A Coast Guard skiff keeps watch on the waters surrounding space shuttle Atlantis before the shuttle's lift off on the STS-135 mission.

A Coast Guard skiff keeps watch on the waters surrounding space shuttle Atlantis on its seaside launch pad at NASA's Kennedy Space Center in Florida before the shuttle's lift off on the STS-135 mission.

Atlantis and its crew of four; Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim are scheduled to lift off at 11:26 a.m. EDT on July 8 to deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts for the International Space Station. Atlantis also will fly the Robotic Refueling Mission experiment that will investigate the potential for robotically refueling existing satellites in orbit. In addition, Atlantis will return with a failed ammonia pump module to help NASA better understand the failure mechanism and improve pump designs for future systems. STS-135 is the 33rd flight of Atlantis, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program. For more information, visit www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/index.html. Photo credit: Ken Thornsley