A study of bone loss in 17 astronauts who travelled on the International Space Station provides a complete understanding of the impact of space travel on the human body and the steps that can mitigate it.
The study collected new data on astronauts’ reduced bone density due to microgravity conditions in space and how much bone mineral density can be restored on Earth.
The study included 14 astronauts and three female astronauts, their average age was 47, and their time in space ranged from four to seven months, with an average of about five and a half months.
A year after their return to Earth, tests showed an average decrease of 2.1 percent in bone mineral density in the tibia and a decrease in bone strength of 1.3 percent in the astronauts. Nine of them had not recovered their bone mineral density after the space flight and had a permanent loss.
“We know that astronauts lose bones in long-duration spaceflights,” said Lee Gabel, a University of Calgary professor and exercise scientist and lead author of the study published last week in Scientific Reports. What is new about this study is that we followed the astronauts for one year after they travelled to space to understand whether and how the bones were healing.”
“The astronauts suffered significant bone loss during their six-month spaceflights, a process we would expect to see in older adults over twenty years on Earth, and they regained half of what they lost after one year on Earth,” Gabel added.
The problem occurs because bones that normally carry weight on Earth do not carry weight in space. Gabel said space agencies should boost countermeasures, namely exercise and nutrition regimens, to help prevent bone loss.
Space travel presents various challenges to the human body, which poses a major concern for space agencies as they plan new explorations.
For example, the US Aeronautics and Space Administration (NASA) aims to send astronauts to the Moon again, a mission planned for 2025 at the earliest. This could be a prelude to future missions to Mars by astronauts or a long-term stay on the Moon.
“Microgravity affects many systems in the body, including muscles and bones,” Gabel said.
She continued: “The heart and blood vessels also suffer from many changes. Without gravity pulling blood toward our feet, a fluid shift occurs that causes more blood to pool in the upper body of the astronauts. This can affect the cardiovascular system and vision.”
And she added, “Radiation is also a major health concern for astronauts because the further away from Earth, the greater their exposure to sunlight and the greater the risk of cancer.”
