@ninja8tyu @djsumdog I am honestly bemused by the obsession with terraforming Mars. One of the major problems with offworld colonization is lack of sufficient gravity. We know that mammals can not properly reproduce without enough gravity, and Mars' gravity is likely not sufficient. The best place outside of Earth that has near-Earth gravity and would be the best for long term human colonization is *Venus*, specifically high up in the atmosphere where the temperature and pressure are almost identical to Earth. Aside from the effective rotation time (day/night cycle), it's almost exactly the same except for atmospheric composition. However, our atmosphere of nitrogen/oxygen is a lifting gas and would be at equilibrium. You could have floating cloud cities if you got an outershell resistant to the sulfuric acid clouds. The best part of this is that these floating cities are already technologically feasible.