More and more satellites come close to crashing because of Starlink

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We don’t really notice it from Earth, but there’s starting to be a lot of spacecraft and space debris in Earth’s orbit. Result? As on a congested road, the risk of collision increases as other vehicles enter it. Among them are the thousands of minisatellites from SpaceX’s Starlink project, the number of which continues to grow. Each week they are involved in about 1600 (also) close encounters with spaceships!

According to an article by Nature, more than 29,000 satellites, chunks of rockets and other debris large enough to be tracked from the Earth’s surface are currently in orbit around the planet; the smallest number of debris in millions. As part of the Starlink project – which aims to bring high-speed internet access to any region of the world – SpaceX has launched around 1,700 satellites in the last 2 years; the company plans to add thousands more.

More and more countries and companies are launching or planning to launch satellites. The various operators must be increasingly vigilant to avoid accidents. The situation was recently reported by Hugh Lewis, head of the Astronautical Research Group at the University of Southampton, UK. on your Twitter account. This European space debris specialist makes regular estimates of the orbital situation, using data from the SOCRATES database (Satellite Orbital Conjunction Reports Assessing Threatening Encounters in Space). It turns out that the risk of collision has been steadily increasing since the first launches of Starlink satellites in May 2019.

Eventually, Starlink will be involved in 90% of conjunctions below 1 km

The SOCRATES database, managed by Celestrack, provides a wealth of information about satellite orbits and models their future trajectories to assess collision risk. Encounters considered “close” are those that involve two satellites crossing one kilometer or less apart. Last month, nearly 500 of those encounters involved Starlink satellites each week; OneWeb, a competing company that is developing its own constellation, is involved in 80 weekly meetings:

These numbers only consider reconciliations between a Starlink or OneWeb satellite and another operator. If we add up the connections between two Starlink satellites, the number rises to 1600 per week! ” I reviewed data since May 2019 […]. Since then, the number of encounters recorded by the Socrates database has more than doubled and we are now in a situation where Starlink accounts for half of all encounters. warns Luis.

Number of weekly conjunctions of less than one kilometer predicted by SOCRATES, with (in black) and without (in grey) the satellites of the Starlink network. © Hugh Lewis/Twitter

That doesn’t bode well for the future, considering SpaceX plans to keep 12,000 total satellites for Starlink. If the company hits its target, Lewis’ calculations suggest that the Starlink network’s satellites will be involved in 90% of all conjunctions within a kilometer—to date, they are involved in 60% of them.

More and more complex predictions to make

It is mainly the satellite operators that will bear the brunt of this increase in traffic. Siemak Heser, CEO and co-founder of Kayhan Space – a company that develops a commercial autonomous space traffic management system – estimates that, on average, an operator managing 50 satellites will receive up to 300 official conjunction alerts every week. Of those 300 alerts, about ten will undoubtedly require operators to perform evasive maneuvers, maneuvers that require fuel, time and a lot of effort; however, decision making is not always obvious when weighing costs and risks.

Kayhan Space’s solution is based on data provided by the United States Space Surveillance Network, whose function is to list and track all man-made objects orbiting the Earth. It currently tracks around 30,000 operational and non-functional satellites, as well as debris as small as four inches. But as detection instruments improve and detect smaller and smaller objects, and as the number of satellites increases, the surveillance network catalog becomes increasingly dense.

Project managers are instructed to inform NASA in the event of a likely collision with the ISS or any other satellite, but the installed system may not be agile enough (in the computational sense of the term):” The processes currently in place are very manual, not scalable, and there is not enough information sharing between parties that could be affected in the event of a collision. “, underlines Heser.

Debris caused by a collision between two objects can actually create a “snowball” effect when hitting multiple other machines in its path. The collision that occurred between the American telecommunications satellite Iridium 33 and the Russian military satellite Kosmos-2251 in February 2009 – considered the worst space collision in history – generated more than 1000 pieces of debris larger than 10 cm, many of which were involved in other later orbital incidents. China’s Yunhai 1-02 weather satellite, which disintegrated in March this year, was also hit by space debris.

SpaceX relies on an autonomous collision avoidance system to ensure none of its satellites come close to other spacecraft. But, ironically, this leads to other problems: These small automatic adjustments alter the predicted orbital path and make collision predictions more complicated. ” This causes problems for everyone, because no one knows where a satellite will be or what it will do in the next few days. concludes Luis.


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