星际旅行一直是人类的梦想之一。太空探索公司SpaceX于2016年4月27日宣布,他们将于2018年向火星发送一艘太空飞船,为人类能到邻近星球上生活和旅行迈出大胆的一步。届时,他们不但要把飞船送上火星,而且要让搭送飞船的火箭再重新飞回地球。大家可能知道,无论是把人造卫星送上既定的轨道,还是运输物资到空间站,或者把飞船送到火星上面,一般都要借助运载火箭,而传统设计的火箭都只能执行一次任务,不能反复使用。它在完成发射任 Star Trek has always been one of human dreams. Space Exploration Corporation SpaceX announced on April 27, 2016 that they will send a spacecraft to Mars in 2018 to take a bold step toward living and traveling on the nearby planet. At the appointed time, they will not only send the spacecraft to Mars, but also let the rockets taken from the spacecraft fly back to earth again. As you may know, whether it is sending satellites to a given orbit, transporting supplies to a space station, or sending a spacecraft to Mars, we usually rely on launch vehicles, whereas traditional design rockets can only perform one mission and can not be repeated use. It finishes firing