinds of landscapes into one another. So Ganymede
Speaker 1: has interlocking sections of an old face and a young face.
Speaker 1: Both are made of ice, but the old face is dark,
Speaker 1: covered in ancient craters from impacts over billions of years.
Speaker 1: It's what we talked about earlier. You know, the more
Speaker 1: craters you see on a surface, typically the older it
Speaker 1: is because it's been there to absorb blows from the
Speaker 1: shoe gallery of the Solar System for a longer period
Speaker 1: of time. Yeah, be aware of those planets where you
Speaker 1: don't see craters everywhere because something's happening there. Yeah. The
Speaker 1: craters on Ganymede I've read, are actually relatively smooth and gentle,
Speaker 1: and this possibly might be from millions of years of
Speaker 1: ice settling. So unlike rock where there's a crater, it's
Speaker 1: a brittle crater with edges, and it remains that way
Speaker 1: for a long time. With ice, over a long period
Speaker 1: of time, even though it's very cold, there is some
Speaker 1: kind of almost kind of gelatinous quality to the ice
Speaker 1: over long enough time scales so be kind of like
Speaker 1: an ice jelly. It's kind of like the way glaciers
Speaker 1: can deform over a long period of um. But then
Speaker 1: there's also a younger ice plaine on the surface of Ganymede,
Speaker 1: so you can move from one dark, scarred plane to
Speaker 1: another one, and these these younger ice planes are brighter
Speaker 1: in color, with fewer craters, and instead of craters, you'd
Speaker 1: walk through these deep wooves known as sulki. Each each
Speaker 1: of these it's a sulcus, is this groove running along
Speaker 1: the surface of the planet. It's like a wrinkle in
Speaker 1: the face of Ganymede, the sulci of Ganymede. I like it. Yeah,
Speaker 1: it's beautiful. And what are those caused by? Well, it's
Speaker 1: not exactly known, but I think the main idea I've
Speaker 1: read is that it's caused by internal stresses, entitled forces
Speaker 1: acting upon the planet, kind of causing wrinkles and perturbations
Speaker 1: in the crust. Okay, well, what are the natives like here? Well,
Speaker 1: if there are any, and there actually is a possibility,
Speaker 1: it's going to be kind of like what we talked
Speaker 1: about with callisso a similar kind of situations. Because findings
Speaker 1: announced by NASA and from the Hubble Space Telescope showed
Speaker 1: that Ganymede probably has liquid underground oceans sandwich between I
Speaker 1: see layers, And they figured this out by looking at
Speaker 1: at the aurora around Ganymede and figured out that you know,
Speaker 1: to see the to see the charged particle displays that
Speaker 1: we see around the outside of Ghanamy, we would probably
Speaker 1: be expected that we would probably expect that to be
Speaker 1: caused by liquid oceans under the surface. Uh, and anywhere
Speaker 1: of course that there's liquid water. We kind of have
Speaker 1: to wonder is there a possibility, And so that's the idea,
Speaker 1: and it's another case of subsurface liquid water that may
Speaker 1: indeed harbor microbial life. Now, past observations of Ganymede have
Speaker 1: been done by the some of the same missions we've
Speaker 1: talked about in the past, the usual suspects here, and
Speaker 1: of course Ganymede is one of the potential targets of
Speaker 1: Juice that the juice, so it's we mentioned earlier, but
Speaker 1: it's part of the Essays Cosmic Vision program. And the
Speaker 1: idea is that the probe would launch in two putting
Speaker 1: it on course to arrive in the Jupiter System around
Speaker 1: twenty and it would make observations of Jupiter itself but
Speaker 1: also Europa, Ganymede, and Callisto. And the main focus on
Speaker 1: Ganymede would be to learn more about its underground oceans
Speaker 1: and whether they have the potential to sustain life. But
Speaker 1: in addition to that, there are some Russian science tists
Speaker 1: who want to put a lander on Ganymede. Again, this
Speaker 1: would be to study potential habitable habitability. But this wouldn't
Speaker 1: just be a fly by. This would be a probe
Speaker 1: settling down on the surface and uh, and using various
Speaker 1: tools to figure out what's going on on the surface
Speaker 1: of Ganymede and and what might be going on under
Speaker 1: the surface. In indeed, that's a tantalizing part, right to
Speaker 1: to not only arrive there but too, but but to
Speaker 1: but to actually dig down into the surface and see
Speaker 1: if these oceans are really there and then what it
Speaker 1: consists up. Yeah, And of course Ganymede is not the
Speaker 1: only place where scientists want to drill under some ice
Speaker 1: and look at habitability concerns. In fact, there's an even
Speaker 1: better spot to study that, and it's the one that's
Speaker 1: coming up next on our death spiral into Jupiter. That's right,
Speaker 1: Europa in Europa is quite a big one in our
Speaker 1: in our consideration of Jovian moods. Yeah, if you read
Speaker 1: science fiction, I bet this is the most likely one
Speaker 1: you've read a story about. And it's often I would say,
Speaker 1: would you agree that of all the places in the
Speaker 1: Solar System, it's the one where astrobiologists most often talk
Speaker 1: about the possibility of finding life. Yes, this is definitely
Speaker 1: the one where where that has the most excitement around it.
