Question Explore Europa and Titan for life

[Starfleet Admiral]

Obviously Europa and Titan are prime candidates for the discovery of alien life forms in this solar system. Humans should make every effort to explore these moons in our quest for understanding the universe.

 

[Vincent Peri]

I heard Saturn's moon Enceladus is a prime candidate too.

 

[Meteoric Marmot]

From an engineering standpoint, Titan is the best choice because it has an atmosphere that the Huygens probe already successfully used for aerobraking. Enceladus and Europa have no atmosphere so you have to carry fuel to brake and land. Then you're faced with many kilometres of ice to tunnel through before getting to the interesting bits. Biologically, the scientists so far consider the ice moons as being more likely to harbour life. If the money were avaiable, we should visit all 3 -- and quickly because I'm too old to wait 20 years.

 

[Catastrophe]

I used to think that one or more outer moon might be suitable for colonisation (not terraforming).

I mistakenly thought that, as the Sun expanded in a few billion years time, the outer SS would warm up and maybe offer a future home for the human race (if they get beyond the next 100 years, that is).
Of course, I forgot that the giant planets would lose their hydrogen, helium, methane, water, etc., and shrink to not much more than Earth's current size. And their 'enticing; moons would not only offer a water surface for any descendants, but would escape their planet's diminished gravity, and wander off as rogue moons.

But OP does not mention colonisation or terraforming, only suggests Explore Europa and Titan for life. This is a totally different matter. These moons do not rely on the Sun for heat - that is produced by gravitational friction. In fact, Io is probably already too hot.

So, imho, OP is correctly suggesting that these (plus Enceladus) may be ripe for investigation, but for simple life forms, probably microorganisms or plants.

Cat

 

[Helio]

Enceladus seems very inviting. Flying through its plumes reveals several things, including organics. There does seem to be reasonable evidence for cracks from surface to ocean. More here.

 

[Catastrophe]

Incidentally, I have found a very good (imho) book on Titan, details as follows:

"Titan Unveiled" by Ralph Lorenz and Jacqueline Mitton published by Princeton University Press 2010. US$ 19.95 265 pages..

Cat

 

[voidpotentialenergy]

I think Titan will be a very interesting place.
Billions of years of lakes and atmosphere are a recipe for life of some format.
We might need to be very creative in detecting it though since it's a very alien place and life will probably be very alien.

Drilling though many KM of ice on any ice moon is going to be problematic unless we find a crack near the surface.
ice/water pressure will be crushing if we have to drill 10 km or more to get to water.
Most of the ice moons will have far more than 10k of ice.
Even if we drill through the ice we drop into extreme water pressure more than the bottom of Earth's ocean on most of them.
Microbial life a good chance but getting to it a teach problem.
Lots of ice moons to explore for life for sure.

 

[Catastrophe]

Some interesting background:

Titan Ralph Lorenz - Google Search

Cat

 

[Helio]

For Enceladus, there seems to be a crack in the proverbial wall that may allow us into those inner oceans.

"Summary: Our analysis provides critical information for the ongoing feasibility study of a robotic mission to sample at, or descend into, Enceladus vents, as one of the major challenges of such mission is the dynamic pressure. The results are preliminary, but within the scope of the assumptions made we find that the upper limit dynamic pressures are not insurmountable. They point us in the direction of anchored robots with low drag structures" [my underline]

Paper here.

 

[Helio]

Drilling though many KM of ice on any ice moon is going to be problematic unless we find a crack near the surface.
ice/water pressure will be crushing if we have to drill 10 km or more to get to water.
Most of the ice moons will have far more than 10k of ice.

Enceladus may be the exception to this, hopefully. Some estimates are as low as 1 km for the crust thickness at the southern pole. It's diameter is only about 500km, and a surface gravity about 1/10th ours, so I'm curious if the water pressure would be too extreme.

 

[Catastrophe]

CARE: This (Dr Lorenz) interview starts about half way through. Full screen via bottom right button.

It might start in the right place, otherwise use slider.

