Rep. Gabrielle Giffords will undergo skull surgery Wednesday, a source said Tuesday. While the surgery details have not officially been released, the source said Giffords will have part of her skull replaced. It was removed after she was shot in January to reduce the brain swelling. Since then, she has worn a helmet while undergoing intensive rehab in Houston to learn how to walk and talk. Giffords returned to rehab Monday night after traveling to Florida to watch her husband, astronaut Mark Kelly, at the space launch of NASA’s final Endeavour mission.