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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 865 records · Page 48

All sources NASA NTRS DOE OSTI

NASA NTRS2001

An Approach to Establishing System Benefits for Technology in NASA's Hypersonics Investment Area

Hueter, Uwe↗

NASA NTRS2016

Trade-Space Analysis Tool for Constellations (TAT-C)

Traditionally, space missions have relied on relatively large and monolithic satellites, but in the past few years, under a changing technological and economic environment, including instrument and spacecraft miniaturization, scalable launchers, secondary launches as well as hosted payloads, there is growing interest in implementing future NASA missions as Distributed Spacecraft Missions (DSM). The objective of our project is to provide a framework that facilitates DSM Pre-Phase A investigations and optimizes DSM designs with respect to a-priori Science goals. In this first version of our Trade-space Analysis Tool for Constellations (TAT-C), we are investigating questions such as: How many spacecraft should be included in the constellation? Which design has the best costrisk value? The main goals of TAT-C are to: Handle multiple spacecraft sharing a mission objective, from SmallSats up through flagships, Explore the variables trade space for pre-defined science, cost and risk goals, and pre-defined metrics Optimize cost and performance across multiple instruments and platforms vs. one at a time.This paper describes the overall architecture of TAT-C including: a User Interface (UI) interacting with multiple users - scientists, missions designers or program managers; an Executive Driver gathering requirements from UI, then formulating Trade-space Search Requests for the Trade-space Search Iterator first with inputs from the Knowledge Base, then, in collaboration with the Orbit Coverage, Reduction Metrics, and Cost Risk modules, generating multiple potential architectures and their associated characteristics. TAT-C leverages the use of the Goddard Mission Analysis Tool (GMAT) to compute coverage and ancillary data, streamlining the computations by modeling orbits in a way that balances accuracy and performance.TAT-C current version includes uniform Walker constellations as well as Ad-Hoc constellations, and its cost model represents an aggregate model consisting of Cost Estimating Relationships (CERs) from widely accepted models. The Knowledge Base supports both analysis and exploration, and the current GUI prototype automatically generates graphics representing metrics such as average revisit time or coverage as a function of cost.

Science Data Processing↗

NASA NTRS2018

MagicDraw Report Generation for the Resource Prospector Payload

Magic Draw is a tool currently being used by System Engineers to design model-based representations of the Resource Prospector (RP) Payload. Often, reports are needed to display and communicate the information and schematics within the MagicDraw model. Since constant changes are being made to the model, these reports also need to be maintained with each change. Because this is tedious and time consuming, I was assigned to implement MagicDraw Report Wizard Templates using Velocity Template Language (VTL) scripts. These report template scripts pull specific images, data, and elements directly from the MagicDraw model, allowing the user to have a report that is updated with the current state of the model upon its generation.

MagicDraw↗

NASA NTRS1985

The interaction of a dipolar thunderstorm with its global electrical environment

The role of the thundercloud in the global electric circuit has been considered by many researchers. Thus, Holzer and Saxon (1952) have constructed a simple model of a bipolar thunderstorm. The global models considered provide insight into the atmospheric electric circuit but are restricted, both by various analytical mathematical representations and by computer size, to a grid of about five degrees in latitude and longitude. A need exists, therefore, for the development of a numerical regional model capable of resolving small-scale phenomena so that their coupling into the global-scale circuit can be examined. The construction of a two-dimensional quasi-static numerical model of atmospheric electricity is discussed. The model provides a basis for the calculation of the global electric field and current distribution produced by a single thunderstorm generator. In connection with the calculations, the thunderstorm was defined by a quasi-static current source function which generates a dipole charge configuration.

