What Happens When Something Breaks on the International Space Station

Key Takeaways

• ISS repairs begin with fault detection, isolation, safe configuration, and ground support.
• Astronauts, robots, spare parts, cargo vehicles, and Mission Control form the repair chain.
• Age-related maintenance shapes ISS operations as NASA prepares for post-ISS platforms.

The First Minutes After a Failure on the International Space Station

The International Space Station travels about 250 miles above Earth at roughly 17,500 miles per hour, yet many of its repair decisions begin in a familiar way: an alarm sounds, a sensor reading changes, a component stops responding, or a crew member notices something unusual. The difference is that the International Space Station is a sealed, crewed spacecraft assembled over decades, supplied by launch vehicles, and supported by ground controllers in multiple countries. A broken part is never treated as an isolated inconvenience. It is assessed as part of a larger machine that must keep people alive, preserve research, maintain power, reject heat, communicate with Earth, avoid debris, and stay controllable in orbit.

When something breaks on the International Space Station, the first question is not whether the equipment can be repaired. The first question is whether the crew and spacecraft remain safe. Mission Control teams assess the fault, compare sensor data, review procedures, and decide whether the crew should keep working, stop an activity, close a hatch, power down equipment, or move to another area of the station. The crew trains for routine maintenance, emergency response, fire, depressurization, and atmosphere problems before launch. That training matters because an orbiting laboratory cannot wait for a local technician, a hardware store, or a next-day parts delivery.

A failure may be small, such as a filter that needs replacement, a laptop that loses function, or a science freezer that reports an abnormal temperature. Another failure may affect a system that supports the entire station, such as power distribution, thermal control, air revitalization, oxygen generation, water recovery, communications, docking hardware, or external equipment mounted on the truss. The station’s scale adds to the challenge. NASA’s space station facts and figures describe a structure 356 feet, or 109 meters, from end to end, with miles of wiring and many interconnected systems. A repair team must know which system has failed, which systems depend on it, and what secondary effects might follow.

The crew does not improvise major repairs without ground support. The International Space Station operates through a network of mission control centers, including NASA’s Mission Control Center in Houston, Russia’s mission control center near Moscow, and partner control teams in Europe, Japan, and Canada. Those teams monitor telemetry, maintain system histories, develop procedures, and guide astronauts through repair steps. Astronauts may be highly trained pilots, engineers, scientists, physicians, or mission specialists, but they also serve as the hands of a much larger ground organization.

Fault response usually follows a pattern. The crew and ground teams identify the problem, confirm that the reading is real, protect the crew, place the affected system in a safe condition, isolate the failed component, plan repair steps, execute the repair, test the system, and return hardware to service. That pattern sounds orderly because it must be. In space, a rushed repair can create another fault, contaminate the cabin, damage a connector, release fluid, or consume limited crew time that another system may need.

Small repairs may fit into a normal workday. Larger failures can reorder the entire station schedule. Research activities may pause, visiting vehicle operations may shift, and spacewalk planning may begin. The result is a repair culture built around patience, redundancy, checklists, and verification. The station can survive many failures because engineers designed it with backup systems, spares, replaceable units, cargo delivery options, robotic support, and escape vehicles. The repair process still demands discipline because every action occurs inside a machine that is also a home, a laboratory, and a spacecraft.

How Mission Control Diagnoses a Broken System

A broken system on the International Space Station usually announces itself through data before a crew member sees it directly. Sensors measure pressure, temperature, voltage, current, pump status, fan performance, carbon dioxide levels, oxygen levels, water quality, valve positions, computer status, and many other conditions. Ground controllers watch those measurements against expected limits. When a value drifts outside its normal range, specialists begin asking whether the fault comes from the hardware, the sensor, the software, the power supply, the data path, or an operational condition that the system did not expect.

Diagnosis often begins with fault isolation. A single alarm may point toward many possible causes. A pump may stop because the pump failed, because power stopped reaching it, because a controller shut it down, because a sensor produced a false signal, or because another system upstream or downstream changed state. Ground teams compare current data with previous trends, maintenance records, known failure modes, and recent crew activities. They also use procedures that tell the crew which switches to check, which status lights to inspect, which cables to reseat, and which modules or racks to access.

