The Global Positioning System (GPS) has three parts: the space part, the user part, and the control part. The space part consists of 24 satellites in orbit 11,000 nautical miles (20,300 kilometers) above Earth. The user part consists of a GPS receiver, which may be hand-held or mounted in a vehicle. The control part consists of five ground stations worldwide to assure the satellites are working properly. Using a GPS receiver an individual can determine his or her location on or above Earth to within about 300 feet (90 meters).