1:08:31
Weekly Space Hangout: November 18, 2020, Dr. Ralph ...
YouTube · Weekly Space Hangout
19 Nov 2020


Cat

 

[voidpotentialenergy]

Enceladus may be the exception to this, hopefully. Some estimates are as low as 1 km for the crust thickness at the southern pole. It's diameter is only about 500km, and a surface gravity about 1/10th ours, so I'm curious if the water pressure would be too extreme.

I agree it will be one of the few exceptions.
A great moon to test out the idea since it seems to have vents active so testing might be possible right on the surface at a vent.

It and Titan i think will be the best places to try looking for life signs.

I'm not holding my breath that Titan will have any life.
If it does though it's sure to be a different format than Earth or so evolved to Titan it's difficult to find similarities.

We might have even easier markers for life on a few of the ice moons.
Red streaks in the ice.
Artic Earth red streaks are usually associated with microbial life.
Testing it at the surface might tell about life below on ice moons without drilling down X-KM.

 

[Catastrophe]

Sunlight is, of course, irrelevant. Warmth comes from frictional heat. But primitive life could develop in liquid water oceans.


Cat

 

[Helio]

Sunlight is, of course, irrelevant. Warmth comes from frictional heat. But primitive life could develop in liquid water oceans.

That may even be how abiogenesis happened on Earth -- from the ocean's dark thermal vents.

 

[Catastrophe]

Helio, would not the thermal vents depend ultimately on internal heating - either nuclear or frictional or heat of accretion)?

Cat

 

[Helio]

Helio, would not the thermal vents depend ultimately on internal heating - either nuclear or frictional or heat of accretion)?

If there are thermal vents, it's likely they will be regular in flows to produce a long-term stable environment, which is critical for any chance for sustaining life. Chemeicals from these vents I expect will also be a critical part of the life equation as well.

Accretion offers the chemical part of the equation but are too violent to offer any stability, I would expect. Darwin knew that an order of a billion years would be needed for any real chance of evolution to produce amazing advancements in order. He called Lord Kelvin an "odius sceptre", IIRC, ( ) for his 100 million year age for Earth -- too young a planet for life to evolve to current levels.

 

[Catastrophe]

Yes, of course, too much heat is destructive - vide Io. But, as you know, heat results from movement of molecules, and molecules need to get around to hook up and make more complex molecules. Too much heat (motion) and they can knock bits off each other - too little and they meet too few potential partners.
Hence we might suggest three phases, better known as Goldilocks and the three bears (who liked porridge).
Phase 1 was too hot and complex molecules could not form.
Phase 2 was just right and primitive life could form.
Phase 3 was too cold and no new complex molecules could form.
Fortunately, Phase 2 quite often lasted a long time and life got a chance to develop and take hold.

Cat

 

[Helio]

Yes, of course, too much heat is destructive - vide Io. But, as you know, heat results from movement of molecules, and molecules need to get around to hook up and make more complex molecules. Too much heat (motion) and they can knock bits off each other - too little and they meet too few potential partners.
Hence we might suggest three phases, better known as Goldilocks and the three bears (who liked porridge).
Phase 1 was too hot and complex molecules could not form.
Phase 2 was just right and primitive life could form.
Phase 3 was too cold and no new complex molecules could form.
Fortunately, Phase 2 quite often lasted a long time and life got a chance to develop and take hold.

Nicely put, and the "proof is in the putting" (or is it porridge?).

We had some abiogenses discusions a while back that presented articles explaining some of the advantages of life forming in certain vents, vs. tidal zones. The energy balance at a cellular level was found favorable in one type of vent, which was interesting to read about.

Once liquid water (ie oceans) formed, they would have allowed for a constant region of ideal temperatures (whatever these might be) as long as the vent flows were fairly stable in flow rate and temperature. I suspect this might be possible on Enceladus given the heat comes from tidal effects with Saturn, which doesn't change except on million-year time scales.

 

[voidpotentialenergy]

Any of the ice moons could have a diverse set of life under the ice.
Billions of years of microbes adapting for an advantage and the sky is the limit.
Or it might be just water, or only very few select primitive microbes.
Any format of life would be an eye opener about life at least in our solar system.