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#40
by
Phillip Clark
on 26 Dec, 2008 09:17
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Yaogan 5/Jianbing-7 1 reached its 94.44 minutes, 488-495 km operating orbit on December 20th. The same operational orbital period was used by the three Ziyuan-2/Jianbing-3 satellites, although there were very minor differences in their orbital eccentricities which resulted in the apogee and perigees being a few km different.
I have been looking into the possible repeating orbit patterns fo this orbital altitude and there are three possibilities, since the satellites operate in a 94.42-94.44 minutes orbit, with periodic orbital manoeuvres back to the higher period:
94.42 minutes - 442 circuits (29 days)
94.43 minutes - 381 circuits (25 days)
94.44 minutes - 320 circuits (21 days)
It isn't possible to be dogmatic and say which pattern is actually intended for these satellites because a small change in the orbital period will change the repeating pattern.
I believe that it is clear that the manoevres which I mentioned earlier for the last Jianbing-3 satellite were times to have cleared this orbital regime before the flight of what appears to be a second-generation digital photoreconnaissance satellite.
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#41
by
Liss
on 07 Jan, 2009 13:38
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BTW, has anyone seen a photograph or description of the CAST-2000 platform which apprently JB-6/Yaogans 2 and 4 use?
Phillip, try
http://www.cast.cn/uploadfiles/casten/product/book1.swf for images and some data on TTS-1/Phoenix Eye-1, TTS-2/Phoenix Eye-2, DJS-1/DFH-3, DHF-3A, DJS-2/DFH-4, CAST-968, CAST-2000, CAST-Mini and FSW buses.
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#42
by
Liss
on 07 Jan, 2009 13:43
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The payload fairing is of the type used on the CZ-4C. I haven't seen it used on a 4B before - this could support my theory that this was a 4C not a 4B.
In fact, launch vehicles for ZY-2-03 (2004) and YG-5 (2008) did have the same payload fairing. At least photos talk me this.
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#43
by
Liss
on 07 Jan, 2009 22:21
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Yaogan 5/Jianbing-7 1 reached its 94.44 minutes, 488-495 km operating orbit on December 20th.
I have been looking into the possible repeating orbit patterns fo this orbital altitude and there are three possibilities, since the satellites operate in a 94.42-94.44 minutes orbit, with periodic orbital manoeuvres back to the higher period:
94.42 minutes - 442 circuits (29 days)
94.43 minutes - 381 circuits (25 days)
94.44 minutes - 320 circuits (21 days)
It isn't possible to be dogmatic and say which pattern is actually intended for these satellites because a small change in the orbital period will change the repeating pattern.
Well, my understanding is that the actual nodal period ZY-2 satellites used was very close to 94.50 minutes with variations of only 2 seconds and 1.5 km in height. And 94.50 minutes is exactly 320 orbits in 21 days.
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#44
by
Phillip Clark
on 08 Jan, 2009 04:27
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Well, my understanding is that the actual nodal period ZY-2 satellites used was very close to 94.50 minutes with variations of only 2 seconds and 1.5 km in height. And 94.50 minutes is exactly 320 orbits in 21 days.
Sorry Igor, but while these satellites were operating the anomalistic orbtal periods were 94.44/94.45 minutes, decay to 94.41 minutes (occasionally 94.39 minutes) and then boosted back to ~94.45 minutes. Stayed that way throughout the Jianbing-3/Ziyuan-2 lifetimes.
And many thanks for the link to the CAST page with the satellite platform data. Very interesting information - which that the launch masses were given in all cases, rather than the payload packages which can be supported by the platforms.
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#45
by
Liss
on 10 Jan, 2009 15:34
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Well, my understanding is that the actual nodal period ZY-2 satellites used was very close to 94.50 minutes with variations of only 2 seconds and 1.5 km in height. And 94.50 minutes is exactly 320 orbits in 21 days.
Sorry Igor, but while these satellites were operating the anomalistic orbtal periods were 94.44/94.45 minutes, decay to 94.41 minutes (occasionally 94.39 minutes) and then boosted back to ~94.45 minutes. Stayed that way throughout the Jianbing-3/Ziyuan-2 lifetimes.
I do not want to be dogmatic as well but you probably refer to the period defined as 1440 / (mean motion figure from TLE). I refer to actual nodal period obtained by propagating an elset for one orbit and calculating times of two consecutive equartor crossings. And, by chance, 320 orbits of this 94.50 min period is exactly 21 days.
Glad to hear you've liked the platforms book.
By the way, putting aside the question wether Yaogan Weixing 3 was Jianbing 7 or not, what do you think of Yaogan Weixing 5 being Jianbing 8?
I stepped down from my earlier understanding that YG-5 is JB-7 because the latter has been described as something alike JB-5 and made by SAST. And we know now that YG-5 was made by CAST and it is obviously not a SAR bird.
