NASA has selected for further study a 70t (154,000lb) -to-geostationary orbit (GEO) cargo carrying Space Shuttle-derived launch vehicle (SDLV) and a modified solid rocket booster (SRB) for crew launches, for its Exploration Transportation System (ETS).

The two vehicles were selected from seven SDLV configurations offered by the industry at a technical meeting earlier this month. Six of the configurations have GEO capabilities of 50-70t and one has 100t. The SDLVs are in competition with evolved expendable launch vehicle (EELV) derivatives for the role of cargo carrier and crew launcher for the US space exploration vision.

Despite the decision to study an ETS with a solid rocket booster (SRB) -based crew launcher and SRB/external tank combination cargo launcher, NASA is split internally over SDLV. " The vehicles all require substantial modifications to the [launch pad] infrastructure, which really raises their cost and means you cannot even start thinking about flying them until Shuttle goes away [in 2010, and] current thinking is more expensive than the programme can afford," says a NASA source.

Use of an SDLV will preclude flight tests until at least 2012 because it will take two to three years to make the Shuttle pad modifications, but the first manned Moon mission is scheduled for 2015.

The SDLV Moon mission scenario envisages three launches. Two 70t vehicles could carry the Earth Departure Stage (EDS), previously known as trans-lunar injection stage, and the crew habitat. They would be linked once in orbit.

The third launch would be the modified SRB that carries the crew exploration vehicle to the EDS/habitat vessel.

Source: Flight International