CBERS / Ziyuan 1
China-Brazil Earth Resource Satellite (CBERS) is an Earth-observation remote-sensing satellite programme jointly funded by China and Brazil. The satellite was designed to acquire medium-resolution (20 m) images of Earth in both visible and infrared spectrums for land survey, environment monitoring, and natural disaster evaluation purposes. The satellite was based on the Chinese ZiYuan 1 (ZY-1) bus, but added with Brazilian-designed mission payload.
- CBERS 1/2
- CBERS 3/4
- CBERS 5/6
- CBERS 7 (CBSAR)
Name:...............China Brazil Earth Resource Satellite (CBERS) Discipline:.........Imaging / optical Type:...............Commercial No. of missions:....5 (excluding ZY-1-02C) First mission:......1999 Last mission:.......2014 Sponsor agency:.....CAST / INPE Contractor(s):......CAST (prime) 504 Institute (CCD camera) 508 Institute (CCD camera, PanMUX, IRMSS, IRMSS-2) INPE (WFI, MUXCam, data management system , AOCS)
Early remote-sensing satellites were mostly film-returning type. The satellite imagery of Earth was captured on films and then returned in a re-entry capsule. The advance in the CCD camera and telecommunications technology allowed satellite imagery to be captured electronically and transmitted via a data link to the ground station. China Academy of Space Technology (CAST) began to develop a three-axis stabilised data-transmission type remote-sensing satellite ShiJian 3 (SJ-3) in 1979. This project later turned into the more sophisticated Ziyuan 1 with the ability to capture imagery in both visible and infrared spectrums in 1985.
504 and 508 Institutes of CAST developed a 400 mm 4-spetrum CCD camera and successfully tested it onboard an aeroplane in 1986. 504 Institute also developed the high-speed data transmission technology. 510 Institute developed the cooling system for the multi-spectrum infrared scanner. Despite these achievements, the ZiYuan 1 (ZY-1) project made little progress in its first year due to a lack of funding. In the same year, the State Council and the Ministry of Aerospace approved the ZY-1 project, but only agreed to fund half of the programme cost, while CAST was asked to find a sponsor to provide the other half of funding.
CAST initially approached France for assistance, but the negotiation produced no result. Soon they approached Brazil, who was also seeking the remote-sensing satellite technology. After a series of visits between the two sides, CAST and the Brazilian National Institute for Space Research (INPE) reached an initial agreement on 4 March 1988 for the joint development of a remote-sensing satellite known as CBERS, based on the Ziyuan 1 satellite design. The programme was approved by the governments of both countries on 6 July, when representatives of the two governments signed an official agreement in Beijing.
The CBERS programme has often cited by both countries as a prime example of space co-operations between developing nations. Brazil’s own space programme struggled to take off and had learned a great deal of knowledge and experience from the joint development. Through its co-operation with Brazil, China was able to access to some Western satellite technologies still being forbidden to be exported to China directly. China was also seeking to use its space technology and experience to open up new markets in Asia, Africa and South America, where the influence of other space powers was relatively weak. In 2009, China and Brazil agreed to supply CBERS data to African countries via the ground stations in South Africa, Egypt, and Spain. A ground station was also built in Hong Kong to serve users in Southeast Asia.
The first-generation CBERS 1/2 were equipped with a medium-resolution CCD camera, an infrared multispectral scanner (IRMSS) camera, and a wide-field imager (WFI) camera for capturing images in both visible spectrums and infrared spectrums. The CCD camera had a spatial resolution of 20 m and 113 km ground swath, and operated in five spectral bands. It could swing sideway 32° in either direction in order to capture different target rapidly. A complete coverage cycle of the CCD camera took 26 days.
The IRMSS had a spatial resolution of 78 m (short-wavelength infrared) or 156m (thermal imaging) and 120 km ground swath, and operated in four spectral bands. The WFI had a spatial resolution of 258 m and 890 km ground swath, and operated in two spectral bands. The images taken by the IRMSS and WFI could also be correlated with the images of the CCD camera to improve accuracy.
