Special Coverage

NASA Supercomputer Simulations Reveal 'Noisy' Aerodynamics
Robotic Gripper Cleans Up Space Debris
Soft Robot “Walks” on Any Terrain
Defense Advanced Research Projects Agency
Using Microwaves to Produce High-Quality Graphene
Transducer-Actuator Systems for On-Machine Measurements and Automatic Part Alignment
Wide-Area Surveillance Using HD LWIR Uncooled Sensors
Heavy Lift Wing in Ground (WIG) Cargo Flying Boat
Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space

Ionization-Assisted Getter Pumping for Ultra-Stable Trapped Ion Frequency Standards

A method eliminates (or recovers from) residual methane buildup in getter-pumped atomic frequency standard systems by applying ionizing assistance. Ultra-high stability trapped ion frequency standards for applications requiring very high reliability, and/or low power and mass (both for ground-based and space-based platforms) benefit from using sealed vacuum systems. These systems require careful material selection and system processing (cleaning and high-temperature bake-out). Even under the most careful preparation, residual hydrogen outgassing from vacuum chamber walls typically limits the base pressure.

Posted in: Briefs, TSP, Physical Sciences, Waste management, Methane, Maintenance, Repair and Service Operations, Maintenance, repair, and service operations, Materials identification
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Phase-Array Approach to Optical Whispering Gallery Modulators

This technology leverages the well-defined orbital number of a whispering gallery modulator (WGM) to expand the range of applications for such resonators. This property rigidly connects the phase variation of the field in this mode with the azimuthal angle between the coupling locations.

Posted in: Briefs, TSP, Physical Sciences, Mathematical analysis, Antennas, Antennas, Acoustics, Acoustics
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Fiber-Optic Continuous Liquid Sensor for Cryogenic Propellant Gauging

An innovative fiber-optic sensor has been developed for low-thrust-level settled mass gauging with measurement uncertainty

Posted in: Briefs, TSP, Physical Sciences, Fiber optics, Fiber optics, Liquid propellants, Spacecraft fuel, Fuel sensors
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Measurement of the Length of an Optical Trap

NASA Glenn has been involved in developing optical trapping and optical micromanipulation techniques in order to develop a tool that can be used to probe, characterize, and assemble nano and microscale materials to create microscale sensors for harsh flight environments. In order to be able to assemble a sensor or probe candidate sensor material, it is useful to know how far an optical trap can “reach”; that is, the distance beyond/below the stable trapping point through which an object will be drawn into the optical trap. Typically, to measure the distance over which an optical trap would influence matter in a horizontal (perpendicular to beam propagation) direction, it was common to hold an object in one optical trap, place a second optical trap a known distance away, turn off the first optical trap, and note if the object was moved into the second trap when it was turned on. The disadvantage of this technique is that it only gives information of trap influence distance in horizontal (x–y) directions. No information about the distance of the influence of the trap is gained in the direction of propagation of the beam (the z direction).

Posted in: Briefs, TSP, Physical Sciences, Measurements, Optics, Sensors and actuators, Optics, Sensors and actuators
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Mode Tracker for Mode-Hop-Free Operation of a Laser

A mode-tracking system that includes a mode-controlling subsystem has been incorporated into an external-cavity (EC) quantum cascade laser that operates in a mid-infrared wavelength range. The mode-tracking system makes it possible to perform mode-hop-free wavelength scans, as needed for high-resolution spectroscopy and detection of trace gases. The laser includes a gain chip, a beam-collimating lens, and a diffraction grating. The grating is mounted on a platform, the position of which can be varied to effect independent control of the EC length and the grating angle. The position actuators include a piezoelectric stage for translation control and a motorized stage for coarse rotation control equipped with a piezoelectric actuator for fine rotation control. Together, these actuators enable control of the EC length over a range of about 90 μm with a resolution of 0.9 nm, and control of the grating angle over a coarse-tuning range of ±6.3° and a fine-tuning range of ±520 μrad with a resolution of 10 nrad. A mirror mounted on the platform with the grating assures always the same direction of the output laser beam.

Posted in: Briefs, Physical Sciences, Mirrors, Electronic control systems, Lasers, Spectroscopy, Electronic control systems, Lasers, Spectroscopy, Gases
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Physical Invariants of Intelligence

A program of research is dedicated to development of a mathematical formalism that could provide, among other things, means by which living systems could be distinguished from non-living ones. A major issue that arises in this research is the following question: What invariants of mathematical models of the physics of systems are (1) characteristic of the behaviors of intelligent living systems and (2) do not depend on specific features of material compositions heretofore considered to be characteristic of life?

Posted in: Briefs, Information Sciences, Analysis methodologies, Mathematical models, Biological sciences, Materials properties
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Rocket-Plume Spectroscopy Simulation for Hydrocarbon-Fueled Rocket Engines

The UV-Vis spectroscopic system for plume diagnostics monitors rocket engine health by using several analytical tools developed at Stennis Space Center (SSC), including the rocket plume spectroscopy simulation code (RPSSC), to identify and quantify the alloys from the metallic elements observed in engine plumes. Because the hydrocarbon-fueled rocket engine is likely to contain C2, CO, CH, CN, and NO in addition to OH and H2O, the relevant electronic bands of these molecules in the spectral range of 300 to 850 nm in the RPSSC have been included.

Posted in: Briefs, Information Sciences, On-board diagnostics, On-board diagnostics (OBD), Spectroscopy, On-board diagnostics, On-board diagnostics (OBD), Spectroscopy, Hydrocarbons, Rocket engines
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Research on Spoken Dialogue Systems

Research in the field of spoken dialogue systems has been performed with the goal of making such systems more robust and easier to use in demanding situations. The term “spoken dialogue systems” signifies unified software systems containing speech-recognition, speech-synthesis, dialogue management, and ancillary components that enable human users to communicate, using natural spoken language or nearly natural prescribed spoken language, with other software systems that provide information and/or services. The research is proceeding on several fronts: recognition of speech signals, syntactic and semantic parsing, language modeling, discourse analysis, and contact modeling.

Posted in: Briefs, Information Sciences, Artificial intelligence, Communication protocols, Computer software / hardware, Computer software and hardware, Artificial intelligence, Communication protocols, Computer software / hardware, Computer software and hardware
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Injecting Errors for Testing Built-in Test Software

Two algorithms have been conceived to enable automated, thorough testing of Built-in test (BIT) software. The first algorithm applies to BIT routines that define pass/fail criteria based on values of data read from such hardware devices as memories, input ports, or registers. This algorithm simulates effects of errors in a device under test by (1) intercepting data from the device and (2) performing AND operations between the data and the data mask specific to the device. This operation yields values not expected by the BIT routine. This algorithm entails very small, permanent instrumentation of the software under test (SUT) for performing the AND operations.

Posted in: Briefs, Information Sciences, Mathematical models, Computer software / hardware, Computer software and hardware, Embedded software, Computer software / hardware, Computer software and hardware, Embedded software, Test equipment and instrumentation, Test procedures
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Guidance and Control System for a Satellite Constellation

A distributed guidance and control algorithm was developed for a constellation of satellites. The system repositions satellites as required, regulates satellites to desired orbits, and prevents collisions.

Posted in: Briefs, Information Sciences, Trajectory control, Flight control systems, Flight guidance systems, Flight control systems, Flight guidance systems, Satellites
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