China launched its 5th Big Dipper navigation satellite onto the transfer orbit in Xichang on 1st August, the third of the Big Dipper series launched this year. An officer concerned explains that the Big Dipper navigation system is a GNSS independently developed and operated by China. After 19 years of development, it is playing a vital role in various fields including mapping, fishing, transportation, communications and so on, especially in earthquake relief work.