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Biktimirov and his team say the descent of the satellites and any potential collisions could be monitored, but some are sceptical of how accurately this could be done. “The debris is especially concerning, given that tracking objects and satellites across a range of sizes and orbital parameters is inherently challenging and is affected by many factors including solar storms,” says Aparna Venkatesan at the University of San Francisco, California.

The only way to really mitigate this risk is by taking the satellites down as soon as they stop functioning, says John Crassidis at the University of Buffalo in New York. “Until there is a mandate to immediately remove the satellites once their formation is no longer maintained, then they will be a problem,” he says.

As well as the risk from debris, the reflected light could interfere with important telescopes, both on Earth and in space, including asteroid monitoring systems. “Astronomy already contends with the interference from the thousands of satellites already in orbit and faces a future in which that number may be as much as 100 times higher than it is now within a decade. Space advertising will only make this worse,” says Barentine.