Astronauts suffer ‘significant’ bone loss during space missions – raising concerns about future trips to Mars | world news
A scientist-led study of astronauts has revealed the devastating effects of space travel on the human skeleton.
The research showed that astronauts experienced “significant” bone loss during six-month spaceflights – the equivalent of about two decades on Earth.
Only about half of the bone lost was recovered a year after returning – raising concerns about future missions to Mars and the Moon.
Longer space missions resulted in increased bone loss and a reduced likelihood of healing.
Bone loss occurs due to a lack of gravity in space where normally load-bearing bones are weightless on Earth.
The study was conducted on 17 astronauts – 14 men and three women, with an average age of 47 – who flew on board International Space Station (ISS) in the last seven years.
The crew came from the US space agency NASAthe Canadian and European Space Agencies and the Japanese Aerospace Exploration Agency.
After returning to Earth, they worked for a year with a research team led by Professor Leigh Gabel of the University of Calgary.
Nine crew members experienced a permanent loss of bone mineral density after spending between four and seven months on space missions.
“Astronauts suffered significant bone loss during six-month spaceflights – a loss we would expect in older adults over two decades on Earth, and they only recovered about half of that loss after a year back on Earth,” Professor Gabel said the research, published in the journal Scientific Reports.
“We know that astronauts lose bones during long-term space flights.
“What’s new about this study is that we followed astronauts for a year after their spaceflight to understand if and how bones recover.”
Space agencies need to improve countermeasures like exercise and diet to prevent bone loss, Professor Gabel warned.
The study found that in-flight exercise, including resistance training on the ISS, proved crucial to preventing bone and muscle wasting.
Astronauts who deadlifted more weights compared to their usual training routine on Earth were more likely to recover after a mission.
The astronauts lost an average of 2.1% reduced density in the lower leg bone, tibia and 1.3% reduced bone strength.
‘During space flight, fine bone structures become thinner and eventually some of the bone rods separate,’ Professor Gabel said.
“Once the astronaut returns to Earth, the remaining bone connections can thicken and strengthen, but those that were severed in space cannot be rebuilt, so the astronaut’s overall bone structure changes permanently.”
The research also found that the cardiovascular system is also affected by space travel.
“Without gravity pulling blood to our feet, astronauts experience a fluid shift that causes more blood to pool in the upper body,” Professor Gabel said. “This can affect the cardiovascular system and vision.”
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Radiation is also a problem, as astronauts are exposed to more sunlight and an increased risk of cancer the farther they travel from Earth.
Professor Gabel added: “There is still a lot we don’t know about how microgravity affects human health, particularly in space missions lasting longer than six months, and about the long-term health consequences.
“We’re really hoping that bone loss will eventually plateau on longer missions, that people will stop losing bones, but we don’t know.”