BIT-3
Compact and efficient iodine gridded ion thruster.
Mission enabling. Featuring high performance and unprecedented efficiency at its size.
Busek’s BIT-3 RF ion thruster is an iodine-fueled gridded ion propulsion system scheduled for launch on two deep-space CubeSat missions aboard NASA’s Space Launch System rocket in 2021. The 56-75W input propulsion system utilizes a 2.5cm diameter grid RF ion thruster (BIT-3) and a micro RF cathode (BRFC-1) as the neutralizer.
The thruster’s unprecedented performance produces thrust up to 1.1 mN and specific impulse up to 2,150 seconds. Performance results were verified with xenon and iodine propellant using a highly-accurate torsional thrust stand. As an optional add-on, Busek has developed an innovative thruster gimbal capable of desaturating reaction wheels as part of the Attitude Control System (ACS).
BIT-3 Ion Thruster Performance
System Power: 56-75 W
Thrust: Up to 1.1 mN
Specific Impulse: Up to 2150s
System Dry Mass: 1.40 kg w/ gimbal
Delta-V: Up to 2.39 km/s (14kg CubeSat)
The BIT-3 uses an inductively-coupled plasma (ICP) discharge to eliminate the need for an internal hot cathode and increase overall lifetime. The most unique feature of BIT-3 is its compatibility with iodine propellant, a demonstrated drop-in replacement for xenon in terms of thrust and Isp performance. Iodine stores as a dense solid (>2x storage density than xenon) and eliminates the need for high-pressure tanks. A 3,500 hour duration test on iodine was recently completed with the BIT-3 system.
Integrated Unit
Advances in the BIT-3 thruster and BRFC-1 neutralizer are complemented by major breakthroughs in the flight electronics. The BIT-3 power processing unit (PPU) features a ~90% efficient RF power supply with radiation-tolerant components. The state-of-the-art electronics package is highly efficient and compact.