Argument: Rescue mission to Mars is not possible
Sam Dinkin. "Colonize the Moon before Mars." The Space Review. September 7, 2004: "First, on a mission to the Moon, Earth rescue is a decent possibility for certain kinds of failures. On a trip to Mars, this would be out of the question. As NASA is finding out with its shuttle return to flight efforts, having a standby rescue ship and a space station to go to makes failure recovery for many failures feasible without too much increased capability from our existing hardware."