the second copy of the Air Force’s X-37B robotic space plane landed at Vandenberg Air Force Base in California early Saturday morning, ending a record-breaking 469-day orbital mission that began atop an Atlas rocket launched from Cape Canaveral, Florida, on March 5, 2011. The safe landing of Orbital Test Vehicle 2 after more than 15 months in space is an indisputable triumph for the U.S. military and space industry. Much less certain is the X-37′s future. Budget cuts, labor woes and the looming specter of a Chinese rival could blunt the diminutive robo-shuttle’s orbital edge.