Space Time
A Year in Space Changed an Astronaut’s Genes
A new study of astronaut twins — one who spent a record time in orbit, the other who stayed on Earth — offers a clearer understanding of how space travel affects the human body
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In 2015, NASA astronaut Scott Kelly journeyed to the International Space Station (ISS), where he spent a year orbiting Earth. It was the longest single stretch of time any American had spent in space and gave scientists an opportunity to study how the body changes while in orbit. Even better, Scott Kelly has a twin brother, Mark Kelly, also an astronaut, who served as a scientific control on Earth, allowing researchers to precisely compare the two.
This was the most complex and in-depth study of human spaceflight to date. The average time any astronaut spends on the ISS typically maxes out at six months. In the months leading up to Scott Kelly’s yearlong flight, NASA scientists collected urine, fecal, and blood samples from both brothers. Scott also collected a cache of samples during his year in space. Once he returned, the medical analysis continued.
After years of analysis, more data is emerging to illuminate how Scott’s year in space changed his body. A new paper published in the journal Science reveals changes that occurred in Scott’s genes. Some were expected, while others were a surprise.
“The Twins Study is the most comprehensive view of the response of the human body to spaceflight ever conducted,” said Susan Bailey, one of the study’s authors and director of cancer biology at Colorado State University, over email.
We take for granted how safe it is to live on Earth. The planet’s atmosphere provides us with breathable air. Its magnetic field acts as a shield against the bulk of solar radiation and galactic cosmic rays. When a person leaves Earth’s protective boundary, almost all bets are off.
The microgravity environment of space allows our organs to shift around, which affects the way our heart muscles pump blood through the body. As a result, heart disease is a major risk for astronauts, and many are diagnosed with cardiovascular disease after returning to Earth. Other space…
