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.
Create your account to keep this answer and continue from it later.
Let's look at alternatives: