Kosmos 277
Introduction '''Kosmos 277''' ( meaning ''Cosmos 277''), known before launch as '''DS-P1-Yu No.20''', was a Soviet satellite which was used as a radar calibration target for tests of anti-ballistic missiles. It was a  spacecraft, which was built by the Yuzhnoye Design Bureau, and launched in 1969 as part of the Dnepropetrovsk Sputnik programme.
Launch Kosmos 277 was launched from Site 133/1 at the Plesetsk Cosmodrome, atop a Kosmos-2I 63SM carrier rocket. The launch occurred on 4 April 1969 at 13:00:04 UTC, and resulted in Kosmos 277's successful deployment into low Earth orbit. Upon reaching orbit, it was assigned its Kosmos designation, and received the International Designator 1969-033A.Kosmos 277 was operated in an orbit with a perigee of , an apogee of , 70.9 degrees of inclination, and an orbital period of 91.2 minutes. It remained in orbit until it decayed and reentered the atmosphere on 6 July 1969.It was the twentieth of seventy nine DS-P1-Yu satellites to be launched, and the nineteenth of seventy two to successfully reach orbit.
See also *1969 in spaceflight
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