Tzur, I.↗

NASA NTRS2001

An Approach to Establishing System Benefits for Technologies In NASA's Spaceliner Investment Area

NASA's has established long term goals for access-to-space. The third generation launch systems are to be fully reusable and operational around 2025. The goals for the third generation launch system are to significantly reduce cost and improve safety over current systems. The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center in Huntsville, AL has the agency lead to develop space transportation technologies. Within ASTP, under the Spaceliner Investment Area, third generation technologies are being pursued. The Spaceliner Investment Area's primary objective is to mature vehicle technologies to enable substantial increases in the design and operating margins of third generation RLVs (current Space Shuttle is considered the first generation RLV) by incorporating advanced propulsion systems, materials, structures, thermal protection systems, power, and avionics technologies. Advancements in design tools and better characterization of the operational environment will result in reduced design and operational variabilities leading to improvements in margins. Improvements in operational efficiencies will be obtained through the introduction of integrated vehicle health management, operations and range technologies. Investments in these technologies will enable the reduction in the high operational costs associated with today's vehicles by allowing components to operate well below their design points resulting in improved component operating life, reliability, and safety which in turn reduces both maintenance and refurbishment costs. The introduction of advanced technologies may enable horizontal takeoff by significantly reducing the takeoff weight and allowing use of existing infrastructure. This would be a major step toward the goal of airline-like operation. These factors in conjunction with increased flight rates, resulting from reductions in transportation costs, will result in significant improvements of future vehicles. The real-world problem is that resources are limited and technologies need to be prioritized to assure the resources are spent on technologies that provide the highest system level benefits. Toward that end, a systems approach is being taken to determine the benefits of technologies for the Spaceliner Investment Area. Technologies identified to be enabling will be funded. However, the other technologies will be funded based on their system's benefits. Since the final launch system concept will not be decided for many years, several vehicle concepts are being evaluated to determine technology benefits. Not only performance, but also cost and operability are being assessed. This will become an annual process to assess these technologies against their goals and the benefits to various launch systems concepts. The paper describes the system process, tools and concepts used to determine the technology benefits. Preliminary results will be presented along with the current technology investments that are being made by ASTP's Spaceliner Investment Area.

Hueter, Uwe↗

NASA NTRS1971

Ion-wave current instabilities and anomalous resistivity.

A theory of ion-wave current instabilities which takes into account, in a self-consistent manner, the inhomogeneities generated by field-aligned currents in a collisionless plasma is presented. Diamagnetic current associated with the current-produced density gradient is included in the distribution. The theory predicts that for a given frequency, the current threshold for ion-wave current instabilities is, in general, much below the threshold of ion acoustic instability in a uniform plasma as given by Fried and Gould. The current threshold is essentially zero in the limit when the ion Landau damping effect is negligible, or equivalently, the ion-wave current instabilities are absolute if there are no limitations on the wavelength. This is true even in the absence of externally applied density gradients in contrast to Kadomtsev's drift-wave results. For dimensions of interest in laboratory plasmas, the predicted linear growth rate increases with increasing longitudinal wavelength and with decreasing wavelength parallel to the diamagnetic current. Under the conditions of an experiment on anomalous resistivity (the dimensions but not the geometry of the machine have been considered), there is good agreement between the predicted onset of ion-wave current instabilities and the experimental data on the onset of anomalous resistivity.

Kan, J. R.↗

NASA NTRS1980

A modeling of magnetic field variations during magnetospheric substorms

Magnetic field variations in the noon-midnight plane during the magnetospheric substorm are studied in terms of changes of three current systems: the dynamo-driven current on the magnetopause, the cross-tail current and the field-aligned current-auroral electrojet system. The field-aligned current is assumed to be generated as a result of interruption and subsequent diversion of the cross-tail current to the ionosphere. It is concluded that the available observations are consistent with a large increase of the three currents.

