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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

He II emission from solar flares

The first monochromatic images of a solar flare in the 4686-angstrom line of He II are presented. The observations were obtained in the intense (X10) flare 1984 May 20. The emission comes from footprint kernels with peak intensity 3.3 times the photosphere, or 0.9 times after subtraction of photospheric background and continuum. This value is about twice that recorded by spectroscopic observers and far exceeds most published data for the intensity of the resonance line at 304 angstroms and the Balmer alpha line of He II at 1640 angstroms. The intensities of the He II lines were calculated for a range of temperature and electron density, using a six-level atom with enhanced XUV incoming flux.

Zirin, H.↗
NASA NTRS1986

Deep levels in as-grown and Si-implanted In(0.2)Ga(0.8)As-GaAs strained-layer superlattice optical guiding structures

Trap levels in about 2-micron In(0.2)Ga(0.8)As(94 A)/GaAs(25 A) strained-layer superlattices, suitable for optical waveguides, have been identified and characterized by deep-level transient spectroscopy and optical deep-level transient spectroscopy measurements. Several dominant electron and hole traps with concentrations of approximately 10 to the 14th/cu cm, and thermal ionization energies Delta-E(T) varying from 0.20 to 0.75 eV have been detected. Except for a 0.20-eV electron trap, which might be present in the In(0.2)Ga(0.8)As well regions, all the other traps have characteristics similar to those identified in molecular-beam epitaxial GaAs. Of these, a 0.42-eV hole trap is believed to originate from Cu impurities, and the others are probably related to native defects. Upon Si implantation and halogen lamp annealing, new deep centers are created. These are electron traps with Delta-E(T) = 0.81 eV and hole traps with Delta-E(T) = 0.46 eV. Traps occurring at room temperature may present limitations for optical devices.

Dhar, S.↗
NASA NTRS1986

Flight evaluation of a precision landing task for a powered-lift STOL aircraft

A flight research experiment was conducted with the NASA-Ames Research Center's Quiet Short-Haul Research Aircraft to determine the factors which influence the touchdown distribution for a powered-lift STOL aircraft. The pilots were given two tasks for each of a series of precision approaches flown using a microwave landing system (MLS) in simulated instrument meteorological conditions. They flew the aircraft, with forward vision obscured by a screen, to a 100-ft decision height using a flightpath-oriented, color electronic display and one of four levels of control augmentation. Approaches were flown along a nominal 6 deg glidepath, as well as to calibrated offsets at the decision height to establish a variety of initial conditions for the landing task. The screen was removed at the decision height and the pilot was briefed to land in a 200 foot touchdown zone of the STOLport with a sink rate less than 5 ft/sec. Statistical performance envelopes and pilot ratings are used to describe the results of this experiment. The data generated are expected to be useful for establishing STOL aircraft operating requirements and STOL MLS approach criteria.

Watson, D. M.↗
NASA NTRS1986

Effects of high energy radiation on the mechanical properties of epoxy/graphite fiber reinforced composites

The epoxy resin system formed by tetraglycidyl 4,4'-diamino diphenyl methane (TGDDM) and 4,4'-diamino diphenyl sulfone (DDS) was characterized by dynamic mechanical analysis and differential scanning calorimetry. Dynamic mechanical properties of graphite fiber epoxy composite specimens formulated with two different adhesive systems (NARMCO 5208, NARMCO 5209) were determined. The specimens were exposed to varying dose levels of ionizing radiation (0.5 MeV electrons) with a maximum absorbed dose of 10,000 Mrads. Following irradiation, property measurements were made to assess the influence of radiation on the epoxy and composite specimens. The results established that ionizing radiation has a limited effect on the properties of epoxy and composite specimens.

Fornes, R. E.↗
NASA NTRS1986

Noncollisional excitation of low-lying states in gaseous nebulae

Consideration is given to the effects of processes other than electron collisional excitation on the energy level populations of species of C, N, and O. It is found that dielectronic as well as direct-radiative recombination may contribute significantly and in some cases be the major input to populating the low-lying metastable levels. It is concluded that the most pronounced changes occur when there is a large effective recombination coefficient to a level and when T(e) is low. The most dramatic change among the forbidden lines occurs for the O II forbidden lines.

