Space travel can be incredibly exciting, but what does it do to our bodies over long periods of time? A groundbreaking study of twin astronauts, Scott and Mark Kelly, reveals some fascinating insights into how extended space missions impact health — and how the body adapts to the challenges of life beyond Earth.
In 2015, Scott Kelly spent 340 days aboard the International Space Station (ISS) while his twin brother, Mark, remained on Earth. The study compared their physical and mental changes to uncover how space travel affects everything from metabolism to gene expression.
One of the most surprising discoveries was the change in Scott’s telomeres, the protective caps on chromosomes. In space, Scott’s telomeres actually grew longer, but after returning to Earth, they shortened rapidly. This could signal potential long-term effects, though more research is needed.
Another key finding was spaceflight-associated eye problems, which affect about 40% of astronauts. Scott experienced changes in his vision that may be linked to fluid shifts in his body in the weightless environment. And while most changes, like gut bacteria and immune function, returned to normal within six months, Scott faced persistent challenges, including declines in mental abilities and possible risks for stroke.
Despite these concerns, the study revealed some encouraging news: vaccines, like the flu shot, still work effectively in space, showing that the immune system responds much like it does on Earth.
The NASA Twins Study is providing critical data for future space exploration, especially as NASA plans for missions to Mars. While there’s still much to learn, it’s clear that understanding how the human body adapts to space will be essential for ensuring the health and safety of astronauts on long-duration missions.
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What Really Happens to Your Body in Space?
Ever wondered what actually happens to the human body during long-term space travel? Turns out, the answer is both weird and amazing.
NASA’s Twins Study gave us a rare chance to find out. In 2015, astronaut Scott Kelly spent 340 days aboard the International Space Station, while his identical twin brother, Mark, stayed on Earth. Since they share the same DNA, scientists could directly compare how space affected Scott’s body — from his cells to his mind.
Here’s what they found:
His DNA changed — sort of. Scott’s telomeres (the protective caps on chromosomes) actually got longer in space, which shocked scientists. But once he returned to Earth, they quickly shortened again.
His vision changed. Around 40% of astronauts develop vision problems in space, likely due to fluid shifts caused by microgravity.
His immune system still worked fine. Surprisingly, vaccines like the flu shot were still effective in space — good news for future missions!
His body adapted — but not perfectly. Some things, like gut bacteria and metabolism, returned to normal within months, but other effects (like slower mental performance and stroke risk) lingered longer.
This research is huge for the future of space travel. As NASA plans missions to Mars — which could take years — understanding how space affects the human body is more important than ever.
The takeaway? Space may look peaceful, but it pushes the human body to its limits — and yet, our ability to adapt is nothing short of extraordinary