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#46
by
blackjack
on 19 Jan, 2009 23:54
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I still don't think YG series have much military applications. I think the images got from those satellites were still low resolution and have little military value. One Chinese scientist said that China's remote sensing technology was still behind India last year. And according to the white paper published by CNSA in 2006, China was going to develop high resolution earth observation satellites in this five years plan. This is only the second year of this five years plan, I don't think those satellites can be developped that quickly.
It's a way to get fundings from government such as NASA did. NASA would say the technolgy of China would go beyond States when they wanted to get fundings from US government. As I seen the anylasis of public news from a technological Chinese website(
www.9ifly.cn), the resolution of YG5 is about 0.7m-0.8m.
Here is the discussion if you can understand Chinese.
http://www.9ifly.cn/sub/viewthread.php?tid=355&extra=&page=1
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#47
by
hesidu
on 24 Jan, 2009 11:04
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I don't think informantion from Chinese forums are reliable. Since most of Chinese space programs are highly confidential. So I don't think ordinary Chinese know much about the truth.
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#48
by
blackjack
on 24 Jan, 2009 19:53
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I don't think informantion from Chinese forums are reliable. Since most of Chinese space programs are highly confidential. So I don't think ordinary Chinese know much about the truth.
You have to judge the information from forums by yourself. Some comments in the forum I pointed out are very professional, I think some of them are working in the industry.
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#49
by
Satori
on 26 Jan, 2009 21:05
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Sinodefense is giving the following military designations for the YaoGan Weixing satellites:
YG-1 - JianBing-5
YG-2 - JianBing-6
YG-3 - JianBing-7
YG-4 - JianBing-8
YG-5 - JianBing-9
It also points that YG-1, YG-3 and YG-5 are SAR radar imaging satellites and that YG-2 and YG-4 are Electro-optical satellites.
Any comments on this?
Thanks!
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#50
by
Liss
on 10 Feb, 2009 08:29
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The initial orbital data and the launch time for Yaogan 5 look very similar to those seen for the three Jianbing-3/Ziyuan-2 satellites.
By the way, Aerospace China published in the December 2008 issue the first part of an article on China's Earth Resource Satellites (in Chinese). Two B&W pictures are included, one of Ziyuan-2 satellite in orbit and another of three ZY-2s phased in orbit at 120°. (This structure did exist in late 2004 but for only 10 days or so.)
Aerospace China is accessible at
http://www.space.cetin.net.cn/docs/ht97-b.htm but only through Jan 2005.
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#51
by
Liss
on 10 Feb, 2009 08:32
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Sinodefense is giving the following military designations for the YaoGan Weixing satellites:
YG-1 - JianBing-5
YG-2 - JianBing-6
YG-3 - JianBing-7
YG-4 - JianBing-8
YG-5 - JianBing-9
It also points that YG-1, YG-3 and YG-5 are SAR radar imaging satellites and that YG-2 and YG-4 are Electro-optical satellites.
Any comments on this?
Thanks!
My understanding is as follows:
YG-1 - JianBing-5 radar
YG-2 - JianBing-6 optical
YG-3 - JianBing-5 radar
YG-4 - JianBing-6 optical
YG-5 - JianBing-8? optical
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#52
by
Satori
on 16 Aug, 2011 22:23
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#53
by
input~2
on 06 Dec, 2011 15:54
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According to USSTRATCOM, the third stage of CZ-4B re-entered to-day at 0005:00UTC +/- 1 minute over the North Pacific some 1460 km NW of Oahu after 16,906 revolutions.
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#54
by
input~2
on 28 Aug, 2014 11:45
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Yaogan-5 is predicted to reenter September 1 to 3
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#55
by
Star One
on 29 Aug, 2014 15:06
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#56
by
input~2
on 29 Aug, 2014 18:30
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Space-Track latest prediction for the reentry time:
September 1, 16:45UTC +/- 8.5 hours
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#57
by
input~2
on 31 Aug, 2014 07:30
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Space-Track latest prediction for the reentry time:
September 2, 19:32UTC +/- 24 hours
Aerospace Corp.latest prediction:
September 2, 16:47UTC +/- 21 hours
Edit as of Sept 1, 0630UTC:
Space-Track latest prediction for the reentry time:
September 2, 20:04UTC +/- 12 hours
Aerospace Corp. latest prediction:
September 3, 04:33UTC +/- 16 hours
Edit as of Sept 2, 1410UTC:
Space-Track latest prediction for the reentry time:
September 2, 20:46UTC +/- 4 hours
Aerospace Corp. latest prediction:
September 2, 20:35UTC +/- 9 hours
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#58
by
russianhalo117
on 02 Sep, 2014 23:19
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#59
by
input~2
on 03 Sep, 2014 07:43
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According to USSTRATCOM Yaogan-5 reentered on September 2 at 20:30UTC over 47S 52E (Southern Indian Ocean)