Atlantis rolls to Launch Pad 39A. Photo Credit/NASA TV

Shuttle Atlantis began an overnight “roll out” to Launch Pad 39A at NASA’s Kennedy Space Center Tuesday night, just hours before the Endeavour astronauts were scheduled to descend to Earth, concluding their 16-day mission to the International Space Station.
Atlantis, planted atop a crawler-transporter, emerged from the Vehicle Assembly Building at 8:42  p.m., EDT, to begin the 3.5 mile trek to 39A.
Tentatively scheduled to lift off on July 8, Atlantis will embark on a 12-day supply mission to the orbiting science laboratory with four astronauts. The flight will close out NASA’s 30-year shuttle program.
Meanwhile, Endeavour’s 25th and final flight was scheduled to end with a Florida landing on Wednesday at  2:35 a.m., EDT.
Atlantis was expected to reach the coastal launch pad about an hour after  Endeavour’s Florida return.  The roll out was delayed by a temperary mechanical problem with the crawler-transporter.

Favorable weather was forecast for both operations.

Atlantis commander Chris Ferguson, left, and his crew watched as Atlantis rolled to the launch pad. They are, left to right, pilot Doug Hurley and mission specialists Sandy Magnus and Rex Walheim. Photo Credit/NASA TV

Endeavour commander Mark Kelly led a crew of six astronauts. The fliers equipped the space station with the $2 billion Alpha Magnetic Spectrometer and spare parts for the thermal control, communications and robotic systems.
Discovery was retired after a March mission.