The Canadian Space Agency describes two broad categories of maintenance on the station: preventive maintenance and corrective maintenance. Preventive maintenance includes planned inspections, cleaning, replacement, and checks that reduce the chance of failure. Corrective maintenance responds to broken or non-functioning equipment. Both categories depend on crew training, ground analysis, spares, documentation, and realistic scheduling. A filter replacement may be routine, but a fault in a rack, pump, valve, robotic joint, or cooling loop can require many hours of planning.

The station’s maintenance culture favors replaceable units. Many systems use modular equipment that astronauts can remove and replace rather than repair down to the smallest internal component. This approach reduces time spent troubleshooting at a workbench in orbit. It also allows ground engineers to inspect the failed unit after return to Earth if the cargo system supports downmass. Replacement is not always simple. A unit may sit behind other equipment, attach with tight connectors, require special tools, contain fluid lines, or need careful software reconfiguration after installation.

Some faults affect the station’s schedule rather than immediate safety. A science payload may need repair to protect an experiment. A freezer fault can threaten biological samples. A communications issue can complicate commanding. A robot problem can postpone external work. Other faults demand faster action because they affect atmosphere, fire detection, thermal control, power, or crew escape readiness. Mission Control classifies the fault by risk, consequence, available redundancy, and repair timing.

The table below shows common categories of station breakage and the usual response logic behind them.

Diagnosis does not end when a repair appears successful. After a replacement or reconfiguration, ground teams watch data to confirm that the system operates within limits. The crew may run functional checks, inspect for leaks, photograph hardware, or report unusual sounds and odors. In orbit, a repair has two tests: the immediate test that the equipment works, and the longer test that it keeps working under vibration, temperature cycling, microgravity, and crew use.

Life-Support Problems Receive the Fastest Attention

Life-support systems receive special attention because the International Space Station must provide breathable air, safe water, pressure control, ventilation, fire detection, waste handling, and contamination control. NASA’s Environmental Control and Life Support Systems page describes three main parts of the U.S. life-support architecture: the Water Recovery System, the Air Revitalization System, and the Oxygen Generation System. Those names sound technical, but their purpose is direct. They help turn the station from a metal structure into a livable place.

A life-support problem does not automatically mean the crew is in immediate danger. The station carries backups, stores, procedures, and partner systems. Oxygen can come from more than one source. Carbon dioxide removal can shift between equipment. Water can be stored, delivered, recovered, and rationed if needed. Crew members can close hatches to isolate a module if pressure data suggests a leak. Escape vehicles remain docked so the crew has a way home if the station cannot support safe habitation. The station’s repair strategy begins with keeping the crew safe and buying time for a careful fix.

The Water Recovery System provides a strong example of why maintenance matters. NASA reported in 2023 that the station’s Environmental Control and Life Support System had reached a 98% water recovery goal. That achievement matters for station operations and for future missions beyond low Earth orbit because every liter of water recovered is water that does not need to launch from Earth. A broken processor, clogged line, degraded filter, or contaminated sample can affect both daily life and research operations. Repairing water equipment protects crew health and preserves the station’s value as a testbed for longer missions.

Air systems are just as demanding. Oxygen generation depends on hardware that splits water into oxygen and hydrogen. Carbon dioxide removal depends on equipment that scrubs exhaled carbon dioxide from cabin air. Ventilation fans keep air moving because warm air, moisture, and exhaled carbon dioxide do not rise and mix the same way in microgravity as they do in a room on Earth. If a fan fails, the concern is not just comfort. Poor airflow can create local pockets of stale air, affect sensors, and reduce cabin habitability.

Fire is another life-support concern. A fire inside a spacecraft is different from a fire in a building because smoke, combustion products, airflow, and evacuation options behave differently. Crew members train to respond to fire alarms, isolate power, locate the problem, use breathing protection, and move to safe areas. Ground teams help interpret sensor readings and decide when a module can be reentered. A false alarm still consumes time because the crew and controllers must treat it seriously until data shows otherwise.

