China High-resolution Earth Observation System (CHEOS)
In order to improve the comprehensive capabilities of China's earth observation system, in 2010, the Chinese government approved to implement CHEOS. China had developed Fengyun, Haiyang, Ziyuan satellite series & a constellation (composited by small satellites). These satellites has made great contributions in weather forecasting, climate variation and ocean monitoring, environment and disaster monitoring and forecasting etc. The space-based system consists of 7 optical/microwave satellites.
The civilian HDEOS (High-Definition Earth Observation Satellite) program was proposed in 2006, it received government approval and was initiated in 2010. China planned to launch six HDEOS spacecraft between 2013 and 2016. The main goal of the HDEOS series was to provide NRT (Near-Real-Time) observations for disaster prevention and relief, climate change monitoring, geographical mapping, environment and resource surveying, as well as for precision agriculture support. The major users of the observation data will be the Ministry of Land and Resources, Ministry of Environmental Protection, and the Ministry of Agriculture.
In 2010, the Chinese government approved to implement CHEOS (China High-resolution Earth Observation System), which is an extension of the HDEOS program. The CHEOS series would consist of seven optical/microwave satellites. EOSDC-CNSA (Earth Observation System and Data Center - China National Space Administration) is responsible for organizing the construction of the CHEOS program. The CHEOS program comprises the elements of the spaceborne system, the near-space system, aerial system, the ground system and application system as a whole to realize Earth observation at high temporal, spatial and spectral resolution. The constellation may be utilised in Chinese president Xi Jinping’s ‘One belt one road’ regional development project.
By following an arrangement of integral observation from space, air and ground, the CHEOS develops space-based system, nearspace system, aerial system, ground system and application system as a whole to materialize earth observation at high temporal, spatial and spectral resolution, which is now in smooth progress. Overall, to meet the strategic demands of the national economic development and social progress.
Gaofen-1 / 6
Since the inception of the Gaofen project in 2013, China had an increasingly clear view of the planet. Launched in April 2013, Gaofen-1 (gao fen = high resolution) can cover the globe in just four days. On 26 April 2013 the first satellite of CHEOS was successfully launched by LM-2D, which marked that CHEOS had entered into a new stage with features "contructing, operating, applying". This launching has also carried 3 microsatellites which is made by Ecuador, Argentina, Turkey. Gaofen-1 is based on the CAST small satellite bus designed and developed by the China SpaceSat Co. Ltd. of Beijing (also referred to as DFH Satellite Co. Ltd.), the commercial subsidiary of CAST (Chinese Academy of Space Technology). F-1 employs the CAST-2000 bus, it is configured with two 2 m Pan/8 m MS camera and a four 16 m MS medium-resolution and wide-field camera set. GF-1 realizes an integration of imaging capacity at medium and high spatial resolution and with a wide swath, the design life is 5 years with a goal of 8 years.
The launch of a second satellite of this type, GF 6, was planned for 2017, and will include a two meter resolution pan-chromatic camera, an eight meter resolution multi-spectral camera and a 16 meter resolution wide-angle multi-spectral camera.
A Long March-11 carrier rocket lifted off at noon on 30 April 2022 off the coast of the East China Sea, successfully sending five Jilin-1 Gaofen satellites into preset orbits, marking the first time that China has realized a "one-stop" launch mode in near sea.
Gaofen-2, employs the CS-L3000A bus, it is configured with one 1 m Pan/4 m MS camera, the design life is greater than 5 years. sent into space on 19 August 2014, with a resolution of 0.8 meters in full color and can collect multispectral images of objects 3.2 meters or longer in length. GF-2 was launched on a Long March-4B vehicle from TSLC (Taiyuan Satellite Launch Center), China.
China's solid-fueled KuaiZhou-1A (KZ-1A) Y11 carrier rocket blasted off at 11:40 am on 13 November 2019 and successfully sent the Jilin-1 Gaofen 02A satellite into planned orbit from the Jiuquan Satellite Launch Center in Northwest China's Gansu Province. The Jilin-1 Gaofen 02A satellite is a high-resolution optical satellite independently developed by Chang Guang Satellite Technology Co. Ltd. After entering the planned orbit, the Jilin-1 constellation will have 14 satellites in the orbit, which helps provide timely remote sensing information services in many fields, including agricultural and forestry production, environmental monitoring and smart city.
