Congresswoman Gabrielle Giffords and her husband, astronaut Mark Kelly, showed Americans how optimism, an adventurous spirit and a call to service can help change the world. As a couple, they became a national example of the healing power to be found in deeply shared love and courage, as Gabrielle began her long battle to recover from traumatic brain injury. On Friday, May 4, 2012, at 7:30 p.m.…