|Country:||People's Republic of China|
|Operator:||Chinese Academy of Sciences|
|Begin:||November 5, 2021, 02:19 UTC|
|Starting place:||Taiyuan Cosmodrome|
|Launcher:||Long March 6|
|Status:||in orbit, active|
|Orbital time :||94.8 min|
|Track height:||515 km|
|Orbit inclination :||97.5 °|
|At the:||November 11, 2021|
Guangmu ( Chinese 廣 目 地球 科學 衛星 / 广 目 地球 科学 卫星, Pinyin Guǎngmù Dìqiú Kēxué Wèixīng ), also known as Sustainable Development Science Satellite 1 (可持续 发展 科学 卫星 1 号) or Sustainable Development Goals Satellite 1 (可持续 发展 目标一号 卫星) or SDGSAT-1 , is a geoscientific earth observation satellite of the Chinese Academy of Sciences manufactured by the Innovation Academy for Microsatellites . The satellite's operating orbit is a sun-synchronous orbit at an altitude of 500–510 km; its orbit crosses the equator at 9:30 a.m. local time from north to south.
The term “sustainable development strategies” was coined in April 1987 by the then United Nations Commission on Environment and Development . On 25 September 2015 were from the United Nations General Assembly on the World Summit on Sustainable Development adopted 17 targets for sustainable development - the so-called " Agenda 2030 for sustainable development " - including a termination of poverty and sustainable consumption and production patterns. One of the problems in devising concrete ways to achieve these goals has been a lack of quantized data. As a result, a good hundred members of the Chinese Academy of Sciences began in February 2018 under the direction of Guo Huadong (郭华东, * 1950), from September 2012 to November 2015 director of the Academy's Institute for Remote Sensing and Digital Geosciences , which also operates the Gaofen satellites supervised, with the development of a concept for a satellite that could deliver this data. They received technical support from the Innovation Academy for Microsatellites in Shanghai , also an institution of the Chinese Academy of Sciences.
The feasibility study was completed in December 2018; the project was officially approved by the Academy of Sciences. From January to April 2019, the specific designs for the satellite were then worked out. From April 2019 to June 2020, the Innovation Academy for Microsatellites built and extensively tested a first prototype. Then work began on building the actual satellite intended for use.
After three years of development, on November 5, 2021 at 02:19 a.m. UTC , the satellite was brought into a sun-synchronous orbit of about 515 km from the Taiyuan Cosmodrome with a Long March 6 launch vehicle . This happened on the occasion of the 50th anniversary of China's admission to the United Nations on October 25, 1971, and data from the entire earth are also collected. However, due to its sun-synchronous orbit, the satellite is always over the same areas at the same time of day, so that with its specialized instruments it can above all observe the economic development and the problems caused by it on the Chinese east coast, especially the Yangtze River Delta around Shanghai and the Pearl River Delta Canton and the Jing-Jin-Ji metropolitan area around Beijing and Tianjin , as well as the Maritime Silk Road . Secondly, data on cities with a population of more than one million inhabitants in the interior of the partner countries will be collected as part of the New Silk Road .
However, the scientists are particularly interested in the regional differences in economic development within China. The Heihe-Tengchong line defined by the population geographer Hu Huanyong (胡 焕 庸, 1901–1998) in 1935, also known as the "Hu line" in his honor, still exists today in almost unchanged form as a geo-demographic demarcation line. To the west of the line, 6% of the total population live on 57% of the land area, and 94% of the population to the east of it on 43% of the area. With Guangmu, the degree of urbanization in the different parts of the country is to be determined according to uniform criteria, from the distribution of large and small towns to the functionally delimited areas in the vicinity of a core city .
Guangmu - the name of the satellite is derived from the Chinese name of Lokapāla Virūpākṣa (广 目 天王, "All-observing King of Heaven") - is part of the geoscientific mass data project of the Chinese Academy of Sciences (地球 大 数据 科学工程 or CASEarth ). This five-year project, led by Guo Huadong and coinciding with the 13th legislative period of the National People's Congress , aims to merge the data from various systems ( CHEOS , Yaogan, etc.) and make them available to the scientific community in a cloud .
