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Launches and Orbital Operations


Tyneside, UK
2025 May 16
Friday, Day 136

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Yaogan 34 - The Shadow

image


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 behaviour 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.

2018-034
CZ 4C
Jiuquan Space Centre
2018 Apr 10, 04:25
Yaogan 31-01 Leader
2018-034A
43275
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 )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2018 Apr 11, 11:5874710.0009    10861100107.1163.4138
2018 Jun 15, 00:5374680.0013    10801100107.0563.418
2021 Jan 29, 03:4774680.0099    10161164107.0563.403
2023 Feb 13, 12:5274680.0166    9661214107.0463.404
2025 Feb 24, 10:4274670.0233    9151263107.0363.406
Yaogan 31-01 Follower
2018-034B
43276
in space
One of two further payloads forming the Yaogan 31-01 mission, and flying in formation with it. May be similar to the US NOSS triplet formations that orbited at a similar altitude and inclination.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2018 Apr 11, 10:1174720.0007    10891099107.1363.4137
2018 Jun 15, 20:3074680.0013    10801100107.0563.417
2021 Jan 29, 03:4774680.0099    10161164107.0563.403
2023 Feb 13, 12:5374680.0166    9661214107.0463.414
2025 Feb 24, 12:2974670.0233    9151263107.0363.406
Yaogan 31-01 Outlier
2018-034C
43277
in space
One of two further payloads forming the Yaogan 31-01 mission, and flying in formation with it. May be similar to the US NOSS triplet formations that orbited at a similar altitude and inclination.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2018 Apr 10, 19:5474720.0008    10881100107.1363.4146
2018 Apr 13, 13:4974490.0010    10631078106.6463.41338
2018 Apr 14, 08:1474420.0019    10501077106.4863.413
2018 Apr 15, 01:1974390.0015    10501073106.4363.417
2018 May 4, 18:5674400.0018    10481075106.4363.414
2018 May 5, 00:2774460.0014    10581078106.5763.4130
2018 May 7, 05:3674590.0015    10691092106.8463.4032
2018 May 8, 01:1674650.0013    10771096106.9863.41353
2018 May 11, 04:0774680.0011    10821098107.0563.418
2021 Jan 29, 03:4774680.0099    10161164107.0563.413
2023 Feb 13, 12:5374680.0166    9661214107.0463.414
2025 Feb 24, 12:2974670.0233    9151263107.0363.406
Weina 1B
2018-034E
43279
in space
Small satellite - mission unknown.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2018 Apr 16, 00:5174700.0010    10851100107.1063.4136


2021-007
CZ 4C
Jiuquan Space Centre
2021 Jan 29, 04:47
Yaogan 31-02 Outlier
2021-007A
47532
in space
One of two further payloads forming the Yaogan 31-02 mission, and flying in formation with it. May be similar to the US NOSS triplet formations that orbited at a similar altitude and inclination.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Jan 29, 22:0474720.0004    10911097107.1363.41274
2021 Feb 2, 10:4874930.0010    11081123107.5963.41261
2021 Feb 21, 02:5174860.0008    11021114107.4363.40261
2021 Feb 22, 07:0474770.0003    10961101107.2363.4139
2021 Feb 25, 10:0274680.0009    10831097107.0563.41282
2021 Mar 3, 08:4674680.0009    10831097107.0563.41284
2023 Feb 13, 12:2074680.0067    10401140107.0463.41353
2025 Feb 24, 10:1274670.0134    9901189107.0363.40359
Yaogan 31-02 Folower
2021-007B
47533
in space
One of two further payloads forming the Yaogan 31-02 mission, and flying in formation with it. May be similar to the US NOSS triplet formations that orbited at a similar altitude and inclination.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Jan 30, 01:3974720.0005    10911098107.1463.41276
2021 Feb 2, 10:3174580.0012    10711088106.8363.41348
2021 Feb 23, 04:3174680.0009    10831096107.0463.41283
2021 Feb 28, 16:3274680.0009    10831097107.0563.41284
2023 Feb 13, 12:2074680.0067    10401140107.0463.41353
2025 Feb 24, 10:1274670.0134    9891189107.0363.40359
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 )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Jan 29, 09:3474710.0002    10921095107.1263.40258
2021 Feb 1, 10:4074580.0012    10711088106.8263.41265
2021 Feb 19, 11:1874670.0010    10811096107.0263.41295
2021 Mar 3, 14:0774680.0009    10831097107.0563.41283
2023 Feb 13, 12:2074680.0067    10401140107.0463.41353
2025 Feb 24, 10:1274670.0134    9891189107.0363.40359


