John von Neumann's self-replicating machine — Critical components required

This paper introduces the concept of a physical self-replicating machine for deployment on the Moon utilizing raw material available on the Moon. A detailed but selective review is given in order to highlight clearly the novel aspects of the concept presented. In particular, it is hypothesized that if critical components - electric motors and vacuum tubes - can be 3D printed from the limited repertoire of lunar materials, 3D printing constitutes an effective universal construction mechanism. This follows from the observation that mechatronic components are the core constituent parts of all robotic mechanisms and that the robot is the key to von Neumann's universal constructor. Steps toward 3D printing of electric motors in particular and strategies toward the same regarding electronics is presented.