A constellation of Earth-observing radar minisatellites to monitor disasters and for environmental protection that form a national program by the National Committee for Disaster Reduction and State Environmental Protection Administration of China (Huan Jing means ‘environment’). The mission comprises three minisatellites. Two were launched on 5 September 2008, into a Sun-synchronous polar orbit at an altitude of 649 km, and the third on 19 November 2012, at an altitude of 499 km, all from the Taiyuan Satellite Launch Center.