This morning, the Cassini spacecraft formerly at Saturn plunged into the atmosphere of that
world due to the spacecraft being nearly out of fuel.
This was done deliberately, because leaving the spacecraft in orbit would expose the pristine
moons of Saturn to an eventual collision and with that the potential for contamination.
Cassini was an extremely successful mission, yielding data that will be useful in understanding
the Saturn System for decades to come.
There are a lot of interesting moons at Saturn, that’s actually an understatement, but one
in particular stands apart from anything else in the solar system.
It’s Titan, and with that moon comes the possibility of a completely different kind
of surface biosphere than we have here on earth.
But it isn’t based on water.
When talking about life in the universe there is a kind of bias towards liquid water.
It’s a justified bias, we know that life can arise from organic chemistry with water
as a solvent.
It happened here, and it works really well, seemingly better than any other liquid possibility.
And while water is very well suited in many ways to life, especially in light that it’s
quite common in the universe, there are other options.
There are a number of possibilities there that I’ve covered in other videos on this
channel.
But perhaps the most interesting are the hydrocarbons, which exist as a liquid on the surface of
Titan and perhaps a similar state of affairs happens commonly in the galaxy at large.
In other words, studying Titan may give us insights into whether life can arise at all
on liquid hydrocarbon exoplanets.
Even better, we may find life on Titan.
And if that’s the case, then life of that sort could be quite common in the universe.
Unfortunately, it’s still uncertain just what to look for when searching for signs
of this kind of Methane based life.
It would depend on how and what it metabolizes, and we’re still early in the game in envisioning
that.
And it’s also worth asking whether life on that model could ever develop complexity,
a very cold or high pressure environment is needed for this kind of hypothetical biosphere
and that introduces much slower metabolisms into the mix of just what is possible.
But, if it is indeed possible for hydrocarbon life to exist, then it would open up an entirely
new habitable zone around stars, one much further out and far colder.
This is useful when looking at systems based on red dwarf stars, which have taken a lot
of hits lately as to whether they can host earth-like worlds.
The problem there is that a water habitable zone must be very close in to the star exposing
any planets to high levels of radiation, especially early in the star’s history.
Not so much with the hydrocarbon, or methane habitable zone.
It’s much further out from the star, as Titan is in comparison to earth.
But if you placed a Titan-like planet in a red dwarf system, there would be advantages
and disadvantages.
For example, Titan’s thick atmosphere is transparent to red and infrared frequencies,
which red dwarves produce a lot of.
That could warm the planet and extend the methane habitable zone even further.
But there’s also a lot of ultra violet light, so an opposite effect could occur where the
UV creates hazier conditions than what Titan has.
This could in turn cool the planet, so the exact individual circumstances within a star
system will probably play a part on how habitable these worlds are, assuming liquid hydrocarbon
life can even exist.
But we do know that liquid water life can exist, which opens up a further possibility
with the red dwarfs, these are the ice shell worlds that really aren’t beholden to habitability
zones at all.
In fact, planets with oceans under ice could be anywhere, even rogue planets located in
the depths of deep space.
But that’s for a future video.
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently wondering about hydrocarbon
alien scientists dismissing earth as uninhabitable because it’s so warm that it’s bathed
in molten lava water and be sure to check out my books at your favorite online book
retailer and subscribe to my channel for regular, in-depth explorations into the interesting,
weird and unknown aspects of this amazing universe in which we live.