Speaker 1: So Robert introduced us to this moon. We're coming up
Speaker 1: on now right. So while the surface of Europa appears
Speaker 1: to be a solid sheet of ice, scientists believe this
Speaker 1: outer shell hides a deep liquid ocean or an ocean
Speaker 1: of of ice slush underneath, the heated by tidal friction
Speaker 1: and thermal vents sixty two miles beneath Europa's ice caps.
Speaker 1: So Europa boasts a layered structure like Earth that consists
Speaker 1: of an iron core, a rock mantle around that core,
Speaker 1: a thick soft ice layer, and a thin crust of
Speaker 1: impure water ice over again what is probably a global
Speaker 1: subsurface water layer. Yeah, and so though Europa is a
Speaker 1: little bit smaller than Earth's moon, based on the Galileo data,
Speaker 1: you know, the data from the Galileta robe again not
Speaker 1: from Galileo galile uh, scientists think that Europa actually has
Speaker 1: more water on it than Earth does, which is pretty
Speaker 1: incredible because Earth is often known as the water planet.
Speaker 1: So if you you are the aliens from signs, it
Speaker 1: is even worse to try colonizing Europa than Earth. Now
Speaker 1: that ocean finding, as with Callisto's suspected subwa subsurface waters,
Speaker 1: come down to the Galileo spacecraft's measurements, specifically the manner
Speaker 1: in which Jupiter's magnetic field was disrupted in space around Europa.
Speaker 1: And the theory is that the field is induced by
Speaker 1: a large body of electrocly conductive salty fluid beneath the surface. Now,
Speaker 1: if we're to actually move in a little closer, if
Speaker 1: we were to touch down on Europa, what would we find. Well,
Speaker 1: the surface is apparently a vast landscape of frozen ice
Speaker 1: and it's criss crossed by long linear fractures and these
Speaker 1: are caused by tidal flexing, the tidal force caused by
Speaker 1: Jupiter's gravity. There are very few craters to be seen
Speaker 1: bloomishing this landscape, as as the surface is actually quite young,
Speaker 1: only for million years old, which is kind of creepy
Speaker 1: when you think about it. Yeah, this this ancient planet.
Speaker 1: We've never been there and it's got a young surface. Yeah,
Speaker 1: that's that's the first red red flag for any sci
Speaker 1: fi visitors. Right now. You'll also spot reddish brown materials
Speaker 1: and some of the fractures and splotchy deposits, and we're
Speaker 1: not yet sure what those are exactly. It might be
Speaker 1: magnesium sulfate, maybe sulfuric acid hydrate. You know, I think
Speaker 1: I've read that recent research suggested that the dark discolorations
Speaker 1: on Europea's ice crust could be caused by sea salt,
Speaker 1: supposed to radiation. Yet another piece of evidence that the
Speaker 1: water below the ice crust might be salty. Well, there
Speaker 1: you go. Now you'll also come across pits and domes
Speaker 1: in the ice that suggest that it could be slowly
Speaker 1: turning over or convecting due to heat from the possible
Speaker 1: oceans below. Or maybe they're just the dome cathedrals and
Speaker 1: fighting pit of some weird off world elder species right now. Now, wait,
Speaker 1: a second heat coming from the oceans below. Now that's interesting. Yeah, yeah,
Speaker 1: that's because if there's heat, that's one more possibly. Not
Speaker 1: only do we have a salty ocean, but there's there's heat,
Speaker 1: there's energy their energy rich, yeah, energy rich, more potential
Speaker 1: for life. Now there's also the chaos terrain. This is
Speaker 1: one of my favorite terms in astronomy. Is it astronomy,
Speaker 1: I don't know, astrogeology, planetology, Yeah, I guess so. Yeah,
Speaker 1: the chaos terrain. This is a broken, blocky landscape covered
Speaker 1: in the mysterious reddish material that we mentioned earlier. So
Speaker 1: it might be spots of geogeologic activity. It might be
Speaker 1: places where the ice has collapsed into lakes in the ice.
