If China wanted to hush the purpose of a space launch, can it be inferred outside of China?

Question

What I had in mind is that China's territory is rather large and they could place a launch site deep within its territory. Flow of information is tightly controlled as it is with the Great Firewall of China in place, and the communist Big Brother having eyes and ears at every corner of its territory, leaving West in the cold without direct means of establishing their mission's purpose, if China chose to keep it secret.

At least any information that could be gathered via intelligence agencies of the West would likely not leak to the public (or so they would try), to avoid diplomatic repercussions. So my question actually is, how likely would any information about China's secret space missions find its way to the general public? To keep this question from being primarily opinion based, I would like you to provide examples of past missions that were launched under wraps. Who disclosed what information and when (how long after the launch) it became public knowledge? How reliable have these past reports proved to be? Are there any instances of faked reports or additional counterespionage measures to throw the West off course?

Could we infer, via remote sensing or other means of tracking the Chinese territory launch site's activity and actual rocket launches, what they're up to? E.g., could we establish what orbit would some Chinese military satellite assume, or its purpose?
Or, if the purpose of the mission was something else than orbiting a remote sensing satellite, do we have the means to analyze potential threat such missions could pose if China chose to keep it a secret?

Answer 1

Yes, there are methods to track and estimate what a payload is up to. Most methods rely on visual or radar to identify the orbit and its parameters. There are many amateurs that do this. Once an object has been located and its orbit calculated, you can then monitor changes in the orbit. Generally these things are public.

Imaging the object is generally the next step. You can see many telescopic pictures of the ISS online. This is a bit harder for the average amateur but there are a few that can do this specifically. Sometimes the images are inconclusive, but generally a guesstimate is possible. Measuring the electronic emissions from the object can also tell you what it might be doing.

The final piece of the puzzle is the rocket that launched it. This will give you a size and mass estimate (or rather an upper and lower bounds). This is generally not something that will be made public except for the launching nation.

A good example of this is the X-37B. The USAF provide some launch info, but most is left to the amateur astronomy community to discover.

EDIT:

Tools we can probably assume the big boys have:

HD Radar and images of the Sat. With the right telescopes, you can get good images of the sat. Might not tell you everything, but something that looks like a space telescope, probably is.

http://en.wikipedia.org/wiki/United_States_Space_Surveillance_Network#Ground-based_Electro-Optical_Deep_Space_Surveillance

http://en.wikipedia.org/wiki/Air_Force_Maui_Optical_and_Supercomputing_observatory

Passive Electronic Sensors. Basic things like a spectrum analyser and a directional antenna can give you its transmissions.

I don't believe there are any public releases of examples of this with regards to Chinese Sats. The best is probably the sat they destroyed a number of years ago.

Basically like all intelligence, guessing is sometimes the best we have.

Answer 2

A lot of information could be gleaned simply from determining the orbit and characterizing the type of electromagnetic radiation it emits. Getting a decent picture of the satellite would also help considerably.

For example, a GEO satellite is almost assuredly going to be used for communication or very wide field-of-view remote sensing (e.g. weather, missile warning). The longitude of its orbital slot would then help determine what geographic region it was assigned to. Over China, probably communications or weather. Over the US, perhaps not.

Coupling this information with how often at what frequency and at what power level it emits radiation (ostensibly for communications) would help further identify the mission. GEO communication satellites, like those that broadcast TV and radio can have kW of power and their primary mission is to relay large amount of data. In contrast, a weather or early-warning satellite's primary mission is to gather and downlink the imagery. I would generally assume such missions would transmit with less power and less regularly. The frequency might also shed light on military vs. civilian use, as different portions of the EM spectrum is often allocated to each.

For LEO satellites the orbit and constellation size will help. Sun synchronous orbits are often used for remote sensing because of repeatable lighting conditions over the same targets. Polar orbits are common for weather satellites. A couple of satellites flying in close tandem where one was constantly blasting land with radar sounds like a synthetic aperture radar mission.

Molniya orbits are used almost exclusively for high-latitude communications because of their long loiter times over high latitudes.