The “heavenly Bodies” thread got me thinking that we’d have 3 habitable planets in the solar system if Mars had the mass of Venus and vice versa.
I propose that we switch the positions of Venus and Mars around. How we do that is irrelevant, perhaps we can do periodic large asteriod flybys. ( though it would have to be fast enough to allow both planets to slip past earth’s orbit past each other without throwing hte whole solar system in dis-array at the same time)
Venus, moved to the position of Mars, would be able to cool down, and with the addition of cometary ices, be able to acheive a stable climate ( as long as the rotation rate was sped up) and fix all the excess carbon out of the air. It is geologically active enough to keep itself warm at the increased distance. It would settle down to a climate cooler than Earth’s, dependant upon how much water was added to it.
Mars, moved to the position of Venus, would experience much warming, and thickening of its atmosphere, but it probably not geologically active enough to generate enough carbon dioxide to create a run-away greenhouse effect. It would settle down to a climate that is warmer than Earth’s, but probably not too much warmer.
Mars seems to be the more unknown one to me. Without knowing how much CO2 there is locked in the ground, it’s impossible to know how high the greenhouse effect of being closer to the sun would raise the temperature. It wouldn’t get as high as Venus for sure, since geological activity is sparse at best, but it might get pretty darn hot indeed.
Venus seems like it would just settle down into a slightly colder earth, with one hot side, and one frozen side, unless the process that moved the planet also speeds up its rotation.
Any thoughts on what you think would happen to the respective climates?
An interesting idea - I’ve wondered how one might increase the mass of Mars to have more atmosphere, etc. Not that your idea is any more feasable than any I’ve thought of. There’s also the fact that your neighbours probably don’t like you moving your car around at 3am - try sneaking a planet by and they’re gonna throw a hissy fit.
I don’t have anything useful to add except to ponder whether Mars would be able to keep any newly sublimated atmosphere. I recall a formula for what % of which gasses could escape a particular strength of gravity well, but it’s late and I don’t know where my University physics text is.
as I understand it, Mars would keep a respectable atmosphere for millions of years;
however, millions of years is not very long on a geological timescale.
How long a timescale do you want to consider?
Another technique is putting up inflatable domes tens or hundreds of kilometers in extent; eventually you could cover the planet in them.
(the worldhouse concept);
Venus needs a combination of sunshades and mirrors to make it habitable- there is no practical way of moving it or increasing the rotation.
Oh and a lot of work on the atmosphere, of course.
There’s also the fact that your neighbours probably don’t like you moving your car around at 3am - try sneaking a planet by and they’re gonna throw a hissy fit.