Jupiter's Children: A Voyage to the Galilean Moons

Of all the moons of Jupiter, Callisto, Ganymede, Europa and Io tantalize us the most. These alien worlds of ice, fire, desolation and hidden oceans tantalize us with their possibility for extraterrestrial life and human exploration of the outer solar system. Join Robert and Joe for a mind bending exploration of the great gas giant's Galilean Moons.

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Episode Transcript

Speaker 1 (00:03):
Welcome to stuff to blow your mind from House that
Works dot com. It really is darker out here in
the outer Solar System. Your space freighters one remaining forest

(00:24):
dome struggles but barely scrapes along, surviving the plants still
put out leaves. It seems only yesterday that you defied
orders to jettison the dome and return to Earth immediately,
But instead you absconded. You took the plant life capsule,
and you flew away away from the Sun, out into

(00:49):
the outer Solar System. You have only the forest and
a pair of robots now to accompany you through this
long twilight. You'd hope to pass beyond Jupiter and find
refuge within the rings of Saturn, But the great gas
giant will not be defied. It's massive gravity tugs at
your humble freighter. The red eye of its century spanning

(01:10):
storm taunts you as Jupiter drags you into the orbital
realm of its many moons. But still there's hope. Perhaps
one of the four greater moons, the Galilean moons, will
offer some place of refuge. But which of these strange
and hostile worlds might serve as a new home for you?

(01:31):
And this geodesic refugium from old Earth's lost biodiversity. Hey,
you're welcome to stuff to blow your mind. My name
is Robert lamp and I'm Joe McCormick. And you should
imagine yourself in the scenario we just described. You're in
some kind of spacecraft, hopefully one that has some some

(01:51):
plants along with it to keep you sustained through the
long Outer Solar System journey and no hostiles, in a
morp onboard exactly. Uh, And you are caught in the
gravitational influence of the planet Jupiter. You didn't mean to
end up this way, but hey, you know, Jupiter's gravity
is something that's difficult to escape. And now now you're

(02:12):
stuck spiraling in towards Jupiter, slowly decaying in your orbit,
getting closer and closer all the time. But one thing
you have noticed is that you will get to see
a close up view and perhaps, if you're lucky enough,
maybe land on Jupiter's four largest moons, known as the
Galilean moons. This is the tour we want to take

(02:35):
you on today. Indeed, these moons are of course of
immense interest to science. Now, one analogy that I think
is interesting to help us understand the way the Jupiter
system and its gravitational influence works is to think of
Jupiter kind of like a star within our solar system,

(02:55):
like it's its own star, and the planet, the moons
that are going around Jupiter kind of like planets orbiting
this solar system within a solar system. Indeed, because it
is a massive planet, it's mass is three hundred and
seventeen point eight to eight uh times that of Earth,

(03:15):
and uh, it's of course a gas giant. It's mostly gas,
but it might have a solid core about the size
of Earth at the center, possibly a rocky ice covered core,
within sane levels of atmospheric pressure and temperatures hotter than
the surface of the Sun. And Jupiter features no fewer
than sixty seven lunar objects. That includes fifty confirmed moons

(03:41):
and seventeen unconfirmed or provisional moons. And these are the
ones we know about. Yeah, but yeah, and they've got
cool names like Metis and and Drastia. And then of
course there's also the There are also three faint gossamer
rings around Jupiter as well, certainly not as robust as
the Saturn's rings, but they're there. Nonetheless, so we should

(04:01):
back up and start at the beginning, because we're learning
a whole lot more about Jupiter's moons, especially at Jupiter's
Galilean moons, the ones we're going to focus on today,
the four largest moons. But we were learning a lot
more about that recently. But we've known about Jupiter since
ancient times because you don't need a telescope to see Jupiter.

(04:22):
That's right, it's visible from Earth, and so it factors
into many ancient systems of astrology and by virtue virtue
of that cosmology. The Roman name Jupiter stems from the
king of the gods, but the planet that plays a
role in many cultural beliefs. In Chinese astrology. For instance,
it's the character of Fu uh character of foods tied
to Jupiter, and he's the who is Fu. He's the

(04:43):
embodiment of good fortune uh symbolized in a scholar's dress,
and he's cradling a child. The three stars that you
often see. You often see these three statues of these
men in Chinese households, Chinese businesses UH. And they each
kind of they each represent a different form m of
of idealized to success. The one is old and wise,

(05:04):
one and one is a successful with his family and
the other one is successful with business. I always think
it's interesting that we see this cross cultural phenomenon of
associating planetary bodies or objects in the sky with God's Yeah,
it's fascinating because you see this in other systems as well.
For instance, the Vedic astrology, Jupiter is everything from the

(05:24):
dwarf incarnation of Vishnu to to Ganesha or sometimes Brahma.
So it it varies with within that system. But yeah,
that Jupiter always seems to have a pretty cushy role
within a given a given cultures astrology. Yeah. So we
mentioned that ancient cultures knew about Jupiter because you can
see it with the naked eye, But one of the
things they didn't know was much more about Jupiter other

(05:48):
than it being a point of light. That's right. For instance,
when we think of Jupiter, what what do we in picture?
We picture that big, big gas giant with a big
red eye, right, red spot, Yeah, the giant red hurricane
on Jupiter's outer surface. Yeah, it's great to focus in
on on the red storm because it helps us really
understand Jupiter and our relationship to Jupiter, because, for one,

(06:10):
On one hand, that storm has not been there forever, uh,
and it will not be there forever, but it spans centuries.
It's been there as long as we've been able to
see Jupiter in that kind of detail. Uh. And it
in the storm itself is two to three times the
size of Earth. Uh. So that helps put again the
massive scale of Jupiter. Can you imagine if on Earth

(06:31):
we had storms that lasted for I don't know, hundreds
of years. I've I've thought about it, like when you
start teasing apart our weather system and you start looking
at the different the different systems involved there, and the
different factors that end up decreasing a hurricane's power. You know,
what if those were not there? What if you had
a scenario where the storm was essentially just a permanent

(06:54):
part of the planet as a mortal individual would experience it.
You know, that would be a great setup for like
a sci fi thriller. Imagine the weather conditions on Earth
change that such that tornadoes tend not to dissipate on
their own unless you have to. You have to find
a way to essentially dissipate tornadoes by force. Yeah. Indeed,

(07:15):
and that red storm on Jupiter is dissipating slowly, but
it's still there as of this recording. Now, as far
as how far away Jupiter is, it's fo four million
miles seven million kilometers or five point two astronomical units
uh from the planet Earth. Okay, so we know Jupiter
is a gas giant. But you always wonder what's inside

(07:38):
a gas giant. I mean, is it all just gas
or is there something solid inside there? Well, we don't
know for certain. We uh, the atmosphere of Jupiter's mostly
hydrogen and helium, but it might have a solid core
about the size of Earth. And this might be an
icy covered core with just really insane levels of atmospheric pressure.

