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China to Have Over 100 Eyes in the Sky
gollum123 writes "Reuters reports China plans to launch more than 100 satellites before 2020 to watch every corner of the country, state-run China Central Television quoted a government official as saying Tuesday. A "large surveying network" would be set up to monitor water reserves, forests, farmland, city construction and "various activities of society," a government official said without elaborating. "The aim is that, at any time and any place, we can obtain necessary data on any event through watching the Earth from space," said Shao Liqin, an official with the Ministry of Science and Technology."
Hey, they are not the only ones using satellite pictures for various other tasks. Maybe their purpose is the same as some US activities:
0 4-09-26-civilian-spying_x.htm
http://www.usatoday.com/tech/news/surveillance/20
AFAIK, the vast majority of spy satellites are also in rather low orbit for a variety of economic and plain rational reasons. 100 satellites should be more than enough for China to constantly keep monitored areas of their country in view even if half of them are on the other side of Earth. Plus this offers the ability to see in different angles, while geosynchronous orbit would only offer a narrow angle.
And if the satellites occasionally fly over other countries, who are the Chinese to complain?
What strikes me as strange with this is that the information about this was actually released. They don't even bother hiding that they are spying on all and everything.
What's the status on those home-made satellite jammers again?
All rites reversed 2010
Things like this have been flying for decades.
I'd like to know what sort of sensors and resolutions will be flying and what they plan to charge for raw data.
Now I'm the grandest Tiger in the Jungle!
The other issue at hand here is cost: the average life span of a spy satellite is about 3.5 or 4 years. The optics start to fog over due to radiation from the sun, and on something as precise as a spy satellite, that's a big deal. Plus space junk ... my bet is that China launches 4 spy satellites in useless orbits by 2020 then gives up because it's just too darned expensive.
The maintenance on that kind of system would just be too darned expensive. Any GPS experts out there to lend credibility to this?
"Diplomacy is something you do until you find a rock." --Richard Pound
http://service.china.org.cn/link/wcm/Show_Text?inf o_id=112464
Highlights:
Sun Laiyan, director of the China National Space Administration (CNSA), said that a large satellite-based earth observation system will also be built by 2010. The system could be used for observation of land, atmosphere and ocean within China, its adjacent areas and even the entire globe.
Sun said that China will develop a new generation of polar orbit and stationary orbit meteorological satellites, high-performance resource follow-up satellites, oceanic color and dynamic observation satellites.
All rites reversed 2010
With a resolution of 5cm (2 inches) or 10cm (4 inches), the spy satellites can certainly track people. Source: Resolution of a Spy Satellite.
Note that a satellite does not have to be able to recognize your face to track you (it is hard to see it from the sky anyway). You can be identified by many other details.
-Raphaël
Remember that a geosynchronous orbit is restricted to the equator, for reasons which are obvious if you think about them. (It's not just a matter of travelling at the same speed as the ground beneath you; you also need to be travelling in the same direction and around the Earth's centre of mass.)
So, if these sats really are primarily for internal surveillance, anything "over areas of significant interest" probably isn't going to be geosync. Unless you're really into rainforests, most of the equator isn't that interesting.
...We have camera's on the ground (lots and lots of them)
I live in the UK.
That's the resolution for a top-of-the-line KH-12 Keyhole-class satellite operated by the United States, which cost approximately $1 billion each. Even if the Chinese had the technical ability to produce such a thing, which they haven't even come close to demonstrating, they barely have the resources to put up one such satellite, let alone 100. Realistically, it's far more likely that in order to create such a network, the resolving power they'll wind up with will be comparable to western commercial satellites, on the order of 1-10 meters at best.
ABSURDITY, n.: A statement or belief manifestly inconsistent with one's own opinion.
That's a lot of extra spending.
Spatial resolution on the ground is directly proportional to the diameter of the aperture (primary lens or mirror) and inversely proportional to altitude.
By going from a low to middling earth orbit at 500 to 1000 kilometers, to geosynchronous orbit at 36000 km, you need to increase the size of your aperture by a factor of between about thirty and seventy. To replicate the resolution performance of a 1' (30 cm) mirror in low earth orbit takes a mirror 30' to 70' (about twenty meters) across in geosynchronous orbit. That's twice the diameter of the Keck telescopes on Mauna Kea, three times the diameter of the as-yet-unlaunched James Webb Space Telescope, and eight times the diameter of Hubble. (My back-of-the-envelope number is a resolution of a little better than one meter with those mirrors).
Also, putting stuff into geosynchronous orbit is significantly more difficult than putting stuff in low earth orbit. (For commercial launches, lofting a payload to geosynchronous transfer orbit sets you back about three times as much on a per pound basis.)
The physics and economics strongly argue for many satellites in lower orbits. There's the added benefit of being able to spy on other countries, too. The Chinese government doesn't need satellites to spy on its own people--it can do that with human intelligence (spies), ground-based cameras, and aircraft/drone surveillance.
~Idarubicin
HST has been in LEO for how long?
The optics are generally reflective, rather than transmissive, and while they might suffer micrometeoroid dings, they can last quite a long time. Spy telescopes also don't need to be as precise as astronomical telescopes, since they're looking back through the atmosphere, which fuzzes out things on the ground.
Earth observing sats commonly have a design lifetime of 3-5 years, but also commonly are expected by their users to last closer to 10, as long as they don't rely on consumables (cryogens or propellant) to do their jobs.
I do agree that GEO is probably too far, especially considering they probably don't have capability to make very large optics that would be needed. A polar orbit is much more likely, and for that you probably need quite a lot less than a hundred -- Iridium flies low and gets good coverage with 66 sats (I know, it's RF, but they are counting on being more or less overhead, rather than just somewhere above the horizon like GPS, which has 24 sats).
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