re: Probably wouldn't work
Well, here's Japan's idea of how to do that (against a rocky surface).
In yet another technological experiment, Hayabusa will carry a sample horn that will be brought into contact with the asteroid's surface. A small pyrotechnic charge will fire a projectile into the surface, ideally smashing part of it. The resulting impact fragments will be sucked through the funnel into a sample container. The sample container will then be hermetically sealed and prepared for return to Earth.