Orbital Focus - International Spaceflight Facts and Figures
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Launches and Orbital Operations


Tyneside, UK
2022 Aug 10
Wednesday, Day 222

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Yaogan 34 - The Shadow

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Yaogan 31

During 2021, China completed its constellation of Yaogan 31 satellites, having set-up four groups of them in separated orbit planes.

The oldest group, from 2018, was probably a pathfinder with the later three sets forming a fully operational system.


Yaogan 34-01

2021 April 30 saw the first Yaogan 34 appear. Its orbit parameters were similar to the Yaogan 31s but the Right Ascension of the Asending Node was 3° to the east of that of the second Yaogan 31 Group. Yaogan 34 then moved to a position 36° of orbit arc behind the Yaogan 31s. It was allowed to drift but when the gap had a reduced to 32°, an orbit 'nudge' sent it drifting in the opposite direction. It then settled into a routine where regular orbit adjustments kept it between 32° and 36° behind Yaogan 31. From its position, Yaogan 34-01 has the other satellites in view all of the time.

A combination of the 3° spacing in RAAN and the on-orbit spacing between Yaogan 34-01 and its Yaogan 31 companions ensures that it passes along a near-identical ground track but ten minutes behind them. The RAAN difference takes account of the Earth's rotation over that ten minute period.


What Are They Doing?

The Yaogan 31s probably have an electronic intelligence gathering (ELINT) task, particularly over the world's oceans away from dry land. They orbit in a triangular formation about 120 kilometres from each other. Differences in Doppler shift of transmissions detected from the Earth's surface would allow the location to be pinpointed. They may also be able to perform as a long baseline interferometer.

Yaogan 31s are probably tasked with characterising the radio and radar transmissions that they detect. The job of Yaogan 34 may be to take a more forensic look at specific 'interesting' transmissions detected by its companion Yaogan 31 Group.


Yaogan 34-02

The second Yaogan 34 was launched 2022 Mar 17. It had been expected as a result of air navigation warnings that pointed to its launch time, orbital inclination and RAAN.

Its RAAN mirrored that of its predecessor but related to Yaogan 31 Group 3.

The launch time and target orbit were selected very carefully and it was injected into a near identical orbit to Yaogan 31 Group 3 and precisely 34° behind it. The operational relationship was set up from the moment of arrival on orbit.

Yaogan 34-02


NOTE - 'wiggles' in the plotted lines are due to the way that the separation distance is calculated.



Summary of the Launches Involved

These are the four launches and eight satellites now incorporated into the joint Yaogan 31 and Yaogan 34 constellation.

2021-007
CZ 4C
Jiuquan Space Centre
2021 Jan 29, 04:47
Yaogan 31-02 Outlier
2021-007A
47532
in space
Remote sensing satellite described as used for electromagnetic environment surveys and other related technology tests. Orbiting in close formation with the other two satellites from the launch, its purpose may be signals or electronic intelligence gathering over the world's oceans, a similar task to the US NOSS triplet formations that orbited at a similar altitude and inclination. Formation was set up Feb 24 after one month of phasing manoeuvres.

epoch (UTC)         
s-m axis
( km )
ecc    perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Jan 29, 22:0474720.000410911097107.1363.41274
2021 Feb 02, 10:4874930.001011081123107.5963.41261
2021 Mar 03, 08:4674680.000910831097107.0563.41284
Yaogan 31-02 Trailer
2021-007B
47533
in space
Remote sensing satellite described as used for electromagnetic environment surveys and other related technology tests. Orbiting in close formation with the other two satellites from the launch, its purpose may be signals or electronic intelligence gathering over the world's oceans, a similar task to the US NOSS triplet formations that orbited at a similar altitude and inclination. Formation was set up Feb 24 after one month of phasing manoeuvres.

epoch (UTC)         
s-m axis
( km )
ecc    perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Jan 30, 01:3974720.000510911098107.1463.41276
2021 Feb 02, 10:3174580.001210711088106.8363.41348
2021 Mar 03, 08:4674680.000910831097107.0563.41285
Yaogan 31-02 Leader
2021-007E
47536
in space
Remote sensing satellite described as used for electromagnetic environment surveys and other related technology tests. Orbiting in close formation with the other two satellites from the launch, its purpose may be signals or electronic intelligence gathering over the world's oceans, a similar task to the US NOSS triplet formations that orbited at a similar altitude and inclination. Formation was set up Feb 24 after one month of phasing manoeuvres.