Speaker 1: And it's also possible that we're just merely over interpreting
Speaker 1: h imperfections in the Galileo spacecraft imagery. Oh yes, and
Speaker 1: is revealed in the in two thousand thirteen Hubble telescope data.
Speaker 1: Europa is actively venting plumes of water into space. So
Speaker 1: this means that it is definitely geologically active. So it's
Speaker 1: like geyser is shooting off of the Yeah. Yeah, So
Speaker 1: so we've got that to think of two, like space
Speaker 1: geysers shooting water into space. So does it have an
Speaker 1: atmosphere at all? It does. It has a molecular oxygen
Speaker 1: and O two atmosphere. Hydrogen floats away from the planet
Speaker 1: because it's too light and collects in a gas torus
Speaker 1: around the planet. Less impressive than than the one on
Speaker 1: Io that will discuss, but still pretty pretty interesting nonetheless.
Speaker 1: And as far as size goes for your Europa, it's
Speaker 1: slightly smaller than Earth's moons. So Europa is the smallest
Speaker 1: of the four Gallean moons. Yes, but size doesn't necessarily
Speaker 1: matter when it comes to subsurface life, that's right, So
Speaker 1: if Europa's oceans do exist, and we're pretty sure they do,
Speaker 1: it's I think most scientists agree that's what's what's going
Speaker 1: on under there. Then the tides might also create volcanic
Speaker 1: or hydrothermal activity on the sea floor, supplying nutrients that
Speaker 1: could make the ocean sustainable for living things. Yeah. So
Speaker 1: often when you want to imagine what kind of alien
Speaker 1: life could exist on place, in places other than Earth,
Speaker 1: it's a good idea to look at extrema files on Earth.
Speaker 1: What exists in some of the most difficult conditions on Earth.
Speaker 1: And one of the things to look out on Earth
Speaker 1: might be the life that is sustained by hydrothermal vents
Speaker 1: on the ocean's floor. Yes, we're talking about deep, dark
Speaker 1: places where really the only font of energy is is
Speaker 1: the the the hydrothermal vent. But that is, you know,
Speaker 1: pumping out some very high temperatures in an otherwise cold
Speaker 1: and light lift environment. And uh, and there are there
Speaker 1: are organisms that have evolved to thrive in that environment.
Speaker 1: But look again, it's go back to what you said earlier.
Speaker 1: We call them extreme of files. But of course, if
Speaker 1: that were the only place life could exist on a world,
Speaker 1: would they really be extreme of aisles. It kind of
Speaker 1: depends on how you know where you're approaching it from it. Yeah,
Speaker 1: that's what they're adapted to. Yeah, I mean, try to
Speaker 1: put them in a in a lush farm land on
Speaker 1: Earth and then you would die out. That would be
Speaker 1: their extreme environment. Yeah. So there's a lot of a
Speaker 1: lot of hope, a lot of excitement, uh, specifically for
Speaker 1: Europa because a number of the factors UH in the
Speaker 1: or in the emergence of life seemed to exist there. Yeah,
Speaker 1: and because of that, Europa is a prime target for
Speaker 1: future exploration and research. So we've mentioned Juice. Juice wants
Speaker 1: to go to Europa, of course, but what else is
Speaker 1: going to Europa? Well, NASA is currently putting together the
Speaker 1: Europa Multiple fly By mission for the same time period.
Speaker 1: That mission is scheduled launch in arriving at the Jovian
Speaker 1: System in two seems to be a big year in general.
Speaker 1: According to a BBC report from actually earlier this month,
Speaker 1: NASA is eyeing that year as a potential launch date
Speaker 1: for a soft landing mission to Europa. All so es
Speaker 1: A scientists are currently considering these five different concepts um
Speaker 1: for their own explorations So one is a remote sensing
Speaker 1: instrument that would go aboard that that American two probe.
Speaker 1: Another is a small free flying satellite that would detach
Speaker 1: from this probe. Another is a small satellite that would
Speaker 1: detach from the lander's mother ship. Another is one or
Speaker 1: two instrumented projectiles that would drop from the mother ship projectiles. Yeah,
Speaker 1: and we'll we'll get to to the projectile aspect here
Speaker 1: in a second. Also an instrument to ride on the
Speaker 1: soft lander and uh quote unquote do science at the surface. Um.
