An astronaut is someone who is trained to go into space. Astronauts have to go through a lot of testing and training to prove they can handle going into space. For example, they have to practice going into zero gravity by training in special machines. In a spaceship, the astronauts all have different jobs. The most important job is commander, who is leader of the mission. There is also a pilot and other astronauts who are trained in other areas like science and engineering. Astronauts must wear a spacesuit when they go into space. The spacesuit is specially designed to protect the astronauts from the extreme hot and cold temperatures in space. Most importantly, the spacesuit provides astronauts with oxygen. If an astronaut needs to leave the spaceship they attach tethers to their suit so they do not float away in zero gravity. There are even small rocket thrusters on the spacesuit to make getting around the rocket ship easier.