German-built robots are to be sent into Earth's orbit to repair 'dead satellites' or push them into outer space

Robots that rescue failing satellites and push "dead" ones into outer space should be ready in four years, it has emerged. Experts described the development by German scientists as a crucial step in preventing a disaster in the Earth's crowded orbit.

Last year it was reported that critical levels of debris circling the Earth were threatening astronauts' lives and the future of the multibillion-pound satellite communications industry. But senior figures at the German Aerospace Centre (DLR) told the Observer they have been given the go-ahead to tackle a crisis that will come to a head in the next five to 10 years as more orbiting objects run out of fuel.

Their robots will dock with failing satellites to carry out repairs or push them into "graveyard orbits", freeing vital space in geostationary orbit. This is the narrow band 22,000 miles above the Earth in which orbiting objects appear fixed at the same point. More than 200 dead satellites litter this orbit. Within 10 years that number could increase fivefold, the International Association for the Advancement of Space Safety has warned.

Klaus Landzettel, head of space robotics at DLR, said engineering advances, including the development of machines that can withstand temperatures ranging from -170C (-274F) to 200C (392F), meant that the German robots will be "ready to be used on any satellite, whether it's designed to be docked or not".

In 2007, the US Orbital Express project succeeded in refuelling an orbiting satellite. However, that satellite had been specifically designed to dock with the device.