Kosmos 277 (Russian: Космос 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 325-kilogram (717 lb) spacecraft, which was built by the Yuzhnoye Design Bureau, and launched in 1969 as part of the Dnepropetrovsk Sputnik programme.