The 1,540 kg satellite was in a cube shape 2,000 x 1,800 x 2,250 mm in size. Power was supplied by a single solar panel, with an output of 1,100 W. The CAST Phoenix Eye satellite bus is three-axis stabilised. The spacecraft consisted of 8 sub-systems: space frame, power supply, S-band telemetry and tracking, altitude and orbit control, X-band data link and management, thermal control, electronic, UHF/VHF communications. The data transmission rate was 100 MB/s. CBERS 1 was launched on 14 October 1999, followed by CBERS 2 on 21 October 2003.
Satellite bus:......CAST Phoenix Eye Mass:...............1,540 kg Dimensions:.........2.00 m x 1.80 m x 2.25 m Solar panel span:...N/A Orbit:..............778 km Inclination:........98.5º Stabilisation.......3-axis Designed life.......2 years
The CBERS 2B project was agreed between China and Brazil in 2004, as a stopgap before CBERS 3 could be launched. CBERS 2B was similar in size to its two predecessors CBERS 1/2, but featured some improvements on its mission payload, including a high-resolution (HR) panchromatic camera (HRC) that replaced the IRMSS imager. The satellite was also equipped with a GPS receiver for high accuracy in orbit insertion. Integration and testing of CBERS-2B was carried out in INPE’s Integration and Testing Laboratory in São José dos Campos.
CBERS 2B was launched atop a CZ-4B launch vehicle from the Taiyuan Satellite Launch Centre on 19 September 2007. The satellite’s operation ended in April 2010.
Ziyuan 1-02C was based on the CBERS 1/2 design, but developed as a Chinese only project with no Brazilian participation. The satellite was China’s first operational civilian remote-sensing satellite, specifically designed for the Chinese Ministry of Land and Resources (MLR). The onboard observation package included two high-resolution cameras (HRC) and an infrared multispectral scanner (IRMSS) camera. The panchromatic cameras had a spectral resolution of 2.36 m and a joint ground swath of 54 km. The IRMSS had a spectral resolution of 5 m / 10 m and ground swath 60 km. The HRCs feature a lower compression rate (4:1) in its downlink transmission than that of the CBERS-2B (8:1), which allowed producing Earth images with better qualities. The satellite was successfully launched from Taiyuan on 22 December 2011.
Under a new agreement signed between China and Brazil in November 2002, the two countries would jointly develop the second-generation CBERS satellites as successors to CBERS 1/2. The satellite pair, named CBERS 3 and 4, would cost a total of US$300 million to develop. China and Brazil would each share 50% of the costs, and also be responsible for 50% of the development work. This allowed a greater participation by Brazil, whose involvement would include the development of onboard imagers as well as satellite assembly and testing in Brazil.
The CBERS 3/4 project was proved troublesome from the start. As a result of the global financial crisis that began in 2007, INPE saw its space programme budget being slashed by US$45 million in 2009. This coupled with technical difficulties and an embargo of electronic components imposed by the United States on China, resulted in some serious delay in the project. CBERS 3 was originally scheduled to be launched in 2009, but the launch date was repeatedly postponed. Brazil completed the electrical testing and thermal vacuum chamber testing of the satellite in 2012.
The satellite was 3.35 x 3.35 x 3.25 m in size (excluding the solar panel), with a total mass of 1,980 kg. It consists of two parts: service module and payload module. The payload mass was about 1,000 kg. All onboard cameras and communication antennas were mounted on the +Z side panel, pointing to Earth. Power was supplied by a three-panel solar wing, which was attached to the -Y side panel and rotated around the Y axis. The power supply output was 2,300 W. The satellite had a unified S-band (UBS) telemetry and tracking system. Its data downlink worked in the X-band, with two transmitters. The transmission rate was 305 MB/s. The onboard recorder had a memory capacity of 274 GB.
