1976

Vikings on Mars

The short but successful mission of the Mariner 9, in 1971, formed the basis of a new NASA project to explore Mars in greater detail than ever before. The project was called Viking, and its goals were to launch two orbiters and two landers to Mars to significantly enhance our knowledge of the Red Planet’s surface, atmosphere, and potential as a past or present abode of life.

Launched in August and September 1975, the Viking 1 and Viking 2 probes arrived at Mars in June and August 1976, respectively. During the first month in orbit, the Viking 1 team took photos of the surface, searched for a safe place to deploy the nuclear-powered lander, and eventually chose a flat region known as Chryse Planitia (Plains of Gold). Viking Lander 1 set down safely on July 20, 1976, becoming the first successful mission to the surface of Mars. Viking Lander 2 successfully landed a few months later about 3,000 miles (4,800 kilometers) away, in flat and rocky Utopia Planitia.

With a cost of about $1 billion, Project Viking was the most complex and expensive Mars mission attempted up to that time, and it was a phenomenal success. The orbiters provided detailed, global maps of the surface, down to hundreds-of-meters-or-better resolution, revealing ancient water-carved valley networks, finely layered polar cap deposits, and details of the younger volcanic mountains and giant canyons discovered by Mariner 9. The idea that early Mars may have been warmer, wetter, and more Earthlike was based on Viking orbiter data.

A model of the Viking orbiter, including the entry capsule at bottom that housed the lander. The probe, including solar panels, was about 30 feet (9 meters) across.

The landers also developed a lasting paradigm for Mars studies. Meteorology experiments provided detailed information on the (hostile to humans) surface conditions and weather patterns. Most important, however, the landers’ search for evidence of organic molecules—potential indicators of life, or at least of habitable environments—came up empty. The setback for astrobiologists was temporary, however, helping to refine new experiments for future missions.

Viking Lander 2 image of the reddish, boulder-covered surface of Utopia Planitia, where it landed on September 3, 1976.