Terraforming Venus

[GrandMasterTerwynn]

Speaking of Mercury, I seem to recall an Asimov space colony that was situated on a planet much like our closest planet to Sol. Since the diurnal half of this planet (like Mercury) experiences blistering heat and the nocturnal half freezing cold, the colony placed in the twilight area between these two extremes. Is this feasible?

Mercury isn't tidally locked with the Sun. Any given point on the planet's surface will still experience day/night cycles . . . albeit slow ones. Fortunately, since Mercury has a vanishingly small degree of axial tilt, the floors of some sufficiently high-walled polar craters will be permanently shaded. So you could establish colonies there, though your ability to work on the surface might be somewhat limited, compared to lower latitudes. Mercury has a significant magnetic field (strong enough to deflect solar wind away from the planet,) and as such, the poles are subjected to constant bombardment from high-energy particles.

[Lord of the Abyss]

The biggest problem with Venus is its atmosphere. If you can get rid of all the CO2 you won't need extremely huge shades.

Actually, you will. Venus is too close to the Sun; even if you magically terraformed it into a perfect copy of Earth, it would immediately go into a runaway greenhouse climate. You need to either move the planet or dim the sunlight.

[AMX]

The planet already has a high albedo.

And increasing it even further will lower equilibrium temperature, just as reducing the amount of light will.

And you want to cool it down in a hurry. Quickest, most easily controllable, way to do that would be to drop the insolation to zero...

Or increase the albedo to near 100%

...and let the heat radiate away (though you want to scrub off the atmosphere at the same time, since you only want something like a tenth of the planet's atmosphere.)

Since the atmosphere is responsible for much of the heat retention, getting rid of it (or most of it) is kinda necessary for a quick cooldown.
But I'd prefer to metabolise the atmosphere into a solid, rather than "blow it into space".
No really elaborate reason for it, just a feeling.

Bunkers would be necessary to begin with, sure, but if the aim is maximizing habitable surface area, you're going to eventually going to want a cheap way of shielding the planet from the solar wind and other particles a planetary magnetic field normally deflects.

Point... if that's the aim.
I'm more thinking of "useable" than "habitable", admittedly.
(Heck, if we want maximum habitable surface, why don't we "just" turn Venus into a Globus Cassus?)

This says nothing about dealing with the planet's geology.

IIRC, that's caused by the high surface temperatures - since we've got to drop these anyway, it's a nonissue.
But I may be misremembering that.

If you could dump that much energy into a system in a controllable manner, it's equally arguable that you're probably also capable of building starships and looking for easier marks than Venus.

Point.

Why? It's uncomfortably close to the Sun, and all your consumables will have to be imported, given that Mercury lacks volatiles. Sure it's got a higher concentration of metals than Earth does, but nickel-iron asteroids are cheaper to get to and exploit than Mercury is . . . so you'd have to have been exploiting the solar system for quite a while before you get to the point where a Mercury colony starts to make sense.

No real reason - it simply sounds neat.

[Ariphaos]

Mercury isn't tidally locked with the Sun.

Err, slight correction, it is, it's just a 3:2 resonance.

Anyway, regarding Venus again, you'd want the Parasol to be at Venus' L1 Lagrance point, which is still rather close to Venus itself, so it will only need to be slightly larger than Venus proper.

The main problem is the L1 point is not stable, and requires frequent (every few weeks) correction.

[Dooey Jo]

The biggest problem with Venus is its atmosphere. If you can get rid of all the CO2 you won't need extremely huge shades.

Actually, you will. Venus is too close to the Sun; even if you magically terraformed it into a perfect copy of Earth, it would immediately go into a runaway greenhouse climate. You need to either move the planet or dim the sunlight.

That's why you don't want to make it into a perfect copy of Earth. Preferably you would turn it into something like Tatooine without any large bodies of water, since water vapour is what probably caused the greenhouse effect to run away in the first place. You could also put a layer of soot or something in the upper atmosphere, which would cool down the surface even more.

[Ariphaos]

Dur, for some reason I thought Terwynn said resonant.

I need more sleep.