According to, errant or illegal signals from ground-based radio transmitters have marred early data returns from the European Space Agency’s Soil Moisture and Ocean Salinity Satellite (SMOS), which launched in November and began science operations in May.

The SMOS instrument package is designed to collect natural radio signals emanating from the Earth’s surface that contain information on the properties of the land and sea. The instrument takes these measurements in an L-band frequency range that has been set aside by the International Telecommunication Union for science.

      “But the first global maps from SMOS show clusters of interfering signals scattered across southern Europe, the Middle East, India and China. The most offensive transmissions were coming from locations in or near cities like Madrid, Athens and Beijing.

      “According to ESA, the signals were either illegal transmissions within the SMOS frequency band or amplified interference from other bands leaking into the protected range.”