Shijian

Summary

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.[1][2][3][4]

Shijian Weixing
实践
Shíjiàn
Program overview
CountryChina People's Republic of China
OrganizationChina Academy of Space Technology (CAST)
PurposeUnknown, varied
StatusActive
Program history
Duration1971–present
First flight3 March 1971
Last flight8 January 2023
Successes37
Failures5
Launch site(s)
Vehicle information
Launch vehicle(s)
Shijian-23 prior to launch from Wenchang SLC

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.[5] 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 Shijan-series satellites are used to develop operational best practices and optimize the technologies previously tested on Shiyan-series satellites.[6] 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 edit

Shijian-17 edit

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.[7][8][9]

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."[10]

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.[11][12][13]

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.[14] 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."[14] 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."[15]

Shijian-18 edit

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,[16] 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.[17] 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.[18]

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.[19] 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.[20][21] The cause of the failure was later determined to be a faulty oxidizer turbopump, which has now been redesigned twice.[22] The rocket and payload crashed in the Pacific Ocean somewhere at the Philippine Sea.[23]

Shijian-21 edit

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.[24] 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."[25][26][27]

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.[28][29][30]

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.[31][32] 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.[25][26][33][29] 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."[29][34] Samson also praised commercial space situational awareness (SSA) providers for presenting the public and academia with satellite tracking capabilities previously exclusive to government.[29] China received criticism for its lack of transparency on Shijian-21's operations.[29]

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."[14] The 2023 report restated the same.[15]

