In article ,
Bob Martin wrote:
First launch sends up an (unmanned) landing vehicle...
Second launch (would it be possible to launch 2 missions about a day apart?
Or within hours?) sends up the command module...

How tightly you can schedule launches depends more on ground facilities
than anything else. With separate pads (it wouldn't be hard to add a
second Delta IV or Atlas V pad at the Cape), and some investment in the
various support facilities, it's not difficult.

CM rendezvous and docks with the lander in lunar orbit.

As others have pointed out, this leaves you without a lifeboat for trouble
along the way. Moreover, it's unnecessary: if both vehicles boost into
LEO and then go to lunar orbit on similar trajectories, they can instead
rendezvous in LEO and go to lunar orbit together. There is no advantage
to delaying the rendezvous.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |