Dong Fang Hong

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Dong Fang Hong (abbreviation DFH ; Chinese  東方 紅  /  东方 红 , Pinyin dōngfāng hóng  - "The East is red") describes a type of Chinese communication satellite . Satellites of this series were transported both into a low earth orbit and (from Dong Fang Hong 2-2) into a geostationary orbit. They served as test satellites ( Dong Fang Hong 1 ) and telecommunications.

history

When the Soviet Sputnik 1 satellite launched into space on October 4, 1957 , the Chinese leadership took note of this with great interest. Mao Zedong said in his famous speech on May 17, 1958 at the Second Session of the 8th Party Congress of the CCP (May 5-23, 1958) that “we will now also participate a little with the satellites” (我们 也 要搞一点 卫星). The Chinese Academy of Sciences was instructed to investigate the possibilities for a Chinese satellite in the strictest of secrecy. After Qian Xuesen and Zhao Jiuzhang had already spoken out in favor of building a satellite at the beginning of the year, the Academy gladly accepted the order: the development of a satellite was declared one of the most important projects of 1958 and was given the internal name " Project 581 " . At that time we were just about to make a “ big leap forward ”. The whole country was carried by a wave of euphoria that had nothing to do with economic realities. The Chinese leadership realized this relatively quickly, and on January 21, 1959, Zhang Jingfu , vice president of the academy, conveyed to the scientists an order from Deng Xiaoping (then general secretary of the CCP's Political Bureau ) to postpone the satellite project for the time being, as it was with economic strength of the country would not be compatible.

National People's Congress, first session of the third legislative period (December 21, 1964 - January 4, 1965)

When the National People's Congress met for the first session of the third legislative period on December 21, 1964 , Zhao Jiuzhang, who had just been elected to parliament for the Society of September 3 , took the opportunity to write to Prime Minister Zhou Enlai on December 27 and to propose again the development of a Chinese satellite. Shortly afterwards, on January 8, 1965, Qian Xuesen wrote a similar letter to the Defense Technology Commission of the People's Liberation Army . Commission chairman Nie Rongzhen and Prime Minister Zhou Enlai approved the plan of the scientists, which was given the name "Project 651" (651 工程, Pinyin 651 Gōngchéng ), so "The project started in January 1965". The development of the satellite was initially incumbent on the Seventh Ministry of Mechanical Engineering , which emerged from the 5th Research Institute of the Ministry of Defense on January 4, 1965 by resolution of the People's Congress, and the Project Planning Institute 651 of the Chinese Academy of Sciences , and then on February 20, 1968, which dealt with several space issues Institutes of the Academy of Sciences as well as some precision engineering factories formed the Chinese Academy for Space Technology , which, partly through subsidiaries, manufactures all the larger satellites and space probes of the People's Republic of China to this day.

In addition to the satellite itself began in the second half of 1965 based on the Dongfeng 2A , the first completely self-developed medium-range missile of the People's Republic of China, initially under the auspices of the eighth engineering , from 1968, the first Academy of the Seventh Ministry of Machine-building Industry , with the Work on a three-stage launcher, the Changzheng 1 , which should be able to bring the satellite into near-Earth orbit. After an initial false start on November 16, 1969, on April 24, 1970, China's first satellite, Dong Fang Hong 1 (东方 红, meaning “ The East is Red ”), was launched from the Jiuquan Cosmodrome into space.

So far launched satellites of the series

  • January 29, 1984 Dong Fang Hong 2-1 ( geostationary orbit not reached)
  • April 8, 1984 Dong Fang Hong 2-2
  • February 1, 1986 Dong Fang Hong 2-3
  • March 7, 1988 Dong Fang Hong 2A-1
  • December 22, 1988 Dong Fang Hong 2A-2
  • February 4, 1990 Dong Fang Hong 2A-3
  • December 28, 1991 Dong Fang Hong 2A-4 (false start)
  • November 30, 1994 Dong Fang Hong 3-1 (geostationary orbit not reached)
  • May 12, 1997 Dong Fang Hong 3-2

DFH-3 bus

In addition to the actual Dong-Fang-Hong satellites, the housing of the spacecraft with its drive system, the energy supply with accumulator as well as 3 fold-out solar panels on the right and left and the on-board computer, i.e. the so-called " satellite bus ", became the basis for the Beidou navigation satellites and the military communication satellites of the Fenghuo and Shentong series (神通, "Magical ability") are used. As part of the lunar program of the People's Republic of China , the DFH-3 bus, slightly modified and now under the name DFH-3A, the basis for the orbiters Chang'e-1 and Chang'e-2 . The relay satellites of the Tianlian series used from 2008 for communication with the manned Shenzhou spaceships are also based on the DFH-3A bus.

