Major missions completed by NASA include Skylab, STS-85 and Apollo 12. Skylab was the first United States space lab launched by NASA over the course of 24 weeks in 1973-1974; obtained by three separate three-men crews to study Earth and many other experiments. STS-85 was a mission in 1997 carried out to study Earth’s middle atmosphere, the crew for the mission was made up of Curtis L. Brown Jr, Kent V. Rominger, N. Jan Davis, Robert L. Curbeam Jr, Stephen K. Robinson and Bjarni V. Tryggvason. Apollo 12 mission saw the second crew; Charles Conrad, Richard F. Gordon and Alan L. Bean land on the moon on November 19th, 1969. Apollo 12 was the sixth crewed flight in the United States Apollo programme and landed back on earth on November 24th, 1969.