High Quality Content by WIKIPEDIA articles! A Space Shuttle External Tank (ET) was the component of the Space Shuttle launch vehicle that contained the liquid hydrogen fuel and liquid oxygen oxidizer. During lift-off and ascent it supplied the fuel and oxidizer under pressure to the three Space Shuttle Main Engines (SSME) in the orbiter. The ET was jettisoned just over 10 seconds after MECO (Main Engine Cut Off), where the SSMEs were shut down, and re-entered the Earth`s atmosphere. Unlike the Solid Rocket Boosters, external tanks were not re-used. They broke up before impact in the Indian Ocean (or Pacific Ocean in the case of direct-insertion launch trajectories), away from known shipping lanes. The tanks were not recovered.