International Space Station – ISS – the first space station built with the participation of many countries. It consists of 43 modules and elements and allows for the simultaneous stay of seven permanent crew members (three until 2009, in practice six until 2020 due to transport limitations). The first modules of the station were launched into Earth orbit and connected to each other in 1998. The first permanent crew took up residence on it in 2000.
The power source for the ISS is solar cells; until July 19, 2011, the transport of people and materials was handled by American shuttles of the Space Transportation System (STS) (suspended from February 2003 to July 26, 2005, due to the Columbia shuttle disaster) and Russian Soyuz and Progress spacecraft. After the end of the American shuttle program in 2011, Russian Soyuz rockets became the carrier of permanent astronauts, and from 2020, the Crew Dragon American spacecraft of the American company SpaceX.
The station has radio equipment for amateur radio purposes (the ARISS project). It also has its own assigned call signs: American NN1SS and NA1SS, Russian RZ3DZR, and German DL0ISS.
George W. Bush’s administration planned to stop funding the station after 2015, which would have resulted in deorbiting the station in early 2016. However, the administration of the next US president, Barack Obama, extended the funding until 2020, and potentially even until 2028.
The station’s solar panels reflect so much sunlight that it is visible from Earth as an object moving across the sky.
Creation
The International Space Station was created as a result of combining the projects for the construction of the Russian Mir-2 station, the American Freedom, and the European Columbus. They aimed to fulfill the dream of a permanent human presence in space. This has been realized since November 2, 2000, when the first permanent crew reached the ISS, consisting of: William Shepherd, Yuri Gidzenko, and Sergei Krikalev (Soyuz TM-31 mission). Initially, the station was to be named Alpha (the first), but the Russian side opposed this, claiming that the Soviet Salyut 1 from 1971 was the first. Instead, they proposed the name „Atlant”, which in turn the Americans did not like due to its excessive similarity to the sunken Atlantis. Due to the lack of other ideas, the International Space Station still does not have its own name today.
The first plans to build a space station jointly by the United States, Japan, and the European Space Agency appeared back in the 1980s with the Freedom station project. This project was eventually abandoned in favor of building an international station. Since 1991, Canada also joined the work, and in 1993 – Russia. Unrealized concepts of the Freedom station, the Russian Mir-2 (whose planned base module, DOS-8, became an element of the Russian segment), and the European Columbus station (only the orbital laboratory module launched into orbit in 2008 was used from the project) were utilized. The project was to be implemented in three stages:
I – preparation of modules and international flights to the Russian Mir station – implemented in the years 1995–1998
II – assembly and initial operation (1998–2001)
III – completion of construction and further operation (beginning of 2001, end in 2011)
Initially, the program budget for the period from 1994 to the completion of construction was to be 17.4 billion USD, but by the time the first module was launched in late 1997, it had more than doubled to 40 billion USD. In 1998, Brazil joined the project. The first element of the station, the Russian Zarya module, was launched into orbit on November 20, 1998. By the arrival of the first crew, the ISS was enriched with two more modules – the American Unity and the Russian Zvezda.
Countries participating in the project
United States – National Aeronautics and Space Administration (NASA)
Russia – Roscosmos
Canada – Canadian Space Agency (CSA)
Members of the European Space Agency (ESA)
Belgium
Denmark – DNSC
France – Centre National d’Études Spatiales (CNES)
Spain – INTA
Netherlands
Germany – Deutsches Zentrum für Luft- und Raumfahrt (DLR)
Norway – NSC
Switzerland
Sweden – SNSB
Great Britain
Italy – Italian Space Agency (ASI)
Japan – Japan Aerospace Exploration Agency (JAXA)
Usage
The main goal of the International Space Station is to enable scientific research in microgravity conditions, impossible to achieve on Earth in a long-term way, allowing for the improvement of cultivation methods, better understanding of the functioning of organisms (and thus the possibility of inventing new drugs), and helping to solve other Earthly scientific problems.
Flights to the ISS
To date, 37 flights of American shuttles have taken place to the station (the STS program ended in 2011), 73 crewed flights of Russian Soyuz (as of July 2025), and from May 2020, Crew Dragon spacecraft of the SpaceX company have been traveling to the station. Since 2000, the ISS has been supplied by Russian Progress M cargo shuttles, in April 2008 the ATV – a transport vehicle constructed by ESA – docked to the station for the first time, in September 2009 the first flight of the Japanese HTV took place, and since October 2012 the station has also been supplied by Dragon cargo spacecraft.
In 2020, Soyuz-MS-17, launching from the Baikonur cosmodrome, reached the ISS in a record time of about 3 hours.
Permanent crews
Starting from 1998, 170 people stayed on the ISS, of which 50 were members of permanent crews within 20 expeditions. For comparison – the Russian Mir station was visited by a total of 137 people over 14 years. Almost 1/4 of all astronauts were the crew of the International Space Station or the vehicles serving it.
