Where, except for on Earth, could we find life in the Solar System?
Well, with yet another announcement today, I’m beginning to think almost everywhere. But this is too glib an answer. Let’s put some reality into the answer to this question.
As noted in my previous post, we’ve assumed for a long time that life requires oxygen. But there’s been the recent suggestion that life could exist in methane seas of Titan. See my previous post on this subject.
There have been suggestions that subsurface oceans on icy moons could harbour basic forms of life. Two moons known to have such oceans are Europa (Jovian system) and Enceladus (Saturnian system). The recent buzz in the news is it’s been proved that Enceladus has hydrothermal activity. See here for details. It’s one step closer to proving the existence of life.
Other moons that have known active cryo-volcanic activity are:
- Triton (Neptune system – see my short story Guard Cat here)
- Charon (Pluto system)
- Ganymede (a recent announcement confirming it has a salty ocean here)
Other moons where there are potential indications that life might exist are:
Moons that have clear evidence of cryo-volcanism in the past, but no obvious signs of it now, are:
- Ariel (Uranus system)
- Miranda (Uranus system)
These may still harbour small pockets of subsurface water where life could exist.
But cryo-volcanism does not have to be the only mechanism to sustain life.
The planet Venus used to have a more friendly atmosphere until it got overheated. Even so, there is a shell of atmosphere surrounding the planet that is very similar to our own here on Earth. Could life somehow have learned to float in this atmosphere, much like fish on out sea? Of course it would have to be microbial and nothing complex.
Then there’s Mars. The recent confirmation that there is water, albeit now locked in as ice, suggests life might have had a chance to develop when it was warmer. You would think it could no longer exist, but I’m far from sure. See my story: A Fate of Dust for the how and why it could still exist in small pockets there.
And before I forget the dwarf planet Ceres in the asteroid belt which may still have a subsurface layer of water, kept liquid due to the pressure it is under. See here for details. Maybe the Dawn probe will give us more insight on this situation soon!
All in all, these data should be combined to be the basis of an easy approximate formula to identify when and where life could exist. This could be based on the amount of tidal heating or eccentricity of the orbit, density of the body and maybe some other key parameters.
It would certainly help science fiction writers to design their solar systems of the fictional futures.