Hugh Pickens writes writes "MIT Technology Review reports that various ideas have been floated for removing space junk, most of them hugely expensive, but now James Mason at NASA Ames Research Center has come up with the much cheaper option of zapping individual pieces of junk with a ground-based laser, to slow them down so that they eventually de-orbit. Mason estimates that a test device to test the reversal of the Kessler syndrome could be put together for a million dollars, which would have to be shared by many spacefaring nations, to avoid the inevitable legal issues that using such a device would raise. "The scheme requires launching nothing into space — except photons (PDF) — and requires no on-orbit interaction — except photon pressure. It is thus less likely to create additional debris risk in comparison to most debris removal schemes" writes Mason. "Eventually the concept may lead to an operational international system for shielding satellites and large debris objects from a majority of collisions as well as providing high accuracy debris tracking data and propellant-less station keeping for smallsats.""