The satellite was three-axis stabilised by its altitude and orbit control (AOCS) system to ensure that the imagers were pointed to Earth. The system consisted of star sensors, Sun sensors, infrared Earth sensors, gyros, GPS receiver, a control computer, momentum wheels and a hydrazine propulsion system. The satellite used a passive thermal control with thermal coating, multi-layer insulation blankets, heat pipes and heaters.
The satellite’s mission payload included: Multispectral camera (MUXCam) developed by INPE; Wide-field imager (WFI) developed by INPE; Panchromatic and multispectral camera (PanMUX) developed by CAST; Infrared multispectral scanner-2 (IRMSS-2) developed by CAST.
The MUXCam used a pushbroom sensor with a spatial resolution of 20 m and 120 km ground swath, and operated in four spectral bands covering the wavelength range from blue to near infrared. It had no ability to swing sideway. A complete coverage cycle of the MUXCam took 26 days.
The PanMUX was a pushbroom CCD camera designed to provide panchromatic images with 5 m ground sample distance (GSD) and three band multispectral images with 10 m GSD. The camera had a swath of 60 km and a side swinging capability of +/-32°. The camera had focal plane adjustment and in-orbit calibration capabilities.
The WFI developed by INPE was an improved version of that onboard CBERS 1/2, featuring a spatial resolution of 64 m and a ground swath of 866 km.
CBERS 3 was launched atop a CZ-4B launch vehicle from the Taiyuan Satellite Launch Centre at 11:26 CST on 9 December 2013. However, the satellite failed to enter its intended orbit due to launch vehicle malfunction – another major setback for the project. The second satellite, CBERS 4, was successfully launched on 7 December 2014. A third satellite designated CBERS 4B is scheduled for launch in December 2018.
Satellite bus:......CAST Phoenix Eye Mass:...............1,980 kg Dimensions:.........3.35 m x 3.35 m x 3.25 m Solar panel span:...N/A Orbit:..............780 km Inclination:........98.5º Stabilisation.......3-axis Designed life.......3 years
CBERS 5 and 6 are the third-generation CBERS satellites currently in development. Its onboard mission payload will include a panchromatic multispectral (PANMUX) camera developed by CAST, an infrared multispectral imager (IRMSS) developed by CAST, multispectral wide field imager (MUX/WFI) developed by INPE, a programmable spectrometer developed by CAST, and a polarisation imager developed by CAST. The two satellites are scheduled to be launched between 2017 and 2020.
CBERS 7 (CBSAR)
INPE also revealed a concept of a synthetic aperture radar (SAR) satellite, debuted CBERS-7, or CBSAR. The L-band radar onboard the satellite would be capable of providing 3 metres spatial resolution of ground radar images in high-resolution mode and 30 metres in low-resolution mode.
|1979 — Shijian 3 project initiated. CAST began the development of a three-axis stabilised data-transmission type remote-sensing satellite Shijian 3.|
|1985 — Shijian 3 became Ziyuan 1. The Shijian 3 project turned into the more sophisticated Ziyuan 1 with the ability to capture imagery in both visible and infrared spectrums.|
|1986 — 400 mm 4-spetrum CCD camera succeeded. 504 and 508 Institutes successfully tested the CCD camera onboard an aeroplane. 504 Institute also developed the high-speed data transmission technology. 510 Institute developed the cooling system for the multi-spectrum infrared scanner.|
|1986 — Ziyuan 1 project approved. The State Council and the Ministry of Aerospace approved the Ziyuan 1 project, but only agreed to fund half of the programme cost, while CAST was asked to find a sponsor to provide the other half of funding.|
|1988 March 4 — CAST and INPE agreement reached. CAST and the Brazilian National Institute for Space Research (INPE) reached an initial agreement for the joint development of a remote-sensing satellite known as CBERS, based on the Ziyuan 1 satellite design|
