Cosmos 381 (Russian: Космос 381) artificial satellite provided data on the physical characteristics of the layers of the Earth's Ionosphere using a Mayak radio transmitter.

The study covered almost the entire global surface.

[3] The satellite was launched into a Low Earth Orbit by a Kosmos-3 rocket (11K65M) from the LC–132/2 starting point at Plesetsk Cosmodrome on the 2nd of December, 1970.

Decay into the Earth's atmosphere is expected after about 1,200 years.

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