Astronomers have observed two Russian military satellites passing within three metres of each other in a sophisticated but unexplained manoeuvre. The COSMOS 2581 and COSMOS 2583 satellites, launched by Roscosmos in February 2025, performed the operation last week at an altitude of around 585 kilometres.
The incident, tracked by US-based firm COMSPOC, has raised concerns about space-based surveillance and orbital collisions. “This wasn’t a coincidental pass – COSMOS 2583 performed several fine manoeuvres to maintain this tight configuration,” COMSPOC said. “Whatever Russia is testing, it’s sophisticated.”
Russia has not disclosed the satellites’ purpose, but space analysts believe they are part of an “inspector satellite” programme designed to test or perform surveillance of other spacecraft. One of the satellites released a sub-satellite referred to as Object F.
Dean Sladen, an aerospace engineer at Accu Components, described the precision as “genuinely impressive” but noted that close-proximity operations are not unusual. “The difference is this took place between two free-flying satellites without docking mechanisms, and the closing rates were likely higher,” he said.
The manoeuvre also highlights risks of space debris. Accu Components’ recent report found that nearly half of all tracked objects in orbit are space junk. A collision could trigger Kessler syndrome, creating an impenetrable debris layer. Sladen warned that a single miscalculation could turn two spacecraft into thousands of high-velocity fragments.
