Half hemisphere of the planet Mars, 1976.
© National Aeronautics & Space Administration / Science & Society
Photographed by one of the Viking spacecraft. One of the polar ice caps can clearly be seen on the right. Two Viking spacecraft were launched towards Mars by NASA in 1975, each carrying a lander spacecraft and an orbiter. Both succesfully landed their probes on Mars to study the Martian environment, soil constituents and to search for simple life forms. No evidence of life was found, but more recent studies of the Martian landscape suggest that in the past abundant surface water may have been present, which could have enabled life to exist. Today Mars has a very thin atmosphere, mainly of carbon dioxide, and no surface water appears to exist. There are permanent polar ice caps, made up of frozen water and carbon dioxide (dry ice).