The Space Shuttle Enterprise (NASA Orbiter Vehicle Designation: OV-101) was the first Space Shuttle orbiter. It was built for NASA as part of the Space Shuttle program to perform test flights in the atmosphere.  It was constructed without engines or a functional heat shield, and was therefore not capable of spaceflight. On September 17, 1976, the first full scale prototype was completed.

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 to test the shuttle flight control systems.

On August 12, 1977, the space shuttle Enterprise flew on its own for the first time.  Enterprise underwent four more 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.  The first three flights were flown with a tailcone placed at the end of Enterprise's aft fuselage, which reduced drag and turbulence when mated to the SCA. The final two flights saw the tailcone removed and mockup main engines installed. On the fifth and final glider flight, pilot-induced oscillation problems were revealed, which had to be addressed before the first orbital launch occurred.

Following the conclusion of the ALT test flight program, on March 13, 1978, Enterprise was flown once again, but this time half way across the country to NASA's Marshall Space Flight Center (MSFC) in Alabama for the Mated Vertical Ground Vibration Testing (MGVT). The orbiter was lifted up on a sling very similar to the one used at Kennedy Space Center and placed inside the Dynamic Test Stand building, and there mated to the Vertical Mate Ground Vibration Test tank (VMGVT-ET), which in turn was attached to a set of inert Solid Rocket Boosters (SRB) to form a complete shuttle launch stack, and marked the first time in the program's history that all Space Shuttle elements, an Orbiter, an External Tank (ET), and two SRBs, were mated together. During the course of the program, Enterprise and the rest of the launch stack would be exposed to a punishing series of vibration tests simulating as closely as possible those expected during various phases of launch, some tests with and others without the SRBs in place.

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 spaceflight 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 less costly 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.

With the completion of critical testing, Enterprise was returned to Rockwell's plant in Palmdale in October 1979 and was partially disassembled to allow certain components to be reused in other shuttles. After this period, Enterprise was returned to NASA's Dryden Flight Research Facility in September 1981.  During 1983 and 1984, Enterprise underwent an international tour visiting France, Germany, Italy, the UK, Canada, and the American states of California, Alabama, and Louisiana (during the 1984 Louisiana World Exposition). It was also used to fit-check the never-used shuttle launch pad at Vandenberg AFB, California. Finally, on November 18, 1985, Enterprise was ferried to Washington, D.C., where it became property of the Smithsonian Institution.

Enterprise was stored at the Smithsonian's hangar at Washington Dulles International Airport before it was restored and moved to the newly built Smithsonian's National Air and Space Museum's Steven F. Udvar-Hazy Center at Dulles International Airport, where it was the centerpiece of the space collection.  On April 12, 2011, NASA announced that Space Shuttle Discovery, the most traveled orbiter in the fleet, would be added to the collection once the Shuttle fleet was retired. On April 17, 2012, Discovery was transported by Shuttle Carrier Aircraft to Dulles from Kennedy Space Center, where it made several passes over the Washington D.C. metro area.

On December 12, 2011, ownership of the Enterprise was officially transferred to the Intrepid Sea, Air & Space Museum in New York City.  In preparation for the anticipated relocation, engineers evaluated the vehicle in early 2010 and determined that it was safe to fly on the Shuttle Carrier Aircraft once again.  At approximately 9:40 am Eastern Daylight Time on April 27, 2012 Enterprise took off from Dulles International Airport en-route to a fly-by over the Hudson River, New York's JFK International Airport, the Statue of Liberty, the George Washington and Verrazano-Narrows Bridges, and several other landmarks in the city; in an approximately 45-minute "final tour". At 11:23 am Eastern Daylight Time Enterprise touched down at JFK International Airport.

The mobile Mate-Demate Device and cranes were transported from Dulles to the ramp at JFK and the shuttle was removed from the SCA overnight on May 12, 2012, placed on a specially designed flat bed trailer and returned to Hangar 12.  On June 3 a Weeks Marine barge took Enterprise to Jersey City.  It was hoisted June 6 onto the Intrepid Museum in Manhattan.

Source: Wikipedia