Astronauts sacrifice a lot to explore the mysteries of deep space, and it is well known that a zero gravity environment leads to bone loss.
However, a new study shows that astronauts on space missions lasting more than three months may show signs of incomplete bone recovery even after a full year on Earth.
“The detrimental effects of spaceflight on skeletal tissue could be profound,” says the first line of a study published today in Scientific reports.
“We found that in most astronauts a year after spaceflight, the load-bearing bones only partially regenerate,” says Lee Gable, assistant professor of kinesiology and lead author of the study. statement.

The effect of weightlessness on an astronaut’s bones can be “deep” according to the study. The image above shows astronaut Tom Marshburn after he affixed the official NASA astronaut emblem to ESA (European Space Agency) astronaut Matthias Maurer after the Crew-3 Crew Dragon Endurance successfully docked with the International Space Station.
“This suggests that irreversible bone loss due to spaceflight is about the same as age-related bone loss on Earth in a decade.”
The study was launched in 2017 and involved 17 astronauts before and after spaceflight over a period of seven years to determine how bones do or don’t regenerate after longer spaceflights.
Researchers traveled to the Johnson Space Center in Houston, Texas, and scanned astronauts’ wrists and ankles before they took off into space.
A year after returning from a long space flight, most astronauts experienced incomplete recovery of bone density, strength, and thickness of the trabeculae in the supporting distal tibia.

The researchers found that incomplete restoration of bone density and strength was more pronounced in astronauts who flew on longer missions. The image above is of the International Space Station, photographed by members of the Expedition 56 crew.
When astronauts float in microgravity, their bones, which would have to carry weight on Earth, don’t have to carry any weight.
“Understanding what happens to astronauts and how they recover is incredibly rare. This allows us to look at the processes occurring in the body in such a short time. We would have to follow someone for decades on Earth to see the same bone loss,” explains Gable.
Incomplete recovery of bone density and strength was more pronounced in astronauts who flew on longer missions, whose post-spaceflight bone loss was significantly higher than in astronauts on shorter missions.
The researchers noted that all astronauts react differently to the physical effects of space travel.

All astronauts recover differently from weightlessness. The image above shows the deployment of science experiments by astronaut Edwin Aldrin Jr. photographed by astronaut Neil Armstrong during the Apollo 11 mission to the moon.
“We have seen astronauts having trouble walking due to weakness and loss of balance after returning from space flight, and others jovially cycling around the Johnson Space Center campus to meet us on a study visit,” says doctor. Stephen Body, director of the McCaig Institute for Bone and Joint Health and professor at Cumming School of Medicine, who started the study.
As space travel enters a new era where long-duration missions may become more common, the next study plans to explore the impact of even longer missions.”
Astronaut Robert Thirsk knows how strange returning to Earth can be: “Just as the body must adapt to spaceflight at the beginning of a mission, it must also adapt again to Earth’s gravitational field at the end,” says Thirsk, a former Calgary chancellor. .
“Fatigue, dizziness and imbalance became immediate problems for me upon my return. Bones and muscles take the longest to recover from spaceflight.
“But a day after landing, I felt like an earthling again.”
The research team included two members of the European Space Agency (ESA), Dr. J. Anna-Maria Liphardt and Martina Heer, and two from NASA, Dr. Scott Smith and Dr. Jean Sibonga.
The study was funded by the Canadian Space Agency and carried out in collaboration with ESA, NASA and astronauts from North America, Europe and Asia.