Viking’s Mars shockers in 5 quick cards

Viking 1 landed in eastern Chryse Planitia on 20 July 1976, and Viking 2 on 3 September 1976.

The first color images from the Viking 1 lander showed cinnamon-red dirt, gray rocks, and a blue sky.

When the images were corrected, Mars' sky turned dusky pink with wind-borne dust.

The instruments returned identical equivocal readings.

Together, the Viking 1 and Viking 2 orbiters returned more than 51,500 images, mapping 97 percent of Mars.