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NASA NTRS1981

Time delay and integration detectors using charge transfer devices

An imaging system comprises a multi-channel matrix array of CCD devices wherein a number of sensor cells (pixels) in each channel are subdivided and operated in discrete intercoupled groups of subarrays with a readout CCD shift register terminating each end of the channels. Clock voltages, applied to the subarrays, selectively cause charge signal flow in each subarray in either direction independent of the other subarrays. By selective application of four phase clock voltages, either one, two or all three of the sections subarray sections cause charge signal flow in one direction, while the remainder cause charge signal flow in the opposite direction. This creates a form of selective electronic exposure control which provides an effective variable time delay and integration of three, six or nine sensor cells or integration stages. The device is constructed on a semiconductor sustrate with a buried channel and is adapted for front surface imaging through transparent doped tin oxide gates.

Mccann, D. H.↗

NASA NTRS1988

Dendritic growth and structure of undercooled nickel base alloys

The principal objectives of this overall investigation are to: study means for obtaining high undercooling in levitation melted droplets, and study structures produced upon the solidification of these undercooled specimens. Thermal measurements are made of the undercooling, and of the rapid recalescence, to develop an understanding of the solidification mechanism. Comparison of results is made with the modeling studies. Characterization and metallographic work is done to gain an understanding of the relationship between rapid solidification variables and the structures so produced. In ground based work to date, solidification of undercooled Ni-25 wt percent Sn alloy was observed by high-speed cinematography and the results compared with optical temperature measurements. Also in ground based work, high-speed optical temperature measurements were made of the solidification behavior of levitated metal samples within a transparent glass medium. Two undercooled Ni-Sn alloys were examined. Measurements were carried out on samples at undercoolings up to 330 K. Microstructures of samples produced in ground based work were determined by optical metallography and by SEM, and microsegregation by electron microprobe measurements. A series of flight tests were planned to conduct experiments similar to the ground based experiments. The Space Shuttle Columbia carried an alloy undercooled experiment in the STS 61-C mission in January 1986. A sample of Ni-32.5 wt percent Sn eutectic was melted and solidified under microgravity conditions.

Flemings, M. C.↗

NASA NTRS2017

Update on NASA Microelectronics Activities

Mission Statement: The NASA Electronic Parts and Packaging (NEPP) Program provides NASA's leadership for developing and maintaining guidance for the screening, qualification, test. and usage of EEE parts by NASA as well as in collaboration with other government Agencies and industry. NASA Space Technology Mission Directorate (STMD) "STMD rapidly develops, demonstrates, and infuses revolutionary, high-payoff technologies through transparent, collaborative partnerships, expanding the boundaries of the aerospace enterprise." Mission Statement: The Space Environments Testing Management Office (SETMO) will identify, prioritize, and manage a select suite of Agency key capabilities/assets that are deemed to be essential to the future needs of NASA or the nation, including some capabilities that lack an adequate business base over the budget horizon. NESC mission is to perform value-added independent testing, analysis, and assessments of NASA's high-risk projects to ensure safety and mission success. NASA Space Environments and Avionics Fellows as well as Radiation and EEE Parts Community of Practice (CoP) leads.

NASA Electronic Parts and Packaging (NEPP)↗

NASA NTRS1980

Feasibility study consisting of a review of contour generation methods from stereograms

A review of techniques for obtaining contour information from stereo pairs is given. Photogrammetric principles including a description of stereoscopic vision are presented. The use of conventional contour generation methods, such as the photogrammetric plotting technique, electronic correlator, and digital correlator are described. Coherent optical techniques for contour generation are discussed and compared to the electronic correlator. The optical techniques are divided into two categories: (1) image plane operation and (2) frequency plane operation. The description of image plane correlators are further divided into three categories: (1) image to image correlator, (2) interferometric correlator, and (3) positive negative transparencies. The frequency plane correlators are divided into two categories: (1) correlation of Fourier transforms, and (2) filtering techniques.

