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Airborne Elastic Backscatter and Raman Polychromator for Ash Detection

Marshall Space Flight Center, Alabama Volcanic ash is a significant hazard to aircraft engine and electronics. It has caused damage to unwary aircraft and disrupted air travel for thousands of travelers, costing millions of dollars. The small, jagged fragments of rocks, minerals, and volcanic glass that constitute volcanic ash are about the size of sand and silt. Volcanic ash is hard, does not dissolve in water, is extremely abrasive and corrosive, and conducts electricity when wet. The upper winds transport the particles away to eventual dispersal in an ash cloud. Ash clouds typically form above 20,000 feet, but the lower limit of the initial cloud depends on both the height of the volcanic vent and the vigor with which material is ejected from it.

Posted in: Briefs, Sensors

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Intelligent Displacement Sensor Deployment Using MTConnect Protocol over Ethernet

The protocol interfaces to an intelligent sensor and provides data gathering using a PC application. Stennis Space Center, Mississippi Quality measurements for design validation and certification requirements sometimes require hundreds or thousands of sensors and actuators. Maintaining such a complex system is difficult, especially over an extended time period and inevitable personnel changes. Many hours are spent tracking down sensor problems related to the sensor, associated cables, mounting hardware, or some part of the data acquisition system. These are expensive, labor-intensive hours that consume valuable technical resources.

Posted in: Briefs, Sensors

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Active Remote-Sensing Radiometer

This technology can be used for security screening and security imaging, as well as automotive navigation in dust and fog conditions where machine vision performs poorly. NASA’s Jet Propulsion Laboratory, Pasadena, California Millimeter-wave (mm-wave) imaging techniques are already a popular solution for imaging through dust and fog. While mm-wave offers excellent penetration to dust when compared with infrared or optical sensing, the longer wavelengths create many problems associated with the specular response of surfaces at mm-wave. Generally, at mm-wave, the geometry and orientation of the target object has a larger influence on captured contrast than material properties by several orders of magnitude. While these effects can be somewhat mitigated with a radar imager, there is still a large contrast dependence on beam-target angle, and images are still entirely derived from geometry instead of material compositions.

Posted in: Briefs, Sensors

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High-Data-Rate Platform to Capture and Analyze Raw Baseband Clock/Data

NASA’s Jet Propulsion Laboratory, Pasadena, California The Space Communications and Navigation (SCaN) Testbed has a need to capture and analyze high-datarate (<2 Mbps required) baseband information sent over RF by the JPL Software-Defined Radio (SDR). An RF4425 front end, coupled with a MicroGate Synclink USB and custom C++ software back end, is being used to answer this need.

Posted in: Briefs

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V-FASTR Radio Transient Classifier

NASA’s Jet Propulsion Laboratory, Pasadena, California The V-FASTR (VLBA Fast Transient Experiment) system was motivated by the desire to monitor the radio sky for interesting transient events. To be confident that no interesting extragalactic event is missed, every VFASTR candidate requires human review and evaluation. Candidates consist of pulsar pulses, spurious correlated radio frequency interference (RFI), and other potentially unknown phenomena. However, the number of candidates generated by V-FASTR each day ranges from zero, to tens, to hundreds, to thousands, depending on the observational target and environmental conditions. On busy days, the volume of candidates exceeds the amount of time available for human review.

Posted in: Briefs

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Wideband, Dual-Polarized, Ultra-Low-Noise Focal Plane Array Feed for Active/Passive Microwave Remote Sensing

Goddard Space Flight Center, Greenbelt, Maryland NASA missions utilize active, passive, or both, microwave sounders with a large reflector antenna as an important component. In most of these applications, design engineers have realized that desirable science requirements (spatial and temporal resolutions) can be met only by compromising between conflicting engineering design parameters. A microwave remote sensor designed to achieve high spatial resolution would result in longer revisit time, yielding low temporal resolution and vice-versa. To overcome these conflicting requirements, the present technology advocates use of a cluster of feed horns arranged in the focal plane of the primary reflector antenna. Each feed horn produces a different footprint with appropriate overlaps covering a wide swath, allowing a high temporal resolution. Each feed horn, since they act independently, is designed to produce high spatial resolution. However, this approach has many disadvantages compared to an antenna system in which the cluster of horn feeds is made to act as a Focal Plane Array (FPA). Furthermore, the current approach does not enable maximization of the antenna gain, or immunity for radio frequency interference (RFI).

Posted in: Briefs

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RF Source Modifications to Improve Performance of an Electronegative Plasma Thruster

Marshall Space Flight Center, Alabama In traditional gridded electrostatic ion thrusters, positively charged ions are generated from a plasma discharge of noble gas propellant and accelerated to provide thrust. A separate electron source, typically a neutralizer cathode that consumes propellant, is required in the propulsion system to neutralize the ion beam after it exits the thruster, thereby maintaining overall charge balance. However, if high-electronegativity propellant gases are used, a plasma discharge can result that consists of both positive and negative ions. Such an electronegative plasma thruster has the ability to generate thrust with a quasi-neutral ion-ion plume, thus allowing for the elimination of the neutralizer cathode subsystem, reduction of propulsion system complexity, and improvement of system lifetime and operational flexibility.

Posted in: Briefs

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