China Earth Observation Systems
The PRC has been actively pursuing Earth observation space systems for more than twenty years. Two models of LEO recoverable Earth observation satellites are in use and a sun-synchronous meteorological satellite system has been tested. China also receives LANDSAT-5, Japanese JRS-1, French SPOT, European Union ERS 1 and 2, and Canadian remote-sensing satellite data.
The satellite meteorological system had established through the combination of self-development and technology introduction. At the very beginning we received and used foreign meteorological satellite data. Then we established the meteorological satellite data receiving system. The system provides effective services for weather forecast, and flood and water logging monitoring.
The FY-1A was equipped with two multispectral scanning radiometers with 5 frequency channels. The FY-1B was equipped with two multispectral scanning radiometers with 10 frequency channels. The attitude control of these two satellites is the three-axis stabilization and direction to earth. The FY-2 satellite was equipped with a multispectral scanning radiometer with 3 frequency channels. It uses the double spin stabilization control system.
The satellite resources system, just like the satellite meteorological system, had played effective role in resources exploration, environment monitor, land management and planning, land use and survey, crops, yield estimation, geological prospecting and serious disaster estimation, etc..
In 1975 China successfully launched and recovered its first recoverable remote-sensing satellite. Then China became the 3rd country to have successfully developed satellite recoverable technology after the U.S and the former Soviet Union. Now China has already launched 17 recoverable remote sensing satellites into orbit.
In 1985 and 1986, China respectively launched two land survey satellites which obtained large number of remote-sensed pictures and achieved good results in application. This marks that China can use space remote sensing technology to serve the land management and construction of national economy. The CBERS was successfully launched on October 14,1999, which indicates that the development of our remote sensing satellites has reached a new level.
In 1988 and 1990 China launched its first generation of experimental polar orbit meteorological satellites, the FY-1A and FY-1B, which provided valuable experiences for the development and operation of the next generation meteorological satellites. In 1997 China successfully launched the FY-2 geostationary orbit meteorological satellite. The function of our meteorological satellite has approached the world level of the early 1990s.
On May 10, 1999, China launched the SJ-5 satellite successfully, indicating that China has reached the advanced world level in small satellite technology. In addition, China has laid certain foundation in the key technology necessary for the development of the oceanic observation satellite system.
China established radiometric calibration sites for remote sensing satellites in 1998. These calibration sites are open to international meteorological satellite operators and will make potential contributions to future polar-orbiting observation system.
Dun-Huang calibration site is for absolute radiometric calibration for visible, near IR and short wave IR band. It is located in the southwest of Gan Su Province (to the west of Dun Huang City), 40.1?, 94.3?. The size of calibration field is 30km×40km.
Qing Hai Lake site is for absolute radiometric calibration for thermal IR band and the absolute radiometric calibration of low reflectance target in visible and near IR band. It is located in the northeast of Qing Hai Lake of Qing Hai Province, 37?, 100?. The size is 4685 km2.
Simultaneous observation at/over the two sites in 1999 and 2000 were finished. The results are used in FY satellite data.
