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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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At least 325 records · Page 18

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NASA NTRS1980

Cost reduction in space operations - Structuring a planetary program to minimize the annual funding requirement as opposed to minimizing the program runout cost

An approach is proposed for the structuring of a planetary mission set wherein the peak annual funding is minimized to meet the annual budget restraint. One aspect of the approach is to have a transportation capability that can launch a mission in any planetary opportunity; such capability can be provided by solar electric propulsion. Another cost reduction technique is to structure a mission test in a time sequenced fashion that could utilize essentially the same spacecraft for the implementation of several missions. A third technique would be to fulfill a scientific objective in several sequential missions rather than attempt to accomplish all of the objectives with one mission. The application of the approach is illustrated by an example involving the Solar Orbiter Dual Probe mission.

Herman, D. H.↗

NASA NTRS1983

Vehicle charging and potential on the STS-3 mission

An electron gun with fast pulse capability was used in the vehicle charging and potential experiment carried on the OSS-1 pallet to study dielectric charging, return current mechanisms, and the techniques required to manage the electrical charging of the orbiter. Return currents and charging of the dielectrics were measured during electron beam emission and plasma characteristics in the payload bay were determined in the absence of electron beam emission. The fast pulse electron generator, charge current probes, spherical retarding potential analyzer, and the digital control interface unit which comprise the experiment are described. Results show that the thrusters produce disturbances which are variable in character and magnitude. Strong ram/wake effects were seen in the ion densities in the bay. Vehicle potentials are variable with respect to the plasma and depend upon location on the vehicle relative to the main engine nozzles, the vehicle attitude, and the direction of the geomagnetic field.

Williamson, R.↗

NASA NTRS1984

On the Apollo subsatellite evidence for a lunar core

Two independent techniques used to infer the electrical conductivity of the interior of the Moon are discussed. The first is the measurement of an incident spectrum of electromagnetic waves in the solar wind near the Moon and the separate measurement of the incident plus reflected spectrum on the surface of the Moon. The second is the measurement of the distortion of the ambient magnetic field of the geomagnetic tail lobes by the conducting Moon. The size of the conducting region was found to be greater than 400 km in radius.

Russell, C. T.↗

NASA NTRS1986

Derivatives of the Arithmetic-Geometric Mean

Developed for theoretical studies of lightning requiring estimates of electric fields in clouds, the technique is expected to reduce computation time and improve accuracy.

Taton, F. B.↗

NASA NTRS1986

Experimental identification of electrostatic plasma waves within ion conic acceleration regions

The identification of electrostatic modes in the ionospheric and magnetospheric plasma is a difficult process. Some success has been achieved with electrostatic hydrogen cyclotron waves where Doppler broadening is insignificant and with zero-frequency turbulence where the spectrum is entirely Doppler shifted. However, it is not yet possible to identify specific modes in regions of transverse ion acceleration. If the modes are assumed to exist, some limits can be placed on their electric field amplitudes. An experimental technique to measure wavelength directly, thereby circumventing problems created by Doppler shifting, is reviewed.

Kintner, P. M.↗

NASA NTRS1988

Plasma acceleration, injection, and loss - Observational aspects

A history of the understanding of the sudden accelerations of charged particles noted in plasmas, and the accompanying intrusions of energized plasma into adjacent regions of space, is presented. It is pointed out that studies of the earth's magnetosphere are hampered by the lack of adequate sampling in space and time. Although the feature matching technique of building magnetic and electric field models can help compensate for the sparseness of experimental data, future studies will nonetheless require large numbers of spacecraft placed in carefully coordinated orbits. The notion that the ignition of portions of the auroral shell in association with earth flares results in the heating of ionospheric particles that are then convected inward to form the ring current is considered.