Space tourists
In 2001, the first space tourist in history visited the ISS. American millionaire Dennis Tito paid 20 million dollars for nearly eight days (7 days, 22 hours, 4 minutes) of stay in space from April 28 to May 6. The second tourist was Mark Shuttleworth from South Africa. The third tourist was Gregory Olsen in 2005, who flew to the International Space Station despite poor health. The first female space tourist was an American of Iranian descent, Anousheh Ansari. The initial candidate for the Soyuz TMA-9 flight, Daisuke Enomoto, was removed for medical reasons.
The ISS was also the site of the first space wedding. On August 10, 2003, Russian cosmonaut Yuri Malenchenko married Ekaterina Dmitriva, who was in Texas at the time.
On September 30, 2009, aboard the Soyuz TMA-16 spacecraft, Canadian Guy Laliberté went to the International Space Station as the seventh space tourist. He paid 35 million dollars for his flight.
Station modules
The station consists of 16 basic pressurized modules, with a total volume of about 1000 m³. These are laboratory, docking, airlock, and connector modules. Currently. They were launched into orbit using shuttles, as well as Proton or Soyuz rockets.
Zaria – the first module of the International Space Station, belonging to the Russian part of this station. It was built from December 1994 to January 1998 by Russia, but the United States was responsible for financing the work. Zaria, in the initial period of station construction, provided electricity, stabilization, maneuvers, and communication. Currently, after its role was taken over by the Zvezda module, it serves as a warehouse and a propellant tank.
Unity (Node 1) – the first component of the International Space Station built by the United States. It was launched into orbit on December 4, 1998, as the primary payload of the shuttle mission STS-88 – assembly flight 2A. It serves as a connecting corridor between, among others, the station’s modules; it is cylindrical in shape; it has six passages (nodes).
Node 1 was built by the Boeing Company at the Marshall Space Flight Center production facility in Huntsville, Alabama. Unity is the first of three connector modules built for the station’s needs.
Delivered to orbit aboard the shuttle Endeavour, Unity was connected on December 6, 1998, to the already orbiting Zaria module (a station component financed by the United States and built by Russia), which had been launched earlier aboard a Proton rocket from the Baikonur Cosmodrome (Kazakhstan). Additionally, connected to Unity are:
Destiny laboratory,
Node 3,
a truss structure holding the early solar panel system – Integrated Truss Structure ITS Z1,
Quest airlock.
Essential station resources – such as fluids, environmental control and life support systems, electrical and data systems – run through Unity, providing the supply necessary for life and work on the ISS. Inside the module, there are over 50,000 mechanical parts, 216 lines for fluids and gases, and 121 electrical cables (internal and mounted on the outer hull) with a total length of over 11 kilometers. Node 1 has four special equipment racks and is also equipped with a communication system enabling the transmission of data, voice, and low-quality video signals between the ISS and the Mission Control Center in Houston, used in the early stages of the station’s operation. The construction of the module is based on an aluminum frame.
Zwiezda – the service module of the International Space Station belonging to the Russian part of the station. It was the first fully Russian element of the station (the second Russian module, Zaria, was financed by NASA). It was initially designed and built as DOS-8 – the main module of the planned Mir-2 space station, the successor to the Russian Mir station, and earlier as a backup base module for Mir. Therefore, Zwiezda is very similar to the main module of the Mir station (DOS-7). Construction began in the mid-80s. When Russia joined the ISS International Space Station construction project, the Mir-2 station was abandoned, and the built module named Zwiezda became the third of the main ISS modules.
In Zwiezda, there are two crew cabins (with one window in each), a refrigerator, a freezer, a toilet, communication and navigation equipment, gym exercise equipment, an orbit correction system with a fuel supply, and a system for obtaining oxygen from wastewater. It also has three docking nodes: the axial rear one is used for connections with Soyuz-TM and Soyuz-TMA ships and Progress-M transporters, as well as M1 and ATV; the axial front one is for a permanent connection with the Zaria module; two nodes located at the top and bottom in the front part are intended for attaching further Russian ISS elements.
Zwiezda was launched into orbit using a Proton-K rocket on July 12, 2000, at 04:56:36 UTC. Its connection with the ISS took place two weeks later – on July 26 at 00:44:44 UTC.
Destiny – is the primary research laboratory for American research projects aboard the International Space Station. It was connected to the Unity module and activated within five days at the beginning of February 2001. This module is NASA’s first orbital research station since the last crewed occupancy of the Skylab space station in February 1974.
The aluminum module is 8.5 meters long and 4.3 meters wide. It is divided into three cylindrical sections and two cone-shaped end sections. These cones contain hatches through which astronauts enter and exit the module. Destiny is connected to the front wall of the Unity module.
