The Busek Micro-Resistojet (MRJ) is an integrated primary and attitude control system (ACS) and leverages flight and SBIR design efforts for miniature low power valves and power management electronics.

The 9 cm x 9 cm x 10 cm system is capable of throttling performance based on available power, ranging from 3 to 15W, delivering up to 10 mN along the primary axis and 0.5 mN from each of the eight ACS thrusters. Specific impulse is 150 seconds for the primary thruster, and 80 seconds for each ACS thruster.

Resistojets are the simplest form of electric propulsion. The resistojet increases efficiency of cold gas thrusters by heating the propellant, followed by expansion through a rocket nozzle. The primary benefits of Busek’s ammonia micro-resistojet (MRJ) are higher thrust and efficiency than a typical gas system.

Busek uses ammonia propellant for several reasons including:

• relative high specific impulse
• ammonia is self pressurizing
• ammonia is benign and relatively easy to handle and store
• Busek has experience and a working knowledgebase for this propellant