Experts want to use nets and harpoons to haul in space junk threatening the $100 billion worth of satellites currently in orbit round Earth.

What sounds like a cosmic fishing trip is part of a raft of proposals to come out of a global conference on space debris ending Thursday in Darmstadt, Germany.

Others ideas include kamikaze robots and even lasers that act like "Star Trek" tractor beams.

Heiner Klinkrad of the European Space Agency says thousands of tons of debris are already orbiting Earth.

He says 5-10 large objects need to be collected each year to prevent what is known as the Kessler Syndrome _ when a few major collisions trigger a cascade effect in which each crash vastly increases the amount of dangerous debris in orbit.