The Viking program consisted of two identical spacecraft - Viking 1 and Viking 2 - launched in 1975 to study Mars. Each spacecraft was composed of an orbiter to photograph Mars from orbit and a lander to study the surface. The orbiters' objectives were to transport the landers, locate landing sites, and relay communications. The landers studied the soil with biological experiments, one of which produced a positive result but was inconsistent with other experiments that found no organic molecules in the soil. The program's results on the detection of life on Mars remain inconclusive.