Why does astronaut need to carry oxygen?

Humans & other animals use oxygen to power the cells of their body. Without oxygen, the cells of the body quickly lose energy and begin to malfunction.

To prevent this, astronauts bring a lot of oxygen with them into space, so their bodies & brains can continue to function properly.

You can do a little test yourself to see how important oxygen is:

1- exhale

2- start stopwatch

3- don't inhale for as long as possible

4- when you do inhale again, stop the timer.

How long did you go? Usually you'll feel the beginnings of oxygen starvation within 10 seconds. There's also a build up of carbon dioxide (a kind of burning sensation in the lungs).

Imagine that happening up in space and having no oxygen with you! It would not be very fun, and unconsciousness would occur within a minute or two. After that, well, cells would begin to die. When enough cells die, then permanent damage is done to a person's brain & heart--even if they get oxygen, the damage cannot be undone.

The astronaut will die if the lack of oxygen persists, so they make sure that they have more than enough oxygen with them before they go into space.