Extra-vehicular activity

In space flight[?], extra-vehicular activity (EVA) work done by an astronaut outside of the spacecraft. In the early days of space flight it was called 'space walk'. The first EVA was carried out by Soviet cosmonaut Aleksei Leonov on March 18, 1965 from the Voskhod 2 spacecraft.

An EVA is dangerous business for a number of different reasons. The primary one is collision with debris. Orbital velocity at 300km above the Earth (typical for a Space Shuttle mission) is 7.7km/sec. This is 10 times the speed of a bullet, so the kinetic energy of a particle as small as a fleck of paint or a grain of sand is equal to that of a bullet with a mass that is 100 times as large! Every space mission creates more orbiting debris, so this problem will continue to become worse.

Scientists are developing tele-operated robots for outside construction work, to eliminate the need for EVAs.

See also MMU.

External link: http://spaceboy.nasda.go.jp/note/yujin/e/yuj101_eva_e

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Also name of mechas in Neon Genesis Evangelion.