Astronauts can only survive in space wearing special suits. A rucksack supplies them with air to breathe, and removes exhaled carbon dioxide. Our viewer's question comes from Manuel V. E. from Mexico.
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00:00How is it possible for astronauts to do spacewalks?
00:08Working outside a station or vehicle in space is both difficult and dangerous.
00:13It's extremely cold where the ISS orbits, and there's no air.
00:18Human beings would perish after just 30 seconds out there.
00:22Astronauts can only survive in space wearing special suits,
00:26which are effectively like small spaceships.
00:29A rucksack supplies them with air to breathe and also removes exhaled carbon dioxide.
00:35The suits have several layers.
00:37They need to be gas-tight and withstand excess pressure.
00:41The outer layer is made of fire-retardant Kevlar coated with aluminium.
00:46The suits protect against the vacuum and the cold,
00:49as well as micrometeorites and solar radiation.
00:53Special underwear with tubes through which cool water flows
00:57prevents the astronauts from overheating during their strenuous work.
01:02Astronauts train for space missions in special swimming pools.
01:06Like divers, their more than 100 kilo-heavy suits are fitted with weights,
01:11which allow them to float, corresponding to the conditions in space.
01:18The International Space Station is a weightless environment.
01:22This is because it orbits the Earth so fast that centrifugal force and gravity balance each other out.
01:29It travels 7 kilometres per second.
01:36The astronauts are moving at the same speed, but they don't notice it.
01:40Physically speaking, outside the station, they're in their own orbit.
01:45Even a tiny push or movement can alter this orbit and cause them to drift away,
01:51like the objects that astronauts have already lost.
02:01They wouldn't be able to return on their own.
02:04That's why all astronauts are tethered to their spacecraft at all times.
02:12In 1984, NASA tested special jet backpacks.
02:16These were developed for missions where astronauts had to move far away from their spaceship.
02:20For example, to capture satellites.
02:26In an emergency, astronauts can ignite the thrusters to stabilise their position and then return to the ship.
02:39During extravehicular activities on the ISS, astronauts are secured with two tethers.
02:46These lines are attached to poles and handles, which the astronauts use to move around.
02:51When they change position, at least one tether must always be attached.
02:58For long distances, the astronauts also hover on the robotic arm to the deployment site.
03:04Special platforms for their feet hold them securely in place.