Satellites in SpaceX’s Starlink mega-constellation have performed nearly 50,000 collision avoidance maneuvers in the past six months, nearly twice as many as in the previous six months. Experts are praising Elon Musk’s space company for its commitment to transparency but warning of the consequences of rapid growth in orbital traffic.

SpaceX reported the increase in its latest semiannual report on the constellation’s status, filed with the U.S. Federal Communications Commission (FCC) on July 1. According to the report, each Starlink satellite fired its engines an average of 14 times between December 1, 2023, and May 31, 2024, to intercept objects in orbit, such as other Starlink satellites, spacecraft belonging to other operators, and pieces of space debris. In the same six months, the Starlink constellation’s approximately 5,100 operational satellites reached 6,200 spacecraft.

SpaceX also said it has lowered its maneuver threshold by an additional order of magnitude, meaning its satellites now move to avoid a potential collision when the chance of an explosion is only one in a million. SpaceX said in a report that this threshold is 100 times lower than the industry standard.

SpaceX began deploying its Starlink constellation in May 2019, and within months it had become the world’s largest satellite operator. The mega-constellation quickly became a source of concern for space stability experts, as it ushered in a whole new era of orbital traffic where collision avoidance maneuvers have become a daily necessity rather than an occasional inconvenience. In the first four years after Starlink’s initial launch, the number of avoidance maneuvers doubled every six months, reaching 25,299 in the semiannual period through May 31, 2023. There was no change in the number of maneuvers from May to December 2023. Despite the increase in the number of satellites.

Hugh Lewis, a professor of astronautics at the University of Southampton in the United Kingdom and one of the leading European experts on space sustainability, told Space.com that the recent doubling is largely due to the lowered maneuvering threshold that SpaceX is currently using.

“If the threshold had remained the same, Starlink satellites would have performed approximately 25,000 maneuvers between December 1, 2023 and May 31, 2024,” Lewis said. “This is about the same as the previous two six-month reports, despite the increase in the number of satellites in the constellation.”

Lewis, who has spent years observing the effects of mega-constellations on orbital safety, said he would expect more maneuvers given the constellation’s growing size.

“I would expect the increase in the size of the constellation to lead to more maneuvers, but I suspect that the increase in solar activity is also causing a decrease in the amount of debris around Starlink’s altitude,” Lewis said. “These two competing effects appear to be leading to a clear stabilization in the number of maneuvers.”

Space weather around Earth, caused by coronal mass ejections and other solar flares, concentrates the thinned gas in the upper atmosphere of the planet where the satellites orbit. As a result, spacecraft there are subject to more drag, which pulls them to a lower altitude. A powerful solar storm that hit Earth in May of this year caused spectacular auroras around the world and reduced the altitude of the satellites. low earth orbit almost half a mile. Dead satellites and other pieces of space debris can sink several kilometers within four days, reentering Earth’s atmosphere, researchers say.

Starlink satellites autonomously decide to avoid other objects with the help of onboard artificial intelligence. While the increased number of maneuvers is intended to make orbital operations safer, it can also have a negative impact on future collision predictions. A study published last year by the Pennsylvania-based Commercial Space Operations Center (COMSPOC) found that each collision avoidance maneuver changes satellite path predictions by several days. After the maneuvers, the satellites’ actual location can be 25 miles (40 kilometers) different from the predicted location, making collision predictions inaccurate.

Lewis added that the more Starlink satellites maneuver, the faster they burn through their fuel, which shortens their lifespan. SpaceX maintains a zero-waste policy for Starlink, which is why it deorbits the satellites at the end of their lifespan. Only one satellite failed to deorbit during the six-month period covered by the latest report.

SpaceX continues to build its Starlink mega-constellation, which could eventually include up to 42,000 satellites. Lewis predicts the number of Starlink escape maneuvers will continue to grow over the next few years, reaching 80,000 in the six months to 2027.