How Do Astronauts Spend a Day in Space?

An astronaut’s day in space is an experience that constantly reminds one of humanity’s terrestrial origins while pushing the boundaries of existence toward the depths of the universe. Living in orbit bears no resemblance to any routine on Earth. Here, there is no dawn brightening the horizon nor complete darkness descending at night. On the International Space Station (ISS), which orbits Earth at a speed of eight kilometers per second, astronauts witness a new sunrise approximately every ninety minutes. This means that an astronaut sees the sun rise and set about sixteen times within every twenty-four-hour period.^【1】 However, the human body must remain anchored to its biological rhythm on Earth; otherwise, sleep patterns, attention span, and mental equilibrium are disrupted. For this reason, days aboard the station are scheduled according to Greenwich Mean Time, and every aspect of the astronauts’ lives follows a meticulously planned program down to the second.^【2】

When an astronaut wakes around six in the morning, the first thing they see through the window is the silent rotation of the blue planet below. Clouds glide like white silk over the continents, while the thin line of the atmosphere glimmers in sunlight. Yet life aboard the station leaves little room for emotion; every task is scheduled minute by minute. As soon as they wake, astronauts measure vital signs: heart rate, blood pressure, body temperature… Everything is recorded. Every minute spent in space provides scientific data on how the human body responds to these extraordinary conditions.

Astronauts Performing Personal Hygiene in Space (Generated by Artificial Intelligence.)

When it is time for personal care, the challenges of a microgravity environment become immediately apparent. Water behaves entirely differently here. Even a single droplet, if released freely, floats through the air as a small sphere and can collide uncontrollably with electronic devices. Therefore, astronauts clean their faces with damp wipes and wash their hair with no-rinse shampoo. Even brushing teeth becomes a small experiment: a small amount of water is squeezed onto the toothbrush, mixed with paste, and then the mouth is wiped clean with a damp cloth. Rather than spitting, they swallow the paste, because a floating droplet of liquid could enter the ventilation system and cause problems.

Breakfast serves both as an energy source and a morale booster. However, the act of eating in space has been entirely redefined. Astronauts’ food is stored in vacuum-sealed pouches and rehydrated with hot water before consumption. Menus typically consist of freeze-dried eggs, cereal flakes, fruit purees, protein bars, and powdered drinks. Due to microgravity, bodily fluids distribute more evenly throughout the body, leading to nasal congestion and a reduced sense of taste. For this reason, astronauts often add spicy sauces, mustard, or spices to their meals. NASA develops special menus to help astronauts maintain their palates; each country’s astronaut may also bring along certain traditional foods from their culture. Among the camp-style meals, one might find Japanese curry or Russian cereals and soups.^【3】

Food in Vacuum Pouches Consumed by Astronauts During Breakfast (Generated by Artificial Intelligence.)

After breakfast, a long and intense workday begins. The daily schedule is determined by task lists sent from ground control centers on Earth. Astronauts work as scientists, technicians, engineers, and even repair specialists aboard the station. On some days, they conduct biological experiments examining how human cells behave under microgravity; on others, they test new materials technologies. Experiments such as studying surface tension in liquids or how fire behaves in low-oxygen environments cannot be performed on Earth.

Maintenance of the station’s technical systems is also the astronauts’ responsibility. Dozens of small daily tasks are repeated regularly: replacing air filters, monitoring water recycling systems, checking the condition of solar panels, and testing communication systems.^【4】 In space, even the smallest malfunction can pose a life-threatening risk, so no detail is overlooked. Every task is a team effort; astronauts remain in constant communication with their ground team. All activities performed during the day are logged, images are transmitted to Earth, and engineers provide real-time feedback.

Astronauts Maintaining Technical Systems in Space (Generated by Artificial Intelligence.)

The most demanding aspect of life in space is the human body’s response to microgravity. Muscle mass decreases daily, bone density declines, and fluids accumulate in the head. To counteract these effects, astronauts must exercise for nearly two hours each day.^【5】 The station is equipped with a treadmill, a stationary bicycle, and a device called ARED that generates resistance through pistons to simulate weightlifting. To stay anchored to the treadmill, astronauts secure themselves with a special harness; otherwise, their feet would detach from the floor and bounce off the ceiling. The ARED system creates the sensation of lifting weights using piston resistance. These exercises are not only physically necessary but also psychologically essential. The silence of space, the isolated environment, and the constant discipline of duty can exert psychological pressure. Exercise not only strengthens the body but also keeps the mind alert. Astronauts often work to music and sometimes run while watching Earth pass below.

At designated times during the day, astronauts have scheduled communication windows with Earth. Each astronaut can have video calls with family members several times a week, send emails, or receive messages. Communication in space is not merely about exchanging information; it is vital for preserving the astronaut’s emotional well-being. NASA emphasizes that an astronaut’s morale directly affects mission performance. Therefore, every astronaut participates in psychological support sessions. In the boundless silence of space, it is not easy for a person to be alone with their inner thoughts. Talking to family, listening to a favorite piece of music, or celebrating a birthday on Earth via video call serve as powerful sources of morale for astronauts.

Astronauts Exercising in Space (Generated by Artificial Intelligence.)

As evening approaches, the fatigue of the day begins to show. Dinner is usually a quieter affair. Sometimes astronauts eat simultaneously with friends on Earth; other times, they eat in silence while gazing out the window. Outside, the night lights of cities on Earth glow below. The borders of Europe, the densely populated cities of India, the dark deserts of Africa, the dancing auroras at the poles… All these views simultaneously remind astronauts of humanity’s smallness and unity.

When it is time to sleep, each astronaut retreats into their individual sleep capsule. These capsules are small, quiet, and personal spaces containing a sleeping bag, a few photographs, and sometimes a book or a small memento. Astronauts fasten their sleeping bags to the wall; otherwise, they would drift while sleeping and collide with objects. Special lighting systems are used aboard the station to improve sleep quality. These systems mimic the natural daylight cycle on Earth to regulate the biological clock. Before falling asleep, most astronauts take one last look out the window. At that moment, the blue planet is passing beneath them. This fragile sphere, spinning in the darkness of space, remains both their home and their longing.

Astronauts Sleeping in Space (Generated by Artificial Intelligence.)

A day spent in space tests human resilience, adaptability, and curiosity at every moment. For astronauts, the meaning of a day goes beyond completing tasks. They are pioneers testing whether humanity can live permanently in space. Each morning, as they awaken, every step they take in microgravity represents a rehearsal for future lunar bases and journeys to Mars. These humans, drifting silently through the darkness hundreds of kilometers from Earth, quietly remind all of us of the same question: Can humanity survive elsewhere in the universe? Perhaps the answer to that question is being shaped right now, inside the silent capsule where an astronaut drifts peacefully into sleep.