The Advanced Technology Microwave Sounder (ATMS) will provide along with CrIS; retrievals of atmospheric moisture and temperature profiles for the National Polar-orbiting Operational Environmental Satellite System (NPOESS). The first deployment of the ATMS is scheduled in late 2009 on the NPOESS Preparatory Project (NPP) satellite, which is an early instrument risk reduction component of the NPOESS mission. However this poster will focus on the development of the ATMS for C1, the first launch of NPOESS scheduled in 2009. This Poster will focus on some of the challenges to ATMS which revolve around new design aspects of ATMS resulting from performance and parts obsolescence challenges.