The Soil Moisture Active-Passive (SMAP) mission has been recommended by the NRC Earth Science Decadal Survey Panel for launch in late 2014. SMAP will combine low-frequency microwave radiometer and radar 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 needed 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.
A novel approach combining radar-radiometer and L-band mapping of global soil moisture will allow SMAP to exceed current operational measurements sensing depth and spatial resolution. The mission is expected to acquire these measurements for at least three years with global coverage of both soil moisture and freeze/thaw status provided every two to three days.