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Shijian Weixing

实践 Shíjiàn
Program overview
Country	People's Republic of China
Organization	China Academy of Space Technology (CAST)
Purpose	Unknown, varied
Status	Active
Program history
Duration	1971–present
First flight	3 March 1971
Last flight	27 September 2024
Successes	38
Failures	5
Launch site(s)	TSLC JSLC XSLC WSLS
Vehicle information
Launch vehicle(s)	Feng Bao 1 Long March 1 Long March 2C Long March 2D Long March 3A Long March 3B Long March 4B Long March 4C Long March 5 Long March 7A

Shijian (simplified Chinese: 实践; traditional Chinese: 實踐; pinyin: Shíjiàn; lit. 'Practice', abbr. "SJ") is a series of satellites built and operated by the People's Republic of China. Some Shijian-series satellites have drawn significant concerns from the United States government and space observers who cite unannounced launches, undisclosed sub-satellites deployed in orbit, unusual orbital maneuvers, and demonstrated rendezvous proximity operations (RPO) including the close inspection and towing of other satellites.

Little is known about the series and what differentiates it from other experimental satellite series launched by China such as the Chuangxin (Chinese: 创新; pinyin: Chuàngxīn; lit. 'Innovation') series or Shiyan (Chinese: 实验; pinyin: Shíyàn; lit. 'Experiment') series. The China Aerospace Studies Institute of the United States Air Force asserts that Shiyan-series satellites play an earlier role in the systems development process testing various new technologies on a single bus while Shijian-series satellites are used to develop operational best practices and optimize the technologies previously tested on Shiyan-series satellites. In this regard, "Shijian" should be translated as "best practice", or "put into practice" while "Shiyan" ought to be translated as "experiment", "pilot", or "trial".

Notable satellites

Shijian-17

Launched into geostationary orbit aboard a Long March 5 rocket on 3 November 2016 from Wenchang Space Launch Site, Shijian -17 is the first Chinese satellite to bear a robotic arm. Observers question the robotic arm's dual-purposes for space debris cleanup and kinetic attacks against adversary satellites.

In an April 2021 written statement to the US Senate Armed Services Committee, General James H. Dickinson, Commander of United States Space Command (USSPACECOM) was the first US official to speak publicly on Shijian-17 warning of its counterspace capabilities. General Dickinson wrote "Beijing actively seeks space superiority through space and space attack systems. One notable object is the Shijian-17, a Chinese satellite with a robotic arm. Space-based robotic arm technology could be used in a future system for grappling other satellites."

Shijian-17 has also prompted concern among observers who have tracked Shijian-17's unique orbital maneuvers. Since its launch, Shijian-17 has occupied a wide span of orbital positions within its geostationary orbit to dynamically adjust its position relative to neighboring satellites. These varied positions have ranged from 37.7°E over Africa to 180°E over the Marshall Islands, uncharacteristic of other satellites designed for communications. Shijian-17 has also positioned itself as close as 55 kilometers to other satellites for periods of a week or more while other geostationary satellites maintain an average 207-kilometer separation distance.

Shijian-17's robotic arm also earned mentions in the U.S. Office of the Secretary of Defense's congressionally-mandated Annual Report to Congress: Military and Security Developments involving the People's Republic of China. The 2022 report, the first to mention Shijian satellites by name, announced "The Shijian-17 is a Chinese satellite with a robotic arm. Space-based robotic arm technology could be used in a future system for grappling other satellites." The 2023 report specified "The Shijian-17 was the PRC's first satellite with a robotic arm, technology that could be used in a future system for grappling adversary satellites."

