Could Mars or Venus support an artificial atmosphere/biosphere/hydrosphe… for future colonization?
Mars is too small to hold onto an atmosphere and therefore can never be made livable. Whatever atmosphere we recreate will drift off into space. Venus already has a dense atmosphere and it just happens to be pretty much identical to earths primordial atmosphere. Venus is therefore an ideal planet to terraform. The only reason Venus isn´t a living planet today is because it is closer to the sun. It never got cool enough for water to condense. The instant rain began falling on earth the atmospheric CO2 dissolved in it reacting with alkaline oxides also dissolved in it to form carbonates. The same thing would happen on Venus if 88% of the sunlight were blocked off. “A planet sized sunblocker? Impossible.” mutter the pro Mars side who instead propose a planet sized mirror by Mars to heat it up. A completely lost cause as a warm dead Mars is still a dead Mars. Plate tectonics is only a result of volcanism which is essential to life on earth. Volcanism replenishes the atmosphere with gasses
