Kosmos 186 and Kosmos 188

Kosmos 186 (Russian: Космос-186 meaning Cosmos 186) and Kosmos 188 (respectively, Cosmos 188) were two unmanned Soviet spacecraft that incorporated a Soyuz programme descent module for landing scientific instruments and test objects. The two USSR spacecraft made the first fully automated space docking in the history of space exploration on October 30, 1967. Mutual search, approach, mooring, and docking were automatically performed by the IGLA-system on board Kosmos 186. After 3.5 h of joint flight, the satellites parted on a command sent from the earth and continued to orbit separately. Both made a soft landing in a predetermined region of the USSR - Kosmos 186 on October 31, 1967 and Kosmos 188 on November 2, 1967.

Because of the lethal outcome of both the Soyuz 1 and the US Apollo 1 missions earlier that year it was decided to proceed with unmanned flights first. But because the USSR had no ground stations outside its own territory, this meant the docking had to be done fully automated. After the first attempt failed (a fly-by at a distance of 900 m), the second attempt succeeded over the South Atlantic. However, this docking was not entirely successful either - the modules were mechanically docked, but not electrically. Also, the manoeuvre had cost more fuel than anticipated.

This mission proved it possible to launch smaller parts and assemble them in space, thus eliminating the need for exceedingly large rockets for larger undertakings like a space station.

References

Text comes from NASA NSSDC Master Catalog