根据月球研究和行星际飞行任务的需要，为了提高火箭的推重比，要为运载火箭新安装一个第三子级。
Missions for study of the Moon and interplanetary flight required re-equipping the launch vehicle with a third stage to increase its power-mass characteristics.
根据月球研究和行星际飞行任务的需要，为了提高火箭的推重比，要为运载火箭新安装一个第三子级。
Missions for study of the Moon and interplanetary flight required re-equipping the launch vehicle with a third stage to increase its power-mass characteristics.
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