Rubin, Robert H.↗
NASA NTRS1990

The photoelectron spectroscopy of ZnCl2

The ionization energies (IEs) corresponding to the Cl ligand electrons and the Zn 3d electrons in ZnCl2, computed using large Gaussian basis sets and a high level of correlation treatment, are presented. The IEs for the Cl ligand electrons are in excellent agreement with those determined from photoelectron spectra. The IEs corresponding to the Zn 3d electrons agree with experiment relatively well in absolute magnitude, but differ in order. The vibrational frequencies of the ground state agree very well with experiment, and predictions are made for the corresponding frequencies in the positive ion.

Bauschlicher, Charles W., Jr.↗
NASA NTRS1992

Current-driven plasma acceleration versus current-driven energy dissipation. III - Anomalous transport

In the present paper the linear stability description and weak turbulence theory are used to develop a second order description of wave-particle transport and anomalous dissipation. The goal is to arrive at anomalous transport coefficients that can be readily included in fluid flow codes. In particular, expressions are derived for the heating rates of ions and electrons by the unstable waves and for the electron-wave momentum exchange rate that controls the anomalous resistivity effect. Comparative calculations were undertaken assuming four different saturation models: ion trapping, electron trapping, ion resonance broadening, and thermodynamic bound. A foremost finding is the importance of the role of electron Hall parameter in scaling the level of anomalous dissipation for the parameter range of the MPD thruster plasma. Polynomial expressions of the relevant transport coefficients cast solely in terms of macroscopic parameters are also obtained for inclusion in plasma fluid codes for the self-consistent numerical simulation of real thruster flows including microturbulent effects.

Choueiri, Edgar Y.↗
NASA NTRS1991

An overview of autonomous rendezvous and docking system technology development

The Centaur upper stage was selected for an airborne avionics modernization program. The parts used in the existing avionics units were obsolete. Continued use of existing hardware would require substantial redesign, yet would result in the use of outdated hardware. Out of date processes, with very expensive and labor intensive technologies, were being used for manufacturing. The Atlas/Centaur avionics were to be procured at a fairly high rate that demanded the use of modern components. The new avionics also reduce size, weight, power, and parts count with a dramatic improvement in reliability. Finally, the cost leverage derived from upgrading the avionics as opposed to any other subsystem for the existing Atlas/Centaur was a very large consideration in the upgrade decision. The upgrade program is a multiyear effort that began in 1989. It includes telemetry, guidance and navigation, control electronics, thrust vector control, and redundancy levels.

Nelson, Kurt D.↗
NASA NTRS1993

Spatial interpretation of NASA's Marshall Space Flight Center Payload Operations Control Center using virtual reality technology

In its search for higher level computer interfaces and more realistic electronic simulations for measurement and spatial analysis in human factors design, NASA at MSFC is evaluating the functionality of virtual reality (VR) technology. Virtual reality simulation generates a three dimensional environment in which the participant appears to be enveloped. It is a type of interactive simulation in which humans are not only involved, but included. Virtual reality technology is still in the experimental phase, but it appears to be the next logical step after computer aided three-dimensional animation in transferring the viewer from a passive to an active role in experiencing and evaluating an environment. There is great potential for using this new technology when designing environments for more successful interaction, both with the environment and with another participant in a remote location. At the University of North Carolina, a VR simulation of a the planned Sitterson Hall, revealed a flaw in the building's design that had not been observed during examination of the more traditional building plan simulation methods on paper and on computer aided design (CAD) work station. The virtual environment enables multiple participants in remote locations to come together and interact with one another and with the environment. Each participant is capable of seeing herself and the other participants and of interacting with them within the simulated environment.

Lindsey, Patricia F.↗
NASA NTRS2002

Current Status of High Performance Large Format Si:As IBC Detectors for SOFIA-like Applications

Airborne and space telescope astronomical observations in the 5-25 micrometer wavelength region, are critical for understanding the physical conditions, composition, chemistry, and excitation of many environments in the interstellar medium, external galaxies, solar system objects, extra-solar systems, and stars. The scientific impact is particularly unique in the 5-8 micrometer and 14-25 micrometer regions which are inaccessible or poorly observed from ground-based observatories. Large-format area mid-infrared (MIR) detectors sensitive over these wavelengths and operable under moderate backgrounds (greater than 10(circumflex)6 e-/s at R=2000, 10(micrometers)) are essential for efficient large-area survey imaging and for taking moderate resolution spectra over a large spectral range. Both SOFIA and passively cooled Explorer observatories could benefit from this technology. Current first-light SOFIA instruments use small-format MIR FPA's of sizes 128x128 and 256x256, With the collaboration of Raytheon Infrared Operations (RIO), NASA-ARC has been testing the first device of this kind, a combination of 1) the ALADDIN III readout multiplexer, cryo-processed for 6K operation, with 2) SIRTF IRAC-like Sides IBC detector material. designed for higher QE and low dark current. Here we report requirements. design, and initial fabrication and testing of the first 1024x1024 Si:As IBC mid-IR detector array for these conditions. This device has exhibited low dark current, moderate noise levels, and greater than 200,000 electron linear well size at 6K operation. We conclude with suggestions for future device development for optimal performance under moderate background, SOFIA- and low Earth orbit observing conditions.

