By combining new robot control systems with piezoelectric motors and micromechanics, we propose creating micromechanical systems which are small, cheap and completely autonomous. We have fabricated small - a few millimeters in diameter - piezoelectric motors using ferroelectric thin films and consisting of two pieces: a stator and a rotor. The stationary stator includes a piezoelectric film in which we induce bending in the form of a traveling wave. Anything which sits atop the stator is propelled by the wave. A small glass lens placed upon the stator becomes the spinning rotor. Using thin films of PZT on silicon nitride memebranes, various types of actuator structures have been fabricated.

Spur-of-the-moment planetary exploration missions are within our reach. Complex systems and complex missions usually take years of planning and force launches to become incredibly expensive. We argue here for cheap, fast missions using large numbers of mass produced simple autonomous robots that are small by today's standards, perhaps 1 to 2kg. We suggest that within a few years it will be possible, at modest cost, to invade a planet with millions of tiny robots.