This thesis details the development of the Miniaturized Electrostatic DUal top-hat Spherical Analyzer (MEDUSA) instrument, including calibration, simulation, and data processing software. MEDUSA combines two-species observations with state-of-the-art miniaturization to achieve a low-cost, compact instrument capable of making the measurements that will be required in the future. Calibration of the instrument was performed during November 1997 and July 1998. In order to better understand the characteristics of the instrument, it was also modeled in detail with a modified 2.5 dimensional raytracing code. The production processing software is designed to archive the data into the standard Instrument Data File Set (IDFS) format of the Southwest Data Display and Analysis System (SDDAS). MEDUSA has so far proven itself to be a reliable, low-cost instrument capable of making the scientific measurements required for a better understanding of the behavior of the near-Earth particle environment.