Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “chemical space”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Unexpected features in the optical vibrational spectra of δ-UO 3

Uranium trioxide displays a complex chemical phase space, with at least six structurally distinct polymorphs accessible via different synthetic routes. Remarkably, despite its technological importance, full structural and electronic characterization of these polymorphs remains an open area of study. δ-UO 3 in particular has attracted significant theoretical attention due to its high point group and space group symmetries, having U (VI) in octahedral coordination with polyhedra interconnected through corner-sharing to build a 3-D cubic lattice with space group symmetry Pm-3m and Z = 1. Critical experimental information, such as its optical vibrational spectra, are not known. Here, we study the Raman and infrared (IR) spectra of δ-UO 3 together with the support of density functional theory (DFT) calculations for spectral interpretation. A symmetry analysis of the DFT-predicted phonon eigenmodes indicates that δ-UO 3 should have two IR active modes and no Raman active modes. Experimental results, however, indicate significant Raman scattering from δ-UO 3 . We therefore propose four potential explanations for this apparent contradiction: a possible tetragonal distortion to the cubic cell, the existence of a surface impurity layer, vacancy scattering, and structural activation of Raman signal. We use powder X-ray diffraction and confocal Raman spectroscopy with depth profiling to investigate these possibilities and suggest future experiments to explore this phenomenon in more detail. Understanding the lattice dynamics of δ-UO 3 is important for identification of technogenic U phases via Raman and infrared spectroscopy and our results indicate that the simple understanding of δ-UO 3 as a high-symmetry cubic structure should be reconsidered.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
NASA NTRS1964

Nature of the space environment

Space environment exploration and chemical composition of cosmic radiation, meteoroid penetration rate, mass and frequency distribution

CHEMICAL COMPOSITION↗
NASA NTRS1977

Ninth Conference on Space Simulation

The papers presented in this conference provided an international dialogue and a meaningful exchange in the simulation of space environments as well as the evolution of these technological advances into other fields. The papers represent a significant contribution to the understanding of space simulation problems and the utilization of this knowledge. The topics of the papers include; spacecraft testing; facilities and test equipment; system and subsystem test; life sciences, medicine and space; physical environmental factors; chemical environmental factors; contamination; space physics; and thermal protection.

Source record↗
NASA NTRS1980

Technology requirements for future Earth-to-geosynchronous orbit transportation systems. Volume 2: Technical results

Technologies either critical to performance of offering cost advantages compared to the investment required to bring them to usable confidence levels are identified. A total transportation system is used as an evaluation yardstick. Vehicles included in the system are a single stage to orbit launch vehicle used in a priority cargo role, a matching orbit transfer vehicle, a heavy lift launch vehicle with a low Earth orbit delivery capability of 226, 575 kg, and a matching solar electric cargo orbit transfer vehicle. The system and its reference technology level are consistent with an initial operational capability in 1990. The 15 year mission scenario is based on early space industrialization leading to the deployment of large systems such as power satellites. Life cycle cost benefits in discounted and undiscounted dollars for each vehicle, technology advancement, and the integrated transportation system are calculated. A preliminary functional analysis was made of the operational support requirements for ground based and space based chemical propulsion orbit transfer vehicles.

Caluori, V. A.↗
NASA NTRS1985

Hydrogen-deficient atmospheres for cool carbon stars

Motivated by recent work which hints at a possible deficiency of hydrogen in non-Mira N-type carbon stars and to further explore the parameter space of chemical composition, computations have been made of a series of hydrogen-deficient models for carbon stars. For these models Teff = 3000 K, and log g = 0.0. Solar abundances are used for all elements except for carbon (which is enhanced to give C/O = 1.05), hydrogen, and helium. As the fractional abundance of hydrogen is decreased, being replaced by helium, the temperature-optical depth relation is affected only slightly, but the temperature-pressure relation is changed. The most striking change in the emergent flux is the decrease of the H(-) peak at 1.65 micron compared with the blackbody peak at 1.00 micron.

Johnson, H. R.↗
NASA NTRS1984

Chemical and biological evolution in space

The formation of organic molecules in interstellar dust grains and the survival of bacterial spores in a space environment are examined, summarizing the results of experimental investigations and theoretical calculations. The interstellar medium is characterized; the production of organic yellow-stuff residues on the mantles of dust grains in molecular clouds by UV radiation is explained; an IR absorption spectrum toward a Galactic-center source is shown to confirm the presence of such residues; and the mass of such abiotically produced complex organic molecules in the Galaxy is estimated as at least 10 to the 7th solar mass, or 0.1 percent of the mass in the Galaxy. This finding is considered significant for the prebiotic chemistry of the earth, since comets containing large amounts of interstellar dust may have impacted the earth many times during comet showers in the early solar system. UV-irradiation experiments on bacterial spores show that initial exposures to solar UV, not interstellar survival, is the main factor rendering theries of panspermia questionable.

Greenberg, J. M.↗
NASA NTRS1991

A coated-wire ion-selective electrode for ionic calcium measurements

A coated-wire ion-selective electrode for measuring ionic calcium was developed, in collaboration with Teknektron Sensor Development Corporation (TSDC). This coated wire electrode sensor makes use of advanced, ion-responsive polyvinyl chloride (PVC) membrane technology, whereby the electroactive agent is incorporated into a polymeric film. The technology greatly simplifies conventional ion-selective electrode measurement technology, and is envisioned to be used for real-time measurement of physiological and environment ionic constituents, initially calcium. A primary target biomedical application is the real-time measurement of urinary and blood calcium changes during extended exposure to microgravity, during prolonged hospital or fracture immobilization, and for osteoporosis research. Potential advanced life support applications include monitoring of calcium and other ions, heavy metals, and related parameters in closed-loop water processing and management systems. This technology provides a much simplified ionic calcium measurement capability, suitable for both automated in-vitro, in-vivo, and in-situ measurement applications, which should be of great interest to the medical, scientific, chemical, and space life sciences communities.

