STARLINK ‘BREAKS SPACE TRAFFIC SAFETY RULES’
With SpaceX’s newest satellites ignoring 10km minimum distance, China may have to follow suit to prevent giving US upper hand, researchers say
A team of Chinese space engineers has accused SpaceX’s Starlink satellites of breaking the traffic rules of Earth’s lower orbit and warned that China will be giving the US an upper hand if it does not follow suit.
The researchers said two of Starlink’s newest satellites, equipped with high-speed laser communication devices, came within 4.9km of each other on June 30. The commonly accepted – if unwritten – minimum distance to avoid collision is 10km.
In a study published by Chinese peer-reviewed journal Radio Engineering, the researchers said the unusually dense formation was no accident, but the result of a complex scheme by SpaceX to maximise the performance of its laser communications.
The technology requires the sending and receiving devices to stay within a straight line of sight over a certain distance, they said. Nor was it the only example of Starlink satellites ignoring the accepted traffic rule, the researchers found.
Yu Shunjing, a satellite design engineer with China’s largest manufacturer of the devices DFH
Satellite Co, and his co-authors, said the rapid development of large-scale constellations “will make space, especially the lower Earth orbits, very crowded”. “We must establish a new ‘space traffic rule’ based on new technologies, otherwise the development of Chinese constellations will be seriously restricted,” they said.
A Beijing space scientist who was not involved in the study warned a change in the minimum distance could increase the risk of a collision in Earth’s lower orbit.
While active collision avoidance systems could reduce the risk of accidents, “even the best technology can fail sometimes”, said the researcher, who asked not to be named because of the issue’s sensitivity.
Five kilometres may provide plenty of room on the ground but a satellite can cover that distance in half a second, he said. “The existing safety limit is based on scientific calculation. Crossing the line could lead to some dangerous consequences, because one collision can lead to another.”
China is keeping a close watch on SpaceX’s commercial satellite programme, which provides internet access to civilian and military users, and this is not the first time Chinese scientists have voiced their concerns.
After observing Starlink’s role in supporting Ukraine’s internet communications during the Russian invasion, a group of Chinese military researchers in May urged Beijing to develop the capability to destroy the network if necessary.
When completed, Starlink will consist of tens of thousands of satellites, a network that conventional anti-satellite weapons such as missiles will not be able to destroy entirely.
But Starlink’s early infrastructure has a problem: it needs ground stations to pass data from one satellite to another, or signal-relaying ships when the devices are flying over the oceans.
These facilities not only increase operational costs and limit bandwidth, they can also become vulnerable targets in a war.
The new generation of satellites launched by SpaceX in September last year is an attempt to overcome these problems, by using laser beams to communicate directly with each other.
A year later, more than 1,400 laser satellites are now circling the planet, with 880 in active service and providing high-speed communications to some parts of the globe, according to the Chinese study’s estimates.
Yu’s team said high-resolution radar images suggested that each satellite is carrying several laser transmitters pointing in different directions, allowing them to establish communications with similar devices in the same or nearby orbits over a distance of up to 2,500km.
The researchers said SpaceX was putting these satellites into closely neighbouring orbits to increase communications coverage and lessen signal interruptions, with collision avoidance clearances far below the generally accepted threshold.
SpaceX has been approached for comment on the study’s claims.