(08:00):
An temperature is hotter than the surface of the Sun.
So it's very much the core and not you know,
not the surface of the planet. But but you know,
you can't help it. Imagine, well, what if what if
you could what if you could transport yourself down to
the physical surface of this gas world. It would of
course be just unimaginable with one of the most hostile

(08:23):
environments you could even envision in the Solar System. Yeah,
it's pretty rough and one of the things that's going
to come up repeatedly. I think today is how Jupiter,
though it may look very serene and beautiful to us,
is it kind of meets that analogy I worked out
at the beginning about it being like a star, because

(08:44):
Jupiter is it has massive gravitational influence. It's very electrically active,
and it's just it's just full of radiation. You don't
want to go near Jupiter, right, Yeah. Yeah, to be
sucked into Jupiter would be to be sucked into death, really,
and that's one of the things we're out lying in

(09:04):
the intra material. Yeah, so it's really unfortunate that we're
slowly spiraling into Jupiter in today's thought experiment. But but
we we should at least take the time to appreciate
the sites we'll see along the way. That's right, and
uh and and maybe if we're lucky, grasp onto them
and uh and seek refuge a refuge upon them, because
even though they are all very hostile worlds in their

(09:26):
own right, there's still a better bargain and they still
present a better chance for not only the potential like
the real life potential for for human visitation. But in
some of these cases we'll discuss the possibility for extraterrestrial life. Yeah, okay, Now,
Jupiter is not entirely unexplored today. We've actually sent quite

(09:46):
a few probes Jupiter's way that have that have orbited
Jupiter and made various observations about it and it's major satellites, right,
that's right. To date, NASA has sent nine space missions
to or by the gas. So we're talking the Pioneer
program seventy four, the Voyager program seventy nine, Ulysses and Cassini,

(10:08):
and two thousand new horizons in two thousand seven. Also,
Galileo is a big one, and that's a two thousand
three Juno. That one's of course a very current that's
two thousand sixteen. And there are various additional missions and
schemes for missions in the works. Oh yeah, I know.

(10:29):
The E. S A is working on the Juice Explorer, right,
the Jupiter Icy Moon Explorer, which I don't know. I
don't know if I agree with the wisdom of calling
it Juice. It seems just a little too cool, like
like it's like the name doesn't need to be that
cool because it's going to Jupiter. You know, it's going

(10:50):
to the moons of Jupiter. That alone is is just
mind bending. Yeah, and so hopefully it's going to explore
three of the four main moons we're gonna talk about today,
the icy moons, the icy Galilean moons of Jupiter, and
it's launching in two right, Yeah, I believe that's the
current plan and NASA is currently putting together the Europa
Multiple flat by mission for the same time period. Alright,

(11:12):
So I mentioned earlier thinking about the Jupiter system like
a solar system within a solar system, and if you
do that, of course you've got lots of bodies out there.
We mentioned the sixty seven known satellites of Jupiter, things
that are orbiting, but a lot of them are very small.
If we do think about Jupiter like a solar system,
it has four main planets, that's right. They stand out

(11:34):
in the most due to the just their sheer size.
And these are Calisto, Ganymede, Europa, and Io. So you
can think of them as it's four scoops on a
on a Jovian ice cream cone, and you get the
following flavors of scoops. You'll get salty craters, magnets, ice,

(11:55):
and of course lava lava. That's a good flavor. Now, Robert,
did you know that you semed to be you're a
fan of ice cream metaphors? I did. I use them
when thinking about planets. I use them when thinking about
the brain. Though, Is this a good way of explaining
things to children? Did they just really grasp onto ice
cream metaphors? You know? I don't know. I guess it's
a good way to explain it to the child within. Um, yeah,

(12:18):
I mean maybe it comes back to sort of like
a Sesame Street mentality, Like I grew up watching these
visual representations, and it seems like it seems like there
were more than one Sesame Street skit that had ice
cream in them, So maybe that that ended up sticking.
I guess that doesn't make sense. But it is interesting
to think about the flavors of each of these moons
because they kind of do each have their own flavor,
especially the inner two. I think yes, Yeah, each one

(12:41):
is is its own weird world, with its own properties,
its own unique landscape, and that's why we wanted to
take our listeners on a journey through each one. Now,
one thing we should mention about all of these worlds
is kind of different than most of the inner planets,
of the solar system that we think about that have
like a soul, uh you know, a solar rotational day.

(13:02):
Is that all of these moons are tidally locked with Jupiter.
The same side of the moon always faces in towards Jupiter. Yes,
almost like they're completely obedient. They dare not look away
from their their master, right, yeah. Or or it's kind
of like in in Mario, you know, they're afraid to
turn their back on the ghosts because that's when the
ghost comes to get you. So we mentioned that these

(13:23):
are referred to as the Galilean moons, and we should
probably explain first how they were discovered and why they're
called the Galilean moons today. The obvious conclusion you might
reach is that they're named after Galileo. You know, he's
an astronomer, and if you assume to that, you'd be right.
That's where the name comes from. That's right. And I
think most of your probably familiar at least a little

(13:45):
bit with Italian astronomer slash heretic Galileo galile He who
was born in fifteen sixty four died in sixteen forty two,
and he was a true Renaissance man. Uh In the Renaissance.
He was also assistant engineer, a philosopher, mathematician, a true
superstar in the history of science and really in the

(14:05):
history of human civilization in general. It's really, it's really
difficult to overstate the importance the importance of Galileo. Yeah,
I mean, often today scientific struggles against ingrained orthodoxy are
framed in terms of Galileo's struggle against the uh the
scientific and religious orthodoxy of the day, both of which
opposed him. Yeah. Well, tell our listeners a little more

(14:27):
about the controversy surrounding heliocentritism. All right, Yeah, well, so
you'll probably associate Galileo with heliocentrism. The idea that the
planets in the Solar System go around the Sun could
have also in the day, in the at the time,
meant that everything in the universe goes around the Sun.
Of course, now we know that's not correct, but we
were still very much working our way outward and our

(14:48):
understanding of the universe. But it was certainly onto something
in the idea that the Earth goes around the Sun
and not the other way around the Earth end all
the other bodies in the Solar System, and so Galileo
did not come up with the idea of heliocentrism. He
didn't invent this. This was a Copernican idea. It was
already in circulation, and Galileo was one of the Copernican
astronomers of the seventeenth century. However, a version of the

(15:12):
geocentric Aristotelian Ptolemaic model was what was dominant in the day,
was what most people believed. And in this model, the
Earth is It's not just that the Sun goes around
the Earth and the Moon goes around the Earth and
all that. It's that the Earth is literally the center
of motion in the universe. So by by a principle

(15:34):
that centers on the Earth, the whole universe just goes
all goes around us. So we're what everything else is
focused on. And the role of Galileo's discovery is that
in observing the sphere of Jupiter's gravitational influence, Galileo provided
new evidence against that type of geocentrism that dominated in
his day. Uh And one one piece of evidence became

(15:57):
apparent in January six when Galileo made his first round
of observations through a telescope looking at Jupiter. So Galileo
also like not inventing heliocentrism, did not invent the telescope,
but what he did do was improved it. He made
a series of improvements to a design of the telescope
that allowed him to resolve farther objects than ever before.

