Martian landscape taken by one of the Viking spacecraft, 1976.
© National Aeronautics & Space Administration / Science & Society
The image shows a red rock-strewn terrain with a pink sky. Two Viking spacecraft were launched towards Mars 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 - none were found.