SpaceX has stated that a “bug” in its system prevented operators from changing the course of one of its Starlink satellites after experts attempted to communicate a potential collision with another satellite, resulting in the European Space Agency (ESA) conducting the first-ever “collision avoidance maneuver” with a satellite from the new breed of "mega-constellation" satellites.
In a slew of tweets, the space agency confirms that its Aeolus Earth observation satellite fired its thrusters in order to avoid a collision with the SpaceX satellite in their Starlink constellation, a mega-constellation of 60 satellites launched earlier this year in hopes of providing ultrafast Internet access.
“Experts in our space debris team calculated the risk of collision between these two active satellites, determining the safest option for Aeolus would be to increase its altitude and pass over the SpaceX satellite,” wrote ESA in a tweet.
The maneuver took place about a half an orbit before the collision would have happened. Shortly after, Aeolus sent science data back indicating the maneuver was a success. The agency notes that “it is very rare to perform collision avoidance maneuvers with active satellites. The vast majority of ESA avoidance maneuvers are the result of dead satellites or fragments from previous collisions.”
In a statement seen by Jonathan O'Callaghan reporting for Forbes, SpaceX said that their last communication with the Aeolus operations team was on August 28 when the probability of collision was “well below the industry standard threshold” at which point both SpaceX and ESA determined that a maneuver was not necessary. In the days that followed, the US Air Force updates increased the risk of collision to 1-in-10,000 but a “bug” in SpaceX's paging system prevented the Starlink operator from “seeing the follow-on correspondence on this probability increase.”
“SpaceX is still investigating the issue and will implement corrective actions,” SpaceX said. “However, had the Starlink operator seen the correspondence, we would have coordinated with ESA to determine [the] best approach with their continuing with their maneuver or our performing a maneuver.”
Last year, 28 collision avoidance maneuvers were conducted by ESA, but experts warn that as the number of satellites in orbit increases, hundreds or even thousands of satellites may be compromised. Such maneuvers are currently conducted manually and take a good deal of preparation, but the agency says that it is preparing to automate the process using artificial intelligence. Current estimates suggest that all the debris in Earth’s orbit weighs more than 8,400 tonnes.