Ionic Liquid Field Emission Electric Propulsion for CubeSat–Like Platforms

Developed at Alta for extremely high performance scientific missions, such as LISA Pathfinder, Field Emission Electric Propulsion (FEEP) features very high specific impulse, reduced system mass and volume, and excellent performance at very low thrust. Unlike other electric thrusters, FEEP produces no plasma and has therefore no high temperature parts, allowing for easier integration into the spacecraft. Application of FEEP to micro- and nanospacecraft platforms is made possible by the recent introduction of a simplified, lower- cost version of the thruster, replacing alkali metal propellants with more benign ionic liquids and using off-the-shelf high voltage electronics. Simplified FEEP development is currently funded by ESA as a LET-SME contract and by the EC as a part of the FP7 programme "E-Sail". Among other possible uses, the simplified FEEP system goal is to provide autonomous orbital manoeuvring and lifetime extension capability through drag compensation (or de-orbiting via deceleration) to micro- and nanosatellites, such as CubeSats, with limited impact on the on- board resources. The total propulsion system dry mass is estimated to be about 400 g. The thruster produces up to 100 μN at a specific impulse of more than 2000 s with total power consumption of about 4 W, including also the control electronics and the thermal conditioning subsystem. In this study, the Alta FEEP cube is described and highlighted as the rational solution to have a small, easy and lightweight propulsion system configuration. Simplicity and tiny dimensions are the best properties available for that CubeSat system, able to provide a 2U and 3U solution with the benefit of thrust. The thruster system occupies less than a single CubeSat unit. This makes possible a substantial change to CubeSat missions and increases their application field. Additionally, also several possible mission scenarios are outlined, some of them exclusively enabled by high-specific impulse propulsion. For instance, with a load of about 450 g ionic liquid propellant, a total impulse in excess of 8000 Ns can be delivered during 2.5 years of operation, resulting in a maximum delta-V of more than 2 km/s for a 4 kg, 3-U CubeSat