(16:20):
And by the time Galileo got the magnification power of
his telescope cranked up to twenty times, he aimed at
the planet Jupiter and he saw something really weird. As
we mentioned earlier, you can see Jupiter with the naked eye, right, yes, yeah,
and so ancient astronomers had been seeing Jupiter for a
long time. They're already aware of its existence. But what

(16:40):
Galileo saw when he focused on Jupiter was interesting. He
saw stars. He saw three stars lined up right next
to Jupiter, almost as if strung along a spear extending
out through Jupiter's equator. So Galileo made a note of this,
and he decided to check back on it later. Now,

(17:02):
if those had been stars that were just in the background,
you know, if they just happened to line up with
Jupiter from the star field beyond, the next time you
looked at Jupiter, they shouldn't be there, right, because Jupiter
should have moved on relative to the background starfield. Right,
they shouldn't be following the planet because they would be
distant optics based on the planet exactly. But instead the

(17:22):
stars followed Jupiter. Where Jupiter went, the spear of stars followed,
and they changed their positions relative to Jupiter. And so
after some observation, Scalio realized that there are actually four
stars on this spear, not just three. And the conclusion
he realized was that these weren't stars. The star spear

(17:44):
was not a star spear, it was a moon spear.
These are moons that are orbiting Jupiter the same way
Earth's moon orbits the Earth. And so, okay, well, so
Jupiter has moons. What does that mean for the cosmological
debate of the day. Well, if there are moons orbiting Jupiter,
it disproves the Aristotelian principle that Earth is the universal

(18:06):
hub of motion of planetary bodies. Those moons don't orbit
the Earth, they orbit something else. And so this gives
you a kind of general principle of things orbiting things
rather than everything orbiting Earth. And it's clear that there's
more than one center of motion possible. There at least
two that now that we know of Jupiter and Earth,

(18:27):
and if there are two, you can assume they're probably
more than two. And this eventually led to the type
of thinking that showed us what was really out there
in terms of heliocentrism in the way gravity works. Now,
I should also add that the discovery of Jupiter's moons
wasn't unique to Galileo, and he wasn't even necessarily the
only or first person to have discovered them. I found
accounts that at least one other guy, a German astronomer

(18:50):
named Simon Marius, discovered them independently at around the same time.
And it's also been suggested that an ancient Chinese astronomer
named gone Day might have discovered one of the moons
of Jupiter in the fourth century b C. When he
said that he saw around Jupiter a small red star. Now, technically,
under the right circumstances, the moons of Jupiter should be

(19:13):
visible to the naked eye from Earth, and the only
thing that really prevents it is that Jupiter is too bright.
You look up at Jupiter and it's it's so bright
that it drowns out other tiny points of light that
are close to it. So you can't usually see them,
but if Jupiter weren't there, you should be able to
see these objects. Oh but you know what, I think
that sound means that we're coming up on Jupiter's first

(19:35):
gull and moon spiraling in from the outside, and that's
going to be the moon Callisto. Yes, and I think
this is this is a pretty good pit stop to consider.
So Callisto is about the size of the planet Mercury.
It's the third largest moon in the entire Solar System,
and it's the outermost of the four Galilean moons as

(19:56):
we've discussed. Uh, and it orbits beyond jupiter main radiation belts.
So Jupiter is highly radioactive, it's putting out a lot
of scary stuff, but Callisto is far enough away that
it's relatively safe. That's right. Yeah, we're we're outside of
that that that deathly the death z. Yeah. It's also

(20:18):
the most heavily cratered object in the Solar System, so
that's interesting. Yeah, this is this is really fascinating. So
as we as we as we we get closer and closer,
as we're able to observe the surface of Callisto, and
maybe I mean hopefully even get out even land our
vessel and find a semi permanent home on this, uh,

(20:38):
this this strange moon. You would find that that the surface.
To to walk the surface of Callisto would be to
walk a dead landscape of craters and occasional small icy peaks.
And this surface, this landscape has not changed in four
billion years. Yeah, that's one of the things that we
often associate having heavy cratering with, right, like more cratering

(21:01):
you see the older the surfaces, because what does cratering mean.
It's been like that a long time without any kind
of repaving, that's right. This was the last time Callisto
suffered any extensive resurfacing was four billion years ago. And
there are no plate tectonics, there are no volcanoes, a
no active geology to alter the landscape. So it seems

(21:24):
like a kind of quiet, serene dead Yeah. I mean,
it's like a dinosaur world. Right. It's like the moon
itself is only four point five billion years old, and
again it hasn't changed in four billion um. It's also
the darkest of the four moons that we're discussing here,
in the least dents. So Callisto's composition is about half
water ice and half rocky material. And the mean surface

(21:48):
temperature of Callisto is negative two and eighteen point forty
seven degrees fahrenheit, and the thin atmosphere consists of mostly
carbon dioxide. Okay, so it may be very quiet and
serene on this, on this seemingly dead rock. But should
we take away from that that Callisto is definitely not
a place to look for signs of life. Well, I

(22:09):
think we've both watched enough science fiction to know that
that world that you land on it seems dead is
never It's not always really that dead. I have a
sidetrack to take here. Do you notice how in science fiction,
whenever you land on a planet that does turn out
to have hostile aliens on it, you never land where
the aliens are doing something right. Then you always land

(22:32):
in somewhere where there's no sign of them, and it's
only after exploring for a while that you run into them. Yeah,
it would be it would be interesting to have that
story where the ship touches down and all the hideous
night creatures are already out, you know, viciously killing the
eight creatures that lived there during the day. I like
how the the viciously killing motion you made was like

(22:53):
lopping with shears. Yeah, like I'm thinking like two big
old picture arms that are just for stabbing apes. Um,
so we're not thinking about big pincher arms on Callisto.
But there might be something to look for here, right,
that's right. Surprisingly for a world that we've described in
these terms, you know, it's just being this dead crater landscape.

(23:13):
There is some talk of life on or more specifically
within Callisto, specifically the possibility of an electric, salty subsurface ocean.
So you're probably wondering, well, where do we Where did
we dream up this idea? How do you say? Who
says yeah, because you could say you couldn't you say
that about any world like oh, well maybe there's an
ocean beneath mercury. Now, so there's life on the moon.

(23:36):
Come on, it's so spiders from that what's that horrible movie?
Horrible movie with spiders? Pick one. It's a rich, rich tapestry. Okay, sorry,
who said this about Callisto? Well this comes from a
doctor Krishn K. Corona of U c l A and
his colleagues who examined Galileo's measurements. Not not Galileo, the
scientistic Galileo, the spacecraft that we mentioned earlier. Uh, the

(24:00):
they examined galleos measurements of Callisto's magnetic field, and they
noticed that the magnetic field fluctuated in time with Jupiter's rotation. Okay,
so what does that mean. It means that Jupiter's powerful
magnetic field was creating electrical currents inside of Callisto, and
those currents in turn created a fluctuating magnetic field around Callisto.

