Jovian planet with breathable oxygen atmosphere.

FtlIsAwesome

Could it be possible for a jovian planet to have an oxygen atmosphere breathable by humans?
Let's say that the humans live in blimp-like stations, and the jovian planet is small like Neptune to reduce the high gravity.

tiny-tim

Hi FtlIsAwesome!

But where would the oxygen come from?

And wouldn't it immediately react with everything in sight?

Vanadium 50

Remember, even Earth's original atmosphere wasn't breathable. We're all breathing plant poop. No plants, no O2.

phyzguy

I think it might be possible. Imagine a Neptune-like planet where Earth is. Cyanobacteria could evolve floating in the atmosphere like they originally evolved in Earth's oceans. Then they would generate the oxygen by photosynthesis. The big question is what about all of the free hydrogen, which a Neptune-like planet would retain, but which Earth is too small to hold.

FtlIsAwesome

Hmm. Maybe the hydrogen stays in the upper atmosphere??
Or we could have a smaller-than-Neptune jovian planet that doesn't retain the hydrogen.

Alternatively I abandon the natural breathable atmosphere idea and the jovian's air is terraformed.

phyzguy

If it's a smaller-than-Neptune planet that doesn't retain hydrogen, then it becomes a rocky planet like the Earth. I wouldn't call it "Jovian" any more.

Ophiolite

Just hope the magnetic field that seems to be a feature of Jovian planets is absent for some reason. Otherwise no serious biological molecule will remain intact for long.

Nicodemus

You're never going to have a Jovian planet that produces a breathable atmosphere for humans... not with that gravity, and not to mention that "breathability" isn't really the biggest anti-life factor on your average gas giant. Storms larger than our planet, and only a very narrow band where we could even experience proper gas-exchange in our lungs and blood really preclude breathing.

In a very real sense, the last thing you'd worry about on a Jovian planet is the quality of the atmosphere!

FtlIsAwesome

I don't think it would be necessary for a planet to need hydrogen to have a thick atmosphere composed of other gases, and therefore be classified as a Jovian, or mini-Jovian.


This should solve the problem - From Wikipedia:

Jupiter's broad magnetic field is 14 times as strong as the Earth's, ranging from 4.2 gauss (0.42 mT) at the equator to 10–14 gauss (1.0–1.4 mT) at the poles...

Saturn has an intrinsic magnetic field that has a simple, symmetric shape—a magnetic dipole. Its strength at the equator—0.2 gauss (20 µT)—is approximately one twentieth than that of the field around Jupiter and slightly weaker than Earth's magnetic field. As a result Saturn's magnetosphere is much smaller than Jupiter's...

Exojovians could have varying magnetic field strengths. Lets assume the planet in question has a magnetic field similar to Earth's.
By the way, how exactly do strong magnetic fields adversely affect living organisms?

So what you're saying is:
The high gravity will make it unlivable.
The storms would cause problems.
The band of breathable altitude is narrow.

I will probably use this idea for the story I'm working on, and I already have artificial gravity in it, so this can be the solution for many high-gravity worlds. In most scifi I've only seen artificial gravity used for ships, I've always wondered why they never use it on the surface of a planet.
The storms may be a problem, but some jovians may have less powerful storms. Jupiter has strong lightning strikes, but could other jovians have less powerful lightning strikes?
As for the last one, the blimps could maintain their altitude at the breathable level.

qraal

Huh?

Chalnoth

I don't think so. One problem (among others people here have mentioned) is the abundance of the various elements. It's very, very easy to make a big planet that is mostly hydrogen and helium (because most of the matter in the universe is hydrogen and helium). It isn't so easy to make a big planet that is mostly made up of elements like nitrogen, oxygen, and carbon: these aren't quite so common, because they are mere stepping stones to the most stable element, iron. When the heavier elements like oxygen and carbon are thrown out into the galaxy as a result of a supernova, they tend to come along with other heavy elements like iron. So it would be very, very difficult to get a planet that has lots of oxygen, but not also a lot of rock to go with it. Perhaps not impossible, but very difficult nonetheless.

qraal

The short answer is: No.

