More than 750,000 pieces of dangerous debris are now orbiting Earth and threatening the future of spaceflight, the largest ever conference on space rubbish has heard.

The European Space Agency (ESA) appealed to satellite operators and space agencies to clear up their retired crafts, many of which could impact launches, and are in danger of hitting the International Space Station.

“Only about 60 per cent of the satellites that should be disposed of at the end of their missions under current guidelines are, in fact, properly managed,” Dr Holger Krag, head of ESA’s debris office told the European Conference on Space Debris in Germany.

“This means urgently developing the means for actively removing debris, targeting about 10 large defunct satellites from orbit each year, beginning as soon as possible – starting later will not be nearly as effective.”

Since 1957, more than 5250 launches have led to more than 23,000 tracked objects in orbit around Earth.

But only about 1200 are working satellites – the rest are debris and no longer serve any useful purpose.

Many derelict craft have exploded or broken up, generating an estimated 750,000 pieces larger than 1 cm and a staggering 166 million larger than 1 mm.