James Webb Space Telescope (JWST) cleaning. Engineers testing a carbon dioxide 'snow' cleaning process on a mirror segment for the James Webb Space Telescope. The 'snow' knocks contaminate particulates and molecules off the mirror segment without scratching it. The JWST is an infrared telescope that is scheduled to be launched in 2018. 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, thought to form the majority of the matter in the universe. Photographed in 2015 at NASA's Goddard Space Flight Center in Greenbelt, Maryland, USA.