While doing my recent research on hypogravity and its effects on the human body, I’ve seen the term space adaptation syndrome come up a few times. I figured it would make a good Sciency Words post. Then I discovered, to my surprise, that I’d already done this one!
So today I’d like to present to you, apparently for the second time:
SPACE ADAPTATION SYNDROME
Yeah, we could just call it “space sickness,” but this is Sciency Words, so we have to call it “space adaptation syndrome.” Because NASA has a rule that all space related terms must be turned into acronyms, we can also call it “S.A.S.”
Most astronauts experience space adaptation syndrome at some point, usually during training or during their first few days in space. Relapses are also known to happen. As you can imagine, NASA really wants to figure out what causes S.A.S. and how to prevent it. This is one of the reasons they recently left an astronaut in space for almost a full year.

At present, S.A.S. seems to be similar to motion sickness. It is also sort of the exact opposite of motion sickness. Think of it this way:
- Motion sickness: your inner ear senses motion, but your eyes do not (because you’re playing with your phone in a moving car, for example). In this case, your eyes are feeding your brain false information.
- Space adaptation syndrome: your eyes see that you’re moving (or not moving), but in the absence of gravity, your inner ear hasn’t got a clue what’s going on. So in this case, your eyes are trustworthy; it’s your inner ear feeding false information to your brain.
The good news is that we humans can adapt. Our brains learn to rely less on our inner ears, allowing the business of human space exploration to continue.
The bad news is that once we humans adapt to space, returning to Earth becomes a problem. I’m not talking about bone loss or muscle atrophy. I’m talking about balance. All of a sudden, your inner ear is working again, and your brain has to relearn how to do this balancing and walking stuff.
There is also a concern—and I’m not sure how seriously to take this concern—that the human body might adapt too well to space. You might spend so much time up there, becoming so acclimated to zero-G, that your brain and inner ear will never function properly together again. You’ll never walk again. You’ll never be able to come home. You’ll be stuck in space for the rest of your life.
That would suck.
Or maybe it wouldn’t. To be honest, if I ever get to go to space, I probably won’t want to come back anyway.
P.S.: Here’s a bonus Sciency Word: lead-head. Lead-head is what astronauts call immunity from space adaptation syndrome.
“Lead heads.” That’s a story that almost writes itself!
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Definitely a good term to have in a Sci-Fi writer’s vocabulary.
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Yeah, I mean, it’s a title, or it’s a story about them, or a nickname, so many possible uses.
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I’ll probably use it as space marine slang or something. We’ll see.
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Yeah, that’s exactly what I was picturing. I pictured starship troopers or aliens.
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