Astronauts install space junk protection on space station

Chinese astronauts have installed protection against space junk aboard the country's Tiangong space station.

Last month, a tiny piece of debris travelling at high speed cracked the window of the Shenzhou-20 spacecraft's return capsule.

It occurred right before the craft was set to leave Tiangong to carry three astronauts back to Earth.

But what is space junk and why is it such a problem? Keep reading to find out.

On November 5, the Shenzhou-20 spacecraft was meant to bring a group of astronauts back to Earth, after they finished a six-month stay aboard China's space station Tiangong.

However, the crew discovered a crack in the window of the vessel's return capsule right before take off, meaning the return mission had to be delayed.

The crew was forced to return to Earth in a different spaceship a week later.

In order to prevent a repeat of last month's incident, two astronauts went on a spacewalk, in order to install 'debris protection' using Tiangong's robotic arm, according to a statement from the China Manned Space Engineering Office.

The astronauts also inspected and photographed the damaged window of the Shenzhou-20 spacecraft, which is still docked at Tiangong.

It is waiting to be sent uncrewed back to Earth, after which experts will further examine the craft.

Space junk is also sometimes called space debris.

It could be bits of an old rocket that have failed or aren't in use any more, a broken satellite or even a screwdriver dropped by an astronaut!

As we send more things into space, lots of bits and pieces have been left behind.

When space junk is left in space it often just travels in orbit around the Earth.

The problem is that the junk that orbits the Earth is super fast - reaching speeds of up to 18,000mph (29,000km/h).

At these speeds even tiny pieces of debris can be a huge risk to astronauts living and working on the International Space Station (ISS), or travelling on spacecraft.

Space junk can cause problems for functioning space equipment too, it could even crash into satellites that are used for things like maps, mobile phones and the internet.

Any collision with space junk could cause disruptions to technology here on Earth.

However, the danger to us living on Earth's surface is minimal because most space junk burns up in the atmosphere and doesn't reach land.

Companies and spaces agencies are also looking at ways to clear up the litter left behind.

They include devices that can catch satellites and pull them back down to burn up in the atmosphere, lasers to knock objects out of orbit and big magnets or claws that can grab the pieces of junk as they fly past.