English: Evening light begins to fade at NASA's Ames-Dryden Flight Research Facility (later redesignated Dryden Flight Research Center), Edwards, California, as technicians begin the task of mounting the Space Shuttle Atlantis atop NASA's 747 Shuttle Carrier Aircraft (NASA #911) for the ferry flight back to the Kennedy Space Center, Florida, following its STS-44 flight 24 November-1 December 1991. Post-flight servicing of the orbiters, and the mating operation, is carried out at Dryden at the Mate-Demate Device (MDD), the large gantry-like structure that hoists the spacecraft to various levels during post-space flight processing and attachment to the 747.