Compass-IGSO1, also known as Beidou-2 IGSO1 is a Chinese

People's Republic of China

China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

 navigation satellite which will become part of the Compass navigation system

Compass navigation system

The COMPASS system is a project by China to develop an independent global satellite navigation system.COMPASS is not an extension to the previously deployed Beidou-1, but a new GNSS similar in principle to GPS, GLONASS, and Galileo.-General:The new system will be a constellation of 35 satellites,...

. It was launched in July 2010, and became the fifth Compass satellite to be launched after Compass-M1, G2, G1

Compass-G1

Compass-G1, also known as Beidou-2 G1 is a Chinese navigation satellite which will become part of the Compass navigation system. It was launched in January 2010, and became the third Compass satellite to be launched after Compass-M1 and Compass-G2....

, and G3.

Compass-IGSO1 was launched at 21:30 GMT on 31 July 2010. The launch used a Long March 3A

Long March 3A

The Long March 3A , also known as the Chang Zheng 3A, CZ-3A and LM-3A, is a Chinese orbital carrier rocket. It is a 3-stage rocket, and is usually used to place communications satellites and Beidou navigation satellites into geosynchronous transfer orbits.It has formed the basis of the Long March...

 carrier rocket, flying from the Xichang Satellite Launch Centre. The satellite is developed in the basis of the DFH-3 satellite platform and has a lifespan of 8 years.

Instruments

The primary instrument aboard Compass-IGSO1 is navigation system operating in L-band. Compass-IGSO1 is the second satellite of Compass navigation system with optical synchronization link. Space segment of an instrument called Laser time transfer (LTT) consists of corner-cube retroflectors array (hexagonal shape 49 × 43 cm, 90 pcs, 33 mm diameter, 770 cm² reflective area) and single-photon avalanche diode

Single-Photon Avalanche Diode

In optoelectronics the term Single-Photon Avalanche Diode identifies a class of solid-state photodetectors based on a reverse biased p-n junction in which a photo-generated carrier can trigger an avalanche current due to the impact ionization mechanism...

 based detector developed in cooperation with CTU

Czech Technical University in Prague

Czech Technical University in Prague is one of the largest universities in the Czech Republic, and the oldest institute of technology in Central Europe....

. The ground segment is the dedicated Chinese satellite laser ranging

Satellite laser ranging

In satellite laser ranging a global network of observation stations measure the round trip time of flight of ultrashort pulses of light to satellites equipped with retroreflectors...

network. The combination of traditional passive laser ranging with active single photon detection aboard is producing data for ground-to-space oscillator time-base with 10⁻¹¹ s precision.