long story short mars does not have enough co2 to bring the atmospheric pressure above the Armstrong limit. redirecting the amount of comets require to mars to bring it to that level is also retarded. Instead lets just meet mars halfway genetically engineering colonists to cope with the maximum realistic pressure after nuking the poles 0.012 atm average presssure and 0.024 atm at hellas planitia ITT lets discuss the changes to a human required to meet mars halfway