STA-099

Construction begins on Space Shuttle Structural Test Article 099 (STA-099), a full-sized structural model of the shuttle built for stress and thermal testing. Four years later, NASA decides to abandon plans to refit the test shuttle Enterprise for space duty at great expense, instead opting to upgrade the STA-099 airframe into a spaceworthy vehicle, which will eventually be named Challenger. While the refit will still be expensive, it takes less time and money than a complete teardown and rebuild of Enterprise’s airframe, which was never intended for flight outside the atmosphere.