So how can we Terraform Mars to make it like Earth then? It seems impossible due to the gravity being so small. Even if we melt ice caps and get liquid water running again, it will slowly evaporate to space? How could a colony on Mars then be self sustaining with this problem?
As the other reply mentioned, this is a millions of years sort of problem. But there are two straightforward solutions. First, in the new atmosphere make sure there's enough oxygen to breath so that an ozone layer forms. That's something we want to do anyways. Also, give Mars a magnetic field. That's a stupendously large but straightforward engineering problem, sort of like terraforming is in the first place but smaller.
