HOUSTON --NASA astronaut Mark Kelly resumed training to command the final flight of space shuttle Endeavour in April. Kelly returned to training Monday at Johnson Space Center for the first time since the wounding of his wife, Arizona Congresswoman Gabrielle Giffords, last month in Tucson. Kelly went on personal leave after the shooting to stay by his wife's side. Giffords continues to recover here in Houston. Kelly, who is commanding the mission, now says he is looking forward to rejoining his crew members and finishing training. Kelly's mission will send him to the International Space Station in April. It has the potential to be the last space shuttle mission ever.