Mcilwain, C. E.↗

NASA NTRS1989

Robust high-performance control for robotic manipulators

Model-based and performance-based control techniques are combined for an electrical robotic control system. Thus, two distinct and separate design philosophies were merged into a single control system having a control law formulation including two distinct and separate components, each of which yields a respective signal componet that is combined into a total command signal for the system. Those two separate system components include a feedforward controller and feedback controller. The feedforward controller is model-based and contains any known part of the manipulator dynamics that can be used for on-line control to produce a nominal feedforward component of the system's control signal. The feedback controller is performance-based and consists of a simple adaptive PID controller which generates an adaptive control signal to complement the nomical feedforward signal.

Seraji, Homayoun↗

NASA NTRS1993

Micro-opto-mechanical devices and systems using epitaxial lift off

The integration of high quality, single crystal thin film gallium arsenide (GaAs) and indium phosphide (InP) based photonic and electronic materials and devices with host microstructures fabricated from materials such as silicon (Si), glass, and polymers will enable the fabrication of the next generation of micro-opto-mechanical systems (MOMS) and optoelectronic integrated circuits. Thin film semiconductor devices deposited onto arbitrary host substrates and structures create hybrid (more than one material) near-monolithic integrated systems which can be interconnected electrically using standard inexpensive microfabrication techniques such as vacuum metallization and photolithography. These integrated systems take advantage of the optical and electronic properties of compound semiconductor devices while still using host substrate materials such as silicon, polysilicon, glass and polymers in the microstructures. This type of materials optimization for specific tasks creates higher performance systems than those systems which must use trade-offs in device performance to integrate all of the function in a single material system. The low weight of these thin film devices also makes them attractive for integration with micromechanical devices which may have difficulty supporting and translating the full weight of a standard device. These thin film devices and integrated systems will be attractive for applications, however, only when the development of low cost, high yield fabrication and integration techniques makes their use economically feasible. In this paper, we discuss methods for alignment, selective deposition, and interconnection of thin film epitaxial GaAs and InP based devices onto host substrates and host microstructures.

Camperi-Ginestet, C.↗

NASA NTRS1994

Analysis of magnetic field levels at KSC

The scope of this work is to evaluate the magnetic field levels of distribution systems and other equipment at Kennedy Space Center (KSC). Magnetic fields levels in several operational areas and various facilities are investigated. Three dimensional mappings and contour are provided along with the measured data. Furthermore, the portion of magnetic fields generated by the 60 Hz fundamental frequency and the portion generated by harmonics are examined. Finally, possible mitigation techniques for attenuating fields from electric panels are discussed.

Christodoulou, Christos G.↗

NASA NTRS1994

Plasma Heating: An Advanced Technology

The Mercury and Apollo spacecraft shields were designed to protect astronauts from high friction temperatures (well over 2,000 degrees Fahrenheit) when re-entering the Earth's atmosphere. It was necessary to test and verify the heat shield materials on Earth before space flight. After exhaustive research and testing, NASA decided to use plasma heating as a heat source. This technique involves passing a strong electric current through a rarefied gas to create a plasma (ionized gas) that produces an intensely hot flame. Although NASA did not invent the concept, its work expanded the market for commercial plasma heating systems. One company, Plasma Technology Corporation (PTC), was founded by a member of the team that developed the Re-entry Heating Simulator at Ames Research Center (ARC). Dr. Camacho, President of PTC, believes the technology has significant environmental applications. These include toxic waste disposal, hydrocarbon, decomposition, medical waste disposal, asbestos waste destruction, and chemical and radioactive waste disposal.

