When NASA astronauts Butch Wilmore and Suni Williams returned to Earth this month, they were greeted with a warm reception. However, since their return, concerns have arisen regarding their health.
The astronauts might face several challenges post-mission, ranging from mental health struggles to exposure to significantly higher levels of radiation compared to those on Earth. Additionally, the effects on their brain function are a consideration, but it is their bone health that is raising the most concern.
Their journey began on June 5, 2024, intended as an eight-day mission aboard the International Space Station (ISS). However, due to unexpected circumstances, their brief venture extended to nearly 300 days in space.
The extension was caused by multiple malfunctions of the Boeing Starliner they traveled on, such as five helium leaks, failures of five maneuvering thrusters, and an issue with a propellant valve.
During the 286 days in space, the lack of gravity exerted significant stress on their bodies.
A study released this month examined the effects of space on mice that were sent to the ISS, shedding light on the potential risks astronauts might face upon their return, particularly concerning bone health.
The experiment involved sending mice into orbit for 37 days and analyzing their skeletons once back on Earth.
Researchers from NASA and the Blue Marble Space Institute of Science emphasized, “A specific focus of our study is the femur because of its major weight-bearing role in the mouse.”
In a weightless environment, rapid bone loss in mammals has been associated with both microgravity and radiation, though the exact mechanisms remain uncertain.
The study assessed whether microgravity was primarily responsible for bone loss in mice during spaceflight. Results showed significant femur bone loss in the space-exposed mice, whereas the spine remained unaffected, indicating that microgravity, not radiation, was the primary factor.
Additionally, the research discovered that spaceflight expedited endochondral ossification in the femur, a process where cartilage turns into bone.
Remarkably, mice housed in a specially enriched ISS habitat maintained or gained bone mass, while those in standard conditions lost bone.
The findings indicate that microgravity-induced unloading of weight-bearing bones is the chief cause of bone loss in space, contrasting with the muscle-focused impact on the spine.
Consequently, the astronauts’ bones might become more brittle and susceptible to fractures.
Dr. Tess Morris-Paterson, founder and managing director of Astro Perform, shared insights about the alarming rate of bone density loss in space.
“For the first two weeks on the ISS, our bones deteriorate in the same way they would if we stayed home and laid in bed all day for two weeks,” Dr. Tess explained.
She further elaborated, “The spine and pelvis decrease more than other parts of the body, but the trochanter—a small rounded point on the femur near its joint with the hip bone—is the worst affected, decreasing 1.56 percent per month.”