Project Orion: Room Enough for a Football Team
(http://bruce.org.uk/images/orioncrewmod2.jpg)
The ultimate objective for Project Orion is to get back to the moon and then move on to land man on Mars.
The large size crew module permits more personnel to be transported to a moonbase or to dock with an orbiting workshop (like ISS but in moon orbit), where a suitably sized craft for Mars can be assembled.
(http://bruce.org.uk/images/orioncrewmod3.jpg)