To address the NASA need for innovative, advanced, high-precision micropropulsion technologies to increase the operational capabilities and reduce the cost of Earth Science under-10-kg spacecraft for long-life missions, Physical Optics Corporation (POC) proposes to develop a new Silicon Digital Propulsion (SIDIP) system. SIDIP will be inexpensive and power efficient, with minimal mass, and will deliver digitally controlled, high-precision attitude control and in-space maneuvering through micropulses of regulated duration and frequency. The SIDIP system is based on two key innovations: development of a novel, MEMS-based periodic structure of subminiature microthrusters; and unique implementation of the microelectromechanical systems (MEMS) technology that POC has developed for processing Si wafers for precise micromachining of the hundreds (or more) of subminiature field emission electric microthrusters on a 1 in. x 1 in. Si microthruster plate (MTP). SIDIP will remarkably increase the precision of in-space maneuvering, and improve attitude and orbit control. NASA Earth Science missions will benefit from SIDIP, especially for miniatusre satellites in a cluster or constellation. In Phase I POC will optimize the SIDIP system geometry, develop technology for micromachining silicon MTPs, and demonstrate technologies for fabricating pyrimids and oxidizing matrix channels. In Phase II POC will demonstrate an engineering prototype SIDIP.