EARTH RESOURCES: HUANJING

Eight years after the start of Zi Yuan, China introduced a new, more specialized program of Earth resources satellites, focused on the environment and disaster­warning. Called “Huanjing” in Chinese, meaning “environment”, two were launched together from Taiyuan on 7th September 2008 into a high-inchnation, Sun-synchronous orbit. The program was geared to the 74-nation intergovernmental Group on Earth Observations (GEO), 2005, led by China and the United States under the International Charter for Space and Major Disasters, 2000, intended to coordinate the supply of images to disaster-struck regions. China stated that one of its purposes was to follow land-use development, especially illegal land use by profiteers.

These were small satellites, both 475 kg and based on the standard design or bus called CAST968 (China Academy of Space Technology, 1996, “8” for the month or design number). The theory behind the “bus” idea was to develop a standardized design which could be adapted for a variety of missions, standardization lowering the cost of production. They carried four cameras: two CCD imagers of 30-m resolution and a swath of 700 km; an ultraviolet camera of 100-m resolution and a swath of 50 km; a super-spectral imager (A only); and an infrared camera of 150-m resolution and a swath of 750 km (B only). The satelhtes had a revisit orbit of four days, a crossing time of 10:30 each day, and a service life of three to five years. They were aimed at circular orbits of 649 km at 98°, similar to the Yaogan (below), but lower than the maritime observation satellite, Haiyang, at 798 km (below). Data transmission rates were 120 МВ/sec (A) and 60 МВ/sec (B). Data were sent to the China Resource Satellite Application Centre, completed in 2008, which also handled CBERS.

First images were received on 9th September 2008 and the satellites were declared operational on 20th March 2009. Within a year, 510,000 images had been provided for the Ministry of Environmental Protection and a further 70,000 for other registered users. In the area of disaster relief, the satellites provided imaging that was used for two great snows (Tibet and the north), earthquakes (e. g. Wenchuan), forest fires (Australia), a mud slide (Chongqing Wulong), river flood (river Huai, Yellow River), and frozen seas (e. g. Bohai). The photographs were especially useful in identifying transport routes whereby rehef can be provided. The Huanjings also followed algal blooms, water sediment levels in rivers, risks of water contamination, sand storms, air pollution, straw-burning, and oil spills, both for environmental protection and subsequent law enforcement. Earthquake images from satellites were able to pick out collapsed buildings (red) and intact ones (green). They played an important role in mapping landslides, glacial lakes, and the Bohai Sea ice disaster of winter 2009-10. Both satelhtes were used by CEODE to give assistance to Australia during the bush fires in Victoria, Australia, in February 2009, being repositioned to fly over the disaster areas twice a day. The Huanjings beamed down 130 GB of data over the following three weeks in optical and infrared, following the intensity and direction of the fire fronts, both to assist the fire fighters and to enable residential communities to be evacuated in time. The Huanjing program has been well documented, certainly in comparison to Zi Yuan [13].

They will be followed by Huanjing 2, which will carry a microwave radiometer, microwave scatterometer, and radar altimeter. Before them, the radar will be tested by Huanjing 1C, which was first exhibited at the Zhuhai air show in 2009. Huanjing 1C is a larger 890-kg radar satellite, with 5-m resolution and a swath of 400 km, able to make four-day revisits. Ultimately, according to the Academy of Sciences’ long-term plan for space development, Roadmap 2050, China’s objective is to build data on climate changes across up to 20 parameters (e. g. methane, ice and

Fires in Australia, taken from Huanjing. Courtesy: CEODE.

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Straw-burning detected by Huanjing. Courtesy: COSPAR China.

Map of earthquake zone, collapsed buildings, taken from Huanjing. Courtesy: COSPAR China.

Huanjing 1C will carry this type of radar system. Courtesy: COSPAR China.

snow coverage, aerosols, nitrogen oxides, land use, cloud and precipitation, forestry) so as to construct a reference model of climate systems and climate change. This will be fed by next-generation three-dimensional microwave sensing technology to measure the oceans, salinity, rain, vegetation, and the main features of land masses. The data will be stored in what is called the Digital Earth Scientific Platform, which comprises:

• a central node, called the Dawn supercomputer;

• three network nodes (Miyun (Chinese landmass), Kashi (western Asia), and Sanya (South China sea to Mekong);

• ground stations in Xian, Changchun, Shanghai, Sanya, Kunming, Lhasa, Kashi, and Urumqi;

• overseas stations in Brazil and the Zhongshan base at the South Pole;

• 18 sub-nodes, the intention being to update data through the system daily.

The series is summarized in Table 6.5.

Table 6.5. Huanjing series.

Huanjing 1A 7 Sep 2008

Huanjing IB

CZ-2C from Taiyuan.