Considerations for a multi-modal electrospray propulsion system

Abstract

Micro- and nano-satellites have begun to garner significant interest within the space craft community as economic trends encourage a shift away from larger, stand-alone satellite platforms. In particular, CubeSats have emerged as popular, economic alter natives to traditional satellites which might also facilitate low-cost space access for academia and developing nations. One of the foremost remaining obstacles to the widespread deployment of these spacecraft is the lack of suitable propulsion, which has severely limited the scope of prior CubeSat missions. While these spacecraft have gained traction by virtue of their economical size, the same quality has imposed unique propulsion demands which have continued to elude traditional thruster concepts. The ion Electrospray Propulsion System (iEPS) is a microelectromechanical (MEMS) based electrostatic thruster for space propulsion applications. This technology makes use of ionic liquid ion sources (ILIS) and a porous emitter substrate to obviate the need for cumbersome ancillary components and achieve the spatial and power characteristics that could lend feasibility to active micro/nano-satellite propulsion. This thesis introduces the iEPS concept and highlights the characteristics that make it attractive as a means of CubeSat propulsion. Specifically, its bimodal propulsion characteristics are presented alongside a discussion of the constant power Isp modulation mechanism that makes this unique capability possible. A simple demonstration of the variable Isp concept is reported, and a brief exploration of the performance implications is used to suggest a direction for taking it to operational maturity.