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Larson, C. A.

Publications and source records attributed to Larson, C. A..

4 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Effects of anode material on arcjet performance

Anodes fabricated from four different materials were tested in a modular arcjet thruster at 1 kW power level on nitrogen/hydrogen mixtures. A two-percent thoriated tungsten anode served as the control. Graphite was chosen for its ease in fabrication, but experienced severe erosion in the constrictor and diverging side. Hafnium carbide and lanthanum hexaboride were chosen for their low work functions but failed due to thermal stress and reacted with the propellant. When compared to the thoriated tungsten nozzle, thruster performance was significantly lower for the lanthanum hexaboride insert and the graphite nozzle, but was slightly higher for the hafnium carbide nozzle. Both the lanthanum hexaboride and hafnium carbide nozzle operated at higher voltages. An attempt was made to duplicate higher performance hafnium carbide results, but repeated attempts at machining a second anode insert were unsuccessful. Graphite, hafnium carbide, and lanthanum hexaboride do not appear viable anode materials for low power arcjet thrusters.

Sankovic, John M.↗
NASA NTRS1977

NASA - selected life science experiments for the first NASA/ESA Spacelab flight 1980

Spacelab 1 will carry 17 NASA-sponsored research projects. Seven of these investigations will concern the life sciences. Because of NASA's interest in space motion sickness, two vestibular studies will be conducted. Two other experiments will be concerned with the effects of spaceflight on the hematologic system. The fifth life science study will involve nutations in plant organs. The sixth investigation will examine the effects of the Spacelab environment on circadian rhythms in microorganisms. Finally, cosmic radiation inside the Spacelab will be mapped. These seven life science experiments represent both basic and applied areas of research.

Larson, C. A.↗
NASA NTRS1974

Human spatial orientation in the pitch dimension

Two experiments were conducted. In Experiment I, each of eight Ss attempted to place himself at 13 different goal orientations between prone and supine. Deviations of achieved body pitch angles from goal orientations were determined. In Experiment II, each of eight Ss attempted to align a visual target with his morphological horizon while he was placed at each of the 13 goal orientations. Changes in settings of the target were examined. Results indicate that Ss underestimate body pitch when they are tilted less than 60 deg backward or forward from the vertical, overestimate body pitch when they are nearly prone, and accurately estimate body pitch when they are nearly supine. In contrast, Ss set the visual target maximally above the morphological horizon when they are tilted 30 deg forward from the vertical. The findings are discussed in terms of common and different physiological mechanism that may underlie judgments of these types.

Cohen, M. M.↗