Kim, C. J.↗

NASA NTRS2003

NASA Tech Briefs, July 2003

Topics covered include: Real-Time, High-Frequency QRS Electrocardiograph; Software for Improved Extraction of Data From Tape Storage; Radio System for Locating Emergency Workers; Software for Displaying High-Frequency Test Data; Capacitor-Chain Successive-Approximation ADC; Simpler Alternative to an Optimum FQPSK-B Viterbi Receiver; Multilayer Patch Antenna Surrounded by a Metallic Wall; Software To Secure Distributed Propulsion Simulations; Explicit Pore Pressure Material Model in Carbon-Cloth Phenolic; Meshed-Pumpkin Super-Pressure Balloon Design; Corrosion Inhibitors as Penetrant Dyes for Radiography; Transparent Metal-Salt-Filled Polymeric Radiation Shields; Lightweight Energy Absorbers for Blast Containers; Brush-Wheel Samplers for Planetary Exploration; Dry Process for Making Polyimide/ Carbon-and-Boron-Fiber Tape; Relatively Inexpensive Rapid Prototyping of Small Parts; Magnetic Field Would Reduce Electron Backstreaming in Ion Thrusters; Alternative Electrochemical Systems for Ozonation of Water; Interferometer for Measuring Displacement to Within 20 pm; UV-Enhanced IR Raman System for Identifying Biohazards; Prognostics Methodology for Complex Systems; Algorithms for Haptic Rendering of 3D Objects; Modeling and Control of Aerothermoelastic Effects; Processing Digital Imagery to Enhance Perceptions of Realism; Analysis of Designs of Space Laboratories; Shields for Enhanced Protection Against High-Speed Debris; Study of Dislocation-Ordered In(x)Ga(1-x)As/GaAs Quantum Dots; and Tilt-Sensitivity Analysis for Space Telescopes.

Source record↗

NASA NTRS2006

Electrically Conductive Anodized Aluminum Surfaces

Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to < or = 10(exp 9) Omega-cm. The present treatment does this. The treatment is a direct electrodeposition process in which the outer anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In comparison with these competing finishes, the present nanocomposite finishes are expected to cost 50 to 20 percent less and to last longer.

Nguyen, Trung Hung↗

NASA NTRS1992

Beneficiation of ilmenite from lumar analog

The results reported were obtained on a meteoric eucrite sample called Millbillillie Sample no. 173. Optical microscopy studies of the sample showed it to consist of ilmenite, troilite, and transparent gangue. The transparent gangue consisted of feldspar (anorthite), pyroxenes, olivines, and opaques. Troilite was present in minor quantities. Screen assay analyses of the 30, 100, 200, and 400 US mesh screen fractions showed that minor concentration of titanium occurred in the 200 x 400 and -400 mesh screen fractions. Scanning electron microscopy (SEM) studies of the bulk sample showed the presence of a variety of ilmenite grains, ranging from 50 microns down to less than 1 micron without any evidence of liberation. Electron Diffraction Scans (EDS) confirmed the ratio of Fe to Ti in the ilmenite grains. Dry magnetic separation in a Frantz Isodynamic Separator was found to be effective only at sizes finer than 150 microns (100 US mesh) and more so at 200 mesh (74 microns). In each case, dedusting of the sample to remove -400 mesh (-0.037 microns) fines was required. Liberation size was determined to be 200 mesh and finer. The highest grade concentrate assaying 3.45 percent Ti was produced by magnetic separation of the -200 + 400 mesh screen fraction assaying 0.44 Ti (from a -30 mesh sample) at a current setting of 0.35 AMP. This concentrate contained 21.2 percent of the Ti values in the screen fraction with 2.72 weight percent of feed to test. The results can be projected to a sample stage ground to -200 mesh. Magnetic separation of the 200 + 400 mesh (-0.074 + 0.037 microns) should produce a concentrate accounting for 1.41 weight percent of the feed. This concentrate will analyze 3.45 percent Ti and contain 10.3 percent of the Ti values in the feed. By changing the Frantz Magnetic Separator settings, a lower grade concentrate analyzing 0.98 percent Ti can be produced at an increased recovery of 25.4 percent. The concentrate weight will be 11.7 percent of the feed. It must be emphasized that improved grades and recoveries can be obtained with the -400 mesh fines. However, beneficiation of these extremely fine materials is not possible in a practical process scheme.

