Former Sen. John Glenn (left) and Scott Carpenter, the last surviving Mercury astronauts, speak at the Kennedy Space Center on Friday, Feb. 17, 2012, in Cape Canaveral, Fla., during an event marking the 50th anniversary of Mr. Glenn's launch into orbit. (AP Photo/Michael Brown)

Photo by: Michael Brown

Former Sen. John Glenn (left) and Scott Carpenter, the last surviving Mercury astronauts, speak at the Kennedy Space Center on Friday, Feb. 17, 2012, in Cape Canaveral, Fla., during an event marking the 50th anniversary of Mr. Glenn's launch into orbit. (AP Photo/Michael Brown)