Similar to the planned Japanese and European laboratories attached to the ISS, research payloads inside Destiny are arranged in International Standard Payload Racks (ISPR). Each rack weighs about 540 kg. Destiny was placed in orbit along with five racks containing life support systems that provide electricity, water cooling, air revitalization, and temperature and humidity control. Seven subsequent racks were sent to the Destiny module aboard the Leonardo Multi-Purpose Logistics Module as part of the STS-102 mission, and another ten were delivered in subsequent missions.
Four stations contain connections to the module’s subsystems – the channels contain cables and pipes that run to and from individual racks and through the laboratory. In total, Destiny can accommodate 23 racks – six on each side and the ceiling, and 5 on the floor.
Astronauts work inside the pressurized, airtight module. They conduct research there in various fields of science. Scientists from all over the world can use the research results to expand their knowledge in medicine, engineering, biotechnology, materials science, and Earth studies.
Boeing began construction of the 14.5-ton research laboratory in 1995 at the George C. Marshall Space Flight Center in Huntsville, Alabama. The Destiny module was delivered to the Kennedy Center in Florida in 1998. NASA began preparations for launch in August 2000. It was placed in orbit on February 7, 2001, aboard the space shuttle Atlantis as part of the STS-98 mission.
The interior of the laboratory consists mainly of racks and workstations. Equipment is stored in the form of modular racks. The racks are connected to the installation (e.g., electrical) using connectors located at the workstations.
Connectors in the collar, the space between the Unity and Destiny modules, connect pipes and cables between these modules. Additionally, extra grounding cables will be installed. One side of the grounding will be connected to the Active Common Berthing Mechanism of the Unity module, the other – to the passive mechanism (Passive Common Berthing Mechanism) of the Destiny module.
Other systems on Destiny include docking mechanisms (passive and active), hatches, and a laboratory window shutter. The active docking mechanism is located on the front port of the laboratory. It will be connected to the passive connector of the PMA 2 module when the PMA is attached to the front of Destiny. The active connector of the Destiny module cannot be used before the laboratory is activated. The passive connector is located on the rear port. The active connector on the front of the Unity module will be mated with the passive connector of the laboratory to connect Destiny with Unity.
Each of the two Destiny connectors contains a hatch. The rear hatch (to the Unity module) will be opened and will remain in that position unless a situation requiring laboratory isolation occurs. The forward hatch (to the Harmony module) is also constantly open.
Each hatch has a window. Hatches can be opened and closed from both sides. The hatch contains a pressure lock that prevents the hatch from opening if the pressure on one side is very low.
Destiny contains a window of a quality that allows for scientific observations of the Earth. This window has a shutter that protects it from potential micrometeorite impacts and orbital debris. The crew manually opens the shutter to use the window.
Destiny also contains a Minus Eighty Degree Laboratory Freezer for ISS – MELFI, transported to the station in the STS-121 mission. This freezer is used to store samples and substances aboard the ISS, as well as to transport them to and from the station in a temperature-controlled environment.
„Quest” Joint Airlock and High Pressure Gas Tanks (JAHPGT) – American component of the International Space Station. It was launched into orbit on July 12, 2001, aboard the shuttle Atlantis (STS-104 mission).
This module is a $164 million airlock, $5.5$ m long, with a diameter of $4$ m at its widest point, a mass of $6064$ kg, and a usable volume of $34$ m³, allowing astronauts to exit into outer space. It is made of aluminum and consists of two cylindrical cells connected to each other. The first, in the form of a ring, is a storage room for EMU pressurized suits; the second, in the form of a core, is the actual chamber that is depressurized before starting a spacewalk. This chamber has a hatch through which astronauts can exit and begin operations on the outer structure of the station. Thanks to a special interface, the airlock allows exiting into space in both American (EMU) and Russian (Orlan) suits. The airlock’s design provides for minimal air loss when opening its outer hatch. Four tanks (High Pressure Gas Tanks) are installed on the ring chamber, two of which contain oxygen and two nitrogen. Three of these tanks are installed in the lower part of the airlock, one in the upper. The diameter of each tank is exactly $90$ cm, capacity $42$ m³, mass $545.4$ kg. These tanks store gases that create an artificial atmosphere in the airlock chambers; furthermore, they are intended to support air circulation throughout the station. Additionally, the tanks in the spacesuit backpacks are filled with air created this way before each spacewalk. HPGTs are replenished with a new supply of oxygen and nitrogen always at the end of a shuttle mission. The pumping of air components occurs through a system of atmospheric lines connecting with the air control systems on the shuttle. These lines are located in each of the station’s modules, including the PMA (Pressurized Mating Adapter). Each of the tanks has a special shield against micrometeorites.
Quest was mounted to one of the horizontal nodes of the Unity module as part of assembly mission 7 A. An ESP2 pallet delivered by the shuttle Discovery during the STS-114 mission is attached to the airlock.
Harmony (Node 2) – one of three modules serving as connecting corridors between other laboratory modules of the International Space Station.
