What Is It Like to Live On the International Space Station?

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The International Space Station (ISS) represents a pinnacle of human engineering and international collaboration. It is a permanently inhabited laboratory, research outpost, and home that circles the Earth every 90 minutes at over 17,000 miles per hour. For the handful of astronauts and cosmonauts who live aboard, life is a meticulously scheduled and physically demanding experience, governed by the extraordinary principles of physics in a microgravity environment.

Living on the ISS is an existence defined by adaptation. It’s a place where “up” and “down” are abstract concepts, where the air is manufactured, and where water is a resource so precious it’s recycled from human breath. For crews on long-duration missions, typically lasting six months, the station becomes their entire world – a bustling, humming, and isolated bubble of life suspended 250 miles above the planet they are charged with studying. This article explores the day-to-day reality of that life, from the moment of waking to the complex work of science and survival.

The Daily Rhythm: A 24-Hour Cycle in 90 Minutes

While the station experiences 16 sunrises and 16 sunsets each day, the crew does not. Life is regimented by a strict 24-hour schedule based on Coordinated Universal Time (UTC), which serves as a compromise for the global partners managing the station from Mission Control Centers in Houston (Johnson Space Center) and Moscow (Roscosmos).

Waking Up in Weightlessness

A typical workday begins around 6:00 AM UTC. There is no gentle morning light; the crew quarters are windowless to allow for a regulated sleep schedule. Astronauts wake up to an alarm, often set on a watch or laptop.

Sleep itself is an unusual experience. Each astronaut has a private Crew Quarters, a sound-dampened cubicle about the size of a public phone booth. There are no beds. Instead, astronauts wriggle into a sleeping bag that is tethered to the wall. This is necessary to prevent them from drifting while asleep and bumping into sensitive equipment. Some astronauts prefer to tether their sleeping bag horizontally, while others sleep vertically.

The environment is never truly silent. The station is alive with the constant hum of fans, pumps, and filters from the Environmental Control and Life Support System (ECLSS). This background noise is essential for life; without active air circulation, a sleeping astronaut could suffocate in the bubble of their own exhaled carbon dioxide.

Once awake, the first challenge is simply getting out of the sleeping bag. Astronauts emerge from their quarters, not by “getting up,” but by “getting out” – pulling themselves into the central corridor. They float to the station’s “bathroom” for morning hygiene. This involves using a wet towel with a small amount of no-rinse soap, as there are no showers. Brushing teeth is also an exercise in water management; astronauts use a minimal amount of water and either swallow the toothpaste foam or spit it into a towel.

A Sample Workday

The crew’s schedule is planned with military precision by ground controllers. Each astronaut has a personalized itinerary, often planned down to 5-minute increments, which they access on station-based laptops. A typical weekday is a dense mixture of scientific research, station maintenance, exercise, and crew conferences.

Here is a representative schedule for one crew member:

Twice a day, the entire crew gathers for a Daily Planning Conference (DPC) with the various mission control centers on Earth. These video conferences are the primary way to synchronize the day’s activities, troubleshoot problems, and maintain a direct line of communication with the ground teams at NASA, Roscosmos, JAXA, ESA, and the CSA.

The Job: Science and Maintenance

The ISS is, above all, a laboratory. A large portion of an astronaut’s day is dedicated to conducting scientific experiments that are impossible to perform on Earth. This research spans biology, human physiology, physics, and astronomy.

Crews might spend the morning collecting their own blood and urine samples to be analyzed back on Earth, helping scientists understand the body’s response to long-duration spaceflight. They might operate the Microgravity Science Glovebox, a sealed container that allows them to safely manipulate fluids, flames, or biological specimens without letting them float away.

In a fluid dynamics experiment, for example, the absence of gravity means that the properties of surface tension and capillary action dominate. Understanding these effects is not just academic; it helps design better fuel systems for future spacecraft. Similarly, studying combustion in microgravity reveals how fire spreads without buoyancy, information that improves fire safety on Earth and in space.

The other half of the job is maintenance. The ISS is a highly complex machine, essentially a “building” that is also a spacecraft, and it requires constant upkeep. This is not always glamorous work. It includes tasks like:

• Cleaning filters: The station’s air and water filters are vital. Crews regularly vacuum air intake grilles, which often become a “lost and found” for small items that have floated away.
• Repairing systems: This can be as complex as replacing a refrigerator-sized pump module or as simple as fixing a broken piece of exercise equipment.
• Plumbing: The station’s water and waste systems are a network of pumps and tubes that require periodic servicing.
• Housekeeping: Every week, typically on Saturday morning, the crew performs collective housekeeping. They wipe down surfaces with disinfectant, vacuum the “floors” (which are just walls), and collect trash. This is essential to control mold, bacteria, and floating debris.

