Applications of Micro-Cathode Arc Thruster as in-space propulsion subsystem for PhoneSat

Abstract

The George Washington University (GWU) has developed a scalable, efficient and relatively safe electric propulsion device, for small spacecraft applications, called the Micro-Cathode Arc Thruster (μCAT). The first on-orbit demonstration of this thruster subsystem capability is planned in the second half of 2014, as the primary experiment onboard a US Naval Academy BRICSat-P mission, utilizing a 1.5U CubeSat, for validating the performance and design. From December 2012 to September 2013, NASA Ames Research center (ARC) and GWU worked together to increase the Technology Readiness Level (TRL) of the technology by integrating a complete 3-channel μCAT subsystem with the ARC PhoneSat bus. The main objectives of the collaboration were (1) to build a test bench in which a phone, running the PhoneSat firmware and a custom designed Android App could fire several thrusters in a vacuum chamber at the same time and (2) to design a CAD model of a <;3U model that could incorporate the PhoneSat bus, the thruster avionics and the thrusters themselves. At the conclusion of experimental trials, development of embedded applications, and fabrication of compact versions of legacy (2007-2012) laboratory designs, including testing in a controlled environment, the μCAT system achieved TRL 5 equivalent status. This paper presents how the interfaces of these two systems were developed, as well as the results obtained during the testing phase. The μCAT technology has several desirable properties for applications in Space, such as high specific impulse, low energy consumption, and low input voltage range. In particular, it has a compact and simple concentric design with no moving parts for extremely high reliability that yields extended operational lifetime. In this paper, analytical studies are presented to demonstrate its effectiveness for various CubeSat class spacecraft maneuvers. Analyzing the effects of low-thrust is challenging, as small variations of orbital properties should be accurately computed over a long-time period. We present brief, simplified orbital analysis based on the secular change of orbital elements derived from orbital perturbation theory. It is shown that micro-cathode thruster can be effectively used for several phases of a CubeSat mission, including orbital regularization, and inclination changes.