You know that SpaceX already very early on
teased the possibility of Starship landing
on one of the icy moons in the outer solar
system.
But is this proposition even realistic?
And why are the icy moons of the outer solar system such an interesting destination in the first place?
Well, I would say, let's find out.
When Elon first announced Starship in September
2016, or the interplanetary transport
system, as it was called back then,
we were presented a lot of info on the
ITS infrastructure, with of course a heavy
focus on mars.
After all, the ultimate mission of the ITS
was to colonize mars.
However, during the same announcement presentation, Elon also showed an interesting picture
of an ITS standing on a distant object in
the solar system.
This was definitely neither mars, nor any
other object in the inner solar system, no
but this had to be either Europa or more likely
Enceladus, from the look of the picture.
Then during the last Starship update presentation
from almost one year ago, Elon showed this
awesome rendering of Starship with the
mighty giant Saturn and its imposing rings
in the background.
But before we analyze how realistic this is,
Why are the icy moons in the outer solar system so fascinating in the first place?
The definition of an icy moon is an outer
solar system moon, whose surface is composed
mostly of ice.
Such an icy moon may harbor an ocean of liquid
water underneath the surface and possibly
a rocky core of silicate or metallic rocks.
The two best examples are Europa, the second
innermost of the four galilean moons of Jupiter,
and Enceladus, the sixth largest moon of Saturn.
Now why are those two moons in particular so interesting?
Well, because there is strong evidence, that
both moons could have an ocean of liquid water
under their crust of solid ice.
A strong indication for that is for example measuring the induced magnetic field of the moon, which
suggests the existence of a subsurface conductive
layer, so a salty liquid water ocean.
Europa has a diameter of 1500 km, and needs 3.55 days for one Jupiter orbit.
The fascinating surface features you see here
are actually thought to be cracks in the ice
which had formed due to mechanical stress
The method by which the water below this 15 to 25 km thick ice crust is being kept in liquid
state, is by tidal heating.
Jupiter's massive gravitational field is kneading
Europa while it circles the planet,
which of course creates friction, which then in turn creates heat.
Now of course a giant subsurface ocean, and
a high probability of hydrothermal activity
due to Jupiter's tidal forces, leads to the
very strong suspicion, that life might actually exist
deep down in these oceans.
Contrary to earth, this ocean is insanely
deep.
It would have an average depth of 100 km.
that's right, 100 km depth of sheer total blackness and darkness, because no light can ever reach
this ocean through the thick crust going deeper and deeper until at
some point, you might reach the hydrothermal vents.
There, life actually might exist around these warm pockets.
But there is a problem with Europa.
Insane radiation.
If you thought that mars or the moon have
high radiation with 260 mSv and 400 mSv of
average annual radiation dosage respectively,
think again.
Because Europa has 5400 mSv.
PER DAY.
That's right, the radiation on the surface
of Europa is almost 5000 times higher than
on the moon, and 7600 times higher than on
mars.
Or 7.9 million times higher than on earth.
Standing on Europa for only 1 day would most likely kill you, and even one hour outside
on the surface of Europa would
be enough to reach your total safety lifetime dosage limit for radiation
Because it is located in Jupiter's massive radiation
belt, it is brutally bombarded by charged
particles all the time
So yeah, this moon, is probably better left
to robotic explorers.
Our robot friends will drill a hole into the
ice and explore the depths of this fascinating moon
In the Jupiter system, Callisto would be a
much better target.
It is suspected to have a subsurface ocean too
and has much lower radition, since it is located
outside Jupiter's radiation belt.
In the Saturn system, Enceladus is besides
Titan the most interesting destination.
Titan deserves an entire separate episode,
as this celestial body is one of the most
fascinating in the solar system.
Enceladus, is basically a smaller version
of Europa, with a lot less radiation though, comparable
to standing on the surface of the moon.
It is only 1/3rd the size of Europa, and is thought to have a liquid water subsurface
ocean actually we have much better evidence of this subsurface ocean on Enceladus, since the Cassini probe
already flew through plumes of water ice,
which are ejected in giant geysirs from this
fascinating moon.
Yes, there are geysirs of water ice being
ejected from cryo volcanoes on Enceladus
Instead of molten rock, these volcanoes eject
molten ice, so water particles, which fall
back as ice particles onto the surface, and
they also contain molecular hydrogen and sodium
chloride crystals and all sorts of salts.
