Kosmos 2609-2616

Maiden flight of the Soyuz-2.1b / Volga combination - the first time the restartable Volga upper stage was paired with the more powerful 2.1b variant. The Volga had previously flown exclusively with the lighter Soyuz-2.1v, which was retired in February 2025.

The Volga performed a plane-change burn to distribute the satellites across two slightly different sun-synchronous orbital planes. Insufficient propellant remained after the maneuver for the stage's usual deorbit burn, leaving it in an uncontrolled orbit.