The X-51A Waverider flew its fourth and final mission May 1 over the Point Mugu Naval Air Warfare Center Sea Range May 1, 2013,during which the test team achieved a record-setting 210 seconds of air-breathing hypersonic flight. Flight testers from Edwards Air Force Base, Cali., played a vital role in the program's success. (U.S. Air Force photo/Bobbi Zapka)