Test & Measurement

Negative-Ion Time Projection Chamber Polarimeter for Measuring Polarization of Bright Transient Astrophysical Sources

Goddard Space Flight Center, Greenbelt, Maryland A negative ion time projection chamber (NI-TPC) was developed that is suitable for measuring the polarization of bright transient events. The polarization of the astrophysical source is determined by imaging photoelectron tracks created by incident x-rays interacting in a gas. The tracks drift through the gas under a uniform electric field to the readout electronics. The initial photoelectron direction is correlated with the polarization of the incident x-ray, and therefore by imaging many tracks, one can determine the polarization magnitude and direction of the incident x-rays.

Posted in: Briefs, TSP, Instrumentation, Measuring Instruments, Test & Measurement, Imaging and visualization, Test equipment and instrumentation, Test facilities


Nonlinear Swept Frequency Technique for CO2 Measurements Using a CW Laser System

The measurements would be used to significantly reduce the uncertainties in global estimates of CO2, improve climate models, and close the carbon budget for improved forecasting and policy decisions. The U.S. National Research Council recently identified the need for a near-term space mission of Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS). The primary objective of the ASCENDS mission is to make CO2 column measurements across the troposphere during the day and night over all latitudes and all seasons, and in the presence of scattered clouds. These measurements would be used to significantly reduce the uncertainties in global estimates of CO2 sources and sinks, provide an increased understanding of the connection between climate and CO2 exchange, improve climate models, and close the carbon budget for improved forecasting and policy decisions.

Posted in: Briefs, TSP, Green Design & Manufacturing, Greenhouse Gases, Lasers & Laser Systems, Test & Measurement, Carbon dioxide, Spacecraft


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, Motion Control, Software, Measuring Instruments, Analysis methodologies


Magnetic Encoders

POSITAL (Hamilton, NJ) introduced new models of IXARC magnetic encoders that combine incremental and absolute rotation measurement capabilities in a single, compact package. Absolute encoders provide a control system with a report of the rotational angle and rotation count at a specific point in time; incremental encoders provide a signal pulse each time the encoder shaft rotates by a specified angle. The hybrid encoders are based on the company’s magnetic measurement technology, and offer shock, dust, and moisture resistance. The hybrid incremental and absolute rotary encoders have communications interfaces that support both measurement modes: RS-422, HTL, or TTL for incremental readings; and SSI for absolute measurements. Available multi-turn versions can count up to 64,000 revolutions, while incremental measurements have resolutions as high as 16,384 pulses per revolution. For Free Info Visit http://info.hotims.com/55588-300

Posted in: Products, Manufacturing & Prototyping, Mechanical Components, Motion Control, Measuring Instruments


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, Mechanical Components, Measuring Instruments, Nozzles, Rocket engines, Thermal testing


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, Information Sciences, Software, Measuring Instruments, Test & Measurement, Computer simulation, Test equipment and instrumentation, Test procedures, Spacecraft


Data Recorders Prepare Orion for Splashdown Test

Data recorders and software Diversified Technical Systems (DTS) Seal Beach, CA 562-493-0158 www.dtsweb.com It’s no simple task to travel 3,600 miles into space, blaze back through Earth’s atmosphere at 20,000 mph with temperatures approaching 4,000 °F, and then splash-land into the Pacific Ocean. That’s why NASA spent three years dropping the 18,000-pound mockup of the Orion space capsule into a special test pool wired with hundreds of sensors, strain gauges, and accelerometers to measure stresses and structural integrity, as well as the safety of future astronauts onboard.

Posted in: Application Briefs, Aerospace, Data Acquisition, Measuring Instruments, Test & Measurement, Event data recorders, Flight tests, Spacecraft


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