Any time an astronaut gets out of a vehicle（交通工具） while in space, it is called a spacewalk. The first person to go on a spacewalk was Alexei Leonov, a man from Russia. It lasted for 10 minutes on March 18, 1965. In China, Zhai Zhigang was the first person to step out of the spacecraft（宇宙飞船） and take a spacewalk during the Shenzhou VII manned spaceflight mission（任务）. If you are wondering the mysteries of spacewalks, come and have a look.
Why Do Astronauts Go on Spacewalks?
Astronauts go on spacewalks for many reasons. Spacewalks let astronauts work outside their spacecraft while still in space. Astronauts can do science experiments on a spacewalk. This lets scientists learn how being in space affects（影响） different things. Besides, spacewalks also let astronauts test new equipment（设备）. By going on spacewalks, astronauts can fix（安装） things instead of bringing them back to Earth to fix.
How Do Astronauts Go on Spacewalks?
When astronauts go on spacewalks, they wear spacesuits to keep themselves safe. Inside spacesuits, astronauts have the oxygen（氧气） they need to breathe. They have the water they need to drink. Astronauts put on their spacesuits several hours before a spacewalk. Once in their suits, astronauts breathe oxygen for a few hours. Breathing only oxygen gets rid of all the nitrogen（氮气） in an astronaut's body. If they didn't get rid of the nitrogen, the astronauts might get gas bubbles in their body while walking. When they are ready to get out of their spacecraft, they passed through an air lock with two doors. After a spacewalk, astronauts go back inside through the air lock with relaxing muscles and minds.