Akasofu, S.-I.↗

NASA NTRS1962

The Analysis of a Vortex Type Magnetohydrodynamic Induction Generator

Consideration it is given to the performance to the characteristics of an AC magnetohydrodynamic power generator, A rotating magnetic field is imposed on the vortex flow of an electrically conducting fluid, which is injected tangentially into an annulus formed by two nonconducting concentric cylinders and two nonconducting end plates. A perturbation technique is used to determine the two dimensional velocity and three dimensional electromagnetic field and current distributions. Finally, the generated power, the ohmic losses, the effective power and the electrical efficiency of the converter system are calculated.

MAGNETOHYDRODYNAMIC GENERATOR↗

NASA NTRS2009

Manipulating Neutral Atoms in Chip-Based Magnetic Traps

Several techniques for manipulating neutral atoms (more precisely, ultracold clouds of neutral atoms) in chip-based magnetic traps and atomic waveguides have been demonstrated. Such traps and waveguides are promising components of future quantum sensors that would offer sensitivities much greater than those of conventional sensors. Potential applications include gyroscopy and basic research in physical phenomena that involve gravitational and/or electromagnetic fields. The developed techniques make it possible to control atoms with greater versatility and dexterity than were previously possible and, hence, can be expected to contribute to the value of chip-based magnetic traps and atomic waveguides. The basic principle of these techniques is to control gradient magnetic fields with suitable timing so as to alter a trap to exert position-, velocity-, and/or time-dependent forces on atoms in the trap to obtain desired effects. The trap magnetic fields are generated by controlled electric currents flowing in both macroscopic off-chip electromagnet coils and microscopic wires on the surface of the chip. The methods are best explained in terms of examples. Rather than simply allowing atoms to expand freely into an atomic waveguide, one can give them a controllable push by switching on an externally generated or a chip-based gradient magnetic field. This push can increase the speed of the atoms, typically from about 5 to about 20 cm/s. Applying a non-linear magnetic-field gradient exerts different forces on atoms in different positions a phenomenon that one can exploit by introducing a delay between releasing atoms into the waveguide and turning on the magnetic field.

Aveline, David↗

NASA NTRS1985

Examination of the Circle Spline Routine

The Circle Spline routine is currently being used for generating both two and three dimensional spline curves. It was developed for use in ESCHER, a mesh generating routine written to provide a computationally simple and efficient method for building meshes along curved surfaces. Circle Spline is a parametric linear blending spline. Because many computerized machining operations involve circular shapes, the Circle Spline is well suited for both the design and manufacturing processes and shows promise as an alternative to the spline methods currently supported by the Initial Graphics Specification (IGES).

Dolin, R. M.↗

NASA NTRS2018

LUVOIR Primary Mirror Segment Alignment Control With Joint Laser Metrology and Segment Edge Sensing

An approach is developed for the alignment and stability maintenance of the LUVOIR segmented primary mirror using a segment state estimation and wavefront control method based on a hybrid segment motion sensing architecture of laser truss metrology and segment edge sensors. Our current computer model was generated for LUVOIR Architecture Option A with a 15-meter aperture, 120segment primary mirror. The methodology and simulation results will be presented and analyzed. JPL has a long history of technology development in laser metrology and edge sensors, including work in SIM [7], Keck and TMT [8], CCAT [3] and LUVOIR [1]. We will discuss our current efforts of LUVOIR laser metrology and edge-sensor models development, showing sensitivities of sensor measurements to various mirror eigenmodes, removing global modes and strengthening weak modes by performing joint (hybrid) laser-metrology and edge sensing. We will define and derive an important performance metric called wavefront error multiplier (WEM), and show that WEM provides a simple link between sensor errors and the closed-loop (controlled) system wavefront error. We will show WEM values for several hybrid sensor configuration options studied. We will discuss an algorithm for mirror shape control and maintenance through segment state and wavefront estimations using joint edge-metrology sensing. We will compare simulated performance of mirror state estimation, wavefront estimation and wavefront control based on joint edge-metrology sensing among several sensor configurations, and show the impact of sensor error distributions on the segmented mirror alignment performance. Mirror shape control performance will be also be evaluated in terms of imaging contrast between inner working angles (IWA) and outer working angles (OWA) of a LUVOIR coronagraph. The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. LUVOIR is a mission concept under study for the next astronomy Decadal Survey—the information presented in this paper is pre-decisional and is provided for planning and discussion purposes only.

