Kosmos 140

Kosmos 140 (Russian: Космос 140 meaning Cosmos 140) was an unmanned flight of the Soyuz spacecraft. It was the third attempted test flight of the Soyuz 7K-OK model, after orbital (Kosmos 133) and launch (Soyuz 11A511) failures of the first two Soyuz spacecraft. The spacecraft suffered attitude control problems and excessive fuel consumption in orbit, but remained controllable. An attempted maneuver on the 22nd orbit still showed problems with the control system. It malfunctioned yet again during retrofire, leading to a steeper than planned ballistic reentry and a 300 mm (12 in) hole being burned in the heat shield.

Although the event would have been lethal to any human occupants, the capsule's recovery systems operated and the capsule crashed through the ice of the frozen Aral Sea, hundreds of kilometers short of its landing zone. The spacecraft finally sank in 10 meters of water and had to be retrieved by divers. The test performance was nonetheless deemed "good enough"; the manned docking missions of Soyuz 1 and Soyuz 2 were approved for the next flight.