Speaker 1: I love it when landers do science. Yeah, I mean
Speaker 1: it's one of those things where it's you know that
Speaker 1: we're in the early enough stages for figuring out exactly
Speaker 1: what it would do, but then we also know a
Speaker 1: number of the science that it would do. But then
Speaker 1: the one that really is fascinating is the idea of
Speaker 1: a penetrator hard Lander. So this would a steel missile
Speaker 1: loaded with sensors that strikes at three hundred miles per
Speaker 1: second and collects data on the interior. So we're talking
Speaker 1: some very rugged instruments. They've apparently tested this out a
Speaker 1: little bit on Earth, uh and found that, yes, that
Speaker 1: the instruments do survive such an impact. Well, that's one
Speaker 1: of the interesting questions is what we would do to
Speaker 1: get to that subsurface ocean, because so you'd have to
Speaker 1: if you land on the surface of Europa, if you
Speaker 1: imagine it has an extremely thick ice crust and the
Speaker 1: subsurface ocean is underneath that, you'd have to drill down
Speaker 1: or melt down to get to it. And then once
Speaker 1: you're down there, how do you get the data back
Speaker 1: up to the surface. Right, And and we don't want
Speaker 1: to discount just the journey to any of these moons
Speaker 1: in general, because this is not like the friendliest neighborhood
Speaker 1: to enter into your kind of entering. As we mentioned,
Speaker 1: you're kind of going into a sub solar system with
Speaker 1: plenty of objects singing around with rings, etcetera. So it's, uh,
Speaker 1: there are a number of factors that there are a
Speaker 1: number of hurdles to even getting to your destination. Now, Robert,
Speaker 1: have you seen the science fiction movie Europa Report. I
Speaker 1: have not. I really liked Europa Report. I I would
Speaker 1: be interested in hearing what you guys out there think,
Speaker 1: our listeners. Have you seen this movie? I thought it
Speaker 1: was cool and that it was a modest science fiction
Speaker 1: movie that did it did a lot with a little
Speaker 1: and one thing I really liked about it is that
Speaker 1: it was truly a science fiction movie about the exploration
Speaker 1: of Europa and science fiction, I mean, um, a lot
Speaker 1: of movies that are called science fiction are really just
Speaker 1: sort of action fantasy where the instead of having magical weapons,
Speaker 1: you have technological weapons, but they're still basically the same
Speaker 1: the viewer that has no idea what it's just. Instead
Speaker 1: of having a religious or supernatural explanation for the magic,
Speaker 1: it is a vaguely science explanation for them magic. Yeah, exactly.
Speaker 1: And this movie was not like that. I mean that
Speaker 1: it was a science fiction movie in that the plot
Speaker 1: was inherently about science. It had a it has scientific
Speaker 1: plot and the scientific thrust, and the characters had a
Speaker 1: scientific mission that was actually grounded in real things we'd
Speaker 1: want to learn in the real ways we'd go about
Speaker 1: trying to learn them. Uh. And so I won't I
Speaker 1: will try not spoil anything about the movie, but they
Speaker 1: it's a movie about a manned mission, or I should
Speaker 1: say a crude mission, a mission with a crew going
Speaker 1: to the surface of Europa and trying to figure out
Speaker 1: if there's life in the oceans underneath and so I
Speaker 1: give it a thumbs up. Does hilarityst No, not really
Speaker 1: hilarity maybe some I, without spoiling too much, I will
Speaker 1: say that things don't go exactly to plan. Did it
Speaker 1: wouldn't be much of a movie, all right. Well, at
Speaker 1: this point, let us sadly leave Europa with its mysteries unsolved,
Speaker 1: and continue on to the innermost of the Galilean moons. Yes,
Speaker 1: now does time. We're approaching Io. It's spelled two letters io,
Speaker 1: and that seems to make sense. But because there's a
Speaker 1: kind of grinding simplicity and beauty and weirdness to this planet,
Speaker 1: it's it's it's maybe the strangest and most gorgeous of
Speaker 1: all of them, and of all of them it most
Speaker 1: wants to kill you. So IOW is Jupiter's innermost Galileean moon.
Speaker 1: In terms of diameter, it is slightly, but only slightly
Speaker 1: larger than Earth's moon. It's almost comparable in size, and
Speaker 1: its orbit keeps it within four hundred and two kilometers
Speaker 1: or two hundred sixty two thous miles of Jupiter. That's
Speaker 1: not not a whole lot farther than the distance between
Speaker 1: the Earth and its moon, except think about how big
Speaker 1: Jupiter is yeah. Yeah, so what's yeah, So what's like
Speaker 1: on the surface of Io. It's freezing hell and burning
Speaker 1: hell at the same time, where the ground that you
Speaker 1: walk on churns up and down like a tsunami as
Speaker 1: the tides go in and out. On the solid world.
