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Comment by btkramer9 | Hacker News Reader

I've always wondered if Venus was as habitable as Mars on the surface which we'd choose. The lower gravity well of Mars makes it much easier to come back from which is practically a requirement to go there. But like you said, the jury is still out on how well we can live in lower gravity.

Getting back from Venus after just beginning to colonize it may not be possible with current technology.

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I would choose Venus. The depth of the gravity well is less important when the colonists are being lowered into it from above rather than thrown out from the bottom. If you need something in orbit, you don't drop it down to the planet in the first place.

But as things are, the relative effort to terraform Venus, compared with Mars, is absolutely colossal. It essentially requires a full-blown robotic asteroid mining industry, wherein olivine asteroids are diverted directly to Venus, and magnesium and calcium are mined, sent to Jupiter to produce saturated hydrides, and those sent on to Venus. It will take 1000 years, minimum.

Mars can get realistic results within 200 years, just by diverting water-ice comets and managing temperature.

Getting back from Venus is as easy as launching from Earth: i.e., completely doable with present-day technology. The only issue is getting it there to begin with, but that's not really hard, though we'd probably need to launch several rockets here on Earth, and assemble stuff in space, to get all the mass needed for a single launch on Venus. Landing stuff on this hypothetical Venus would be much easier than on Mars, since this Venus has an atmosphere, and Mars only has an "atmosphere" (one that's 1/200 the pressure of Earth's, not really much of one), so we'd be able to use aerobraking, parachutes, etc. In fact, landing stuff on today's Venus is pretty easy, and the Soviets were doing this ages ago; the only problem is that landers didn't last long because of the heat and corrosive atmosphere.

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