Complex organic compounds as large as 200
atomic mass units were found too
and these are the right chemical compositions
for the existence of life.
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Cassini found that the subsurface ocean of Enceladus is
about 10 km thick at the south pole.
So not as insanely deep as the one of Europa,
and thus also not nearly as intimidating.
Okay on second thought, 10 km of pure darkness under an ice sheet 30 to 40 km thick is still
a bit too intimidating for my taste.
Here too, we have tidal heating which probably
causes hydrothermal vents, and if there is
life, it too would be concentrated around
those vents.
Ok So I wouldn't go down there, but maybe there will be some brave explorers who would do that.
But could they?
Well, as you know Starship is quite large with
an interior volume of 1000 cubic meters.
However, we shouldn't forget that a voyage
to mars takes about 6 months, with some modifications
maybe 3 months if we're lucky.
But a trip to Jupiter would be years.
A trip to saturn?
Even more years.
and Saturn is 7 times further away from the sun
than mars.
The probe Cassini, with a Venus and Earth swing by needed 7 years to reach Saturn.
Thus, a manned trip to the outer solar system,
launched directly from earth: We'd say psychologically
almost impossible with the current day Starship.
in order to fly to saturn first we would need a base on mars.
Then we have to launch the larger Starship 2.0s directly from Mars to the Asteroid belt.
Then we have to build a base and a refueling depot on Ceres.
Only from there we could plan the next missions to
Jupiter.
after that we should build a base and a refueling depot on Callisto.
Callisto would be a perfect spot for a larger
settlement plus a larger refueling depot.
And only after that we could launch, when the
time is right, a mission from Callisto to
the Saturn System.
so we really need many intermediary steps before we can send Starship to Saturn
Except of course we'd have a giant rotating
Starship 3.0 200 meter diameter spinning
wheel for artificial gravity.
Then of course, we could also launch a direct
mission to Saturn from earth, without the
people going insane on these long multi-year
trips, since this ship would offer a vast
interior space and also artificial gravity.
But with current Starship 1.0 and 2.0 designs,
which would just be a larger Starship with
a diameter of 18 meters instead of the current
9 meters, we only see this happening stepwise.
We think that we need to expand stepwise towards the outer solar system.
We suspect such missions with astronauts on
board towards Saturn no sooner than 2050,
since as we said, for that, we'd need refueling
depots on Ceres and Callisto, and bases on
mars.
Better yet, Bases plus refueling depots at
all said locations.
So, without any major breakthrough of propulsion, be it nuclear thermal, ion, vasimr, hall-thrusters,
you name it, these pictures here would require
many bases and many refueling stations along
the way.
And we didn't even mention the zero-g and
radiation problems on these insanely long
trips.
But ok, let's say it is the year 2050 and
we managed to arrive at Enceladus with a Starship
2.0, making many intermediary stops along
the way, and Starship 2.0 being outfitted with
adequate radiation shielding and some form
of centrifugal rotation.
What comes next?
Well, after landing on Enceladus, the astronauts
would surely set up a base-camp, and they
would have hopefully been smart enough to
bring along a submarine to explore the subsurface
ocean.
Such a submarine would melt its way down through
the thick ice crust.
It would employ heat generated through radioactive
decay of nuclear material, placed at the very
front end of the cylindrical submersible.
It would liquefy the ice in front, and push
the water back to its rear, which would then
freeze again, thus at some point the submarine would have melted through the entire
multi kilometer ice crust and then enter the
ocean.
What the submarine would find there, nobody knows.
It could be small micro organisms like bacteria,
but large flora and fauna near the hydrothermal
vents would also be possible.
It will be a fascinating time for astrobiology.
Starship or Starship 2.0 would of course be
ideal for such missions, as bases could be
immediately set up, with researchers permanently
living on Enceladus, who would remotely control
the submersibles to ever increasing depths
and make new amazing discoveries.
And who knows, one day maybe the submarines
would be large enough to dive down with humans
on board.
That would certainly be an insane experience
for anyone brave enough to participate in
such a mission.
Certainly not me.
And don't forget to vote on the topic for our next Friday's video
And if you think icy moons boring I am more interested in Venus
then you can watch this video here
So thanks as always for watching and then I would say on 2 the future!