Leaks also show why repair decisions can become operational decisions. The Russian Zvezda service module has experienced air-leak concerns that drew attention from NASA and Roscosmos, and mission managers have balanced inspection, sealing work, pressure monitoring, and crew safety. A small leak may remain manageable if pressure stays within safe limits and the affected area can be isolated. A growing leak would change operations because atmosphere is a consumable resource and pressure stability is basic to crew survival.

Life-support repairs require clean work, careful labeling, and strict procedures. A connector installed incorrectly can prevent a rack from operating. A filter placed in the wrong orientation can reduce performance. A fluid leak can create contamination. A software step skipped after hardware replacement can keep a healthy unit offline. The crew may be doing work that a technician on Earth would perform in a specialized facility, but they do it in a crowded module with limited tools, limited time, and many other mission demands.

Repairs Use Astronauts, Robotics, Spare Parts, and Cargo

Repairing the International Space Station depends on a supply chain that begins on Earth long before any part breaks. Engineers identify likely failure points, certify spare hardware, package equipment for launch, store tools in orbit, maintain procedures, and track the location of parts inside and outside the station. Cargo missions deliver experiment hardware, food, clothing, water, gases, maintenance equipment, and spare parts. NASA’s visiting vehicles page describes the role of cargo spacecraft in delivering supplies and hardware to the station. A working repair system depends on those deliveries.

The station stores many spare parts inside pressurized modules, where astronauts can access them in shirtsleeves. Other parts sit outside the station on storage platforms because they are large, designed for external systems, or needed near the truss. NASA’s station assembly material describes External Stowage Platforms that can hold spare parts outside the station, with heaters for equipment that needs thermal protection. External spares reduce the need to launch large replacement units after a failure, but using them may require robotics or a spacewalk.

Robotics reduces the number of tasks that require astronauts to leave the station. The Mobile Servicing System includes Canadarm2, the Mobile Base System, and Dextre. The Canadian Space Agency describes Dextre as a robot that maintains the station by handling delicate external tasks. Dextre can replace selected external units, move equipment, support experiments, and reduce spacewalk demands. This is a major safety advantage because spacewalks expose astronauts to vacuum, radiation, suit risk, debris risk, and demanding physical work.

Astronauts still handle many repairs directly. Inside the station, they replace filters, clean vents, swap electronics boxes, inspect seals, patch materials, troubleshoot laptops, collect samples, repair exercise equipment, service science hardware, and install replacement components in racks. They also take photos and video for ground specialists, label removed hardware, and package failed units for return or disposal. Repair work can be physically awkward because nothing has weight, but every object still has mass and momentum. A large component can drift, rotate, bump into equipment, or pull on cables if it is not restrained.

Cargo vehicles determine what repair options exist. SpaceX Dragon can bring cargo to the station and return selected hardware to Earth. Northrop Grumman Cygnus, Roscosmos Progress, and other cargo systems have supported station logistics in different ways. Some vehicles dispose of trash through destructive reentry. Others support return cargo. The ability to return failed hardware helps engineers understand what went wrong, improve future parts, and validate repair decisions. The ability to dispose of old hardware keeps the station from filling with unusable equipment.

The table below compares the main repair paths used when station hardware fails.

Repair work also depends on documentation. Procedures are written, tested, revised, and sometimes developed under time pressure after an unexpected fault. A repair may require the crew to read steps from a laptop or tablet, speak with ground specialists, and verify each step before moving forward. When a repair involves international partner hardware, the relevant partner team supplies expertise. Station maintenance is a multinational activity because the station itself is multinational.

When a Fix Requires a Spacewalk

External failures are among the most demanding station repairs because the crew may need to conduct an extravehicular activity, commonly called a spacewalk. A spacewalk is never the first choice if ground commanding, robotics, or internal repair can solve the problem. It requires suit preparation, tool configuration, airlock operations, crew timeline planning, ground simulation, safety review, and coordination with station attitude control, communications, power, and robotics. The spacewalkers must perform precise mechanical work in a pressurized suit that limits movement and touch.

