Astronauts lose bone in space

A few months in space can lead to decades of permanent bone loss, according to a study published in Scientific Reports.

Researchers followed a group of 17 astronauts — 14 men and three women with an average age of 47 — for a year after they returned from four to seven-month missions aboard the International Space Station. All the astronauts experienced significant bone loss — equivalent to about two decades of bone loss for an older adult on Earth. Scans taken a year back on Earth showed that only about half the damage had been reversed for most astronauts.

Weight-bearing bones thin and weaken during spaceflight, and bone rods can eventually disconnect, said Leigh Gabel, study researcher, and professor at the University of Calgary, in an interview with Reuters. While remaining bone connections can be strengthened again, the disconnected spots can’t be rebuilt.

Researchers found that astronauts who prioritized strength training, particularly deadlifts, were more likely to recover bone after their return to Earth.

A deeper understanding of the health effects of microgravity — and how to mitigate those effects — is crucial as humanity sets its eyes toward more ambitious space voyages. One 2020 study in the journal PLOS One indicated that a three-year round trip to Mars could put 33 percent of astronauts at risk for osteoporosis. Astronauts also experience higher solar radiation and fluid shifts that can impact their cardiovascular systems and vision.