
After spending over eight months aboard the International Space Station (ISS), Indian-origin NASA astronaut Sunita Williams and her colleague Butch Wilmore are set to return to Earth on March 19, 2025. The two astronauts have been stranded in space since June last year due to technical issues with Boeing’s Starliner spacecraft, which was supposed to bring them back much earlier. However, their return to Earth brings its own set of challenges, particularly the struggle of readjusting to gravity after prolonged exposure to microgravity.
The effects of long-duration spaceflight on the human body are well-documented, and for Williams and Wilmore, even simple tasks like lifting a pencil will initially feel like a strenuous workout. As they prepare for reentry, NASA is planning an extensive rehabilitation program to help them regain strength and adapt back to life on solid ground.
Astronauts who spend extended periods in space undergo significant physiological changes due to the lack of gravity. In microgravity, the human body adapts by redistributing fluids, weakening muscles, and reducing bone density. Upon reentry to Earth’s gravity, astronauts experience a sudden shift as fluids settle back into their lower extremities, leading to dizziness, swelling, and even temporary difficulties in movement.
As per reports, Butch Wilmore has openly discussed the difficulties astronauts face upon returning to gravity. “Gravity is de facto powerful, and that is what we feel after we get again,” Wilmore explained in an interview. He further added, “Fluids will be pulled down, and even lifting a pencil will feel like a exercise.” Sunita Williams has also acknowledged that readjusting to life on Earth will be a significant challenge, as her body will have to relearn how to function under gravity’s pull after months of floating weightlessly.
Spending extended time in microgravity leads to several physiological effects:
To mitigate some of the effects of microgravity, researchers have been exploring ways to strengthen astronauts’ bones and joints. A recent study published in npj Microgravity suggests that jumping exercises may help prevent cartilage damage and maintain bone strength in astronauts during long-duration missions. The study, conducted by researchers at Johns Hopkins University and the European Space Agency (ESA), found that mice subjected to jumping exercises had thicker and healthier knee cartilage, reducing the risk of long-term joint damage.
With future space missions aiming for Mars and long-term habitation on the Moon, preventing cartilage degradation is becoming a priority for space agencies. “Cartilage damage is a major issue that needs to be addressed despite being poorly understood,” said astrophysicist Marco Chiaberge, one of the study’s lead researchers. “The positive effect we saw in these mice was huge, and the magnitude of it was unexpected. Maybe astronauts could use similar training before their flight as a preventive measure.”
NASA has planned a rigorous rehabilitation program for Sunita Williams and Butch Wilmore upon their return. The process will involve: