November 13，1971， The American space probe, Mariner 9, has become the first spacecraft to orbit another planet, swinging into its planned trajectory around Mars without a hitch.

1971年的11月13日，美国宇宙飞船水手九号顺利进入火星的计划轨道飞行，成为首架环绕另一颗行星飞行的宇宙飞船。

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Dry channels on the Martian surface were first spied by Mariner 9 in 1971.

NPR: Radar Reveals Apparent Buried Channels On Mars

NASA's Mariner 9 and two Soviet orbiters arrived in May 1971 to find a global-wide dust storm in progress.

MSN: History littered with failed Mars probes

But a later mission, Mariner 9, showed in 1971 that the surface had extensive sand dunes, massive craters and huge lava flows.

ECONOMIST: Martian chronicles