SpaceX said that a bug in its communications system was to blame over the ESA and Starlink near-collision. The agency added that it is not in their intention not to move one of its Starlink satellites to avoid colliding with the European Space Agency’s Aeolus satellite in orbit.
On September 2, the ESA sent out a thread of tweets indicating that they had to manually perform an avoidance maneuver to avoid a collision with one of SpaceX’s Starlink satellites in orbit.
The decision the space agency made was after calculating a higher than usual probability that the two satellites might collide.
According to one of the tweets, the ESA indicated that it was the first time that it had performed such maneuver from an active or operating satellite, much from a “mega-constellation” of satellites.
Earlier on Thursday, the ESA identified that a potential SpaceX Starlink satellite had a probability of 1 out of 50, 000 chance to collide with the Aeolus — space weather and Earth-observing spacecraft launched in August 2018.
At the time, the ESA was in contact with SpaceX and have both agreed that the probability was too high of a number to cause concern.
Most of the Starlink satellites have raised their orbits to around 342 miles (550 kilometers) up, but SpaceX is currently testing its de-orbiting techniques with three of its satellites from the Starlink constellation, which made it align with ESA’s Aeolus at the relatively low orbit, about 198 miles (320 kilometers).
And as days passed by, the ESA continued monitoring the course of the two satellites, gathering data from the U.S. Space Surveillance Network, an array of ground-based telescopes that track objects in orbit, and combined it with their internal data about the size and shape of the Aeolus spacecraft.
As the two satellites drew closer, however, ESA scientists calculated that the probability was raised to 1 out of 1000 chance of impact, which was ten times more than the recommended number to make preventive measures.
Officials at ESA said that they contacted SpaceX about the higher probability and asked if the company had any plans to move the Starlink satellite. However, initial reports indicated that SpaceX refused to coordinate with the ESA, who ultimately decided to perform the collision avoidance maneuver themselves.
In emails sent by SpaceX to reporters, however, the space company indicated that they were not able to receive the notice from ESA regarding the higher probability calculations and that the bad communication was not intentional, blaming a bug in the company’s “on-call paging system.”
“SpaceX is still investigating the issue and will implement corrective actions,” a company spokesperson said in a statement. “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.”
Referring to SpaceX’s Starlink as a “mega constellation” is a bit of a stretch at the moment, given that the system currently consists of 60 satellites. This initial batch of satellites was delivered to low Earth orbit in May aboard a Falcon 9 rocket, and it’s the first of many planned deployments.
SpaceX envisions a constellation consisting of at least 12 thousand satellites, which would collectively provide broadband internet to paying customers regardless of where they are in the world.
It does, however, highlight the ESA’s compelling call to action regarding international space littering and its unilateral plans of introducing a new market that would address the issue.
The ESA themselves said collisions are not a rare incident in Earth’s lower orbit. The space agency has performed at least 28 collision avoidance maneuvers across its fleet in 2018.
And as the ESA tweeted yesterday, as “the number of satellites in orbit increases, due to “mega-constellations” such as #Starlink comprising hundreds or even thousands of satellites, today’s ‘manual’ collision avoidance process will become impossible…”
Notably, there are now well over an estimated million pieces of space debris larger than 1 centimeter in orbit around Earth. Each one has the potential to collide with and destroy another satellite, creating hundreds of thousands of more pieces of space debris.