Pegasus launches from vandenberg Published May 2, 2007 By 050407 VANDENBERG AIR FORCE BASE, Calif. -- An Orbital Sciences Pegasus XL rocket was launched from Vandenberg AFB today at 1:26 p.m. The rocket took off from an L-1011 aircraft and carried NASA's Aeronomy of Ice in the Mesosphere (AIM) spacecraft into orbit. NASA's launch director for the mission was Omar Baez. AIM is a two-year mission to study Polar Mesospheric Clouds. These are the Earth's highest clouds, which form an icy membrane 50 miles above the surface at the edge of space. These clouds, which are visible from the ground with the naked eye, form in the spring and summer at high latitudes and have been seen for over a century, reflecting the Sun's light in the twilight sky. The mission's primary goal for the spacecraft's three instruments is to explain why these clouds form, and discover what is causing them to appear more frequently and at lower latitudes. "Another successful launch for the Air Force to help celebrate our 60th Anniversary," Colonel Terry Djuric, 30th Space Wing vice commander said. "I am proud of the dedication and joint effort from the 30th Space Wing, NASA, Orbital Sciences, and all launch agency partners that made this event a huge success."