Physical Sciences

Fast, High-Precision Readout Circuit for Detector Arrays

The GEO-CAPE mission described in NASA’s Earth Science and Applications Decadal Survey requires high spatial, temporal, and spectral resolution measurements to monitor and characterize the rapidly changing chemistry of the troposphere over North and South Americas. High-frame-rate focal plane arrays (FPAs) with many pixels are needed to enable such measurements.

Posted in: Physical Sciences, Test & Measurement, Briefs, TSP

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A System for Measuring the Sway of the Vehicle Assembly Building

Tests have shown that the existing facility is safe. A system was developed to measure the sway of the Vehicle Assembly Building (VAB) at Kennedy Space Center. This system was installed in the VAB and gathered more than one total year of data. The building movement was correlated with measurements provided by three wind towers in order to determine the maximum deflection of the building during high-wind events.

Posted in: Physical Sciences, Test & Measurement, Briefs, TSP

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ISS Ammonia Leak Detection Through X-Ray Fluorescence

An astrophysics instrument can be used to detect and localize ISS ammonia leaks. Ammonia leaks are a significant concern for the International Space Station (ISS). The ISS has external transport lines that direct liquid ammonia to radiator panels where the ammonia is cooled and then brought back to thermal control units. These transport lines and radiator panels are subject to stress from micrometeorites and temperature variations, and have developed small leaks. The ISS can accommodate these leaks at their present rate, but if the rate increased by a factor of ten, it could potentially deplete the ammonia supply and impact the proper functioning of the ISS thermal control system, causing a serious safety risk.

Posted in: Physical Sciences, Test & Measurement, Briefs, TSP

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Hydrometeor Size Distribution Measurements by Imaging the Attenuation of a Laser Spot

Measurement of the DSD’s second moment is made by way of the Beer-Lambert law. The optical extinction of a laser due to scattering of particles is a well-known phenomenon. In a laboratory environment, this physical principle is known as the Beer-Lambert law, and is often used to measure the concentration of scattering particles in a fluid or gas. This method has been experimentally shown to be a usable means to measure the dust density from a rocket plume interaction with the lunar surface. Using the same principles and experimental arrangement, this technique can be applied to hydrometeor size distributions, and for launch-pad operations, specifically as a passive hail detection and measurement system.

Posted in: Physical Sciences, Test & Measurement, Briefs, TSP

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Victim Simulator for Victim Detection Radar

This simulator can be placed for long periods of time in environments that would be unsafe for a human subject. Testing of victim detection radars has traditionally used human subjects who volunteer to be buried in, or climb into a space within, a rubble pile. This is not only uncomfortable, but can be hazardous or impractical when typical disaster scenarios are considered, including fire, mud, or liquid waste. Human subjects are also inconsistent from day to day (i.e., they do not have the same radar properties), so quantitative performance testing is difficult. Finally, testing a multiple-victim scenario is difficult and expensive because of the need for multiple human subjects who must all be coordinated.

Posted in: Physical Sciences, Test & Measurement, Briefs, TSP

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Complementary Barrier Infrared Detector (CBIRD) Contact Methods

The performance of the CBIRD detector is enhanced by using new device contacting methods that have been developed. The detector structure features a narrow gap adsorber sandwiched between a pair of complementary, unipolar barriers that are, in turn, surrounded by contact layers. In this innovation, the contact adjacent to the hole barrier is doped n-type, while the contact adjacent to the electron barrier is doped p-type.

Posted in: Physical Sciences, Briefs

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Multimode Directional Coupler for Utilization of Harmonic Frequencies From TWTAs

The design is easily scaled to higher frequency TWTAs. A novel waveguide multimode directional coupler (MDC) intended for the measurement and potential utilization of the second and higher order harmonic frequencies from high-power traveling wave tube amplifiers (TWTAs) has been successfully designed, fabricated, and tested. The design is based on the characteristic multiple propagation modes of the electrical and magnetic field components of electromagnetic waves in a rectangular waveguide.

Posted in: Physical Sciences, Briefs, TSP

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