Although not designed to deliver information on ice, ESA’s Earth Explorer SMOS satellite can detect thin sea-ice. By combining measurements from SMOS with measurements from CryoSat the two different satellites missions are yielding an even clearer picture of the changing Arctic. SMOS is also helping to improve the accuracy of sea-ice forecasts, which could help marine traffic operators determine the safest and most economic routes through waters such as the Northwest Passage and the Northern Sea Route as the ice becomes thinner owing to climate change.