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A satellite owned by the European Space Agency (ESA) has had to dodge out of the way of another satellite. The latter of the two is part of the huge constellation of satellites SpaceX is putting in orbit to facilitate wireless internet access. Aside from being bad publicity for Elon Musk’s firm, the incident also raises critical questions about whether we need clearer rules on navigation as the number of objects in orbit soars.

The near miss happened on the morning of 2 September, as the ESA’s Aeolus satellite, which monitors wind patterns, was orbiting 320 kilometres above Earth. In May, Starlink launched a batch of 60 satellites, and one of these, Starlink 44, veered dangerously close to Aeolus. According to ESA, the risk of collision was one in 1000, which is 10 times higher than the one in 10,000 risk that necessitates a collision avoidance manoeuvre. SpaceX puts the risk even higher, at one in 591.

While the ESA says it was not perturbed by the incident, the lack of communication from SpaceX caused unnecessary uncertainty. The firm failed to correspond with the agency during the five days in this run up to the incident, apart from one email early on when the risk of collision was still just one in 50,000. SpaceX blamed this on a “bug in our on-call paging system”. Because of this, the agency was forced to fire Aeolus’ thrusters to take evasive action.

In a situation like this, there are no laws on how each operator should act. Instead, the safe resolution of situations like these – which are not unheard of – relies on goodwill communication between the operators to clarify who will move. Technically, neither SpaceX nor the ESA did anything wrong.

“It highlights that the current mostly ad-hoc system probably is not suitable for where we’re going to be in the next few years,” says Brian Weeden at the space advocacy organisation Secure World Foundation. “At the moment it’s kind of up to every operator to do what they think is best.”

Incidents like this are probably only going to become more likely. SpaceX has plans to launch a total of 12,000 Starlink satellites into orbit. And it’s not alone. Other companies, including Amazon, OneWeb and Kepler Communications, are also working to create mega constellations, with more than 20,000 satellites planned in all. That’s a gigantic increase on the 2000 active satellites orbiting Earth today.

Rules of the road

It’s all too apparent that our archaic rules, based largely on 1967’s Outer Space Treaty, cannot cope with this increase. Space consultant Rand Simberg, however, says he is in the process of working with the US government to update these rules. “The goal is to try right now to develop some customary laws and norms,” he says. “I’m hoping that within the next few months we’ll actually have some draft language.”

The major challenge will be getting other countries and companies to agree to any new rules or regulations in space. “I wouldn’t want government to impose rules of the road regulation,” says Tim Maclay, OneWeb’s director of mission systems engineering. “It could be that we get to a point where that kind of a structure is necessary, but I don’t think we’re there yet.”

For others, however, time is of the essence to get rules in place soon as more mega constellations like Starlink start to come to fruition. “We’ve never seen constellations this large before,” says Weeden. At the most basic level, deciding who has right of way could be crucial.