See that? It might be a dust particle from an asteroid! Or it might be a flake of dried skin from a man in the Japan Aerospace Exploration Agency factory that built the Hayabusa probe. No one knows yet.
The problem is, the recently-returned asteroid probe's dust-capture mechanism failed, meaning any dust that got inside the Special Dust Chamber will have only got in there by accident when the probe hit near-Earth asteroid Itokawa.