Kosmos 96
From Spacefaring
Kosmos 96, or 3MV-4 No.6, was a Soviet spacecraft intended to explore Venus. A 3MV-4 spacecraft launched as part of the Venera programme, Kosmos 96 was to have made a flyby of Venus. However, due to a launch failure, it did not depart low Earth orbit. Its re-entry into Earth's atmosphere is often speculated as the cause of the Kecksburg UFO incident.