As we count down to the much-anticipated landing of NASA's six-wheeled Mars Science Lab (MSL) on Aug. 5/6th, it's noteworthy that 36 years ago today mankind made the first successful touchdown on the Red Planet.

The nuclear-powered Viking 1 lander settled down in a burst of retrorocket fire on a smooth circular plain close to the great volcanic Tharsis Bulge on July 20, 1976. Four billion years ago this region may have been a water-filled bay on Mars.

Viking's first black-and-white image (above) of a footpad resting on an alien planet transfixed the world.

Viking 1 was shutdown in 1982, but its legacy is as alive as ever today. Viking 1, and its sister robot, Viking 2, were the only two spacecraft ever dispatched to Mars with miniature onboard biological laboratories that performed the first in-situ experiments to find extraterrestrial life.

Though sending such a payload to what was then a largely unknown planet seemed premature, it does reflect NASA's aggressive spirit of exploration from the glory days of the 1960s and early 70s.

One out of three independent miniature experiment labs aboard the Vikings yielded positive results, as established by the rules of its builders.

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