The Physical Experience of Microgravity

The most defining characteristic of life on the ISS is the persistent state of weightlessness. This “free-fall” environment changes everything about how a person moves, perceives their body, and interacts with their surroundings.

Learning to Move

On Earth, movement is a constant battle against gravity. In space, the primary force to manage is inertia. It takes very little effort to push off a wall and soar “Superman-style” down the length of a module. The challenge is stopping. New arrivals to the station are often seen over-shooting their destination or tumbling, as they haven’t yet learned to master their momentum.

Veteran astronauts move with a practiced, spider-like grace. They use fingertips to push off surfaces, controlling their trajectory and velocity with precision. They learn to anchor their feet in restraints on the floor (or walls) to provide leverage when working with tools. They must be mindful of their crewmates; a careless push can send someone else pinwheeling in the opposite direction.

This environment is also a logistical challenge. Every item must be tethered, stowed in a bag, or attached to a wall with Velcro or double-sided tape. A simple task like laying out tools for a repair job becomes a complex affair. A bolt that slips from an astronaut’s hand will not fall; it will drift away, potentially lodging itself in a ventilation system or behind a critical electronics panel.

The Body’s Response to Weightlessness

The human body is exquisitely adapted to Earth’s gravity. Removing that persistent 1-G force has immediate and significant physiological consequences.

The first and most immediate effect is a massive fluid shift. On Earth, gravity pulls blood and other bodily fluids down into the legs. In space, this pull vanishes. Bodily fluids redistribute, moving from the lower body to the upper body, chest, and head. This leads to the characteristic “puffy face” and “bird legs” seen in astronauts. This fluid shift also causes a feeling of congestion, similar to a constant head cold, which can dull the senses of smell and taste.

Many astronauts also experience space adaptation syndrome (SAS), or “space sickness,” during their first few days. The brain’s vestibular system, which controls balance, receives conflicting information from the eyes and inner ears. The eyes report a “room” that is tumbling, while the inner ear feels no corresponding motion. This disconnect can cause intense nausea, disorientation, and vomiting.

Over the long term, the changes are more systemic. Without the constant load of gravity, the body begins to shed tissues it noS longer thinks it needs.

• Muscle Atrophy: Muscles, especially the large postural muscles in the back and legs, begin to waste away.
• Bone density loss: The skeleton, no longer needing to support the body’s weight, stops maintaining itself. Astronauts can lose bone density at a rate of 1% to 2% per month in space, a condition similar to accelerated osteoporosis.
• Cardiovascular Changes: The heart, no longer needing to pump blood “uphill,” can shrink slightly in size.

A more recently discovered issue is Space-Associated Neuro-ocular Syndrome (SANS). The fluid shift appears to increase pressure in the skull, which can physically change the shape of an astronaut’s eyeball, leading to vision problems that can persist after returning to Earth.

Life Support: The Essentials of Survival

The ISS is a hermetically sealed environment. Every breath of air, sip of water, and degree of temperature is a product of complex, interconnected machinery.

Breathing Easy

The station’s atmosphere is maintained at the same pressure (14.7 psi) and composition (roughly 78% nitrogen, 21% oxygen) as Earth at sea level. The oxygen itself is primarily generated through a process of electrolysis. The station’s Oxygen Generation System uses solar-generated electricity to split water into its component parts: hydrogen, which is vented into space, and oxygen, which is released into the cabin. Backup systems include pressurized oxygen tanks and solid-fuel “oxygen candles,” which release oxygen through a chemical reaction.

Just as important as adding oxygen is removing carbon dioxide (CO2). The station’s CO2 scrubbers, part of the ECLSS, are constantly filtering the air. This system is one of the loudest and most vital on the station.

Air circulation is also a life-or-death matter. On Earth, warm air (like exhaled CO2) rises, and cool air sinks, creating natural circulation. In microgravity, this “convection” does not happen. An astronaut remaining still could be enveloped in a bubble of their own CO2. To prevent this, fans are always running, creating a constant breeze that mixes the air and ensures it gets scrubbed properly.

Water: The Ultimate Recycled Resource

Water is one of the heaviest and most expensive resources to launch from Earth. A single liter costs thousands of dollars to transport. As a result, the ISS features a “closed-loop” Water Recovery System (WRS) that is a marvel of engineering.

The WRS collects water from every possible source:

• Humidity from the air (including crew breath and sweat)
• Wastewater from hygiene (hand-washing, oral hygiene)
• Urine

This combined wastewater is sent through an advanced purification process. It’s filtered, distilled, and passed through catalytic reactors. The result is water that is, by many standards, cleaner than most municipal tap water on Earth. The station’s WRS can recycle about 93% of all water. The phrase “yesterday’s coffee is tomorrow’s coffee” is a popular and accurate joke among the crew.

