Soil Moisture and Ocean Salinity
SMOS (Soil Moisture and Ocean Salinity) is one of ESA’s Earth Explorer missions. It is the first mission to provide global observations of the temporal and spatial variability in soil moisture and sea surface salinity, which are driven by the continuous exchange in Earth's water cycle between the oceans, atmosphere and land.
The MIRAS (Microwave Imaging Radiometer using Aperture Synthesis) instrument is a passive microwave 2-D interferometric radiometer (L-Band, 1.4 GHz, 21 cm) onboard the SMOS satellite. It picks up faint microwave emissions from Earth's surface to map levels of soil moisture, sea surface salinity, sea ice thickness and other geophysical variables, such as wind speed over the ocean and freeze/thaw soil state.
MIRAS consists of a central structure and three deployable arms. The 69 LICEF (Lightweight Cost-Effective Front-end) receivers are equally distributed over the three arms and the central structure. Each LICEF is an antenna-received integrated unit that measures the radiation emitted from Earth at L-band. The acquired signal is transmitted to a central correlator unit, which performs interferometry cross-correlations of the signals.