First module of the International Space Station
Zarya (), also known as the Functional Cargo Block (), is the inaugural component of the International Space Station (ISS). Launched on 20 November 1998 atop a Proton-K rocket, the module would serve as the ISS's primary source of power, propulsion, and guidance during its early years. As the station has grown, "Zarya"'s role has transitioned primarily to storage, both internally and in its external fuel tanks. A descendant of the TKS spacecraft used in the "Salyut" programme, "Zarya" was built in Russia but its construction was financed by the United States. Its name, meaning "sunrise," symbolizes the beginning of a new era of international space cooperation.
Construction.
The Zarya design was originally intended as a module for the Russian "Mir" space station, but was not flown as of the end of the Mir program. A FGB cargo block was incorporated as an upper stage engine into the Polyus spacecraft, flown (unsuccessfully) on the first Energia launch. With the end of the Mir program, the design was adapted to use for the International Space Station.
The "Zarya" module is capable of station keeping and provides sizable battery power; it was suggested to have initially been built to both power and control the recoil from a further derivation of the then classified Skif laser system/Polyus satellite. Commentators in the West thought that the "Zarya" module was constructed more cheaply and lifted to orbit faster than should have been possible in the post-Soviet era, and that the FGB might have been largely constructed from mothballed hardware from the Skif laser program (which had been canceled after the failed 1987 Polyus launch).
The research and development of a similar design was paid for by Russia and the Soviet Union; the design of the module and all systems are Soviet/Russian. The United States funded "Zarya" through the U.S. prime contracts in the 1990s as the first module for ISS, and it was built from December 1994 to January 1998 in Russia at the Khrunichev State Research and Production Space Center (KhSC) in Moscow. The module was included as part of NASA's plan for the International Space Station (ISS) instead of Lockheed Martin's "Bus-1" option because it was significantly cheaper (US$220 million vs. $450 million). As part of the contract, Khrunichev constructed much of an identical module (referred to as "FGB-2") for contingency purposes. FGB-2 was proposed to be used for a variety of projects; it has been used to construct the Russian Multipurpose Laboratory Module "Nauka".
Design.
"Zarya" has a mass of , is long and wide at its widest point.
The module has three docking ports: one axially on the front end at the docking sphere, one on the Earth-facing side (nadir) of the docking sphere and one axially on the aft end.
Attached to the forward port is the Pressurized Mating Adapter "PMA-1", which in turn is connected to the "Unity" Module – this is the connection
between the Russian Orbital Segment (ROS) and the US Orbital Segment (USOS).
Attached to the aft port is the "Zvezda" Service Module. The lower port (nadir) was initially used by visiting Soyuz spacecraft and Progress spacecraft to dock to the ROS; The "Rassvet" module is now docked semipermanently on the nadir port of "Zarya", and visiting spacecraft use "Rassvet"'s nadir docking port instead. It was planned to install another zenith docking port in the docking sphere, however, after the design was changed, a spherical cover was welded in its place.
"Zarya" has two solar arrays measuring and six nickel-cadmium batteries that can provide an average of of power – the solar arrays have been however partially retracted so the P1/S1 radiators of the Integrated Truss Structure could deploy. They are still generating some power, but not the average of power, they once provided when they were fully unfurled. "Zarya" has 16 external fuel tanks that can hold up to of propellant (this requirement was mandated by NASA in early 1997 over concerns that the "Zvezda" Service Module would be further delayed, hence the FGB had to be capable of independent propellant storage and transfer from Progress spacecraft even without "Zvezda" ). "Zarya" also has 24 large steering jets, 12 small steering jets, and two large engines that were used for reboost and major orbital changes; with the docking of "Zvezda" these are now permanently disabled. Since they are no longer needed for "Zarya"'s engines, Zarya's propellant tanks are now used to store additional fuel for "Zvezda".
Launch and flight.
"Zarya" was launched on 20 November 1998 on a Russian Proton rocket from Baikonur Cosmodrome Site 81 in Kazakhstan to a high orbit with a designed lifetime of at least 15 years. After "Zarya" reached orbit, STS-88 launched on 4 December 1998 to attach the "Unity" module.
Although only designed to fly autonomously for six to eight months, "Zarya" was required to do so for almost two years due to delays to the Russian Service Module, "Zvezda". "Zvezda" was finally launched on 12 July 2000, docking with "Zarya" on 26 July 2000.
"Zarya" passed the 50,000-orbit mark at 15:17 UTC on 14 August 2007 during the STS-118 mission to the International Space Station.
References.
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