Ennico, Kimberly↗
NASA NTRS2003

In-Flight Thermal Performance of the Geoscience Laser Altimeter System (GLAS) Instrument

The Geoscience Laser Altimeter System (GLAS) instrument is NASA Goddard Space Flight Center's first application of Loop Heat Pipe technology that provides selectable/stable temperature levels for the lasers and other electronics over a widely varying mission environment. GLAS was successfully launched as the sole science instrument aboard the Ice, Clouds, and Land Elevation Satellite (ICESat) from Vandenberg AFB at 4:45pm PST on January 12, 2003. After SC commissioning, the LHPs started easily and have provided selectable and stable temperatures for the lasers and other electronics. This paper discusses the thermal development background and testing, along with details of early flight thermal performance data.

Grob, Eric↗
NASA NTRS2004

Future Concepts for Modular, Intelligent Aerospace Power Systems

Nasa's resent commitment to Human and Robotic Space Exploration obviates the need for more affordable and sustainable systems and missions. Increased use of modularity and on-board intelligent technologies will enable these lofty goals. To support this new paradigm, an advanced technology program to develop modular, intelligent power management and distribution (PMAD) system technologies is presented. The many benefits to developing and including modular functionality in electrical power components and systems are shown to include lower costs and lower mass for highly reliable systems. The details of several modular technologies being developed by NASA are presented, broken down into hierarchical levels. Modularity at the device level, including the use of power electronic building blocks, is shown to provide benefits in lowering the development time and costs of new power electronic components.

Button, Robert M.↗
NASA NTRS2004

Alternative Test Methods for Electronic Parts

It is common practice within NASA to test electronic parts at the manufacturing lot level to demonstrate, statistically, that parts from the lot tested will not fail in service using generic application conditions. The test methods and the generic application conditions used have been developed over the years through cooperation between NASA, DoD, and industry in order to establish a common set of standard practices. These common practices, found in MIL-STD-883, MIL-STD-750, military part specifications, EEE-INST-002, and other guidelines are preferred because they are considered to be effective and repeatable and their results are usually straightforward to interpret. These practices can sometimes be unavailable to some NASA projects due to special application conditions that must be addressed, such as schedule constraints, cost constraints, logistical constraints, or advances in the technology that make the historical standards an inappropriate choice for establishing part performance and reliability. Alternate methods have begun to emerge and to be used by NASA programs to test parts individually or as part of a system, especially when standard lot tests cannot be applied. Four alternate screening methods will be discussed in this paper: Highly accelerated life test (HALT), forward voltage drop tests for evaluating wire-bond integrity, burn-in options during or after highly accelerated stress test (HAST), and board-level qualification.

Plante, Jeannette↗
NASA NTRS2010

A Methodology to Assess the Impact of Optical and Electronic Crosstalk in a New Generation of Sensors Using Heritage Sensors

Electronic and optical crosstalk are radiometric challenges that often exist in the focal plane design in many sensors Such as MODIS. A methodology is described to assess the impact due to optical and electronic crosstalk on the measured radiance, and thereafter, the retrieval of geophysical products using MODIS Level I data sets. Based on a postulated set of electronic and optical crosstalk coefficients, and a set of MODIS scenes, we have simulated a system signal contamination on any detector on a focal plane when another detector on that focal plane is stimulated with a geophysical signal. The original MODIS scenes and the crosstalk impacted scenes can be used with validated geophysical algorithms to derive the final data products. Products contaminated with crosstalk are then compared to those without contamination to assess the impact magnitude and location, and will allow us to separate Out-Of-Band (OOB) leaks from hand-to-hand optical crosstalk, and identify potential failures to meet climate research requirements.

