2019.B.3.4. Interplanetary Cubesat Propulsion System using Electrospray assisted Tethering (PorcuSat)

Author(s)

Roshan John Alumootil (1)

SRM University, India

Session

B.3

Keywords

Electrospray, tethering, gas giants

Abstract

PORCUSAT system consists of an integrated Electrospray thruster array and Electrodynamic tethers, with each component having its designated function. In this system, the electrospray thruster array will be the main propulsive contributor in the first stage, while the tether array plays a major role in the presence of considerable magnetic field.
Our aim is to extract the best of both systems while fulfilling the clause of low weight, low power and economy in the system.
Electrospray propulsion is based on the electrostatic extraction and acceleration of positive and negative ions from an ionic liquid, a zero-vapor pressure conductive salt that remains in the liquid phase at room temperature. Intense electric fields of the order of 1V/m achieved at the tip of electrically stressed menisci called Taylor cones, formed at the ends of sharp emitter structures. Emission is achieved from here where ions are accelerated and passed through a downstream extractor thus generating thrust. It has already been tested on board the LISA Pathfinder (ST-7) mission.
Electrodynamic tethers utilize crossed electric and magnetic fields to induce a perpendicular force. The magnetic field comes from solar flare activity and high magnetic fields in gaseous giants and the electric field comes from a flowing current though a tether (conductive wire) pointing towards earth, completely independent of propellant.
PORCUSAT once in the interplanetary orbit, will utilise the Electrospray arrays to generate thrust for acceleration, utilising just the liquid phase propellant and solar cells thus requiring no pressuring, valves, or complex feeding systems because the fuel is driven by capillary forces induced by the ion evaporation process.
The use of tether for orbital corrections instead of the sole electrospray will save a lot of propellant and avoid the dangers of orbital deviation, satellites like the Voyager was subjected to. It can also be used for descent into planetary orbits and power generation.
Evaluation has been done based on the following performance parameters: -Specific impulse (Isp), thrust, mass, power consumption, delta V, ease of fabrication and cost.