Europa, Ganymede, Enceladus.
All moons in our solar system with one thing in common:
They're suspected to contain liquid water
below their icy surfaces.
And even further out,
we have some tantalizing evidence that maybe worlds around
Neptune and potentially even Uranus as well
could host liquid water.
Even Pluto might have a layer of liquid water
hiding somewhere underneath that icy crust.
Experts think that
if there is life beyond Earth,
these massive oceans are the place we're most likely
to find it in our solar system.
NASA scientists and oceanographers
are working towards missions that hopefully
will end up looking for and hopefully finding
some forms of life,
which may be very different from ours
on those other planetary bodies.
There's an increasing number of missions
and proposals to explore these untapped water bodies,
starting with an expedition to one of Jupiter's moons.
It's called the Europa Clipper Mission.
Europa Clipper Mission is NASA's next foray
into the Jupiter system,
and we're going to search for all of these amazing
indicators of habitability and potentially life at Europa.
Exploring our solar system's
subsurface water oceans
is one of the next big steps in space exploration.
In 1977, during a mission
to photograph the barren, volcanic floor
along the mid-ocean ridge,
scientists found something that totally changed
our understanding of where life can exist.
They collected 3,000 photos of the sea floor,
developed the film onboard the ship.
And as they were going through the footage,
which was very boring
because it was just barren volcanic rock,
they came across 13 photos
that had pictures of large clams in them.
Shortly after that,
the deep submersible Alvin that takes people
to the bottom of the ocean
arrived on the scene and dived on those sites
and found the oases of life,
amidst all sorts of shimmering water
that was clearly emanating out of the sea floor.
The seawater percolating into the seafloor
was being heated by magma
and then rising to discharge as hydrothermal vents,
and those vents were supporting
a previously unknown ecosystem.
Before then, it was thought that
most animal life depended on energy from the sun.
If you move more than about 50 to 100 meters
away from a vent, the seafloor is barren.
And the question is
how do these vents support the life?
Well, clearly photosynthesis,
on which most of our life relies on our planet,
won't work at the bottom of the ocean because it's dark,
and so there's no sunlight,
so that photosynthesis will not be operative.
However, we do have these gases
that contain a lot of energy.
And because of that, there are bacteria
living around these areas and other microorganisms
that are able to extract energy
from those gases
and use it to produce organic matter.
And that matter feeds an array
of exotic animals.
When I first saw them,
my mind was blown
at several things.
One how beautiful they are,
but also how big some of the animals are.
Some of the creatures that you see down there
are tube worms that can grow 6 to 10 feet long,
foot-long clams, big mussels.
And in fact, the diversity around these vents
has been likened to that of the diversity
of a tropical rainforest.
This discovery has big implications
for planetary bodies in the universe with water,
regardless of whether or not they're close enough
to harness the energy of their host star.
It suggests that there's a possibility that
there might be life on other planetary bodies
that have water.
And so in some ways,
this discovery is helping change our ideas about
the potential for life on other planets.
In the decades
since the hydrothermal vent discovery,
evidence has piled up for oceans in the outer solar system.
Both the Galileo probe that visited Jupiter
and the Cassini probe that visited Saturn
were equipped with an onboard device called a magnetometer,
which was able to give substantial
evidence for liquid oceans.
Think of it as like a fancy compass.
Basically any liquid water ocean,
if it has salts in it, it can conduct electricity.
And that means that if you have a world nearby
like Jupiter or Saturn, that has its own magnetic field,
they can influence each other,
and we can pick that up with a magnetometer.
So this is how Galileo was able to provide
tantalizing evidence of liquid water oceans
around Europa and a couple of other moons
in the Jovian system.
But life, as far as we know,
needs more than water.
There needs to be an energy source like the sun
or similar processes that create hydrothermal vents.
So when the Voyager mission flew past
Jupiter's moon Io in 1979
and witnessed volcanic plumes,
scientists were thrilled to confirm
that these frozen bodies were more active
than previously thought.
So we thought that the further out we got from the sun,
the less interesting the solar system would be.
Boy were we wrong.
Europa is far away from the sun.
It's five times farther than Earth.
And that means that it's much colder.
Europa should be frozen solid, but it's not.
Why is that?
Well, we think that there are two reasons.
The first is heat that's generated by
radioactive elements in Europa's core.
This is similar to how Earth's interior stays
molten and really hot.
As certain elements decay, they give off some heat,
but we don't think that could be enough.
The other thing that we think is keeping Europa warm
is something called tidal heating.
Now this happens because as Europa orbits around Jupiter,
its orbit is not a perfect circle.
Instead, it's a bit of an ellipse.
And that means when Europa is orbiting Jupiter,
sometimes it's a little bit closer,
sometimes it's a bit further away.
And so the moon actually goes like this
and that title flexing generates heat
just as if you were to, you know, rub your hands together,
you'd generate some heat due to that friction.
So we think that that also is helping to keep
Europa's ocean liquid potentially for a very,
very long time.
