President Barack Obama thanks Airmen who directly supported the Nuclear Security Summit, April 15, 2010, at Joint Base Andrews, Md. Airmen from Joint Base Andrews were joined by deployed personnel from around the nation to provide safe and efficient transition into and out of the United States for a number of foreign leaders in attendance of the Nuclear Security Summit. President Obama left for the Kennedy Space Center in Cape Canaveral, Fla., to announce his new space program. (U.S. Air Force photo by Airman 1st Class Perry Aston) (Released)