Node 2, built by the European Space Agency for NASA, constitutes a hub between three modules: the American Destiny, the European Columbus, and the Japanese Kibō.
It has the shape of a cylinder with six connection nodes. Compared to its twin Node 1 (Unity), it is slightly longer, while having the same diameter. Harmony has racks on board containing instruments responsible for processing electrical energy and transmitting it to the JEM „Kibō” and Columbus modules.
Harmony was placed in orbit in October 2007 as part of the STS-120 mission of the shuttle Discovery (assembly mission 10A). During the mission, through one of its horizontal nodes, Harmony was temporarily attached to the Unity module. On November 14, 2007, the module was moved and connected to the Destiny laboratory. In turn, PMA-2 (Pressurized Mating Adapter 2) was connected to the second main horizontal node. The Japanese JEM Kibō laboratory and the European Columbus laboratory are connected to the remaining two horizontal ports. A canceled CAM module was to be attached to the upper node; in 2015, a PMA-3 docking adapter was attached to it. The lower node is used as an entrance for MPLM containers (until 2011 due to the retirement of space shuttles), HTV Kounotori vehicles, and is also a docking site for Cygnus and Dragon spacecraft.
Based on an agreement between NASA and ESA, Node 2 was built by the Italian company Alenia Spazio (now Thales Alenia Space) at its facility in Turin.
Columbus – European scientific laboratory intended for the International Space Station (ISS). Initially, it was to constitute the main module of the independent Columbus orbital station planned by ESA.
The laboratory was originally part of the Columbus program conducted by ESA and aimed at placing an independent crewed station in orbit, allowing for scientific experiments in the field of microgravity. The program was implemented in the years 1986–1991. The program initially assumed the construction and launch of three elements – Man-Tended Free Flyer, the pressurized APM module, and the Polar Platform. The stations were to be serviced by Hermes shuttles. This program was canceled, while subsequent budget cuts meant that ultimately only the APM remained from the Columbus program. The module was renamed Columbus and included in the ISS construction program, of which it is the largest independent European element.
The laboratory was constructed in Bremen by the European Space Agency and EADS Space Transportation as the main contractor. The flight module, the micrometeorite protection system, the module responsible for temperature, and several other modules were built in Turin at the Alenia Spazio facility.
The Polish contribution to the construction of the laboratory consists of two miniature ARISS antennas designed by a team led by Dr. Paweł Kabacik from the Wrocław University of Science and Technology.
Columbus (in the foreground) a few hours after docking with the ISS. Atlantis, the Harmony module (Node 2), and the Destiny laboratory (on the right) are visible in the background. Astronaut Rex Walheim during a spacewalk (EVA) at Columbus.
Columbus was under construction for 10 years. On May 27, 2006, it was transported from Bremen to the KSC. On February 7, 2008, the module was launched into orbit as part of the STS-122 mission of the Space Shuttle Atlantis. On February 11, 2008, Columbus was attached to the starboard docking port of the Harmony module.
Ongoing scientific experiments cover such fields of research as plant biology, exobiology, heliophysics, human physiology, and fluid physics. Later, the Japanese scientific module Kibō was also attached to the ISS. It is located on the opposite side of Node 2 relative to the European module.
Kibō (JEM) – a Japanese laboratory, a component of the International Space Station (ISS), the first section of which was installed during the STS-123 mission in March 2008. Designed by the Japan Aerospace Exploration Agency (JAXA), Kibō’s primary purpose is to conduct scientific experiments in a vacuum.
JEM has workstations for two people to work simultaneously; however, up to four ISS crew members can be in the laboratory at the same time.
System operations and experiments conducted in Kibō are controlled from the Mission Control Room at the Space Station Operations Facility located at the Tsukuba Space Center (Ibaraki Prefecture, Japan).
On May 30, 2003, the PM module was transported from Japan to the United States, to the John F. Kennedy Space Center. NASA launched the entire JEM complex into orbit in three flights:
Kibō Experiment Logistics Module Pressurized Section (ELM-PS) – temporarily attached to the bottom docking port of the Harmony module on March 14, 2008, during the STS-123 mission; after the installation of the PM on June 6, 2008, it was moved to its final location at the top of the PM module.
Pressurized Module (PM), Remote Manipulator System (JEMRMS) – attached to the port (left) docking port of Harmony, and then connected to the JEM ELM-PS between June 3–8, 2008 (STS-124 mission).
JEM consists of four parts:
PM (Pressurized Module) – the main component of JEM; a hermetically sealed module – „under pressure”. It is cylindrical in shape (11.2 m high and 4.4 m in diameter), with two nodes – one horizontal, through which it was mounted to Node 2 (during flight 1 J/A), and a second vertical node where the ELM-PS was installed. It also features an airlock, which allows for the easy exchange of certain experimental material containers on the EF research platform. The JEMRMS crane was also mounted to the PM. The Kibō module is equipped with 23 racks, 13 of which contain experiment monitoring equipment, while the remaining 10 are intended for experiment objects (5 of the latter will be used by NASA, and the remaining 5 by JAXA). Helium, carbon dioxide, and argon tanks are installed inside the module as experiment components.
