Table 3 Summary of best micropropulsion systems to achieve various types of CubeSat maneuvers Maneuver type Key thruster properties Thruster types Small maneuvers (e.g., station keeping, launch error correction) Low power, small thruster, and propellant mass/volume Cold gas, electrospray, pulsed plasma Maximum orbit change given time constraints High thrust, high propellant density Green monopropellant Large orbit changes (e.g., LEO to GEO or Earth escape) High I sp , range of power and thrust Electrospray, helicon plasma, ion thruster ‡ ‡ Private communication with Colleen Marrese-Reading to

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A method for in situ erosion rate measurements of boron nitride (BN) ceramic in a vacuum chamber using radiation emission spectroscopy has been developed and initially tested. Experiments have been conducted that compare erosion amounts measured using 3D optical profilometry measurements to the emission intensity of neutral boron downstream of an ion source. It is shown that the spectrograph and imaging system used for the experiments can differentiate between boron emission and iron emission, which is one of the main difficulties in making these measurements. Langmuir probe measurements have been utilized to determine xenon ion number density where erosion occurs. These measurements have shown that where the plasma density is higher, the emission intensity of neutral boron and ionized xenon was higher, and the amount of erosion that occurred was higher. Initial results show that the amount of erosion is dependent on the operating condition of the plasma device, and this is indicated by the emission intensity of the boron in the plume. Nomenclature n i = ion number density A p = Langmuir probe surface area M i = ion mass E = electron charge I i = ion saturation current V = Langmuir Probe bias voltage