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Functional Cargo Block (FGB) Zarya

Zarya («Заря», “dawn”), the first module of the ISS was launched on 20 November 1998 by a Proton-K rocket. It was developed by GKNPTs M.V. Khrunichev in Moscow, Russia under a subcontract to the Boeing company. The module is thus Russian-built and U.S.-funded. Construction was begun in 1994.

FGB Zarya initially provided flight control when it was docked with Unity, as well as electricity and fuel supplies. It had enough heptyl fuel (4.5 metric tonnes) to keep it in orbit for 430 days without refuelling.

After the Zvezda Service Module reached orbit, Zarya was relegated to back-up life support and used for storage, many of its functions taken over by the Service Module. The FGB has a lifetime of at least 15 years from its launch.

Zarya computer illustration (ESA)


Zarya is comprised of two main components:

  • The cylindrical instrument-cargo section ( PGO, РГО – приборно-грузовой отсек), itself divided into 3 sections:
    • PGO-2 (conical section of the FGB);
    • PGO-3 (the GA cylindrical section)
    • and PGO-1 (lies between the former two sections);
  • the spherical airtight adapter (GA, ГА – гермоадаптер) which provides docking connections.

An 800 mm-diameter hatchway connects the PGO and GA sections. The GA has 7.0 m³ of airtight volume; the PGO has 64.5 m³. Both segments are divided into an instrument zone (for various equipment) and habitable zone (for the crew). The instrument zone contains control systems and alarms, and is isolated from the habitable zone by panels.

The FGB has 90 storage lockers along its main corridor, in which supplies and various equipment are kept. Panel numbering in the PGO from forward – the GA, Pressurized Adapter – to aft (where Zvezda is attached):

  • Plane I (floor): Panels from 101 to 116.
  • Plane II (port): Panels 201 to 231.
  • Plane III (ceiling): Panels 301 to 316.
  • Plane IV (starboard): Panels 401 to 431.

Zarya has 3 docking assemblies. On the front end of the PGO (facing aft in the ISS layout) is located the active hybrid docking assembly, ASA-G, АСА-Г, and it is docked to the Zvezda Service Module. The rear end of the GA (forward in the ISS layout) is equipped with a passive androgynous docking assembly (АСПП, ASPP) which enables it to be docked with Pressurized Mating Adapter-1 of the U.S. segment. Also on the GA is a passive cone docking assembly perpendicular to the longitudinal X-axis of Zarya, where Soyuz and Progress ships can dock (it faces “down” towards Earth).

Three types of engines were used by Zarya:

  • Correction and approach (ДКС, DKS). There are two of these liquid propellant 11D442 rocket engines that were used by the ship to correct its orbit during autonomous flight. These are the main engines, used for large maneuvers.
  • Approach and stabilization engines (ДПС, DPS). There are 24 of these 11D458 liquid propellant rocket engines that can do 8 repeated firings.
  • Precision stabilization engines (ДТС, DTS). There are 16 liquid propellant 17D58E engines that were used for the precision approach to the Orbiter STS-88. These have the smallest thrust.

The engines were decommissioned after Zvezda was launched and its systems activated.

Zarya’s fuel system stores and supplies fuel to the engines, and comprises a fuel (nitric tetraksid) and a combustible (unsymmetrical dimethylhydrazine), stored in 16 fuel tanks (8 fuel, 8 oxidizer) and totalling 6100 kg. It can be resupplied via Progress cargo ships. It is divided into two subsystems: high pressure and low pressure. The latter supplies the low-thrust engines (DPS and DTS). 5 fuel and 5 oxidizer tanks are high-pressure; the remainder are low-pressure. Zarya was launched with partially-full tanks of 3800 kg.

Zarya derives its power from two solar arrays (СБ, SB), each 28 m² (7 m long and 4 m wide) and covered on one side with glass-coated photoelectric converters; these were unfurled upon reaching orbit. The cells absorb 90% of sunlight on the side facing the sun, and 10% of reflected sunlight from Earth on their reverse sides. Power was transferred to 6 batteries in the power supply system (SES, СЭС) which, in the initial stages, supplied power to the FGB and Unity. Later after the arrival of Zvezda, Zarya converted power from the U.S. segment (124 V dc) for use in the Russian segment (28 V dc).

Zarya’s systems are divided into a support section and Station section. The support section helped Zarya function during autonomous flight and docking; the Station section helps the FGB interact with the rest of the ISS.

The support section comprises:

  • the control system, система управления (СУ, SU);
  • engine installation, двигательная установка (ДУ, DU);
  • the feed system and pumping of fuel, система подачи и перекачки топлива (СПиПТ, SPiPT);
  • onboard complex control system, система управления бортовым комплексом (СУБК, SUBK):
  • internal lighting system, система внутреннего освещения (СВО, SVO);
  • “Komparus” control-measuring system, командно-измерительная система (КИС, KIS);
  • the BR-9TsU-8 radiotelemetry system, радиотелеметрическая система БР-9ЦУ-8;
  • the Sirius-4 radiotelemetry system, радиотелеметрическая система «Сириус-4»;
  • power supply system, система электроснабжения (СЭС, SES);
  • the orientation system for the solar batteries, система ориентации солнечных батарей (СОСБ, SOSB);
  • thermal control system , система обеспечения теплового режима (СОТП, SOTP);
  • fire detection and fire extinguishing system, система пожарообнаружения и пожаротушения (СПоПТ, SPoPT);
  • Kurs-A, «Курс-А» active radio-technical rendezvous and docking system.

The Station section comprises:

  • docking system, система стыковки (СС, SS);
  • the integration and joining/docking system, система интеграции и сопряжения (СИС, SIS);
  • a system for assuring proper gas composition (atmosphere revitalization subsystem), система обеспечения газового состава (СОГС, SOGS);
  • television system, система телевидения (СТ, ST);
  • telephone communications system, система телефонной связи (СТС, STS);
  • communications/message acquisition equipment, аппаратура сбора сообщений (АСС, ASS);
  • onboard computing system, бортовая вычислительная система (БВС, BVS);
  • teleoperator mode of control equipment (ТОРУ, оборудование телеоператорного режима управления, TORU) of approach and docking;
  • passive radio-technical rendezvous and docking system “Kurs-P”, пассивная радиотехническая система сближения и стыковки «Курс-П»

Data tables

Zarya: fundamental technical characteristics
Mass in orbit, kg 20 040
Length of housing, mm 12 990
Maximum diameter, mm 4100
Volume of airtight sections, cubic meters 71.5
Spread of solar batteries, mm 24 400
Area of photovoltaic cells, meters squared 28
Average power of power supply, KVT/SUT 3
Fuel mass, kg 3800
Duration of functioning in orbit, years 15
Zarya launch data
Designation 77KM №17501
NASA designation 1A/R
Launch vehicle Proton-K (№395-01)
Launch site Launch complex 81/23, Baikonur Cosmodrome, Republic of Kazakhstan
Launch date 20 November 1998 at 06:40
Mission Launch of the first Russian ISS module (FGB). The U.S. Unity module was docked to it during the STS-88 mission


Links to external images at the Capcom Espace website:



Photo gallery

Zarya from STS-88

A nadir (bottom) view of Zarya, taken during the STS-88 mission, 6 December 1998. The cylindrical Pressurized Adapter (GA, ГА) is at the bottom of the picture.

Dezhurov in Zarya

Vladimir Dezhurov (ISS-3) in Zarya’s main corridor, at the forward end. Port is on the left of the picture; starboard on the right. The storage lockers are visible.