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Launches and Orbital Operations


Tyneside, UK
2021 Dec 8
Wednesday, Day 342

Maintained by:






Mission Events 2021:




























Mission Events 2020:



Flashback:








Timelines:




Shijian X

2021-076 SMA


China announced that its TJS 3 (Communications Technology Experiment Satellite 3) was launched 2018 December 24 but gave no details of the orbit. Space-Track catalogued three items - the CZ 3C rocket upper stage in transfer orbit, plus TJS 3 in GEO accompanied by another object it called "TJS-3 AKM", an abbreviation for 'apogee kick motor'.

It soon became obvious that the 'AKM' is a satellite in its own right rather than being a rocket stage. In hindsight it is probably the actual TJS 3 satellite. The object Space-Track has tagged with the name has shown behaviour more in keeping with the geosynchronous versions of a Shijian satellite.

Soon after launch the Shijian-like vehicle went its own way, making close approaches to several other satellites, including Russia's Luch-Olympus. After three years of wandering it returned to where it started, alongside its companion from the original launch.


Launch

The CZ 3C launch vehicle placed its own upper stage and one other object into geosynchronous transfer orbit. The payload then circularised its orbit at geosynchronous altitude and drifted to 59° east longitude where it came to rest around December 27. Its precise arrival date is not known because no element sets were published for the drift orbit.


Post-launch Events

On 2019 January 1, Space-Track published its first element set for object 43917/2018-110C. It seems to have 'come into existence' on December 31 in a similar orbit to 43874/2018-110A. The implication is that the two objects separated from each other on that day, once geosynchronous orbit had been established.

Objects detected in orbit are:

Probable IdentityCatalogue NoDesignationSpace-Track Name
Shijian 'X'438742018-110ATJS-3
TJS 3439172018-110CTJS-3 AKM
CZ 3C upper stage438752018-110BCZ-3C R/B


From this point on, satellites are referred to by the names in the first column of the table above.

The zarya.info listing for the launch can be found here.


Long Term Behaviour

Since that date 43917/2018-110C has remained near 59° east, echoing the general behaviour of other geosynchronous TJS satellites.

43874/2018-110A on the other hand has spent the past three years wandering around the geosynchronous belt, approaching other satellites and spending co-orbiting with them, exhibiting behaviour more akin to a Shijian mission - hence suggesting the object should be named Shijian 'X'.

Of the series of satellites named 'Shijian', numbers 13, 17 and 20 were all sent to geosynchronous altitude and Shijian 'X' has spent time alongside them all. Shijian 7 was placed in low orbit and was involved in manoeuvres and activities of a similar nature to those now unfolding in GEO.


Shijian 'X' Chronology

Dates, times and locations in the list below can be matched to the plot at the top of the page.

DateEvent
2018 Dec 31Separates from TJS 3 to sit alongside it at 59° east
2019 May 20Commences 2.5°/day eastward drift around the GEO belt
2019 Jul 6Arrives at 173° east
2020 Aug 4Departs 173° east where it had remained for almost 12 months, heads westwards at 1.25°/day
2020 Aug 9Reaches 163° east

Simultaneously - Shijian 17, that had been stationed at 163° east since 2020 Apr 25, commences a move westwards, matching the speed of Shijian 'X' and then running alongside it
2020 Sep 9Shijian 17 reduces its drift rate, ceases station-keeping and falls behind
2020 Sep 22Arrives at 111° east and matches orbit with Shijian 13
2020 Dec 18Departs 111° east, moving westwards at 0.5°/day
2020 Dec 30Shijian 20 departs its station at 125° east, moving westwards at 1°/day
2021 Jan 21Arrives at 88° east
2021 Feb 3Shijian 20 arrives alongside Shijian 'X' at 88° east and commences a period of joint operations where both satellites exhibit very small orbit changes

Docking between the two vehicles on one or more occasions is a possibility
2021 Aug 30Departs 88° east, moving westward at 0.5°/day
2021 Sep 27Luch-Olympus departs 57° east
2021 Oct 4Luch-Olympus arrives 60° east
2021 Oct 6Shijian 'X' passes 66 km above Luch-Olympus at 22:08 UTC, moving west
2021 Oct 8Shijian 'X' ceases its westward drift and comes to rest near TJS 3 from which it separated 2018 Dec 31


Possible Precursor Mission

On 2013 July 19, China launched a multi-payload mission to LEO. The satellites performed several orbit manoeuvres including some that appeared to show that one or more satellites had linked up with each other. They also performed joint manoeuvres with Shijian 7 (28737/2005-024A) a low orbit satellite carrying the same same series name as the ones now operating in GEO. It was launched in 2005.

Current GEO operations may be building on the tests carried out in 2013. They have the potential to lead to satellite servicing and repair missions but some analysts point out that they also demonstrate the potential ability to attack and disable a satellite owned by a rival state.


Encounter with Luch-Olympus (40258/2015-058A)

This is a Russian satellite launched in 2014. Since then, it has been wandering the GEO belt and occasionally settling down next to satellites owned by other nations. It is commonly accepted as being an inspection vehicle, monitoring other satellites' uplinks and downlinks and collecting images.

2021 September 27 it was stationed at 57° east where it had been for about two months. In brief:

NameLocationStatus
Shijian 'X'68° eastmoving west 0.75°/day
TJS 359° eaststationary
Luch-Olympus57° eaststationary


Russian controllers may have seen an opportunity to gain some intelligence on Shijian 'X', but if it was heading for rendezvous with TJS 3, it would never reach the Luch Olympus location. On September 27, Luch-Olympus commenced a move to 60° east. It reached there on October 4 putting it into a position where Shijian 'X' would pass by before catching up with TJS 3:

NameLocationStatus
Shijian 'X'62° eastmoving west 0.75°/day
Luch-Olympus60° eaststationary
TJS 359° eaststationary


Luch-Olympus had been placed in a postion where no amount of orbital manoeuvring by Shijian 'X' could prevent it passing by under good lighting conditions.

On October 6 at 22:08 UTC, the two satellites made their closest conjunction with each other. The Russian satellite was about 66 kilometers below its target, which was set against a dark sky and with the Sun shining from behind the camera. Its trajectory meant Shijian 'X' stayed within 100 kilometres for about five and a half hours.


Homecoming

Around midnight 2021 Oct 7, Shijian 'X' drifted past TJS 3 at 59°.0 east longitude. A few hours later, it fired thrusters to stop the drift and settled at 59°.3 east, about 250 kilometres away from the companion satellite that it had left behind a little over three years earlier.



Page Date - 2021 Oct 3
Rendezvous estimate updated from Oct 10 - 2021 Oct 6
Luch-Olympus notes added - 2021 Oct 7
Events of 2021 Oct 7/8 added - 2021 Oct 9
Chronology updated in real time

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