Harpoon-firing satellite designed to hunt space junk

Scientists say space debris orbiting earth must be cleaned urgently before the problem snowballs.
The satellite is designed to maneuver close its target, then fire a harpoon. Once tethered, the satellite drags its target out of orbit, allowing the object to fall through earth's atmosphere and burn up. The harpoon is equipped with a barbed tip and flange to stop it from penetrating too deeply into volatile objects, such as abandoned rocket stages, which might explode. When a tether is impractical, a harpoon equipped with a propulsion pack nudges the target back to earth.
The European Space Agency is also considering a satellite which fires a net at its target.