“信使”号探测器在六年半前开始了它的太阳系之旅，直到今年三月十八日才进入水星轨道。

The Messenger began its trip through the inner solar system six and a half years ago, and it entered orbit around Mercury on March 18.

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(美国)宇航局称，NASA的一个航天器开始绕水星轨道航行，成为第一个环绕太阳系最内侧行星飞行的航天器。

A NASA spacecraft began orbiting Mercury, becoming the first to fly around the solar system's innermost planet, the space agency said.

youdao

(美国)宇航局称，NASA的一个航天器开始绕水星轨道航行，成为第一个环绕太阳系最内侧行星飞行的航天器。

NASA spacecraft began orbiting Mercury, becoming the first to fly around the solar system's innermost planet, the space agency said.

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