2021-014
CZ 4C
Jiuquan Space Centre
2021 Feb 24, 02:22
Yaogan 31-03 Follower
2021-014A
47691
in space
One of two further payloads forming the Yaogan 31-03 mission, and flying in formation with it. May be similar to the US NOSS triplet formations that orbited at a similar altitude and inclination.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Feb 24, 12:3074720.0006    10901099107.1463.41271
2021 Feb 27, 08:4474640.0013    10771096106.9763.41219
2021 Mar 26, 07:2374680.0010    10821098107.0563.41304
2023 Feb 13, 13:2874680.0068    10391140107.0463.41354
2025 Feb 24, 13:0774670.0135    9891190107.0363.41359
Yaogan 31-03 Outlier
2021-014C
47693
in space
One of two further payloads forming the Yaogan 31-03 mission, and flying in formation with it. May be similar to the US NOSS triplet formations that orbited at a similar altitude and inclination.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Feb 24, 14:1774720.0006    10901098107.1363.41267
2021 Feb 27, 03:0474910.0014    11021123107.5463.41257
2021 Mar 25, 12:1574720.0011    10851101107.1263.41285
2023 Feb 13, 13:2874680.0068    10391140107.0463.41354
2025 Feb 24, 13:0774670.0135    9881190107.0363.41359
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 )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Feb 24, 12:3074710.0005    10891097107.1263.41278
2021 Feb 25, 04:3474690.0007    10861096107.0763.41280
2021 Feb 26, 07:1974630.0008    10791092106.9563.41257
2021 Mar 26, 07:2374680.0010    10821098107.0563.41303
2023 Feb 13, 13:2774680.0068    10391140107.0463.41354
2025 Feb 24, 13:0774670.0135    9891190107.0363.41359


2021-020
CZ 4C
Jiuquan Space Centre
2021 Mar 13, 02:19
Yaogan 31-04 Leader
2021-020A
47854
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. Until 2021 Apr 8, this satellite was catalogued as 2021-020B/47855 - that ID now belongs to an item of debris.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Mar 13, 14:1474710.0003    10901096107.1163.41297
2021 Mar 18, 06:4074670.0009    10821095107.0263.41286
2021 Apr 8, 14:3574680.0009    10831097107.0563.41300
2023 Feb 13, 13:1974680.0066    10411139107.0463.41354
2025 Feb 24, 11:1074670.0133    9901188107.0363.41359
Yaogan 31-04 Outlier
2021-020C
47856
in space
One of two further payloads forming the Yaogan 31-04 mission, and flying in formation with it. May be similar to the US NOSS triplet formations that orbited at a similar altitude and inclination.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Mar 13, 17:4874720.0004    10911097107.1363.41282
2021 Mar 18, 05:3474960.0010    11111126107.6563.41344
2021 Apr 8, 13:2074890.0006    11061116107.5063.41296
2023 Feb 13, 04:2474680.0065    10411139107.0463.41354
2025 Feb 24, 12:5874670.0132    9901188107.0363.41359
Yaogan 31-04 Follower
2021-020D
47857
in space
One of two further payloads forming the Yaogan 31-04 mission, and flying in formation with it. May be similar to the US NOSS triplet formations that orbited at a similar altitude and inclination.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Mar 14, 11:4074720.0004    10911097107.1363.41279
2021 Mar 19, 07:4274660.0009    10811095107.0063.41286
2021 Apr 10, 04:0374680.0010    10831097107.0563.41302
2023 Feb 13, 13:1974680.0065    10411139107.0463.41354
2025 Feb 24, 11:1174670.0132    9901188107.0363.41359


2021-037
CZ 4C
Jiuquan Space Centre
2021 Apr 30, 07:27
Yaogan 34-01
2021-037A
48340
in space
Imaging 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 )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2021 Apr 30, 12:1574720.0002    10931096107.1463.41305
2021 May 1, 06:0674670.0007    10841095107.0363.41239
2021 May 1, 09:4074630.0013    10761095106.9463.41264
2021 May 1, 13:1474630.0010    10771092106.9363.40278
2021 May 7, 06:2774680.0009    10831097107.0463.40327
2023 Feb 13, 05:2374680.0065    10411138107.0463.41356


2022-027
CZ 4C
Jiuquan Space Centre
2022 Mar 17, 07:09
Yaogan 34-02
2022-027A
52084
in space
Imaging 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 3, sitting 34° of orbit arc behind it and following a near-identical ground track.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2022 Mar 17, 12:2374720.0003    10921096107.1463.40262
2022 Mar 18, 11:2874620.0014    10741094106.9263.39263
2023 Feb 13, 08:1674680.0026    10701109107.0463.40345


2022-154
CZ 4C
Xichang Space Centre
2022 Nov 15, 01:38
Yaogan 34-03
2022-154A
54249
in space
Imaging 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 fourth Yaogan 31 triplet (launch no 2021-020). Expected to move into formation with the Yaogan 31 group.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2022 Nov 15, 14:2674730.0003    10921097107.1463.41272
2022 Nov 17, 20:5174620.0009    10771091106.9263.41251


2023-048
CZ 4C
Jiuquan Space Centre
2023 Mar 31, 06:27
Yaogan 34-04
2023-048A
56157
in space
Imaging 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 first Yaogan 31 triplet (launch no 2018-034). Expected to move into formation with the Yaogan 31 group.

epoch (UTC)         
s-m axis
( km )

eccentricity
perigee
( km )
apogee
( km )
period
( min )
incl 
( ° )
ω  
( ° )
2023 Mar 31, 10:0574720.0003    10921096107.1463.40257
2023 Apr 1, 09:0774730.0002    10941097107.1663.40277
2023 Apr 15, 14:1574700.0007    10871097107.0963.40307



Page Date - 2022 Mar 17
Updated 2022 - Mar 18

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