Ramadorai, G.↗

NASA NTRS1971

Optical transmittance of fused silica during irradiation processes.

The level of irradiation-induced optical absorption and the resulting heat deposition in the transparent fused-silica wall of a nuclear light bulb engine during normal operation are investigated by means of a series of related experiments using available radiation sources, each of which simulates some aspect of the radiation flux or dose of the engine. A comparison of the results obtained in electron and reactor experiments indicates that the generation of optical absorption is due to ionizing effects and that neutron-caused displacement effects do not contribute significantly to optical absorption. The implications of these and other results obtained are discussed.

Palma, G. E.↗

NASA NTRS2018

Human Automation Teaming: Lessons Learned and Future Directions

Full autonomy seems to be the goal for system developers in almost every area of the economy. However, as we move from automated systems to autonomous systems, designers have needed to insert humans to oversee automation that has traditionally been brittle or incomplete. This creates its own problems as the operator is usually out of the loop when the automation hands over problems that it cannot handle. To better handle these situations, it has been proposed that we develop human automation teams that have shared goals and objectives to support task performance. This paper will describe an initial model of Human Automation Teaming (HAT) which has three elements: transparency, bi-directional communications, and human-directed execution. Transparency in our model is a method for giving insight into the reasoning behind automated recommendations and actions, bi-directional communication allows the operator to communicate directly with the automation, and finally the automation defers execution to the human. The model was implemented through a number of features on an electronic flight bag (EFB) which are described in the paper. The EFB was installed in a mid-fidelity flight simulator and used by 12 airline pilots to support diversion decisions during off-nominal flight scenarios. Pilots reported that working with the HAT automation made diversion decisions easier and reduced their workload. They also reported that the information provided about diversion airports was similar to what they would receive from ground dispatch, thus making coordination with dispatch easier and less time consuming. These HAT features engender more trust in the automation when appropriate, and less when not, allowing improved supervision of automated functions by flight crews.

Human-Autonomy Teaming↗

NASA NTRS1985

A summary report on the Flat-Plate Solar Array Project Workshop on Transparent Conducting Polymers

The proceedings and technical discussions of a workshop on Transparent Conducting Polymers (TCP) for solar cell applications are reported. This is in support of the Device Research Task of the Flat-Flate Solar Array Project. The workshop took place on January 11 and 12, 1985, in Santa Barbara, California. Participants included university and industry researchers. The discussions focused on the electronic and optical properties of TCP, and on experimental issues and problems that should be addressed for high-efficiency solar cell application.

Kachare, R.↗

NASA NTRS1991

Experiment and theoretical study of the propagation of high power microwave pulse in air breakdown environment

In the study of the propagation of high power microwave pulse, one of the main concerns is how to minimize the energy loss of the pulse before reaching the destination. In the very high power region, one has to prevent the cutoff reflection caused by the excessive ionization in the background air. A frequency auto-conversion process which can lead to reflectionless propagation of powerful EM pulses in self-generated plasmas is studied. The theory shows that under the proper conditions the carrier frequency, omega, of the pulse will indeed shift upward with the growth of plasma frequency, omega(sub pe). Thus, the plasma during breakdown will always remain transparent to the pulse (i.e., omega greater than omega(sub pe)). A chamber experiment to demonstrate the frequency auto-conversion during the pulse propagation through the self-generated plasma is then conducted in a chamber. The detected frequency shift is compared with the theoretical result calculated y using the measured electron density distribution along the propagation path of the pulse. Good agreement between the theory and the experiment results is obtained.