Shelton, Chris↗

NASA NTRS2006

A highly capable arbitrary waveform generator for next generation radar systems

We are developing an Arbitrary Waveform Generator (AWG) to provide enhanced capability for radar applications. The current design will accommodate two waveform generators on a single unit for dual frequency operation. The basic architecture of this unit employs a Field Programmable Gate Array (FPGA) and a high speed and high precision Digital to Analog Converter (DAC) for direct digital synthesis. This AWG will be capable of up to 450 MHz bandwidth with ability for frequency notching. Phase fidelity of less than 1.2(sup o) deviation RMS is also achievable. This AWG operates with lower power consumption as compared with other waveform generators, which is advantageous for future spaceborne applications. This will enable radars to return higher precision data, to be reduced in complexity, and to operate in any band without interfering with dedicated bandwidths.

chirp generators↗

NASA NTRS2009

Next Generation Advanced Video Guidance Sensor Development and Test

The Advanced Video Guidance Sensor (AVGS) was the primary docking sensor for the Orbital Express mission. The sensor performed extremely well during the mission, and the technology has been proven on orbit in other flights too. Parts obsolescence issues prevented the construction of more AVGS units, so the next generation of sensor was designed with current parts and updated to support future programs. The Next Generation Advanced Video Guidance Sensor (NGAVGS) has been tested as a breadboard, two different brassboard units, and a prototype. The testing revealed further improvements that could be made and demonstrated capability beyond that ever demonstrated by the sensor on orbit. This paper presents some of the sensor history, parts obsolescence issues, radiation concerns, and software improvements to the NGAVGS. In addition, some of the testing and test results are presented. The NGAVGS has shown that it will meet the general requirements for any space proximity operations or docking need.

Howard, Richard T.↗

NASA NTRS2013

Properties and Performance Attributes of Novel Co-extruded Polyolefin Battery Separator Materials: Electrical Properties - Part 2

As NASA prepares for its next era of manned spaceflight missions, advanced energy storage technologies are being developed and evaluated to address and enhance future mission needs and technical requirements. Cell-level components for advanced lithium-ion batteries possessing higher energy, more reliable performance and enhanced, inherent safety characteristics have been under development within the NASA infrastructure. A key component for safe and reliable cell performance is the cell separator, which separates the two energetic electrodes and functions to inhibit the occurrence of an internal short circuit but preserves an ionic current. Recently, a new generation of co-extruded separator films has been developed by ExxonMobil Chemical and introduced into their battery separator product portfolio. Several grades of this new separator material were evaluated with respect to dynamic mechanical properties and safety-related performance attributes, and the results of these evaluations were previously reported in "Part 1: Mechanical Properties" of this publication. This current paper presents safety-related performance results for these novel materials obtained by employing a complementary experimental methodology, which involved the analysis of separator impedance characteristics as a function of temperature. The experimental results from this study are discussed with respect to potential cell safety enhancement for future aerospace as well as for terrestrial energy storage needs, and they are compared with pertinent mechanical properties of these materials, as well as with current state-of-the practice separator materials.

