What Happens to Your Body in Deep Space?

Imagine your body is a house built for gravity. In space, the house starts to change because there is no weight pulling everything down.

Your blood and water don't stay in your legs anymore. They float up into your chest and head. This makes you look puffy with a big face and skinny legs. It feels like you have a cold all the time because your nose gets stuffy from the extra fluid.

When you walk on Earth, gravity pulls on your muscles and bones. In space, they do not work as hard. They get lazy and shrink. This is called atrophy. Your bones become brittle like old chalk because they are losing calcium. If you stayed in space too long, it might be hard to stand up when you returned to Earth.

Your heart does not have to pump as hard to push blood against gravity. It becomes more round and efficient. However, this means your body thinks you have too much fluid because of the puffy face. It tries to get rid of it by making less urine at first, then dumping a lot when you come back down.

Astronauts exercise for two hours every day on special machines. This keeps their muscles strong and helps their bones remember their weight. Without these workouts, they would become weak and sick.