Captain Mark Kelly hugs his wife, Rep. Gabrielle Giffords (D-Ariz.) at the White House in October. The White House/Getty Images hide caption

itoggle caption The White House/Getty Images

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