When the space shuttle was unable to land back at Kennedy Space Center, it landed instead at NASA Dryden Flight Research Center within Edwards Air Force Base in California. This necessitated a ferry flight back to Florida and the Mate-Demate (MDD) hoisted the shuttle into place for its piggyback ride to get there. Of the 135 shuttle missions, 54 of them ended at Edwards, all of them using the MDD. Built in 1976, the MDD was also utilized for the Approach and Landing Tests performed by the prototype Shuttle Enterprise in 1977.
All post-mission shuttle processing happened outside at the MDD and never inside of the Shuttle Hanger constructed directly adjacent. Hazardous chemicals were removed, the tail cone installed and time sensitive cargo removed from the Crew Module. This process, in addition to the mating with the 747 Shuttle Carrier Aircraft (SCA), took about a week depending on weather.
The Kennedy Space Center MDD was used mostly for demating, but occasionally an orbiter would need to fly back to California for upgrades.
(Photo Credit: NASA)