History
January 5, 1972 - President Nixon approved the three-element Space Shuttle consisting of an Orbiter, SRBs, and a disposable propellant tank
1975 - Martin Marietta Aerospace became the prime contractor
1976 - The first ET was assembled at the Michoud Assembly Facility in New Orleans, Louisiana
July 1977 - Fabrications for the first flight ET began
December 1977 - First ET tanking test was conducted
July 1979 - The first flight ET (External Tank-1) was delivered to Kennedy Space Center
April 12, 1981 - First test flight