Shijian-18

Shijian-18 was a Chinese communications and technology demonstration satellite developed and launched by the China Academy of Space Technology on 2 July 2017. It was the maiden flight of the DHF-5 satellite bus, which is designed with 16-year lifespan. Shijian-18 carried 18 experiments on board involving communications and space telescopes. It was lost after a malfunction on the Long March 5 rocket carrying the satellite. It would have been the heaviest geostationary satellite at the time of its launch, with a launch mass of 7,600 kg (16,800 lb). The satellite incorporated a high-thrust ion propulsion system, a large trussed structure and a higher payload capacity. More specifically, it used the LIPS-300 xenon thruster for orbit keeping, developed by the Lanzhou Institute of Physics. It was planned for the LIPS-300 system to be fully certified in this mission so that it could be used for geostationary and deep-space operations. The satellite would operate at the Ka band with 70 Gb/s capacity, capable of providing broadband internet to whole mainland China.

Shijian-18 launched from the Wenchang Space Launch Site on 2 July 2017 at 11:23 UTC on board a Long March 5 rocket to a geostationary orbit. It was the rocket's second flight, the first being to launch Shijian-17. The rocket encountered an anomaly shortly after launch, causing it to switch into a gentler trajectory. However, 45 minutes into the flight, it was declared a failure, with the loss of the payload. The cause of the failure was later determined to be a faulty oxidizer turbopump, which has now been redesigned twice. The rocket and payload crashed in the Pacific Ocean somewhere at the Philippine Sea.

Shijian-21

In October 2021, China launched Shijian 21 (SJ-21) from Xichang Space Launch Center (XSLC) aboard a Long March 3B rocket into geosynchronous transfer orbit (GTO). Atypically, China issued no notifications prior to the launch confirming only after the satellite's successful launch. China's official state news media organization, Xinhua News Agency, described SJ-21 as an On-Orbit Service, Assembly, and Manufacturing (OSAM) satellite that would be "mainly used to test and verify space debris mitigation technologies."

A month after its launch, SJ-21 drew some suspicion from space observers as an object, described to be an undeclared sub-satellite, began orbiting closely alongside SJ-21 shortly after its entry into geosynchronous orbit (GEO). The object was initially cataloged as an apogee kick motor (AKM) by the US Space Force's 18th Space Defense Squadron (SDS), however many doubt that a discarded motor would maintain the constant and proximate orbit with SJ-21 instead of gradually drifting away. SJ-21 drew further suspicion in January 2022 when, according to commercial space monitoring firm ExoAnalytic Solutions, SJ-21 went "missing" from its orbital slot to dock with defunct Beidou G2 (Compass G2) navigation satellite capitalizing on the inability of optical satellites to track space-objects during the day. Shijian-21 then moved to an orbit 3,000 kilometers higher where it released the Beidou G2 satellite into graveyard orbit and returned to GEO.

Many observers suspect the spacecraft, like many of China's Yaogan and Gaofen satellites, serve primarily military purposes under the cover of more mundane missions. With SJ-21's demonstrate capability to tug satellites from their orbit and China's increasing interest in space power, the spacecraft likely also offers the Chinese government a tool for counterspace operations. Victoria Samson, the Washington Office director for the Secure World Foundation said "You could look at China working to develop the capability to remove inactive satellites on orbit as a way in which it is being a responsible space actor and cleaning up debris that it caused. Or you could use the lens that a lot of the US-based China watchers use and say that this could indicate that China is developing an on-orbit offensive capability." Samson also praised commercial space situational awareness (SSA) providers for presenting the public and academia with satellite tracking capabilities previously exclusive to government. China received criticism for its lack of transparency on Shijian-21's operations.

First mentioned by name in the 2022 China Military Power Report, the U.S. Office of the Secretary of Defense writes "China has launched multiple satellites to conduct scientific experiments on space maintenance technologies and is conducting research on space debris cleanup; the most recent launch was the Shijian-21 launched into GEO in October 2021. In January 2022, Shijian-21 moved a derelict BeiDou navigation satellite into a high graveyard orbit above GEO." The 2023 report restated the same.