From 2008, the improved version DFH-3B was developed for the Beidou-2 system covering the Asia-Pacific region , which was later also used for the satellites of the global Beidou-3 system positioned in inclined geosynchronous orbit (IGSO) . This bus holds an orbit once it has been taken with a precision of ± 0.05 °, i.e. twice as accurate as the previous models DFH-3 and DFH-3A, where the precision is ± 0.1 °. In addition, the antennas of the DFH-3B-Bus remain aligned with a tolerance of 0.06 ° for the transverse axis and longitudinal axis and 0.2 ° for the yaw axis, more than twice as precisely as in the previous models. With up to 4 kW, this variant can provide significantly more power for the payloads and it also has a longer service life of 12-15 years.

DFH-4 bus

As the requirements for communication satellites increased steadily in the 1990s, the Chinese Academy of Space Technology began the theoretical preliminary planning for a next-generation satellite bus , which will be used for replacement satellites for Dong Fang Hong 3-1 and 3-2 as well as for cooperation projects with the Should be used abroad. In December 1999, the then Commission for Science, Technology and Industry for National Defense and the Ministry of Finance approved the company to begin with the specific development work, supported with funds from the 9th five-year plan (1996-2000). First of all, a few basic problems had to be solved, such as accommodating a large fuel tank and gas bottles for the cold gas rocket engines to stabilize the position - the platform was designed for a service life of 15 years - then the project was officially started in October 2001. At the time, it was thought that the satellite platform could be ready for production in 4 years.

In the end, however, it took a year longer until, on October 29, 2006, Sinosat 2, the first satellite based on the DFH-4 bus, could be launched from the Xichang cosmodrome . Sinosat 2 reached the planned orbit, but then the four-part solar panels did not unfold. Attempts to do this by manual control from Earth failed, the satellite's parabolic antennas could not be unfolded, and when the on-board battery ran out after a month, the 2 billion yuan (luckily insured) satellite was nothing but space junk . The proven DFH-3 bus was then used for the successor satellite Sinosat 3, which was launched on June 1, 2007.

The communication satellite NigComSat-1 , which was launched on May 14, 2007 on behalf of the National Space Research and Development Agency of Nigeria , had problems with the solar panels again after almost a year of satisfactory work. In April 2008, the drive of the southern solar module wing failed, so that it could no longer align itself with the sun and the power supply to the satellite was reduced by half. On November 11, 2008 at 04:33 Beijing time, the northern wing also failed and the $ 256 million satellite had to be maneuvered into a cemetery orbit as irreparable . In November 2008, the China Great Wall Industry Corporation (a subsidiary of the China Aerospace Science and Technology Corporation ), which had arranged the construction and launch of the satellite, promised Nigeria a generous settlement of claims . On March 24, 2009, a contract was signed with the operating company NIGCOMSAT for the provision of a free and technically identical replacement satellite (NigComSat-1R) - except for the solar module wings - which was finally launched on December 20, 2011. The Chinese Academy for Space Technology had already started to revise the solar panel system after the incident in April 2008.

For the communications satellite Venesat-1 , launched for Venezuela on October 29, 2008 , the changes came too late. Similar to NigComSat-1, there was initially a problem with the rotation mechanism of one of the solar cell wings in February 2020, and then also with the second at the beginning of March, so that the satellite was switched off on March 13, 2020, three and a half years before reaching its expected service life of 15 years had to become.

DFH-5 bus

In 2008, the Research Institute 510 of the Chinese Academy of Space Technology, which had been working on the technology since the 1970s - initially theoretically - began developing an electric drive for satellites. Here, two separate engines were tested: a Xenon - ion propulsion to convey the satellite into a higher orbit, and a Hall-effect thruster in order to lower the orbit of the satellite. The drive was initially installed in the Shijian 9A (实践 九号 卫星 a 星) test satellite and, after its launch on October 14, 2012, tested in orbit from December 2012. At the beginning there were problems with the ion drive, which were attributed to contamination of the xenon used as a support mass . After the contaminants were expelled, the ion thruster operated normally.

