Satellite navigation signals already help cruise missiles to find their targets and hungry motorists their way to the nearest fast-food joint. Now it turns out they can also be used to seek out a valuable resource: water.
The fleet of satellites making up the Global Positioning System (GPS) bathes the Earth in weak microwave signals. When these signals bounce off the ground, their characteristics change in ways that convey information about the soil’s moisture content. There has been speculation for a decade that it might be possible to exploit this effect, and now researchers at the University of Boulder in…
