Lunar Transfer Vehicle
The Lunar Transfer Vehicle is a small spaceborne habitat with propulsion systems and support for the crew during flight between Earth and the moon. The current design concept for the Lunar Transfer Vehicle uses the SPACEHAB module as its crew compartment.See section 4.2.1 for more about the Lunar Transfer Vehicle.
For information about the SPACEHAB laboratory, the world's first (and only) commercially developed manned spacecraft, visit http://www.spacehab.com.
Descent Stage + Lunar Base Core Module
This is our initial lunar exploration base. A propulsion package attached to the core module's pressurized habitat lands it on the surface of the moon. The exploration base manned element is based on using three SPACEHAB modules connected in tandem.
See section 4.2.3 for more details about the Lunar Base Core Module.
Ascent Stage
When the crew have compelted their intial exploration of the landing site, they don their space suits and board a simple, open vehicle for the flight from the lunar surface to the orbiting lunar transfer vehicle.
The crew returns to Earth orbit in the Lunar Transfer Vehicle.