The Viking lander would be a much more complicated than the robot Surveyor that went up in the mid 1960's to the moon. Unlike Surveyor, the Viking lander would have to pass through the atmosphere before it lands. In addition all of the lander would have to be carefully sterilized to destroy any of Earth's microorganisms trying to catch a ride to Mars.

The lander spacecraft consisted of 5 basic systems. The first one would be the lander itself. It would be shaped as a hexagon with 3 long sides and 3 short sides, would give it a triangular shape with the three corners snipped off. The box would be made of titanium and aluminum alloys and would provide support for scientific experiments, communication instruments, and landing rocket engines. 3 extending legs would come out from the short sides. At the end of the legs would be 12-inch circular footpads.