Theory:

The National Aeronautics and Space Administration’s consisted of two spacecraft, named Viking 1 and Viking 2. The two identical spacecraft, Viking 1 and Viking 2, contained a lander and an orbiter. The main motives of the Viking Mission were to collect images and samples of the Martian surface and soil and search for the chance of signs of life on Mars.

Besides taking images and collecting other science data’s on the Martian surface, the two landers conducted three biology experiments to look for the possibility of signs of life. These experiments discovered unexpected and mysterious chemical activity in the Martian soil but provided no clear evidence for living microorganisms in the soil near the landing sites. According to scientists, Mars is a self-sterilising planet. They believed that the combination of solar ultraviolet radiation that saturates the surface, the extreme dryness of the soil, and the soil chemistry’s oxidising nature prevent the formation of living organisms in the Martian soil.
 
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Viking spacecraft*
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