Satellites

See also

• Yaogan
• Gaofen
• Fengyun

References

1. Dickinson, General James H. (21 April 2021). United States Space Command Presentation to the Senate Armed Services Committee U.S. Senate (PDF) (Report). Archived (PDF) from the original on 26 August 2022. Retrieved 2 September 2022.
2. Roberts, Thomas G. (31 March 2021). "Unusual Behavior in GEO: SJ-17". Aerospace Security, Center for Strategic and International Studies (CSIS). Archived from the original on 1 September 2022. Retrieved 2 September 2022.
3. Tiwari, Sakshi (17 February 2022). "Strangling Like A Python, China Says Its Powerful 'Robotic Snake' Can Crush Enemy Satellites Like Never Before". The Eurasian Times. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
4. Jones, Andrew (27 January 2022). "China's Shijian-21 towed dead satellite to a high graveyard orbit". SpaceNews. Archived from the original on 3 February 2023. Retrieved 2 September 2022.
5. Chia, Henry (7 December 2021). "What we know about China's Shijian-class satellites". asiaMARKETS. Archived from the original on 28 August 2022. Retrieved 2 September 2022.
6. Burke, Kristin (28 March 2022). "Initial Analysis of Two Chinese Satellite Series: Shi Jian and Shi Yan" (PDF). China Aerospace Studies Institute (March 2022). Archived (PDF) from the original on 2023-10-07. Retrieved 2023-12-02.
7. Dan, Robitzski (24 May 2021). "The Head of US Space Command Fears China's Giant Robot Arms". Futurism.com. Archived from the original on 6 November 2023. Retrieved 6 November 2023.
8. Moriyasu, Ken (21 April 2021). "China can 'grapple' US satellites with robotic arm, commander says". Nikkei Asia. Archived from the original on 6 November 2023. Retrieved 6 November 2023.
9. Zhen, Liu (22 May 2021). "China space station's giant robotic arm sparks concerns in US". South China Morning Post. Archived from the original on 6 November 2023. Retrieved 6 November 2023.
10. Dickinson, General James H. (21 April 2021). United States Space Command Presentation to the Senate Armed Services Committee U.S. Senate (PDF) (Report). Archived (PDF) from the original on 26 August 2022. Retrieved 2 September 2022.
11. Roberts, Thomas G. (31 March 2021). "Unusual Behavior in GEO: SJ-17". Aerospace Security, Center for Strategic and International Studies (CSIS). Archived from the original on 1 September 2022. Retrieved 2 September 2022.
12. Clark, Colin (18 April 2018). "China Satellite SJ-17, Friendly Wanderer". Breaking Defense. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
13. Tiwari, Sakshi (17 February 2022). "Strangling Like A Python, China Says Its Powerful 'Robotic Snake' Can Crush Enemy Satellites Like Never Before". The Eurasian Times. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
14. ^ 2022 Military and Security Developments Involving the People's Republic of China, Annual Report to Congress (PDF). Arlington, VA: United States Department of Defense. 2022. p. 93. Archived (PDF) from the original on 2023-06-25. Retrieved 2022-11-30.
15. ^ 2023 Military and Security Developments Involving the People's Republic of China, Annual Report to Congress (PDF). Arlington, VA: United States Department of Defense. 2023. p. 103. Archived (PDF) from the original on 2023-11-07. Retrieved 2023-11-06.
16. "Shijian-18 – CZ-5 – Shijian-18 | Spaceflight101". Archived from the original on 2021-12-09. Retrieved 2021-12-09.
17. "Shijian-18 – CZ-5 – Shijian-18 | Spaceflight101". Archived from the original on 2021-12-09. Retrieved 2021-12-09.
18. "Shijian-18 – CZ-5 – Shijian-18 | Spaceflight101". Archived from the original on 2021-12-09. Retrieved 2021-12-09.
19. Clark, Stephen. "China launches Long March 5, one of the world's most powerful rockets – Spaceflight Now". Archived from the original on 2021-12-09. Retrieved 2021-12-09.
