China Used a Satellite to Pull Another One Out of Its Orbit

And U.S. officials are concerned the technology could be militarized.
Chris Young
A Long March-3B rocket launching SJ-21.Xinhua

Space tugs are designed for the peaceful extraction of defunct satellites, but if they're programmed to do so, they could deorbit another space agency's active satellite.

A Chinese space tug satellite, Shijian-21 (SJ-21), grabbed onto one of the country's other satellites and pulled it out of its orbit into a "super-graveyard drift orbit", a report from The Drive reveals. The new development has drawn concern from U.S. officials, who say the technology could be used to compromise other countries' satellite operations.

Escorting satellites to a graveyard orbit

On Jan. 22, satellite tracking firm Exoanalytic Solutions — which was awarded a contract in 2021 to provide data to the U.S. Space Force — observed SJ-21 disappear from its regular orbit. The satellite then executed a "large maneuver" that brought it side by side with China's dead BeiDou Navigation System satellite. SJ-21 then proceeded to pull the dead satellite out of its geosynchronous orbit and then escorted it to a higher graveyard orbit, designated for satellites that have come to the end of their lifespan.

SJ-21 was launched into orbit on October 24, 2021, aboard a Long March-3B. According to Chinese state media, the satellite was designed to "test and verify space debris mitigation technologies." In November last year, SJ-21 was observed orbiting near an unknown object in what appeared "to be a deliberate synchronization." China never confirmed the nature of the unknown object, though the U.S. Space Force announced it might be a spent apogee kick motor. Others theorized it might be an experimental payload, designed to allow SJ-21 to test its capabilities.

Space repairs and orbital relocations

Though SJ-21's mission might simply be aimed at peaceful satellite extraction, concerns remain due to the fact that the technology could be used to deorbit any satellite and send it into a graveyard orbit or hurtling towards Earth. The U.S. Space Force, itself, has commissioned Northrop Grumman to develop a satellite with a robotic arm that can carry out repairs and relocations of other satellites in orbit. Northrop Grumman has already tested the technology in space and a fully functioning machine is scheduled to launch in 2024.

While the U.S. and China are improving their capabilities for complex in-orbit satellite maintenance, there are also concerns that some of these technologies may be utilized for military space operations. After all, in August 2020, the U.S. Space Force published its 'Spacepower' military doctrine, in which it stated that its "adversaries' actions have significantly increased the likelihood of warfare in the space domain." With that doctrine, the U.S. turned its back on a decades-long global effort to maintain space as an un-militarized domain.

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