(24:24):
Now for that to happen, you need a conductor, and
that thin uh atmosphere crater scape that we've touched on earlier,
that's just not gonna cut it. What would work, however,
is a salty layer of melted ice down there, a
subsurface ocean electrolytes. Yeah, it's what alien life. Yeah, a
sub world gatorade ocean, if you will, so cautiously, very cautiously,

(24:49):
there is the potential for extreme of file life within
this theorized subsurface ocean. There's liquid water, perhaps salty, there's energy.
So we'd be talking micro if we were to, you know,
consider life using our only model of it, which is
Earth life, we'd be talking micro organisms like our keya bacteria,

(25:10):
salt loving bacteria. There wouldn't be any gigantic electronic moon whales.
There wouldn't be any uh, there's certainly no mandible eight
stabbing creatures. But and of course it would also be
very cold, and the ocean would only be heated by
radioactive elements. So it's a very very very very hostile
environment that we're picturing here. But based on our understanding

(25:33):
of life on Earth, it would not be impossible for
something to have evolved and and even thrive there still. Yeah,
and though we do want to point out that when
we think about what hostile to life is, we're thinking
about hostile to Earth life, right, And of course the
Earth environment might be incredibly hostile to organisms adapted to
some other kind of world. So, like you know, on Earth,

(25:56):
on Earth we have oxygen and oxygen app sphere. Oxygen
is nice to us because we're adapted to it, but
it could be highly corrosive to some other type of organism. Yeah, indeed,
So you know, with all this, it's it's relative based
on our human perspective and our our preference for all
things that support human life. Now, as far as the

(26:17):
exploration goes, we've we've had nothing Callisto specific in the past,
but most missions to or by Jupiter involve some level
of Callisto study. I mean, you're you're, you're swinging by.
It's in the neighborhood, it's one of the four largest moons.
You're you're gonna get some data off of it. Now,
I know we mentioned earlier the juice, the juice is

(26:38):
thinking about studying icy moons of Jupiter, and that would
include Callisto right indeed. And then as far as considering
any kind of far future visitation of specific study there,
NASA's two thousand three Human Outer Space Exploration or HOPE
project suggested that in a hypothetical five Jovi mission UH,

(27:01):
Callisto could serve as a base of operations UH for
study of Jupiter UH as well as other Outer Solar
System concerns thanks to its stable geology and low radiation.
So again, nothing's changing their no earthquakes, there, no volcanoes,
and you're outside of that death zone for the most part.
So it would be a great place to U to

(27:22):
UH to tell operate say a Europa submarine, we'll get
into Europe in a little bit, a little bit or
or other. Galilee and Moon explorations. It could also serve
as a way station for outward bound vessels. I think
that teleoperation idea is very interesting in the future of
space exploration because one of the things you often run
into and space exploration is, well, Okay, when you've got

(27:43):
a job that's very dangerous and and requires an extremely
hardy explorer, you think, okay, we need a robot, right.
But then when you've got a job that requires quick
thinking and adaptability, you think you need a human explorer because,
I mean, a robot is not going to be able
to figure out how to get around a problem very
easily if you didn't anticipate it in advance. And a

(28:04):
good way I've heard of of bridging this gap is
having teleoperated robots. So instead of putting a human on
the surface of Europa, you have a human in some
nearby vessel, in a you know, spacecraft orbiting Europa or
some or nearby on callisto maybe, and they are essentially
by by avatar type of control, making a robot do

(28:27):
what it needs to do, but also being able to
adapt to unexpected conditions and problems. So you send a
robot to Europa, and you send maybe like a human
brain and a scream canister to Callisto to remote control
the robot in Europe. I feel like, after reading about Callisto, though,
I kind of felt bad for Callisto reading this proposal,

(28:47):
because I'm like, you landed on Callisto. Callisto's cool, Callisto's fascinating.
Don't get to Callisto and then dream of Europa. That's
kind of inconsiderate. That's like, you're you're hanging out with
this friend, don't text that one the other one during
the hang But I mean, what if this other friend
you're texting is just way more likely to have life
on them. It's true, it's true. Okay, I think we're

(29:07):
gonna take a break, but when we come back, we're
going to get into the three inner Galilean moons where
things really start to get interesting. Alright, we're back. We've
left Callisto. We've left that dead, cratered world and it's

(29:28):
uh potential salt ocean hidden beneath its surface. What is
our next destination in our journey? Well, our next destination
isn't going to be all that different from Callisto in
many respects. So we left one cold, icy, rocky world.
And we're headed to another cold, icy, rocky world, but
this one is Ganymede. Now what the basic stats on

(29:50):
Gannam Ganymede is about in diameter about three thousand, two
hundred and seventy three miles across or five thousand, two
hundred sixty eight kilometers. This makes it the large just
moon in orbit around Jupiter, and not just there. In fact,
it's the largest moon in the entire Solar System. It's
bigger than Pluto, bigger than the planet Mercury, but not
nearly as massive due to low density composition. So you

(30:16):
take an interior cross section of this planet, imagine you
could shear away half of it and look at an
interior profile. You've got an iron core kind of like
Earth has, but it's also possibly partially molten iron, and
that's important for something I'm gonna get to in a second.
Then around that iron core you've got a layer of

(30:36):
rocky inner mantel that's so like silicate rock standard rock.
And then around that is a layer of water ice
probably also some salty liquid water. And then finally on
top you've got an ice crust that shows signs of age,
craters and scarring. So the molten metal in the iron

(30:57):
core is probably why Ganymede has its own magnetosphere like Earth,
and and the fact that it has its own magnetosphere
is interesting. A lot of objects in the Solar System don't,
but don't have a magnetic shield that extends outward from
the planet, which makes possible visitation to those worlds all
the more problematic. So I'm thinking this, I mean, we

(31:18):
missed Coldisto. This one sounds like a good place to
touch down. What's it like on the surface. Okay, well,
let's take a little tour of the surface of Ganymede.
First of all, you're gonna notice as a thin oxygen atmosphere,
but the emphasis is on thin. It's not thick enough
that you could breathe it, but there is gonna be
a little bit of gas around there. And imagine you
step out of the spacecraft. Say, okay, anamie, So you're

(31:39):
walking on ice. The crust of the planet is ice.
It's this dark, endless plane of ice, possibly with some
rocky elements here and there, but mostly it's going to
be ice. It's like a frozen pond extending over the
whole planet. So bring ice skates. Maybe actually I wonder,
you know, if so ice is slippery here on Earth,

(32:01):
is ice slippery on Ganymede. I have no idea why
I would even wonder that. I would have to assume
the physics are somewhat similar, but maybe not. I mean
it depends. Yeah, there's it's easy to take for granted
something like ice skating, but ice skating it it's going
to depend on I don't know what the gravity is
like on the world, right, Yeah, yeah, gravity and the
surface conditions. Now, one thing actually I think is that

(32:23):
ice is less slippery the colder it gets outside, right,
like an extremely cold conditions, you're less likely to slip
on the ice. I feel like the novel that Forever
War went into this a little bit. I believe like
there's a section where he was getting into like the
physics of being a visitor to an icy world and
how slippery would be. But it's a long time since
they've read that. Left up here from listeners. Yeah, I

