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The Space Shuttle Enterprise (NASA Orbiter Vehicle Designation: OV-101) was the first Space Shuttle built for NASA. It was constructed without engines or a functional heat shield, and was therefore not capable of space operations; its purpose was to perform test flights in the atmosphere. Originally, Enterprise had been intended to be refitted for orbital flight, which would have made it the second space shuttle to fly after ''Columbia''. However, during the construction of Columbia, details of the final design changed, particularly with regard to the weight of the fuselage and wings. Refitting Enterprise for flight would have involved dismantling the orbiter and returning the sections to subcontractors across the country. As this was an expensive proposition, it was determined to be cheaper to build ''Challenger'' around a body frame ("STA-099") that had been created as a test article. Similarly, Enterprise was considered for refit to replace Challenger after the latter was destroyed, but ''Endeavour'' was built from structural spares instead.
Service
Approach and landing tests On January 31, 1977, it was taken by road to Dryden Flight Research Center at Edwards Air Force Base, to begin operational testing. While at NASA Dryden, Enterprise was used by NASA for a variety of ground and flight tests intended to validate aspects of the shuttle program. The initial nine-month testing period was referred to by the acronym ALT, for "Approach and Landing Test". These tests included a maiden "flight" on February 18, 1977 atop a Boeing 747 Shuttle Carrier Aircraft (SCA) to measure structural loads and ground handling and braking characteristics of the mated system. Ground tests of all orbiter subsystems were carried out to verify functionality prior to atmospheric flight. The mated Enterprise/SCA combination was then subjected to five test flights with Enterprise unmanned and unactivated. The purpose of these test flights was to measure the flight characteristics of the mated combination. These tests were followed with three test flights with Enterprise manned in order to test the shuttle flight control systems. Finally, Enterprise underwent five free flights where the craft separated from the SCA and was landed under astronaut control. These tests verified the flight characteristics of the orbiter design and were carried out under several aerodynamic and weight configurations. See ALT table below for complete list of ALT flight tests. Preparation for STS-1 Following the ALT program, Enterprise was ferried between several NASA facilities to configure the craft for vibration testing. In 1979, it was mated with an external tank and solid rocket boosters and tested in a launch configuration at Kennedy Space Center launch pad 39A. In 1985, it was used to test the Air Force shuttle facilities at Vandenberg Air Force Base, including a full mating on the SLC-6 launch pad. Retirement With the completion of critical testing, Enterprise was partially disassembled to allow certain components to be reused in other shuttles, then underwent an international tour visiting France, Germany, Italy, the United Kingdom, Canada, and the U.S. states of California, Alabama, and Louisiana. It was also used to fit-check the never-used shuttle launch pad, SLC-6 at Vandenberg AFB, California. Finally, on November 18, 1985, Enterprise was ferried to Washington, D.C., where it became property of the Smithsonian Institution. Post-Challenger After the Challenger disaster, NASA had a choice of which shuttle to use as a replacement. Refitting Enterprise with all of the necessary equipment needed for it to be used in space was considered, but instead it was decided to use spares from the fabrication of Discovery and Atlantis to build Endeavour. Post-Columbia In 2003, after the breakup of Columbia during re-entry, the Columbia Accident Investigation Board removed a fiberglass panel from Enterprise's wing to undergo testing *. The test involved firing a piece of foam at high velocity at the panel. While the panel was not broken as a result of the test, the impact was enough to permanently deform a seal. As the Reinforced Carbon-Carbon panel on Columbia was 2.5 times weaker, this strongly suggested that the RCC leading edge would have been shattered. Additional tests on the fiberglass were canceled in order not to risk damaging the test apparatus, and a panel from Discovery was tested to know the effects of the foam on a similarly-aged RCC leading edge. A piece of foam from the external fuel tank broke off and struck the leading edge of Columbia's left wing during launch. The Columbia Accident Investigation Board determined that this impact caused a breach of a Reinforced Carbon-Carbon panel along the leading edge of Columbia's left wing, allowing super-heated gases generated during re-entry to enter the wing and cause structural collapse. This caused Columbia to spin out of control, breaking up with the loss of all crew. Current status Enterprise was at the Smithsonian's hangar at Washington Dulles International Airport before being moved to the newly-built Smithsonian's National Air and Space Museum's Steven F. Udvar-Hazy Center at Dulles, where it is the centerpiece of the space collection. Table of ALT flights Related media See also | |||||||||||||||||||||||||||||||||||||||||
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