Imagine waking up every morning for a year while floating 400 kilometers above Earth, staring out at our blue planet from a window the size of a dinner plate. This is daily life for astronauts who spend extended missions aboard the International Space Station (ISS). Staying in space for a year isn't just about scientific milestones—it's a profound test of human resilience, teamwork, and curiosity. Both men and women have now joined this adventure, and their time in orbit has produced some of the most fascinating lessons about the human body, technology, and the universe itself.
What Does a Year Aboard the ISS Mean?
The ISS is a floating laboratory that orbits Earth every 90 minutes, which means astronauts witness 16 sunrises and sunsets each day. Missions lasting six months were once the standard, but a select few have achieved the ultimate challenge: an unbroken year in microgravity conditions. This marathon journey began gaining fame after American astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko completed the first official “One-Year Mission” from March 2015 to March 2016.
A year in orbit isn’t just about clocking hours—every day is meticulously scheduled with science experiments, spacecraft maintenance, exercise sessions, and communication with family. This experience helps space agencies from around the world prepare for even more ambitious missions, like sending humans to Mars.
Physical Challenges: How the Body Copes and Adapts
Living in microgravity means that astronauts’ bodies go through remarkable—and sometimes strange—transformations. Over a year, muscles can shrink and bones can lose density, so crew members must exercise for at least two hours every day just to maintain their health. NASA’s research has revealed that astronauts can lose up to 1-2% of their bone mass per month without proper exercise. So, on the ISS, treadmills are strapped to the floor, resistance machines mimic weightlifting, and cycling is done while floating.
The body’s fluids shift toward the head, causing a puffy “moon face” and sometimes affecting eyesight. Some astronauts report seeing flashing lights when they close their eyes, caused by cosmic rays hitting the retinas. The longer an astronaut spends in space, the more scientists learn about how these effects might impact future explorers—especially those planning to spend even longer on missions to the Moon or Mars.
Sleep can also be an adventure. The absence of a natural “up” or “down” means that astronauts drift into their sleeping bags, attached to the wall with Velcro. Despite following strict routines, the constant hum of equipment and the unusual environment often make restful sleep elusive. Yet, over the course of a year, astronauts become experts at adapting.
Mental Resilience: Keeping Spirits High
The psychological challenges of a year in space are as demanding as the physical ones. Imagine spending 365 days in a space smaller than a basketball court, rotating between work, meals, exercise, and sleep—all with a handful of teammates and no fresh air or privacy. Astronauts describe a unique camaraderie that develops “off planet,” but also admit to missing Earth's simple pleasures: rain, wind, and the company of their loved ones.
To help keep their spirits up, astronauts maintain regular communication with family and friends via video chats and emails. Recreational activities, like movie nights and special “space meals,” become eagerly anticipated treats. Birthdays and holidays are celebrated with creative flair—think floating cakes and digital “parties.”
Training to cope with confinement, monotony, and stress begins years before launch. Space agencies carefully select astronauts for their ability to work as a team and remain calm under pressure. Over a year, the close-knit crew often feels more like family than colleagues.
Scientific Benefits: Why a Year Makes a Difference
Spending a year on the ISS isn’t just a personal challenge—it’s crucial for scientific discovery. Long-duration missions provide a unique laboratory to study everything from the behavior of fluids in microgravity to the effects of space on the human genome. Scott Kelly, for instance, became half of a rare genetics experiment, as his identical twin, Mark Kelly, remained on Earth. Comparing the twins showed that 7% of Scott's gene expression was different from his brother’s even months after he returned, hinting at the deep biological impact of living in space.
The ISS crew runs hundreds of experiments, covering topics like plant growth, materials science, and medicine. Results have improved drugs for osteoporosis, introduced new techniques in robotics, and even advanced water purification systems that benefit communities on Earth.
Preparing for the Next Leap: Mars and Beyond
One-year missions act as a rehearsal for humanity’s next great adventure: traveling to Mars. Any journey to the Red Planet will require astronauts to spend up to three years away from Earth, so understanding how bodies and minds adjust over an entire year is a critical first step. The ISS offers a rare opportunity to test life-support systems, develop emergency procedures, and perfect the art of remote teamwork—all of which will shape the future of space travel.
These extraordinary years aboard the ISS remind us what humans can achieve when we reach beyond our home planet. Through curiosity, courage, and international collaboration, astronauts living a year in space don't just change our understanding of the universe—they also expand the boundaries of what is possible for us all here on Earth.