Thermal-control repairs show why spacewalks remain necessary. The station uses external radiators and ammonia loops to remove heat from equipment. If a major external cooling component fails, the station may need to shut down selected equipment, shift loads, or operate with reduced redundancy until repair work occurs. NASA reported in 2013 that astronauts Rick Mastracchio and Mike Hopkins removed and replaced a faulty coolant pump module associated with one of the station’s external cooling loops. NASA later reported completion of the ammonia pump module installation after a second spacewalk. That repair showed the station’s dependence on both replaceable external units and crew capability outside the vehicle.

Spacewalk planning includes tool selection, route planning, tether management, fatigue management, and emergency return paths. A task that looks simple on Earth can take far longer in orbit because the astronaut must translate along handrails, manage body position, control floating tools, avoid sharp edges, and keep track of suit consumables. External work may occur near radiators, solar arrays, cables, antennas, payloads, and robotic equipment. Ground controllers track the timeline and tell spacewalkers when to adjust priorities.

Spacesuits themselves are repair systems, but they can also become the source of a fault. NASA’s review of the 2013 EVA 23 incident describes how European Space Agency astronaut Luca Parmitano reported water inside his helmet, prompting Mission Control to terminate the spacewalk and return the crew to the airlock. The incident led to investigation, corrective actions, and renewed attention to suit water intrusion. It remains one of the clearest examples of why spacewalk rules favor caution. A failure outside the station can quickly become a crew-safety matter inside the suit.

Not every spacewalk is an emergency repair. Many are planned upgrades, inspections, or maintenance tasks. The distinction matters because a planned replacement can still be response work if engineers know a component has aged, degraded, or reached a planned service point. Replacing batteries, routing cables, installing payload support equipment, and preparing spare parts all reduce future repair risk. Preventive external work can keep a later failure from becoming urgent.

Robotics can work with spacewalkers during complex repairs. Canadarm2 can move an astronaut, position equipment, or support an external unit. Dextre can hold hardware, perform compatible replacement tasks, or support inspection. Ground-operated robotics can also prepare worksites before the crew exits the station. The best repair plan often uses both human dexterity and robotic reach.

After a spacewalk repair, the job continues inside Mission Control. Controllers verify power, thermal behavior, data response, mechanical status, and system stability. A new unit may need activation steps and monitoring before managers declare it fully operational. The crew may spend hours stowing tools, drying suits, repressurizing the airlock, cleaning up equipment, and documenting the work. A spacewalk is a visible repair event, but it is only one part of a longer maintenance chain.

What Breakdowns Reveal About an Aging Space Station

The first module of the International Space Station launched in 1998, and the first long-duration crew arrived in 2000. By the mid-2020s, the station had operated far beyond the early assembly era that produced many of its most recognizable images. Age does not make the station unsafe by default, but it changes the maintenance problem. Hardware experiences thermal cycling, vibration, docking loads, radiation exposure, micrometeoroid and orbital debris risk, seal aging, software updates, contamination, and simple wear from human use.

NASA’s transition plan FAQ states that NASA has committed to fully use and safely operate the station through 2030, with the lifetime of the primary structure affected by dynamic loading and orbital thermal cycling. Those forces are ordinary parts of station life. Visiting vehicles dock and depart. The station moves from sunlight into darkness roughly every orbit. External surfaces experience harsh temperature swings. Mechanical connections, pressure seals, structural elements, cables, radiators, and modules all sit inside that long-duration environment.

Breakdowns on an aging spacecraft are not always dramatic. A stubborn valve, degraded sensor, worn fan, contaminated filter, aging computer, or leaking seal can consume time and planning. Minor faults matter because the station is an integrated spacecraft. Equipment that works at reduced performance may still limit operations. A backup that is unavailable during repair may leave less margin if another fault occurs. A system that requires frequent maintenance may reduce time available for science.

