The dramatic growth in Starlink collision-avoidance maneuvers in the past six months is fueling concerns about the long-term sustainability of satellite operations as thousands of new spacecraft are set to launch into orbit in the coming years.
SpaceXs Starlink The Broadband satellites were forced to orbit more than 25,000 times between December 1, 2022, and May 31, 2023, to avoid dangerous approaches to other spacecraft and orbital debris. Report Filed by SpaceX with the US Federal Communications Commission (FCC) on June 30. This is more than double the number of avoidance maneuvers reported by SpaceX in the previous six-month period from June to November 2022. Since the launch of the first Starlink spacecraft in 2019, SpaceX satellites have been forced to move more than 50,000 times to avoid collisions.
The steep increase in the number of maneuvers worries experts as it follows an exponential curve, leading to concerns that the safety of operations in the orbital environment could soon get out of hand.
„Right now, the number of maneuvers is growing exponentially,” Hugh Lewis, a professor of space at the University of Southampton in England and a leading expert on the impact of megaconstellations on orbital security, told Space.com. „It doubles every six months, and the problem with exponential trends is that they reach very large numbers very quickly.”
Related: How many satellites can be safely fixed in Earth orbit?
1 million maneuvers by 2028
Data compiled by Lewis shows that Starlink satellites conducted 2,219 collision-avoidance maneuvers in the first half of 2021. The figure rose to 3,333 in the next six-month period ending December 2021, and then more than doubled to 6,873 between December 2021 and June 2022. In the second half of 2022, SpaceX had to change the trajectories of its satellites 13,612 times to avoid potential collisions. . In a recent report to the FCC, the agency reported 25,299 collision-avoidance maneuvers over the past six months, with each satellite moving an average of 12 times.
„Right now, every six months, the number of maneuvers being performed doubles,” Lewis said. „That’s a 10-fold increase in two years, and if you project it, 50,000 in the next six-month period, then 100,000 in the next, then 200,000, and so on.”
If this trend continues, by 2028, Starlink satellites will need to maneuver nearly a million times in half a year to reduce the risk of orbital collisions. Lewis doesn’t expect such growth to slow down anytime soon. SpaceX has so far deployed about a third of its planned first generation of 12,000 spacecraft and is launching at a regular pace of more than 800 satellites per year, which is expected to continue for the foreseeable future.
However, the first generation Starlink constellation was just the beginning. The FCC has partially approved plans for the second-generation Starlink constellation, which will include 30,000 satellites. Other players around the world, including Amazon with its Project Kuiper and China’s Guang, are scrambling to secure orbital slots with their respective regulators.
Like turning every 10 meters on the highway
More than 1.7 million satellites are registered with the International Telecommunication Union, the United Nations agency that oversees the use of radio frequencies by satellites, according to Joan Wheeler, a satellite regulatory expert at Alton Legal and head of the UK-based Satellite Finance Network. . While it’s unlikely that all of those plans will come to fruition, the questionable numbers are so high that experts like Lewis question whether order can be maintained in orbit.
„If we expect to have 100,000 active satellites by the end of this decade, my suspicion is that the number of maneuvers by all the spacecraft operators combined will be enormous,” Lewis said. „You do maneuvers to mitigate high-risk events, but it’s like driving on the highway and swerving every 10 meters to avoid a collision. It’s not safe.”
There are currently 10,500 satellites orbiting our planet, of which 8,100 are operational. European Space Agency. Things have started to get very crowded lately. For example, in 2019, there were only about 2,300 active satellites orbiting the planet. Statesman. A key driver of growth is Starlink, the largest satellite constellation ever assembled.
New satellites are not the only reason for the need for orbiting. Size Space debris — defunct spacecraft, old rocket stages and various pieces of debris — and continues to grow, making it difficult for operators to keep their spacecraft safe.
SpaceX currently conducts an evasive maneuver every time orbital models show the probability of one of the Starlink satellites crossing the path of another object is greater than 1 in 100,000. That limit is 10 times lower than the standard set by NASA and other international agencies.
However, Lewis questioned whether SpaceX could maintain such a high standard as the number of „connection alerts” continued to snowball. He adds that despite the company’s efforts, the residual risk of conflict will continue to rise.
Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics and another cautionary voice often heard in the satellite megaconstellation debate, agrees with Lewis: „SpaceX is confident they can handle the increased maneuvering load,” McDowell told Space.com. An email. „I don’t believe SpaceX properly accounted for non-statistical errors (the probability that independent and unpredictable screwups combine to give a bad outcome – a collision). Safe.”
Starlink relies on an autonomous collision avoidance system that instructs the satellites to maneuver based on models of the orbits of objects in space. These models provide alerts several days in advance and may not always be received correctly. Also, other factors such as changes in density Earth’s atmosphere At high altitude Caused by space weatherThis may affect the accuracy of the calculations.
„There is a concern about mergers occurring where no maneuvers have been made,” Lewis said. “You could argue that probability [of a collision in these cases] Very few, but in very large numbers, they represent a very significant risk. It’s like buying a lottery ticket. If you buy just one, you have no chance of winning, but if you buy a million tickets, you have a good chance.”
Unless regulators limit the number of satellites in orbit, Lewis expects collisions to soon become a routine part of the space business. Such collisions lead to rapid growth in the amount of space debris out of control, leading to more collisions. This may be the end point of the process Kessler syndromeIt was predicted by former NASA physicist Donald Kessler in the late 1970s. Portrayed in the 2013 Oscar-winning film „Gravity,” Kessler syndrome is a cascade of unstoppable collisions that render parts of the orbital environment completely unusable.