"If Yuri Gagarin had not made this flight I would not have flown to the moon," said US astronaut Thomas Stafford, commander on the first US lunar landing in 1969.

1969年美国登月计划指挥官、美国宇航员托马斯 斯塔福德说：“如果尤里 加加林没有进行首次太空飞行，我可能也没有飞去过月球。”

youdao

In this paper, obtained the translunar trajectory for direct striking the moon, which satisfied some constraints including translunar flight time, lunar landing date.

在给定飞行时间、着月时间、着月入射角及停泊轨道等约束条件下，建立飞月轨道数学模型；

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Everything worked as planned. Everyone expected the third moon-landing flight, Apollo Thirteen, would go as well as the first two.

VOA: special.2009.07.22

They were more than two-thirds of the way to the moon on a flight path that would take them to a moon landing.

VOA: special.2009.07.22