Tianlian I (Simplified Chinese: 天链一号, Traditional Chinese: 天鏈一號, English: Sky Chain), also known as Tian Lian 1, TL-1, and CTDRS-1 is a Chinese data tracking and relay communications satellite series. Based on the DFH-3 satellite bus, it will provide communication coverage for manned Shenzhou missions, from Shenzhou 7 onwards. In terms of function, it is similar to the United States Tracking and Data Relay Satellite System.
The first satellite Tianlian I-01 of the series was launched on the maiden flight of the Long March 3C carrier rocket, at 15:35 GMT on 25 April 2008, from LC-2 at the Xichang Satellite Launch Centre. Tianlian I-01 will be able to cover around half of the spacecraft's trajectory, compared to around 12 percent which was previously covered using tracking stations and a fleet of ships. Tianlian I-02 was launched in July 2011 and Tianlian I-03 was launched on 25 July 2012. The satellite is in geostationary orbit.
Tianlian-1 satellites 
See also