The power of most precision-farming applications comes from the integration of “eyes in the sky” satellites with the traditional farming tool kit. For space age farming, two classes of satellites do the heavy lifting: Global Positioning System (GPS) satellites offer guidance and navigation, and Earth-observation satellites generate surface pictures of the land and seas.
Operated by the U.S. Department of Defense, a constellation of some 24 GPS satellites transmits precise time and orbit information, which translates into latitude and longitude. An individual with a hand-held GPS device can determine his or her location on Earth to within 20 metres. For much of what farmers want to do, however, that’s not close enough. For greater precision, tractors can be outfitted with an additional receiver for “differential GPS,” which can give coordinates to within one centimetre, depending on the type of GPS unit.
Earth-observation satellites, such as Canada’s RADARSAT, provide a reliable assessment of environmental change, from the spread of pollution across a continent to the path of a hurricane. More than 60 high-tech environmental satellites continuously scan the planet, showing the world through a wide frame so that large-scale phenomena can be observed accurately. And because Earth-observation satellites remain in place for long periods of time, they are able to highlight environmental changes that are occurring gradually, which is particularly useful when studying soil conditions.
Besides operating RADARSAT-1, the Canadian Space Agency is a partner in other international satellite projects, such as SMOS (Soil Moisture and Ocean Salinity), that offer unique and invaluable information to farmers.
This piece features an animated diagram explaining how Earth observation satellites work, and the difference between active and passive sensors. It also explains the difference between geosynchronous satellites and satellites used for surveillance and environmental monitoring.