CAPE CANAVERAL, Fla. -- Bob Cabana, director of NASA's Kennedy Space Center in Florida, shakes the hand of Mercury astronaut John Glenn as NASA Administrator Charles Bolden applauds at the "50 Years of Americans in Orbit" presentation for Kennedy employees. Mercury astronaut Scott Carpenter joined Glenn, Bolden and Cabana for the event. This year marks 50 years since Glenn and Carpenter became the first two Americans to orbit Earth. Photo credit: NASA/Kim Shiflett KSC-2012-1398