The station’s age also affects logistics. Some hardware may no longer be manufactured in the same way. Suppliers change. Electronics become obsolete. Certification standards evolve. Materials age on shelves. A spare part launched years earlier may need storage monitoring and compatibility checks. Engineers must decide whether to fly a new spare, repair an old unit, reconfigure around the failed equipment, or accept reduced capability for a time. Those decisions involve risk, cost, launch capacity, crew time, and the remaining station lifetime.

Orbital debris adds another repair concern. NASA reported that on April 30, 2025, the station used Progress 91 thrusters for a debris avoidance maneuver to increase distance from a fragment of a Chinese Long March rocket launched in 2005. Debris avoidance is not a repair in the usual sense, but it prevents damage that could require repair or threaten crew safety. Small debris can travel at high relative speeds, and even a small object can damage external hardware.

Aging also increases the importance of operational judgment. Managers must decide whether a component should be repaired immediately, monitored, replaced during a planned spacewalk, or left until a cargo mission can deliver hardware. A young station in assembly mode had frequent shuttle visits and large payload delivery capability. The later station depends on a different cargo and crew transportation system. Repair strategy must match the vehicles, funding, crew schedule, and operational priorities available at the time.

The station’s planned end also affects repair choices. NASA selected SpaceX to develop the U.S. Deorbit Vehicle that will support controlled deorbit at the end of station operations. As the station nears that phase, managers still need to keep it safe and scientifically useful, but they also need to avoid turning every aging component into a full modernization program. Maintenance near end-of-life becomes a careful balance: preserve safety, preserve research value, protect crew time, and avoid unnecessary upgrades for systems that have limited remaining service.

How ISS Repair Lessons Shape Future Space Stations

Every broken component on the International Space Station teaches future spacecraft designers something practical. The station has shown that long-duration human spaceflight depends on repairability as much as launch success. Equipment must be reachable, removable, documented, testable, and replaceable. Spares must be stored where they can survive. Tools must work in microgravity. Procedures must support crews who may not have designed the hardware. Ground systems must collect enough data to diagnose failures from 250 miles below.

Future commercial stations in low Earth orbit will inherit these lessons. NASA’s commercial space stations effort is built around a planned transition from the ISS to commercially owned and operated platforms. Maintenance will be a business issue as well as an engineering issue. A commercial station that supports research, manufacturing, private astronauts, national astronauts, media activity, or technology testing will need high reliability because customers will pay for usable time in orbit. Lost crew time and lost payload time will carry financial consequences.

Designers can reduce future repair burdens by making systems modular from the start. A rack that slides out cleanly, a pump that connects with fewer fittings, a filter that can be changed without moving unrelated hardware, and a sensor that can be tested without disassembling a system all save time. The ISS has shown that crew time is one of the most limited resources in orbit. Even when a part is available, the repair may compete with science, exercise, medical checks, cargo unloading, docking preparation, and normal station upkeep.

Robotics will likely become more important. Dextre and Canadarm2 proved that robots can reduce direct human exposure during external maintenance. Future stations may design more equipment for robotic replacement from the beginning. Standardized grapple fixtures, compatible connectors, clear camera views, and modular external units can make robotic repair more practical. That does not remove astronauts from maintenance. It lets crew members focus on tasks where human judgment and dexterity matter most.

Life-support lessons will also carry forward. The ISS has provided long operating experience with water recovery, oxygen generation, carbon dioxide removal, microbial control, waste handling, and air monitoring. A future station can use those lessons to build systems that need less maintenance, provide better diagnostics, and tolerate faults without immediate crew intervention. The goal is not a station that never breaks. The realistic goal is a station that breaks in predictable, contained, repairable ways.

Cargo planning will remain central. A commercial station may need a different spare-parts model than the ISS because ownership, customer base, vehicle access, and mission tempo may differ. Operators may keep more spares in orbit for high-demand systems, use predictive maintenance to time deliveries, or design equipment around shorter replacement cycles. Insurance, service contracts, safety regulation, and customer agreements may all influence maintenance planning.

