Astronauts’ Return: The Lasting Impact of Space on the Human Body

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NASA astronauts Sunita Williams, 59, and Butch Wilmore, 62, along with 2 more astronauts have finally returned to Earth on 18th of March after an extended nine-month stay aboard the International Space Station (ISS). What was initially planned as a brief nine-day mission turned into a prolonged spaceflight due to issues with their Boeing Starliner spacecraft.

The duo made their way back safely, landing in the SpaceX Dragon capsule off the coast of Florida.

Both astronauts are highly experienced in space travel, but spending 270 days in micro-gravity will have left lasting effects on their bodies. TISHHA news brings the health challenges they may face post-mission.

The Physical Impact of Prolonged Space Travel

British astronaut Tim Peake, speaking to ABC Australia, noted that upon returning to Earth, astronauts often experience nausea, dizziness, and vertigo as their bodies readjust to gravity. Their muscles and bones must also adapt to the increased strain of standing and walking again. Peake estimated it would take around two to three months for Williams and Wilmore to fully recover and rebuild muscle strength, particularly in the lower back.

Frank Rubio, a NASA astronaut who spent 371 days in space, described his post-mission recovery as a months-long process of reintegration and rehabilitation. In a 2023 media interview, he explained that while astronauts adapt quickly to space conditions, readjusting to Earth’s gravity can be a longer and more challenging process.

How Space Affects the Human Body

Astronauts returning from extended spaceflights often experience physiological changes, some of which may have long-term consequences.

Muscles: In micro-gravity, muscles deteriorate, especially in the back, neck, thighs, and calves. Even with exercise, muscle loss occurs at a faster rate than on Earth. A 2021 study in the Systematic Review journal found that current exercise routines in space are insufficient to completely prevent muscle loss.
Bones: Without gravity, weight-bearing bones lose about 1–1.5% of their mineral density per month in space. While rehabilitation helps restore some of this loss, bone density may not fully recover. Additionally, calcium released from deteriorating bones can lead to kidney stones. A 2022 study found evidence of significant bone loss in astronauts who had spent an average of five and a half months on the ISS.
Vision: Some astronauts develop a condition known as Spaceflight Associated Neuro-Ocular Syndrome (SANS), in which fluid shifts in the body due to micro-gravity affect the eyes and vision.
Genetics: While most genetic changes caused by space travel revert after astronauts return to Earth, approximately 7% of these alterations remain permanent.
Cognitive Function and Mental Health: Exposure to space radiation may damage the brain and increase the risk of Alzheimer’s disease. The lack of gravity can also disrupt spatial orientation and induce motion sickness.
Cardiovascular Health: Blood circulation slows in micro-gravity, red blood cell production decreases, and heart rhythm irregularities become more common.

Recovery After Returning to Earth

Once astronauts are back on Earth, their bodies gradually readjust to gravity, though full recovery can take months.

After One Week: Motion sickness, dizziness, and balance issues typically subside. Sleep patterns normalize.
After Two Weeks: The immune system strengthens, and fluid levels lost in space are restored.
After One Month: Muscles regain most of their pre-flight strength.
After Three Months: Skin regeneration is nearly complete, and body mass returns to normal. However, astronauts may still have a higher risk of bone fractures and long-term health concerns such as cancer, nerve damage, and degenerative diseases.