At 4 a.m. on September 20, 1977, a massive luminous jellyfish-shaped object hovered over Petrozavodsk, Karelia, for twelve minutes, emitting radial light beams that left melted holes in factory windows. Witnesses included paramedics, air traffic controllers, sailors, and a TASS correspondent.

The Soviet Academy of Sciences gathered 85 formal reports by December 1978. A clinical psychologist evaluated nine witnesses and certified their 'complete mental sanity.' TASS journalist Nikolai Milov reported people felt electric sensations during the beam phase. The Academy's preliminary finding was that available data made it 'unfeasible to satisfactorily understand the observed phenomenon.' The incident directly triggered creation of the twin SETKA programs in 1978. James Oberg later attributed the event to the Plesetsk launch of Cosmos-955, but witnesses noted the object moved westward while the satellite launched northeast.