Credit: © Mark Wade
Status: Study 2005. Thrust: 44.10 kN (9,914 lbf). Gross mass: 20,000 kg (44,000 lb). Unfuelled mass: 10,000 kg (22,000 lb). Specific impulse: 350 s. Height: 20.00 m (65.00 ft). Diameter: 5.00 m (16.40 ft).
It would have allowed the CEV, and an entire lunar base, to be established using existing commercial expendable launch vehicles.
The spacecraft was designed for the primary mission of taking four crew to the moon and back. Spacehab gave the lunar mission priority, giving little consideration to the earth orbit space station support and Mars re-entry vehicle roles. The CEV would be launched into low earth orbit in a single EELV launch. After launch, the forward portion, consisting of the CM re-entry vehicle and SM propulsion module, would separate, transpose, and dock with the SHM habitation module. It would then proceed either on its earth orbit mission, or to dock with a waiting trans-lunar injection stage to go on to the moon. The CEV's propulsion was sized to make the braking burn into low-lunar orbit, and the departure maneuver from lunar orbit back toward earth. For earth orbit missions the propellant load could be drastically reduced, and the habitation module loaded with up to 9 metric tons of payload for delivery to the ISS. These large margins were possible because the CM's mass was minimized by using the SHM to provide crew accommodation during orbital flight.
For lunar missions, a succession of nine launches of two types of launch vehicles would be made to low earth orbit. Commercial expendable launch vehicles, with a payload of 15 metric tons and a maximum payload diameter of 4 m, would be used for most components. Two outsized components - the lunar lander stage and the CEV - would need a larger EELV booster (Delta IV Heavy or Shuttle-derived vehicle) with a 20 metric ton payload capability and a 5 m payload fairing. However the 20 metric ton/5 m requirement seems to have been adopted primarily to meet NASA's criteria. In fact, with small adjustments, the whole enterprise could be launched in 15-metric ton chunks using existing commercial boosters (Atlas V, Delta IV, Ariane V, Zenit-3SL, Proton) and payload fairings. The modular components of the trans-lunar injection stages and lunar lander were as follows:
The return-to-the moon scenario would involve launch of the LEV to low earth orbit by an ELV; launch of the LADS to orbit by an EELV; and launch of three SPM's to orbit by as many ELV's. The three SPM's would be expended putting the stack on trans-lunar injection. The LADS would make the lunar orbit insertion burn, putting the lander in low lunar orbit. Meanwhile a further three SPM's would be launched, followed by the CEV by a man-rated EELV. Three SPM's would be expended in sending this stack on trans-lunar injection. The CEV would brake itself into lunar orbit, then rendezvous and dock with the waiting lander. The crew would enter the lander, and descend to the surface, leaving the CEV unmanned in lunar orbit. The LADS would burn a third time to take the crew in the LEV back to lunar orbit, for a rendezvous and docking with the CEV. The crew would transfer to the CEV, jettison the LEV, then head out of lunar orbit back towards earth using the CEV's engine. Near the earth the CM would separate from the CEV, re-enter the atmosphere, and splashdown in the ocean.
Later a lunar base would be established, using additional modules, delivered to lunar orbit by SPM's and landed on the surface by LADS. These would include:
Crew Size: 4. RCS specific impulse: 290 sec. Spacecraft delta v: 2,300 m/s (7,500 ft/sec). Electric System: 4.00 average kW.