Do Astronauts Get Taller In Space? Uncover the Truth

Elmira | 05 - 04 - 2021

Astronauts in space can grow up to 2 inches when they live in microgravity. It means if an astronaut’s height is 6 foot then he could be taller 2 inches more (5 centimeters) while in orbit. But when astronauts’ hit by regular gravity, their bodies will shrink down and return to normal.

Astronaut Height Increase

Is it true that Astronauts get taller in space? It occurs not because of optical illusion; it happens due to micro activity effects in human bodies. Astronauts look 2 inches taller in space due to the disks of the spinal column. On Earth, the disks are slightly compressed because of gravity. But in space compression won’t be present to cause the disks to expand. As a result, the spine lengthens and the astronauts look taller. The spine elongates up to 3 percent while astronauts travel in space.

Astronaut Scott Kelly Is 2 Inches Taller

In Space, Gravity No Longer Pulls in a Direction to Make Astronauts Shorter.
  • A. True
  • B. False

After living for almost a year on the International Space Station, NASA astronaut Scott Kelly grew 2 inches taller than his twin brother Mark. He proudly stated that after spending time on the International Space Station for three weeks; he grew three and a half inches.

Living in Space can make astronauts grow taller but it also causes back problems. These include

  • Brittle bones
  • Weak muscles
  • Smaller heart
  • Puffy face and legs
  • Can experience problems such as focusing on their gaze and standing up
  • Increase cancer risk

Two Theories Why Spine Gets Longer

NASA discovered that the height of astronauts increases around 3 percent after 3 to 4 days of weightlessness in space. As soon as they return to Earth, gravity pulls on them again. Hence astronauts will typically return to their usual heights in a short amount of time. The height increase in the spinal column also causes changes in other body measurements such as eye height, sitting height, standing height and more.

Dr. Sudhakar Rajulu, a researcher at Johnson Space Center’s Habitability and Environmental Factors Office came up with two theories that explain why the spine gets longer.

The first theory says it is an elongation that only occurs to the spine. It doesn’t cause major impacts on the other parts of the body such as legs or arms because these bones can’t be compressed like the discs in the spine. The spine’s natural curve is straightened in space. Therefore, the spine is free to relax without any normal force of gravity pushing down on it, like on Earth.

The second theory is about spinal elongation. It talks about the discs between every vertebra pressed together in normal gravity. This compression occurs due to the vertebra which pulls the spine downward. When gravity is reduced in space, the discs can hold more spinal fluid. This makes spines larger and also provides more spaces between every vertebra.

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