Source record↗

NASA NTRS2003

The Chandra X-Ray Observatory Radiation Environment Model

CRMFLX (Chandra Radiation Model of ion FluX) is an environmental risk mitigation tool for use as a decision aid in planning the operations times for Chandra's Advanced CCD Imaging Spectrometer (ACIS) detector. The accurate prediction of the proton flux environment with energies of 100 - 200 keV is needed in order to protect the ACIS detector against proton degradation. Unfortunately, protons of this energy are abundant in the region of space Chandra must operate, and the on-board Electron, Proton, and Helium Instrument (EPHIN) does not measure proton flux levels of the required energy range. In addition to the concerns arising from the radiation belts, substorm injections of plasma from the magnetotail may increase the protons flux by orders of magnitude in this energy range. The Earth's magnetosphere is a dynamic entity, with the size and location of the magnetopause driven by the highly variable solar wind parameters (number density, velocity, and magnetic field components). Operational times for the telescope must be made weeks in advance, decisions which are complicated by the variability of the environment. CRMFLX is an engineering model developed to address these problems and provides proton flux and fluence statistics for the terrestrial outer magnetosphere, magnetosheath, and solar wind for use in scheduling ACIS operations. CRMFLX implements a number of standard models to predict the bow shock, magnetopause, and plasma sheet boundaries based on the sampling of historical solar wind data sets. Measurements from the GEOTAIL and POLAR spacecraft are used to create the proton flux database. This paper describes the recently released CRMFLX v2 implementation that includes an algorithm that propagates flux from an observation location to other regions of the magnetosphere based on convective ExB and VB-curvature particle drift motions in electric and magnetic fields. This technique has the advantage of more completely filling out the database and makes maximum use of limited data obtained during high Kp periods or in areas of the magnetosphere with poor satellite coverage.

Blackwell, W. C.↗

NASA NTRS1996

The delayed rectifier, IKI, is the major conductance in type I vestibular hair cells across vestibular end organs

Hair cells were dissociated from the semicircular canal, utricle, lagena and saccule of white king pigeons. Type I hair cells were identified morphologically based on the ratios of neck width to cuticular plate width (NPR < 0.72) as well as neck width to cell body width (NBR < 0.64). The perforated patch variant of the whole-cell recording technique was used to measure electrical properties from type I hair cells. In voltage-clamp, the membrane properties of all identified type I cells were dominated by a predominantly outward potassium current, previously characterized in semicircular canal as IKI. Zero-current potential, activation, deactivation, slope conductance, pharmacologic and steady-state properties of the complex currents were not statistically different between type I hair cells of different vestibular end organs. The voltage dependence causes a significant proportion of this conductance to be active about the cell's zero-current potential. The first report of the whole-cell activation kinetics of the conductance is presented, showing a voltage dependence that could be best fit by an equation for a single exponential. Results presented here are the first data from pigeon dissociated type I hair cells from utricle, saccule and lagena suggesting that the basolateral conductances of a morphologically identified population of type I hair cells are conserved between functionally different vestibular end organs; the major conductance being a delayed rectifier characterized previously in semicircular canal hair cells as IKI.

NASA Discipline Number 40-99↗

NASA NTRS1995

Design and Process Considerations for a Tunneling Tip Accelerometer

In this paper, we discuss issues related to the fabrication of a bulk micromachined single axis accelerometer. The accelerometer is designed to have a full scale range of ten millig and a sensitivity of tens of nanog. During the process, three distinctly different die are fabricated. These are subsequently assembled using an ally bonding technique. During the bonding operation, electrical contacts are made between layers. The accelerometer is controlled by electrostatic force plates above and below the proof mass. The lower electrode has a dual role. In operation, it provides a necessary control electrode. When not in operation, it is used to clamp the proof mass and prevents its motion. Results of the fabrication process and initial testing of the clamping function are reported.

tunneling tip accelerometer, accelerometer fabrica↗

NASA NTRS1991

Robust high-performance control for robotic manipulators

Model-based and performance-based control techniques are combined for an electrical robotic control system. Thus, two distinct and separate design philosophies have been merged into a single control system having a control law formulation including two distinct and separate components, each of which yields a respective signal component that is combined into a total command signal for the system. Those two separate system components include a feedforward controller and a feedback controller. The feedforward controller is model-based and contains any known part of the manipulator dynamics that can be used for on-line control to produce a nominal feedforward component of the system's control signal. The feedback controller is performance-based and consists of a simple adaptive PID controller which generates an adaptive control signal to complement the nominal feedforward signal.

