Japanese Astronaut Has Grown Taller In Space In Just Three Weeks

Joel Kowsky/NASAGetty Images

Japanese astronaut Norishige Kanai has grown taller by three and a half inches in space in just over three weeks. He is surprised and worried now that he won’t fit into the seat of the Russian Soyuz upon returning to planet Earth in April.

Kanai, together with astronauts Scott Tingle and Anton Shkaplerov, arrived at the International Space Station on Dec. 17, 2017. Recently, he made a major announcement on social media that he had grown by as much as nine centimeters. He compared himself to a plant that grew in just three weeks, as noted by Gizmodo.

NASA stated that astronauts could typically grow by two inches in space. So, the three and a half inches is quite remarkable and a lot. However, Libby Jackson, a program manager at the U.K. Space Agency, said that it is possible, knowing that every human body is different.

Astronauts get taller in space because of lack of gravity that makes their vertebrae in their spines expand. The gravitational force compresses the spine, and without this, the fluid between the discs may oscillate as they expand impermanently.

The growth in height in space is temporary. Once the astronaut returns home to Earth, his height will go back to normal. However, the height difference must be considered particularly when knowing the measurements of the spacesuits, stations, and vehicles.


Likewise, J.D. Polk, NASA’s chief health and medical officer, said that humans on Earth could regularly grow and shrink each night. When a human lies down, his spine expands by almost half a centimeter. Then, it will shrink again upon standing or sitting position.

Meanwhile, NASA stated that the Russian Soyuz TMA descent module could fit astronauts with up to a height of 6 feet 3 inches (190 cm). Kanai is now 6 feet (182 cm). This means if he could grow more than another three inches, it could pose a problem.

Other concerns of astronauts while staying in space include vision problems and plaque buildup in arteries, among others. The fluids in space tend to fluctuate and generate in the skull affecting the optic nerve. Radiation from the sun and galactic cosmic rays may also affect the astronauts in space. These may boost the risk of cancers and other medical conditions, according to Washington Post.