Viking at Mars: 30 Years Later

Thirty years ago, NASA's Viking landers made history by descending from orbit to the surface of Mars -- the first probes from Earth to land intact on another planet.

The first probe, Viking 1, arrived in Mars orbit on June 19, 1976. The lander touched down on July 20, exactly seven years after Apollo landed the first humans on the Moon.

Working steadily for years beyond their planned life expectancy, the landers accumulated 4,500 up-close images of the Martian surface. The Viking orbiters high above snapped over 50,000 images, mapping 97 percent of the Martian globe. Successful in so many ways, Viking is best remembered for the first space probes to conduct on-the-spot biological tests for life on another planet.