Sep. 15, 2010 at 6:24 PM ETSpace-watchers say China is still doing whatever it started doing last month with two close-flying satellites in orbit. And that's keeping outside observers worried about the fact that Chinese officials have not yet actually said what it is they're doing.The maneuvers, which appear to involve rendezvous operations between the SJ-06F satellite and the more recently launched SJ-12 craft, could amount to practice for space station dockings or coordinated satellite observations from orbit. Few folks would have a problem with that. But they also could be aimed at developing the expertise for lurking near someone else's satellte and eavesdropping, or even knocking that satellite out of commission in the event of a crisis. That's the worrisome part.The formation-flying exercise began in mid-August, and stirred up a significant fuss a couple of weeks ago when some observers speculated that the SJ-12 might have given a nudge to the SJ-06F. China says the satellites in the SJ series (SJ stands for "Shijian," or "Practice" in Chinese) are designed for scientific purposes, but space experts suspect that they actually are being used for military surveillance.Amateur satellite observers around the world say the two spacecraft are still flying close together, a month after the maneuvers began. The U.S. military's tracking data have shown that they're separated by about half a mile (1 kilometer), NBC News analyst James Oberg noted in an e-mail. "This close-in relative position requires positive control — thruster firings — and onboard navigation to determine how to direct the steering jets," Oberg said.Back in August, the U.S. Strategic Command confirmed that there were "two satellites in close proximity with each other" but said it could not confirm "if they have made physical contact."Now Oberg passes along a new Defense Department statement, which says both less and more at the same time:"Orbital analysts at the Joint Space Operations Center are still tracking both objects and continue to monitor them for conjunctions as part of their routine conjunction screenings for all active satellites. Providing specific details on position/proximity would move into classified and/or sensitive information."The statement signals that the Pentagon will no longer be discussing the satellites or whether there's a chance that they could collide with each other (in a conjunction). Such details are now considered "classified and/or sensitive information."If there are any future conflicts between technologically advanced nations, one of the battlefronts could well be in outer space. China sparked a debate over the potential for "space war" in 2007 when it sent up a missile to knock down one of its own satellites in 2007. Beijing didn't confirm the existence of that space maneuver until nearly two weeks after it occurred. A year later, it was China's turn to express concern when the Pentagon conducted its own satellite-downing operation.The United States and Russia have been conducting orbital rendezvous for decades. Without that capability, you can't build a space station or walk on the moon. Few people would begrudge the Chinese the opportunity to develop a similar capability for their own space program. The only problem is that there's been no official information about the satellite maneuvers from Beijing (although the maneuvers have been the subject of unofficial debate inside as well as outside China)."So far, still no official or even off-the-record disclosure from Beijing that this new experiment is in progress for a month," Oberg said. "That lack of official information can legitimately be considered 'information' about the mission goals and their probable military purposes."Join the Cosmic Log corps by signing up as my Facebook friend or hooking up on Twitter. And if you really want to be friendly, ask me about "The Case forPluto."