"The ET is the \"backbone\" of the shuttle during launch, providing structural support for attachment with the Space Shuttle Solid Rocket Boosters (SRBs) and orbiter. The tank is connected to each SRB at one forward attachment point (using a crossbeam through the intertank) and one aft bracket, and it is connected to the orbiter at one forward attachment bipod and two aft bipods. In the aft attachment area, there are also umbilicals that carry fluids, gases, electrical signals and electrical power between the tank and the orbiter. Electrical signals and controls between the orbiter and the two solid rocket boosters also are routed through those umbilicals."@en . . . . "Space Shuttle external tank"@en . . . "The ET is the \"backbone\" of the shuttle during launch, providing structural support for attachment with the Space Shuttle Solid Rocket Boosters (SRBs) and orbiter. The tank is connected to each SRB at one forward attachment point (using a crossbeam through the intertank) and one aft bracket, and it is connected to the orbiter at one forward attachment bipod and two aft bipods. In the aft attachment area, there are also umbilicals that carry fluids, gases, electrical signals and electrical power between the tank and the orbiter. Electrical signals and controls between the orbiter and the two solid rocket boosters also are routed through those umbilicals. Although the external tanks were always discarded, it could have been possible to re-use them in orbit. Plans for re-use ranged from incorporation into a space station as extra living or research space, as rocket fuel tanks for interplanetary missions (e.g. Mars), to raw materials for orbiting factories. Another concept was to use the ET as a cargo carrier for bulky payloads. One proposal was for the primary mirror of a 7-meter aperture telescope to be carried with the tank. Another concept was the Aft Cargo Carrier (ACC)."@en . . . . . . .