EF (Exposed Facility), an uncovered installation also simply called the „terrace” – is a research platform attached to the outside of the PM. Payloads with experimental materials placed on it are exposed to the open space environment (high vacuum, strong cosmic radiation, etc.).
From inside the station, astronauts can exchange the experiments being conducted using the JEMRMS manipulator.
ELM (Experiment Logistics Module) – supply and storage modules. One section is hermetically sealed (ELM-PS, Pressurized Section) and is connected to the PM module. The second, uncovered section (ELM-ES, Exposed Section) is attached to the EF platform.
Both parts were designed to simultaneously serve as containers for transporting supplies to/from Earth (on board space shuttles), and as storage for experimental materials, system equipment, tools, etc. (when the ELMs are attached to the ISS). JEMRMS (Remote Manipulator System) – a robotic manipulator with equipment that is attached to a port on the PM module. It is used to move equipment to and from the EF platform and the ELM-ES module, as well as to unload the unpressurized segment of HTV Kounotori ships.
The JEMRMS system consists of:
Main Arm – specialized for moving heavy payloads; it is equipped with a TV camera that allows astronauts to monitor operations from inside the PM module.
Small Fine Arm – can be attached to the end of the main arm; intended for performing precision operations and moving small payloads.
RMS console – the crane control station located inside the Pressurized Module. It is equipped, among other things, with a monitor and a control panel for the camera mounted on the main arm, a set of joysticks controlling the rotational and translational movement of the manipulator, and a laptop.
Poisk – a Russian airlock installed on the International Space Station. Structurally, Poisk is very similar to the Pirs airlock. It was attached to the upper node of the Zvezda module.
It was originally intended to be attached to one of the side ports of the Universal Docking Module. Construction of the airlock began in 2002; however, it was interrupted after the suspension and subsequent cancellation of the Universal Docking Module. The decision to continue work was not made until October 2007. Construction resumed in June 2008 and was completed in early 2009.
The module was launched on November 10, 2009, at 14:22 UTC via a Soyuz-U rocket. Similar to the Pirs module, Poisk reached the station using a modified instrumentation and propulsion segment of a Progress spacecraft. Docking with the ISS took place on November 12, 2009, at 15:41 UTC. On December 8, 2009, at 00:16 UTC, the instrumentation and propulsion segment was detached from MRM-2 and subsequently burned up in the Earth’s atmosphere.
Tranquility (Node 3)
The last of the planned connecting modules for the International Space Station (ISS), which, like its twins Node 1 (Unity) and Node 2 (Harmony), serves as a corridor between various sections of the station.
The module was built for NASA by Thales Alenia Space in Turin under a contract with the European Space Agency. Construction of Node 3 began in 2006, with completion originally planned for May 2008. The module was delivered to the John F. Kennedy Space Center in May 2009 aboard an Airbus Beluga aircraft. It was attached to the ISS in February 2010 along with the Cupola module via the shuttle Endeavour during the STS-130 mission.
Initial plans depicted Node 3 as a nearly identical module (compared to Node 1 and Node 2); however, it was later decided that Node 3 would partially replace the canceled Transhab. Under the new design, the module would house many devices originally intended for Transhab, including:
A refrigerator-freezer
A treadmill
A kitchen
A storage area
Water tanks
A toilet (Waste and Hygiene Compartment)
Special compartments for clothing, medicine, and food
Additionally, the module contains the station’s atmospheric revitalization system, which removes contaminants from the air and monitors/controls atmospheric content, as well as a modern life support system (waste water recovery, oxygen production).
The Cupola observation module was attached to the module (inside which the control station for the Canadarm2 manipulator—the Robotic Work Station—is located). A canceled habitation module was also intended to be attached to Node 3.
Cupola
An observation module of the International Space Station, designed and built by Alenia Spazio (now Thales Alenia Space) on behalf of the European Space Agency. Alenia Spazio was the prime contractor and coordinated the work of six other firms: APCO (Switzerland), CASA (Spain), EADS (Germany), SAAB Ericsson and Lindholmen Development (Sweden), and Verhaert (Belgium).
The interior of the Cupola was specifically designed to house one of two identical RWS (Robotic Work Station) workstations, which control the operation of the Canadarm2 robotic arm.
The Cupola allows for a direct, panoramic view from inside the station of: operations performed by the robotic manipulator, spacewalks by astronauts, space shuttle docking maneuvers, and technical inspections of external equipment. It also serves as an excellent observation point for Earth and other celestial bodies.
