Space flight is a strenuous activity for the human body, with the astronauts exposed to a range of challenges such as radiation exposure, microgravity stress, and the psychological impact of extended isolation. As missions push further beyond Earth's orbit, like future trips to the Moon or Mars, the astronauts will be exposed to even greater risks to their health. Sunita Williams, a famous astronaut, has reported her experiences on the International Space Station (ISS), providing useful information regarding the physical and psychological stress of long-duration missions.
Sunita Williams' have been stuck in space for over 7 months now on the International Space Station (ISS) which have brought light to the high health risks being faced by the astronauts on long-duration space flights. Under microgravity, astronauts such as Williams lose bone density, undergo muscle atrophy, and experience vision alterations as a result of fluid shifts that raise intracranial pressure, leading to Spaceflight-Associated Neuro-Ocular Syndrome (SANS). Space radiation exposure also increases risks like cancer, DNA damage, and cardiovascular complications. Psychologically, long-term isolation and confinement in space result in sleep disorders, stress, and mood disorders. Nevertheless, astronauts such as Williams are resilient, yet recovery upon their return to Earth is complicated with residual health concerns like muscle and bone loss.
Why is space travel challenging for the astronauts
The human body evolved over millions of years to thrive in Earth's environment, which includes its gravity, atmospheric composition, and relatively low radiation levels. However, space travel exposes individuals to a drastically different environment, presenting various physiological and psychological challenges, particularly with extended exposure, as noted by Afshin Beheshti, director of the Center for Space Biomedicine at the University of Pittsburgh.
As researchers work on developing new countermeasures to safeguard space travelers, more data is required on astronauts with diverse health backgrounds and who are engaged in different types of missions. This will help create personalized risk profiles and mitigation strategies, according to Chris Mason, a professor of physiology and biophysics at Weill Cornell Medicine in New York.
Hazards of space radiation and its impact on astronaut health
On our planet, our atmosphere and magnetosphere protect us from the damaging radiation of space radiation by serving as a natural shield. Space astronauts are exposed to high levels of cosmic radiation that damage DNA, induce cancer, and result in neurodegenerative disorders. The radiation influences the cardiovascular and immune systems and results in long-term complications. For any space mission beyond low-Earth orbit, for example to the moon or Mars, the astronauts would be subjected to even higher doses of radiation, significantly increasing these risks to their health, and possibly impairing mission success. The challenge of reducing these risks is paramount to future space travel.
Impact of microgravity
Microgravity, or weightlessness, has a significant impact on the human body. Without the steady tug of gravity in one direction, body fluid flows in the direction opposite to gravity, puffing up the face and creating intracranial pressure, which decreases vision. Bones and muscles, normally made healthy through the tug of gravity, experience bone density loss and muscle weakness in microgravity. The cardiovascular system also experiences a significant loss, like an inability to maintain blood pressure during reentry on Earth. The vestibular system for balance and coordination also gets impaired with long-term exposure to microgravity and results in spatial disorientation and movement problems.
Psychological and physical challenges of spaceflight on astronauts
Other than physical stress, spaceflights also pose monumental psychological challenges on account of being in close confinement and tight living quarters of space vehicles and orbital space stations. Reduced socialization and stimulation from nature can have sleep disturbances, cognitive deficits, and affective disorders. The prolonged exposure of being in confinement spaces—such as on the ISS or an eventual mission to Mars—only aggravates conflict between people, affecting mental status and mission outcomes.
Recovery from spaceflight also varies according to the duration of the flight. Those returning from short-duration flights recover totally, and most of the impairment in their bodies is reversed in a few days. Those on board for many months, for example, crew members on the ISS, take longer to recover. While most of the physiological systems normalize, signs such as Spaceflight-Associated Neuro-Ocular Syndrome (SANS), affecting vision due to fluid shifts and intracranial pressure, may remain. Some of the astronauts need corrective glasses or other intervention for irreversible damage.
Effects of spaceflight on reproductive health of astronauts
A major gap in the understanding is the impact of spaceflight on human reproduction and fetal development, according to Beheshti. Research on reproductive health in space has been limited, primarily involving animals like mice. The full effects on human fertility, embryonic development, and the feasibility of long-term space habitation across generations are still unclear. This knowledge gap is particularly crucial as humanity looks towards potential future space colonization.
Recent health findings from space travel and their impact
Recent research has found many health effects that astronauts undergo during space travel. In 2024, a study of SpaceX Inspiration4 crew members found changes in brain function, heart function, muscle mass, kidney function, and immune regulation. Another study found ISS astronauts to be more susceptible to headaches than previously believed, with the majority of them developing it during space residence. Other research has also demonstrated the increase in cerebral ventricles in astronauts, a symptom of a change in brain fluid dynamics in long-duration missions.
Also Read | Watch: NASA astronaut Don Pettit’s video of water droplets orbiting a needle in space stuns internet – “Zero gravity is so dope”