How do humans age in space?

by Jessika Toothman

Browse the article How do humans age in space?

How do humans age in space?

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A long trip in space might leave this astronaut feeling like his great-grandfather.

Because astronauts like the ones on the International Space Station (ISS) are moving so quickly, they're also aging a bit more slowly than the rest of us. Due to a principle of physics known as time dilation, after a six-month stint on the ISS, returning astronauts are just a tiny bit younger than the rest of us. But before you book a ticket that'll take you literally out of this world, understand this isn't exactly a fountain of youth we're talking about. Your six-month effort at age reduction will only garner you about 0.007 seconds of extra life, according to the calculations of one ISS astronaut [source: Lu].
But that's not really the issue we're talking about when we discuss how humans age in space. Let's start with a rundown of how the aging process typically proceeds on Earth. Until scientists muster up a way to make us all immortal, most of us will go through the process of aging. This typically involves metamorphoses like bones becoming brittle, blood vessels hardening, muscles wasting away, joints stiffening up, bowels turning irritable, bladders becoming unpredictable, teeth decaying, vision growing dim, skin wrinkling up, and so on.
While for most people, it takes decades to really start to feel the effects of the aging process, humans stationed in space experience some of them in fast-forward. They're often reversible once an astronaut returns home, although sometimes a few of the changes can be permanent.

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