How do astronauts carry out spacewalks?

DW (English)

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.

Transcript

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.

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