Access to Fuel Tanks in the LTV Service Module

Although the service module shape carries through the shape of the Spacehab modules, it is not really made up of Spacehab modules. What you're really seeing is the outside of a thin membrane of multilayer insulation (MLI). The MLI is a debris shield, supported on a flimsy wire frame. It just looks robust. We make it sections and hinge each section to form doors, which swing up to allow access to the fuel tanks. This is very similar to the approach to the shielding used on the International Space Station.

This image gives an idea of current thinking on the issue. Once we can get oxygen and tanks from the moon, we can swap out those tanks in lunar orbit. We'll launch hydrogen in fresh tanks from Earth. Like the LTV scenario, we'll ferry the empties to lunar orbit and perhaps even land them on the moon to be refilled.

A central truss runs down the length of the LTV Service Module. The truss provides attachment points for the tanks as well as support for fuel and thermal control system plumbing, RCS rockets and their tanks, external avionics, power and data wiring, and finally the engines with their gimbal mechanisms, controllers, and pumps.