Mars is definitely the easiest place to colonize, by far. It's much closer than the gas giants, there's no craft capable of taking people to Saturn even devised, let alone constructed. Meanwhile, we have SpaceX actively building a rocket for Martian colonization.

Second, the Venusian atmosphere is oppressive as hell, you'll not be solving that problem anytime soon, as we can't even solve Earth's much easier atmospheric GHG problem.

Martian colonization will be tough. 30% gravity, 3% atmospheric pressure, radiation, very cold, very dry... however, building a base is conceivable and we think we know how to do it.

> SpaceX actively building a rocket for Martian colonization.

It's unknown whether it is capable of protecting the human cargo on its way to Mars. Maybe a design with habitation encased in the propellant tanks is a better idea for longer transits.

In any case, Starship is well positioned for Earth and Moon travels, as well as for sending equipment to LEO and the Moon.

Worst case radiation they'll receive is comparable to if they've been smoking cigarettes the whole trip. That's pretty damn good if you ask me

This is just silly. Of course it’s known if we can transport humans to mars. The answer is yes. The only question is how much it will cost. All you have to do is surround the craft with mass. It doesn’t even have to be attached to the craft. The cost of giving the mass enough energy to get out of orbit and over to mars is the only question.

Is it? https://en.wikipedia.org/wiki/Martian_soil#Toxicity

True Venus' atmosphere is quite hostile, but from what I briefly read Venus quite probably have had a similar atmosphere with Earth (along with Mars) in the early days, before the runaway green-house effect got the best of it, so at least in theory it should be possible to transform it back.

With autonomous robots perhaps it could be done in a span of million years. Maybe. A relatable analogue might be removing liquid from a glass with a tiny straw. Yet I'd think it is easier to remove, than to add material when speaking about terraforming.

I've often wondered if crashing a metropolis-sized piece of ice into Venus might help? Deflected from Saturn's rings or some such. The water vapor could cool it/reflect sunlight.

I doubt increasing albedo would help much. Venus already has the highest albedo of any planet in our solar system (at 0.75, versus, for perspective, our moon's 0.12), due to its effectively-100% sulfuric acid cloud cover:

https://sciencing.com/albedo-planets-5203.html

https://www.universetoday.com/36833/albedo-of-venus/

Also, I doubt an insignificant chunk of ice (relatively speaking) could help cool it, or increase albedo.

I think the first order of business on Venus, if one wanted to colonize the surface (rather than colonize the atmosphere, which I think is doable), would be to "harvest" the gases of the atmosphere and thin it out to something more resembling Earth's.

It's not a question of cooling it. It went into a runwaway greenhouse effect (https://en.wikipedia.org/wiki/Runaway_greenhouse_effect) and it lacks hydrogen. All the hypothetical oceans oxygen bonded with carbon and hydrogen/water vapor was blown off by solar wind. The underlying cause was the loss of the protective magnetosphere.

Also, you are probably looking more to continent or small moon size quantities of ice (if that even works, and if the magnetosphere issue was somehow addressed) that metropolis.

Have you considered how much kinetic energy it would have, coming all of the way down the well from Saturn?

Enough to ionize the water molecules into H and O? Which returns hydrogen to the atmosphere, which is the missing component causing the runaway greenhouse effect?

> And you'd mostly spend your life in bunkers underground

That's okay for many people knowing they are in the forefront of humanity's interplanetary expansion. Also, probably whatever they do will enter the history books as epic heroic acts.

Well yes. Here on earth there are indeed many people who think they want that. Mars one proved at least that.

But I am not so sure, if they will be also so happy on mars, if they really have to be underground allmost the whole time and teleoperate the robotic exploration and mining on the surface etc.

For me the dark winter already is every year challenging. But being in a dark winter so to say forever, would not be bearable for me.

Not having good lighting is indeed a dealbreaker, but there's no real reason why we can't make artificial lights that look close enough to the sun.

Similarly if some caves are street sized, being there would not feel like being underground. Add to that better vr, and ability to jump really high due to low gravity and living in martian cave will be almost better than living in many cities here on earth (of course this is assuming 0.3g is high enough to prevent adverse effects astronauts see in 0g).

Sure. I also see no reason why we could not engineer domes that shield us from the radiation. Or at least shield good enough to allow for some hours every day "outside".

But the first pioneers will be probably cave dwellers or will die of cancer after a few years. Which is probably exepteble for quite some people, if they get those pioneer years instead...

The artificial sun is a solved problem. There are even commercially available products for that: https://www.coelux.com/

The problem with the winter that you stuck in your "small" house. If you create Cosco sized "open" space underground it won't be a problem for most of the people.

Those electric suns really did not convince me at all. I do not know if your linked product uses a new technology, but the ones I tried, I disliked and they could never replace the real sunlight for me.

And yes, I also meant the space problem. Open space underground might solve it for some people, but probably not for me. I would always feel like in a prison, if I cannot go outside and feel real wind. But humans are adoptable. Still, I suspect quite many, who think they want that, would probably go crazy, if they really would be stuck in a bunker forever.