Flight Development of Iodine BIT-3 RF Ion Propulsion System for SLS EM-1 CubeSats

Busek previously developed a 3cm RF ion thruster known as BIT-3 that was the world\u27s first iodinefueled gridded ion thruster. The 60W prototype thruster completed a 500-hour endurance test on iodine and was shown capable of delivering 1.3mN thrust and 3200sec Isp nominally, excluding neutralizer flow. This exceptional performance, combined with the many benefits of iodine propellant, has led to a number of CubeSat flight opportunities on NASA\u27s SLS EM-1 mission. The first confirmed EM-1 mission for the thruster is onboard the 6U Lunar IceCube spacecraft that is being developed by Morehead State University and its partners. This paper will describe the technological advances made to date on the BIT-3 system and the remaining development to flight readiness. Specifically it will include updates on the thruster design and power optimization, measured thruster and Isp performance with an innovative RF cathode neutralizer, and details regarding the flight iodine feed system and power electronics module. In addition, it will include an overview of the BIT-3 system\u27s digital command/control structure and mechanical interfaces in the context of the Lunar IceCube bus. The BIT-3 ion thruster\u27s ability to use iodine as propellant is a huge game-changer for CubeSats, as iodine is stored in high-density solid form (4.9g/cc vs. xenon\u27s 1.95g/cc at 2000psi) devoid of bulky pressure vessels. The solid storage property makes iodine-fueled propulsion systems safe and facilitates compliance with range safety requirements, which is especially important for secondary payloads. The sub-Torr storage vapor pressure also allows for thin-walled, lightweight and conformal tanks that could further reduce the overall volume and mass budget impact without compromising performance. For example, Lunar IceCube\u27s tightly packaged 2U iodine BIT-3 system can provide more than 2km/s delta-V to a 6U/14kg CubeSat for lunar or other deep-space missions. Such unprecedented capability can help increase the practicality and appeal of CubeSats alike, ultimately gaining acceptance within the science community as a viable platform for future robotic exploration missions to destinations currently unachievable with small satellites