The Cupola is approximately 2 meters in diameter and 1.5 meters in height. It features six trapezoidal side windows and one circular top window with a diameter of 80 cm (all made of armored glass). Each window is further equipped with a shutter to protect against impacts from micrometeoroids and space debris.
Rassvet is a Russian module of the International Space Station. It is primarily used for cargo storage and as a docking module for the station. It was delivered to the ISS during the STS-132 mission of the space shuttle Atlantis in May 2010.
Rassvet, adapted for launch by an American shuttle under barter agreements, was completed in 2009 and delivered to Florida on December 17 for final testing and flight preparation. Packed with supplies, the module was launched along with the rest of the cargo and the mission crew from Launch Complex 39 at the Kennedy Center on May 14, 2010. According to the plan, on the fifth day of the mission (May 18, 2010), Rassvet was connected to the station by the STS-132 crew. It was guided out of the shuttle’s cargo bay using the Atlantis shuttle arm and then docked to the bottom (nadir, facing Earth) node of the Zarya module using the Canadarm2 manipulator. The hatch connecting the new module to the station was opened for the first time on May 20. Specifically protected cosmonauts entered Rassvet to remove any noticed metal shavings.
In terms of construction, the module is strikingly similar to the shuttle docking module that operated from 1995 to 2001 on the Mir station. Its early design, under the name SGM (Stykowoczno-Gruzowoj Moduł) / DCM (Docking and Cargo Module), was ready in 2006. Rassvet is equipped with two docking nodes: one is attached to Zarya, while the second (designated as SO-3/DC-3) is used for docking Soyuz and Progress vehicles, which had become difficult after the Tranquility module was attached to the station.
The applied nodes (SSWP G4000 type) allow for the transfer of fuel from an attached Progress vehicle to the Zvezda module. Furthermore, the module has a small airlock and a radiator for the planned Russian Multipurpose Laboratory Module Nauka, as well as an extension for the European Robotic Arm, which was intended to be launched in 2015.
Rassvet was built in two years by the „Energia” company, named after S.P. Korolev, using a pressurized equipment compartment from an unrealized element of the Russian segment of the ISS—the Science Power Platform (NEP).
Small Research Module 1 contains five multipurpose workstations for conducting research in the pressurized section, four of which are equipped with scientific instrumentation aids: a glovebox, multipurpose biotechnological thermostats (low-temperature and high-temperature), and a vibration isolation platform. The fifth workstation is to be equipped with adapters allowing for the connection of specialized scientific equipment (special sliding modular shelves). Several experiments were planned before launch. Inside, there is also to be one workstation for conducting experiments on the external surface of the module.
Multi-Purpose Logistics Module (MPLM) – a large pressurized container used in American space shuttle supply missions to transport cargo to and from the International Space Station (ISS). The module was carried into orbit in the shuttle’s cargo bay and attached to one of the free docking nodes of the Unity module for the duration of the mission; it was then unloaded of tools and equipment needed on the station, and filled with used station components and waste. At the end of the mission, the module returned to the shuttle’s cargo bay.
Three twin logistics modules were created and named: Leonardo, Raffaello, and Donatello.
Compared to Progress spacecraft, the MPLMs offer a much larger storage volume, allowing for the transport of larger items included in the supplies. Their equipment includes, among other things, 16 racks, including special freezers for transporting experiment samples. The MPLM can carry approximately 9 tons of payload. None of the modules have their own power system; however, each is pressurized, maintaining an artificial atmosphere during the flight into orbit and during the return to Earth (the MPLM can remain in orbit for a maximum of 16 days while attached to the ISS).
After the STS-131 mission, the MPLM Leonardo was converted into the Permanent Multi-Purpose Module (PMM), which flew with the STS-133 mission (the final flight of the shuttle Discovery). Among the changes introduced were reinforced module shields to protect against micrometeoroid impacts. The conversion allowed for a permanent connection to the ISS for an unlimited time—thus, the PMM serves as an additional storage room on the ISS.
The MPLMs were built for NASA by the Italian Space Agency (ASI) and are American property. In settlement, ASI received access to a portion of the U.S. research time on the ISS. The very idea of the module’s creation was born during the design phase of the never-built Space Station Freedom. Originally, the project was to be carried out by Boeing, but in 1992, ASI announced its readiness to undertake this type of project. Preliminary plans were changed, and in 1993, a project for this module in a version twice as large was created and ultimately accepted. Construction of Leonardo began in April 1996 at the Alenia Spazio factory in Turin. It was delivered to the KSC in August 1998 by an Airbus Beluga aircraft. Raffaello was delivered in August 1999, and Donatello in February 2001.
The Donatello module was never used for a flight, and some of its parts were used for the conversion of the Leonardo module into the PMM.
The MPLM itself has the form of a cylindrical, pressurized „large can,” measuring 6.4 m in length and 4.6 m in diameter. Its volume is 31 $m^3$. When empty, it weighs 4082 kg, but it can deliver 9.1 tons of goods.
