"Soyuz Completes Two-Month Endurance Mission"

From Nov. 30, 1973, to Jan. 28, 1974, the Soyuz spacecraft completed a two-month autonomous endurance mission, setting a new record for its solo flight. Originally intended for a crewed mission to the DOS-2 space station, the spacecraft was repurposed for the unpiloted test flight after the loss of DOS-3. The mission, designated Kosmos-613, involved testing the spacecraft's onboard systems in a simulated joint flight with a space station, certifying it for future expeditions. The spacecraft successfully landed on Jan. 28, 1974, and its nature was publicly acknowledged in 1985.