In 1952, the US Air Force began Project Blue Book, a study program on UFOs.

1952年，美国空军开始着手实施“蓝皮书计划”，这是一项针对不明飞行物的研究项目。

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This, together with a decline in sighting activity, led to the dismantling of Project Blue Book in 1969.

这份报告随着目击事件的减少，导致了 1969 年 Blue Book 计划的解散。

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A second committee was set up in 1966 at the request of the Air Force to review the most interesting material gathered by Project Blue Book.

在1966年，由于空军想要复查Blue Book计划中搜集的最有意思的材料而成立了第二支委员会。

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