Kuo, S. P.↗

NASA NTRS1992

Integration and use of Microgravity Research Facility: Lessons learned by the crystals by vapor transport experiment and Space Experiments Facility programs

The Crystals by Vapor Transport Experiment (CVTE) and Space Experiments Facility (SEF) are materials processing facilities designed and built for use on the Space Shuttle mid deck. The CVTE was built as a commercial facility owned by the Boeing Company. The SEF was built under contract to the UAH Center for Commercial Development of Space (CCDS). Both facilities include up to three furnaces capable of reaching 850 C minimum, stand-alone electronics and software, and independent cooling control. In addition, the CVTE includes a dedicated stowage locker for cameras, a laptop computer, and other ancillary equipment. Both systems are designed to fly in a Middeck Accommodations Rack (MAR), though the SEF is currently being integrated into a Spacehab rack. The CVTE hardware includes two transparent furnaces capable of achieving temperatures in the 850 to 870 C range. The transparent feature allows scientists/astronauts to directly observe and affect crystal growth both on the ground and in space. Cameras mounted to the rack provide photodocumentation of the crystal growth. The basic design of the furnace allows for modification to accommodate techniques other than vapor crystal growth. Early in the CVTE program, the decision was made to assign a principal scientist to develop the experiment plan, affect the hardware/software design, run the ground and flight research effort, and interface with the scientific community. The principal scientist is responsible to the program manager and is a critical member of the engineering development team. As a result of this decision, the hardware/experiment requirements were established in such a way as to balance the engineering and science demands on the equipment. Program schedules for hardware development, experiment definition and material selection, flight operations development and crew training, both ground support and astronauts, were all planned and carried out with the understanding that the success of the program science was as important as the hardware functionality. How the CVTE payload was designed and what it is capable of, the philosophy of including the scientists in design and operations decisions, and the lessons learned during the integration process are descussed.

Heizer, Barbara L.↗

NASA NTRS1988

Soluble and colorless polyimides

Results are reported in the form of reaction diagrams, graphs, and tables of research being conducted to synthesize and characterize linear aromatic polyimides which are soluble in common organic solvents and optically transparent in the 400-600 nm spectral range. These flexible and high-temperature polymeric films and coatings are needed for specific applications on space components such as antennas, solar cells, and thermal control coating systems. Several series of these polyimide films have been produced by making variations in the polymer molecular structure aimed at reducing the electronic interactions between the polymer chains.

St. Clair, Anne K.↗

NASA NTRS2007

Optically Transparent Split-Ring Antennas for 1 to 10 GHz

Split-ring antennas made from optically transparent, electrically conductive films have been invented for applications in which there are requirements for compact antennas capable of operation over much or all of the frequency band from 1 to 10 GHz. Primary examples of such applications include wireless local-area networks and industrial, scientific, and medical (ISM) applications. These antennas can be conveniently located on such surfaces as those of automobile windows and display screens of diverse hand-held electronic units. They are fabricated by conventional printed-circuit techniques and can easily be integrated with solid-state amplifier circuits to enhance gain. The structure of an antenna of this type includes an antenna/feed layer supported on the top or outer face of a dielectric (e.g., glass) and, optionally, a ground layer on the bottom or inner face of the substrate. The ring can be in the form of either a conductive strip or a slot in the antenna/feed layer. The ring can be of rectangular, square, circular, elliptical, or other suitable shape and can be excited by means of a microstrip, slot line, or coplanar waveguide. For example, the antenna shown in the figure features a square conductive-strip split ring with a microstrip feed. In general, an antenna fed at its external boundary in the manner of this invention presents very high impedance, thereby creating an impedance-matching problem. Splitting the ring . that is, cutting a notch through the ring . offers a solution to the problem in that the notch fixes the location of maximum electric field, which location is directly related to the impedance. Thus, an excellent impedance match can be achieved through proper choice of the location of the notch. In geometric layout, such a ring antenna structure is typically between 1.4 and 1.3 the size of a patch antenna capable of operating in the same frequency range. This miniaturization of the antenna is desirable, not only because it contributes to overall miniaturization of equipment, but also because minimization of the extent of the optically transparent, electrically conductive film helps to minimize the electrical loss associated with the surface resistance ( 5 ohms per square) of the transparent, electrically conductive film material. Incidentally, even at 5 ohms per square, this surface resistance is significantly less than that of indium tin oxide film (typically > 25 ohms per square), which, heretofore has been the transparent, electrically conductive film material of choice. At the time of writing this article, information on the composition of the lower-resistance film used in the antennas of this invention was not available.

