Optical engineer examining two test mirror segments of the James Webb Space Telescope (JWST). The JWST is an infrared telescope that is scheduled to be launched in October 2021. It will be positioned near the Earth-Sun L2 Lagrangian point. It will study the formation of stars and planetary systems, and the history of the universe. By using infrared wavelengths, the JWST will be able to see through much of the dust that obscures visible light. It will also study dark matter, which is thought to form the majority of the matter in the universe. Photographed at NASA's Goddard Space Flight Center, Greenbelt, Maryland, USA.