A pair of Russian military satellites passed within 3 metres of each other last week in an unexplained manoeuvre high above Earth, a close approach tracked by US-based space situational awareness firm COMSPOC. The craft, COSMOS 2581 and COSMOS 2583, were launched by Russia's space agency Roscosmos in February 2025 and were flying at an altitude of about 585 kilometres when they moved into the tight configuration.
COMSPOC said it saw what it described as a complex proximity event involving Russian satellites, and said COSMOS 2583 carried out several fine manoeuvres to hold the formation. The company said on May 1, 2026, that the pass was not accidental. “This wasn’t a coincidental pass – COSMOS 2583 performed several fine manoeuvres to maintain this tight configuration... Whatever Russia is testing, it’s sophisticated,” it said.
The satellites have not been publicly identified by Russia beyond their COSMOS designations, but space analysts say one of them released a sub-satellite known as Object F. The pair are believed to be part of a program involving inspector satellites, spacecraft designed to test or carry out surveillance operations on other satellites in orbit. That has kept attention on Moscow's intentions in orbit, especially because Russia has never disclosed the specific purpose of the craft.
Dean Sladen said the episode was unusual not because satellites sometimes fly close together, but because these were free-flying craft with no docking hardware or shared guidance system. “From a precision-engineering perspective, this is genuinely impressive, but close-proximity operations are not unusual,” he said. “Every crewed and cargo vehicle bound for the International Space Station carries out similar manoeuvres, with spacecraft far larger than these satellites docking within metres of the station on a monthly basis.”
He said the difference was that the COSMOS manoeuvre happened between two independent satellites, and that the closing rates were likely higher than those used by spacecraft approaching the International Space Station. “Satellites in low Earth orbit typically travel at roughly 8 kilometres per second. Everything has to be handled by onboard guidance systems running thousands of calculations a second, with manoeuvre decisions made autonomously inside tight time windows,” Sladen said. “When that control loop works, the precision and granularity are extraordinary. That said, when it doesn't, a single miscalculation can turn two intact spacecraft into thousands of high-velocity fragments capable of disabling anything they strike.”
The concern reaches beyond this one pass. Nearly half of all tracked objects in Earth's orbit are space junk, according to Accu Components' recent debris report, and a collision between two satellites in low Earth orbit could add to the cloud of fragments known as the Kessler syndrome. That is why close inspection missions, even when they are technically impressive, are watched so closely: a brief orbital dance can end as debris that lasts for years.
For now, the unanswered question is not whether the satellites can fly this close, but what Russia is rehearsing with them in the first place.