|1988 July 6 — CBERS programme approved. Representatives of the Chinese and Brazilian governments signed the official agreement for the CBERS programme in Beijing. The agreement covered the development of two remote-sensing satellites, CBERS 1 and 2, with a development cost of US$100 million and a launch cost of US$50 million. China would share 70% of the total costs and Brazil would share 30%. The development would be carried out in four phases: Phase-B (concept definition), Phase-C (detailed design), Phase-D (satellite fabrication), and Phase-E (launch and operation). CAST and INPE would be the two main contractors for the satellite development.|
|1993 — CBERS development arrangement finalised. The CBERS 1/2 project made little progress in its early years, mainly due to a disagreement between the two partners over the location for assembling the second satellite. This detail was deliberately omitted in the original agreement to ensure that the agreement would be approved by the Brazilian Congress. This omission later resulted in a series of debates between the two sides. Finally, in 1993 the Chinese foreign minister Qian Qichen struck a deal during his official visit to Brazil. The new agreement allowed Brazil to control the satellites from its own ground station and the second CBERS satellite to be assembled in Brazil, as long as the Brazilian partner bear the travel costs for Chinese engineers and equipment.|
|1999 October 14 — CBERS 1 launched. The satellite was launched from Taiyuan atop a CZ-4B launch vehicle.|
|2000 March 2 — CBERS 1 handed over for operational use.|
|2000 May — CBERS 1 wide-field imager failed. 177 days after the satellite was handed over for operational use, the Brazilian-made onboard wide-field imager failed, though other onboard devices continued functioning normally. The satellite remained operational for nearly 5 years.|
|2002 November — CBERS 3/4 agreement signed. The governments of China and Brazil decided to expand the initial agreement by including another two satellites of the same kind, CBERS 3 and 4, as the second generation of the Sino-Brazilian cooperation effort.|
|2003 October 21— CBERS 2 launched.|
|2004 February 12 — CBERS 2 handed over for operational use.|
|2004 — CBERS 2B project approved by China and Brazil. The satellite was to serve as a stopgap before CBERS 3 could be launched. CBERS 2B was similar in size to its two predecessors CBERS 1/2, but featured some improvements on its mission payload, including a high-resolution (HR) panchromatic camera (HRC) that replaced the IRMSS imager. The satellite was also equipped with a GPS receiver for high accuracy in orbit insertion. Integration and testing of CBERS 2B was carried out in INPE’s Integration and Testing Laboratory in São José dos Campos.|
|2004 July — CBERS 3/4 specifications finalised. CAST and INPE finally agreed on the specifications for the second-generation satellites.|
|2007 September 19 — CBERS 2B launched.|
|2009 January 15 — CBERS 2 operation ended.|
|2009 May 11 — CBERS 2B altitude control failed. The satellite lost its altitude control due to the loss of gyroscope and a solar sensor. After firing its backup control, the satellite was repositioned to 10 km below its operational orbit, which affected the quality of its HR camera imagery.|
|2010 May 12 — CBERS 2B lost. Ground control had lost contact with the satellite since 16 April and it was declared lost on 12 May.|
|2011 December 22 — Ziyuan 1-02C launch. The satellite was based on the CBERS 1/2 design, but developed as a Chinese only project with no Brazilian participation. The satellite was China’s first operational civilian remote-sensing satellite, specifically designed for the Chinese Ministry of Land and Resources (MLR). The onboard observation package included two high-resolution cameras (HRC) and an infrared multispectral scanner (IRMSS) camera. The panchromatic cameras had a spectral resolution of 2.36 m and a joint ground swath of 54 km. The IRMSS had a spectral resolution of 5 m / 10 m and ground swath 60 km. The HRCs feature a lower compression rate (4:1) in its downlink transmission than that of the CBERS-2B (8:1), which allowed producing Earth images with better qualities.|
|2013 December 9 — CBERS 3 launch failed. The satellite did not enter its intended orbit due to a malfunction of its CZ-4B launch vehicle.|
|2014 December 7 — CBERS 4 launched. The satellite was successfully placed into its orbit by a CZ-4B launch vehicle lifting off from the Taiyuan Satellite Launch Centre.|