275 Terrestrial Experiments   When compressed dry air was applied to the gas inlet of the venturi eductor, the partial vacuum created  by the eductor was found to immediately begin feeding lunar regolith simulant material into the input air  flow to the eductor, thus producing a very dense flow  of dusty air that exited th e eductor along the convey  pipe towards the cyclone separator s. Tephra, being less dense than NU-LHT-2M and having a different  particle size distribution, was found to be relatively  easier to convey pneumat ically than NU-LHT-2M.  Although, the supply container had a flat bottom rather than a funnel shape in order to reduce the overall  height of the container, each simulant material wa s successfully educted from the center of the supply  container’s base plate. The total amount of mate rial that was transferred from the regolith supply  container depended on the magnitude of the air pressure applied to the gas inlet of the eductor, and on the efficiency by which the regolith simulant could be fluidized within the container before being drawn out by the eductor.    The dusty air flow that was produc ed at the eductor traveled a vertical height of 1.5 m before entering the  first cyclone. Most of the granular material collected by the first cyclone exited the solids outlet port at the  bottom of the cyclone to be deposited into the regol ith discharge container. The dusty exhaust gas that  exits from the top of any cyclone contains fine particles having sizes typically no larger than nine times  the cut diameter of the cyclone. However, the actual si ze distribution of the particles contained in the flow  between our two series cyclones could not be determined without disturbing the dynamics of the dusty air  flow. The exhaust gas from the first cyclone became the input dusty gas flow for the smaller second cyclone, which was designed to have a cut diameter of  a one micron or less. However, due to the very  dense flow of dusty air (also observed in 1/6-g) ent ering the second cyclone, it was not possible to  operate the second cyclone as an electrocyclone, which only performs effectively on a dilute particle input  flow that was not able to be achieved using only two cyclones separators connected in series. Since the  regolith feed to the eductor was not being metered du ring the terrestrial and reduced gravity tests, the  continuous dense flow of dusty air overwhelmed the cyclones.   The supply container would typically be  filled with 15 – 17 kg of lunar regolith simulant. Each of the lunar  regolith simulants, NU-LHT-2M and Tephra, was able to be pneumatically transferred from the center of a  flat-bottom regolith supply container. With some fluidiza tion of the simulant in the supply container, it was  possible to transfer all but ~1 kg of simulant to the discharge container, which se rved as a mockup of an  ISRU reactor chamber. Depending on the effectiveness of  the fluidization of the granular material inside  the supply container, typical mass transfer rates of 2 – 4 kg/min were achievable with an unmetered regolith feed to the eductor. Although metering the fe ed of regolith to the eductor would reduce the mass  transfer rate and lengthen the overall transfer time, this  would likely result in an improved performance of  the cyclone separators in removing particles from the dusty air flow and depositing these particles into the regolith discharge container. These tradeoffs must be considered in designing a pneumatic regolith transfer system for lunar operations.    Reduced Gravity Experiments

A flight rig was constructed at  NASA Kennedy Space Center to meet the safety requirements for  conducting reduced gravity (1/6-g) tests onboard an aircraft. The aircraft achi eves short periods of  reduced gravity by flying a series of parabolic flight trajectories. During t he parabolic trajectory, the aircraft  also experiences periods of increased gravity (~1.8 g) which the experiment must also endure. The RGF  pneumatic transfer experiment was initiated immediately after the lunar gravity condition was achieved and was terminated approximately 25 se c later at the end of the reduced gravity experience. Figure 11  shows the pneumatic transfer of Tephra under simulated lunar gravity conditions.   As in the terrestrial tests, it was observed that most of the Tephra tr ansferred from the supply container to  the discharge container located beneath the cycl one, but the dense flow ov erwhelmed the cyclone  separators. Insufficient visibility through the secondary containment box  prevented the precise  determination of the number of par abolas required to transfer the Tephra under 1/6-g conditions.  Although the mass transfer rate of Tephra could not be determined, it was obse rved that approximately  NASA/CP-2010-216272