Do Astronauts Get Taller In Space?

How much taller do astronauts get in Space?

In space, the human body can experience a growth of up to three percent, which equates to around two inches for an astronaut who is six feet tall.

During a 2016 Q&A session with schoolchildren while still on his spaceflight, UK astronaut Tim Peake informed the students that he had noticed an increase in his height since launch. He stated, "I'm not sure exactly how tall I am, but when I sat in my Soyuz seat the other day, I realised that I was taller than when I launched... So, I have probably grown by about two or three centimetres."

As a result of this growth, spacecraft seats and spacesuits for astronauts need to be carefully constructed.

In 2018, Japanese astronaut Norishige Kanai claimed that he had grown by three and a half inches within his first three weeks in space. However, it was soon discovered that he had made a measurement error, and thankfully, astronauts do not grow that rapidly or by such a significant amount.

Why do astronauts get taller in space?

The human spine is made up of discs that are separated by cartilage - a strong and flexible tissue found in the body. On Earth, gravity causes compression of the spine. However, in the microgravity environment of space, the cushioning cartilage doesn't experience the same compression force, which results in elongation of the spine.

This effect is temporary, as astronauts return to their pre-flight height within a few months of coming back to Earth and experiencing its gravity once more, which compresses the spine again. However, this elongation comes with side effects, including back pain, which is a common complaint amongst astronauts. Around 50% of astronauts experience this, and NASA has conducted further studies on this issue.



Interestingly, a similar effect occurs on a daily basis when we sleep at night. Lying horizontally, the spine doesn't experience the same vertical pull of gravity as when we are upright during the day. As a result, we may find ourselves around one centimetre taller in the morning than we were the night before.

Research on height and space

NASA's Twins Study, which involved astronaut Scott Kelly spending 340 days in space while his twin Mark Kelly stayed on Earth, revealed a small-scale growth in other parts of the body.

Telomeres, which act as protective caps on the ends of our chromosomes to safeguard our DNA from damage, have been found to lengthen while in space. While they naturally degrade with age, research suggests that longer telomeres may be associated with fewer age-related problems.



However, just like the spine, telomeres return to their pre-flight lengths once astronauts return to Earth. It is believed that the temporary lengthening may be due to the strict exercise regime and controlled diet followed by astronauts while in space.

Not just height impacted by space

Astronauts may appear to have plumper or swollen faces when they are in space, which is more noticeable than other physical changes.

This is because on Earth, gravity pulls bodily fluids downwards, making the heart work harder to pump blood upwards to the head and brain. However, in the microgravity environment of the ISS, fluids are no longer pulled downwards, and the heart has an easier job of sending blood to the head, resulting in fluid accumulation in the upper body and face.



Typically, after a few weeks in space, the swelling in the face subsides as the body's fluids balance out.