The Polyus spacecraft (, pole), also known as Polus, Skif-DM, GRAU index 17F19DM, was a prototype Soviet orbital weapons platform designed to destroy Strategic Defense Initiative satellites with a megawatt carbon-dioxide laser. It had a Functional Cargo Block derived from a TKS spacecraft to control its orbit and it could launch test targets to demonstrate the fire control system. History The Polyus spacecraft was launched 15 May 1987 from Baikonur Cosmodrome Site 250 as part of the first flight of the Energia system, but failed to reach orbit. According to Yuri Kornilov, Chief Designer of the Salyut Design Bureau, shortly before Polyus' launch, Mikhail Gorbachev visited the Baikonur Cosmodrome and expressly forbade the in-orbit testing of its capabilities. Kornilov claims that Gorbachev was worried that it would be possible for Western governments to view this activity as an attempt to create a weapon in space and that such an attempt would contradict the country's previous statements on the USSR's peaceful intent. For technical reasons, the payload was launched upside down. It was designed to separate from the Energia, rotate 180 degrees in yaw, then 90 degrees in roll and then fire its engine to complete its boost to orbit. The Energia functioned perfectly. However, after separation from Energia, the Polyus spun a full 360 degrees instead of the planned 180 degrees. When the engine fired, it slowed and burned up in the atmosphere over the south Pacific Ocean. This failure was attributed to a faulty inertial guidance system that had not been rigorously tested due to the rushed production schedule. Parts of the Polyus project's hardware were re-used in Kvant-2, Kristall, Spektr and Priroda Mir modules, as well as in the ISS modules Zarya and Nauka. Development NPO Energia received orders from the Soviet government to begin research on space-based strike weapons in the mid-1970s. Even before, the USSR had been developing maneuverable satellites for the purpose of satellite interception. By the beginning of the 1980s, Energia had proposed two programs: laser-equipped Skif and guided missiles platform Kaskad (where Skif would cover the low-orbit targets, Kaskad engaged targets in high and geosynchronous orbits). Together with NPO Astrofizika and KB Salyut, they began developing their orbital weapons platform based on the Salyut DOS-17K frame. Later, when the objective of ICBM interception proved too difficult, the aims of the project were shifted towards anti-satellite weapons. The 1983 announcement by the US of