CHINA launched the last satellite of the BeiDou Navigation Satellite System(BDS),the 55th in the BeiDou family,on June 23 in Xichang Satellite Launch Center in Sichuan Province.It marks the completion of the deployment of China’s own global navigation system.On its journey to explore a path of developing a navigation satellite system suitable for its national conditions since the late 20th century,China formulated a three-step strategy of development for BDS:to complete the construction of BDS-1 and provide services to the whole country by the end of 2000;to complete the construction of BDS-2 and provide services to the Asia-Pacific region by the end of 2012;and to complete the construction of BDS and provide services worldwide around 2020.