Launched in 2009, Soil Moisture and Ocean Salinity (SMOS) was the second Earth Explorer Opportunity mission to be developed as part of the ESA (European Space Agency) Living Planet Programme. SMOS data furthers our knowledge of Earth's water cycle and advances weather and extreme-event forecasting, as well as seasonal-climate forecasting. As a secondary objective, SMOS provides observations over regions of snow and ice, contributing to studies of the cryosphere.