The Defense Advanced Research Projects Agency, working alongside Boeing and Aerojet Rocketdyne, has demonstrated that it can successfully fire the AR-22 booster rocket engine 10 times over 240 hours. The test outcome marked a major step in the development of DARPA’s Phantom Express experimental spaceplane, officials said July 10. “We needed to show that main propulsion system, the AR-22, … could in fact support rapid turn operations,” said Scott Wierzbanowski, DARPA’s program manager for the spaceplane. “We were extremely successful. We completely destroyed previously held records of how … you deal with a liquid-hydrogen, liquid-oxygen-type engine.” The agency also proved...