The development of cryogenic microwave components, such as focal plane polarization modulators, first requires an RF MEMS switching technology that operates effectively at cryogenic temperatures. The approach of this project is to explore the performance of capacitive MEMS switching technology at low temperatures. MEMS capacitive switches represent an alternative to ohmic contact switches, where the RF impedance of the device is not dependent on metal-metal contacts. These MEMS switches operate with much lower effective series resistance (generally ~ 0.25 ohms) and do not have the issues associated with dry contact switching. This technology also has the advantage of operating very well at millimeter-wave frequencies and higher, where many of the most demanding performance limitations exist. This technology has seen significant investment through DARPA and the DOD, and is directly applicable to high-performance microwave components needed in several of the upcoming NASA missions.