Hi everyone. My name's Sheila Kanani and today I'm going to take you
from Earth to Saturn on board the Cassini spacecraft.
And we're going to be looking at Saturn and a couple of Saturn's moons as well.
The Cassini spacecraft is a NASA and ESA joint mission
It was build in the late 1990's.
It cost about $5bn, so it was really expensive.
But the information that it's been giving back about the Saturn system
has been so incredible that it's been worth every penny.
This is a time-lapse movie of Cassini being built in NASA's JPL.
And as you see Cassini in its entirety, you can see it's one of the biggest ventures NASA has
ever done
Here's a person here for scale.
It's actually about as big as an American school bus.
The huge dish on top of Cassini there
sends the information back home, just like a satellite TV
on the roof of your house
and this big gold thing here is the Huygens probe. Now the Huygens probe actually landed on
Saturn's moon, Titan
and gave us information for about 18 months.
Cassini's really interesting. It's got 12 instruments on board
and these instruments all do different things.
There's a dust analyser, there's cameras, there's infrared cameras,
there's a magnetic field data analyser,
and there's a Cassini plasma spectrometer.
The Cassini plasma spectrometer is really important to me because
my lab, Mullard Space Science Laboratory, which is the Space & Climate Physics Department
of UCL,
actually built part of the Cassini plasma spectrometer,
and that's about here on this screen.
Now we built the electron spectrometer.
That's it there in a vacuum chamber in the lab,
and if you rotate it by 90 degrees and cut it in half,
this is a schematic of the electron spectrometer.
The electrons fly in here,
and they're detected by panels down here.
Now with the electron spectrometer and all the other instruments on board Cassini,
we can find out so much more about Saturn, its rings and its moons and the whole Saturn environment.
This is one of my favourite pictures from Saturn.
And you might think it's kind of boring because the planet itself is in shadow
and that's because the Sun
is behind the planet, so
the face of it is all black, but that's really cool because it's actually lighting up the rings,
and you can just about see the largest ring, the E-ring
here and you can see how far out the rings actually extend from the planet.
Now if you zoom in on the top right-hand corner,
you can see the rings here again
and here,
you can see this tiny little blue dot.
And it looks pretty insignificant, but if we zoom in on it there,
that is what the Earth looks like from Saturn
so it's a pretty humbling experience, seeing our planet
from someone else's perspective.
Let's look at the moons now. Titan, Saturn's biggest moon,
is bigger than Mercury,
bigger than
the planet Mercury,
and it's got its own atmosphere.
It's obscured in these thick orange clouds, but
if we look at it in different instruments,
visible light and infrared, we can actually learn a lot more about Titan itself.
Titan's actually got liquid lakes on it.
Not liquid water, unfortunately, but liquid methane. And this sounds a bit
strange but it's very interesting
because the Earth is thought to have had liquid methane lakes on it
about 5 billion years ago.
So if we could go back to Titan in 5 billion years' time,
who knows? Maybe there would be life.
Another really interesting moon
is Saturn's moon, Enceladus. It's about 500km wide,
so about the size of the UK.
And it's actually covered in a water ice crust.
This picture was taken from a fly-by,
only 50km from this
moon's surface.
And you can see these huge structures
in the water ice.
Now one of the reasons I like Enceladus is because it was named
after the Greek
Gigante,
Enceladus,
and he was actually killed by the goddess Athena.
He was buried underneath the island of Sicily
and it's thought that when he gets angry and shakes,
he shakes the whole island
and the people on the island believe that that is when
Mt Etna's going to erupt.
the reason I like that is because if we look
at a photograph of Enceladus the moon,
you can see these huge cracks
and they're not volcanoes, but they are cracks in the water ice.
And when they rub together,
the moon actually lets off liquid water into the Saturn system.
This incredible photograph here
shows the water plume here of Enceladus letting go liquid water into
the Saturn system.
This is really cool because
one of the models of this water ice being let off into the Saturn system
involves a saline ocean underneath the ice crust.
A saltwater ocean is really exciting because that could mean plants
or maybe even life
underneath the surface of Enceladus.