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2 EVA hazards
An EVA is dangerous for a number of different reasons. The primary one is collision with space debris. Orbital velocity at 300 km above the Earth (typical for a Space Shuttle mission) is 7.7 km/s. This is 10 times the speed of a bullet, so the kinetic energy of a small particle (e.g. 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.
Another reason for danger is that external environments in space are harder to simulate before the mission and that space walks are avoided for routine tasks because of their danger. As a result the EVAs are often planned late in the project development when problems are discovered, or sometimes even during an operational mission. The exceptional danger involved in EVAs inevitably leads to emotional pressures on astronauts who, though selected for exceptional stability under pressure, are still human.
Scientists are developing tele-operated robots for outside construction work, to eliminate the need for EVAs.
3 See also
4 External link