Oudrari, Hassan↗
NASA NTRS2011

Current and Future Parts Management at NASA

This presentation provides a high level view of current and future electronic parts management at NASA. It describes a current perspective of the new human space flight direction that NASA is beginning to take and how that could influence parts management in the future. It provides an overview of current NASA electronic parts policy and how that is implemented at the NASA flight Centers. It also describes some of the technical challenges that lie ahead and suggests approaches for their mitigation. These challenges include: advanced packaging, obsolescence and counterfeits, the global supply chain and Commercial Crew, a new direction by which NASA will utilize commercial launch vehicles to get astronauts to the International Space Station.

Sampson, Michael J.↗
NASA NTRS2017

IDEAS Pamphlet for CES

Pamphlet on the IDEAS project for the Game Changing Development programs NASA booth at the Consumer Electronics Show. Pamphlet covers a high level overview of the technology developed and its capabilities. The technology being developed for the Integrated Display and Environmental Awareness System (IDEAS) project is a wearable computer system with an optical heads-up display (HUD) providing various means of communication and data manipulation to the user. The wearable computer, in the form of smart glasses, would allow personnel to view and modify critical information on a transparent, interactive display. This is presented in their unobstructed field of view, without taking their eyes or hands away from their critical work. The product is being designed in a modular manner so that the user can adjust the capabilities of the device depending on need. IDEAS is a full featured hardware and softwaresystem built to enhance the capabilities of theNASA work force on the ground and in space.

Wearables↗
NASA NTRS2017

Performance of a Space-Based Wavelet Compressor for Plasma Count Data on the MMS Fast Plasma Investigation

Data compression has been a staple of imaging instruments for years. Recently, plasma measurements have utilized compression with relatively low compression ratios. The Fast Plasma Investigation (FPI) on board the Magnetospheric Multiscale (MMS) mission generates data roughly 100 times faster than previous plasma instruments, requiring a higher compression ratio to fit within the telemetry allocation. This study investigates the performance of a space-based compression standard employing a Discrete Wavelet Transform and a Bit Plane Encoder (DWT/BPE) in compressing FPI plasma count data. Data from the first 6 months of FPI operation are analyzed to explore the error modes evident in the data and how to adapt to them. While approximately half of the Dual Electron Spectrometer (DES) maps had some level of loss, it was found that there is little effect on the plasma moments and that errors present in individual sky maps are typically minor. The majority of Dual Ion Spectrometer burst sky maps compressed in a lossless fashion, with no error introduced during compression. Because of induced compression error, the size limit for DES burst images has been increased for Phase 1B. Additionally, it was found that the floating point compression mode yielded better results when images have significant compression error, leading to floating point mode being used for the fast survey mode of operation for Phase 1B. Despite the suggested tweaks, it was found that wavelet-based compression, and a DWT/BPE algorithm in particular, is highly suitable to data compression for plasma measurement instruments and can be recommended for future missions.

plasma↗
NASA NTRS2019

Indoor Ground Testing of a Small UAS Sense and Avoid Airborne Doppler Radar

The National Aeronautics and Space Administration’s Unmanned Aircraft System (UAS) Traffic Management (UTM) project is researching prototype technologies needed to ensure safe integration of UAS operations into the National Airspace System (NAS). Within the UTM Concept of Operations, UAS would be equipped with on-board Sense and Avoid (SAA) technology to continually monitor for manned and unmanned aircraft in its vicinity while operating beyond visual line of sight in uncontrolled airspace. To support this effort, a candidate commercially available 24.5 GHz Doppler radar was selected and evaluated to determine if the technology could reliably support minimum requirements for SAA applications of small UAS (sUAS). Indoor ground tests were conducted inside the NASA Langley Research Center’s Experimental Test Range (ETR) from a stationary platform to evaluate the Doppler radar performance characteristics and gain operational proficiency before the radar was authorized to transmit outdoors. A high speed linear rail system was developed for the radar evaluation and was shown to be an effective method to generate Doppler radar targets of known radar cross section. The accuracy of the range and velocity reported by the radar was shown to be dependent on the Kalman filter state variance parameter settings. Antenna measurements were collected with the radar installed both on and off a sUAS to quantify the relative antenna gain, beam width and side lobe levels of the radar’s Metamaterial Electronically Scanning Array (MESA) antennas at boresight and extreme field of view pointing vectors. The relative antenna gain measured 2.6 dB lower at extreme field view angles compared to the boresight radiation pattern.

Szatkowski, George N.↗