Zvezda (Russian: Звезда́, meaning "star"), DOS-8, also known as the Zvezda Service Module, is a component of the International Space Station. It was the third module launched to the station, and provides all of the station's life support systems, some of which are supplemented in the USOS, as well as living quarters for two crew members. It is the structural and functional center of the Russian portion of the station - the Russian Orbital Segment.The basic structural frame of Zvezda, known as "DOS-8", was initially built in the mid-1980s to be the core of the Mir-2 space station. This means that Zvezda is similar in layout to the core module (DOS-7) of the Mir space station. It was in fact labeled as "Mir-2" for quite some time in the factory. Its design lineage thus extends back to the original Salyut stations. The space frame was completed in February 1985 and major internal equipment was installed by October 1986.The module was manufactured by RKK Energia, with major sub-contracting work by GKNPTs Khrunichev. Zvezda was launched on a Proton rocket on July 12, 2000 and docked with the Zarya module on July 26.