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#40
by
Zannanza
on 04 Sep, 2013 13:12
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Just curious. CZ-4C has a fairing diameter of 3.35m and a payload capacity of approx. 4mT to LEO, this will give an average of 1.33mT per satellite. This is much smaller than typical radar and optical spy satellites launched by the US or even Japan and Europe, which typically require medium to heavy EELVs to put just one into orbit. Can anyone tell me what kind of spy satellites can be accommodated by a 1,000kg-class satellite bus? Thanks.
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#41
by
Skyrocket
on 04 Sep, 2013 13:34
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Just curious. CZ-4C has a fairing diameter of 3.35m and a payload capacity of approx. 4mT to LEO, this will give an average of 1.33mT per satellite. This is much smaller than typical radar and optical spy satellites launched by the US or even Japan and Europe, which typically require medium to heavy EELVs to put just one into orbit. Can anyone tell me what kind of spy satellites can be accommodated by a 1,000kg-class satellite bus? Thanks.
The spacecraft mass gives not much information on the type of spacecraft. For example, the German SAR-Lupe radar spy sats (1 m resolution) have only a weight of just 770 kg (
http://space.skyrocket.de/doc_sdat/sar-lupe.htm) and the Israeli Ofeq optical spysats (~0.5 m resolution) have masses of about 300 kg (
http://space.skyrocket.de/doc_sdat/ofeq-3.htm)
In the case of YG 17, the payload is an ELINT payload. Also a 2.9 m diameter fairing was used, not a 3.35 m one.
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#42
by
jcm
on 04 Sep, 2013 22:39
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Very interesting Japanese news story from china xinhua.
They watched here 
NASASpaceFlight was reported successfully launched (remote sensing) satellite.
This article pointed out that the satellite sees ocean surveillance satellite with military applications.
In response to an interview with Global Times, military expert of China are aimed at people for marine traffic and safety. Land surveying, disaster prevention mitigation for the launch of remote-sensing satellite to help economic construction of the country. U.S. is always criticizing other countries, but they has been the launch of secret frequently.
http://www.xinhua.jp/socioeconomy/photonews/358563/
Thanks Fuji.
I think the first sentence should translate as
NASASpaceFlight was reported successfully launched Yaogan-17 satellite.
Or, in English,
NASASpaceFlight reported the successful launch of the Yaogan-17 satellite.
:-)
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#43
by
JimO
on 05 Sep, 2013 04:04
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I've done a freehand sketch of the rev 0 ground track, which shows the Melbourne flyover an hour before sunrise. But now with the TLEs out could somebody please run off and post a graphic of that ground track?
In further work to elucidate the nature of the several white dots seen by multiple Melbourne observers, does anyone have any reference data on the nominal payload ejection times?
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#44
by
der Architekt
on 05 Sep, 2013 07:21
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YG series is indeed military satellites
There exist Chinese publications that suggest YG series might be used to triangulate and detect locations of aircraft carrier groups and relay the info to PLA's ballistic anti-ship missile facility
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#45
by
Liss
on 05 Sep, 2013 07:43
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In the 2010 launch, the track did pass over Melbourne as seen in images.
My calculations then gave third stage deorbit fire at 31 min after the launch.
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#46
by
input~2
on 05 Sep, 2013 11:35
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I've done a freehand sketch of the rev 0 ground track, which shows the Melbourne flyover an hour before sunrise. But now with the TLEs out could somebody please run off and post a graphic of that ground track?
In further work to elucidate the nature of the several white dots seen by multiple Melbourne observers, does anyone have any reference data on the nominal payload ejection times?
Here is a portion of the first orbit of Object-D (using the first published tle, epoch 2028UTC, and Orbitron). The object was overhead Melbourne at 1948UTC corresponding to the sighting time.
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#47
by
JimO
on 05 Sep, 2013 11:58
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Can we combine these two VERY helpful responses and conclude the stage was doing its burn WHILE in sight of Melbourne. Could that be what the video is showing? How long was the burn?
ADD: I'm guessing that an analysis of the booster post-burn orbit parameters would allow calculation of the interval during which the orbit lowering burn occurred, right?
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#48
by
JimO
on 05 Sep, 2013 16:03
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Very nice, this nails down the stimulus...
Igor Lissov has pointed out that the last stage orbit lowering burn
on the previous triplet occurred at L + 31 minutes, so the question arises,
were these guys seeing the rocket burn, the post burn dump, or both?
One could compute the burn event time by tracking back the booster's TLE.
And if we can estimate delta-V we can estimate burn duration.
Alternately, there may be no 'burn', no actual engine ignition, since the post-deploy orbit lowering may be performed BY the fuel dump itself. Just speculating.
Ted Molczan's solution to the sighting:
Video of Yaogan 17 rocket fuel dump // Thu Sep 05 2013 - 14:23:27 UTC
http://satobs.org/seesat/Sep-2013/0067.html
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#49
by
JimO
on 05 Sep, 2013 19:18
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We won't be getting any more help from the guy in Melbourne who made the original videotape. He's just deleted all the comments that argue his 'UFO' was the Chinese launch, with the statement:
"Lou20764 31 minutes ago -- Not putting up with a organized attack by trolls anymore - I just took out the garbage and I feel good about it. If some of you want to belive this was a Chinese rocket - Fine."
Sad, but not unusual.
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#50
by
JimO
on 05 Sep, 2013 21:33
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How can we check contacts in Oz to ask about any local media coverage in the last few days that may have reported, or offered explanations for, the Melbourne sighting -- or was it just not all that impressive? Thanks!
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#51
by
Targeteer
on 06 Sep, 2013 01:01
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#52
by
Targeteer
on 07 Sep, 2013 03:00
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#53
by
input~2
on 07 Sep, 2013 19:30
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USSTRATCOM has now identified the 6 objects as:
A: Yaogan-17A
B: Yaogan-17B
C: Yaogan-17C
D: Rocket body (CZ-4C R/B)
E & F: CZ-4C debris
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#54
by
jcm
on 07 Sep, 2013 23:53
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USSTRATCOM has now identified the 6 objects as:
A: Yaogan-17A
B: Yaogan-17B
C: Yaogan-17C
D: Rocket body (CZ-4C R/B)
E & F: CZ-4C debris
but be careful, they also switched the identities of the pieces today.
C is what used to be F and B is what used to be E, I think
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#55
by
JimO
on 08 Sep, 2013 19:42
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Any official Chinese release of elements, including inclination and orbital period?
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#56
by
beidou
on 08 Sep, 2013 19:57
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Not yet, and we shouldn't expect one.
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#57
by
Galactic Penguin SST
on 09 Sep, 2013 00:39
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Any official Chinese release of elements, including inclination and orbital period?
They sometimes don't even do that for Shenzhou missions, so nope.
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#58
by
fatjohn1408
on 10 Sep, 2013 16:24
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Are these satellites still developped and operated by CAST? I can find no source of that but previous versions of Yaogan were.
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#59
by
limen4
on 11 Sep, 2013 07:16
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Are these satellites still developped and operated by CAST? I can find no source of that but previous versions of Yaogan were.
The triple-sat Yaogan are based on the CAST-2000 (former CAST-968) platform. The first satellites of this type have been built in Beijing but the production of microsatellites was later transfered to the Shenzhen based Aerospace Dongfanghong Satellite Company which is a CAST subsidary. The operator of the Yaogan satellites is very likely the PLA General Staff Department but this is only a guess.
