Chances for alien life on Jupiter's moon?
I don't know if you heard about this: there are actually a lot of places in the Solar
System where we might find life, and among all of them, Europa is maybe one of the most
promising ones.
Europa is one of Jupiter's moons, and it has liquid water oceans hidden under its ice surface.
But be careful!
This surface is not thin as you might think: it is actually really thick, something like
20 km thick!
One of the possible issues with this kind of surface, anyway, is that it might have
not enough oxygen in order to host life.
In fact, usually, oxygen tends to accumulate on the surface and we don't know how it could
reach the ocean underneath the thick layer.
So it could also be that this ocean of liquid water is a potentially habitable ocean, but
with no oxygen reaching, that would basically be a waste of potential.
Of course, some forms of life could exist living without any oxygen, but it is really
unlikely, or better said: the oxygen presence would give us a better chance to find aliens.
So the question is: is there oxygen on Europa?
We still don't know, and we will need more missions to understand it, but recently some
studies suggested that we might have found a reasonable mechanism for the oxygen to reach
the liquid ocean.
Let's see how.
Everything starts on the surface, on what scientists call Chaotic Terrain, and it is
called so because basically....it is a mess.
Europa's bright, icy surface is a landscape unlike anything seen on Earth.
To start with, in an overall sense, it's quite smooth, with few towering mountains or deep
basins.
Myriad ridges and grooves crisscross the surface, breaking up the landscape.
Many of these features coincide with long, curving streaks that are dark and reddish
in color – some stretching across the surface in great arcs over 600 miles (1000 kilometers)
long.
Elsewhere, domes, pits, and chaotic jumbles of icy blocks hint that warm ice may be rising
from deep below.
Hard layers of ice make up the surface of Jupiter's frozen moon Europa.
Glacial cracks and ridges scar its frigid white plains, carving paths across an icy
shell that conceals a deep ocean of liquid water.
Closer inspection of the moon's fractured topography reveals highly disrupted areas,
called chaos terrains, where blocks of ice appear to have broken off, drifted, and refrozen
to the surface.
Searching for an explanation of how these features formed, researchers studying images
of Europa taken by NASA's Galileo spacecraft have come up with an answer.
As plumes of warm ocean water rise to the subsurface, massive lakes develop inside the
moon's crust—some larger than North America's Great Lakes combined.
Over time, the ice directly above these lakes collapses, splintering into floating geometric
fragments that rotate, raft, and resettle into all kinds of chaotic configurations.
If such things happen, involving ice motion from the surface to the interior and back,
some passages for the oxygen could open from time to time, and we could hope for life on
Europa.
Temperatures on Europa are really low, but there are some zones where the salt concentration
is sufficiently high.
Some of this water could go through the ice layers and as it does so, it catches oxygen,
bonding with it, and bringing it with itself through the ice layers.
What physicists did is trying to recreate these conditions, and see, by means of some
accurate scientifical simulations, what is likely to be happening there.
The idea was actually already there for a long time, but scientists never tried to produce
accurate physical explanations before.
So, for the first time, we have what seems to be an accurate model of what is happening
in Europa.
The team was from the University of Texas, and what they found is that the porosity of
the ice changes with the concentration of the water itself, meaning that the saltier
the water, the more porous the ice is, and the more likely the oxygen is to reach the
ocean.
They call it a “porosity wave”, and what really happens is that, at the salty water
passage, some holes are created.
These holes then close once the water has passed: this way the oxygen, trapped in the
salty water, could reach the ocean.
We don't really know if this is what happens for real, but if this is the case, the underneath
ocean could host 86% of the oxygen formed on the surface, and this could lead to an
ocean sufficiently similar to the oceans on Earth.
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How can we understand if all this is correct?
We need to send some missions that give us thermal and maybe chemical maps of the moon's
surface.
One of these is called Europa Clipper.
It will probably leave in 2024 onboard a falcon heavy, and it will pass by Europa a number
of at least 35 times.
It will thus get data and send them back to Earth.
35 flybys are a lot!
The map we will be able to build with such a huge amount of data will be high-resolution
maps.
