Over the past six months, SpaceX Starlink satellites have completed 50,000 collision avoidance maneuvers.

SpaceX’s Starlink satellites have completed nearly 50,000 collision avoidance maneuvers over the past six months, roughly double the number in the previous half of the year, Space.com reports. While experts praise Elon Musk’s aerospace company for its commitment to transparency, they also warn about the consequences of skyrocketing orbital traffic.

Image source: Spacex

SpaceX reported an increase in the number of forced maneuvers of its Starlink satellites in the latest semi-annual report on the status of its satellite constellation, which was filed with the US Federal Communications Commission (FCC) on July 1. The report found that on average, each Starlink satellite fired its thrusters 14 times between December 1, 2023, and May 31, 2024, to avoid orbiting objects, including other Starlink satellites, spacecraft owned by other operators, and pieces of space debris. Over the same six-month period, the Starlink constellation grew from approximately 5,100 to 6,200 active vehicles.

The company also said it had lowered the satellite maneuvering threshold by another degree. This means that they now change position to avoid a potential collision, even when the probability of such a collision is only one in a million. This threshold, as stated in the SpaceX report, is 100 times lower than the industry standard.

SpaceX began deploying Starlink in May 2019 and in just a few months became the world’s largest satellite operator. But the company’s satellites have quickly become a source of concern for near-Earth safety experts because they have created a reality in which collision avoidance maneuvers have become a daily necessity rather than an occasional inconvenience. For the first four years after Starlink’s initial launch, the number of evasive maneuvers doubled every six months, reaching 25,299 in the six months leading up to May 31, 2023. However, between May and December 2023, the number of maneuvers remained unchanged, despite the continued growth in the number of satellites.

The recent doubling in the number of maneuvers should be due largely to the lowering of the maneuvering threshold that SpaceX reported, Hugh Lewis, a professor of astronautics at the University of Southampton in the UK and a leading European expert on space safety, told Space.com .

«Starlink satellites would have completed approximately 25,000 maneuvers between December 1, 2023 and May 31, 2024 if the threshold had remained the same. This is approximately the same level as in the two previous semi-annual reports, despite the increase in the number of satellites in the constellation,” the expert noted.

Lewis has been following satellite megaconstellations and their impact on orbital security for many years. He said he expected a larger increase in the number of Starlink satellite maneuvers given the growing size of the constellation.

«I expected that increasing the size of the satellite constellation would lead to more maneuvers, but I suspect that increasing solar activity is also leading to a reduction in the amount of debris around the Starlink spacecraft’s orbit. These two factors seem to lead to an obvious curb on the growth in the number of maneuvers,” the expert noted.

As Space.com explains, near-Earth space weather, formed by coronal mass ejections and other solar activity, thickens the tenuous gas in the planet’s upper atmosphere. As a result, spacecraft experience greater drag, which pulls them to lower altitudes. A powerful solar storm that hit Earth in May this year, causing auroras around the world, caused the altitude of active low-Earth orbit satellites to drop by nearly half a mile (about 800 meters), according to a recent study. The study estimates that the orbital altitude of failed or spent satellites and other space debris objects could have decreased by several kilometers during this four-day event, which would subsequently lead to their faster return to the dense layers of the Earth’s atmosphere and combustion.

The European truck “Jules Verne” burning in the Earth’s atmosphere. ESA 2015 photo

Starlink satellites make decisions to avoid other objects autonomously using on-board artificial intelligence. While the growing number of maneuvers is intended to make orbital operations safer, they could also have a negative impact on predictions of future collisions. A study by the Commercial Space Operations Center of Pennsylvania (COMSPOC) published last year found that each collision avoidance maneuver disrupts satellite trajectory forecasts by several days. After maneuvers, the actual position of the satellites can differ from the predicted position by up to 25 miles (40 kilometers), reducing the accuracy of forecasts of potential collisions.

Lewis added that the more maneuvers Starlink satellites make, the faster they use up fuel, which leads to a shorter lifespan. SpaceX is trying to maintain a policy of reducing debris with its Starlink project, so it removes satellites from orbit at the end of their service life. During the six-month period covered in the company’s latest report, only one satellite failed to deorbit as expected.

SpaceX continues to expand its Starlink satellite constellation, which could eventually include up to 42,000 vehicles. Lewis predicts that the number of Starlink satellite evasive maneuvers will continue to rise over the next few years, reaching 80,000 per half year by 2027.