From the "Viking Archive" - Viking 2: full panorama

Caption NASA originale:"The Viking Lander 2 site in Utopia Planitia has more and larger blocks of stone than does the Viking Lander 1 site in Chryse Planitia. The stones are probably ejecta from impact craters near the Lander 2 site. Many of the rocks are angular and are thought to be only slightly altered by the action of wind and other forms of erosion. Drifts of sand and dust are smaller and less noticeable at the Lander 2 site. The overall red/orange coloring of the Martian terrain is due to the presence of oxidized iron in the regolith. The pink color of the sky is caused by extremely fine dust that is suspended in Mars' thin atmosphere".

Nota: 1) il cielo, in questa immagine in "almost true colors", noi lo vediamo verdastro e non rosa; 2) se l'atmosfera Marziana fosse davvero sottilissima, il cielo dovrebbe apparire MOLTO più SCURO di quanto invece non appare nelle immagini (rosso/arancio scuro nelle ore del giorno pieno - e cioè fra le 10 e le 15 MLT -, azzurro scuro con il "dimming").