The repair culture developed on the ISS may be one of its most valuable legacies. The station has turned maintenance into a normal part of living in orbit. Astronauts fix equipment, clean filters, inspect hardware, swap parts, support spacewalks, operate robotics, and work with ground specialists as part of routine mission life. Future space stations will need the same mindset. A space station is not successful because nothing fails. It succeeds because failure is anticipated, contained, understood, and repaired before it grows into something larger.

Summary

A failure on the International Space Station starts a chain of decisions that blends engineering, operations, crew training, logistics, and risk management. The first task is always safety: protect the crew, protect the spacecraft, and understand the fault before repair work begins. From there, the response may involve software commands from the ground, a crew procedure inside a module, a robotic operation outside the station, a replacement part from storage, a cargo delivery from Earth, or a spacewalk.

The station’s maintenance system works because many layers support it. Mission Control diagnoses faults through telemetry. Astronauts carry out inspections and repairs. Partner agencies contribute hardware expertise. Cargo vehicles deliver replacements. Robotics reduces spacewalk exposure. Spacewalkers handle external repairs that no internal or robotic procedure can complete. Backup systems preserve margin when a component fails.

Age has made ISS maintenance more demanding, but it has also made the station more valuable as an operating example. The station has accumulated decades of experience with life support, thermal control, debris avoidance, external repair, logistics, robotics, and crew procedures. Every repaired pump, replaced filter, isolated leak, tested rack, and avoided debris object has added to the knowledge base for future stations.

The next generation of low Earth orbit platforms will not escape breakage. Pumps will still wear, sensors will still drift, filters will still clog, seals will still age, and humans will still need safe air, water, power, and thermal control. The ISS shows that the right question is not whether a spacecraft can avoid every failure. The right question is whether it can detect failures early, isolate them safely, repair them efficiently, and keep people working in orbit.

Appendix: Useful Books Available on Amazon

• Endurance: A Year in Space, A Lifetime of Discovery
• The International Space Station: Operating an Outpost in the New Frontier
• An Astronaut’s Guide to Life on Earth
• Packing for Mars
• Spaceman
• The Ordinary Spaceman
• Chasing Space

Appendix: Top Questions Answered in This Article

What happens first when something breaks on the International Space Station?

The first step is to protect the crew and place the affected system in a safe condition. Mission Control reviews telemetry, compares sensor data, checks procedures, and works with the crew to confirm what failed. Repair begins only after teams understand the immediate safety risk and the effect on station operations.

Can astronauts fix broken equipment without help from Earth?

Astronauts can perform many repairs, but major station maintenance usually involves ground support. Mission Control teams provide system expertise, step-by-step procedures, data review, and planning. The crew supplies inspection, handling, replacement, and judgment inside the station or during external work.

What kinds of equipment break on the station?

Failures can involve fans, filters, pumps, valves, sensors, computers, science payloads, power equipment, cooling systems, robotic components, life-support hardware, and external structures. Many issues are routine maintenance items. Some become high-priority events when they affect crew safety, station control, thermal balance, or power.

Does a broken life-support system put the crew in immediate danger?

A single life-support fault does not usually mean immediate danger because the station has backup systems and procedures. Oxygen generation, carbon dioxide removal, pressure control, ventilation, and water systems have redundancy or workarounds. The crew and ground teams still treat these faults with high urgency because habitability depends on them.

How do spare parts reach the International Space Station?

Cargo spacecraft deliver spare parts, food, equipment, research hardware, and consumables from Earth. Some spare parts are stored inside the station, and some large external spares are stored outside. Cargo planning is part of station maintenance because a missing spare can delay repair or limit operations.

Why does the station use robots for repairs?

Robots can reduce the need for spacewalks by handling compatible external equipment. Canadarm2 and Dextre support maintenance, equipment movement, inspections, and selected replacements. Robotic work helps protect crew members because spacewalks require complex preparation and expose astronauts to the space environment.

When does a repair require a spacewalk?

