Stepping outside a spacecraft means carrying your own atmosphere. Extravehicular activity, usually called a spacewalk, covers any work an astronaut performs outside a pressurized vehicle. Construction, repairs, and science all happen in this environment.

The suit is a personal spacecraft. It supplies oxygen, regulates temperature, removes carbon dioxide, and shields against radiation and micrometeoroids. Astronauts train for years in neutral buoyancy pools that simulate weightlessness.

What spacewalks accomplish

• Assembling and servicing space station modules
• Repairing instruments and solar arrays
• Installing experiments outside the vehicle
• Testing new equipment and procedures

Every EVA is planned minute by minute. Consumables run out, astronauts tire, and rescue options are limited. Controllers on the ground monitor every step and can call an early return if anything goes wrong.