(32:44):
would like to hear if you have ideas about that.
But anyway, you're out on this ice crust, and one
thing you can notice is that you can, as you
travel the surface of Ganymede, move from different kinds of
landscapes into one another. So Ganymede has interlocking sections of
an old face and a young face. Both are made

(33:04):
of ice, but the old face is dark, covered in
ancient craters from impacts over billions of years. That's what
we talked about earlier. You know, the more craters you
see on the surface, typically the older it is because
it's been there to absorb blows from the shooting gallery
of the Solar system for a longer period of time. Yeah,
be aware of those plants where you don't see craters

(33:25):
everywhere because something's happening there. Yeah. The craters on Ganymede
i've read, are actually relatively smooth and gentle, and this
possibly might be from millions of years of ice settling.
So unlike rock, where there's a crater, it's a brittle
crater with edges, and it remains that way for a
long time. With ice over a long period of time,

(33:46):
even though it's very cold, there is some kind of
almost kind of gelatinous quality to the ice over long
enough time scales, so it'd be kind of like kind
of ice jelly. It's kind of like the way glaciers
can deform for a long period of touch um. But
then there's also a younger ice plane on the surface
of Ganymede, So you can move from one dark, scarred

(34:09):
plane to another one. And these these younger ice planes
are brighter in color, with fewer craters, and instead of craters,
you'd walk through these deep grooves known as sulki. Each
each of these it's a sulcus, is this groove running
along the surface of the planet. It's like a wrinkle
in the face of Ganymine, the sulki of Ganymede. I

(34:31):
like it. Yeah, it's beautiful. And what are those caused by? Well,
it's not exactly known, but I think the main idea
I've read is that it's caused by internal stresses, entitled
forces acting upon the planet, kind of causing wrinkles and
perturbations in the crust. Okay, well, what are the natives
like here? Well, if there are any, and there actually

(34:52):
is a possibility, it's going to be kind of like
what we talked about with calisso a similar kind of situations.
Because findings announced by NASA in from the Hubble Space
telescope showed that Ganymede probably has liquid underground oceans. Sandwich
between I see layers. And they figured this out by
looking at at the aurora around Ganymede and figured out

(35:13):
that you know, to see the to see the charged
particle displays that we see around the outside of Ganymede,
we would probably be expected that we would probably expect
that to be caused by liquid oceans under the surface.
Uh and anywhere of course that there's liquid water, we
kind of have to wonder is there a possibility, And
so that's the idea, and it's another case of subsurface

(35:35):
liquid water that may indeed harbor microbial life. Now, past
observations of Ganymede have been done by the some of
the same missions we've talked about in the past, the
usual suspects here, and of course Ganymede is one of
the potential targets of juice that the juice it's so
it's we mentioned earlier, but it's part of the Essays
Cosmic Vision program. And the idea is that the probe

(35:58):
would launch in putting it on course to arrive in
the Jupiter System around twenty and it would make observations
of Jupiter itself, but also Europa, Ganymede and Callisto and
the main focus on Ganymede would be to learn more
about its underground oceans and whether they have the potential
to sustain life. But in addition to that, there are
some Russian scientists who want to put a lander on Ganymede. Again,

(36:23):
this would be to study potential habitable habitability. But this
wouldn't just be a fly by. This would be a
probe settling down on the surface and uh and using
various tools to figure out what's going on on the
surface of Ganymede and and what might be going on
under the surface. Indeed, as a tantalizing part right to
to not only arrive there, but to but but to

(36:43):
but to actually dig down into the surface and see
if these oceans are really there and then what it
consists up. Yeah, and of course Ganymede is not the
only place where scientists want to drill under some ice
and look at habitability concerns. In fact, there's an even
better spot to study that, and it's the one that's
coming up next on our death spiral into Jupiter. That's right, Europa,

(37:08):
and Europa is quite a big one in our in
our consideration of Jovian moons. Yeah, if you read science fiction.
I bet this is the most likely one you've read
a story about, and it's often I would say, would
you agree that of all the places in the Solar System,
it's the one where astrobiologists most often talk about the
possibility of finding life. Yes, this is definitely the one

(37:31):
where where that has the most excitement around it. Yeah.
So Robert introduced us to this moon we're coming up
on now, right. So one of the surface of Europa
appears to be a solid sheet of ice. Scientists believe
this outer shell hides a deep liquid ocean or an
ocean of of ice slush underneath, the heated by tidal
friction and thermal vents sixty two miles beneath Europa's ice caps.

(37:57):
So Europa boasts a layered structure like Earth that consists
of an iron core, a rock mantle around that core,
a thick soft ice layer, and a thin crust of
impure water ice over again what is probably a global
subsurface water layer. Yeah. And so though Europa is a
little bit smaller than Earth's moon, based on the Galileo data,

(38:18):
you know, the data from the galileto trobe again not
from Galileo, galile a uh, scientists think that Europa actually
has more water on it than Earth does, which is
pretty incredible because Earth is often known as the water planet.
So if you you are the aliens from signs, it
is even worse to try colonizing Europa than Earth. Now
that ocean finding, as with Callisto's suspected subwa subsurface waters,

(38:43):
come down to the Galileo spacecraft's measurements, specifically the manner
in which Jupiter's magnetic field was disrupted in space around Europa,
and the theory is that the field is induced by
a large body of electrocly conductive salty fluid beneath the surface. Now,
if we're to actually move in a little closer, if

(39:04):
we were to touch down on Europa, what would we find. Well,
the surface is apparently a vast landscape of frozen ice,
and it's crisscrossed by long linear fractures, and these are
caused by tidal flexing, the tidal force caused by Jupiter's gravity.
There are a very few craters to be seen blemishing
this landscape, as the surface is actually quite young, only

(39:26):
forty nine million years old, which is kind of creepy
when you think about it. Yeah, this this ancient planet.
We've never been there and it's got a young surface. Yeah,
that's that's the first red red flag for any sci
fi visitors. Right now, you'll also spot reddish brown materials
and some of the fractures and splotchy deposits. So we're

(39:47):
not yet sure what those are exactly. It might be
magnesium sulfate, maybe sulfuric acid hydrate. You know, I think
I've read that recent research suggested that the dark discolorations
on Europa's ice crust could be caused by sea salt
supposed to radiation. Yet another piece of evidence that the
water below the ice crust might be salty. Well, there

(40:08):
you go. Now you'll also come across pits and domes
in the ice that suggests that it could be slowly
turning over or convicting due to heat from the possible
oceans below. Or maybe they're just the dome cathedrals and
fighting pit of some weird off world elder species. Right now, now, wait,

(40:28):
a second heat coming from the oceans below. Now that's interesting. Yeah, yeah,
that's because if there's heat, that's one more possibly not
only do we have a salty ocean, but there's there's heat.
There's energy there, energy rich, yeah, energy rich, more potential
for life. Now there's also the chaos terrain. This is
one of my favorite terms in astronomy, or is it astronomy,

