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The SpaceX satellite was on a "collision course" until the ESA satellite was routed



  Illustration of an Aeolus satellite of the European Space Agency orbiting the Earth.
Magnification / Illustration of the European Space Agency's Aeolus satellite.

Yesterday, the European Space Agency (ESA) took action to avoid a collision with SpaceX's broadband satellite after an error in SpaceX's paging system prevented the company from receiving a crucial update.

"For the first time, ESA performed a" collision avoidance maneuver "to protect one of its satellites from collision with a" mega constellation, "ESA said on Twitter . The "mega constellation" referred to by ESA is SpaceX's StarX broadband system, which is in its early stages of deployment but could eventually include nearly 12,000 satellites.

Action had to be taken since ESA's Aeolus satellite and Starlink were on a course that had more than 1 in 10,000 chance of collision. According to ESA Earth observation satellite Aeolus "fired its ejectors, moving it from a collision course with a SpaceX satellite into their Starlink constellation."

SpaceX's paging system failed

A Forbes article yesterday originally had the headline, "SpaceX refused to move Starlink satellite with risk of collision with European satellite", and the piece includes quotes from the head of Space Fragment's Office. ESA Holger Krag:

"Based on that, [collision risk] we informed SpaceX who responded and said they did not plan to take action," says Krag, who said SpaceX informed them by email – the first contact to was made with SpaceX, despite repeated attempts by Krag and his team to connect with t then starlink starts. "At least it was clear who should react. So we decided to react because the collision was close to 1 in 1000, which was ten times higher than our threshold. "

SpaceX explained in a statement today that you did not initially take action because of early estimates that the risk of a collision was much lower than it turned out to be. SpaceX has said it will coordinate with the ESA to avoid a collision after the ratings deteriorate if only a paging system error does not prevent SpaceX from receiving an update on the probability of a collision. SpaceX said it was trying to correct the error to prevent such accidents in the future.

Here is the full statement SpaceX provided to Ars:

Our Starlink team last exchanged an email with Aeolus operations team on August 28, when the collision probability is only in the 2.2e-5 range (or 1 50k) well below the standard threshold of 1e-4 (or 1 in 10k) and 75 times lower than the final rating. At this point, both SpaceX and ESA decided that a maneuver was unnecessary. Then the US Air Force updates show the likelihood of increasing to 1.69f-3 (or more than 1 in 10,000), but an error in our on-call paging system prevented the Starlink operator from seeing subsequent correspondence on this increase in probability – SpaceX is still investigating the issue and will take corrective action. However, if the Starlink operator saw the correspondence, we would coordinate with ESA to determine the best approach for continuing their maneuver or performing the maneuver.

We contacted Krag and the ESA press office and they directed us to an article published today on the ESA website. Craig made it clear he did not blame SpaceX, but said the incident underscored the need for better collision avoidance systems.

"No one is to blame here, but this example shows the urgent need for proper management of space traffic. , with clear communication protocols and more automation, "Krag said in an ESA article. "This is how air traffic control has been working for many decades and now space operators need to come together to determine automated coordination of maneuver."

  The designed "coupling" between Aeolus and a SpaceX satellite. "Src =" https://cdn.arstechnica.net/wp-content/uploads/2019/09/Predicted_conjunction_between_Aeolus_and_Starlink.jpg "width =" 772 "height =" 731

Engineered "connection" between Aeolus and SpaceX satellite.

Despite the paging system error, SpaceX's initial statement that it would not move its satellite apparently proved useful. "Contacting Starlink early in the process allowed ESA to take conflict-free action later, knowing the latter. the spacecraft will remain where models expect it, "ESA says.

ESA plans to automate collision avoidance

ESA said on its website that" it plans to invest in technologies needed to automatically handle collision alerts. , coordinate maneuvers with other operators, and send spacecraft commands fully automatically. "

In his communication with Forbes, Krag said that" there are no rules in space. Nobody did anything wrong. Space is there for anyone to use … Basically, you can encounter other objects in each orbit. The space is not organized. And so we believe we need the technology to manage that traffic. "

Starlink and similar broadband networks will dramatically increase the number of satellites in space, increasing the risk of space debris and collisions, as we have already written. SpaceX advertised collision avoidance technology, in May CEO Elon Musk said Starlink "will automatically maneuver around any orbital debris."

Aeolus orbits an altitude of 320 km. "Craig said it was the first collision avoidance maneuver for Aeolus since launching just over a year ago," write Cerani Space in Space. " Links are rare at this low altitude, he noted, and overall most links are debris, accounting for about 90 percent of the objects currently being traced in orbit. "

With yesterday's collision avoidance action, ESA said that his experts determined that the safest option for Aeolus was to increase its height to go over te SpaceX satellite. ESA said that he had completed the maneuver "about 1/2 orbit before the potential collision", raising Aeolus's height by 350 meters.

ESA warned that today's manual collision – the avoidance system "would become impossible "As thousands of new satellites are deployed by Starlink and other broadband clusters." Collision avoidance maneuvers it takes a lot of time to prepare – from determining the future orbital positions of a functioning spacecraft to calculating the risk of a collision and the many possible outcomes of different actions, "said ESA.

But ESA has

" ESA is preparing to automates this process using artificial intelligence, "says the agency ." From the initial assessment of a potential collision to an off-road satellite, automated systems are in place to protect our space infrastructure. "


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