Regulating Temperature and Pressure

Outside the station, temperatures swing wildly from over 250°F (121°C) in direct sunlight to -250°F (-157°C) in shadow. The station is protected by a multi-layer insulation (MLI) blanket that acts like a high-tech thermos.

The primary challenge is not staying warm, but getting rid of excess heat. The station’s electronics, scientific equipment, and the astronauts’ own bodies generate a constant supply of heat. This heat is collected by internal water-cooling loops and transferred to an external system. This external system uses ammonia, a highly efficient (but toxic) coolant, which is pumped through massive radiators on the station’s truss to radiate the excess heat into the blackness of space.

Daily Life and Hygiene

The mundane tasks of daily living are transformed by microgravity into complex, and sometimes frustrating, procedures.

Eating in Orbit

There are no refrigerators for food storage (save for small units for scientific samples), so most food is shelf-stable. The menu is surprisingly diverse, with contributions from all the partner agencies. Astronauts select their menus months before flight.

Food comes in several forms:

• Thermostabilized: Heat-treated food in pouches, similar to military MREs (Meals, Ready-to-Eat).
• Rehydratable: Freeze-dried foods and beverages (like coffee, tea, and juice) that require adding hot or cold water.
• Natural Form: Nuts, tortillas, and candies.
• Irradiated: Meat items, like steak or turkey, that are sterilized with radiation.

Food preparation happens in the “galley” area. There are no stoves or microwave ovens (though a food warmer is used). The primary tool is a water dispenser that provides hot or cold water to rehydrate pouches.

Eating itself requires technique. Food is “sticky” by design. Sauces and gravies help keep food on a utensil. Tortillas are favored over bread because they don’t produce crumbs. Crumbs are a serious hazard in space, as they can be inhaled or float into sensitive electronics.

Drinks don’t “pour” from a cup. They are consumed from special pouches with straws or from “capillary cups” that use surface tension and a special shape to guide the liquid to the rim. Because of the fluid shift that dulls taste, many astronauts crave spicy and flavorful foods. Hot sauce is a prized commodity.

Keeping Clean

Personal hygiene is a daily challenge. Since there is no shower, astronauts take “sponge baths” using towels and a small amount of water. They use a “no-rinse” shampoo to wash their hair, applying it, working it into the scalp, and then “rinsing” by vigorously towel-drying. Any water droplets that escape must be caught with a towel before they float away.

Shaving is done with an electric razor that has a built-in vacuum to suction up the tiny whiskers. Fingernail trimming is also a careful operation, usually done over an air vent to catch the clippings.

The Space Toilet

The most frequently asked question is about the toilet. The station’s Waste and Hygiene Compartment (WHC) is an engineering solution to a complex problem. The system relies on airflow, not water, to function.

There are two separate systems:

1. Liquid Waste (No. 1): Astronauts (both male and female) use a funnel attached to a hose. A fan creates suction to draw the urine away from the body and into a collection tank. This urine is then sent to the Water Recovery System to be turned into drinking water.
2. Solid Waste (No. 2): This system is more like a camping toilet. The “bowl” is a very small opening, about the size of a dinner plate. Astronauts must position themselves precisely over it, using thigh-straps and hand-holds to secure themselves. When activated, a fan creates suction to pull the waste into a collection bag. Each time, a new bag is used. When full, these bags are compacted into a container, which is eventually loaded onto an uncrewed cargo ship (like a Cygnus or Progress vehicle) that burns up upon re-entry into Earth’s atmosphere.

Using the space toilet requires training and practice on Earth. It is a system that demands precision and is a frequent source of maintenance tasks.

Health and Fitness: Countering Microgravity

To combat the severe physiological effects of weightlessness, every crew member must follow a rigorous exercise regimen. Astronauts are scheduled for 2.5 hours of exercise every day. This is not considered free time; it is a vital medical countermeasure.

The station is equipped with three main exercise devices:

• TREAD (Treadmill with Vibration Isolation and Stabilization): This is a treadmill for running. To use it, astronauts must wear a harness with straps and bungees that pull them “down” onto the running surface, simulating body weight. This provides the impact and load-bearing that is essential for bone health.
• CEVIS (Cycle Ergometer with Vibration Isolation System): This is a stationary bike. It has no seat, as one isn’t needed. Astronauts just clip their shoes to the pedals and can orient themselves in any direction they find comfortable.
• ARED (Advanced Resistive Exercise Device): This is the most important machine for muscle and bone health. Since simple weights would be weightless, ARED uses a system of vacuum cylinders and flywheels to create resistance. Astronauts can perform squats, deadlifts, bench presses, and over 30 other exercises, simulating lifting hundreds of pounds.

These workouts are intense and are a major part of an astronaut’s day. Without them, an astronaut returning to Earth after six months would be so weak they might be unable to walk.

The View and The Mind: Psychological Life

A six-month mission in a confined space with a small group of people, far from family, is psychologically demanding. Managing the mental health of the crew is as important as managing their physical health.

