About Astronauts
Astronauts and cosmonauts are trained space travelers who operate spacecraft, conduct experiments, repair equipment, perform spacewalks, and live in microgravity. Their work combines science, engineering, teamwork, physical fitness, and years of specialized training.
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Astronaut Training
Space crews train for years before a mission.
Learn MoreLaunch and Reentry
Astronauts experience intense acceleration during launch and return.
Learn MoreLiving in Microgravity
Orbiting crews experience continuous free fall.
Learn MoreSpacewalks
Working outside a spacecraft is called extravehicular activity, or EVA.
Learn MoreStaying Healthy
The human body changes in microgravity.
Learn MoreScience in Orbit
Astronauts perform experiments that use the unusual conditions of space.
Learn MoreHuman Spaceflight History
Human spaceflight began in 1961 and quickly expanded.
Learn MoreFuture Crews
Future astronauts may spend longer periods farther from Earth.
Learn MoreAstronaut Training
Training can include spacecraft systems, emergency procedures, robotics, science experiments, physical conditioning, underwater practice for spacewalks, aircraft operations, and teamwork. International crews may also study additional languages.
Launch and Reentry
Rockets must accelerate spacecraft to orbital speed, which is much faster than ordinary aircraft. Crews wear specialized suits and follow detailed procedures during launch. Returning spacecraft must safely slow down while passing through Earth's atmosphere.
Living in Microgravity
Objects and people appear weightless because the spacecraft and everything inside it are falling around Earth together. Astronauts learn to sleep, eat, work, and move differently. Loose objects must be secured so they do not float away.
Spacewalks
A spacesuit acts like a small spacecraft, providing oxygen, pressure, temperature control, communications, and protection. Spacewalkers use tethers and carefully planned procedures while repairing equipment or installing new hardware.
Staying Healthy
Without normal gravity, muscles and bones can weaken. Astronauts exercise for hours each day on long missions. Scientists also study fluid shifts, sleep, balance, vision, radiation exposure, and how the body adapts after returning to Earth.
Science in Orbit
Research can investigate biology, materials, fluids, combustion, medicine, Earth observation, and technology. Microgravity lets scientists study processes without normal buoyancy and sedimentation effects.
Human Spaceflight History
Yuri Gagarin became the first person in space in April 1961. Humans later orbited Earth, walked on the Moon, flew reusable Space Shuttles, and built long-duration space stations. International crews now regularly live aboard the International Space Station.
Future Crews
Programs studying the Moon and Mars are helping engineers learn how crews could travel beyond low Earth orbit. Long missions require reliable life support, radiation protection, medical planning, food, power, communications, and ways to maintain mental and physical health.