(40:48):
I don't know, astrogeology, planetology, Yeah, I guess so. Yeah,
the chaos terrain. This is a broken, blocky landscape covered
in the mysterious reddish material that we mentioned earlier. So
it might be spots of geo geologic activity. It might
be places where the ice is collapsed into lakes in
the ice. And it's also possible that we're just merely

(41:10):
over interpreting h imperfections in the Galileo spacecraft imagery. Oh yes,
and as revealed in the in two thousand thirteen Hubble
telescope data, Europa is actively venting plumes of water into space.
So this means that it's definitely geologically active. So it's
like geyser is shooting off of the Yeah. Yeah, So

(41:33):
so we've got that to think of two, like space
geysers shooting water into space. So does it have an
atmosphere at all? It does. It has a molecular oxygen
an O two atmosphere. Hydrogen floats away from the planet
because it's too light and collects in a gas torus
around the planet. Less impressive than than the one on

(41:54):
Io that will discuss, but still pretty pretty interesting. Nonetheless,
And it's our size goes for your Europa. It's slightly
smaller than Earth's moons. So Europa is the smallest of
the four Gallean moons. Yes, but size doesn't necessarily matter
when it comes to subsurface life, that's right. So if
Europa's oceans do exist, and we're pretty sure they do, Yeah,

(42:17):
it's I think most scientists agree that that's what's what's
going on under there. Then the tides might also create
volcanic or hydrothermal activity on the seafloor, supplying nutrients that
could make the ocean sustainable for living things. Yeah. So
often when you want to imagine what kind of alien
life could exist on plate in places other than Earth,

(42:38):
it's a good idea to look at extrem a files
on Earth, what exists in some of the most difficult
conditions on Earth. And one of the things to look
out on Earth might be the life that is sustained
by hydrothermal vents on the ocean's floor. Yes, we're talking
about deep, dark places where really the only font of
energy is is the the the hydrothermal vent. But that is,

(42:59):
you know, pumping out some very high temperatures in an
otherwise cold and lightless environment. And uh and there are
there are organisms that have evolved to thrive in that environment.
But again it's to go back to what you said earlier,
we call them extreme of files. But of course if
that were the only place life could exist on a world,
would they really be extreme of files? It kind of

(43:20):
depends on how you know, where you're approaching it from. Yeah,
that's what they're adapted to. Yeah, I mean try to
put them in a in a lush farm land on
Earth and then die out, that would be their extreme environment. Yeah.
So there's a lot of a lot of hope, a
lot of excitement, uh, specifically for Europa because a number
of the factors uh in the or in the emergence

(43:41):
of life seemed to exist there. Yeah, and because of that,
Europa is a prime target for future exploration and research.
So if we mentioned juice, Juice wants to go to
Europa of course, but what else is going to Europa? Well,
NASA is currently putting together the Europa multiple fly by
mission for the same time period that mission is scheduled

(44:02):
launch in arriving at the Jovian System in two seems
to be a big year in general. According to a
BBC report from actually earlier this month, NASA is eyeing
that year as a potential launch date for a soft
landing mission to Europa. Also e s A. Scientists are
currently considering these five different concepts um for their own explorations.

(44:26):
So one is a remote sensing instrument that would go
aboard the that American two probe. Another is a small
free flying satellite that would detach from this probe. Another
is a small satellite that would detach from the lander's
mother ship. Another is one or two instrumented projectiles that
would drop from the mother ship. Projectiles. Yeah, and we'll

(44:49):
we'll get to to the projectile aspect here in a second.
Also an instrument to ride on the soft lander and
uh quote quote do science at the surface. Um U.
I love it when landers do science. Yeah, I mean,
it's one of those things where it's you know that
when in the early enough stages for figuring out exactly
what it would do, but then we also know a
number of the science that it would do. But then

(45:13):
the one that really is fascinating is the idea of
a penetrat or hard lander. So this would be a
steel missile loaded with sensors that strikes at three hundred
miles per second and collect data on the interior. So
we're talking some very rugged instruments. They've apparently tested this
out a little bit on Earth, uh and found that, yes,

(45:34):
that the instruments do survive such an impact. Well, that's
one of the interesting questions is what we would do
to get to that subsurface ocean, because so you'd have
to if you land on the surface of Europa, if
you imagine it has an extremely thick ice crust and
the subsurface ocean is underneath that, you'd have to drill
down or melt down to get to it. And then

(45:55):
once you're down there, how do you get the data
back up to the surface. Right, And and we don't
want to discount just the journey to any of these
moons in general, because this is not like the friendliest
neighborhood to enter into. Your kind of entering. As we mentioned,
you're kind of going into a sub solar system with
plenty of objects singing around with rings, etcetera. So it's uh,

(46:17):
there are a number of factors that there are a
number of hurdles to even getting to your destination. Now, Robert,
have you seen the science fiction movie Europa Report. I
have not. I really liked Europa Report. I I would
be interested in hearing what you guys out there think,
our listeners. Have you seen this movie? I thought it
was cool and that it was a modest science fiction

(46:39):
movie that did it did a lot with a little
and one thing I really liked about it is that
it was truly a science fiction movie about the exploration
of Europa and science fiction, I mean, um, a lot
of movies that are called science fiction are really just
sort of action fantasy where the instead of having magical weapons,

(46:59):
you have technolog logical weapons, but they're still basically the same.
The viewer that has no idea what it's just. Instead
of to be having a religious or supernatural explanation for
the magic, it is a vaguely science explanation for the magic. Yeah, exactly.
And this movie was not like that. I mean that
it was a science fiction movie in that the plot
was inherently about science. It had a it has scientific

(47:22):
plot and a scientific thrust, and the characters had a
scientific mission that was actually grounded in real things we'd
want to learn in the real ways we'd go about
trying to learn them. Uh, And so I won't I
will try not spoil anything about the movie. But they
it's a movie about a manned mission, or I should say,
a crude mission, a mission with a crew going to

(47:42):
the surface of Europa and trying to figure out if
there's life in the oceans underneath. And so I give
it a thumbs up. This hilarity against it, No, not
really hilarity, maybe some Without spoiling too much, I will
say that things don't go exactly to plan. If it
wouldn't be much of a moon. Alright, Well, at this point,

(48:04):
let us sadly leave Europa um with its mysteries unsolved,
and continue on to the innermost of the Galilean moons. Yes,
now does time. We're approaching Io. It's spelled two letters io,
and that seems to make sense. But because there's a

(48:25):
kind of grinding simplicity and beauty and weirdness to this planet,
it's it's it's maybe the strangest and most gorgeous of
all of them, and of all of them, it most
wants to kill you. So IOW is Jupiter's innermost Galilean moon.
In terms of diameter, it is slightly, but only slightly

(48:47):
larger than Earth's moon. It's almost comparable in size, and
its orbit keeps it within four hundred and two kilometers
or two hundred and sixty two thousand miles of Jupiter.
That's not not a whole lot farther than the distance
between the Earth and its moon, except think about how
big Jupiter is. Yeah, yeah, so what's yeah, So, what's

