/sci/ - Science & Math

[Anonymous No.11856828]

Writing a sci fi novel, would an ocean planet full of water be predisposed to an atmosphere with oxygen?

[Anonymous No.11856834]

>>11856828
it’s possible but not likely

[Anonymous No.11856839]

Oxygen in Earth's atmosphere came from plants photosynthesizing, it wasn't there to begin with.

[Anonymous No.11856840]

It depends on where the oxygen comes from.

[Anonymous No.11856844]

>>11856828
I guess it's prerty much guarranteed as the hydrogen escapes and leaves oxygen on the planet. So oxygen atmosphere could be expected as long as the planet is small enough to allow hydrogen escape. Not my field though so wait for others to confirm.

[Anonymous No.11856845]

>>11856828
If you mean if it doesn't have life on it to generate that oxygen, then it is possible. The ocean planet would have to be close enough for the water to be liquid so some of it can evaporate to become the planet's atmosphere. From there, the planet's star's UV rays will 'crack' the water in the atmosphere into hydrogen and oxygen. Assuming that the planet isn't incredibly massive, then the hydrogen will escape into space leaving behind an atmosphere of mostly water and oxygen.

An issue from this is that this would mean that the planet is slowly losing it's water. Over time (in geological time scales) the planet would lose all of it's water. If the type of star in your novel isn't set in stone, then pick a type of star that doesn't produce lots of UV rays (smaller than type G). That way your ocean planet can last for as long as you need to tell your story.

[Anonymous No.11856851]

>>11856839
Plants can only convert CO2 to oxygen, which would have insignificant unless the atmosphere was absolutely massive, as the oxygen gets absorbed by rocks and you run out of the CO2. You need the hydrogen escape and water.

[Anonymous No.11856890]

>>11856828
Sure. Algae are the main source of oxygen. Oxygen from photosynthesis killed early life.

[Anonymous No.11857478]

>>11856890
>>11856845
>>11856844
It does have ample plant-ish life, but it's made from silicone and get it's nutrients via motion.

What type of star would you recommend? The only thing set in stone is the plant rocks.

[Anonymous No.11857508]

>>11857478
>What type of star would you recommend?
Larger than class M, because planets close enough to a class M star to have liquid water would also be close enough to be tidally locked which isn't favorable for an ocean planet. Smaller than class F, because any larger stars would put out significant amounts of ultraviolet light which would crack away the oceans in a relatively shorter time. Ideally class K in my opinion.

What kind of ocean planet are you working on? Is it like Earth, where it is mostly rock and iron but completely covered in water? Or is it like Ganymede or Europa, where water makes up a significant portion of the planet's mass?

[Anonymous No.11857544]

>>11857478
>made from silicone and get it's nutrients via motion
Can you tell more?

[Anonymous No.11857547]

>>11857508
Why not place our water world in a locked orbit around a large brown dwarf having a large magnetic field, larger than Jupiter's, and have these in an orbit around a class F? That way you can have a lot of blue green light to reach deep into the ocean and retain a strong shielding atmosphere.

It would also be an interesting view.

[Anonymous No.11857614]

>>11857544
Basically they derive nutrients via the motion of the waves. They operate on a large anchored stalk below water with long tethers full of "leaves" that the tide pushes and pulls. This gives them the energy they need to function.

There's fauna that get by via eating them, also silicone based.

[Anonymous No.11857621]

>>11857508
>What kind of ocean planet are you working on? Is it like Earth, where it is mostly rock and iron but completely covered in water? Or is it like Ganymede or Europa, where water makes up a significant portion of the planet's mass?
I was thinking more earth like, with oceans similar but no big landmasses. There's isolated little islands and caverns, so it needs a big rocky crust.

[Anonymous No.11857897]

>>11856828

https://ocean.si.edu/ocean-life/plankton/every-breath-you-take-thank-ocean

[Anonymous No.11857901]

>>11857621
>isolated little islands
You could use pumice:
>In 1979, 1984 and 2006, underwater volcanic eruptions near Tonga created large pumice rafts, some as large as 30 kilometers (19 mi)[citation needed] that floated hundreds of kilometres to Fiji.[9]

[Anonymous No.11859120]

>>11857901
Well it's fairly important that there's an extensive cave network.

The general idea behind the planet is that the crystal plant things actually developed psychic powers to survive after a good chunk of them get stuck inside a cavern. They survive via a symbiotic relationship with a species of bat-like creatures, hijacking their bodies and using them as proxy forms. They allow the creatures to nest around their crystalline form, wherein the heat given off by them helps hatch their eggs.

They come into conflict with post humanity when they try to set up colonies upon the planet and end up being mentally controlled as better proxies.

[Anonymous No.11859127]

There needs to be a worldbuilding general.

[Anonymous No.11859644]

>>11859120
>Well it's fairly important that there's an extensive cave network.
You can easily carve out caves in a pumice raft. And we can have algae in the world building that coat and waterproof the pumice so it doesn't sink.
>The general idea behind the planet is that the crystal plant things actually developed psychic powers to survive after a good chunk of them get stuck inside a cavern.
Crystals are too stable for a dynamic life form so we are leaving hard sci fi then. Why does it have to be crystalline?
>They survive via a symbiotic relationship with a species of bat-like creatures, hijacking their bodies and using them as proxy forms. They allow the creatures to nest around their crystalline form, wherein the heat given off by them helps hatch their eggs.
Does this plot need a water world?
>They come into conflict with post humanity when they try to set up colonies upon the planet and end up being mentally controlled as better proxies.
Not sure what you intend with post humans, but present day humans have very limited use for a water world.

[Anonymous No.11859663]

>>11859644
>Crystals are too stable for a dynamic life form so we are leaving hard sci fi then
It's not intended to be super hard sci fi, though I try to make it at least a bit harder than space fantasy and think this shit out.

I chose crystals because I intended for the major distinguishing physical characteristic of the psyker post-human race being the fact they have crystals growing from their forehead that's implied to be linked to their powers. It can be anything, really, so long as it's not conventionally organic.
>Does this plot need a water world?
The plot needs the aliens, because it demonstrates to the villain that mind control via psychic powers is possible. Before the discovery most psykers can only manipulate things externally.
>Not sure what you intend with post humans, but present day humans have very limited use for a water world.
Humans in this setting are really divided. Takes place in another galaxy after countless generations, where humans arrived via generational ships. Each post humanity race is the result of that prolonged evolutionary bottleneck aboard the ships.

The psykers are unique because their ship records cut off halfway through, where they encountered something that fucked them all up. They're integral to the setting since there's no true FTL, so people get by via worm holes. Psykers can create wormholes.

[Anonymous No.11859665]

>>11859663
Due to this division in the post humanity, every potentially valuable planet is in hot demand. In particular ones with life, which are insanely rare.