Tidal heating is also the reason
for the volcanic activity on Io observed by Voyager.
But there are other reasons for making Europa
the top priority.
While some moons in our solar system have many craters,
Europa has few.
And this means that the surface is probably very young
due to an ocean that causes the surface to warm and crack,
changing the landscape and erasing craters.
Based off of what we know of Europa now,
we know it has a liquid water ocean.
We know it has some building blocks
that could potentially be used
for organic molecules to make life.
And we know it has an energy source.
So all of these lines of evidence point towards
having the ingredients for life.
Not only that, but this intense tidal heating
could lead to hydrothermal vents
down at the sea floor of Europa.
And so this is why it's at the top of our list
to study as a world that could host life of its own.
Now all we need to do is get there.
Europa Clipper is prepared to launch in 2024.
We have really amazing cameras
that are gonna take higher-resolution images
than ever before.
We've got some imaging spectrometers.
These are instruments that will be able to tell us
what the composition of the surface is.
We'll have a magnetometer,
a fancy compass to be able to understand
more about Europa's interior ocean.
We'll even have a radar sounder
so that we can look for near-surface
water reservoirs too.
In addition to that,
we're going to have a few other particles
and fields instruments to try to understand
the plasma environment.
All of those ions that are zipping around
in the Jupiter system,
we'll be able to understand those
because they're important too.
Color and infrared cameras will map the surface
and search for hotspots where material from within Europa,
possibly the ocean, may reach the surface.
It will be the first mission sent
to specifically study a moon other than our own.
The mission will place the Clipper spacecraft,
which is longer than a basketball court,
in orbit around Jupiter,
where it will perform about 40 flybys of Europa.
Now ideally we would love to send Clipper
and go straight into orbit around Europa,
but the conditions in the Jovian system
don't make that the best option for us.
There's a bit of radiation that's right in
and around where Europa sits in orbit around Jupiter.
And while that's not necessarily bad for life,
in fact, it could make some molecules
and some ions that might be good for life,
it's not so good for our spacecraft.
So instead we're planning on doing flybys of Europa,
where we go in, we get our data,
we get out, we cool off for a bit,
send that data back to Earth, and it gives us
as scientists plenty of time to look over things
before the next pass.
The spacecraft may even be able to sample
particles high above Europa's surface.
During past Earth observations
and observations from the Hubble Space Telescope,
scientists have seen something that looks like
plumes of water or other material on Europa.
Clipper will be equipped with the right tools,
and will be able to fly close enough
to analyze those plumes if they do indeed exist.
This would be similar to Saturn's moon Enceladus,
where free sample from its ocean,
is actively venting into space.
Now, this would be really exciting for us
because some of the instruments aboard Europa Clipper
could collect some of those ice grains
if they're there or some of the gases
and be able to tell us
what they're made of
and help us get a glimpse of the composition of that ocean.
Although the main goal of Clipper
is to understand habitability on Europa,
not all of the questions regarding life
can be answered from flybys.
That's why NASA is proposing a follow-up mission
to launch in the next couple of decades
that could land on Europa.
The Europa Lander mission concept
is something that we've been developing
that could potentially visit a world like Europa
or another ocean world one day.
This concept could have some
type of legs to be able to stabilize itself
on a really treacherous terrain
and a lot of engineers are developing sampling tools
that could cut into very, very cold ice.
The European Space Agency
is also sending a probe in the next couple of years
called the Jupiter Icy Moons Explorer or JUICE.
It will spend at least three years studying Jupiter
and the habitability of three of Jupiter's moons:
Europa, Callisto and Ganymede.
The last of which was recently found
to have possible water vapor coming from its surface.
And there are even more ambitious proposals
to explore subsurface oceans in the far future.
There are even robotic snakes.
There's one that's called EELS,
the Exobiology Extant Life Surveyor.
We love our acronyms at NASA.
This is something that could slither down into cracks
or crevices where biosignatures might be hiding,
potentially protected from radiation.
So there are all sorts of exciting concepts on the horizon.
There are even like these hoppers
that could even take some of that water ice
and then melt it and use the steam to sort of puff
to bounce around, to go to different places.
Finding even microorganisms
would undoubtedly change our understanding of life
and the boundaries of the habitable zone,
the area around a star which we think could support life
as we know it.
Really it's caused us to change
our ideas for where we might look for life
and how abundant habitable conditions might be
in the universe.
Since many planets around other stars,
known as exoplanets,
are now thought to contain liquid water,
these expeditions may tell us more about
which of these planets are potentially habitable
and bring us closer to answering the age-old question
of are we alone.
Ever since we, as human beings,
first started to look up and wonder about stars,
about other planets, other worlds.
We wondered if we were alone.
You know, this universe is so vast, so immense, so amazing.
Are there other worlds that could be
more incredibly diverse beyond our wildest dreams
and have life of their own?
Or are we just incredibly, horribly alone?
I hope it's the first one.