Author Topic: Jianbing Radar Satellites' Orbits  (Read 851 times)

Offline Phillip Clark

  • Senior Member
  • *****
  • Posts: 2246
  • Hastings, England
  • Liked: 330
  • Likes Given: 838
Jianbing Radar Satellites' Orbits
« on: 02/20/2018 06:25 PM »
I came across something which looks interesting while preparing a series of Excel graphs relating to the various series of Jianbing satellites.

Yaogan Weixings 1, 3 and 10 form the JB-5 radar series of satellites and it appears that this series has been replaced by a series which I call JB-X2 (since we do not know the actual JB number as far as I am aware) which comprises the single Yaogan Weixing 29 satellite.

I am attaching a document which shows graphs of the arguments of perigees of these two series, and it clear that they are being "controlled" to be close to 90 degrees.   This cannot be natural evolution, the AoP remains stationary only for satellites in orbits with inclinations close to 63.4 degrees.

There is no similar behaviour for the Jianbing-7 radar satellites and I have not seen anything similar for the optical reconnaissance satellites (yet, anyway!).
I've always been crazy but it's kept me from going insane - WJ.

Offline Liss

  • Full Member
  • ****
  • Posts: 999
  • Moscow, Russia
  • Liked: 178
  • Likes Given: 8
Re: Jianbing Radar Satellites' Orbits
« Reply #1 on: 02/21/2018 06:35 AM »
I came across something which looks interesting while preparing a series of Excel graphs relating to the various series of Jianbing satellites.

Yaogan Weixings 1, 3 and 10 form the JB-5 radar series of satellites and it appears that this series has been replaced by a series which I call JB-X2 (since we do not know the actual JB number as far as I am aware) which comprises the single Yaogan Weixing 29 satellite.

I am attaching a document which shows graphs of the arguments of perigees of these two series, and it clear that they are being "controlled" to be close to 90 degrees.   This cannot be natural evolution, the AoP remains stationary only for satellites in orbits with inclinations close to 63.4 degrees.

Phillip,
For YG-29 apogee and perigee calculated from TLEs differ only by 2 kilometers.
I doubt very much the graph of AoP for this spacecraft shows some real effect -- my guess this is an artifact of algorythms involved in preparing TLEs.
This message reflects my personal opinion based on open sources of information.

Offline Phillip Clark

  • Senior Member
  • *****
  • Posts: 2246
  • Hastings, England
  • Liked: 330
  • Likes Given: 838
Re: Jianbing Radar Satellites' Orbits
« Reply #2 on: 02/21/2018 08:49 AM »
Thank you for your thoughts Igor.   I have often seen the TLEs for objects which are in extremely circular orbits and normally the arguments of perigee can have random values because it is so difficult the accurately pin-point where perigee is actually located.   I cannot remember having come across this particular result from modelling the TLEs before, although of course that is not to say it is what is happening!

When I started to get the paper TLEs in August 1980 of course all of the processing had to be done by hand (well, by TI-59 - still my all-time favourite calculator!) and so I was seeing what individual TLEs were like.   Then starting in 1994 everything went digital and since then all of the data are in digital archives with all of the orbital calculations done using software originally written by Peter Hunter and since then heavily modified and expanded by myself.   Now, I no longer "get down and dirtly" with the TLEs!   Of course, in those days it would be nearly impossible to process the number of TLEs which are available these days in their paper format.

Just reminiscing ..........
I've always been crazy but it's kept me from going insane - WJ.

Online Alter Sachse

  • Full Member
  • ****
  • Posts: 672
  • Germany
  • Liked: 115
  • Likes Given: 219
Re: Jianbing Radar Satellites' Orbits
« Reply #3 on: 02/22/2018 05:54 PM »
Yaogan launch times:
No.1  22:48:11
No.3  22:48:14.843
No.10 22:49:05.551
No.29 21:24:04.681



Offline Steven Pietrobon

  • Member
  • Senior Member
  • *****
  • Posts: 15388
  • Adelaide, Australia
    • Steven Pietrobon's Space Archive
  • Liked: 4690
  • Likes Given: 606
Re: Jianbing Radar Satellites' Orbits
« Reply #4 on: 02/23/2018 06:44 AM »
Yaogan launch times:
No.1  22:48:11
No.3  22:48:14.843
No.10 22:49:05.551
No.29 21:24:04.681

Using YG 1 as a reference, the difference in times (to the nearest second) are

YG 3   00:00:03
YG 10  00:00:55
YG 29 -01:24:06


So, YG 1, 3 and 10 look to be in the same sun synchronous plane, while YG 29 is in a plane that crosses one hour and 24 minutes earlier. This is roughly also the time that it takes the first satellites to do one orbit. Not sure if that means anything.
« Last Edit: 02/23/2018 06:44 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Liss

  • Full Member
  • ****
  • Posts: 999
  • Moscow, Russia
  • Liked: 178
  • Likes Given: 8
Re: Jianbing Radar Satellites' Orbits
« Reply #5 on: 02/23/2018 07:55 AM »
So, YG 1, 3 and 10 look to be in the same sun synchronous plane, while YG 29 is in a plane that crosses one hour and 24 minutes earlier. This is roughly also the time that it takes the first satellites to do one orbit. Not sure if that means anything.

Steven, the launch times show only that initial planes of the three JB-5 satellites were the same, namely of 06:00 LTDN.
You should check if this parameter is controlled in a particular constellation or not. For JB-5, it is not controlled and the maximum deviation is of the order of one hour (15 degrees in RAAN). In a sense, the three JB-5s has never worked in one plane.

« Last Edit: 02/23/2018 07:59 AM by Liss »
This message reflects my personal opinion based on open sources of information.

Tags: