global positioning system

By admin_wla | Tue, 4 Feb 2014 - 12:13
A system consisting of 25 satellites in 6 orbital planes at 20,000 km altitude with 12 hr periods, used to provide highly precise position, velocity and time information to users anywhere on Earth or in its neighborhood at any time. Source: NASA (http://earthobservatory.nasa.gov/Glossary)