Astronauts Suni Williams and Butch Wilmore have recently returned to Earth after an unexpected nine-month mission aboard the International Space Station (ISS). Initially planned as an eight-day stay, the extended duration has implications for their health as they begin the recovery process. Prof Damian Bailey, a human physiology expert at the University of South Wales, remarked, “Space is by far the most extreme environment that humans have ever encountered and we’ve just not evolved to handle the extreme conditions.”

During their time in the microgravity environment of space, astronauts typically experience a range of physical changes, initially perceived as beneficial. Tim Peake, who flew to the ISS in 2015, described the experience saying, “It feels like a holiday. Your heart is having an easy time. Your muscles and bones are having an easy time. You’re floating around the space station in this wonderful zero-gravity environment.” This absence of gravitational force can mimic the effects of prolonged bed rest, which scientists often use to study the impact of zero gravity on the human body.

However, these benefits are short-lived. Muscle atrophy becomes a significant concern; astronauts must engage in approximately two hours of exercise daily, including a combination of treadmill training, cycling, and resistance workouts to mitigate muscle and bone loss. In conditions of microgravity, muscle strength diminishes rapidly, as the body does not require the same effort to maintain posture. Prof Bailey explained, “Every month, about 1% of their bone and muscles are going to wither away – it’s accelerated ageing.” Upon returning to Earth, astronauts may need assistance to exit their capsules, as observed in recent footage of Williams and Wilmore being helped onto stretchers.

Dr Helen Sharman, the first British astronaut, noted that while muscle mass recovery may take several months, regaining bone mass could be a more prolonged endeavour, potentially spanning “a couple of years.” She added that even after extensive recovery, there might be “subtle changes in the type of bone that we do rebuild after returning to Earth that may never return to completely normal.”

The physiological changes extend beyond muscle and bone. Astronauts often experience a shift in body fluids; instead of settling towards the lower limbs, fluids are redistributed towards the upper body and face, resulting in noticeable facial puffiness. Furthermore, this alteration can lead to cerebral swelling and visual disturbances. This phenomenon, termed “spaceflight-associated neuro-ocular syndrome,” can impact the optic nerve, retina, and possibly alter the shape of the eye, causing issues like blurred vision that may have irreversible consequences.

As Williams and Wilmore embark on their recovery journey, their experiences underscore the complex challenges faced by astronauts who venture into space, highlighting the need for comprehensive support systems as they transition back to life on Earth.

Source: Noah Wire Services