The Skylab space station in orbit, 1973.

Skylab was launched on 14th May 1973 and was America's first manned orbiting space station. Visiting crews of three astronauts performed experiments to study the Sun, Earth and the impact of life in orbit on the human body. Three crews visited Skylab during its working life, with the astronauts on the last mision launched in February 1974 staying in orbit for 84 days. Skylab was intended to have two solar panels to supply electrical power to the station, but when the station arrived in orbit in 1973, one was found to be mising, while the other had not deployed. The first crew to visit the station made a spacewalk and were able to deploy the panel, restoring power to Skylab. The absence of the mising panel can clearly be seen in this picture.