How Damaging Is Space Travel to the Human Body?

An alarming new study has raised concerns about the feasibility of long-distance space travel, including future Mars missions.

Due to the effects of microgravity, as little as six months in space can result in the equivalent of two decades' worth of bone loss. Unfortunately, around half of the weakening of weight-bearing bones appears to be irreversible, meaning that half a year in space permanently adds a decade's worth of age-related bone loss to an astronaut's skeletal structure.

In a project conducted over seven years, researchers from the University of Calgary studied 17 astronauts who stayed on the International Space Station for missions lasting between four and seven months. Using a 3D scanning technique known as high-resolution peripheral quantitative computed tomography (HR-pQCT), the researchers scanned the astronauts' wrists, ankles, and shins both before and immediately after their missions to determine their bone density and bone mineral content. They followed up with scans six months and 12 months after the return to Earth.

Interestingly, after a year back on Earth, 16 of the 17 astronauts still had weakened tibia bones. This effect was especially noticeable in those who had spent more than six months in space. The non-weight-bearing radii (lower arm) bones showed very little deterioration.

Lost (bone density) in space: