In 2016, scientists at Goddard Space Flight Center (GSFC) produced mirrors with the highest reflectance ever reported in the farultraviolet (FUV) spectral range (100-200 nm). To develop these mirrors, the team developed a new three-step physical vapor deposition process to coat aluminum mirrors with protective magnesium fluoride (MgF²) or lithium fluoride (LiF) films to protect the aluminum from naturally occurring oxidation and boost its reflectance performance in the FUV.