Jura The idiot
General
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Satellites in orbit 22
China's Space Program News Thread
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Satellites in orbit 22
The reason why I ask is because SCMP seems to imply there were more than 20 before this launch, which means there should be more than 22 right now. See article below:
But then again they only used the term 'in orbit' instead of 'active'.
Hendrik_2000
Lieutenant General
From Henri K blog about the Yaogan 30 series 2. Sometime ago someone question Henri K knowledge about Rocket and space technology Reading his analysis he know more and most of us here
His analysis show this new constellation of satellite is intended for high revisit rate of 22 minute per visit. His conclusion it is optical satellite for almost constant surveillance for you know what
The mysterious constellation Yaogan-30
On November 24, 2017, a Chinese rocket type CZ-2C a trio of spy satellites. They received the name of Yaogan-30-02, and the chosen orbit was inclined 35 °, with an altitude of 600km.
The Yaogan-30-01 trio
Although China is showing some form of openness about its military launches, the true nature of the Yaogan-30 satellites remains unclear. They are a relatively recent addition to . A first trio of the same type was previously launched on September 29, 2017, under the name Yaogan-30-01. Officially, the purpose of these satellites is to " ", which is a euphemism for wiretapping.
This is consistent with the fact that wiretapping satellites are often launched in thrice, such as the US satellites , or the Yaogan-16, -17, -20 and -25 Chinese triplets. The advantage of triplets is that satellites flying in close formation, spaced a few tens of kilometers apart, can accurately triangulate and locate the source of an electromagnetic signal. It's harder to do with just one satellite.
However, the Yaogan-30-01 satellites do not fly curiously in formation:
Yaogan-30-01 trio ground tracks
These images show that the Yaogan-30-01 trio separated, and that the satellites were placed at 120 ° from each other. As have pointed out, they are therefore too far apart to provide for the triangulation of signals, since there is not even a clear line of sight between them. On the other hand, this type of arrangement corresponds to what is expected if 3 satellites are placed so as to maximize their revisit frequency.
In addition, the altitude of the orbit is oddly low for electronic listening satellites: usually, they are placed relatively high, around 1000km altitude, to increase their field of view. Imaging satellites are placed low, however, to increase their resolution by keeping an acceptable field of view. Therefore, it is doubtful that the Yaogan-30 constellation is dedicated to wiretapping: the only indications in this sense are official images and statements, which could be misinformation. Satellites could very well be small optical satellites providing a high revisit frequency.
We can also see in the first image that thanks to their low orbital inclination, the satellites have a good coverage of the Pacific Ocean, India, China, North Korea and even Japan, but that the The most northern and southern parts of the globe are not covered: satellites spend their time in the latitude band that is of interest to China's defense.
But back to the Yaogan-30-02 trio that was launched recently:
Current footprints of Yaogan-30-01 (green) and Yaogan-30-02 (red)
3D view of Yaogan-30-01 (green) and Yaogan-30-02 (red)
Recent Yaogan-30-02 orbital data show that satellites have begun to drift relative to each other. They are already too far away to form a classic wiretap triplet. In all probability, they will continue to drift until they are 120 ° apart, as in the previous launch. This will double the frequency of revisiting the Yaogan-30 constellation. The final orbits can be represented using Marco Langbroek's tool :
This kind of constellation is starting to look very much of small satellites that are being developed in the civilian world, and have been by DARPA in the United States. Especially if we take into account the rumors of a third launch of a trio Yaogan-30. With 9 satellites, the constellation would have an extremely high revisit frequency:
With such a constellation, 19 passes per 24 hours are made for a site at the latitude of Taipei (25 ° North). And these are passes with less than 45 ° of misalignment, which means that the angle of view is relatively close to the vertical and therefore the passes are usable for an imaging satellite. If we take into account a maximum misalignment of 85 °, which remains exploitable for a satellite of wiretapping, then there are up to 54 passes per 24h, and the holes in the cover provided by the constellation last plus 22 minutes. So there is almost constant coverage.
In conclusion, China is deploying a very high frequency constellation of revisit, most likely for tactical use during military operations. Official statements indicate that this would be a wiretap constellation. If this is the case, it would provide near-continuous coverage of the region around 30 ° N. If, on the other hand, it is actually an imaging constellation, it will still provide an extremely high revisit frequency for the same regions. In any case, it will give China a significant military advantage.
His analysis show this new constellation of satellite is intended for high revisit rate of 22 minute per visit. His conclusion it is optical satellite for almost constant surveillance for you know what
The mysterious constellation Yaogan-30
On November 24, 2017, a Chinese rocket type CZ-2C a trio of spy satellites. They received the name of Yaogan-30-02, and the chosen orbit was inclined 35 °, with an altitude of 600km.
