Page 67 - All About Space 68 - 2017 UK

Life but not as we know it

NEPTUNE
This Voyager 2 image shows the clouds on
Balloon life forms with Neptune, as they travel through the winds
much like the floaters would do
antifreeze systems

Neptune is the farmost known large planet in the Solar System, and
therefore the coldest, with a surface temperature of 72 Kelvin (-201
degrees Celsius). This ice giant is 17-times more massive than our Earth,
with the most ferocious winds in the whole Solar System, reaching speeds of
2,200 kilometres per hour (1,300 miles per hour).
This is arguably the most inhospitable environment in the Solar System,
and no form of life as we know it would have a chance of surviving here. The
closest thing that astrobiologists can think of is a ‘Floater’ similar to Jupiter, but
with certain adaptations to survive a different surrounding.
With the freezing temperature of Neptune, the Neptunian floater must have
compounds in its system with an extremely low freezing point. The most likely
candidates are a series of amine compounds – which is a derivative of ammonia
– that is naturally an antifreeze.
Another important aspect of survival is its buoyancy, as Dartnell explains:
“You’d need to remain buoyant in the atmosphere, just in the same way you’d
need to with Jupiter.” This buoyancy is what will stop the life form from falling
to extreme pressures, and eventually, its demise.
This life form must be enormous in size, as it needs to absorb as much
precious sunlight as possible. However, with winds whisking the floater around
at such high speeds, it would have to leave the sunlit area soon after its arrived.
Not to worry though, as doing one lap of Neptune – going at its wind’s speed –
would only take seven hours. This creature would only have disappeared a few
hours before it returned back to a sunlit area. © NASA/JPL, © Tobias Roetsch
Even if this is hypothetical and very imaginative, it is still the best way for
someone to think in a field that requires so much creativity and originality.

ENCELADUS

Giant tubeworms

thriving off the

hydrothermal vents

Moving to another satellite of Saturn now, there is one moon that astrobiologists
Deep in the Pacific Ocean
have discovered to be comparable to Europa. “Enceladus and Europa have probably
are giant tubeworms,
thriving off hydrothermal got similar environments, so life would probably need to be less extremophilic
to survive there,” says Dartnell. Enceladus is also much smaller in comparison to
vents with no sunlight
Europa, being roughly twelve times smaller.
In 2005, the Cassini spacecraft observed the frozen surface of Enceladus, and
caught an unlikely event occurring. In the southern region of the moon, plumes of
ice appeared to be erupting from the surface, like the geysers we know on Earth.
A slight change of course for Cassini was then initiated, and the spacecraft threw
itself through the plumes to investigate further. The results showed that these
plumes were grains of silica, which helped identify the interior composition of
Enceladus from which it originated.
From these results, scientists concluded that there is a subsurface ocean, similar
to Europa. This begs the question, what on Earth could arise in the depths of an
© NOAA, © NASA/JPL/Space Space Institute on Earth, the magma towards the core heats the seafloor, exposing a mineral-rich
ocean whilst being heated by the interior? The answer is hydrothermal vents.
These vents are so deep down on the seafloor that no sunlight touches them. But

vent for different forms of marine life to thrive.
“They may be different, but all hydrothermal vents tend to have not just bacteria
and other microorganisms, but large, multicellular, complex organisms as well,”
says Morgan Cable, an engineer for the Cassini mission and research scientist
for NASA’s Jet Propulsion Lab. Such complex organisms could include giant
tubeworms, which survive in equivalent conditions on the floor of the Pacific.

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