(49:12):
it like on the surface of Io. It's freezing hell
and burning hell at the same time, where the ground
that you walk on churns up and down like a
tsunami as the tides go in and out. On the
solid world, Io is a world of extremes. It's uh.
It's the most geologically active object in the Solar System,

(49:34):
the whole Solar System, including Earth, with more than four
hundred active volcanoes that we know about. Some eruptions of
these volcanoes shoot ejecta plumes of three hundred kilometers or
a hundred and eighty six miles out into space above
the surface. If you see some images of these, it's incredible.
It looks like it looks like there's something else going

(49:55):
on behind Io that's being obscured by the planet. But no,
you that's not what it as. You're just seeing in
profile plumes of planet sized proportions exploding off of the surface.
And uh. And so the average temperature on the surface
is negative two hundred and two degrees fahrenheit or negative
a hundred and thirty degrees celsius, which is far colder

(50:18):
than the coldest natural temperature ever recorded on Earth. That is,
unless you're standing near one of Io's hundreds of volcanoes
while it's erupting, and here the temperatures are more like
three thousand degrees fahrenheit or one thousand sixty nine degrees celsius.
There is an atmosphere, but it's thin and mostly made

(50:39):
of the toxic gas sulfur dioxide, which is often associated
with volcanic activity even on Earth. So if you know,
you get killed by toxic fumes near a volcano or
something like that, you may be breathing sulfur dioxide. And
speaking of sulfur compounds, the planet is also going to
be covered, probably in fields of yellow snow. You don't

(51:02):
eat the yellow snow in this case, and it's because
it's sulfur dioxide snow. So the planet it has these
eruptions where these particles of sulfur dioxide gas come out
and go all around the planet. But then because it's
so cold, they tend to crystallize and fall down as
the sulfur dioxide yellow snow. Uh. So it's just covered

(51:23):
in these poisonous golden snow fields. But other than that,
it's a good place to visit. No. No, it's also
a blasted heath of radiation. So uh, it's the closest
to Jupiter and the most exposed to Jupiter's radiation. And
then there's also because Io is connected to Jupiter through

(51:44):
a sort of magnetic ring that comes out of Jupiter's magnetosphere,
it also creates what's called a plasma torus, which is
just this ring of killer charged particles flowing off of
Io and into Jupiter. Er uh. And it's it's kind
of unbelievable. You wouldn't want to get near it, you

(52:04):
wouldn't want to stand in it. You really don't even
want to fly a probe through it. And I mentioned
earlier the tidle heaving on Io. So on Io there
there are tides, but there are no oceans. It doesn't
have water to have tides. It has tides in the
ground itself. Now other planets well too, tides of course,

(52:26):
you know, being influenced by the gravity of surrounding bodies.
There's there's tidal action acting on Io from Jupiter and
from the other moons that are going around Jupiter. But
these incredibly powerful gravitational forces, instead of moving water around
on the surface, end up moving the ground up and
down hundreds of feet. Now, from what I understand, I

(52:47):
think you wouldn't feel this like you know, waves coming
up and down really fast or anything like that. But
it does. This tidle flexing and stretching of the solid
mass of the planet does lead to incredible old friction.
I mean, think what would happen if you were constantly
flexing a rock in and out. We get pretty hot,
and this is what happens to the interior of Io,

(53:09):
leading it to be this burning hellscape within the freezing hellscape.
Another crazy fact about Io Jupiter is going to loom
huge in the sky. The NASA JPL website has a
really interesting app that I recommend you try to use. It.
It's the Solar System Simulator, which lets you simulate looking

(53:30):
at one object in the Solar System from another object
in the Solar System at any given time. Uh. And
I tried this out. I was like, Okay, what does
it look like looking at Jupiter from Io right now?
And from the surface of Io right now? Jupiter currently
takes about it takes up about nineteen point five degrees
in the sky. So you know, imagine the degrees from

(53:52):
horizon to horizon. You've got about a hundred and eighty degrees. Uh,
so this is about twenty degrees. That's like one ninth
of the width of the sky. It's crazy to imagine that.
I mean, it's it's crazy to imagine even course, standing
on the surface of Io and you're I guess God
likes space suit that somehow protects you from all of
these extreme conditions somehow, I think we're not ever going

(54:14):
to be walking on I yeah, I mean you would
have to be dealing with like a what like a
level level one or level two civilization just kardashiv yea
Cardassian level like like some sort of like crazy sci
fi field system like where it wouldn't even be a
physical suit as much as like a crazy energy field

(54:36):
that is somehow protecting you unless you're Sean Connery with
a shotgun. Right. Oh yes, Um, is it too early
to mention Outland? No, it's not so. Before we recorded
the episode, we were talking about how Robert just rediscovered
that the movie Outland, the starring Sean Connery, which is
essentially high Noon in Space. Yeah, it's a space western,
nice and gritty. It's it's it feels like you could

(54:58):
take place in the same universe as Alien. It's, you know,
a lesser film, but it has that kind of grimy
um you know, Workman's vision of life in the solar
opposite of Flash Gordon. But it takes place on Io.
Right again, how realistic is that? Seems not very Yeah,
it's been a while since I've seen it, but I

(55:18):
do not recall the I do not recall any highly
volcanic scenes. I could be wrong on that. I felt
feel like they delivered like a cold or vision of Io. Yeah,
but it's a great film, very violent, a very very
gritty space drugs, space prostitutes, Sean Connery with a shotgun,
Peter Boyle uh and some other actors that would go

(55:40):
on to make a name for themselves and in the
cast as well. Is it kind of like Leviathan in space?
Not really, there's no monster. It's like it's a very
human story. It's it's essentially you know, it's it's a
mining town Western scenario. But on this Jovian, I guess
I was just going with the mining outpost sect to Leviathan.

(56:01):
Do we need to talk about Leviathan on this podcast?
We can carry on. Sorry, I've seen that one more recently. Yeah,
well it does have a great poster, it does. Okay,
So back to Io. Given everything we've said so far,
freezing hell and burning hell, uh, sulfur dioxide, vicious radiation bath,
we shouldn't expect to this place to have any life

(56:24):
at all, right, it seems a ridiculous proposition. Also, no
liquid water on the surface. It sounds like the last place,
no organic molecules ever detected there, I mean, why ferocious radiation?
So we can definitely rule out the possibility, right, Well,
actually not according to everyone. And I wonder if this

(56:45):
is just an expert uh an astrobiologists trying to emphasize
what possibilities are out there, more thought experiment than anything
it could be. But from two thousand ten, I found
an article by Charles Q. Choi that speaks to Dr
Dirk Schultz may Cooch uh an astrobio, an astrobiologist at
Washington State University, and uh. Dr Schultz may Couch said quote,

(57:09):
life on the surface is all but impossible, but if
you go down further into the rocks, it could be intriguing.
We shouldn't categorize it as dead right away just because
it's so extreme. So based on this guy's comments, this
astrobiologist comments, the article went on to sort of explore
what life could be like on Io. You know, if

