ZiYuan-1 (CBERS) Earth Remote Sensing Satellite

Last updated: 25 September 2007

ZY-1 (ZiYuan-1), also known as China-Brazil Earth Resources Satellite (CBERS), is an Earth remote sensing satellite jointly developed by China and Brazil. Equipped with CCD cameras and IR scanner, the satellite is used for ground survey, natural disaster monitoring, agriculture and forest monitoring, etc. A total of two satellites (No.1 and No.2) have been launched since 1999, with the third (No.02B) scheduled to be launched in 2007. The two countries have also signed the agreement to develop an additional two satellites (No.03 and No.04) in the next few years.

China and Brazil have been discussing a possible co-operation in developing an Earth resource remote sensing satellite since 1986. An formal agreement was signed between INP and China Space Agency on 6 July 1988 on two Earth-imaging satellites to be launched by China’s CZ-4B launch vehicle. The satellite’s Chinese name is ZiYuan-1 (ZiYuan = “Resource”). China contributes approximately 70% of the programme costs. The programme initially called for two launches in 1996 and 1998~1999, but this was substantially delayed due to financial reasons.

The first satellite ZY-1 No.1 (CBERS-1) was launched on 14 October 1999 by a CZ-4B launch vehicle from Taiyuan Satellite Launch Centre (TSLC). The satellite is operated on a time shared basis by the two countries. After the launch until March 2001 INPE performed only TM monitoring, orbit determination and payload operations. Thereafter, during the next six months, the overall satellite control was assumed by INPE. During this period, (ended on September 2001, when the overall CBERS-1 control returned to China responsibility) INPE has performed two orbit manoeuvres to correct the time evolution of the orbit longitude phase drift.

The satellite is mainly used to monitor land resource changes of China and Brazil, renewing the two countries' national land use map every year. Data acquired by CBERS-1 can be used to measure cultivated area, estimate forest volume and observe crops growing way and output and the carrying capacity of the steppe as well as their annual changes. In natural disaster monitoring missions, it can be used for rapid investigation of flood, water logging, forest fire, earthquake and wind-blown sands. In some special cases, these data could also be used for military purpose.

The ZY-1 No.1 (CBERS-1) had operated in orbit for nearly four years, which is almost twice of its designed life span. For the first three years period, China had received 310,000 pictures of various data from the satellite in accumulation and domestic customers purchased over 10,000 pictures. This satellite was replaced by a second satellite ZY-1 No.2 (CBERS-2) launched on 21 October 2003 from TSLC by a CZ-4B launch vehicle.

In October 2004, the director of the China Space Agency, SUN Laiyan, announced that in the next few years the two countries have agreed to develop an additional three satellites ZY-1 No.2B (CBERS-2B), ZY-1 No.3 (CBERS-3), and ZY-1 No.4 (CBERS-4). The future satellites will still be based on the ZY-1 bus platform design but with improved cameras for higher resolutions and better performance. The ZY-1 No.02B was launched on 19 September 2007.

The 1,450kg ZY-1/CBERS satellite is box-shaped with a 985W capacity, a single solar wing consisting of 3 panels, and will operate in an 800 km sun-synchronous orbit with a 5-day or 26-day repeating ground track pattern.

The Earth observation payload includes three primary sensors (the first two of Chinese origin):

• CCD Camera: Five bands (0.51-0.73 µm, 0.45-0.52 µm, 0.52-0.59 µm, 0.63-0.69, µm, and 0.77-0.89.µm); 20-m resolution; 113 km swath;
• IR Multi-Spectral Scanner: Four bands (0.50-1.10 µm, 1.55-1.75 µm, 2.08-2.35 µm,and 10.40-12.50 µm); 80-160-m resolution; 120-km swath;
• Wide-Field Imager: Two bands (0.63-0.69 µm and 0.76-0.90 µm); 260-m resolution; 900-km swath.

The satellite also carries a Data Collection System and a Space Environment Monitor.

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