NASA astronaut Scott Kelly returned to the Earth after a one-year stint on the International Space Station and he’s 2 inches taller now! This temporary growth in height is a normal thing, as without the full strength of gravity pressing down on gel-filled discs between the vertebrae, they expand and lengthen the spine.

But that is not all NASA is interested in, as Scott was selected in 2012 for a year-long mission, to study the effects of long-term spaceflight on the human body. The fact that Scott has an identical twin brother, Mark (who is also an astronaut); helped the researchers more.


The earthbound twin was used as a sort of “control” for experiments being run on his orbiting brother. Even identical twins aren’t alike enough that NASA can pin every difference between them on the effects of spaceflight, but finding changes that occurred in one man and not the other over the course of a year might give them some important clues.

There are 10 official experiments running as part of the twin study, selected from a pool of research proposals submitted by institutions across the country: Six projects look at the way cellular behavior may change due to low gravity, high levels of radiation exposure, and other space-centric environmental factors. These studies will look at things such as how aging, gene expression, and immune system function may have been affected.


About this, NASA Administrator Charles Bolden said, “Scott Kelly’s one-year mission aboard the International Space Station has helped to advance deep space exploration and America’s Journey to Mars. Scott has become the first American astronaut to spend a year in space, and in so doing, helped us take one giant leap toward putting boots on Mars.”

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