Test & Measurement

Advanced Rolling Mechanics Analysis (AROMA) 1.0

Lyndon B. Johnson Space Center, Houston, Texas AROMA uses a boundary-element formulation to calculate normal and shear pressure distributions and sub-surface stresses for elastic bodies in contact. In addition to handling static normal and sheer loading, it also solves the contact problem for rolling elements such as bearings, traction drives, and wheel-to-rail interfaces. AROMA is a powerful and flexible tool for studying the tractive forces that arise during rolling in combination with kinematic effects, such as creepage and spin that are related to rolling element alignment. This GUI-based tool was developed in MATLAB, and can run within the MATLAB environment or as a standalone application.

Posted in: Briefs, Measuring Instruments

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Nozzle Heat Flux Gauge

Marshall Space Flight Center, Alabama This innovation is a tungsten-rhenium gauge that can be placed into an aft exit cone of a rocket motor. It will measure heat flux with time for the full duration of the RSRM (reusable solid rocket motor) nozzle environment with equal response time.

Posted in: Briefs, Measuring Instruments

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Magnetic Sensitivity of a Ka-Band Isolator Measured Using the GRAIL Testbed

NASA’s Jet Propulsion Laboratory, Pasadena, California The magnetic sensitivity of a Ka-band isolator’s output phase is measured at 7 × 10–4 deg/G level. This high degree of precision is enabled by the sensitive phase measuring capabilities of a testbed built to mimic NASA’s Gravity Recovery and Interior Laboratory (GRAIL) spacecraft. Its ground-based testbed was used to measure the magnetic sensitivity of a flight-spare Ka-band isolator, and the authors found it to be 0.0052 ±0.0007 deg/G along its most sensitive axis. The GRAIL mission was able to incorporate microwave isolators into its instrumentation because the spacecraft orbited the Moon and, thus, did not travel through a permanent magnetic field as it would in a mission around Earth. Understanding this magnetic sensitivity is key to evaluating the impact an isolator would have on data quality for future gravity missions such as GRACE-FO (Gravity Recover and Climate Experiment — Follow On), a scheduled follow-on mission to GRACE, which has been mapping out Earth’s gravity for over a decade.

Posted in: Briefs, Electronics & Computers, Measuring Instruments

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Method for Performing GPS L1 C/A Measurements in Wideband Jamming and Interference

John F. Kennedy Space Center, Florida For effective range safety, global positioning system (GPS) metric tracking must be robust to interference with, and jamming of, GPS signals. The conventional approach to mitigating interference and jamming is to use a Controlled Reception Pattern Antenna (CRPA). These few-element phased arrays are used to steer nulls in the directions of interference sources, and/or to point beams in the directions of GPS satellites. The use of CRPAs is limited by their cost and size, as well as the difficulties of integrating the array into a platform. The problems are compounded for a launch vehicle, which must acquire and track GPS signals at high speed and acceleration, and undergo vibration and temperature conditions not common to CRPA use.

Posted in: Articles, Briefs, TSP

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JWST IV&V Simulation and Test (JIST) RT Logic T501 Emulator

Emulator using only software implements the behavior of a processor. Goddard Space Flight Center, Greenbelt, Maryland In order to develop a software-only test environment for the James Webb Space Telescope (JWST) mission, a solution was needed to send commands and receive telemetry between the TCTS (Telemetry and Command Test Set) and CMM-S card. The as-is solution requires the utilization of commercial off-the-shelf hardware (RT Logic Telemetrix T501 processor) and custom CMM-S hardware.

Posted in: Articles, Briefs, TSP, Electronics & Computers

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Cooling Test Samples With a Combined Convective and Conductive System to Rapidly Reach 77 K

This innovation enables rapid cooling to 77 K of James Webb Space Telescope shields, which enables hypervelocity impact testing with micro-particle spheres. Lyndon B. Johnson Space Center, Houston, Texas In this innovation, a team successfully developed and implemented a combined convective and conductive cooling system that permits rapid cooling. Using a spray system, liquid nitrogen (LN2) was injected into a test article enclosure located in the target tank that was evacuated to a lower pressure than the surrounding ambient pressure of the White Sands Test Facility (WSTF). According to the saturation curve for nitrogen, temperatures lower than 77 K can be achieved by using the evaporative process as long as the pressure remains above the triple point where nitrogen ice is formed.

Posted in: Articles, Briefs, TSP

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Guarded Two-Dimensional Flat Plate Insulation Test Calorimeter with Attach Points

Consistent test results are obtained in a cost-effective, safe, reliable, and practical manner. John F. Kennedy Space Center, Florida Insulation systems usually do not operate on their own; they must work together with a structural system that is designed to support the article being insulated. Typically this structure penetrates the insulation, degrading it in some manner, and gives a pathway for the conduction of unwanted heat. High-performance insulation systems that use reflective foils are highly anisotropic (the heat flows more easily in one direction than the others), so disturbing the temperature gradients through the material can cause much greater effects than are due to the disturbances alone.

Posted in: Articles, Briefs, TSP, Data Acquisition, Sensors

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