Crystal growth in space. Historical image of a crystal of germanium selenide (GeSe), a semiconductor, grown in space in April 1974. The crystal was grown by vaporizing and condensing GeSe powder in a sealed ampule in an electric furnace on board the Skylab space station. The experiment was conducted as a comparative test of GeSe crystals grown on Earth and those grown in a weightless environment. The results indicated that crystals grown in zero-gravity demonstrate greater growth and better composite structure than those grown in ground-based laboratories. The GeSe crystal shown here is 20 millimetres long.