The two Chinese "Shi Jian" ("Practice") satellites called SJ-06F and SJ-12 are officially designated as science spacecraft and their mission comes in advance of the launch of China's planned space station.
The first space station module (Tiangong-1) is set for launch in 2011 and to give the docking sensors and control systems a "test run" before trying it out on the space station could be the purpose of SJ-06F and SJ-12. But why all the secrecy?
"This sort of thing may very well be consistent with wanting to test drive the hardware and software before you test it on your space laboratory," said Dean Cheng, a Chinese policy expert with the Heritage Foundation, a think tank in Washington DC. "You'd be doing it on a smaller, cheaper, less prestige-oriented item so that if something went wrong, it wouldn't necessarily be politically disastrous."
Also, China keeping the "test drive" quiet may seem fishy, but it is understandable, especially if the test docking procedure wasn't successful. National pride most likely dictated the silence.