In the atmosphere, how do you meaningfully keep that bubble around you?

Yes. This.

I hope that we piggyback on Mars exploration for building infrastructure on the Moon.

The Moon is a much better target for a first self sustainable colony and also could become economically interesting.

There is nothing on Mars that is economical interesting AFAIK.

So I think it makes sense to talk also about surface bases, to get more people on board, even if those are potentially quite inefficient.

> build a colony at the bottom of the ocean

Sun enters red giant phase. Oceans boil away. You boil with them, before being engulfed by the sun.

Mars is a stepping stone.

We have a lot less than one billion years. After that, the oceans start to boil.

Other countries have similar scenarios.

At the current rate we don't have to wait for the sun to kill us, climate change will do that first. Sure, it might not be an extinction level event but societal collapse requires much less than that. Disruption of the supply chains needed to maintain a Mars colonization program requires even less than that.

So do sea anemones. What are their chances of inhabiting Mars? ~0%.

You can have billions of years of spare time. If you only concern yourself with Earth and never move beyond it, you'll end up just like anemones

> Mars is a stretch goal.

If Mars is a stretch goal, we're fucked. By time of red giant sun Mars will also be toasted.

> climate change will do that first

It probably won't. Devastate and depopulate anything outside arctic circle? Yes.

Nuclear winter has a good chance but even that's not a certainty..

> societal collapse requires much less than that

I don't care about societies I care about totality of humans. All societies exist while their energy/work production can ballance the expanding complexity, or are knocked out of balance by another society.

Societies aren't immortal.

We were nothing more than sea anemones once too. In a billion years you could have literally any lifeform currently on earth evolve into intelligent beings capable of spaceflight. The timeframe is just so unfathomably long thah it's impossible to predict what could happen.

> In a billion years you could have literally any lifeform currently on earth evolve into intelligent beings capable of spaceflight.

That depends on how likely is human-level intelligence to arise, so far only one species arrived there and no other. Then you add expectations of being able to build a spaceship capable of escaping Earth's gravity well.

Hoping some future intelligence can do job we can do now is ultimate form of procrastination.

What do you think where your Mars rockets come from? Who mines the raw materials? Who refines them? Who builds the tech? Who does the assembly? Who does the research to actually make Mars colonization possible?

"Societal collapse" is another way of saying you will not go to space today (or ever). I'm not talking about a society. I'm talking about our entire global economical and political system. Unchecked climate change will wipe out food production and make vast swathes of land uninhabitable.

For someone who seems to focused on human survival and creating self-sustaining life on Mars, you don't seem to have a very good understanding of supply chains (and in case you're unaware: everything has a supply chain, even modern agriculture can't function without entire industries producing its resources and equipment). You'll have a hard time establishing let alone maintaining that on Mars in the next million years if we can't maintain it on Earth in the next hundred.

If you want to ensure human survival, fix climate change first, then we can worry about Mars colonization.