While the Space Shuttle may not be the best way to get to Mars
But he probably chose them because, unlike Oriion and Ares, tne Space Shuttles actually exist and have flown in
space since 1981.
Like I also said, the underlying purpose of this plan is to make it happen, if not by NASA then someone or some
group with the financies, resources, and chutzpuh.
And here is this article regarding a one-way manned trip to Mars:
http://www.universetoday.com/2008/03/04/a-one-way-one-person-mission-to-mars/
In olden days, people used to sail away to unknown lands for years, and sometimes they did not come back,
in order to colonize new worlds.