My big idea for Venus, assuming infinite power, would be to shoot a series of big asteroids past it and use the gravity/inertia drag to make it spin faster.

Then, when Venus is spinning fast enough, collide the asteroids together to give Venus a moon and tides.

While all that is going on, use some sort of huge electromagnet to spin Venus' internal heavy core to provide a strong magnetic field to deflect nasty stuff from the Sun and elsewhere.

Also build a shield to stop all sunlight reaching Venus, thus freezing the atmosphere onto the surface. That makes reprocessing the crust into something Earth-like much easier.

Comets could then be used to provide oceans.

Shouldn't take more than a few tens of thousands of years! Seems like something a few humans, downloaded into robots, could do.

Mars would remain a scientific research station like Antarctica, assuming that life is found there. I'd treat Europa and anywhere else with life the same way.

I assume, once you have allmost self replicating robots, who can do mining asteroids and building factories to build more of them and mine more and build more .. you would not need ten of thousands of years. Maybe even only some decades.

Maybe this is what Factorio has been preparing me for all this time! https://en.m.wikipedia.org/wiki/Factorio

Just make sure that you have not invented Alastair Reynolds' "greenflies".

I figured tens of thousands of years mostly for the crust reprocessing on Venus itself, for the asteroids to coalesce into a big hot blob, and for the moon blob to cool down.

SimEarth mod downloading

Day length seems less of a concern than the temperature and resources issues (since you can use artificial lighting), plus you can float around in the balloon to choose to be in a light, dark, dusk or dawn place, and even enjoy an eternal sunset. This almost sounds like it would fit Le Petit Prince

The floating cities are surely a way to circumvent the daylength issue. But the daylength is directly linked to the temperature - even if you could normalize the atmosphere, the day side would still get just too hot and the nightside too cold.

I personally would bombard with comets. Bring down the temperature and deposit water on the planet.

Are there so many ice comets avaiable?

Also, would the temperature really go down and not be negated by the kinetic impact?

Apart from that, more water probably helps, if we do not need that water more urgently on mars.

There are billions of comets available https://en.wikipedia.org/wiki/Kuiper_belt

Then there is also https://en.wikipedia.org/wiki/Oort_cloud

Don't worry - there is more than enough comets to bomb the Mars with all the future settlements. Muhaha

Good to know ... otherwise a possible future would involve hunting and waging war for the few ice comets ..

Isn't the common scifi solution to drop some engineered bacteria into the atmosphere to convert the CO2 and generate a think ozone layer?

Not since sci-fi authors figured out that, given human success rates at bioengineering, the likely result is an uninhabitable planet-wide nanotech/bacterial goo that eats anyone who lands.

The ice comet solution has the added benefit of wiping out all of those pesky Martians, given the kinetic energies involved. Just ask any Pak Protector. (-:

Let’s sort that out on Earth first. :p

Why yes, let's test out something that can kill billions on Earth before trying it on an uninhabited area.

I think he meant, before we try to mess with a planet far away, we have a CO2 problem here on earth already urging to be solved in general. Not necessarily, to experiment wildly in the process here on earth.

I would bet the solution for Earth is going to be wildly different than one used on Venus. Earth will require carbon removal that can safety be used with people present. The Venus solutions all sound very, very unfriendly to be present for.

It was a joke, relax.

Stap this nonsense. It is clear that there is overpopulation on this planet, where most of the population want to consume all available resources to them, but there must be easier ways to deal with that problem... CO2 is food for plants. If you take away CO2 out of atmosphere of Earth, it is end of life for oxygen breathing life - Earth is inhabited not only by intelligent morons. Rise of temperature on Earth is not caused by CO2(which is generated also by volcanoes), that is generated by humans, but by behavior of Sun. Winter around poles is caused by inclination of Earth - not because there is abundance of CO2... oh, I must have mixed something up, because when I started to read sci-fi, it was all about next Ice Age on Earth. And that we are doomed and that everyone will die. And we need to get to different planet. Despite that there are no habitable planets in reasonable distance. With no breathable air or water. And if there were, then we would be kicked out, if we tried to land. Because that is not how things works - if you have habitable planet, you should care about it.

There is no H on Venus surface, so it is impossible to change Venus with local resources. So, they have to be imported - and there is H in comets. So, the only way to teraform Venus is with bombarding it with thousands of comets and space junk, that contains ice. Maybe getting H out of gas planets might be another source, too.