The Yaogan-30-01 trio
Although China is showing some form of openness about its military launches, the true nature of the Yaogan-30 satellites remains unclear. They are a relatively recent addition to . A first trio of the same type was previously launched on September 29, 2017, under the name Yaogan-30-01. Officially, the purpose of these satellites is to " ", which is a euphemism for wiretapping.
This is consistent with the fact that wiretapping satellites are often launched in thrice, such as the US satellites , or the Yaogan-16, -17, -20 and -25 Chinese triplets. The advantage of triplets is that satellites flying in close formation, spaced a few tens of kilometers apart, can accurately triangulate and locate the source of an electromagnetic signal. It's harder to do with just one satellite.
However, the Yaogan-30-01 satellites do not fly curiously in formation:
Yaogan-30-01 trio ground tracks
These images show that the Yaogan-30-01 trio separated, and that the satellites were placed at 120 ° from each other. As have pointed out, they are therefore too far apart to provide for the triangulation of signals, since there is not even a clear line of sight between them. On the other hand, this type of arrangement corresponds to what is expected if 3 satellites are placed so as to maximize their revisit frequency.
In addition, the altitude of the orbit is oddly low for electronic listening satellites: usually, they are placed relatively high, around 1000km altitude, to increase their field of view. Imaging satellites are placed low, however, to increase their resolution by keeping an acceptable field of view. Therefore, it is doubtful that the Yaogan-30 constellation is dedicated to wiretapping: the only indications in this sense are official images and statements, which could be misinformation. Satellites could very well be small optical satellites providing a high revisit frequency.
We can also see in the first image that thanks to their low orbital inclination, the satellites have a good coverage of the Pacific Ocean, India, China, North Korea and even Japan, but that the The most northern and southern parts of the globe are not covered: satellites spend their time in the latitude band that is of interest to China's defense.
But back to the Yaogan-30-02 trio that was launched recently:
Current footprints of Yaogan-30-01 (green) and Yaogan-30-02 (red)
3D view of Yaogan-30-01 (green) and Yaogan-30-02 (red)
Recent Yaogan-30-02 orbital data show that satellites have begun to drift relative to each other. They are already too far away to form a classic wiretap triplet. In all probability, they will continue to drift until they are 120 ° apart, as in the previous launch. This will double the frequency of revisiting the Yaogan-30 constellation. The final orbits can be represented using Marco Langbroek's tool :
This kind of constellation is starting to look very much of small satellites that are being developed in the civilian world, and have been by DARPA in the United States. Especially if we take into account the rumors of a third launch of a trio Yaogan-30. With 9 satellites, the constellation would have an extremely high revisit frequency:
With such a constellation, 19 passes per 24 hours are made for a site at the latitude of Taipei (25 ° North). And these are passes with less than 45 ° of misalignment, which means that the angle of view is relatively close to the vertical and therefore the passes are usable for an imaging satellite. If we take into account a maximum misalignment of 85 °, which remains exploitable for a satellite of wiretapping, then there are up to 54 passes per 24h, and the holes in the cover provided by the constellation last plus 22 minutes. So there is almost constant coverage.
In conclusion, China is deploying a very high frequency constellation of revisit, most likely for tactical use during military operations. Official statements indicate that this would be a wiretap constellation. If this is the case, it would provide near-continuous coverage of the region around 30 ° N. If, on the other hand, it is actually an imaging constellation, it will still provide an extremely high revisit frequency for the same regions. In any case, it will give China a significant military advantage.
I think Yaogan-30x are for wiretapping just as the government said "electromagnetic experiment". The optical job is for Jilin-xx. By 2020, Jilin satellites are to be numbered 60 providing 20 minutes revisit anywhere in the world, and 2030 to number 138 providing 10 minutes revisit. Jilin satellites can track a moving car on the ground or a recreational yacht in the sea, so no need for duplicating the job.
SinoSoldier
Colonel
The Chinese will test a 4-meter-diameter solid rocket booster during Spring Festival in 2018, in preparation for the KZ-21 and KZ-31 rockets (pictured below). Note that a 4-meter-diameter booster will be larger than the Space Shuttle's SRBs, the Ariane-5's boosters, as well as India's S200, making it the largest rocket booster ever built and a great candidate for the CZ-9 rocket program.
SinoSoldier
Colonel
Also, KZ-21 will have a max (LEO?) payload of 20 tons while the KZ-31 a payload of 70 tons. 
broadsword
Brigadier
They have lattice fins. Are their respective first stages reusable?
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