20. Clark, Stephen. "China launches Long March 5, one of the world's most powerful rockets – Spaceflight Now". Archived from the original on 2021-12-09. Retrieved 2021-12-09.
21. Goh, Deyana (2017-07-03). "Long March 5-Y2 fails, Shijian-18 satellite lost". SpaceTech Asia. Archived from the original on 2021-12-09. Retrieved 2021-12-09.
22. "Successful Long March 5 launch opens way for China's major space plans". SpaceNews. 2019-12-27. Archived from the original on 2021-05-06. Retrieved 2021-12-09.
23. Clark, Stephen. "China launches Long March 5, one of the world's most powerful rockets – Spaceflight Now". Archived from the original on 2021-12-09. Retrieved 2021-12-09.
24. Chia, Henry (7 December 2021). "What we know about China's Shijian-class satellites". asiaMARKETS. Archived from the original on 28 August 2022. Retrieved 2 September 2022.
25. ^ Mowthorpe, Matthew; Trichas, Markos (1 August 2022). "A review of Chinese counterspace activities". The Space Review. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
26. ^ Burke, Kristin (9 December 2021). "China's SJ-21 Framed as Demonstrating Growing On-Orbit Servicing, Assembly, and Manufacturing (OSAM) Capabilities" (PDF). China Aerospace Studies Institute (Dec 2021). Archived (PDF) from the original on 2022-12-09. Retrieved 2023-12-02.
27. Tingley, Brett (27 January 2022). "A Chinese Satellite Just Grappled Another And Pulled It Out Of Orbit". The War Zone (magazine). Archived from the original on 1 September 2022. Retrieved 2 September 2022.
28. SJ-21 Quick Look Report (January 2022) (Video presentation). ExoAnalytic Solutions. 28 January 2022. Archived from the original on 28 August 2022. Retrieved 2 September 2022.
29. ^ Jones, Andrew (27 January 2022). "China's Shijian-21 towed dead satellite to a high graveyard orbit". SpaceNews. Archived from the original on 3 February 2023. Retrieved 2 September 2022.
30. Hitchens, Theresa (26 January 2022). "China's SJ-21 'tugs' dead satellite out of GEO belt: Trackers". Breaking Defense. Archived from the original on 10 March 2022. Retrieved 2 September 2022.
31. Barbosa, Rui C. (22 April 2009). "Chinese launch again with YaoGan Weixing-6 remote sensing satellite". nasaspaceflight.com. NASASpaceFlight.com. Archived from the original on 5 February 2022. Retrieved 23 April 2009.
32. "2006年4月27日 "遥感卫星一号"成功发射". www.xinhuanet.com. Xinhuanet. 27 April 2006. Archived from the original on 24 June 2021. Retrieved 16 June 2021.
33. Makichuk, Dave (8 November 2021). "Space Force tracks Shijian-21 satellite 'companion'". Asia Times. Archived from the original on 6 December 2022. Retrieved 2 September 2022.
34. Kramer, Herbert J. (31 January 2022). "Shijian-21". eoPortal. Archived from the original on 28 August 2022. Retrieved 2 September 2022.
35. ^ "Shi Jian". eoPortal. 15 June 2012. Archived from the original on 28 August 2022. Retrieved 2 September 2022.
36. ^ Chia, Henry (7 December 2021). "What we know about China's Shijian-class satellites". asiaMARKETS. Archived from the original on 28 August 2022. Retrieved 2 September 2022.
37. Krebs, Gunter D. (21 July 2019). "SJ 3". Gunter's Space Page. Archived from the original on 28 August 2022. Retrieved 2 September 2022.
38. Krebs, Gunter D. (26 December 2021). "CBERS 1, 2, 2B / ZY-1 01, 02, 02B". Gunter's Space Page. Archived from the original on 7 October 2022. Retrieved 2 September 2022.
39. Krebs, Gunter D. (21 July 2019). "SJ 4". Gunter's Space Page. Archived from the original on 28 August 2022. Retrieved 2 September 2022.
40. ^ Krebs, Gunter D. (23 March 2022). "SJ 6-01, ..., 6-05". Gunter's Space Page. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
