Russian Orbital Segment

The segment currently consists of six modules, which together essentially comprise the base configuration of the cancelled Russian space station Mir-2. The segment is controlled directly from Roskosmos's Mission Control Center in Moscow. The six modules are (in order of launch): The first module, Zarya, otherwise known as the Functional Cargo Block or FGB, was the first component of the ISS to be launched, and provided the early station configuration with electrical power, storage, propulsion, and navigation guidance, until a short time after the Russian service module Zvezda docked and control was transferred. Zvezda contains the ESA built DMS-R Data Management System. Now primarily used for storage, Zarya provides ports for Soyuz and Progress spacecraft and the European ATV to dock to the station. Ships boosting the station's orbit dock to the aft port (the rear port according to the station's normal orientation and direction of travel). The FGB is a descendant of the TKS spacecraft designed for the Russian Salyut program. 5.4 tons of propellant fuel can be stored and transferred automatically to and from ships docked.