The Medium-Range Discrimination Radar (MRDR) is a proposed sensor system and component of layered Ballistic Missile Defense System (BMDS) and Ground-based Midcourse Defense (GMD). The MRDR is a scaled-down version of the Long-Range Discrimination Radar (LRDR) which is set to go operational in 2020, at Clear Air Force Station, Alaska. “Discrimination” means that the radar can both detect and characterize ballistic missile threats. The S-Band radar is dual-polarized, meaning that it sends out vertical and horizontal radar waves which can differentiate between multiple targets, which may appear as one on traditional radar.
MRDR is needed to address the gaps in BMDS and better protect Hawaii. Currently, The United States relies on a layering of sensors to protect the west coast, including SPY-1 radar on Aegis ships, TPY-2 X-Band ground-based radar, and Cobra Dane surveillance radar in Shemya, Alaska. A key component of this layered system is the Sea-based X-Band radar. It roams the Pacific as an Early Warning System (EWS), but it is scheduled to be put in dry dock for maintenance in the next few years. Many believe the current system is sufficient, but susceptible to being overwhelmed. The objective is to place MRDR in Hawaii, so that it can detect threats early enough for the interceptors in Alaska and California to strike.