External Tank ET-94
Lockheed Martin at NASA Michoud Assembly Facility · About 2001
Not currently on display. The Samuel Oschin Air and Space Center opens to the public on 13 November 2026; before that date the object is not viewable. Confirm gallery placement on the museum website after opening.
The great orange cylinder at the heart of the shuttle stack is the external tank, and it is the part of the system that never came home. On every mission the tank fed liquid hydrogen and liquid oxygen to the orbiter's three main engines for the eight and a half minutes of powered flight, then separated and broke up over the ocean. Every tank that flew was destroyed, so the only ones left are those that never launched. ET-94 is one of them, and it is the last tank of the type that was cleared to fly, which makes it irreplaceable.
Look at its surface. The orange colour is not paint but the natural colour of the foam insulation, sprayed on to keep the propellants at hundreds of degrees below zero from boiling off in the Florida sun. The first two tanks were painted white; NASA stopped painting them in 1981 to save about six hundred pounds of weight. The tank is really two tanks, a small oxygen tank in the nose and a large hydrogen tank below, joined by a ring called the intertank where the boosters attach. Notice the feed lines running down the side toward the orbiter and the bolts, more than a metre long, that hold the whole assembly together.
ET-94 was built in New Orleans and kept there after the Columbia accident in 2003, when its foam was studied to understand what had gone wrong. NASA gave it to the Science Center in 2015, and in 2016 it travelled by barge through the Panama Canal and up the Pacific coast, then through the streets of Los Angeles on a sixteen mile overnight journey watched by thousands. Standing beside it in the new gallery, you realise how small the orbiter is by comparison; the shuttle everyone pictures is really a glider strapped to a fuel tank.
Did You Know? ET-94 arrived in Los Angeles by sea through the Panama Canal, a voyage of more than six weeks, because no aircraft could carry it.
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