For NASA to gain high-value science from SmallSat technology requires lightweight, miniaturized, precision impulse bit, fuel efficient propulsion systems that extend mission time and greatly enhance SmallSat utility. While a broad range of chemical and EP systems are under consideration for SmallSat thrusters, micro-fabricated electrospray (ESP) arrays have been clearly identified as an emerging technology for thruster attitude control as well as delta-v maneuvers, with scalability that also makes them attractive for applications on larger spacecraft. ESPET will accelerate the development of ESP systems that meet NASA requirements. ESPET will provide NASA with a tool for quick comparison of various fuels and thruster configurations. It will provide designers with estimates of thruster fuel and power efficiency, stability of output thrust, and potential for contamination effects. It will also enable them to develop accurate thruster control systems. SmallSat technology is bringing the space vehicle deployment cost within reach of a much larger market including small commercial enterprises like Cosmogia Inc.'s Dove-2 remote sensing mission for NOAA, research and educational initiatives like University of Florida's SwampSat demonstrator, and developing countries without a major space program, such as Poland's BRITE-PL for celestial observations. As the ESP technology becomes more generally available and new applications are envisioned, engineering software tools like ESPET will be essential to tailoring the thruster design to mission requirements. ESPET may also be extended to microfluidic system designs of miniaturized electrospray ionization sources for portable mass spectrometers.