14 DAY TRIAL // When the European Space Agency (ESA) launched the Soil Moisture and Ocean Salinity (SMOS) satellite in 2009, it had received approval to conduct measurements in the 1400–1427 MHz range, which belongs to the microwave portion of the electromagnetic spectrum.
Unfortunately, as soon as the spacecraft reached orbit, it became apparent that a large number of unauthorized radio sources were broadcasting in this frequency range, preventing the vehicle's instruments from conducting accurate measurements of small changes in planetary parameters.
Thus far, ESA supervised the switch-off of more than a dozen such illegal signals. In addition to allowing SMOS to conduct more in-depth measurements, the action will also benefit other satellites operating at these wavelengths, including the NASA SAC-D/Aquarius mission.
The effect that these radio sources caused in SMOS data was similar to the distorted sounds coming from a speaker when a cell phone rings nearby. The annoying buzzing represents noise inserted into the clean signal, which distorts it, sometimes beyond recognition.
Immediately after SMOS' microwave instruments were turned on, it became apparent that a large number of unlawful radio sources polluted the 1400–1427 MHz range, from diverse locations scattered all around the world.
These interferences rendered some of the satellite data unusable for scientific purposes, so ESA decided to investigate the nature and sources of the pirate signals, eventually identifying their exact location.
National authorities around the globe worked together with the agency, collaborating in shutting down the illegal radio signals, and thus reducing the amount of interference SMOS' instruments experience.
Military radars across the North Pacific and Atlantic oceans were one of the most significant sources of interference. The Canadian and Greenlandic governments were asked to take action in this regard. While Canada refurbished the equipment in late 2011, Greenland switched it off altogether.
“Combining SMOS and Aquarius new observations will allow us to map ocean surface salinity with an unprecedented spatial and temporal resolution,” French Research Institute for Exploration of the Sea expert, Nicolas Reul, explains.
“In particular, salinity fronts and the movement of water across tropical oceans and within strong currents – such as the Gulf Stream – shall be better detected and tracked than with single-sensor observations,” he concludes.