41. Krebs, Gunter D. (14 September 2020). "SJ 8". Gunter's Space Page. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
42. ^ "Shi Jian-9". eoPortal. 26 October 2012. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
43. Christy, Robert (20 April 2016). "Shijian 10". Orbital Focus. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
44. ^ Wade, Mark. "SJ-11". Astronautix. Archived from the original on 2022-05-20. Retrieved 2022-09-02.
45. Krebs, Gunter D. (14 September 2020). "SJ 11". Gunter's Space Page. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
46. Barbosa, Rui C. (14 June 2010). "China launch Shi Jian-12 satellite on research mission". NASA Spaceflight. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
47. "China to help Pakistan build larger capacity telecom network". The Nation (Pakistan). 21 February 2017. Archived from the original on 1 December 2020.
48. "China to launch first high-throughput communications satellite in April". Space Daily. 21 February 2017. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
49. "China Focus: China launches 1st high-throughput communications satellite". Xinhua News Agency. 12 April 2017. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
50. Christy, Robert (10 August 2013). "Shijian-15". Orbital Focus. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
51. ^ "SJ 16-02". N2YO. Archived from the original on 2022-09-01. Retrieved 2022-09-02.
52. ^ Krebs, Gunter D. (11 April 2021). "SJ 16". Gunter's Space Page. Archived from the original on 1 September 2022. Retrieved 2 September 2022.
53. "In-Space Eavesdropping? – China's Shijian-17 completes High-Altitude Link-Up". Spaceflight101. Archived from the original on 2022-09-01. Retrieved 2022-09-02.
54. "Shijian-18 – CZ-5 – Shijian-18 | Spaceflight101". Archived from the original on 2021-12-09. Retrieved 2021-12-09.
55. Krebs, Gunter D. (22 December 2020). "SJ 18". Gunter's Space Page. Archived from the original on 9 December 2021. Retrieved 2 September 2022.
56. "广梅一号"为苏区振兴插上翅膀" ["Guangmei No. 1" adds wings to the revitalization of the Soviet area]. Sina News (in Chinese). 11 June 2019. Archived from the original on 2022-08-28. Retrieved 2022-09-02.
57. Lanyue, Hu (10 July 2019). Yiming, Yang Chenggao (ed.). "能送半吨货往返太空！我国新一代商业返回式卫星拟明年首发" [Can send half a ton of cargo to and from space! my country's new generation of commercial returnable satellites to be launched next year]. China Aerospace Science and Technology Corporation (in Chinese). Archived from the original on 28 August 2022. Retrieved 2 September 2022.
58. "Shijian-20". Next Spaceflight. Archived from the original on 2022-08-28. Retrieved 2022-09-02.
59. Chen, Stephen (27 July 2022). "China launches new satellite in 'important step' towards global quantum communications network". South China Morning Post. Archived from the original on 28 August 2022. Retrieved 2 September 2022.
60. Tingley, Brett (27 January 2022). "A Chinese Satellite Just Grappled Another And Pulled It Out Of Orbit". The War Zone (magazine). Archived from the original on 1 September 2022. Retrieved 2 September 2022.
61. ^ Jones, Andrew (27 January 2022). "China's Shijian-21 towed dead satellite to a high graveyard orbit". SpaceNews. Archived from the original on 3 February 2023. Retrieved 2 September 2022.
62. Makichuk, Dave (8 November 2021). "Space Force tracks Shijian-21 satellite 'companion'". Asia Times. Archived from the original on 6 December 2022. Retrieved 2 September 2022.
63. Jones, Andrew (27 January 2023). "Classified Chinese satellite releases small object in orbit". Space. Archived from the original on 27 January 2023. Retrieved 27 January 2023.

• Satellite series
• Spacecraft launched by Long March rockets
• Satellites of China