When it comes to solving the growing space junk problem, solutions range from catching it in giant nets to blasting it from orbit with lasers--and these are DARPA’s and NASA’s best plans, respectively. By contrast, the Naval Research Laboratory has a scheme that seems much more feasible, though fraught with negative consequences: using a cloud of tungsten dust to create atmospheric drag at orbital altitudes, deorbiting the thousands of pieces of tiny space junk whirling about the heavens.
The idea is simple enough: at altitudes below about 560 miles, the drag of the atmosphere naturally decays orbits, causing smaller bits of debris to slowly lose their orbits over the course of a couple of decades. But above that limit small debris--the stuff smaller than 10 centimeters that is very hard to track--can stay up there for decades or even centuries, threatening to damage satellites and spacecraft.A researcher at the U.S. NRL suggests releasing a cloud of tungsten dust at about 680 miles up, creating a layer of particles that will completely shroud the planet. The particles themselves will be just 30 micrometers across, but because tungsten is nearly twice as dense as lead they will still add effective weight to any small debris they latch on to.