Viking 1 landed on Mars in 1976 and just a few months later, Viking 2 landed also on Mars.

海盗1号飞船于1976年登陆火星，仅仅几个月以后，海盗2号飞船也登陆火星。

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On July 20, 1976, spacecraft Viking 1 captured this, the first photograph ever taken of the surface of Mars.

1976年7月20日，海盗- 1号捕捉到有史以来第一张火星表面图。

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Last week Opportunity surpassed Viking 1 as the longest running mission on Mars, now extending well over six years.

上周机遇号超越了海盗1号成为火星上运行时间最长的任务，至今运行时间已延长了六年。

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There have been three successful Mars lander missions, the Viking 1 and Viking 2 in 1976, and the Pathfinder in 1997.

CNN: Mars Pathfinder enlisted in search for lost Polar Lander

There were three biology experiments on the Viking lander 1 and Viking lander 2.

NPR: Revisiting the Viking Missions to Mars

When the Viking lander 1 landed on July 20, 1976, it sent back the first pictures from the surface of Mars.

NPR: Revisiting the Viking Missions to Mars