The first two extra flights were deep-space missions, with Centaur boosting the spacecraft into an elliptical orbit with an apogee of some 80,000 kilometers to study navigation and reentry problems.

• 最先增加的两次飞行属于深层太空任务，利用森托尔将飞船送人远地点为大约8万千米的椭圆型轨道以研究导航和重返大气层等问题。