Introduction M ICROSPACECRAFT have increasingly attracted the interest of researchers in recent years. The research is motivated by the need to reduce in the cost of developing and launching spacecraft and to improve in the mission capability and redundancy using microspacecraft constellations. Although several laboratory and flight models of 1–10 kg class microspacecraft have been developed, most of them do not have propulsion systems.1−3 To enable future microspacecraft missions, such as formation flying, a small propulsion system suitable for microspacecraft, namely, a microthruster, is needed.4 One of the most important requirements in the microthruster is the capability to generate both lower range thrust and higher range thrust. For instance, microspacecraft require lower thrust for attitude controls and higher thrust for slew maneuvers. In the case of formation flying,4 microspacecraft need lower thrust for the constellation controls and higher thrust for the rearrangement of their formation patterns. In particular, formation flying inevitably requires propulsive capability, although attitude control is accomplished by passive systems such as momentum wheels and magnetic torqueres. To limit the weight and size of microspacecraft, it is essential to satisfy the requirement of lower and higher range thrusts with the same propulsion system. To our knowledge, there is as yet no single propulsion system that can supply such a wide range of thrust for the 1–10 kg class microspacecraft. A diode laser ablation microthruster and digital microthruster array seem to be promising candidates for the 1–10 kg class microspacecraft. The diode laser ablation microthruster5 uses laser beams to irradiate the surface of a polymer propellant, and the heated