119006main External Tank Cutaway 5530x2060

The External Tank - 154 feet in length with a diameter of 27.5 feet—is the largest single piece of the Space Shuttle. During launch the External Tank also acts as a backbone for the Orbiter and Solid Rocket Boosters to which it is attached. In separate pressurized tank sections inside, the External Tank holds the liquid hydrogen fuel and liquid oxygen oxidizer for the Shuttle’s three Main Engines. During launch the External Tank feeds the fuel under pressure through 17-inch-wide lines which then branch off into smaller lines that feed directly into the Main Engines. Some 64,000 gallons of fuel are consumed by the Main Engines each minute. Machined from aluminum alloys, the Space Shuttle’s External Tank is the only part of the launch vehicle that is not reused. After its 526,000 gallons of propellants are consumed during the first eight and one-half minutes of flight, it is jettisoned from the Orbiter and breaks up in the upper atmosphere, its pieces falling into remote ocean waters.