May 28, 2008, file photo: Space shuttle Discovery commander Mark Kelly, right, gestures as he walks with his twin brother astronaut Scott Kelly, left, and mission specialist Ron Garan, after arrival at Kennedy Space Center in Cape Canaveral, Fla. Terry Renna/AP hide caption

itoggle caption Terry Renna/AP

A makeshift memorial outside the University Medical Center in Tucson includes candles and this photo of Rep. Gabrielle Giffords with supporters. John Moore/Getty Images hide caption

itoggle caption John Moore/Getty Images

Mark Kelly holding the hand of his wife, Rep. Gabrielle Giffords, in her room at University Medical Center in Tucson on Sunday, Jan. 9, 2010. Office of Rep. Gabrielle Giffords/AP hide caption

itoggle caption Office of Rep. Gabrielle Giffords/AP