This video describes the Barbara A. Mikulski Archive for Space Telescopes (MAST), located at the Space Telescope Science Institute in Baltimore, Md. The archive holds data from 16 NASA telescopes, including current missions such as the Hubble Space Telescope and Kepler, a space-based observatory hunting for planets around other stars. Data from retired missions such as the International Ultraviolet Explorer, an ultraviolet-light satellite that ended its 18-year run in 1996, also are housed in MAST. The archive is NASA's repository for all of its optical and ultraviolet-light observations, some of which date to the early 1970s. At present, the archive contains nearly 200 terabytes of data.