A repair may require a spacewalk when the failed hardware sits outside the pressurized station and cannot be fixed through ground commands or robotics alone. Spacewalks can replace cooling components, route cables, service external payloads, prepare spare parts, and inspect exterior systems. These activities require extensive planning and safety review.

Why do station repairs take so much planning?

Repairs take planning because the station is a connected spacecraft, not a stand-alone machine. A repair can affect power, cooling, air flow, software, research, crew schedule, or safety margins. Procedures must account for tools, restraints, connectors, replacement parts, testing, and possible secondary faults.

What does station aging mean for maintenance?

Aging increases attention to seals, structural loading, thermal cycling, obsolete parts, long-used equipment, and repeated maintenance demands. It does not automatically make the station unsafe. It does require careful monitoring, risk review, spare-parts planning, and decisions about which repairs remain appropriate near the end of planned operations.

How do ISS repair lessons help future space stations?

ISS repair experience shows that future stations need modular equipment, accessible parts, strong diagnostics, trained crews, reliable cargo delivery, and robotic maintenance options. Commercial stations will need repair systems that protect safety and preserve paid mission time. The ISS has provided decades of operational evidence for those design choices.

Appendix: Glossary of Key Terms

Air Revitalization System

The Air Revitalization System is part of the station’s life-support equipment. It helps maintain breathable cabin air by managing gases such as carbon dioxide and supporting air quality inside the pressurized modules where astronauts live and work.

Canadarm2

Canadarm2 is the Canadian-built robotic arm on the International Space Station. It moves along parts of the station, supports external maintenance, assists with cargo spacecraft operations, and can work with Dextre during station servicing tasks.

Corrective Maintenance

Corrective maintenance means repair work performed after equipment has broken, stopped working properly, or produced abnormal data. On the station, corrective work may involve troubleshooting, replacement, testing, cleaning, software steps, or coordination with ground specialists.

Dextre

Dextre is a Canadian two-armed robotic system designed for delicate external maintenance on the International Space Station. It can handle selected replacement tasks and reduce the need for astronauts to perform some work during spacewalks.

Environmental Control And Life Support System

The Environmental Control and Life Support System is the collection of equipment that helps keep the station livable. It manages air, water, pressure, oxygen, carbon dioxide removal, fire detection, waste handling, and related habitability functions.

Extravehicular Activity

Extravehicular activity means work performed outside a spacecraft, commonly called a spacewalk. On the ISS, astronauts conduct spacewalks for external maintenance, upgrades, inspections, equipment replacement, and tasks that cannot be completed from inside the station.

External Stowage Platform

An External Stowage Platform is an outside storage location used for large spare parts and equipment. Some external spares need power or thermal control so they remain usable until a robot or spacewalking astronaut retrieves them.

Microgravity

Microgravity is the condition in orbit where people and objects appear weightless because they are continuously falling around Earth. It changes how fluids move, how tools behave, how air circulates, and how astronauts perform repair work.

Mission Control

Mission Control refers to the ground teams that monitor spacecraft systems, support the crew, develop procedures, and guide operations. ISS mission control work is shared among NASA and international partner control centers.

Orbital Debris

Orbital debris is human-made material in Earth orbit that no longer serves a useful purpose. It can include fragments from rockets, satellites, explosions, collisions, or discarded hardware, and it poses a hazard to spacecraft.

Preventive Maintenance

Preventive maintenance is planned work intended to reduce the chance of future failure. On the station, it includes inspections, cleaning, filter changes, component checks, and replacement tasks scheduled before a system stops working.

Thermal Control

Thermal control is the management of heat so station equipment and crew areas stay within safe temperature limits. The ISS uses cooling loops, radiators, pumps, heat exchangers, and operational procedures to remove and redistribute heat.

U.S. Deorbit Vehicle

The U.S. Deorbit Vehicle is the spacecraft NASA selected SpaceX to develop for the controlled deorbit of the International Space Station at the end of its operations. Its purpose is to help guide reentry safely.

Water Recovery System

The Water Recovery System processes wastewater and humidity condensate into clean water for station use. It reduces the amount of water that must be launched from Earth and supports long-duration human spaceflight operations.