Blast From The Past – February 1, 1985 – The Space Shuttle Enterprise in launch position on the Space Launch Complex (SLC) #6, commonly known as “SLICK 6”, during the ready-to-launch checks to verify launch procedures at Vandenburg AFB, California. – Photo by TSgt. James R. Pearson
According to the NASA Website: NASA ferried Enterprise to Vandenberg Air Force Base in California to conduct fit checks at the Space Launch Complex-6 (SLC-6), which NASA had planned to use for polar orbiting shuttle missions. NASA used Enterprise to conduct tests at SLC-6 similar to the 1979 tests at KSC’s Launch Complex 39. The tests at Vandenberg complete, NASA ferried Enterprise back to Dryden on May 24, 1985.
From Wikipedia: Space Shuttle Enterprise (Orbiter Vehicle Designation: OV-101) was the first orbiter of the Space Shuttle system. Rolled out on September 17, 1976, it was built for NASA as part of the Space Shuttle program to perform atmospheric test flights after being launched from a modified Boeing 747. It was constructed without engines or a functional heat shield, and was therefore not capable of spaceflight.
Originally, Enterprise had been intended to be refitted for orbital flight to become the second space-rated orbiter in service. However, during the construction of Space Shuttle Columbia, details of the final design changed, making it simpler and less costly to build Challenger around a body frame that had been built 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]
Enterprise was restored and placed on display in 2003 at the Smithsonian’s new Steven F. Udvar-Hazy Center in Virginia. Following the retirement of the Space Shuttle fleet, Discovery replaced Enterprise at the Udvar-Hazy Center, and Enterprise was transferred to the Intrepid Sea, Air & Space Museum in New York City, where it has been on display since July 2012