Thomas Lee Elifritz wrote:
September 21, 2004

Put a capsule on the Delta IV Medium, and lunar circumnavigation is
possible, using the upper stage as your service module. In LEO, you
could retrofit the upper stage into space station modules. You get
three Delta IV Mediums for the price of a single heavy.


Only if your service module, and all of the life support and
guidance propulsion requirements, have a mass that is less
than 4 metric tons for Delta IV-M or no more than about
6 metric tons for Delta IV-M+(5,4).

The Apollo Command Module mass was about 6 metric tons, but
its 24.5 metric ton Service Module carried 1.2 metric tons
of equipment and fuel to produce electricity, water, and
oxygen. It also carried a ton or more of RCS fuel and
hardware needed to keep the vehicle under control. The
latter masses would have to be added to the Delta IV second
stage, which would directly reduce payload capability.

- Ed Kyle