Zarya (Заря́; lit. dawn), also known as the Functional Cargo Block or the FGB (the Russian acronym for "функционально-грузовой блок"), was the first module of the International Space Station to be launched. The FGB provided electrical power, storage, propulsion, and guidance to the ISS during the initial stage of assembly. As other modules with more specialized functionality are constructed, the Zarya's role will primarily be storage, both inside the pressurized section and in the externally mounted fuel tanks. The Zarya is a descendant of the TKS spacecraft designed for the Russian Salyut program. The name "Zarya", meaning "Dawn" in Russian, was given to the FGB because it signified the dawn of a new era of international cooperation in space.
Zarya has three docking ports, one on each end, and one on the side. Zvezda is attached to the aft port, the Pressurized Mating Adapter attached to the forward port connects to the Unity Module, and the side (axial or nadir) port is used to dock with either a Russian Soyuz or a Progress spacecraft, until the Docking Cargo Module is docked there permanently. Zarya has two solar arrays, measuring 10.67 m by 3.35 m, and six nickel-cadmium batteries that can provide on average 3 kilowatts of power. Zarya has 16 external fuel tanks that can hold over 6 metric tons of propellant, with 24 large steering jets, 12 small steering jets, and two large engines for reboost and major orbital changes.
Although only designed to fly autonomously for six to eight months, Zarya was required to fly autonomously for almost two years due to delays to the Russian Service Module, Zvezda. Finally, on July 12, 2000, Zvezda was launched and docked on July 26 using the Russian Kurs system.
Zarya initially had problems with battery charging circuits, but these were resolved. It will eventually require supplemental micro meteor shielding, as it was given an exemption to the ISS rules when it launched.
Zarya passed the 50,000-orbit mark at 15:17 UTC. on August 14, 2007, during the STS-118 mission to the International Space Station.