太空垃圾

Many of us ponder what lies in outer space. When we look up at the night sky, we see stars, the twinkle of a moving satellite and occasionally a distant planet. But one thing we don't see is the millions of pieces of junk filling up space. It's this debris that's causing problems for the existing technology that's up there and which we rely on.

The amount of space junk is increasing. Over the last few decades, satellites and rockets have been launched into space, littering the cosmos as they go. It's estimated there are now millions of discarded pieces of metal and other materials in orbit – everything from old rocket segments to accidentally dropped astronaut tools, and even flecks of paint. The fear is that if we don't start taking this litter out of the sky soon, it will become a significant threat to active satellites. Nobu Okada, Chief Executive of Astroscale – a company working on ways to clean up space junk – says hitting "even a small paint fleck… has enough power to blow up other satellites."

Several ideas are being looked at to capturethe debris floating around in space. In 2018, the RemoveDebris spacecraft carried out various experiments, including testing a net that could snare a satellite and firing a harpoon at a target in orbit to try to catch it.

This year the UK Space Agency is helping to fund new approaches to tracking satellites and debris in space. Jacob Geer from UKSA told the BBC: "Space surveillance and tracking is one of the key things we can do to keep safe those satellites we rely on now, and to make sure certain orbits don't become inaccessible for future generations because there's too much debris in them."

It's clear that a solution is needed so a celestial deep clean can take place. But looking to the future, like any litter problem, we need to look at ways of creating less – and that shouldn't be the stuff of science fiction.