THE Earth is bathed with signals from the network of Global Positioning System satellites, but few realise that the GPS signals that are reflected back into space contain a wealth of information about the planet. Now scientists are proposing a network of inexpensive satellites that could use these echoes to monitor some of Earth’s vital signs.
Using only reflected GPS signals, the new satellites could measure soil moisture content, ocean salinity and currents, and ocean surface wind speeds. They could also help reduce the amount of expensive equipment needed on other remote-sensing satellites, such as those that measure sea surface…