Initially, it was planned to use the electric drive on the DFH-4 bus. Then, however, with the DFH-5 bus under the direction of Zhou Zhicheng (周志成, * 1963), head of the communications satellite department (通信 卫星 事业 部) at the Chinese Academy of Space Technology, a completely new platform for large satellites Developed in geostationary orbit, with two six-part solar panels that, in addition to the power supply for the platform's operating systems, deliver 18 kW for the payload, with an innovative heat radiation system and improved control electronics. The DFH-5 bus was first used on July 2, 2017 as the base for the Shijian 18 experimental communications satellite, which crashed into the Indian Ocean six minutes after takeoff due to a problem with the turbo pump in an engine of the Changzheng-5 launch vehicle . The launch of the successor satellite Shijian 20 succeeded after a few delays on December 27, 2019 without any problems.

The current version of the DFH-5 bus has a hybrid drive. On the one hand, it has a liquid thruster that delivers a high vacuum thrust and is used to quickly bring the satellite into its orbit after launch and separation from the launch vehicle. The control nozzles for aligning the satellite are also chemical thrusters. For the fine orbit corrections during its expected 20-year service life, the satellite then uses the 5 kW ion thruster of the LIPS-300 type (a further development of the LIPS-200 from 2012) with xenon as a support mass. This only generates a low thrust of a maximum of 0.2 N, but it can be regulated in two stages, which means efficient use of the fuel supplies carried. In addition, the LIPS-300 has a specific impulse of 4000 s, which is ten times higher than that of conventional chemical thrusters . With the exclusive use of chemical engines, almost 3 tons of fuel would have to be carried for the orbit corrections of such a heavy satellite. The ion thruster reduces the fuel weight to 200 kg.

Depending on the payload weight, which can be between 1500 kg and 1800 kg, the DFH-5 bus has a takeoff weight of 8000–9000 kg. The solar cell wings deliver an output of at least 28 kW, of which 18 kW are available for the payloads. Waste heat of up to 9 kW generated by the payloads can be radiated into space via the cooling system . The DFH-5 bus is designed to last for 16 years, and the developers expect the technology to remain modern and applicable until around 2040. The platform designed for high orbits can be used not only for telecommunications, but also for long-range reconnaissance in the microwave and optical range, for scientific space exploration and for experiments. It is designed to be serviced in orbit, not only in terms of refueling, but also the replacement of components, a concept that is initially to be tested on the free-flying telescope of the modular space station .

Here is a comparison of the bus types:

DFH-3 DFH-3A DFH-3B DFH-4 DFH-5
Takeoff mass 2320 kg 2740 kg 3800 kg 5200 kg 8000 kg
Payload weight 230 kg 360 kg 450 kg 600 kg 1500 kg
Power supply (total) 1.7 kW 4 kW 5.5 kW 10.5 kW 30 kW
Power supply (payload) 1 kW 2.5 kW 4 kW 8 kW 18 kW
lifespan 8 years 12 years 15 years 15 years 16 years

Individual evidence

  1. ↑ Stephen Uhalley Jr .: A History of the Chinese Communist Party. Hoover Institution Press, Stanford 1988, pp. 117f.
  2. ↑ 历史 沿革. In: nssc.cas.cn. Retrieved June 19, 2019 (Chinese).
  3. ↑ 从 “东方 红 一号” 说起 ： 中国 为什么 要搞 人造卫星？ In: spaceflightfans.cn. April 26, 2020, accessed April 26, 2020 (Chinese). Contains photo and detailed synopsis of Zhao Jiuzhang's letter.
  4. ^ Qian Xuesen. In: qianxslib.sjtu.edu.cn. Retrieved August 8, 2020 (Chinese). P. 23.
  5. ↑ 赵竹青: 东方 红 一号 ”中国 第 一颗 人造卫星 诞生 内幕. In: scitech.people.com.cn. April 14, 2010, accessed June 17, 2019 (Chinese).
  6. ↑ Mark Wade: Chang Zheng 1 in the Encyclopedia Astronautica , accessed on June 17, 2019 (English).
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  15. ↑ 马丽: 我 首颗 直播 卫星 “鑫 诺 二号” 可能 成 太空 垃圾. In: scitech.people.com.cn. November 30, 2006, Retrieved June 16, 2019 (Chinese). In 2006, the conversion rate from euros to yuan was around 1:10. However, since this is a purely Chinese project, the purchasing power is to be used to assess the damage, where one yuan corresponds to about one euro.
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  21. ↑ 委内瑞拉 唯一 一颗 国有 通信 卫星 在 轨道 上 出现 故障. In: spaceflightfans.cn. March 26, 2020, accessed March 26, 2020 (Chinese).
  22. ↑ 委内瑞拉 唯一 一颗 国有 通信 卫星 正在 轨道 上 翻滚. In: tech.sina.cn. March 26, 2020, accessed March 26, 2020 (Chinese).
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