On September 22, 2020, President Xi Jinping announced the establishment of an international mass data research center for sustainable development in a speech at the United Nations General Assembly. Attracted was completed the establishment of the International Research Center of Big Data for Sustainable Development Goals (可持续发展大数据国际研究中心) a year later, on September 6, 2021. The usually "CBAS" abbreviated device ( " C enter of B ig Data for the 2030 A genda for S ustainable Development ") is located under the roof of the Institute of remote sensing and digital Earth sciences, Chinese Academy of sciences. The head office is in the Haidian district of Beijing, and the director of the research center, which is actually staffed internationally, is Guo Donghua. To document the entire earth with its swath width of 300 km, Guangmu needs 11 days. This is not sufficient, particularly with regard to monitoring the water quality with the multispectral camera. The CBAS had already started concept studies for further satellites in November 2021.
Guangmu is not based on a standard satellite bus , but is specially made by the Innovation Academy for Microsatellites in order to be able to derive the maximum benefit from the on-board instruments. Solar modules, for example, can heat up to 90 ° C if they are optimally aligned with the sun, which would severely impair the functions of the infrared camera. Therefore, Guangmu was equipped with only one solar cell wing and the infrared camera was protected with a screen on the side facing the solar modules. On the side of the satellite housing facing away from the sun, a large white radiator panel was installed, through which the heat generated can be radiated into space. In conjunction with an on-board refrigeration machine , it was possible to keep the working temperature of the infrared camera at −220 ° C. On the side of the housing opposite the solar cell wing there is a shielding plate that is unfolded after take-off and protects the other two cameras, which are arranged in the direction of flight in front of the infrared camera and use common optics, from scattered light reflected from the earth's atmosphere.
The three-axis stabilized satellite uses an inertial navigation system with an extended Kalman filter and two star sensors to orient itself via its position in space. This means that the housing can be aligned with an accuracy of 0.08 °, the stability is 0.0012 ° / s. The average power consumption of the satellite for payloads and operating systems is 576 W and can reach a peak of 1086 W. The transmission of the payload data to the ground stations of the Institute for Remote Sensing and Digital Geosciences takes place in parallel on two frequencies in the X-band , in regular operation with a data transmission rate of 810 Mbit / s and phase shift keying , in special cases with 540 Mbit / s and quadrature phase shift keying . This is at the limit of what the ground stations can handle. During normal operations, the stations in Miyun , Sanya and Kashgar are responsible for Guangmu . If there is not enough time to receive all data (up to 8 TB per day), the ground station in Kiruna , Sweden is also used. The satellite is controlled via the S-band.
The satellite, which weighs 753 kg including fuel, is equipped with three cameras, all of which have a swath width of 300 km:
Night vision camera
The earth observation satellites launched in China primarily serve the economic development of the country with the mapping of land resources, weather observation, etc. Guangmu is supposed to provide scientific data on the interaction between humans and the environment. A well-suited dimension for assessing human activity is lamplight. While the usual observation satellites take pictures mostly in daylight, Guangmu can use his from Changchun Institute of Optics, Fine Mechanics and Physics developed night vision camera with a resolution of 10 m ( panchromatic ) and 40 m (in color) the generation of light on the main and side streets of cities and communities as well as the lamplight in individual residential areas. Due to the relatively broad spectrum of 430–900 nm, the camera can differentiate between light from light bulbs, fluorescent tubes , mercury vapor lamps , LED lamps and other light sources. The word length for the quantization is 12 bits . With its dynamic range of 1: 1000 (about that of a compact camera ), the sensor of the night vision camera can take clear pictures even in the polar night, using only the moonlight reflected from snow and ice, and thus provide indices for human settlement patterns and economic activities for the entire globe deliver.
The camera for thermal infrared radiation was developed by the Shanghai Institute for Technical Physics of the Chinese Academy of Sciences (上海 技术 物理 研究所), it has a spatial resolution of 30 m. The camera is equipped with an integrated infrared filter and works in the three spectral bands 8 -10.5 µm, 10.3-11.3 µm, and 11.5-12.5 µm. The temperature resolution is 0.5 ° C, it can clearly depict objects on the earth's surface in a temperature range of −50 ° C to +70 ° C. The word length for the quantization is also 12 bits here. The aim of this camera is to examine, among other things, the temperature differences between historic old towns and new development areas.
More than half of the world's population lives in an approximately 200 km wide strip along the coast of the sea. Therefore, with his multispectral camera developed by the Institute for Information Acquisition through Aerospace of the Chinese Academy of Sciences, Guangmu observes the water quality of the coastal and inland waters in seven frequency bands. In the spectra used by the camera, outbreaks of green algae , cyanobacteria and red tide can be precisely measured and warnings of a change in the water quality can be issued. The multispectral camera has a resolution of 10 m.
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