depends - with water and sunlight we should be able to colonize several planets in our solar system - getting sustainable crops going might be a problem, but once the soil biome is established: profit!
I vaguely remember an article in OMNI about a moss you could launch at Mars to kickstart terraforming.
It was probably all heavily fictionalized, but I keep wondering what happens if some sort of mischievous version of Elon Musk really wanted to just start firing green stuff at that planet to see if any of it would stick.
Nice sci-fi idea, but the surface conditions on Mars are so hostile that the poor defenseless moss would roll over and die.
* Temperatures nearly always below the freezing point of water, often several hundred degrees lower.
* Very small amount of air pressure, 0.6% that of earth, and no oxygen at all.
* Because of the two factors above, no liquid water at the surface.
* High levels of radiation directly from space (primarily the solar wind) to the surface, for lack of a global magnetic field. Astronauts visiting Mars will also need to protect themselves from this threat.
It was probably all heavily fictionalized, but I keep wondering what happens if some sort of mischievous version of Elon Musk really wanted to just start firing green stuff at that planet to see if any of it would stick.