The Space Shuttle-derived Heavy Lift Vehicle is the merely the latest concept that uses the Shuttle external tank and solid rocket boosters to orbit robotic spacecraft or cargo with a side-mounted cargo carrier. But HLV is the first NASA proposal to also include a crewed vehicle.
Designs for side-mount cargo Shuttle-derived vehicles first appeared in 1979, and "Shuttle-C" version studies were published from 1987. But it was not until 1989, three years after the Space Shuttle Challenger disaster, that the unmanned Shuttle idea gained momentum.
That year NASA proposed Shuttle-C, a concept able to place 45,000kg (99,000lb) into low Earth orbit by 1995 but it was not funded. The 2003 loss of the orbiter Columbia renewed interest in the Shuttle-C idea and in 2004 an industry team started developing its own side-mounted cargo carrier version capable of placing 68,000kg into LEO.
However, NASA's 2005 Exploration Systems Architecture Study report, which underpins its return-to-the-Moon Constellation programme, rejected side-mounted designs owing to inadequate lift capability.
Source: Flight International
