SOLAR SYSTEM

Detailed explanation-1: -When did Viking 1 and 2 launch? Viking 1 launched on August 20, 1975. It arrived in Mars orbit on June 19, 1976 and the lander touched down on July 20, 1976. Viking 2 launched less than a month after Viking 1 on September 9, 1975.

Detailed explanation-2: -When Viking 1 and 2 touched down on Mars in 1976, each carried several instruments to study the planet and look for signs of life. The Labeled Release experiment mixed small samples of Martian soil with drops of water containing a nutrient solution and some radioactive carbon.

Detailed explanation-3: -These experiments discovered unexpected and enigmatic chemical activity in the Martian soil, but provided no clear evidence for the presence of living microorganisms in soil near the landing sites.

Detailed explanation-4: -On July 20, 1976, the Viking 1 lander separated from the orbiter, touched down on the Chryse Planitia region of Mars, and sent back the first close-up photographs of the rust-colored Martian surface.