Viking 2 Orbiter
The Viking mission consisted of launches of two separate spacecraft to Mars, Viking 1, launched on 20 August
1975, and Viking 2, launched on 9 September 1975. Each spacecraft consisted of an orbiter
and a lander. After orbiting Mars and returning images used for landing site selection,
the orbiter and lander detached and the lander entered the martian atmosphere and
soft-landed at the selected site. The orbiters continued imaging,
experiments and other scientific operations from orbit while
the landers deployed instruments on the surface. The fully fueled orbiter-lander pair had
a mass of 3527 kg. After separation and landing, the lander had a mass of about 600 kg and
the orbiter 900 kg.