Astronauts Suni Williams and Butch Wilmore have returned to Earth after spending nine months aboard the International Space Station (ISS). Their mission was originally planned for only eight days but was extended significantly. Now, they must face the physical challenges of recovering from long-term space travel.
Many people dream of seeing Earth from space, but the reality of living in a microgravity environment is much more challenging than expected. Humans evolved to function in Earth’s gravity, and extended periods in space can cause changes to the body that take years to fully recover from.
The Challenges of Space Travel: A New Frontier for the Human Body
“Space is the most extreme environment humans have encountered, and we have not evolved to handle these conditions,” says Professor Damian Bailey, a human physiology researcher at the University of South Wales. Space travel causes many changes to the human body, and most become apparent only after returning to Earth.
Initially, astronauts feel a sense of exhilaration. Astronaut Tim Peake, who visited the ISS in 2015, described it as a “holiday” where “your heart has an easy time” and muscles and bones face no strain from gravity. Floating through the space station in a zero-gravity environment is incredible, but the long-term effects on the body are serious.
Muscle and Bone Loss in Microgravity
In space, muscles and bones weaken because gravity is absent. On Earth, standing up requires multiple muscles to work together. This effort is unnecessary in space. The result is that muscles lose strength, and bones become brittle. Additionally, the heart and blood vessels weaken because they no longer need to pump blood against gravity.
“Every month, astronauts lose about 1% of their bone and muscle mass—it’s like accelerated aging,” explains Professor Bailey. This rapid decline in bone and muscle mass is one of the most noticeable effects of long-term space travel.
Upon returning to Earth, astronauts often require assistance to exit the spacecraft and adjust to gravity. To mitigate these effects, astronauts are in peak physical condition before their missions. They also exercise for two hours daily in space, using treadmills, cycling machines, and weights to slow muscle and bone loss.
Suni Williams and Butch Wilmore now face the challenge of rebuilding their strength. “It will probably take them a few months to rebuild muscle,” says Dr. Helen Sharman, the first Briton in space. However, bone mass recovery could take “a couple of years,” and some changes may never fully reverse.
The Impact of Space on the Gut and Other Body Systems
Space travel also affects the microbiome—the bacteria that live in the gut. Scientists have found that the balance of gut bacteria changes in microgravity, though the long-term effects are still unclear.
Changes in the Brain and Senses
Body fluids shift in space. On Earth, gravity pulls fluids toward the lower body. In space, fluids move toward the chest and head, causing puffiness in the face. Fluid shifts can also affect the brain and cause vision problems, such as blurred sight or permanent damage to the optic nerve, retina, and eye shape. This condition is known as “spaceflight-associated neuro-ocular syndrome.”
The vestibular system, which controls balance and spatial awareness, is also disrupted. Without gravity, there is no clear “up,” “down,” or “sideways.” This disorientation is particularly challenging for astronauts returning to Earth. Tim Peake describes the difficulty in adjusting to gravity. “The first phase of getting rid of dizziness, regaining balance, and walking normally takes two or three days,” he says. “Those first days back on Earth can be really tough.”
The Road to Recovery
After returning to Earth, Suni Williams and Butch Wilmore will begin their recovery journey. They will undergo a rehabilitation program to regain their strength. It will take time, but with the right support, they will recover. However, space travel’s impact on the body remains significant, and some changes may never fully reverse.
Space exploration is remarkable, but it presents unique challenges for the human body. Astronauts like Suni and Butch face a long road to recovery as they adjust to life back on Earth. However, their experience remains a powerful testament to human exploration.