China's first batch of Yaogan-31 optical satellites has been launched into space from the Jiuquan Satellite Launch Center in northwestern China. A Long March-4C rocket carried the satellites, marking the 271st mission for the Long March rocket family. The mission also sent an experimental nano technology satellite into orbit. The satellites will be used to survey the earth's electromagnetic environment and other similar studies. The Yaogan satellite series first launched in 2006.