Jon Goff has run the numbers
and showed that a two-man moon mission is both feasible and realistic. Out-of-the-box thinking will certainly help us get to the moon (as it did when maverick engineers proposed Lunar Orbit Rendezvous instead of Direct Landing or Earth Orbit Rendezvous for Apollo.) An EELV-based approach was being considered during the O'Keefe days, and might have been able to see the light of day had Sean O'Keefe and Admiral Steidle not packed their bags and skipped town. But Michael Griffin and his band of Zubrinistas are opposed to anything that runs counter to The Case for Mars
. Project Constellation is now consigned to the Stick rocket, mammoth heavy-lift rockets that only exist on paper, and... congressional cancellation?
Jon is right to challenge the assumption that we need to put four men on the moon for seven days (a requirement which essentially sizes the entire architecture.) This is twice the size of Apollo's Lunar Module crew, and they stay for about three times as long as Apollo did. If the Orion capsule can operate unmanned in lunar orbit as NASA wants, a two-man moon mission could achieve all of Apollo's objectives. It should be noted, though, that Project Constellation should surpass the achievements of Apollo rather than merely recapture the glory of days past. Still, crew size and duration of the surface mission should be opened to impassioned debate rather than an arbitrary, politically-imposed solution.
NASA originally specified a crew of three for Apollo with a logical reason in mind: a crew of three allows the crew to operate for 24 hours a day, with one crew member taking an 8-hour rest at all times of day. I believe that the Orion Lunar Module should be sized for a similar contingient, based on a similar logic. I also agree that longer surface stays (seven days for initial Orion missions) are perfectly justified.
In a lunar-surface rendezvous architecture (as Jon proposes,) a total crew of three astronauts will be able to achieve the type of mission I have laid out. For a lunar-orbit rendezvous profile (as NASA has baselined,) a fourth crewmember is only justified if he/she stays aboard the Orion command module. Frankly, if I were an astronaut on the moon, I'd like to know that my buddy was up there in the command module, if for no other reason than to back up the automated control systems which will handle rendezvous after we left the lunar surface.
After thinking about it, Jon's proposal sounds a lot like Early Lunar Access
from General Dynamics back in 1992. ELA was a brilliant plan, but it came in the dying days of the Space Exploration Initiative. Nevertheless, ELA stood in stark contrast to the "First Lunar Outpost
" plan, which returned to the Direct Landing mission mode and made use of an enhanced Saturn V known as "Comet