Bigelow Expandable Activity Module (BEAM) – an inflatable, test habitation module that has been an element of the International Space Station since 2016, developed by the company Bigelow Aerospace under a contract with NASA. It serves as a test module to be attached to the station in the years 2016–2018 to check the suitability of this type of construction in manned astronautics. The company plans to build a second identical module, which will serve as an airlock for its planned commercial station.
In early 2010, NASA returned to the idea of using inflatable habitats similar to the Transhab design. At that time, the use of designs from the Bigelow company, which had taken over this technology, was considered. Plans included, among others, a toroidal-shaped module called the Bigelow Expandable Activity Module. This type of module was intended to serve as a test centrifuge construction for the Nautilus-X project. In January 2011, Bigelow anticipated construction and flight preparation within 24 months of signing a contract.
On December 20, 2012, NASA awarded Bigelow a $17.8 million contract to enable the construction of the module as part of the agency’s Advanced Exploration Systems program.
NASA’s plans were announced in 2013, with a planned launch date for the new module in 2015. The construction deadline was met. The launch of the module, planned for September 2015, was delayed due to the explosion of a Falcon 9 rocket shortly after liftoff during a resupply mission to the International Space Station on June 28, 2015. Ultimately, the BEAM module was launched into space on April 8, 2016, using a Falcon 9 rocket in its new Full Thrust version, as part of the CRS-8 resupply mission.
Bigelow Aerospace plans to build a second BEAM module, which will serve as an airlock for Bigelow’s planned commercial station. The module’s structure will allow it to accommodate up to three people at once—one more than the airlocks on the ISS allow.
The version of the module contracted by NASA is cylindrical in shape and is smaller than the originally planned torus. As part of the contract signed in May 2013, the Sierra Nevada Corporation manufactured the $2 million Common Berthing Mechanism, which is used to moor the module to the ISS.
Multipurpose Laboratory Module „Nauka”
Multipurpose Laboratory Module „Nauka” – a module funded by the Russian agency Roscosmos, which was launched into Earth orbit and attached to the International Space Station in 2021.
The hull of the „Nauka” module was built in the 1990s, based on the design of the TKS transport spacecraft from the late 1960s. The module, then named FGB-2 (Functional Cargo Block-2), was built by the Khrunichev State Research and Production Space Center as a backup unit in case the FGB „Zarya” module was lost. „Zarya” was placed in orbit in 1998, becoming the beginning of the International Space Station, while the 80% complete FGB-2 module remained on Earth. The Russian side proposed using it as a replacement for the American „Destiny” module, whose launch was delayed, but in 2001 it too reached orbit. It was also proposed to convert FGB-2 into a universal docking module, but that idea was abandoned.
In 2004, it was decided that the backup module would be converted into a laboratory for the Russian Orbital Segment of the International Space Station and sent in 2007. This required a thorough reconstruction. Work was delayed; the launch date was postponed to 2009, and then to 2012. In December 2012, the module was transferred from the Khrunichev Center to RKK Energia for testing.
In 2013, a series of defects were detected in the module. A leak was discovered in one of the propulsion system valves, caused by metal shavings in the fuel lines. An official review indicated that the shavings resulted from failure to follow work procedures (unofficial reports suggested workers were convinced the module’s components were intended for scrapping). At the end of the year, the module returned to the Khrunichev Center; the launch date was moved to 2016.
In 2017, the same type of metal shavings were found in the module’s fuel tanks. Attempts to clean them failed, and eventually, all original lines and valves were dismantled. In 2020, May 2021 was indicated as the launch date. After testing was completed, the module was finally ready for launch in July 2021.
On September 3, 2021, cosmonauts Oleg Novitsky and Pyotr Dubrov, dressed in Orlan spacesuits, performed a spacewalk to install cabling on Nauka. On September 9, 2021, a second spacewalk took place to connect space equipment to the MLM. On January 19, 2022, cosmonauts Anton Shkaplerov and Pyotr Dubrov performed a third spacewalk to install connections between Nauka and Prichal.
On November 21, 2023, Nauka’s airlock was integrated with the Russian segment of the International Space Station, marking the 25th anniversary of launching Zarya to the ISS.
The module was ultimately launched into Earth orbit on July 21, 2021, at 16:58 CEST. A Proton-M rocket carried it from the Baikonur Cosmodrome in Kazakhstan. The module separated from the rocket and deployed its communication antennas and solar panels.
Shortly after launch, problems appeared with the „Nauka” module. It was not possible to start its main engines, but the ground crew managed to raise the orbit using backup thrusters. There was also an issue with the Kurs docking system, which was meant to be used for safe docking with the station.
„Nauka” was intended to be attached to the nadir docking port on the „Zvezda” module adapter. Since 2001, the „Pirs” airlock had been attached to this port. It was detached and burned up in the Earth’s atmosphere along with a Progress cargo ship. Due to the problems with „Nauka,” the detachment of the airlock was delayed by several days compared to the plan. „Nauka” docked with the station on July 29, 2021, at 13:29 UTC (15:29 Polish time).
