On Tuesday, China launched the final satellite in its BeiDou Navigation Satellite (BDS) System, marking the completion of its homegrown GPS-esque navigation system. The project has been decades in the making. It began in the 1990s, and the first satellite launch was in October 2000, according to Space.com. BDS is currently one of four global navigations systems. The others are the U.S. government-run GPS, Russia’s GLONASS, and the European Union’s Galileo.