Astronaut Sunita Williams, currently on an eight-month mission aboard the International Space Station (ISS) with fellow astronaut Butch Wilmore, offers fascinating insights into how the human body changes in space. In a recent interview, she discussed the impact of microgravity on astronauts, noting that they experience rapid hair and nail growth, temporary height increase due to spinal expansion, and a reduction in facial wrinkles. However, these effects are only temporary and return to normal once astronauts return to Earth. Williams also highlighted concerns regarding bone density and muscle mass loss, explaining astronauts’ strict exercise routines to counteract these issues.
Physical Changes in Space
Williams revealed that astronauts experience various physical changes while in space. She explained,
“Calluses on your feet disappear because you don’t walk, and I noticed my fingernails and hair grew faster. Without gravity, some wrinkles on your face might temporarily smooth out due to fluid shifting upwards. Your spine also expands because there’s no pressure on the cartilage between your vertebrae, making you slightly taller in space. However, these changes reverse once you return to Earth, and gravity takes over again. You shrink back to your normal height, your back might ache a bit.”
However, these changes are not permanent. Upon returning to Earth, astronauts revert to their normal height, often accompanied by some back discomfort as gravity takes its toll again.
Concerns About Bone Density and Muscle Mass
Another concern that Williams emphasized is the loss of bone density and muscle mass in space. “In microgravity, bones lose density quickly,” she noted. To combat this, astronauts adhere to rigorous exercise routines using specialized equipment. They use treadmills with harnesses to simulate gravity and lift weights to maintain muscle strength, particularly in the hips and legs. Exercise bikes are also used to support cardiovascular fitness.
To counteract this, we exercise rigorously with specialised equipment. We run on treadmills with harnesses to simulate gravity and lift weights to maintain muscle mass, particularly in the hips and legs. We also use exercise bikes for cardiovascular fitness.”
Radiation Exposure Risks
Despite NASA’s efforts to address these challenges, radiation exposure remains a significant risk. Cosmic rays and other radiation penetrate the spacecraft, subjecting astronauts to levels far higher than those on Earth. This exposure increases the risk of cancer and can potentially lead to acute radiation sickness.
