美航宇局正在研究在航天飞机的助推级上捆绑上两枚固体火箭,以便向大倾角轨道(如极地轨道)发射重载荷,从而满足美空军向极地轨道发射大型军事侦察卫星的要求。同时,利用这种方法还能把别的重载荷发射到其它倾角的轨道上去,所以商业卫星也同样可以使用。现有的航天飞机发射到98度倾角轨道的载荷重量还不足10900公斤,而美空军则要求达到14,500公斤以上。 NASA is studying the bundling of two solid rockets on the spacecraft’s boosting stage to launch heavy payloads on large-angle orbits (such as polar orbits) to meet the requirements of the U.S. Air Force to launch large military reconnaissance satellites to polar orbits. In the meantime, using this method it is also possible to launch other heavy loads onto other orbits of the same inclination, so commercial satellites are also available. The existing space shuttle landed on a 98 degree inclination orbit weighing less than 10,900 kilograms while the U.S. Air Force required more than 14,500 kilos.