Seraji, Homayoun↗

NASA NTRS2004

Split-resonator integrated-post MEMS gyroscope

A split-resonator integrated-post vibratory microgyroscope may be fabricated using micro electrical mechanical systems (MEMS) fabrication techniques. The microgyroscope may include two gyroscope sections bonded together, each gyroscope section including resonator petals, electrodes, and an integrated half post. The half posts are aligned and bonded to act as a single post.

Bae, Youngsam↗

NASA NTRS2014

Synthetic Biology and Microbial Fuel Cells: Towards Self-Sustaining Life Support Systems

NASA ARC and the J. Craig Venter Institute (JCVI) collaborated to investigate the development of advanced microbial fuels cells (MFCs) for biological wastewater treatment and electricity production (electrogenesis). Synthetic biology techniques and integrated hardware advances were investigated to increase system efficiency and robustness, with the intent of increasing power self-sufficiency and potential product formation from carbon dioxide. MFCs possess numerous advantages for space missions, including rapid processing, reduced biomass and effective removal of organics, nitrogen and phosphorus. Project efforts include developing space-based MFC concepts, integration analyses, increasing energy efficiency, and investigating novel bioelectrochemical system applications

bioelectrochemical systems↗

NASA NTRS2018

The Revolutionary Vertical Lift Technology (RVLT) Project

The Revolutionary Vertical Lift Technology (RVLT) Project is one of six projects in the Advanced Air Vehicles Program (AAVP) of the NASA Aeronautics Research Mission Directorate. The overarching goal of the RVLT Project is to develop and validate tools, technologies, and concepts to overcome key barriers for vertical lift vehicles. The project vision is to enable the next generation of vertical lift vehicles with aggressive goals for efficiency, noise, and emissions, to expand current capabilities and develop new commercial markets. The RVLT Project invests in technologies that support conventional, non-conventional, and emerging vertical-lift aircraft in the very light to heavy vehicle classes. Research areas include acoustic, aeromechanics, drive systems, engines, icing, hybrid-electric systems, impact dynamics, experimental techniques, computational methods, and conceptual design. The project research is executed at NASA Ames, Glenn, and Langley Research Centers; the research extensively leverages partnerships with the US Army, the Federal Aviation Administration, industry, and academia. The primary facilities used by the project for testing of vertical-lift technologies include the 14- by 22-Ft Wind Tunnel, Icing Research Tunnel, National Full-Scale Aerodynamics Complex, 7- by 10-Ft Wind Tunnel, Rotor Test Cell, Landing and Impact Research facility, Compressor Test Facility, Drive System Test Facilities, Transonic Turbine Blade Cascade Facility, Vertical Motion Simulator, Mobile Acoustic Facility, Exterior Effects Synthesis and Simulation Lab, and the NASA Advanced Supercomputing Complex. To learn more about the RVLT Project, please stop by booth #1004 or visit their website at https://www.nasa.gov/aeroresearch/programs/aavp/rvlt.

NASA↗

NASA NTRS2017

SiC Fibers and SiCf/SiC Ceramic Matrix Minicomposites Damage Behavior

Silicon Carbide based Ceramic Matrix Composites (CMCs) are attractive materials for use in high-temperature applications in the aerospace industry. Performance and durability of CMCs depend on the properties of its constituents such as fibers and matrix. Therefore, CMCs constituents limitations and damage mechanisms are discussed and characterized in representative simulated application conditions and dominant damage mechanisms are identified at elevated temperatures. In this work, the initiation and evolution of damage in Hi-Nicalon type S fiber-reinforced minicomposites with different interphases thicknesses from different manufacturers were investigated employing several nondestructive evaluation techniques such as acoustic emission, electrical resistance and microscopy. Moreover, the tensile creep behavior of single Hi-Nicalon Type S SiC fibers were tested and characterized and creep parameters were extracted. Fibers creep tests were performed in air or vacuum at 1200-1482 C under high stresses. Creep parameters was then used in understanding load sharing and lifing of ceramic matrix minicomposites. Future work plans will be reviewed.

SiC fibers↗