Sensors/Data Acquisition

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.

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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.

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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.

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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).

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Free Space Optical Receiver for Data Detection and Radio Science Measurements

This technique is intended to save power, bandwidth, and scheduling demands on the spacecraft. NASA’s Jet Propulsion Laboratory, Pasadena, California For deep space communication systems, the decision of whether or not to suppress the transmitted carrier has always been an issue. For certain missions that use high data rates, the available bandwidth might be a limiting factor. In such cases, it is preferred to use a completely suppressed carrier system that is more bandwidth efficient.

Posted in: Briefs, TSP, Data Acquisition, Sensors

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Physical Characterization of Radiated and Non-Radiated Materials to Temperatures Less than 50 K

Coefficient of thermal expansion and Young’s modulus of the materials are determined via custom analytical equipment that can allow temperatures down to 20 K. NASA’s Jet Propulsion Laboratory, Pasadena, California Solar-array panels will experience very low temperatures of 50 K for the proposed Europa Clipper Mission (ECM). Solar-array panels will also undergo thermal cycling from 50 K to 133 K during the mission due to Jovian eclipsing. Unfortunately, there was no knowledge of the physical properties of the materials planned to be used down to ≈50 K, making it difficult to assess their reliability under such extreme cryogenic temperature conditions.

Posted in: Briefs, TSP, Data Acquisition, Sensors

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Gas and Vapor Sensors on Paper

These sensors can be used wherever chemical or gas sensors are used, such as in mining, security, biomedical, food processing, and agriculture. Ames Research Center, Moffett Field, California Sensors on paper have been proposed and fabricated to identify gas or vapors (chemicals). Traditional sensors are based on hard substrates such as silicon. Sensors fabricated on paper are cheaper, foldable, flexible, and bio - degradable. Paper electronics is an emerging area. Logic devices, memory, RFID (radio-frequency identification) tags, etc. have been demonstrated. Sensors on paper will be another building block to achieve complete, true paper electronics.

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