The Cupola: A Window on the World

The most popular spot on theD ISS is the Cupola, a seven-windowed, dome-shaped module that faces the Earth. It provides a panoramic view that is a constant source of wonder and relaxation.

From the Cupola, astronauts can watch the Earth pass by. They see lightning storms from above, the swirling patterns of hurricanes, the thin, glowing line of the atmosphere, and the shimmering green and red curtains of the aurora. At night, cities glow in intricate, web-like patterns.

This experience is often described as the Overview Effect. Seeing the Earth as a single, borderless, and fragile entity floating in the blackness of space can be a powerful experience, giving many astronauts a new perspective on their home planet.

Staying Connected

Ground teams work hard to keep the crew connected to life on Earth. Astronauts have access to a station “internet” via satellite, which allows them to send and receive emails (synced periodically). They have an IP (Internet Protocol) phone they can use to make calls to any number on Earth.

The most valued connection is the weekly Private Video Conference. This is a secure video call where astronauts can speak to their families in private. Crews also celebrate holidays and birthdays together, decorating the modules and sharing special food sent up on resupply missions.

This multinational environment fosters a unique “expeditionary” culture. Crews are often a mix of Americans, Russians, Europeans, Japanese, and Canadians. The official languages are English and Russian, and many astronauts learn “Runglish,” a functional mix of the two. Eating meals together is an important social ritual, a time to relax, share stories, and bond.

The Ultimate Task: The Spacewalk

Perhaps the most challenging and dangerous job an astronaut can perform is an Extravehicular Activity (EVA), or spacewalk. An EVA is scheduled when a task – such as installing new equipment, repairing a component, or routing cables – must be done on the outside of the station.

Preparing for an EVA

A spacewalk is a marathon that begins days, or even weeks, in advance with procedure reviews and tool preparation. The spacesuit, or Extravehicular Mobility Unit (EMU), is not just clothing; it is a personalized, human-shaped spacecraft. It provides oxygen, power, temperature control, and protection from the vacuum and extreme temperatures of space.

On the day of the EVA, the spacewalkers begin a lengthy “pre-breathe” protocol. They “camp out” in the Quest Joint Airlock at a lower pressure and breathe pure oxygen for hours. This purges the nitrogen from their bloodstream to prevent decompression sickness (the “bends”) when they move to the lower-pressure environment of the suit.

Working Outside

An EVA typically lasts between six and eight hours. Spacewalkers always work in pairs and are alwaystethered to the station. Their primary tether provides life support and communications, and a secondary safety tether ensures they can’t float away.

Working in a pressurized suit is physically exhausting. The suit is stiff, and every movement is a fight against the pressure. Hand fatigue is a major issue. The work is slow, deliberate, and high-stakes. Dropping a tool is a significant problem, as it can become a piece of high-velocity orbital debris.

The environment is hostile. The vacuum is instantaneous, and the temperature swings are extreme. But the view is unparalleled: the entire Earth below, the station stretching out in all directions, and the blackness of the cosmos above.

Safety and Emergencies

The ISS is a safe environment, but it is an unforgiving one. The crew is trained relentlessly for three main emergency scenarios: fire, depressurization, and a toxic atmosphere (like an ammonia leak from the cooling system).

• Fire: This is the most feared scenario. In microgravity, fire burns differently, and smoke doesn’t rise. The crew must quickly use CO2 extinguishers or water-mist extinguishers to put it out.
• Depressurization: A leak, perhaps from a micrometeoroid impact, would cause the station’s air to rush out. The crew must identify the leak, seal off the affected module, and, if necessary, evacuate.
• Toxic Atmosphere: An ammonia leak would require the crew to don gas masks and move to the “safe haven” of the Russian Orbital Segment, which has a separate life support system.

For any “red alert” emergency, the crew’s “lifeboats” are always docked and ready. The Soyuz and Crew Dragon vehicles that ferry crews to the station remain attached, powered up, and capable of evacuating the entire crew and returning them to Earth within hours.

Summary

Life on the International Space Station is a study in contrasts. It is an experience of significant beauty and significant discomfort. It is a highly structured, demanding, and technical job that is also a deeply human and psychological journey. Astronauts are at once researchers, plumbers, mechanics, doctors, and explorers.

They live inside a machine that provides their every breath and recycles their every drop of water. They float through their day, working on experiments that push the boundaries of science while meticulously managing the mundane details of hygiene and trash collection. They are isolated from humanity, yet they are perhaps the most visible representatives of it, looking down from their window in the Cupola.

The ISS is a temporary home, a stepping stone on the human path to deeper space exploration toward the Moon and Mars. The daily lives of its residents are a continuous experiment, teaching us not just about science, but about how humans can adapt, survive, and even thrive in the most extreme environment we have yet inhabited.