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Simulator for Testing Spacecraft Separation Devices

A report describes the main features of a system for testing pyrotechnic and mechanical devices used to separate spacecraft and modules of spacecraft during flight. The system includes a spacecraft simulator [also denoted a large mobility base (LMB)] equipped with air thrusters, sensors, and data-acquisition equipment. The spacecraft simulator floats on air bearings over an epoxy-covered concrete floor. This free-flotation arrangement enables simulation of motion in outer space in three degrees of freedom: translation along two orthogonal horizontal axes and rotation about a vertical axis. The system also includes a static stand. In one application, the system was used to test a boltretraction system (BRS) intended for separation of the lifting-body and deorbitpropulsion stages of the X-38 spacecraft. The LMB was connected via the BRS to the static stand, then pyrotechnic devices that actuate the BRS were fired. The separation distance and acceleration were measured. The report cites a document, not yet published at the time of reporting the information for this article, that is said to present additional detailed information.

Posted in: Test & Measurement, Briefs

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Compensating for Effects of Humidity on Electronic Noses

Corrections are derived from outputs of separate humidity and temperature sensors.A method of compensating for the effects of humidity on the readouts of electronic noses has been devised and tested. The method is especially appropriate for use in environments in which humidity is not or cannot be controlled — for example, in the vicinity of a chemical spill, which can be accompanied by large local changes in humidity.

Posted in: Physical Sciences, Briefs, TSP

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Brush/Fin Thermal Interfaces

High thermal conductance sliding interfaces can be achieved.Brush/fin thermal interfaces are being developed to increase heat-transfer efficiency and thereby enhance the thermal management of orbital replaceable units (ORUs) of electronic and other equipment aboard the International Space Station. Brush/fin thermal interfaces could also be used to increase heat-transfer efficiency in terrestrial electronic and power systems.

Posted in: Physical Sciences, Briefs

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Multispectral Scanner for Monitoring Plants

A multispectral scanner has been adapted to capture spectral images of living plants under various types of illumination for purposes of monitoring the health of, or monitoring the transfer of genes into, the plants. In a health-monitoring application, the plants are illuminated with full-spectrum visible and near infrared light and the scanner is used to acquire a reflected- light spectral signature known to be indicative of the health of the plants. In a gene-transfer-monitoring application, the plants are illuminated with blue or ultraviolet light and the scanner is used to capture fluorescence images from a green fluorescent protein (GFP) that is expressed as result of the gene transfer. The choice of wavelength of the illumination and the wavelength of the fluorescence to be monitored depends on the specific GFP.

Posted in: Physical Sciences, Briefs

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Improved Cryostat for Cooling a Wide Panel

Less technician time and lower consumption of helium translate to lower cost.An improved cryostat has been developed for cooling a wide panel evenly over its surface to a temperature of -423 °F (-253 °C) by use of liquid helium. Originally, the cryostat was to be used in measuring apparent strains in wide aluminum/ lithium panels as functions of temperature in order to develop data for temperature compensation of the readings of strain gauges on a tank containing liquid hydrogen. Relative to the cryostat used previously for this purpose, the improved cryostat can be prepared for a test in less time, and it loses less helium during each test.

Posted in: Physical Sciences, Briefs

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Current Pulses Momentarily Enhance Thermoelectric Cooling

Transient cooling could be attractive for some semiconductor devices. The rates of cooling afforded by thermoelectric (Peltier) devices can be increased for short times by applying pulses of electric current greater than the currents that yield maximum steady-state cooling. It has been proposed to utilize such momentary enhancements of cooling in applications in which diode lasers and other semiconductor devices are required to operate for times of the order of milliseconds at temperatures too low to be easily obtainable in the steady state. In a typical contemplated application, a semiconductor device would be in contact with the final (coldest) somewhat taller stage of a multistage thermoelectric cooler. Steady current would be applied to the stages to produce steady cooling. Pulsed current would then be applied, enhancing the cooling of the top stage momentarily.

Posted in: Physical Sciences, Briefs

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Calculating Mass Diffusion in High-Pressure Binary Fluids

This model could contribute to understanding of high-pressure combustion. A comprehensive mathematical model of mass diffusion has been developed for binary fluids at high pressures, including critical and supercritical pressures. Heretofore, diverse expressions, valid for limited parameter ranges, have been used to correlate high-pressure binary mass- diffusion- coefficient data. This model will likely be especially useful in the computational simulation and analysis of combustion phenomena in diesel engines, gas turbines, and liquid rocket engines, wherein mass diffusion at high pressure plays a major role.

Posted in: Physical Sciences, Briefs, TSP

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