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Researchers want to build a space station to recycle junk in Earth’s orbit

Aug 4, 2019

There are about 22,000 large objects orbiting the Earth, including working and broken satellites and bits of old rocket from past space expeditions.

If you include all the equipment dropped by astronauts while floating in space and the debris from colliding satellites down to around 1cm in size, there are about one million bits of space junk in Earth’s orbit.

These numbers are likely to be underestimates. With more satellites and rockets launching each year, collisions with space junk are becoming more likely. Losing a satellite could mean your TV reception is poor or the weather forecast is a bit less reliable. But it could also mean aeroplanes can’t navigate properly and people aren’t made aware of a tornado that’s bearing down towards them.

A long-term solution is needed to clean up space. The Gateway Earth Development Group is a collection of academics from universities around the world who propose turning this potential catastrophe into a resource. By 2050, Gateway Earth – a fully operational space station with a facility to recycle old satellites and other junk – could be up and running.

Earth’s orbits

There are two main orbits that satellites exist in. Low Earth Orbit (LEO) is about 200 km to 1,000 km above the Earth and is where the International Space Station orbits the planet every 90 minutes, along with thousands of other satellites. At 36,000 km, the forces acting on satellites cause them to stay in the same place within their orbit. This is called Geostationary Earth Orbit (GEO). Satellites here are stationary above a single point on Earth, making them useful for weather forecasting and communications.

LEO is very crowded, and there is a risk of collisions here which could create a shower of debris so wide it collides with other satellites, creating more and more debris in a chain reaction. Eventually the entire orbit could become so full of debris it’s unusable. A lot of debris already litters LEO, but technology is being developed and tested to remove it. The situation is more tricky for GEO, though.

In GEO, when a satellite comes towards the end of its life, the owners will attempt to put it in a higher “graveyard” orbit where it’s left to drift about 300 km to 400 km away from an internationally agreed protection zone. But only about 80% of all satellites that reach the end of their life in GEO actually make it to the graveyard orbit. The other 20% need dealing with as a matter of urgency – and that’s where a recycling facility in space could help.

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