From Science: In the undulating, dust-covered Descartes Highlands, 380 kilometers southwest of Tranquility Base, where Apollo 11 landed half a century ago, a lonely gold-plated telescope has sat inert since 24 April 1972, when Apollo 16 astronauts John Young and Charles Duke blasted off the surface and left it behind. It was a small part of their 3-day mission, but a milestone for astronomers: the first observatory on another world.
The designer of the telescope was George Carruthers, a young researcher at the Naval Research Laboratory in Washington, D.C., who had made his name building ultraviolet (UV) telescopes for sounding rockets, which make short flights above the UV-blocking atmosphere. A big question at the time was whether the hydrogen in interstellar gas clouds was made of individual atoms or molecules of hydrogen (H2). The answer lay in its UV spectrum, which is difficult to capture from a sounding rocket.