Shijian: Difference between revisions

 

=== Shijian-17 ===

 

 

Shijian-17 has also prompted concern among observers who have tracked Shijian-17's unique [[Orbital maneuver|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.<ref name=":92">{{Cite web |last=Roberts |first=Thomas G. |date=31 March 2021 |title=Unusual Behavior in GEO: SJ-17 |url=https://aerospace.csis.org/data/unusual-behavior-in-geo-sj-17/ |website=Aerospace Security, Center for Strategic and International Studies (CSIS) |access-date=2 September 2022 |archive-date=1 September 2022 |archive-url=https://web.archive.org/web/20220901014917/https://aerospace.csis.org/data/unusual-behavior-in-geo-sj-17/ |url-status=live }}</ref><ref>{{Cite news |last=Clark |first=Colin |date=18 April 2018 |title=China Satellite SJ-17, Friendly Wanderer |work=Breaking Defense |url=https://breakingdefense.com/2018/04/china-satellite-sj-17-friendly-wanderer/ |access-date=2 September 2022 |archive-date=1 September 2022 |archive-url=https://web.archive.org/web/20220901014855/https://breakingdefense.com/2018/04/china-satellite-sj-17-friendly-wanderer/ |url-status=live }}</ref><ref name=":102">{{Cite news |last=Tiwari |first=Sakshi |date=17 February 2022 |title=Strangling Like A Python, China Says Its Powerful 'Robotic Snake' Can Crush Enemy Satellites Like Never Before |work=The Eurasian Times |url=https://eurasiantimes.com/china-says-its-powerful-robotic-snake-can-crush-enemy-satellites/ |access-date=2 September 2022 |archive-date=1 September 2022 |archive-url=https://web.archive.org/web/20220901014920/https://eurasiantimes.com/china-says-its-powerful-robotic-snake-can-crush-enemy-satellites/ |url-status=live }}</ref>

 

=== Shijian-21 ===

 

 

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.<ref name="NSF">{{cite web |last=Barbosa |first=Rui C. |date=22 April 2009 |title=Chinese launch again with YaoGan Weixing-6 remote sensing satellite |url=http://www.nasaspaceflight.com/2009/04/chinese-launch-again-with-yaogan-weixing-6-remote-sensing-satellite/ |access-date=23 April 2009 |website=nasaspaceflight.com |publisher=NASASpaceFlight.com |archive-date=5 February 2022 |archive-url=https://web.archive.org/web/20220205102900/http://www.nasaspaceflight.com/2009/04/chinese-launch-again-with-yaogan-weixing-6-remote-sensing-satellite/ |url-status=live }}</ref><ref name="Xinhua">{{cite web |date=27 April 2006 |title=2006年4月27日 "遥感卫星一号"成功发射 |url=http://www.xinhuanet.com/science/2018-04/27/c_137140219.htm |url-status=dead |archive-url=https://web.archive.org/web/20210624195949/http://www.xinhuanet.com/science/2018-04/27/c_137140219.htm |archive-date=24 June 2021 |access-date=16 June 2021 |website=www.xinhuanet.com |publisher=Xinhuanet}}</ref> 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.<ref name=":0" /><ref name=":1" /><ref name=":4">{{Cite news |last=Makichuk |first=Dave |date=8 November 2021 |title=Space Force tracks Shijian-21 satellite 'companion' |work=[[Asia Times]] |url=https://asiatimes.com/2021/11/us-detects-companion-orbiting-alongside-shijian-21/ |access-date=2 September 2022 |archive-date=6 December 2022 |archive-url=https://web.archive.org/web/20221206065554/https://asiatimes.com/2021/11/us-detects-companion-orbiting-alongside-shijian-21/ |url-status=live }}</ref><ref name=":22" /> 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."<ref name=":22" /><ref>{{Cite web |last=Kramer |first=Herbert J. |date=31 January 2022 |title=Shijian-21 |url=https://www.eoportal.org/satellite-missions/shijian-21#usa-270-chinese-shiyan-12-encounter |website=eoPortal |access-date=2 September 2022 |archive-date=28 August 2022 |archive-url=https://web.archive.org/web/20220828215719/https://www.eoportal.org/satellite-missions/shijian-21#usa-270-chinese-shiyan-12-encounter |url-status=live }}</ref> Samson also praised commercial space situational awareness (SSA) providers for presenting the public and academia with satellite tracking capabilities previously exclusive to government.<ref name=":22" /> China received criticism for its lack of transparency on Shijian-21's operations.<ref name=":22" />

 

 

== Satellites ==