NASA astronauts Suni Williams and Butch Willmore return to Earth after a nine-month unexpected stay on the International Space Station. Credit: x-@moshede_
For most of us, staring at the Earth with space floating through it sounds like a dream.
However, for astronauts like Snie Williams and Butch Willmore, the experience has had serious physical consequences as they recently returned from an unexpected nine-month stay on the International Space Station (ISS).
“Space is the most extreme environment that humans have ever faced,” says Professor Damien Bailey, a physiology expert at the University of South Wales. “We’re not just evolving to deal with it.”
The effect of zero gravity on the human body
According to British astronaut Tim Peak, zero gravity may feel exhilarating at first – like an extended holiday – but the lack of gravity quickly causes the body to lose its strength and resilience.
In space, you don’t need to stand upright or support your weight. This results in rapid loss of muscle mass. As Professor Bailey said, “It’s a simple case of using it or losing it.”
The impact of space on muscle, bone and heart health
While it may look comfortable while floating within the ISS, your body is quietly deteriorating. Without gravity, even the heart and blood vessels become weaker over time, as they no longer have to resist the pull of the Earth. The same thing happens to the bones. The bones become brittle and lose density because they are not under constant load.
Space astronauts lose about 1% of their muscles and bone mass each month, and experts compare it to “accelerated aging.” By the time they return home, astronauts often need assistance to stand and walk, as seen when Williams and Wilmore are rescued by capsules and stretchers.
As a result, astronauts enter space at peak health peaks and stick to strict exercise routines while riding the ISS.
Still, as explained by Dr. Helen Shallman, the first British man in the universe, recovering is not a quick fix. “It can take months to regain muscle mass and years for the bone to be reconstructed. Still, some changes in bone structure may be permanent.”
More than just muscles: how the universe changes the whole body
The effects of microgravity do not stop in muscles and bones. SpaceFlight reshapes the body in an incredible way, from moving liquid upwards to astronauts with the classic “puffy face” appearance and altering the intestinal microbiome.
Perhaps more concerning is the pressure that causes inside the skull, leading to changes in the optic nerve and retina, contributing to the mystical “neuro-eye syndrome associated with space flight.” In some cases, astronauts experience blurred vision and long-term eye damage.
Balance is another issue. Microgravity distorts the vestibular system, the inner ear structure that causes spatial orientation. Without the concept of up and down, astronauts often feel disorientated in both space and when they return to solid ground.
“We could punish them the first two or three days before the planet,” Peak admits. “When your body tries to refit, you feel dizzy, weak and unstable.”
For Williams and Wilmore, the path to full recovery has only just begun. But their stories remind us that living in space is far from easy.
