New Scientist: Boeing has filed a patent for a system for removing Earth-orbiting space debris. Ranging from screws to broken satellites, space debris poses an ever-increasing threat to rockets, satellites, and even the International Space Station. Many methods have been proposed to reduce the volume of debris, but Boeing’s is one of the first that doesn’t potentially add to the problem. The plan calls for launching a rocket to just inside the 100-km boundary of space and then vaporizing 10 tons of an inert gas such as xenon or krypton. Sprayed up to 600 km in altitude, the gas, by its density, would exert a small but significant drag on the orbiting debris. A reduction in orbital velocity of just 0.2 km/s would cause the material to lose altitude and enter the atmosphere, where it would burn up.