China sent a new optical remote sensing satellite into space from the Taiyuan Satellite Launch Center in northern China's Shanxi Province at 10:55 a.m. (Beijing Time) 07 December 2019. The Jilin-1 Gaofen 02B satellite, which belongs to the Jilin-1 satellite family, was launched by Kuaizhou-1A (KZ-1A) and entered the planned orbit successfully. The satellite was independently developed by the Chang Guang Satellite Technology Co., Ltd., featuring high resolution, wide width and high-speed data transmission. The satellite will form a network with the 14 previously launched Jilin-1 satellites, providing remote sensing data and services for agriculture, forestry, resources and environment. KZ-1A is a low-cost solid-fuel carrier rocket with high reliability and a short preparation period. The rocket, developed by a company under the China Aerospace Science and Industry Corporation, is mainly used to launch low-orbit microsatellites.
China's optical remote-sensing satellite Jilin-1 Gaofen 02C failed to enter the preset orbit on 12 September 2020. The satellite was launched aboard the Kuaizhou-1A carrier rocket from Jiuquan Satellite Launch Center at 1:02 pm. The launch center said the mission failed because abnormal performance was identified. Specific reasons of the failure were under further investigation.
The Gaofen-3 employs CS-L3000B bus, configured with multi-polarized Cband SAR at meter-level resolution, with designed lifespan of 8 years. Along with the Long March 4C rocket GF-3 was developed by the China Academy of Space Technology and the Shanghai Academy of Spaceflight Technology, under guidance of the China Aerospace Science and Technology Corporation. China launched a new high-resolution Synthetic Aperture Radar (SAR) imaging satellite from the Taiyuan Satellite Launch Center in northern Shanxi Province on 10 August 2016. The Gaofen-3 satellite was launched off on the back of a Long March 4C rocket at 6:55 am Beijing time, according to the center. It was the 233rd flight mission by a Long March carrier rocket. As China's first SAR imaging satellite that has a reslution of one meter, it covers the globe with an all-weather, 24-hour observation service and will be used for disaster warning, weather forecasting, water resource assessments, and the protection of maritime rights. With 12 imaging modes, the high-definition observation satellite is capable of taking wide pictures of earth and photographing detailed scenarios of specific areas. Gaofen-3 is China's first low orbit remote sensing satellite that has a lifespan of eight years. It is able to provide high-definition remote sensing data for its users over long periods of time.
As China's first SAR imaging satellite that is accurate to one meter in resolution, it covers the globe with an all-weather, 24-hour observation service and will be used for disaster warning, weather forecasting, water resource assessments, and the protection of maritime rights. Compared with optical imaging satellites, Gaofen-3 will better perform disaster monitoring as the SAR imaging satellite is capable of imaging in severe weather conditions as it uses microwave transmission. "The launch of Gaofen-3 is expected to reduce dependence on data provided by foreign microwave imaging satellites," said Jiang Xingwei, deputy chief engineer of Gaofen satellite application system.
Gaofen-4, employs GEO remote sensing bus, configured with a 50m staring camera, operating on the geo-synchronous orbit. GF-4 can provide an imaging area of 7000km×7000km with individual scene covering an area of 400km×400km, and with capacity for high temporal resolution remote sensing monitor at minute-level. GF-4 is designed for 8 years life. Launched in late 2015, GF-4 was China's first geosynchronous orbit high-definition optical imaging satellite and claimed to be "the world's most sophisticated". The satellite can cover more than 26 million sq km including 8.5 million sq km in China and 17.7 million sq km overseas, with an optical spatial resolution of better than 50 metres as well as infrared sensing capabilities. The 4,600kg satellite is part of the China High-resolution Earth Observation System (CHEOS) which, according to the China National Space Administration (CNSA), aims to provide China with all-weather, all-day and global Earth observation coverage by 2020.
According to China Daily, in mid-March 2016 Gaofen-4 began to take pictures for its major users such as the Ministry of Civil Affairs, State Forestry Administration, China Earthquake Administration and China Meteorological Administration to help with disaster prevention and relief, forest monitoring as well as weather forecast.
According to Gaofen-4 chief designer Li Guo, the new satellite is able to "see" an oil tanker with its huge camera, attaining the best imaging capability amongst the world's high-orbit remote-sensing satellites. The newly-launched satellite is equipped with several visible light and infrared cameras, which cover an area of about 7,000 by 7,000 kilometers (4,350 miles) that includes China and its surrounding regions. Gaofen-1 was launched in April 2013 and entered an orbit of 600 kilometers (373 miles) away from the Earth. The Gaofen program is expected to put seven HD observation satellites into orbit by 2020.
