Some of you may have heard of the study just published by the NAS of the prospects of dealing with space junk - follow http://www.scientificamerican.com/article.cfm?id=orbital-debris-space-fence for the story and links. Most of the hazardous debris consists of extremely small particles. Further, due to the orbital advantage that arises from launches in an easterly direction, most of the debris is orbiting in this direction, albeit to some extent in inclined orbits. The problem with capturing the debris by mechanical means is that because of the high velocity, a collision of the particles with any capturing device is liable to result in disintegration of the particle, thereby increasing the number of particles and making the situation worse. I'd like to invite comments on the following idea. I propose launching clouds of gas into a retrograde orbit, in the opposite direction to the debris. Debris particles that enter the cloud undergo drag braking. The effect depends on the particle's cross section and its mass, meaning that the braking effect on smaller particles is greater than on larger particles, and the effect on objects as massive as satellites would be negligible. The braking effect causes the debris to descend into a lower orbit and finally into the atmosphere. The effect on satellites could be mitigated further by choosing orbital radius and inclination to avoid satellites. The choice of medium to use as a gas would need to be defined. For practical reasons, it could be launched as a vaporizing liquid, or it could be a sublimating solid. It should remain gaseous under orbital conditions, meaning zero pressure and an average 255K temperature. The cloud needs to be tenuous enough that satellites to not undergo excessive heating. The molecular weight should be such that it should not disperse to quickly, but equally it should disperse within a reasonable time scale.