When astronauts are in the International Space Station, they can breathe normally in their living areas. However, when they go on a spacewalk to work on the Space Station, to repair or replace parts, they must be in a spacesuit. Why must they have their own supply of oxygen within the spacesuit?

This is because of wide variety of temperature astronauts face during space walking. Temperature can be as cold as minus 250 degrees Fahrenheit and In sunlight, they can be as hot as 250 degrees. A spacesuit protects astronauts from those extreme temperatures. In space, there is no air to breath and no air pressure, spacesuits supplies them with oxygen to breath while they are in a vacuum of space.

Explanation:

There are so many ways a space suit helps an astronaut. The suits contain water to drink during spacewalks. They protect astronauts from being injured from impacts of small bits of space dust this space dust may not sound very dangerous, but when even a tiny object is moving many times faster than a bullet, it can cause injury. Spacesuits also protect astronauts from space radiation. The suits even have visors to protect astronauts' eyes from the bright sunlight in spacecraft.