Satellites
Satellites built for remote sensing purposes, have on board sensors or scanners that are able to detect different types of electromagnetic radiation. Different satellites have different sensors. Detected wavelengths include different types of microwaves, visible light, infra red radiation and radar and many more. (See section on electromagnetic radiation) Some satellites, so-called active sensors, are also equipped to send out their own energy signals. These signals are absorbed, reflected or scattered at the planet’s surface, and the sensor records the returned signals.
This section will provide more in-depth information about some satellite programmes, and includes links to external sites.