[ncmncm]

The South Pole starts out way more terraformed than Mars can ever be. It has air, water, gravity, and is warmer. You can just put up domes and it's already way better than Mars. Mineral wealth is only a mile down, under the ice.

Under the sea starts out way more terraformed than Mars can ever be. It has water, gravity, and is warmer. Mineral wealth is right at hand.

The cloud tops of Venus start out way more terraformed than Mars can ever be. It has air pressure, gravity, water, carbon, sulfur, and shirtsleeve temperature.

What motivation does Mars provide that those don't?

[ben_w]

If your goal is to be a multi-planet civilisation, neither Antarctica nor the oceans of Earth would work; also the layer of Venusian atmosphere that you’re describing is way too cold for there to be useful quantities of metals you could extract from the rain (unlike the lower layers, where mountain tops are frosted with metal: https://www.popularmechanics.com/space/deep-space/a11506/hea...).

The other option is the Moon, which has even less atmosphere and even bigger temperature swings than Mars.

[ncmncm]

Planets are for extreme primitives, anyway.

But the point was, if you haven't even proven you can settle a mildly challenging environment, your odds on an actually difficult one don't look good.

[ben_w]

We know by demonstrations that we can make settlements in Antarctica and underwater, we just don’t have any reason to do more than science and military.

Venus, you could only settle by bringing in everything from outside unless and until you can convert the atmosphere in a large way into building materials — Mars at least you only need to convert it into fuel, because you can do at least some of your construction from rocks.

[ncmncm]

All the settlements on Antarctica are utterly dependent on enormous support frequently airlifted from outside. There have been no settlements underwater at all; little more than camping trips have been essayed.

On Venus, plastics, carbon fiber, water, buoyancy gas, and breathing air (I repeat myself) can be made directly from the air and clouds. Plastic and carbon fiber gives you building materials. Robots can gather minerals from the surface and deliver them by balloon to the cloud tops. Insolation provides abundant power, moreso than here; or, a lightweight, unshielded nuke plant may be suspended a mile or more below industrial plant, supported on its own balloon.

Mars will be much more unpleasant than Antarctica. We don't even know whether people can live for long in Mars gravity. We know that long weightlessness is quite harmful.

[ben_w]

If you’re going to use that standard against nuclear submarines and deep-sea oil drilling, it is unreasonable to also say we can make those things from Venusian air. Yes, in a lab, sure — that’s proof of concept, far less than a camping trip, and roughly the same level as extraction of oxygen from rocks.