Speaker 1: Io is a world of extremes. It's uh. It's the
Speaker 1: most geologically active object in the Solar System, the whole
Speaker 1: Solar System, including Earth, with more than four hundred active
Speaker 1: volcanoes that we know about some eruptions. These volcanoes shoot
Speaker 1: ejective plumes of three hundred kilometers or a hundred and
Speaker 1: eighty six miles out into space above the surface. If
Speaker 1: you see some images of these, it's incredible. It looks
Speaker 1: like it looks like there's something else going on behind
Speaker 1: Io that's being obscured by the planet. But no, you
Speaker 1: that's not what it is. You're just seeing in profile
Speaker 1: plumes of planet sized proportions exploding off of the surface.
Speaker 1: And uh. And so the average temperature on the surface
Speaker 1: is negative two hundred and two degrees fahrenheit or negative
Speaker 1: a hundred and thirty degrees celsius, which is far colder
Speaker 1: than the coldest natural temperature ever recorded on Earth, that is,
Speaker 1: unless you're standing near one of Io's hundreds of volcanoes
Speaker 1: while it's erupting, and here the temperatures are more like
Speaker 1: three thousand degrees fahrenheit or D one thousand sixty nine
Speaker 1: degrees celsius. There is an atmosphere, but it's thin and
Speaker 1: mostly made of the toxic gas sulfur dioxide, which is
Speaker 1: often associated with volcanic activity even on Earth. So if
Speaker 1: you know, you get killed by toxic fumes near a
Speaker 1: volcano or something like that, you may be breathing sulfur dioxide.
Speaker 1: And speaking of sulfur compounds, the planet is also going
Speaker 1: to be covered probably in fields of yellow snow. You
Speaker 1: don't eat the yellow snow in this case, and it's
Speaker 1: because it's sulfur dioxide snow. So the planet it has
Speaker 1: these eruptions where these particles of sulfur dioxide gas come
Speaker 1: out and go all around the planet. But then because
Speaker 1: it's so cold, they tend to crystallize and fall down
Speaker 1: as the sulfur dioxide yellow snow. Uh, So it's just
Speaker 1: covered in these poisonous golden snow fields. But other than that,
Speaker 1: it's a good place to visit. No, no, it's also
Speaker 1: a blasted heath of radiation. So uh, it's the closest
Speaker 1: to Jupiter and the most exposed to Jupiter's radiation. And
Speaker 1: then there's also because Io is connected to Jupiter through
Speaker 1: a sort of magnetic ring that comes out of Jupiter's magnetosphere,
Speaker 1: it also creates what's called a plasma torus, which is
Speaker 1: just this ring of killer charged particles flowing off of
Speaker 1: Io and into Jupiter. Uh. And it's it's kind of unbelievable.
Speaker 1: You you wouldn't want to get near it, you wouldn't
Speaker 1: want to stand in it. You really don't even want
Speaker 1: to fly a probe through it. And I mentioned earlier
Speaker 1: the tidal heaving on Io. So on Io, there there
Speaker 1: are tides, but there are no oceans. It doesn't have
Speaker 1: water to have tides. It has tides in the ground itself.
Speaker 1: Now other planets well too, tides of course, you know,
Speaker 1: being influenced by the gravity of surrounding bodies. There's there's
Speaker 1: tidal action acting on Io from Jupiter and from the
Speaker 1: other moons that are going around Jupiter. But these incredibly
Speaker 1: powerful gravitational forces, instead of moving water around on the surface,
Speaker 1: end up moving the ground up and down hundreds of feet. Now,
Speaker 1: from what I understand, I think you wouldn't feel this
Speaker 1: like you know, waves coming up and down really fast
Speaker 1: or anything like that. But it does. This tidle flexing
Speaker 1: and stretching of the solid mass of the planet does
Speaker 1: lead to incredible friction. I mean, think what would happen
Speaker 1: if you were constantly flexing a rock in and out
Speaker 1: to get pretty hot, And this is what happens to
Speaker 1: the interior of Io, leading it to be this burning
Speaker 1: hellscape within the freezing hellscape. Another crazy fact about Io
Speaker 1: Jupiter is going to loom huge in the sky. The
Speaker 1: NASA JPL website has a really interesting app that I
Speaker 1: recommend you try to use it. It's the Solar System Simulator,
Speaker 1: which lets you simulate looking at one object in the
Speaker 1: Solar System from another object in the Solar System at
Speaker 1: any given time. Uh. And I tried this out. I
Speaker 1: was like, Okay, what does it look like looking at
Speaker 1: Jupiter from Io right now? And from the surface of
Speaker 1: Io right now? Jupiter currently takes about it takes up
Speaker 1: about nineteen point five degrees in the sky, so you know,
Speaker 1: imagine the degrees from horizon to horizon you've got about
Speaker 1: a hundred and eighty degrees. Uh this so this is
Speaker 1: about twenty degrees. That's like one ninth of the width
Speaker 1: of the sky. It's crazy to imagine that. I mean,
Speaker 1: it's it's crazy to imagine even of course, standing on
Speaker 1: the surface of Io and you're I guess godlikes space
Speaker 1: suit that somehow protects you from all of these extreme conditions. Somehow,
Speaker 1: I think we're not ever going to be walking on
Speaker 1: I yeah, I mean you would have to be dealing
Speaker 1: with like a what like a level level one or
Speaker 1: level two civilization just kardashi yea Cardachan level, like some
Speaker 1: sort of like crazy sci fi field system like where
Speaker 1: it wouldn't even be a physical suit as much as
Speaker 1: like a crazy energy shield that is somehow protecting you
Speaker 1: unless you're Sean Connery with a shotgun. Right. Oh? Yes, Um,
Speaker 1: is it too early to mention Outland? No, it's not so.
