ZiYuan (ZY, “Resources”) is a series of Earth-observation remote-sensing satellites developed by China Academy of Space Technology (CAST) for both civil and military users. The programme began in the late 1970s as the Shijian 3 remote-sensing satellite, and later evolved into a multi-project satellite programme to provide medium- to high-resolution Earth imagery for territorial surveying, environment monitoring, city planning, crop yield assessment, disaster monitoring purposes, mapping, and survey roles. The first of the series, ZiYuan 1, later evolved into the China-Brazil Earth Resource Satellite (CBERS) programme, while China continued to introduced the Ziyuan 2 and 3 series under separate programmes.
Name:...............Ziyuan (ZY) Discipline:.........Imaging / optical Type:...............Government / military No. of missions:....6 (excluding CBERS satellites) First mission.......2000 Last mission........2016 Sponsor agency......Ministry of Land & Resources (MLR) Contractor(s).......CAST (prime) 508 Institute (electro-optical payload)
Governments of China and Brazil signed an agreement for the joint development of the Ziyuan 1 (ZY-1, also known as CBERS) satellite in 1988, and the first satellite CBERS-1 (Ziyuan 1-01) was launched in October 1999. The was followed by CBERS-2 (Ziyuan 1-02) in 2003, and CBERS-2B (Ziyuan 1-02B) in 2007. China subsequently developed Ziyuan 1-02C as a Chinese only project with no Brazilian involvement. The satellite was launched on 22 December 2011 and has been operated by the Chinese Ministry of Land and Resources (MLR). China-Brazil joint development subsequently resumed with the launch of CBERS-3 (Ziyuan 1-03) in 2013 and CBERS-4 (Ziyuan 1-04) in 2014.
Ziyuan 1-02C featured two high-resolution panchromatic CCD cameras with a spatial resolution of 2.36 metres and a joint ground swath of 54 km, and an infrared multispectral scanner (IRMSS) camera with a spatial resolution of 5 metres (panchromatic mode) or 10 metres (colour imagery) and a ground swatch of 60 km.
Satellite bus:......CAST Phoenix Eye Mass:...............1,450 kg Dimensions:.........2.00 m x 1.80 m x 2.25 m Solar panel span:...N/A Orbit:..............778 km Inclination:........98.6º Stabilisation.......3-axis Designed life.......2 years
Ziyuan 2 (ZY-2) was a medium-resolution remote-sensing satellite with both civil and military roles, and was reportedly known as JianBing 3 in its military designation. The satellite was designed to operate on an 800 km Sun Synchronous Orbit (SSO), collecting Earth imagery with a spatial resolution of 3 metres and a ground swath width of 30 km. The image data could be stored on the satellite or transmitted directly to ground station. The onboard camera could be swung to either side, allowing it to point to different targets rapidly. The satellite also had the orbit manoeuvre ability in order to cover different regions on Earth.
Ziayun 2 was the largest and heaviest satellite ever built by China at the time of its launch. With its improved imaging system and star-sensor three-axis stabilisation technology, the satellite was also the most advanced and capable remote-sensing satellite ever developed by China at the time. However, it could only capture images of 3 m resolution in the visible spectrum, meaning that it was still generations behind those introduced by Western countries and Russia.
Development of the imaging system for the Ziyuan 2 began in 1993, and the engineering development of the satellite began in 1996. Ziyuan 2 was the first spacecraft to have been built in the space fabrication facility inside “Beijing Aerospace City”, a spaceflight operations and manufacturing complex located in northwest suburbs of Beijing.
The first satellite of Ziyuan 2 was launched by a CZ-4B launch vehicle from the Taiyuan Satellite Launch Centre on 1 September 2000. The satellite had a designed operational lifespan of two years, but remained operational in orbit for more than four years. It was followed by two subsequent satellites with similar design and payload in 2002 and 2004.
Satellite bus:......CAST Phoenix Eye Mass:...............N/A Dimensions:.........N/A Solar panel span:...N/A Orbit:..............500 km Inclination:........94.4º Stabilisation.......3-axis Designed life.......2 years
Ziyuan 3 (ZY-3) is a civil high-resolution survey and mapping satellite, designed and built by CAST for the Chinese Ministry of Land and Resources (MLR). The MLR began to develop the concept of a high-resolution survey satellite for mapping role in 2005, and the ZiYuan 3 project was officially approved by the Chinese government in 2008. Engineering development of the satellite began in 2009. The first satellite was launched in 2012, followed by a second satellite 2016.
Ziyuan 3 was based on the three-axis stabilised Phoenix Eye satellite bus developed by CAST, with a designed life of 4 to 5 years. Ziyuan 3 has a launch mass of 2,630 kg, and is fitted with a pair of solar panels and a unified S-band (USB) telemetry, tracking and control (TT&C) subsystem. The satellite operates on a 506 km SSO, and could cover all areas on the Earth surface between 84°N and 84°S latitude every 59 days.
The satellite is equipped with an electro-optical payload package designed by Beijing Institute of Space Machinery and Electronics (508 Institute). The package was designed to obtain three-dimensional images of the Earth using three high-resolution panchromatic cameras positioned 22° from each other to face forward, vertical to ground, and rear. The front- and rear-facing cameras had a spatial resolution of 4.0 m and 52.3 km ground swath. The ground-facing camera had a spatial resolution of 2.5 m and 51.1 km ground swath width. Additionally, the package also included an infrared multispectral scanner (IRMSS), which had a ground resolution of 10 m and 51 km ground swath width.
Satellite bus:......Phoenix Eye Mass:...............2,630 kg Dimensions:.........N/A Solar panel span:...7.529 m Orbit:..............506 km Inclination:........97.4º Stabilisation.......3-axis Designed life.......4 to 5 years