A classified U.S. National Reconnaissance Office KH-11 "Keyhole" satellite was successfully launched into low Earth orbit from Vandenberg AFB, Calif., on Aug. 28 by a United Launch Alliance Delta IV Heavy. The vehicle, which represents only the second Delta IV Heavy flight from the California site, was configured with standard RS-68-powered, liquid hydrogen-fueled common booster cores (CBCs). The launch used an ignition sequence recently developed by ULA and engine maker Aerojet Rocketdyne to counter the formation of hydrogen fireballs that, in previous launches, have enveloped large parts of the first stage of the rocket during liftoff.
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机译：美国机密侦察队KH-11“匙孔”卫星已于8月28日由美国联合发射联盟Delta IV Heavy成功地从加利福尼亚范登堡空军基地发射到近地轨道。该车辆仅代表加州地区的第二次Delta IV重型飞行，其配置了标准的RS-68动力，液态氢燃料通用助推器芯（CBC）。这次发射使用了ULA和发动机制造商Aerojet Rocketdyne最近开发的点火顺序，以抵消氢火球的形成。在先前的发射中，氢火球在升空期间已经覆盖了火箭第一阶段的大部分。
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