Lee, Richard Q.↗

NASA NTRS1996

Transparent, Conductive Coatings Developed for Arc-Proof Solar Arrays

Transparent, conductive thin-film coatings have many potential applications where a surface must be able to dissipate electrical charges without sacrificing its optical properties. Such applications include automotive and aircraft windows, heat mirrors, optoelectronic devices, gas sensors, and solar cell array surfaces for space applications. Many spacecraft missions require that solar cell array surfaces dissipate charges in order to avoid damage such as electronic upsets, formation of pinholes in the protective coatings on solar array blankets, and contamination due to deposition of sputtered products. In tests at the NASA Lewis Research Center, mixed thin-films of sputter-deposited indium tin oxide (ITO) and magnesium fluoride (MgF2) that could be tailored to the desired sheet resistivity, showed transmittance values of greater than 90 percent. The samples evaluated were composed of mixed, thin-film ITO/MgF2 coatings, with a nominal thickness of 650 angstroms, deposited onto glass substrates. Preliminary results indicated that these coatings were durable to vacuum ultraviolet radiation and atomic oxygen. These coatings show promise for use on solar array surfaces in polar low-Earth-orbit environments, where a sheet resistivity of less than 10(exp 8)/square is required, and in geosynchronous orbit environments, where a resistivity of less than 10(exp 9)/square is required.

Source record↗

NASA NTRSDate not supplied

Toward High-Endurance Nonvolatile Reconfigurable Metasurfaces

The applications of adaptive optics extend across multiple sectors, encompassing areas such as LiDAR, biological and chemical sensing, and free-space optical communications. The advent of metasurfaces optics with reconfigurability has offered a versatile platform for the design of compact optical components, offering a compelling alternative to their conventional bulky counterparts. In this study, we introduce the PROWESS (Phase change Reconfigurable Optical WavEfront Synthesis System project at NASA LaRC), electrically reconfigurable metasurfaces using low-loss, high-contrast phase change material (PCM), Ge2Sb2Se4Te integrated with IR-transparent silicon microheater for various practical applications. The talk covers a reliable platform for switching large-scale PCM-based devices utilizing a microheater and an architecture for the metasurface switching within an integrated circuit configuration, which is compatible with standard foundry fabrication processes. The utilization of near- to midinfrared transparent silicon microheater in the proposed architecture opens possibilities for the development of reconfigurable transmissive optics such as filters, zoom lenses, and beam steering modules. We demonstrated switching of 140 µm × 140 µm PCM pixel, on a 200 µm × 200 µm silicon microheater for several thousand cycles. Further, we performed an in-depth investigation into the failure mechanism utilizing techniques such as transmission electron microscopy and thermal modeling. Guidelines for device performance improvement are proposed, and an improved design with larger endurance is shown in progress. With further progress, we aim to unlock the full potential of PCM-based devices and advance the field of adaptive optics with demonstrable examples including a reconfigurable beam steerer for ocean surface flash LiDAR and Navigation Doppler LiDAR for precise lunar landing missions.

metasurface optics↗

NASA NTRS1986

Effect of hard particle impacts on the atomic oxygen survivability of reflector surfaces with transparent protective overcoats

Silver mirror samples with protective coatings were subjected to a stream of 27 microns alumina particles to induce pinhole defects. The protective coating consisted of a layer of aluminum dioxide over silver followed by a layer of silicon dioxide over the alumina. Samples were prepared on both graphite-epoxy composite and fused quartz substrates. After exposure to the hard particle stream, the samples were exposed to an oxygen plasma environment in a laboratory plasma asher. The effects of both the hard particles and the oxygen plasma were documented by both reflectance measurements and scanning electron microscopy. The results indicated that oxidative damage to the silver reflecting layer continues beyond that of the erosively exposed silver. Oxidative undercutting of the silver layer and graphite-epoxy substrate continues in undamaged areas through adjacent, particle damaged defect sites. This may have implications for the use of such mirrors in a space station solar dynamic power system.

Gulino, D. A.↗

NASA NTRS1987

Effect of hard particle impacts on the atomic oxygen survivability of reflector surfaces with transparent protective overcoats

Gulino, Daniel A.↗