On July 29, a Chinese Long March-4C rocket blasted into space from the northern Taiyuan Space Center carrying three secretive, experimental satellites. Not really all that unusual by itself — a robotic arm reportedly on one of the satellites could be involved in testing for Beijing’s far-off space station program.

But once they were in orbit, the satellites began acting very, very strangely.

More precisely, one of the satellites, known as SY-7, was moving all over the place and was appearing to make close-in rendezvous’s with other satellites. It was so strange, space analysts wondered whether China was testing a new kind of space weapon — one that could intercept other satellites and more or less claw them to death.

It’s not as crazy as it sounds. The U.S. has experimented with anti-satellite weapons, and is even researching how to cannibalize satellites in orbit. China has even blown up one of its own satellites with a missile. That caused an international outcry considering the giant cloud of debris which has come close to imperiling space travel for a century.

But a claw might be more discreet.

SY-7 launch of July 29, 2013. Xinhua photo

Space mystery

Most satellites are pretty dumb, in the sense that they don’t really move around a whole lot except in a fixed orbit. Doing much more than that requires sophisticated guidance, navigation and control systems to the point where the satellite becomes something more like an unmanned spaceship.

Have those things, and you have the rudimentary steps to maneuver in the path of other satellites. Once you’re there, you then might want to use the maneuverable satellite to conduct inspections or repairs — or even potentially attack other (more helpless) satellites.

At least one of the satellites launched by China appears to have some form of that capability. On Aug. 16, the satellite known as SY-7 made a major orbital adjustment, dropping down by about 93 miles. Robert Christy, a British astronomer who tracks Russian and Chinese satellites on his blog Zarya, believed SY-7 was practicing docking on a simulated space station — a planned project by China’s space program — or perhaps testing out a rendezvous with one of its companions.

Instead, over the next several days, SY-7 suddenly changed course and rendezvoused with a completely different satellite — one that had been up there all along. The two satellites came as close as a few hundred meters.

These sudden maneuvers ruled out the trio as simple ocean surveillance satellites, which also fly in formation and which China has increasingly launched to monitor disputed sea territories. For one, ocean surveillance sats tend to fly with big gaps between them — 30 to 120 miles — thus covering more territory. But the trio orbiting now have come as close as two miles. And ocean surveillance satellites don’t move back and forth.

Jonathan McDowell, an astrophysicist with the Harvard-Smithsonian Center for Astrophysics and author of the sat-tracking newsletter Jonathan’s Space Report, reported that at least one of the satellites wields a robot-manipulator arm developed by the Chinese Academy of Sciences.

Could it be an anti-satellite weapon? This would be a satellite capable of impacting with other satellites, destroying them with sheer kinetic force, or detonating explosive charges nearby like a satellite suicide bomber. The manipulator arm could also be potentially used as a weapon, grabbing away and plucking bits off an enemy satellite like it was an insect.

Collisions and explosions are also diplomatically tricky. When China blew up one of its own satellites with a missile in 2007, it created a massive cloud of debris around the Earth — most of which will still be there a hundred years from now.

DART concept. NASA illustration

Anti-satellite

But according to Brian Weeden, the satellites are doing what’s called an “on-orbit inspection.” Weeden, who is a technical and space adviser to the Secure World Foundation, would have a pretty good idea — as an Air Force officer he developed tactics for the Pentagon’s Joint Space Operations Center.

“If a satellite stops working for some reason, it can be very difficult to figure out what went wrong using ground-based sensors,” Weeden says. “A satellite that can get up close and take some pictures could be very helpful.”

If another satellite somewhere in space has a malfunction, an inspection satellite could come to the rescue or at least rendezvous and determine what went wrong.

That said, there’s still a fuzzy distinction between a satellite that can inspect another satellite, and a satellite that can mess with someone else’s satellite, he adds. A grabby-armed satellite that can inspect satellites in distress could perhaps turn that arm into a weapon.

“One could dream up a whole bunch of dastardly things that could be done with a robotic arm in close proximity,” Weeden says.

However, this isn’t just true for only China’s satellites — it’s true for the U.S. as well. America has experimented with several dual-use orbiters with inspection capabilities that could also be used as a potential weapon. In 2009 the Pentagon launched two secretive inspection satellites to scope out a derelict military satellite. The inspection satellites, known as Mitex, were developed by Lockheed Martin and are widely believed to also have the ability to “inspect” satellites from Russia and China.

Another Pentagon project, called DART, ended in 2005 when the satellite’s navigation system failed during an approach to an orbiting communications relay. DART collided with the relay, knocking itself out of action and ending the mission prematurely.

The Air Force also has a satellite called XSS-11 — currently in orbit — which is essentially a giant camera. The satellite, which is about the size of a washing machine, is designed to maneuver close to other satellites and take snapshots in case something goes awry. The Swedish government has also experimented with a pair of maneuverable satellites called Mango and Tango. And the Pentagon’s blue-sky researchers at the Defense Advanced Research Projects Agency have been experimenting with a program called Phoenix designed to pick apart dead satellites for spare parts.

“The U.S. or Sweden will insist these are in no way space weapons programs,” Weeden says. “But the technology is definitely dual-use, and can raise significant misperceptions when used in a secretive manner.” The same is true for Beijing.

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