epoch (UTC)         
s-m axis
( km )
ecc    perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Jan 29, 09:3474710.000210921095107.1263.40258
2021 Feb 01, 10:4074580.001210711088106.8263.41265
2021 Feb 19, 11:1874670.001010811096107.0263.41295
2021 Mar 03, 14:0774680.000910831097107.0563.41283


2021-014
CZ 4C
Jiuquan Space Centre
2021 Feb 24, 02:22
Yaogan 31-03 Trailer
2021-014A
47691
in space
Remote sensing satellite described as used for electromagnetic environment surveys and other related technology tests. Orbiting in close formation with the other two satellites from the launch, its purpose may be signals or electronic intelligence gathering over the world's oceans, a similar task to the US NOSS triplet formations that orbited at a similar altitude and inclination. This object was originally catalogued as 47692/2021-014B, Space-Track switched designations more than one week after launch.

epoch (UTC)         
s-m axis
( km )
ecc    perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Feb 24, 12:3074720.000610901099107.1463.41271
2021 Feb 27, 08:4474640.001310771096106.9763.41219
2021 Mar 26, 07:2374680.001010821098107.0563.41304
Yaogan 31-03 Outlier
2021-014C
47693
in space
Remote sensing satellite described as used for electromagnetic environment surveys and other related technology tests. Orbiting in close formation with the other two satellites from the launch, its purpose may be signals or electronic intelligence gathering over the world's oceans, a similar task to the US NOSS triplet formations that orbited at a similar altitude and inclination.

epoch (UTC)         
s-m axis
( km )
ecc    perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Feb 24, 14:1774720.000610901098107.1363.41267
2021 Feb 27, 03:0474910.001411021123107.5463.41257
2021 Mar 25, 12:1574720.001110851101107.1263.41285
Yaogan 31-03 Leader
2021-014E
47695
in space
Remote sensing satellite described as used for electromagnetic environment surveys and other related technology tests. Orbiting in close formation with the other two satellites from the launch, its purpose may be signals or electronic intelligence gathering over the world's oceans, a similar task to the US NOSS triplet formations that orbited at a similar altitude and inclination.

epoch (UTC)         
s-m axis
( km )
ecc    perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Feb 24, 12:3074710.000510891097107.1263.41278
2021 Feb 25, 04:3474690.000710861096107.0763.41280
2021 Feb 26, 07:1974630.000810791092106.9563.41257
2021 Mar 26, 07:2374680.001010821098107.0563.41303


2021-037
CZ 4C
Jiuquan Space Centre
2021 Apr 30, 07:27
Yaogan 34-01
2021-037A
48340
in space
Intelligence gahering satellite. Orbit is similar to the Yaogan 31 electronic surveillance satellites,and the Initial orbit plane has RAAN about three degrees to the east of that of the second Yaogan 31 triplet (launch no 2021-007). 2021 May 8, Yaogan settled into formation with Yaogan 31 Group 2, sitting 34° of orbit arc behind and following a near-identical ground track.

epoch (UTC)         
s-m axis
( km )
ecc    perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Apr 30, 12:1574720.000210931096107.1463.41305
2021 May 01, 06:0674670.000710841095107.0363.41239
2021 May 01, 09:4074630.001310761095106.9463.41264
2021 May 01, 13:1474630.001010771092106.9363.40278
2021 May 07, 06:2774680.000910831097107.0463.40327


2022-027
CZ 4C
Jiuquan Space Centre
2022 Mar 17, 07:09
Yaogan 34-02
2022-027A
52084
in space
Intelligence gathering satellite. Orbit is similar to the Yaogan 31 electronic surveillance satellites,and the Initial orbit plane has RAAN about three degrees to the east of that of the third Yaogan 31 triplet (launch no 2021-014). Settled into formation with Yaogan 31 Group 2, sitting 34° of orbit arc behind it and following a near-identical ground track.

epoch (UTC)         
s-m axis
( km )
ecc    perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2022 Mar 17, 12:2374720.000310921096107.1463.40262
2022 Mar 18, 11:2874620.001410741094106.9263.39263



Page Date - 2022 Mar 17
Updated 2022 - Mar 18

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