Unpiloted and looking rather like a large, fat fighter aeroplane, it is launched from a converted Boeing 747. Having released the upper stage at about one half satellite speed, the rocket-powered lower stage glides back to base and lands.

• X-34无人驾驶，外观更像一个庞大的战斗机，它从一个经过改造的波音747飞机上发射，当以约为卫星的一半速度释放上部一级火箭后，采用火箭发动机驱动的下部一级火箭就滑降回基地并着陆。