Speaker 1: Before we recorded the episode, we were talking about how
Speaker 1: Robert just rediscovered that the movie Outland, the starring Sean Connery,
Speaker 1: which is essentially high Noon in space. Yeah, it's a
Speaker 1: space western, Uh, nice and gritty. It's it feels like
Speaker 1: you could take place in the same universe as Alien US,
Speaker 1: you know, a lesser film, but it has that kind
Speaker 1: of grimy uh you know Workman's vision of life in
Speaker 1: the solar the opposite of Flash Gordon. But it takes
Speaker 1: place us on Io right again, How realistic is that?
Speaker 1: Seems not very Yeah, it's been a while since I've
Speaker 1: seen it, but I do not recall the I do
Speaker 1: not recall any highly volcanic scenes. I could be wrong
Speaker 1: on that. I felt feel like they delivered like a
Speaker 1: cold or vision of Io. Yeah, but it's it's a
Speaker 1: great film, very violent, a very very gritty space drugs,
Speaker 1: space prostitutes, Sean Connie with a shotgun, Peter Boyle and
Speaker 1: some other actors that would go on to to make
Speaker 1: a name for themselves, and then the cast as well.
Speaker 1: Is it kind of like Leviathan in Space? Not really,
Speaker 1: there's no monster. It's like it's a very human story.
Speaker 1: It's it's essentially you know, it's it's a mining town
Speaker 1: Western scenario. But on this Jovian, I guess I was
Speaker 1: just going with the mining outpost aspect of Leviathan. Um,
Speaker 1: do we need to talk about Leviathan on this podcast?
Speaker 1: We can carry on. Sorry, I've seen that one more recently. Yeah,
Speaker 1: well it does have a great poster. It does fabulous poster. Okay,
Speaker 1: So back to Io. Given everything we've said so far
Speaker 1: freezing hell and burning hell, uh, sulfur dioxide, vicious radiation bath,
Speaker 1: we shouldn't expect this place to have any life at all, right,
Speaker 1: it seems a ridiculous proposition. Also, no liquid water on
Speaker 1: the surface. It sounds like the last place. No organic
Speaker 1: molecules ever detected there, I mean, why ferocious radiation, so
Speaker 1: we can definitely rule out the possibility right, Well, actually
Speaker 1: not according to everyone. And I wonder if this is
Speaker 1: just an expert uh an astrobiologists trying to emphasize what
Speaker 1: possibilities are out there, more thought experiment than anything it
Speaker 1: could be. But from two thousand ten, I found an
Speaker 1: article by Charles Q. Choi that speaks to Dr Dirk
Speaker 1: Schultz may COOCHU an astro biole an astrobiologist at Washington
Speaker 1: State University, and UH. Dr Schultz may Cooch said, quote,
Speaker 1: life on the surface is all but impossible, but if
Speaker 1: you go down further into the rocks, it could be intriguing.
Speaker 1: We shouldn't categorize it as dead, right, away just because
Speaker 1: it's so extreme. So, based on this guy's comments, this
Speaker 1: astrobiologist comments, the article went on to sort of explore
Speaker 1: what life could be like on Io. You know, if
Speaker 1: we if we look at Europa and Ganymede, which have
Speaker 1: water ice, we can get a picture closer to what
Speaker 1: Io might have looked like billions of years ago, closer
Speaker 1: to the time of its formation. Radiation from Jupiter probably
Speaker 1: would have ripped away Io's water within about ten million
Speaker 1: years or so, but life that evolved on the surface
Speaker 1: during that period could possibly have retreated underground, surviving in
Speaker 1: subterranean lava tubes, which could contain moisture and protect the
Speaker 1: microbial life forms from radiation that's on Io's surface. What
Speaker 1: what is impossible up above may not be impossible below.
