When the appointed time came to blast Yuri Gagarin into orbit, he simply pushed a button that completed the ignition circuit and watched the motors start.

当推送尤里·加加林进入轨道的预定时刻来临之际，他只是简单地按下一个按钮闭合点火电路并看着发动机启动。

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In low Earth orbit, say 220 miles (355 km) up, where most human space travel takes place, a single circuit is completed in a much brisker 90 minutes.

在近地轨道，例如高于地球表面220英里(355公里)处大多数人类太空旅行发生的地方，运行一圈则需要更短的90分钟。

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