NASA's Soil Moisture Active Passive (SMAP) platform uses a combined high-resolution L-Band Radar and L-Band radiometer to measure surface soil moisture and freeze-thaw state, providing for scientific advances and societal benefits. Direct measurements of soil moisture and freeze/thaw state are used to improve our understanding of regional water cycles, ecosystem productivity, and processes that link the water, energy, and carbon cycles. Soil moisture information at high resolution enables improvements in weather forecasts, flood and drought forecasts, and predictions of agricultural productivity and climate change.  

The main active radar instrument stopped transmitting on July 7, 2015. SMAP's radar allowed the mission's soil moisture and freeze-thaw measurements to be resolved to smaller regions of Earth—about 5.6 miles (9 kilometers) for soil moisture and 1.9 miles (3 kilometers) for freeze-thaw. Without the radar, the mission's resolving power will be limited to regions of approximately 25 miles (40 kilometers) for soil moisture and freeze-thaw. The mission will continue to meet its requirements for soil moisture accuracy and will produce global soil moisture maps every two to three days.

 Data for SMAP's L-Band Radar are available up until the date it stopped functioning.