Although this is a small sample, it suggests that man-made dust particles predominate over naturally occurring ones.

ECONOMIST: Orbital debris

At the same time, the experiment's clever design makes it possible to distinguish between man-made and naturally occurring dust particles, and so determine their relative proportions.

ECONOMIST: Orbital debris

Whether a speck of dust is man-made or natural can be worked out from its trajectory.

ECONOMIST: Orbital debris

So most dust now in orbit around earth can be assumed to be man-made.

ECONOMIST: Orbital debris