(57:29):
we if we look at Europa and Ganymede, which have
water ice, we can get a picture closer to what
Io might have looked like billions of years ago, closer
to the time of its formation. Radiation from Jupiter probably
would have ripped away Io's water within about ten million
years or so, but life that evolved on the surface
during that period could possibly have retreated underground, surviving in

(57:52):
subterranean lava tubes, which could contain moisture and protect the
microbial life forms from radiation. That's on io surface. What
what is impossible up above may not be impossible below,
And as we've pointed out before, they're extreme a file
organisms on Earth that can survive and thrive in lava
tubes and even near active geothermal hotspots like Geyser's. So

(58:15):
Shultz make each comments that the ultimate chances of finding
life on Io seem pretty low, but we shouldn't rule
it out. And besides, how amazing would that be to
find life on this sulfurous golden hell. It would really
change your idea of what's possible for self replicating organisms
in the universe. I think, indeed, you know, and it
also makes me want, you know, we've thought we've been

(58:37):
discussing some sci fi a little bit here, but you're
always encountering that idea of of of either a human
or other intelligence civilization seating life in other worlds, and
generally that doesn't take the form of extreme of files.
But but I wonder, like, what could we one day
reach the point where a human or human derived civilization
would reach a world like like Io. Look at it,

(59:02):
determine that there's no even there's no life, even extreme
file life. But then custom makes something to survive, and
it's like it's in its most tolerable um locations. I
don't know, it's fun to think about. Yeah, well there,
I mean, I think you get into, of course, the
ethics questions about seeding life. You know, you'd have to

(59:23):
be sure if that's even possible that there was no
life there now and that life wasn't you know, in
store for it at some point in the future. Um
so who's to say. But then again, I think that's
kind of weird, Like I feel this ethical intuition that
you shouldn't go about, you know, contaminating other worlds with

(59:43):
possible life that could extinguish the life that exists there now.
But then again, I really don't feel bad about using
alcohol to kill bacteria if you're washing your hands before
surgery or something like that. You know, it's I don't know, Well,
you know that the bacteria was never going to make
a dial anyway, so it's fine. I guess. So alien
bacteria just has so many more rights than Earth bacteria. Okay,

(01:00:08):
So future missions to IO one would be the Io
Volcano Observer one proposed future mission at least we don't know,
but uh, the proposed future mission to IO would be
this observer. Primarily the work of the planetary geologist Alfred McEwan,
And this would be a probe that goes into orbit
around Jupiter and observes Io close up over the course

(01:00:28):
of at least nine flybys over two years. And this
would be studying Io's temperature, it's a volcanic activity and
its surface composition. And if the proposed mission is accepted,
it's going to launch by around one So it seems
like in the early twenties there's gonna be a lot
of potential Jupiter missions launching. That has got to be
a I mean, we've already discussed the volcanic eruptions that

(01:00:51):
blast out into into space ye off of Io, so
that would see it would seem like it would be
a difficult orbit to maintain, and maybe that's part of
the gamble, like how well I mean, I guess question
would be exactly how close is it getting to Io
if it's gonna be orbiting Jupiter that I think I
read something like that the closest point it would ever
get to Io would be around two kilometers away, which

(01:01:11):
is I mean, that's pretty close. But the bigger question,
I think, much more than the geologic activity, is just
the radiation. I mean, even even non organic you know,
just our instruments at that point are going to be
subject to extreme radiation, and so it would have to
be a hardy kind of probe to survive. If anything
were to actually land on Io, it would have to

(01:01:33):
be a flying fallout shelter. As we mentioned, the radiations
fierce and it has damaged instruments on probes in the past, right, Yes,
I mean that's how that's how potent the radiation of
Io is. One last thing I wanted to add about
Io coming from the angle of exo theology. Uh, the

(01:01:54):
religion space religion. Oh, this is a this is a
topic I love. Yeah, of course I love it too.
And uh, we should add that we keep using the
Hell analogy for Io just merely for descriptive reasons, to
give you an image to map it onto in your brain.
But there's actually at least one theologian who exists who
believes Hell can be found in the Solar System. Uh.

(01:02:14):
He is a guy named Michael sin teeny, and he's
a reverend who he self published a book that argues
that the Christian Hell is literally to be found on
the planet Venus. And I don't know how many people
he's managed to convince of this. This is obviously not
a standard Christian belief. This is his idea. Um, but

(01:02:37):
I wonder why not Io instead? I know, seems like
an even better candidate. Yeah, I mean you have It's
it flows perfectly with Dante's vision, right, because you have
both the hot region, the hot regions, the cold regions.
It's it's perfect. All you need is a Satan there
to his waist. And yeah, and it matches with our
journey of descent, right. You know, as we've gone closer

(01:02:59):
and closer into the planet, which reminds me now that
we've reached the end of our journey, we're getting very
close to Jupiter itself. Yeah, and our our little terrarium
capsule is withering a little bit, was standing the inner
radiation of the Jovian System. I wonder what's going to
happen as we descend into the gas. I don't know.

(01:03:21):
We're descending into a into a massive gas world of
storms and poison and uh and eventually a rocky core
uh with a pressure and the is just insane. I'm
pretty sure we'll be obliterated before we reach the rocky core. Oh, yes, yes, certainly.
I doubt we'll have to reach the rocky core. But

(01:03:44):
maybe there is no rocky core. Maybe the Rocky Core
is all in your mind. Well, the important thing is
we made it this far. I mean, we were ordered
to jettison the dome a while back. We held on
this long. Everything got to survive there, just a little
bit longer, so we can. We can play one last
game of checkers or cards with the robots and just
go out on a high note. Well. One thing I

(01:04:05):
should have mentioned you as we were going, but I
didn't because I was afraid, was that at each moon
we passed along the way, I jettisoned off a capsule
of Earth life, unethically seating these planets and potentially contaminating
them for all future research. But maybe these little life
forms will take hold. Yeah, well, hey, that's better than nothing, right,
So let's hope something takes route alright. So there you

(01:04:30):
have it, an exploration of the Galilean moons, just the
four greatest of the Jovian moons in general, but each
one a fascinating world. And uh and the cool thing too,
is that even over the course of the next year
or so, we're hopefully going to learn more and more
about these these places. Yeah, so we want to thank

(01:04:51):
you for joining us on our journey through this solar system.
Within a solar system, the the gas Giant and it's
wonderful sphere of in fluence. Indeed, and if you want
to see images of some of these moons as well
as explore some links out to additional data about them,
be sure to check out the landing page for this
episode at stuff to Blow your Mind dot com. That's

(01:05:13):
the mothership. That's where we'll find all the podcast episodes.
You'll find blog posts, you'll find galleries, lists, videos, links
out to our social media accounts such as Facebook and Twitter,
where Blow the Mind on both of those. We also
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And if you want to get in touch with us
with your favorite fact about Jupiter or its moons, or

(01:05:34):
you want to let us know what you think the
most interesting object in the Solar system is, or where
you think we're most likely to find the life outside
of Earth, you can email us at blow the Mind
at how stuff works dot com. For more on this

(01:05:56):
and pathans of other topics is how stuff Works dot com.
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