Problems did not end after docking. A few hours after connecting to the ISS, the module unexpectedly started its engines as if it were trying to move away from the station to which it was already attached. The cause was an error in the module’s software. As a result, control over the orientation of the International Space Station was lost, and it rotated by approximately $540^\circ$. To stop the rotation, the engines of the „Zvezda” module and the „Progress” ship were started. Nauka’s engines shut off after 15 minutes, and the station returned to its proper orientation.
„Nauka” is the largest module in the Russian orbital segment of the ISS. It serves primarily as a laboratory and also has an airlock allowing for spacewalks. The module contains sanitary facilities, an air regeneration system, and can sleep one cosmonaut.
For laboratory research, the Nauka module provides over 30 universal workstations (URM). The high degree of automation of MLM-U Nauka reduces the number of costly spacewalks—many operations outside the cabin can be performed without leaving the station. Outside the module, there are 13 external universal workstations (URM-N) and the ERA manipulator for automated handling or maintenance. In Nauka’s pressurized compartment, 20 internal universal workstations (URM-W) are organized. URM-W workstations include four stations with sliding shelves, including a glovebox, a frame with an automatically rotating anti-vibration platform, and a station with a 426 mm diameter porthole for visual, instrumental, and other observations.
Along with „Nauka,” the European Robotic Arm (ERA) arrived at the station, which serves the Russian part of the International Space Station, operating on the exterior. In November 2021, a new connecting module, „Prichal,” was attached to the nadir port of the MLM-U.
Pirs – a Russian airlock that was part of the International Space Station (ISS) from 2001–2021. It allowed for spacewalks without the need for prior depressurization of the „Zarya” and „Zvezda” module forward sections. It was built by RKK Energia.
Pirs was launched into orbit as part of mission 4R via a Soyuz-U rocket. The launch took place on September 14, 2001, at 23:34:55 UTC from the Baikonur Cosmodrome in Kazakhstan. On September 17 at 01:05 UTC, thanks to a propulsion system borrowed from Progress-M spacecraft designs (the complex, which included Pirs during its flight to the station, was designated Progress-M-S01), it automatically docked to the bottom vertical node of the Zvezda module. After this operation, the propulsion section that delivered the airlock to the Zvezda port was jettisoned as it was no longer needed and burned up in the atmosphere.
In addition to its function as an airlock, Pirs also served as a port for Soyuz manned spacecraft and Progress cargo ships. Fuel delivered to the station by Russian cargo ships was also pumped through the module.
Compared to other Russian modules, Pirs was small. The module’s launch mass was 4,350 kg, while its mass in orbit was 3,580 kg. The module’s length was 4.91 m, and its maximum diameter was 2.55 m. Its internal volume was approximately 13 $m^3$. Pirs featured two external hatches with a diameter of 1 meter; this size was entirely sufficient for comfortably exiting the station structure in Russian Orlan spacesuits. The hatches were equipped with windows with an internal diameter of 228 mm. Handrails were placed around the hatches, both outside and inside the module, to help cosmonauts pass through the opening.
Pirs was equipped with its own ventilation system as well as a room for spacesuits. Meanwhile, the basic equipment installed on the outside of the airlock consisted of two Strela cranes. In 2012, both cranes were detached from Pirs and moved to the Poisk airlock (Strela-1) and the Zarya module (Strela-2). This operation was carried out because Pirs was intended to make way for the new MLM Nauka module in 2013. After many construction delays, Nauka reached the ISS in 2021. Due to problems with the new module, the undocking of Pirs was postponed. Pirs was finally detached on July 26, 2021, at 10:55 UTC and deorbited four hours later at 14:51 UTC.
Supply Ships
In addition to crew exchanges, it is essential to supply the station with food, spare parts, materials, and research equipment. Due to the prospect of retiring the American space shuttles in 2011, it became necessary by the end of the first decade of the 21st century to find other ways to resupply the station. Russian Progress transport ships, due to their low cargo capacity, were unable to fully fulfill these tasks. Consequently, the station partners—the European ESA and the Japanese JAXA—undertook the construction of new, larger transport ships launched into orbit by their own rockets, which were named ATV and HTV (Kounotori), respectively.
After completing five successful resupply flights between 2008 and 2015, the ATV ships were retired from service. Meanwhile, the HTV ships, which also performed five flights between 2009 and 2015, were expected to remain in operation until 2019.
Furthermore, as part of the Commercial Resupply Services program, commercial spacecraft built by private astronautics companies reach the ISS: Cygnus from Orbital Sciences Corporation and Dragon produced by SpaceX. To date, there have been more than 22 launches of these spacecraft, of which over 20 have successfully delivered supplies to the station under the Commercial Resupply Services program.