Baldwin, Richard S.↗

NASA NTRS2008

High-Voltage, Asymmetric-Waveform Generator

The shapes of waveforms generated by commercially available analytical separation devices, such as some types of mass spectrometers and differential mobility spectrometers are, in general, inadequate and result in resolution degradation in output spectra. A waveform generator was designed that would be able to circumvent these shortcomings. It is capable of generating an asymmetric waveform, having a peak amplitude as large as 2 kV and frequency of several megahertz, which can be applied to a capacitive load. In the original intended application, the capacitive load would consist of the drift plates in a differential-mobility spectrometer. The main advantage to be gained by developing the proposed generator is that the shape of the waveform is made nearly optimum for various analytical devices requiring asymmetric-waveform such as differential-mobility spectrometers. In addition, this waveform generator could easily be adjusted to modify the waveform in accordance with changed operational requirements for differential-mobility spectrometers. The capacitive nature of the load is an important consideration in the design of the proposed waveform generator. For example, the design provision for shaping the output waveform is based partly on the principle that (1) the potential (V) on a capacitor is given by V=q/C, where C is the capacitance and q is the charge stored in the capacitor; and, hence (2) the rate of increase or decrease of the potential is similarly proportional to the charging or discharging current. The proposed waveform generator would comprise four functional blocks: a sine-wave generator, a buffer, a voltage shifter, and a high-voltage switch (see Figure 1). The sine-wave generator would include a pair of operational amplifiers in a feedback configuration, the parameters of which would be chosen to obtain a sinusoidal timing signal of the desired frequency. The buffer would introduce a slight delay (approximately equal to 20 ns) but would otherwise leave the fundamental timing signal unchanged. The buffered timing signal would be fed as input to the level shifter. The output of the level shifter would serve as a timing and control signal for the high-voltage switch, causing the switch to alternately be (1) opened, allowing the capacitive load to be charged from a high-voltage DC power supply; then (2) closed to discharge the capacitive load to ground. Hence, the output waveform would closely approximate a series of exponential charging and discharging curves (see Figure 2).

Beegle, Luther W.↗

NASA NTRS2010

Poynting Robertson Battery and the Chiral Magnetic Fields of AGN Jets

We propose that the magnetic fields in the accretion disks of active galactic nuclei (AGNs) are generated by azimuthal electric currents due to the difference between the plasma electron and ion velocities that arises when the electrons are retarded by interactions with the AGN photons (the Poynting Robertson battery). This process provides a unique relation between the polarity of the poloidal B field to the angular velocity Omega of the accretion disk (B is parallel to Omega), a relation absent in the more popular dynamo B-field generation. This then leads to a unique direction for the toroidal B field induced by disk rotation. Observations of the toroidal fields of 29 AGN jets revealed by parsec-scale Faraday rotation measurements show a clear asymmetry that is consistent with this model, with the probability that this asymmetry comes about by chance being approx.0.06 %. This lends support to the hypothesis that the universe is seeded by B fields that are generated in AGNs via this mechanism and subsequently injected into intergalactic space by the jet outflows.

Kazanas, Demosthenes↗

NASA NTRS1995

The JPL Mars gravity field, Mars50c, based upon Viking and Mariner 9 Doppler tracking data

This report summarizes the current JPL efforts of generating a Mars gravity field from Viking 1 and 2 and Mariner 9 Doppler tracking data. The Mars 50c solution is a complete gravity field to degree and order 50 with solutions as well for the gravitational mass of Mars, Phobos, and Deimos. The constants and models used to obtain the solution are given and the method for determining the gravity field is presented. The gravity field is compared to the best current gravity GMM1 of Goddard Space Flight Center.

Konopliv, Alexander S.↗

NASA NTRS2014

Automated Standard Hazard Tool

The current system used to generate standard hazard reports is considered cumbersome and iterative. This study defines a structure for this system's process in a clear, algorithmic way so that standard hazard reports and basic hazard analysis may be completed using a centralized, web-based computer application. To accomplish this task, a test server is used to host a prototype of the tool during development. The prototype is configured to easily integrate into NASA's current server systems with minimal alteration. Additionally, the tool is easily updated and provides NASA with a system that may grow to accommodate future requirements and possibly, different applications. Results of this project's success are outlined in positive, subjective reviews complete by payload providers and NASA Safety and Mission Assurance personnel. Ideally, this prototype will increase interest in the concept of standard hazard automation and lead to the full-scale production of a user-ready application.

Stebler, Shane↗