Following completion of the 5,600 hour qualification life test of the BPT-4000 4.5 kW Hall Thruster Propulsion System, NASA and Aerojet have undertaken efforts to extend the qualified operating range and lifetime of the thruster to support a wider range of NASA missions. The system was originally designed for orbit raising and stationkeeping applications on military and commercial geostationary satellites. As such, it was designed to operate over a range of power levels from 3 to 4.5 kW. Studies of robotic exploration applications have shown that the cost savings provided by utilizing commercial technology that can operate over a wider range of power levels provides significant mission benefits. The testing reported on here shows that the 4.5 kW thruster as designed has the capability to operate efficiently down to power levels as low as 1 kW. At the time of writing, the BPT-4000 qualification thruster and cathode have accumulated over 400 hours of operation between 1 kW-2 kW with an additional 600 hours currently planned. The thruster has demonstrated no issues with longer duration operation at low power.
Nomenclature
I d= discharge current I SP = specific impulse
Cold gas propulsion systems offer today's CubeSats a relatively simple, minimal V propulsion solution. CubeSat mission needs have been identified that would be enhanced or enabled if significant V were available in conjunction with preserving the control authority offered by cold gas propulsion systems. Examples include large scale orbit transfer for constellation deployment, proximity operations, formation-flying, de-orbit, orbit maintenance, attitude control, and momentum management. To meet these needs, Aerojet is offering the MRS-142, a 1U blow-down CubeSat High-impulse Adaptable Monopropellant Propulsion System (CHAMPS) that delivers a more than five-fold increase in total impulse compared to similarly-packaged cold gas systems. A four-thruster array, providing threeaxis attitude control as well as single-axis V, is integrated into a monolithic piston propellant tank doubling as the primary structure. To satisfy varied mission-specific propulsion system requirements, the CHAMPS design supports adjustment of the thrust level and minimum impulse via easily changeable fluid resistors and system operating pressure. Thrust vector orientation is tailored through simple modifications of the thruster nozzles. The final flight system is designed to be fully compliant with Air Force Space Command Manual 91-710.
NomenclatureA p = geomagnetic index a = semimajor axis β = ballistic coefficient, kg/m 2 c = ae/h e = eccentricity F 10.7 = solar radio flux index h = atmospheric scale height I j = modified Bessel functions of order j and argument c ρ = density ρ p = density at perigee
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