GF-5 employs the SAST-5000B bus [SAST = Shanghai Academy of Spaceflight Technology], configured with six payloads, including a VIS and SWIR (Shortwave Infrared) hyperspectral camera, spectral imager, greenhouse gas detector, atmospheric environment infrared detector at very high spectral resolution, differential absorption spectrometer for atmospheric trace gas, and a multi-angle polarization detector. GF-5 has a design life of 8 years and was scheduled to launch in 2016.
On 10 May 2018 China launched Gaofen-5, the world's first hyper-spectral satellite, to monitor air and land, a move that would give China a more comprehensive insight into the atmospheric environment, an expert said. The Gaofen-5 was launched at the Taiyuan Satellite Launch Center via a Long March 4C carrier rocket.
The satellite, developed by the China Aerospace Science and Technology Corporation, is China's first hyper-spectral imaging satellite that can monitor air and water pollution, survey geological resources and analyze climate changes, according to an official statement from the company website. The successful launch of Gaofen-5 will also free China from depending on foreign hyper-spectral remote sensing data, the statement said.
The Gaofen-5, with a designed lifespan of eight years, is equipped with six state-of-the-art observation payloads that would provide the most comprehensive observation data compared to other Chinese remote sensing satellites, Li Zhengqiang, an expert at the Chinese Academy of Sciences' Institute of Remote Sensing and Digital Earth, told the Global Times.
"The observation capabilities of previous Chinese environmental observation satellites were not as comprehensive as the Gaofen-5's. The Gaofen-5 has more sensors, especially those monitoring the air," Li said, who is enthusiastic about Gaofen-5's potential to monitor greenhouse gases, contaminated gases and harmful particles that cause smog. "Gaofen-5 proves the technology has matured. Loaded with multiple hyper-spectral sensors, the technology can now monitor the atmosphere, water and Earth's surface," Li said.
China will launch its follow-up model, the Gaofen-6, later in 2018 to form a network with other Gaofen satellites, the Xinhua News Agency reported 10 May 2018. Data gathered by Gaofen satellites are being widely used in more than 20 fields and 30 provinces, China News Service reported. It also contributes to international cooperation by laying the foundation to the Belt and Road initiative's space and information programs, according to the report.
Gaofen-7 was launched 03 November 2019 on a Long March-4B rocket at 11:22 a.m. (Beijing Time) from the Taiyuan Satellite Launch Center in north China's Shanxi Province. Gaofen-7 has achieved a breakthrough in sub-meter level 3D mapping camera technology, meeting the highest mapping accuracy requirement among the Gaofen series Earth observation satellites Hyperspectral sensors providing hyperspectral imaging can be beneficially applied in a wide array of practical applications. Examples of such uses include aid in the detection of chemical or biological weapons, bomb damage assessment of underground structures, drug production and cultivation, as well as the detection of friend or foe troops and vehicles beneath foliage or camouflage.
Hyperspectral sensors collect image data across dozens if not hundreds of spectral bands, combining the technology of spectroscopy and remote imaging. The measurements captured by hyperspectral sensors make it possible to derive a contiguous spectrum for each image pixel. In other words for each x, y coordinate of an image (i.e., a pixel), rather than a single value for a gray or visible color, there is a third dimension--a vector, providing distinct information for that particular pixel across the large spectrum of wavelengths.
A black-and-white photograph of an object or a geographic area is a two dimensional construct of the actual image or area--for each x, y coordinate in the image there is a single value blackness or whiteness of that particular image spot. As human beings, the eye can perceive useful information about objects or areas based on the differences between black, white, and the shades of gray. Color photographs add more visual information, but for most purposes the color information that is represented is tied to the visual spectrum. For each x, y coordinate in the image there is an approximation of the visual color spectrum of that particular image spot created through the blending of three color values, such as for example Red, Green, and Blue.
Multi-spectral sensing systems such as the Landsat Thematic Mapper remote imager and weather satellites produce images with a few relatively broad wavelength bands. The imager may capture a visual spectrum image and also one in infrared, but still they are limited in their ability to perceive information that may otherwise be present in a different part of the spectrum. As different materials reflect wavelengths of visible and invisible light selectively, analysis of the contiguous wavelength spectrum permits finer resolution and greater perception of information contained in the image, through separation and evaluation of different wavelengths. For example, inorganic materials such as minerals, chemical compositions and crystalline structures control the shape of a representative spectral curve and the presence and positions of specific absorption bands.
