Satellite telemetry that provides one of the most widely used methods for terrestrial, marine and avian GPS tracking, and can locate the data source from any location on Earth using the Doppler effect. A wide selection of Argos platforms exist: beacons for tracking animals, drifting or moored buoys, ice buoys, subsurface drifting floats. The Argos system collects data from Platform Terminal Transmitters, PTTs, and distributes sensor and location data to the final users. Argos helps the scientific community to better monitor and understand our environment, but also enables industry to comply with environmental protection regulations implemented by various governments. To meet system use requirements, all programs using Argos have to be related in some way or other to environmental protection, awareness or study, or to protecting human life. Applications for which there is a clear governmental interest are also approved.