Half a century after the first successful Mars landing, Viking's greatest legacy may be the questions it taught us to ask.

NASA's Viking 1 mission blazed a crucial trail with its Mars landing on July 20, 1976. Now, half a century later, that trail ...

This Viking 1 image is one of first images of a sunset as seen from the surface of Mars. It shows the Chryse Planitia region ...

Half a century after NASA first placed working hardware on Mars, the agency is preparing to explore not only the planet’s surface, but its skies. The story began on July 20, 1976, when Viking 1 ...