Docking target craft for Cosmos 186, which achieved world's first automatic rendezvous on second attempt. Capture achieved but hard docking and electric connections unsuccessful due to misallignment of spacecraft. Ion flow sensor failed and Cosmos 188 had to make a high-G uncontrolled re-entry. When it deviated too far off course, destroyed by the on-board self-destruct system, November 2, 1967 09:10 GMT.
Officially: Investigation of outer space, development of new systems and elements to be used in the construction of space devices.

Cosmos 186 was followed on 30 October by Cosmos 188, (the passive spacecraft - 7K-OK(P) s/n 5, the spacecraft that was to have flown the Soyuz 2 mission in April 1967). The passive spacecraft was placed in the planned orbit, only 24 km from Cosmos 186, and an automatic first orbit rendezvous and docking was attempted. The first docking attempt failed when the active spacecraft flew past Cosmos 188 at a distance of 900 m after the system lost contact. The spacecraft set itself up for a second attempt and achieved soft-dock. However when hard-dock was attempted an excessive lateral movement led to the directional steering of the active spacecraft torquing, and the detailed interface latches and connectors of the docking rings did not join. The spacecraft had hard docking but without full latching and electrical connections. There was also a significant over-expenditure of propellant in the docking process.

After problems with the star tracker on Cosmos 186, Cosmos 188 attempted retrofire and re-entry using the ion flow sensor - but this also failed. The capsule returned on an uncontrolled trajectory. When the APO destruct system determined that the course had exceeded allowable parameters, the capsule was destroyed by explosive charge high over Irkutsk (until 1999 this spacecraft had been reported to have been successfully recovered). References: 1 , 2 , 6 .