Speaker 1: And as we've pointed out before, they're extreme a file
Speaker 1: organisms on Earth that can survive and thrive in lava
Speaker 1: tubes and even near active geotherm hotspots like Geyser's. So
Speaker 1: Schultz make Coach comments that the ultimate chances of finding
Speaker 1: life on Io seem pretty low, but we shouldn't rule
Speaker 1: it out. And besides, how amazing would that be to
Speaker 1: find life on this sulfurous golden hell. It would really
Speaker 1: change your idea of what's possible for self replicating organisms
Speaker 1: in the universe, I think indeed, you know, and it
Speaker 1: also makes me wander you know, we've we've been discussing
Speaker 1: some sci fi a little bit here, but you're always
Speaker 1: encountering that idea of of of either a human or
Speaker 1: other intelligence civilization seating life in other worlds. And generally
Speaker 1: that doesn't take the forum of extreme of files. But
Speaker 1: but I wonder, like, what could we one day reach
Speaker 1: the point where a human or human derived civilization would
Speaker 1: reach a world like like Io. Look at it determined
Speaker 1: that there's no even there's no life, even extreme a
Speaker 1: file life. But then custom makes something to survive, and
Speaker 1: it's like it's in its most tolerable, um A location.
Speaker 1: I don't know, it's fun to think about. Yeah, well there,
Speaker 1: I mean, I think you get into, of course, the
Speaker 1: the ethics questions about seeding life. You know, you'd have
Speaker 1: to be sure if that's even possible that there was
Speaker 1: no life there now and that life wasn't you know,
Speaker 1: in store for it at some point in the future.
Speaker 1: Um So, who's to say? But then again, I think
Speaker 1: that's kind of weird, like I feel this ethical intuition
Speaker 1: that you shouldn't go about, you know, contaminating other worlds
Speaker 1: with possible life that could extinguish the life that exists
Speaker 1: there now. But then again, I really don't feel bad
Speaker 1: about using alcohol to kill bacteria. If you're washing your
Speaker 1: hands before surgery or something like that, you know, it's
Speaker 1: I don't know, well, you know that bacteria was never
Speaker 1: going to make it to Aisle anyway, so it's fine.
Speaker 1: I guess so alien bacteria just has so many more
Speaker 1: rights than Earth bacteria. Okay, So future missions to Io
Speaker 1: one would be the Io volcano observed over one proposed
Speaker 1: future mission at least we don't know, but uh, the
Speaker 1: proposed future mission to Io would be this observer, primarily
Speaker 1: the work of the planetary geologist Alfred McEwan, And this
Speaker 1: would be a probe that goes into orbit around Jupiter
Speaker 1: and observes Io close up over the course of at
Speaker 1: least nine flyby's over two years. And this would be
Speaker 1: studying Io's temperature, it's a volcanic activity and its surface composition.
Speaker 1: And if the proposed mission is accepted, it's going to
Speaker 1: launch by around one So it seems like in the
Speaker 1: early twenties, there's going to be a lot of potential
Speaker 1: Jupiter missions launching. That has got to be a I mean,
Speaker 1: we've already discussed the volcanic eruptions that blast out into
Speaker 1: into space off of Io, so that would see, it
Speaker 1: would seem like it would be a difficult orbit to maintain,
Speaker 1: and maybe that's part of the gamble, like how well
Speaker 1: I mean, I guess the question would be exactly how
Speaker 1: close is it getting to Io if it's gonna be
Speaker 1: orbiting Jupiter. Uh. I think I read something like that
Speaker 1: the closest point it would ever get to Io would
Speaker 1: be around two hundred kilometers away, which is I mean,
Speaker 1: that's pretty past. But the bigger question, I think, much
Speaker 1: more than the geologic activity, is just the radiation. I mean,
Speaker 1: even even non organic just our instruments at that point
Speaker 1: are can be subject to extreme radiation and so it
Speaker 1: would have to be a hardy kind of probe to survive.
