The Viking 1 lander touchs down on Mars' Chryse Planitia (the Plains of Gold), becoming the first spacecraft to land safely on another planet.

Viking 1 and Viking 2, which lands about 45 days later in a different location, take photographs and collect other science data on the Martian surface. The landers conduct three biology experiments designed to look for possible signs of life. These experiments discover unexpected and enigmatic chemical activity in the Martian soil, but provide no clear evidence for the presence of living microorganisms in soil near the landing sites.

Meanwhile, the orbiters continue imaging and between them, image the entire planet at what was then high resolution. The orbiters also conduct atmospheric water vapor measurements and infrared thermal mapping. Viking 1 orbiter also flies within 90 kilometers (56 miles) of Phobos to take images of this larger, inner moon of Mars.

See also: National Space Science Data Center

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