Space missions lasting months or even years can take a surprising toll on the human body, altering muscles, bones, vision, and even gut bacteria.
As space agencies plan longer missions, understanding these effects is crucial for future space exploration.
Muscles and bones: The gravity challenge
In the microgravity of space, muscles and bones rapidly weaken. Postural muscles like those in the back, neck, calves, and quadriceps can lose up to 30 percent of their mass during missions lasting three to six months.
Bone mass also diminishes by 1-2 percent per month, increasing fracture risks. Astronauts counteract these effects by exercising for 2.5 hours daily using resistance devices, treadmills, and bikes. Yet, studies show that even intense workouts might not fully preserve muscle function, prompting research into more effective regimens.
Weight, height, and gut changes
Space travel affects weight and height differently. NASA astronaut Scott Kelly lost 7 percent of his body mass during his 340-day stay on the ISS, while his gut bacteria underwent significant changes.
Factors such as altered diets, radiation, and physical activity levels could play a role. Astronauts also tend to grow taller in space as spinal discs expand, but this can lead to back pain and complications upon return.
Vision and brain: The impact on cognition
Prolonged exposure to microgravity affects blood distribution, causing fluids to accumulate in the head and pressure to build up behind the eyes, leading to vision issues. Some changes, like swelling of the brain's ventricles, can persist for years after return.
Studies on astronauts have also shown slight decreases in cognitive performance post-flight, likely as the brain readjusts to gravity.
Genetic and immune system alterations
Space travel appears to lengthen telomeres—protective caps on DNA strands—but they shorten rapidly upon return to Earth. This phenomenon, observed in Scott Kelly, may stem from radiation exposure or the body’s stress response. Research also indicates that spaceflight can alter gene expression related to inflammation, bone formation, and immune response, with male astronauts appearing more sensitive to some immune changes than females.
Looking ahead
Understanding these bodily changes is essential as humanity eyes deep-space missions, like a potential 1,100-day round trip to Mars. Insights from astronauts like Frank Rubio, who spent 371 days aboard the ISS, are guiding preparations for these ambitious journeys.
Despite the challenges, continuous research will help make long-duration space travel safer and more feasible.
Courtesy: BBC
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