Few worlds in our solar system are as compelling as Saturn’s icy moon Enceladus.
Small enough to nearly fit into the United Kingdom, this tiny, yet fascinating world
is covered in intriguing features, the most noticeable being its bright white surface,
and those enormous fractures that crisscross its frigid terrain.
But it's not just its surface where incredible things have been discovered,
below its frozen crust, a secret subsurface ocean
exists that harbours the right ingredients necessary for life.
So much of Enceladus still remains a mystery, but by using the stunning images captured by the most
recent spacecraft to visit the Saturn system, we can peel back the layers of this tiny world,
we can take a closer look and observe its fascinating features like never before.
So why is it so bright? What is causing those enormous fractures? And what other secrets
have we discovered during our time exploring the snowball-like moon, that is Enceladus?
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Before the Cassini spacecraft arrived at Saturn this was the best close-up image we
had of Enceladus, captured by the famous Voyager 2 in 1981. It revealed the icy moon to be one of
the most active worlds in the solar system, with one side being heavily cratered while
the other side is fresh and smooth. Indicating huge differences in the ages of the terrains.
Jump forward 23 years and NASA's Cassini spacecraft arrived at Saturn,
capturing exciting new images of Enceladus in far greater detail. Allowing us to see so much more.
Such as the enormous tiger stripe-like features that snake across its South Pole.
Highlighted in blue in this false colour image, the tiger stripes
are one of the most distinctive and puzzling features seen on Enceladus.
They are parallel and evenly spaced, about 130 kilometres long and 35 kilometres apart.
What makes them especially interesting, however, is that even right now, as you are watching this
video, they are erupting with icy material, a bit like geysers we find here on Earth.
Water ice from the ocean below spews into space through these stripes or cracks,
as can be seen in these incredible images.
It was discovered that Enceladus experiences gravitational flexes as it orbits Saturn,
which deforms its shape, causing the ice sheets at
the poles to be thinner and more susceptible to splitting open.
Because of the tidal effects of Saturn's gravity, the cracks also stay open, constantly widening and
narrowing, preventing them from closing up and causing the ocean below to spew out and
freeze in the near vacuum of space. Most of which falls back to the surface like snow.
Enceladus is shrouded in a thick layer of snow that varies in depth across its surface.
In most places, it is hundreds of meters deep, but in some areas, it is estimated to be as deep
as 700 meters. That's deep enough nearly cover the world's tallest building, Dubai's Burj Khalifa.
How this much snow, which more accurately is called regolith by scientists,
can build up on Enceladus is a bit of a mystery.
Because if the plumes of icy material coming from the tiger stripe-like fractures were
always spewing out what they are today, it would take an estimated 4.5 billion years,
the entire age of the solar system, to deposit that much on the surface.
Even then, it would have to be extremely fluffy snow, but it is thought that the
ice crystals on Enceladus are only a fraction of a millimetre in size,
roughly a micron or two across, even finer than talcum powder.
Scientists think it is unlikely that the plumes of icy material started as soon as the moon formed,
and then never changed. Which must mean that the plumes had far more
active moments in the past. Producing far more material, that over a long period of
time eventually settled and created these extremely deep snow drift-like regions.
This constant coating of clean snow also makes Enceladus the
most reflective white object in the solar system.
But it's not just the surface of Enceladus where this blizzard of frozen particles end up,
because it also helps to contribute to Saturn's magnificent rings.
Called the E ring, this faint, wispy section of Saturn's ring system is actually being
created by Enceladus, as it moves through space and sprays material along its path.
The larger particles fall back to the surface as snow as we have already seen,
while the smaller particles travel higher,
escaping Enceladus and forming the enormous doughnut-shaped ring that it exists within.
In this incredible image captured by Cassini, Enceladus can be seen at work,
as streams of ice spray out into space, forming a trail of long tendrils.
And it's not just Enceladus where the icy particles end up,
neighbouring moons have also become coated in its snow. Such as parts
of Tethys which are brighter due to its path through the E ring.
The trojan moons Telesto, Calypso, Helene and Polydeuces are particularly affected
as their orbits move up and down the ring plane. The result as can be seen in these
images are that their surfaces are coated with icy material that smooths out their features.
It was discovered that the plumes gushing from Enceladus are blasting out at around 400 meters
per second, and it appears to be erupting continuously with no signs of slowing down.
Because these magnificent plumes are being supplied by the mysterious ocean below,
it also provides an opportunity to study it. Offering a kind of
window into what is happening below the ice.
Between 2008 and 2015, Cassini actually flew through the plumes
multiple times and analysed the material, and incredibly it detected most of the
ingredients required for life. Along with evidence that Implied the ocean is salty.
It even discovered that the E ring, which is mostly made of ice droplets,
also contains certain nanograins that can only be generated where
liquid water and rock have interacted at temperatures above 90 degrees Celsius.
Indicating that hydrothermal vents deep beneath the frozen outer shell
of Enceladus are warming its ocean. Much like we find in our oceans here on Earth.
So with all the right conditions, could there be life below the ice of this frigid moon?
Hopefully, future visits will answer that, as several robotic missions have
been proposed to further explore Enceladus. However, none have been confirmed as of yet.
Enceladus could well be the most exciting place we have explored beyond Earth so far. Below
its snowy crust may be an environment where life flourishes. But even if there isn't life there, it
is still a fascinating moon that deserves further studying and hopefully we will be receiving new
images and data from this never-ending winter world sooner rather than later.
I hope you enjoyed this video, if you did then why not watch some more, there is
plenty of cosmic content to choose from. Thank you for watching and I'll see you next time.