Kosmos 166

Kosmos 166 (Космос 166 meaning Cosmos 166), also known as DS-U3-S No.1, was a satellite which was launched by the Soviet Union in 1967 as part of the Dnepropetrovsk Sputnik programme. It was a 400 kg spacecraft, which was built by the Yuzhnoye Design Office, and was used to conduct multispectral imaging of the Sun.

Kosmos 166 was launched from Site 86/1 at Kapustin Yar, aboard a Kosmos-2I 63SM carrier rocket. The launch occurred at 04:44:00 GMT on 16 June 1967, and resulted in the successful insertion of the satellite into a low Earth orbit. Upon reaching orbit, the satellite was assigned its Kosmos designation, and received the International Designator 1967-061A. The North American Air Defense Command assigned it the catalogue number 02848.

Kosmos 166 was the first of two DS-U3-S satellites to be launched, the other being Kosmos 230. It was operated in an orbit with a perigee of 281 km, an apogee of 553 km, an inclination of 48.4°, and an orbital period of 92.6 minutes. It completed operations on 26 September 1967, before decaying from orbit and reentering the atmosphere on 25 October.