Speaker 1: If anything were to actually land on Io, it would
Speaker 1: have to be a flying fallout shelter. As we've mentioned,
Speaker 1: the radiations fierce, and it has damaged instruments on probes
Speaker 1: in the past, right, Yes, I mean that's how that's
Speaker 1: how potent the radiation of IO is. One last thing
Speaker 1: I wanted to add about IO coming from the angle
Speaker 1: of exo theology. Uh, the religion space religion. Oh, this
Speaker 1: is a this is a topic I love. Yeah, of
Speaker 1: course I love it too. And uh, we should add
Speaker 1: that we keep using the Hell analogy for I just
Speaker 1: merely for descriptive reasons, to give you an image to
Speaker 1: map it onto in your brain. But there's actually at
Speaker 1: least one theologian who exists who believes Hell can be
Speaker 1: found in the Solar system. Uh. He is a guy
Speaker 1: named Michael sin teeny and he's a reverend who he
Speaker 1: self published a book that argues that the Christian Hell
Speaker 1: is literally to be found on the planet Venus. And
Speaker 1: I don't know how many people he's managed to convince
Speaker 1: of this. This is obviously not a standard Christian belief.
Speaker 1: This is his idea. Um, but I wonder why not
Speaker 1: Io instead? I know, seems like an even better candidate. Yeah,
Speaker 1: I mean, you have it. Fl It flows perfectly with
Speaker 1: Dante's vision, right because you have both the hot region,
Speaker 1: the hot regions, the cold regions. It's it's perfect. All
Speaker 1: you need is Satan there after his waist. And yeah,
Speaker 1: and it matches with our journey of descent, right as
Speaker 1: we've gone closer and closer into the planet. Which reminds me,
Speaker 1: now that we've reached the end of our journey, we're
Speaker 1: getting very close to Jupiter itself. Yeah, and our our
Speaker 1: little terrarium capsule is withering a little bit. It was
Speaker 1: standing the inner radiation of the Jovian System. I wonder
Speaker 1: what's going to happen as we descend into the gas.
Speaker 1: I don't know. We're descending into a into a massive
Speaker 1: gas world of storms and poison and uh and eventually
Speaker 1: a Rocky core. Uh. With the pressure and the it's
Speaker 1: just insane. I'm pretty sure we'll be obliterated before we
Speaker 1: reach the Rocky Cory. Oh yes, yes, certainly. I doubt
Speaker 1: we'll love to reach the Rocky Corps. But maybe there
Speaker 1: is no Rocky Core. Maybe the Rocky Core is all
Speaker 1: in your mind. Well, the important thing is that we
Speaker 1: made it this far. I mean, we were ordered to
Speaker 1: jettison the dome a while back. We held on this long.
Speaker 1: Everything got to survive there just a little bit longer,
Speaker 1: so we can we can play one last game of
Speaker 1: checkers or cards with the robots and just go out
Speaker 1: on a high note. Well. One thing I should have
Speaker 1: mentioned you as we were going, but I didn't because
Speaker 1: I was afraid was that at each moon we passed
Speaker 1: along the way, I jettisoned all a capsule of Earth life,
Speaker 1: unethically seating these planets and potentially contaminating them for all
Speaker 1: future research. But maybe these little life forms will take hold. Yeah. Well, hey,
Speaker 1: that's better than nothing, right, So let's hope something takes root,
Speaker 1: all right. So there you have it, an exploration of
Speaker 1: the Galilean moons, just the four greatest of the Jovian
Speaker 1: moons in general, but each one a fascinating world. And
Speaker 1: uh and the cool thing too, is that even over
Speaker 1: the course of the next year or so, we're hopefully
Speaker 1: going to learn more and more about these these places. Yeah,
Speaker 1: so we want to thank you for joining us on
Speaker 1: our journey through this solar system. Within a solar system,
Speaker 1: the the gas Giant and it's wonderful sphere of influence. Indeed,
Speaker 1: and if you want to see images of some of
Speaker 1: these moons as well as explore some links out to
Speaker 1: additional data about them, be sure to check out the
Speaker 1: landing page for this episode. At stuff to blow your
Speaker 1: Mind dot com. That's the mothership. That's where we will
Speaker 1: find all the podcast episodes. You'll find blog posts, you'll
Speaker 1: find galleries, lists, videos, links out to our social media
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Speaker 1: on both of those. We also have Tumbler and Instagram accounts.
Speaker 1: If that is your jam, and if you want to
Speaker 1: get in touch with us with your favorite fact about
Speaker 1: Jupiter or its moons, or you want to let us
Speaker 1: know what you think the most interesting object in the
Speaker 1: Solar System is, or where you think we're most likely
Speaker 1: to find the life outside of Earth, you can email
Speaker 1: us at blow the Mind at how stuff works dot com.
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