The long answer is more complicated. Planets could form large oxygen atmospheres from solar radiation (EUV and solar-wind) decomposing an ocean - Venus is believed to have had an oxygen atmosphere perhaps a hundred times thicker than Earth's as its hydrogen was lost en masse to space and this could happen to an Ocean planet. BUT it would be much too hot to be breathable.

There are Earth-like models of Ocean Planets, but they aren't Gas Giants as such. Such planets would undergo hydrogen-loss and build up large, thick atmospheres of nitrogen from ammonia photolysis. Oxygen from decomposed water would probably react with any methane and form carbon dioxide, huge amounts dissolving and precipitating in the ocean. Alternatively hydrogen and nitrogen could coexist, as they are believed to have done on the early Earth.

What isn't possible is a build up of oxygen when there's lots of hydrogen around - the two react too readily for large amounts of both. Nitrogen will coexist with either, but hydrogen (and methane) won't last around oxygen. Either hydrogen dominates and any oxygen reacts with it to make water, or there's a net hydrogen loss so free oxygen can build up.

There is one other option. A gas giant could be engineered with a breathable atmosphere. Take Neptune or Uranus - both contain large amounts of carbon. Wrap the bulk hydrogen/helium of a Gas Giant in that carbon, reformed into a shell of diamond. Then place your breathable habitat above that.

Nicodemus

Yeah, what I was trying to say is more what qraal is getting at with more skill and knowledge. Jovian planets are not hospitable to human life, regardless of the technology employed. I mean, these are people in your story right?... so, why are they colonizing the human equivalent of hell, given so much tech?

FtlIsAwesome

This is something I should have noticed before:
Equatorial surface gravities (g)
Jupiter 2.528
Saturn 1.065
Uranus 0.886
Neptune 1.14

Source: Wikipedia

I won't have to worry about surface gravity anymore. And I can even make it like Saturn and give it rings!


As for the other problems, you are saying that it is the leftover hydrogen and helium, and the high temperature?
Humans can breathe helium, but an oxygen-helium mix would probably seperate into low and high altitude bands, respectively.
The heat can be managed by placing it further from the sun. If were talking about heat generated by the interior, hmm. Ideas?

I would like this planet to be as habitable as possible prior to people visiting it.
This type of planet need not be common, as the minimum I want is one, ie. explanation of unlikely planet as one-in-ten-thousand.

This how I came up with the idea: research station in low-orbit over gas planet-->blimp station in atmosphere-->hey, let's make the atmosphere breathable! that'd be so cool!

Nicodemus

If I had to fashion a colony, while I can't say that qraal's ideas aren't ficitonally possible, I'd just mash together some small rocky planets, and essentially build an Earth 2.0. It seems easier to build a colony and deal with that, than it would be to harness forces that even a suicide probe can't handle.

I like qraal's inverted Dyson Sphere though... I like it a lot.

FtlIsAwesome

The blimps would float at roughly 1 atm altitude. Even with materials that can withstand higher pressures, people can't.
Unless your talking about heat, lightning, and/or storms. Hmm.

But actually building a planet is pretty interesting. Something for another thread.

Nicodemus

OK, if we're going full sci-fi, I'm in for that. Hell, I don't even mind the improbability of qraal's solutions if it made sense within the narrative.

I wonder... could you build a planet with a sufficiently hot (radioactive and literally) core, and the proper tectonics for a colony? Could you even "cook" it so that it generates its own atmosphere, much like Earth?

Maybe something like Larry Niven's "Fleet of Worlds" from the Ringworld series would make sense as well. As for blimps, I'd still say that's one hell of a narrow margin, and I'm not sure that breathable air would be found in that band.