Some targets are relatively easy to detect using standard techniques; whereas, other may not be. For example, detection of a terrain, such as asphalt, or concrete may be relatively straightforward for some images in which pixels (ground resolution cells) are filled by substantially the same material (e.g., asphalt or concrete). Alternatively, the measured signatures of a dispersed target, such as a gaseous plume, are complicated by a combination of phenomenology including effects of the atmosphere, spectral characteristics of the background material under the plume, temperature contrast between the gas and the surface, and the concentration of the gas. All of these quantities vary spatially further complicating the detection problem. For example, an effluent target in a low wind and having a relatively dense and very bright target signature on at least a few contiguous pixels may be relatively easy to detect, even with a substantially high threshold. Accordingly, such relatively easy to detect targets would require minimal or no spatial processing. Alternatively, targets in a high wind and/or sparse, or weak may be present in dozens to hundreds pixels of a given image. Unfortunately, all or most such pixels may be below conventional thresholds.
Gaofen-8 / 9
Originally, Gaofen was projected as a program comprised of seven satellites, but 2015 saw the launches of Gaofen-8 and 9 – probably additions to the original constellation in a suspected merger of military and civilian programs. The two additional satellites probably originate from the Yaogan military reconnaissance satellite series. The Gaofen satellites are likely employed as needed for civilian and military purposes – matching the capabilities of Yaogan in terms of ground resolution.
China made a surprise launch on 26 June 2015, using a Long March 4B rocket to lift the Gaofen-8 Earth observation satellite into Low Earth Orbit. The launch took place at the Taiyuan Satellite Launch Center in Shanxi province at 14:22 Beijing time (6:22 UTC). Chinese language media report that Gaofen-8 was developed by the China Aerospace Science and Technology Corporation (CASC) and will be used in such areas as land surveying, urban planning, road network design, estimating crop yields, as well as disaster preparedness and reduction. Despite its denomination, Gaofen-8 was only the third launch in a series of what will be eight or nine satellites in the China High-resolution Earth Observation System (CHEOS). The launch was the 205th of China’s Long March rocket series, lifting Gaofen-8 into a 469 x 481 km orbit with an inclination of 97.3 degrees.
China on 14 September 2015 quietly launched the Gaofen-9 high-resolution Earth observation satellite on a Long March 2D rocket from the Jiuquan satellite launch centre in the Gobi desert. The launch went ahead at 12:42 Beijing time (04:42 UTC) with the only warning coming from a prior airspace notification. The successful launch was confirmed by state-run CCTV. Gaofen-9 was the fourth to be launched from what is expected to be eight or nine satellites forming the China High-resolution Earth Observation System (CHEOS). Chinese state media reported it would be used to provide sub-meter resolution optical images for use in land surveying, urban planning, land ownership, road network design, estimating crop yields, as well as disaster preparedness and reduction.
China has received images from a pair of 0.5-meter high-resolution remote sensing satellites launched in late December 2016, the China Aerospace Science and Technology Corporation (CASC) said 11 January 2017. Tourists were seen visiting the Potala Palace in Tibet Autonomous Region in the captured images.
The satellites, SuperView-1 01/02, on the back of a Long March 2D rocket lifted off from the Taiyuan Satellite Launch Center in Shanxi Province. The two are operating at an altitude of 500 kilometers, with a panchromatic resolution of 0.5 meters and multispectral resolution of two meters, said Zhang Xiaomin, vice general manager of the Dongfanghong Satellite Co., Ltd under the CASC. The China Siwei Surveying and Mapping Technology Co. Ltd, which is also under the CASC, is in charge of commercial operation of the satellites. Xu Wen, general manager of China Siwei, said the satellites will provide services in a number of fields from environmental monitoring to disaster mitigation.
SuperView-1 constellation includes 2 satellites and provides imagery with 0.5 meter panchromatic resolution and 2 meter multispectral resolution. The swath width is 12 km and the descending node time is 10:30 am. It possesses high agility and runs with multiple collection modes including long strip, multiple strips collect, multiple point targets collect and stereo imaging. The maximum single scene can be 60 km * 70 km. And in the middle of 2017, another two 0.5 m resolution satellites will be launched to the same orbit. From then, there will be four 0.5 m resolution satellites and phased 90° from each other on the same orbit to collect imagery for the clients across the world.
Located in Beijing, Space View is a leading provider of EO satellite data and geospatial information services in China. The company business covers optical and SAR satellite imagery, data processing, value-added products, solutions, software and GIS platform. As the operator of SuperView from space to ground, not only does Space View manage the imaging services, but also promotes construction of direct-receiving and virtual stations around the world. Space View is working on worldwide network to distribute Chinese EO satellite imagery in global market networking.
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