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Plasma-Based Detector of Outer-Space Dust Particles

A report presents a concept for an instrument to be flown in outer space, where it would detect dust particles — especially those associated with comets. The instrument would include a flat plate that would intercept the dust particles. The anticipated spacecraft/dust-particle relative speeds are so high that the impingement of a dust particle on the plate would generate a plasma cloud. Simple electric dipole sensors located equidistantly along the circumference of the plate would detect the dust particle indirectly by detecting the plasma cloud. The location of the dust hit could be estimated from the timing of the detection pulses of the different dipoles. The mass and composition of the dust particle could be estimated from the shapes and durations of the pulses from the dipoles. In comparison with other instruments for detecting hypervelocity dust particles, the proposed instrument offers advantages of robustness, large collection area, and simplicity.

Posted in: Briefs, TSP

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Holographic Solar Photon Thrusters

A document discusses a proposal to incorporate holographic optical elements into solar photon thrusters (SPTs). First suggested in 1990, SPTs would be systems of multiple reflective, emissive, and absorptive surfaces (solar sails) that would be attached to spacecraft orbiting the Earth to derive small propulsive forces from radiation pressures. An SPT according to the proposal would include, among other things, a main sail. One side of the sail would be highly emissive and would normally face away from the Earth. The other side would be reflective and would be covered by white-light holographic images that would alternately become reflective, transmissive, and absorptive with small changes in the viewing angle. When the spacecraft was at a favorable orbital position, the main sail would be oriented to reflect sunlight in a direction to maximize the solar thrust; when not in a favorable position, the main sail would be oriented to present a substantially absorptive/emissive aspect to minimize the solar drag. By turning the main sail slightly to alternate between the reflective and absorptive/emissive extremes, one could achieve nearly a doubling or halving of the radiational momentum transfer and, hence, of the solar thrust.

Posted in: Briefs

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Correction for Thermal EMFs in Thermocouple Feedthroughs

Expensive thermocouple-alloy multipin hermetic feedthrough connectors are no longer necessary. A straightforward measurement technique provides for correction of thermal-electromotive- force (thermal-EMF) errors introduced by temperature gradients along the pins of non-thermocouple- alloy hermetic feedthrough connectors for thermocouple extension wires that must pass through bulkheads. This technique is an alternative to the traditional technique in which the thermal-EMF errors are eliminated by use of custom-made multipin hermetic feedthrough connectors that contain pins made of the same alloys as those of the thermocouple extension wires.

Posted in: Briefs, TSP

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Generating Breathable Air Through Dissociation of N2O

Air-supply systems can be made to weigh less and/or operate longer.

Posted in: Briefs

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High-Performance Scanning Acousto-Ultrasonic System

This system reveals flaws that cannot otherwise be detected nondestructively. A high-performance scanning acousto-ultrasonic system, now undergoing development, is designed to afford enhanced capabilities for imaging microstructural features, including flaws, inside plate specimens of materials. The system is expected to be especially helpful in analyzing defects that contribute to failures in polymer- and ceramic-matrix composite materials, which are difficult to characterize by conventional scanning ultrasonic techniques and other conventional nondestructive testing techniques.

Posted in: Briefs, TSP

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Water and Air Measures That Make PureSense

Each day, we read about mounting global concerns regarding the ability to sustain supplies of clean water and to reduce air contamination. With water and air serving as life's most vital elements, it is important to know when these environmental necessities may be contaminated, in order to eliminate exposure immediately.

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Dynamic Pupil Masking for Phasing Telescope Mirror Segments

Piston and tilt adjustments could be performed more efficiently. A method that would notably include dynamic pupil masking has been proposed as an enhanced version of a prior method of phasing the segments of a primary telescope mirror. The method would apply, more specifically, to a primary telescope mirror that comprises multiple segments mounted on actuators that can be used to tilt the segments and translate them along the nominal optical axis to affect wavefront control in increments as fine as a fraction of a wavelength of light. An apparatus (see figure) for implementing the proposed method would be denoted a dispersedfringe- sensor phasing camera system (DPCS).

Posted in: Photonics, Briefs, TSP

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