Over a dozen radio signals that have hindered data collection on ESA's SMOS water mission have been switched off. The effort also benefits satellites such as NASA's Aquarius mission, which measures ocean salinity at the same frequency.
We all know what happens when you place a cell phone too close to a speaker: seconds before the phone rings, that obnoxious buzz interrupts your favourite song. This is radio interference an unwanted reception of radio signals. Not only can it interrupt the music from your stereo, it can also impede satellite measurements.
ESA's Soil Moisture and Ocean Salinity (SMOS) satellite was launched in 2009 to improve our understanding of our planet's water cycle. In order to do this, it measures the microwaves emitted by Earth in the 1400-1427 MHz range.
SMOS immediately revealed that many unlawful signals were being transmitted around the world in this frequency range, rendering some of its measurements unusable for scientific purposes.
Over the years, ESA has investigated exactly where the interference is coming from.
As national authorities have collaborated with ESA to pinpoint the origin and switch these unlawful emissions off, the interference has waned.
One of the largest areas of contamination in the northern hemisphere is over the North Pacific and Atlantic oceans, primarily from military radars.
Over recent years, authorities from Canada and Greenland have been asked to take action. Canada started to refurbish their equipment in late 2011, while Greenland switched off their transmitters in March 2011.
At least 13 sources of interference have now been switched off in the northern latitudes. This has significantly improved SMOS observations at these high latitudes, which were previously so contaminated that accurate salinity measurements were not possible above 45 degrees latitude as the satellite headed north.
However, the few remaining
|Contact: Robert Meisner|
European Space Agency