China has pulled off a tricky and uncommon feat in space flight, manoeuvring one of its satellites to within about 300 metres of another while they were orbiting Earth, space analysts say.
Some analysts view the rendezvous as a potentially ominous sign of China’s ability to carry out a hostile act or espionage against a rival satellite in space. Others say it could have been a test of docking skills.
China is not saying why it conducted the August manoeuvre, but it comes as the country is ambitiously expanding its space program, including building a space station and conducting lunar missions. It is expected to launch the first module of its space station next year, followed by a manned spacecraft to dock with it.
Using unclassified tracking data from the U.S. military, space-watchers calculated that China manoeuvred its SJ-12 satellite close to its SJ-06F satellite on about Aug. 19.
The military releases estimates on the paths of about 1,000 active satellites and 20,000 pieces of debris in space to help commercial and civil satellite operators avoid collisions.
U.S. military officials confirmed the Chinese satellite rendezvous occurred but released few details, citing security concerns. Chinese space officials didn’t respond to written questions.
The rendezvous marks a milestone for China’s space skills, said Brian Weeden of the Secure World Foundation, a Colorado think-tank that focuses on the use of space.
Manoeuvring an unmanned orbiting vehicle from a control room on Earth is extremely difficult because of the distance and because data on the location of the vehicle can be off by hundreds of metres, he said.
“It’s not like driving a car,” Weeden said.
Only a few other countries have shown they can pull it off, including the U.S., Russia and Sweden, Weeden said.
Gregory Kulacki, who tracks developments in China for the Union of Concerned Scientists, called it a “cutting-edge skill” and said it’s a significant achievement for China.
“It shows they are keeping up with developments in international space technology,” he said.
Any time ground controllers can manoeuvre a satellite into close proximity with one that can’t be manoeuvred, the exercise has “potential anti-satellite implications,” said Kulacki.
While the SJ-12 satellite changed course for the rendezvous, the SJ-06F has never previously shown it is manoeuvrable, Weeden said.
With no information from the Chinese, pinning down the reason for the manoeuvre is difficult, analysts said.
China may have been practising its docking skills as quietly as possible, so that if it failed, it wouldn’t be a public embarrassment, said Charles Vick of Globalsecurity.org, which tracks military and homeland security news.
Vick said the rendezvous might have been a dual-purpose exercise to practice anti-satellite skills as well as docking or inspection.
“It certainly is very ominous in the sense that it is saying China is demonstrating a capability they could utilize in a not-so-positive way,” Vick said.
“China does really not have our best interests in mind,” Vick added. The satellite rendezvous could be viewed as a skill China could use “under hostile circumstances,” he said.
Weeden said it’s unlikely the rendezvous was an anti-satellite test because SJ-12 approached the other satellite at a low relative speed, changing course six times over several days.
If the goal had been to destroy the other satellite, SJ-12 would have closed in at faster speed, he said.
China showed in 2007 that it could to that, destroying one of its own satellites with a missile. That prompted international criticism because it created thousands of pieces of orbiting debris.
Although China didn’t publicly confirm the rendezvous, it was spotted quickly. The first public report appears to have come on Aug. 22, just days after the closest approach, by Russian space observer Igor Lissov in the Russian news agency Interfax-AVN.
It has been discussed on numerous websites since then, including by Weeden on thespacereview.com.
“It reinforces the fact that it’s really hard to hide things in space,” Weeden said.