Astronauts Grow Taller In Space

One of the more peculiar physical changes an astronaut experiences is a temporary growth spurt in orbit. This phenomenon is entirely due to the spine. On Earth, gravity constantly compresses our vertebral column, squeezing the spongy, fluid-filled discs that act as cushions between each vertebra. In the microgravity environment of space, this compressive force vanishes. Freed from the constant downward pull, these discs absorb more fluid and expand, lengthening the spine and adding up to 3% to an astronaut's total height.

This spinal elongation was first systematically observed during long-duration missions like the Skylab program in the 1970s. While it may sound like a benefit, the process can be uncomfortable, often leading to back pain as the spine adjusts to its new length. The change is so significant that it must be factored into the design of spacesuits and spacecraft cabins to ensure a proper fit throughout a mission. Of course, this newfound height is fleeting. Upon returning to Earth, gravity quickly reasserts its dominance, and astronauts typically return to their original height within a few days or weeks as their spinal discs re-compress.