Satellites edit

Name Launch Function Orbit Orbital apsis Inclination SCN COSPAR ID Launch site Launcher Status
Shijian 1 3 March 1971 Particle measurements of cosmic rays[35] LEO 266 km × 1826 km 69.9° 5007 1971-018A JSLC Long March 1 Decayed
Shijian 2 19 September 1981 Space dust/debris and EM study[35] LEO 232 km × 1598 km 59.4° 12845 1981-093D JSLC Feng Bao 1 Decayed
Shijian 2A 19 September 1981 Space dust/debris and EM study[35] LEO 232 km × 1615 km 59.4° 12843 1981-093B JSLC Feng Bao 1 Decayed
Shijian 2B 19 September 1981 Space dust/debris and EM study[35] LEO 232 km × 1608 km 59.4º 12842 1981-093A JSLC Feng Bao 1 Decayed
Shijian 3 N/A Earth observation[36][37][38] Cancelled, replaced by CBERS ZY-1[36]
Shijian 4 8 February 1994 Space radiation monitoring[39][35] HEO 210 km × 36125 km 28.6º 22996 1994-010A XSLC Long March 3A Decayed
Shijian 5 10 May 1999 Test new minisatellite platform, particle measurement[35] SSO 569 km × 849 km 98.8° 25731 1999-025B TSLC Long March 4B Decayed
Shijian 6-01B 8 September 2004 Space environment monitoring or ELINT[40] SSO 585.4 km × 585.2 km 97.7° 28414 2004-035B TSLC Long March 4B Operational
Shijian 6-01A 8 September 2004 Space environment monitoring or ELINT[40] SSO 579.8 km × 596.7 km 97.7° 28413 2004-035A TSLC Long March 4B Operational
Shijian 6-02A 23 October 2006 Space environment monitoring or ELINT[40] SSO 591.0 km × 593.4 km 97.8° 29506 2006-046B TSLC Long March 4B Operational
Shijian 6-02B 23 October 2006 Space environment monitoring or ELINT[40] SSO 583.1 km × 587.7 km 97.8° 29505 2006-046A TSLC Long March 4B Operational
Shijian 6-03A 25 October 2008 Space environment monitoring or ELINT[40] SSO 576.5 km × 599.1 km 97.8° 33409 2008-053B TSLC Long March 4B Operational
Shijian 6-03B 25 October 2008 Space environment monitoring or ELINT[40] SSO 573.9 km × 600.1 km 97.9° 33408 2008-053A TSLC Long March 4B Operational
Shijian 6-04A 6 October 2010 Space environment monitoring or ELINT[40] SSO 585.9 km × 600.1 km 97.8° 37180 2010-051B TSLC Long March 4B Operational
Shijian 6-04B 6 October 2010 Space environment monitoring or ELINT[40] SSO 570.6 km × 606.8 km 97.8° 37179 2010-051A TSLC Long March 4B Operational
Shijian 6-05A 10 December 2021 Space environment monitoring or ELINT[40] SSO 467.5 km × 475.4 km 97.3° 49961 2021-122A JSLC Long March 4B Operational
Shijian 6-05B 10 December 2021 Space environment monitoring or ELINT[40] SSO 467.5 km × 475.4 km 93.9° 49962 2021-122B JSLC Long March 4B Operational
Shijian 7 5 July 2005 Unknown SSO 557.4 km × 605.5 km 97.7° 28737 2005-024A JSLC Long March 2D Operational
Shijian 8 9 September 2006 Space agricultural experiments[41] LEO 177 km × 445 km 63.0° 29385 2006-035A JSLC Long March 2C Decayed
Shijian 9A 14 October 2012 Optical imaging, environmental monitoring[42] SSO 622 km × 647 km 98.0° 38860 2012-056A TSLC Long March 2C Operational
Shijian 9B 14 October 2012 Optical imaging, environmental monitoring, LWIR[42] SSO 623 km × 649 km 97.99° 38861 2012-056B TSLC Long March 2C Operational
Shijian 10 5 April 2016 Retrievable microgravity experiments[43] LEO 234 km × 268 km 42.89° 41448 2016-023A JSLC Long March 2D Decayed
Shijian 11-01 12 November 2009 Launch warning, IR tracking[44] SSO 689.7 km × 708.1 km 97.9° 36088 2009-061A JSLC Long March 2C Operational
Shijian 11-02 29 July 2011 Launch warning, IR tracking[44] SSO 678.5 km × 701.3 km 98.4° 37765 2011-039A JSLC Long March 2C Operational
Shijian 11-03 6 July 2011 Launch warning, IR tracking[44] SSO 689.8 km × 704.1 km 97.8° 37730 2011-030A JSLC Long March 2C Operational
Shijian 11-04 18 August 2011 Launch warning, IR tracking[44] (Launch Failure) JSLC Long March 2C Payload lost in rocket failure[45]
Shijian 11-05 15 July 2013 Launch warning, IR tracking[44] SSO 689.4 km × 703.3 km 98.2° 39202 2013-035A JSLC Long March 2C Operational
Shijian 11-06 31 March 2014 Launch warning, IR tracking[44] SSO 692.3 km × 713.6 km 98.1° 39624 2014-014A JSLC Long March 2C Operational
Shijian 11-07 28 September 2014 Launch warning, IR tracking[44] SSO 690.6 km × 706.3 km 98.1° 40261 2014-059A JSLC Long March 2C Operational
Shijian 11-08 27 October 2014 Launch warning, IR tracking[44] SSO 685.0 km × 701.7 km 98.2° 40286 2014-066A JSLC Long March 2C Operational
Shijian 12 15 June 2010 Scientific research[46] SSO 575 km × 599 km 97.68° 36596 2010-027A JSLC Long March 2D Operational
Shijian 13 12 April 2017 High-throughput communications[47][48][49] GEO 35,765.3 km × 35,823.8 km 0.1° 42662 2017-018A XSLC Long March 3B Operational
Shijian 15 19 July 2013 Unknown payload deployment[50] SSO 670.6 km × 678.4 km 98.0° 39210 2013-037C TSLC Long March 4C Operational
Shijian 16-01 25 October 2013 Space environment monitoring or SIGINT[51][52] LEO 599 km × 616 km 74.98° 39358 2013-057A JSLC Long March 4B Operational
Shijian 16-02 29 June 2016 Space environment monitoring or SIGINT[51][52] LEO 596 km × 616 km 75.00° 41634 2016-043A JSLC Long March 4B Operational
Shijian 17 3 November 2016 Communications and debris inspection or counterspace[53] GEO 35,827.1 km × 35,835.4 km 2.2° 41838 2016-065A WSLC Long March 5 Operational
Shijian 18 2 July 2017 Test of new DFH-5 platform, telecom[54] (Launch Failure) WSLC Long March 5 Payload lost in rocket failure[55]
Shijian 19 TBA Returnable microgravity experiments[56][57] Planned: not yet launched JSLC Long March 2D Planned
Shijian 20 27 December 2019 Test of new DFH-5 platform, experimental quantum telecom[58][59] GEO 35,774.9 km × 35,814.1 km 1.347° 44910 2019-097A WSLC Long March 5 Operational
Shijian 21 24 October 2021 Debris clean-up or counterspace[60][61] GEO 36,217.7 km × 36,217.7 km 8.580° 49330 2021-094A XSLC Long March 3B Operational
Shijian 21 (subsat) 24 October 2021 Unknown[61][62] 49382 2021-094C XSLC Long March 3B Operational
Shijian 23 8 January 2023 Classified GEO 35,769.1 km × 35,816.8 km 0.6° 55131 2023-002A WSLC Long March 7A Operational
Shijian 23 (subsat) 8 January 2023 Unknown[63] 55180 2023-002C WSLC Long March 7A Operational
Sources: NORAD, NASA, USSPACECOM, Celestrak, Gunter's Space Page

See also edit

References edit

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