re: 2 spacecrafts
It's true if the lander and the orbiter are flying towards the Moon, together, one could save the other if there's a problem.
But what would have happened to Apollo 13 had the explosion occured after the LM had landed on the Moon?
Are the landers not going to be re-usable and travel together with the CEV every time or are they going to stay in lunar orbit and only travel back and forth from moon orbit to moon surface?
The lander isn't always going to be there to help, if the CEV is in trouble.
Raoul