The document outlines the basic requirements to become an astronaut for major space agencies. Candidates must 1) be a citizen of countries like the USA, Russia, or China with active space programs; 2) fall within certain age ranges, typically between 27-37 for ESA and 26-46 for NASA; 3) meet height requirements of between 5'0"-6'3"; and 4) pass a physical examination with standards such as 20/20 vision and low blood pressure. Additional requirements include speaking English and knowing how to swim well.