Reaching New Heights: The Curious Case of Height Increase in Space

Ever wished you could be a bit taller? As an adult with closed growth plates, the only earthly option would be the surgical route, which involves quite literally breaking bones—a painful process that most would likely avoid if they could.

For those who feel a bit vertically challenged, there is another way—one that’s quite literally out of this world.

National Aeronautics and Space administration (NASA) scientists say that in space, astronauts can grow up to about 3% taller when they spend enough time living in microgravity. This means a person who stands 6 feet (1.8 meters) could gain up to 2 inches (5 centimeters) while in orbit.

To understand this, consider the analogy used in a National Space Centre video: imagine a vertical stack of sponges arranged together, representing the human spine. On Earth, gravity compresses our spines, but in the microgravity of the International Space Station (ISS), where astronauts are in constant free-fall around Earth, their spines can expand, making them taller—just like how sponges behave under pressure versus without it.

For instance, NASA astronaut Kate Rubins spent 115 days on the ISS in 2016. During her mission, she grew from 171 cm on Earth to 174.4 cm in space—a 3.4 cm or roughly 2% height increase!

Another interesting aspect of space exploration involves NASA astronauts (Ret.) Scott Kelly and Mark Kelly. Among many intriguing findings from the ‘Twins Study,’ one notable observation was that Scott Kelly grew almost 2 full inches taller than his identical twin brother Mark after living for nearly a year (340 days) aboard the International Space Station. This study took place during the historical One-Year Mission, which began in March 2015 and ended in March 2016.

The landmark Twins Study helped scientists better understand the impacts of spaceflight on the human body by studying identical twins. Scott Kelly spent one year in low-Earth orbit aboard the ISS, while Mark Kelly remained on Earth. The genetic similarity of the Kelly twins provided scientists with a reduced number of variables and an ideal control group, both crucial for scientific investigation.

However, a disclaimer: sorry to disappoint you, but this height change doesn’t last forever. Once astronauts return to Earth, under the influence of Earth’s gravitational force, they revert back to their original height.