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Polarizing Sun Sensor

Commercial applications include agricultural, surveyor equipment, and energy conservation equipment installation. NASA’s Jet Propulsion Laboratory, Pasadena, California For a number of applications, the pointing direction towards the Sun must be known or measured. Con ventional Sun sensors determine the pointing direction towards the Sun while the Sun is in the field of view of the sensor. The disadvantage of a conventional Sun sensor is that it only operates when there is an unobstructed line of sight to the Sun. At some locations/seasons, it is virtually impossible to use a conventional Sun sensor.

Posted in: Briefs, Sensors

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Three-Axis Sun Sensor for Attitude Determination

This three-axis attitude determination sensor is based on Sun observations. NASA’s Jet Propulsion Laboratory, Pasadena, California A conventional Sun sensor determines the orientation of the Sun in two axes. If mounted on Earth in a known coordinate system, it can determine the azimuth and elevation of the Sun. When mounted on a spacecraft, it can determine the pointing direction toward the Sun. Traditionally, Sun sensors have been based on optical/detector configurations that would change the magnitude of an electrical signal based on the angular incidence of the Sun (analog Sun sensor). Other types of Sun sensors have relied on optics and a geometric pattern placed over the detectors that generated an on/off (digital) signal depending on the solar angle (digital Sun sensor).

Posted in: Briefs, Sensors

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Venus Heat Flux Sensor

NASA’s Jet Propulsion Laboratory, Pasadena, California A sensor element that consists of a thermally resistive layer made of nand p-type semiconductor elements amplifies the temperature gradient in the resistive layer that results from heat flow through the sensor. The thermoelectric array provides greater accuracy and sensitivity over a traditional thermopile arrangement for heat flux measurement. The thermoelectric sensor array is an adaptation of technology developed for generating electricity in radioisotope thermoelectric generators that operate with internal temperatures in excess of those at Venus. The technology is used in a different manner in that, instead of generating electrical power, it measures heat flow using a temperature differential output and a voltage output.

Posted in: Briefs, TSP, Sensors

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RFID Waveguide, Antenna, and Cavity Sensors

Potential uses include automated inventory management applications such as dispensing of pills, grains, liquids, or other items to which attachment of RFID tags is impossible. Lyndon B. Johnson Space Center, Houston, Texas Radio frequency identification (RFID) tags consist of an antenna and an integrated circuit. The antenna is typically the more costly of the two components, and, by far, the largest. As antenna size decreases, efficiency also decreases, and the read range is also reduced accordingly. Moreover, some items are too small to permit RFID tag attachment. Other small items tend to be of such low value that the tag cost approaches the value of the individual item, rendering RFID item level tracking ineffective.

Posted in: Briefs, TSP, Sensors

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Sensor Planning Service for Submitting Requests to Task the EO-1

This interface allows the user to submit requests for observation of instruments on satellite. NASA’s Jet Propulsion Laboratory, Pasadena, California A Web interface framework has been developed that implements the Open Geospatial Consortium (OGC) Sensor Planning Service (SPS) specification. The OGC defines the SPS to “provide information concerning content and encoding of the parameter data that has to be provided in order to task a sensor.” This interface allows the user to provide input parameters to submit requests for observation of instruments on the Earth Observing-1 (EO-1) satellite.

Posted in: Briefs, Sensors

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Transparent and Ubiquitous Sensing Technology

Langley Research Center, Hampton, Virginia Traditionally, sensor systems are considered independent systems that are separately designed, manufactured, and integrated into a target system such as an aircraft. In most cases, this is a complex and costly process including sensor design, installation, wiring, testing, and maintenance. The sensor size, installation method, wiring, and cost limit the sensor node in very limited numbers and positions. Moreover, because of limitations, there are many places where the sensor system cannot reach.

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Position Sensing and Formation Flying Using Optical Beacons

Two beacons on the starshade do the job. NASA’s Jet Propulsion Laboratory, Pasadena, California One way of imaging exoplanets around nearby stars is to use a starshade in conjunction with a space telescope. Typically, the starshade, which resembles a sunflower in outline, is ~ 30 meters in diameter. The starshade is flown about 50,000 km in front of the telescope, and when positioned directly in the telescope’s line of sight to the star, blocks the starlight, casting a deep shadow onto the telescope. Exoplanets orbiting the star and having a small angle to the line of sight will be visible because the starlight is extinguished. During the observation period, the position of the telescope needs to be maintained within about 1 m of the center of the shadow for maximum shading of the starlight.

Posted in: Briefs, Sensors

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