However, if Europa Clipper leaves in 2024, we can expect it to reach by the end of the
twenties, and so in the thirties, we will have two missions around the iced moon of
Jupiter, because there's also another European mission, called Juice, that is going to study
Ganymede, but first, it will pass by Europa.
So we can expect Juice and Clipper to bring some revolution in the field of the iced moons.
The Europa Clipper mission is equipped with a sophisticated suite of 9 instruments to
study Europa's interior and ocean, geology, chemistry, and habitability.
The electronic components will be protected from the intense radiation by 150-kilogram
titanium and aluminum shield.
The nine science instruments for the orbiter, announced in May 2015, have an estimated total
mass of 82 kg!
The Europa Thermal Emission Imaging System, for example, will provide high spatial resolution
as well as multi-spectral imaging of the surface of Europa in the mid to far-infrared bands
to help detect geologically active sites and areas, such as potential vents erupting plumes
of water into space.
The Europa Imaging System is instead a visible spectrum wide and narrow-angle camera instrument
that will map most of Europa at 50 m resolution and will provide images of selected surface
areas at up to 0.5 m resolution.
Because Europa is bathed in radiation trapped in Jupiter's magnetic field, Europa Clipper's
payload and other electronics will be enclosed in a thick-walled vault.
This strategy of armoring up to go to Jupiter with a radiation vault was developed and successfully
used for the first time by NASA’s Juno spacecraft.
The vault walls – made of titanium and aluminum – will act as a radiation shield against
most of the high-energy atomic particles, dramatically slowing down the degradation
of the spacecraft's electronics.
So, recap!
It will probably take a lot of time for us to understand if there is life on Europa,
but at least if we found oxygen, this would come up being a really huge discovery, because
our chances to find aliens will be finally enhanced.
But what if we find that one of these chaotic regions can bring oxygen to the oceans?
Scientists are really aware of this possibility, so they are already thinking about the next
move: a lander, on Europa.
If we sent a lander to Europa, we could analyze and melt some ice that had been brought up
from the ocean to the surface during one of these chaotic events, and see if we find some
traces of life.
We could also think of landing on Europa, and digging the ice with the help of some
sophisticated instruments, that could open up an underwater way for a small submarine
capable of reaching deeper waters.
These are not impossible things to do, but we will probably not be lucky enough to see
them happening.
It is more likely our kids or our grandkids will experience such accomplishments.
A lander on the surface of Europa will be however a really hard thing to do because
the moon's surface is really different from anything we have seen before.
So even if we had all the money we wanted, we would not know how to land safely on the
surface.
And even if we managed, we have to take into account that Europa is really close to Jupiter,
and it is quite exposed to radiations coming from the magnetic field of the planet.
This will of course challenge our instruments, which could respond differently from what
we are used to.
We would also need batteries since Jupiter is really far away from the Sun, but we wouldn't
know how to recharge them.
Maybe we could use some plutonium sources, but this is all to be seen.
For example, if you want to be an aerospace engineer, you could be having fun getting
closer to these problems that can't wait to be solved.
Before ending this video, we would like to say another spacecraft that already gave us
precious information about Europa was Galileo Orbiter mission.
The Galileo spacecraft and probe arrived in the Jovian system in 1995, completing 34 orbits
of Jupiter and its natural satellites before the mission's end in 2003.
The puzzling, fascinating surface of Jupiter's icy moon Europa looms large in this color
view, which was taken by Galileo.
This is the color view of Europa that shows the largest portion of the moon's surface
at the highest resolution.
To create this version, the images were assembled into a realistic color view of the surface
that approximates how Europa would appear to the human eye.
The scene shows the stunning diversity of Europa's surface geology.
Long, linear cracks and ridges crisscross the surface, interrupted by regions of disrupted
terrain where the surface ice crust has been broken up and re-frozen into new patterns.
Colour variations across the surface are associated with differences in geologic feature type
and location.
For example, areas that appear blue or white contain relatively pure water ice, while reddish
and brownish areas include non-ice components in higher concentrations.
The polar regions, visible at the left and right of this view, are noticeably bluer than
the more equatorial latitudes, which look more white.
This color variation is thought to be due to differences in ice grain size in the two
locations.
Thanks, Galileo!
Thanks for watching everyone!
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Did you know that Europa could host life?
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