A class of artificial earth satellites. Launch is intended for practical application, the ground is named after. Two types: (1) civilian type. Meteorological, communications, broadcasting, surveying, navigation, earth resources satellites; (2) military type. Meteorological, communications, photographic reconnaissance, electronic reconnaissance, surveying, navigation, nuclear explosion monitoring, missile warning, maritime surveillance, anti-satellite and other satellites, or interference with security measures such as remote sensing and higher accuracy requirements.