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Low-Cost Solar-Simulated Radiometric Calibration Source

A novel integrating sphere system was developed for calibrating large optical sensors. Stennis Space Center, Mississippi An integrating sphere is a spherical shell that has its internal wall coated with a highly reflective, diffuse scattering material. It typically includes both entrance and exit ports where illumination sources and light monitoring sensors are added to produce a well-known uniform light source. Integrating spheres are used to calibrate radiometric instruments ranging from imagers to spectrometers. Sensors that need radiometric calibration used by NASA and the commercial aerial imaging community include aerial hyperspectral spectroradiometers, aerial multispectral cameras, and some moderate- and high-resolution satellite sensors. However, many of the larger sensors need large radiometric calibration integrating spheres, which can be costly and complex. Part of the issue is that a calibration source should simulate a solar spectra with high brightness levels. Achieving the spectral and brightness goals with traditional illumination sources, such as tungsten halogen and plasma arc lamps, requires a significant number of lamps. Traditional lamps are inefficient and generate a large amount of heat that must be dissipated. Another issue is that these calibration sources are typically manufactured using spun cast aluminum machining techniques, and because of this, a fairly thick coat of highly reflective Lambertian material must be applied to mask the manufacture-induced spun cast rings. These factors combined limit the widespread use of these radiometric calibration sources, especially for large-diameter optical sensors.

Posted in: Briefs, Sensors

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Capacitively Coupled Quantum Capacitance Detector

A large number of future NASA astrophysics missions will rely on cryogenic detectors in order to meet science goals. NASA’s Jet Propulsion Laboratory, Pasadena, California Future cryogenic far-infrared (IR) missions will require moderate-resolution far-IR spectrometers operating at the photon background limit. Full utilization of these facilities requires compact, multiplexable dispersive spectrometers with integrated detector arrays with sensitivities less than 3×10–20 W/(Hz)1/2. The detectors described here will be capable of those sensitivities.

Posted in: Briefs, Sensors

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Nanosensors for Medical Diagnosis

This technology also has homeland security and medical applications. Ames Research Center, Moffett Field, California Many diseases are accompanied by characteristic odors, and their recognition can provide diagnostic clues, guide the laboratory evaluation, and affect the choice of immediate therapy. The study of the chemical composition in human breath using gas chromatography/mass spectrometry (GC/MS) has shown a correlation between the volatile compounds and the occurrence of certain illnesses. The presence of those specific compounds can provide an indication to physiological malfunction and support the diagnosis of diseases. This condition requires an analytical tool with very high sensitivity for measurement.

Posted in: Briefs, Sensors

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Passive Voice-Enabled RFID Devices

The devices are used for sensor and RFID multifunctionality. Stennis Space Center, Mississippi Radio-Frequency IDentification (RFID) is a technology that provides automatic identification of objects, and relies on storing and remotely retrieving data using devices called RFID tags or transponders. The RFID tag is an object that can be applied to and/or incorporated into a product, animal, or person for the purpose of identification using radio waves. Some tags can even be read from several meters away and beyond the line of sight of the reader. Generally, there are three varieties of RFID tags: passive, active, or semi-passive (also known as battery-assisted). Passive tags require no internal power source, are powered by harvesting energy from various artificial energy sources and/or natural energy sources (such as voice signals, other electromagnetic waves, sunlight, vibrations, or RF noise), and are only active when a reader is nearby to power them; semi-passive and active tags require a power source to function (usually a small battery).

Posted in: Briefs, Sensors

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Lightweight, Flexible, Energy-Manageable Polymer Nanocomposites

Applications include solar power panels on aircraft wings or building roofs, and in hybrid car engines. Langley Research Center, Hampton, Virginia Solar energy has attracted keen attention because it is a unique, clean, and sustainable energy resource. It is also widely utilized as a power source in space exploration. A lightweight, durable, deployable, and highly efficient all polymer-based solar power panel was developed comprising a highly efficient thermoelectric conducting polymer composite layer and highly efficient solar absorbance/passive cooling coatings for maximizing efficiency of the power conversion.

Posted in: Briefs, TSP

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Nanocomposites for Radiation Shielding

Langley Research Center, Hampton, Virginia Currently, lead and lead-based materials are used to fabricate shields not only for X-rays, but also for other types of radiation. With the growing environmental concern about the toxicity of lead, and the high costs associated with transporting heavy lead-based shields in spacecraft, alternatives are needed for fabricating X-ray shields that are less toxic and lighter.

Posted in: Briefs, TSP

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Lightweight, High-Strength Nanocomposite Magnesium for Radiators

New material offers an exceptional balance of properties and cost. Marshall Space Flight Center, Alabama The next generation of radiators will be designed using a composite with the combination of the lowest density, highest thermal conductivity, and highest strength. A scalable, low-cost process was developed to advance state-of-the-art metal matrix thermal conductors to reach a theoretical goal of 578 W/mK (270W/mK achieved), a density less than aluminum (1.7g.cc achieved), and a yield strength over 30 ksi (≈207 MPa, 42 ksi achieved). The incorporation of nanofibers into metals has been heavily researched to improve mechanical and thermal properties of materials, with limited technical and commercial success. The problem of incorporating high-aspect-ratio, high-surface-area particles (including fiber and flake) with controlled and repeatable concentration and distribution into molten metals is a large undertaking, and must factor in the molten metal temperature, composition, and surface tension. Direct feeding of the particles does not work, as particles burn, react with the molten metal, or do not stay in the metal. Other feeding mechanisms such as auger feeding into the metal, in-situ formation, and stir casting are cost-prohibitive and not always scalable.

Posted in: Briefs

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