Hines, John W.↗
NASA NTRS1991

Model-based task planning system for a space laboratory environment

This paper describes the design of a model-based autonomous planning system that will enable robots to manage a space-borne chemical laboratory. In a model-based planning system, knowledge is encapsulated in the form of models at the various layers to support the predefined system objectives. Thus the model-based approach can be considered as an extended planning paradigm which is able to base its planning, control, diagnosis, repair, and other activities on a variety of objectives-related models. A System Entity Structure/Model Base framework is employed to support autonomous system design through the ability to generate a family of planning alternatives as well as to build hierarchical event-based control structures. The model base is a multilevel, multiabstraction, and multiformalism system organized through the use of system morphisms to integrate related models.

Chi, Sung-Do↗
NASA NTRS1990

Low Thrust Propulsion

This video presents an overview of low thrust rocket engine propulsion concepts for space missions. Chemical and electrical rocket engines are shown. Animation illustrates various propulsion applications.

Source record↗
NASA NTRS1995

Development of improved space sampling strategies for ocean chemical properties: Total carbon dioxide and dissolved nitrate

Large-scale ocean observing programs such as the Joint Global Ocean Flux Study (JGOFS) and the World Ocean Circulation Experiment (WOCE) today, must face the problem of designing an adequate sampling strategy. For ocean chemical variables, the goals and observing technologies are quite different from ocean physical variables (temperature, salinity, pressure). We have recently acquired data on the ocean CO2 properties on WOCE cruises P16c and P17c that are sufficiently dense to test for sampling redundancy. We use linear and quadratic interpolation methods on the sampled field to investigate what is the minimum number of samples required to define the deep ocean total inorganic carbon (TCO2) field within the limits of experimental accuracy (+/- 4 micromol/kg). Within the limits of current measurements, these lines were oversampled in the deep ocean. Should the precision of the measurement be improved, then a denser sampling pattern may be desirable in the future. This approach rationalizes the efficient use of resources for field work and for estimating gridded (TCO2) fields needed to constrain geochemical models.

Goyet, Catherine↗
NASA NTRS1996

Immobile Robots: AI in the New Millennium

A new generation of sensor rich, massively distributed, autonomous systems are being developed that have the potential for profound social, environmental, and economic change. These include networked building energy systems, autonomous space probes, chemical plant control systems, satellite constellations for remote ecosystem monitoring, power grids, biosphere-like life support systems, and reconfigurable traffic systems, to highlight but a few. To achieve high performance, these immobile robots (or immobots) will need to develop sophisticated regulatory and immune systems that accurately and robustly control their complex internal functions. To accomplish this, immobots will exploit a vast nervous system of sensors to model themselves and their environment on a grand scale. They will use these models to dramatically reconfigure themselves in order to survive decades of autonomous operations. Achieving these large scale modeling and configuration tasks will require a tight coupling between the higher level coordination function provided by symbolic reasoning, and the lower level autonomic processes of adaptive estimation and control. To be economically viable they will need to be programmable purely through high level compositional models. Self modeling and self configuration, coordinating autonomic functions through symbolic reasoning, and compositional, model-based programming are the three key elements of a model-based autonomous systems architecture that is taking us into the New Millennium.

Williams, Brian C.↗
NASA NTRS2003

Dynamical Study of Prebiotic Processing by Comet Impact

Comets and meteoroids that bombarded the Earth, other planets and moons are considered possible deliverers of prebiotic materials manufactured in space. Simultaneously, chemical processing can be initiated by the large kinetic energy imparted to the planetary atmosphere during comet/meteoroid entry. The efficiency of organic synthesis and the diversity of products by impact shock are known to decrease as the reducing power of the atmosphere decreases. It is generally accepted that rich organic products are produced in a methane atmosphere whereas a carbon dioxide atmosphere is reported to yield a dearth of products In order to understand the details of impact chemistry and how it depends on the atmospheric composition, we carried out simulations of the chemistry initiated by comet/meteoroid impact upon a planetary atmosphere using different atmospheric compositions. The simulations were done by solving the set of coupled equations for mass, momentum, and energy conservations, chemical kinetics, and transport, that describe a high-energy impact shock, subsequent expansion and cooling of the hot shocked gas by mixing with the ambient gas, and the eventual steady state composition.

Huo, Winifred M.↗
NASA NTRS2001

Physical-Chemical Solid Waste Processing for Space Missions at Ames Research Center

As space missions become longer in duration and reach out to more distant locations such as Mars, solids waste processing progresses from storage technologies to reclamation technologies. Current low Earth orbit technologies consist of store-and dispose to space or return to Earth. Fully regenerative technologies recycle wastes. The materials reclaimed from waste can be used to provide the basic materials to support plant growth for food including carbon dioxide, water, and nutrients. Other products can also be reclaimed from waste such as hydrocarbons and activated carbon. This poster describes development at Ames Research Center of a process to make activated carbon from space mission wastes and to make an incineration system that produces clean flue gas. Inedible biomass and feces contain hydrocarbons in a form that can be pyrolyzed and converted to activated carbon. The activated carbon can then be used to clean up contaminants from various other life support systems; in particular, the activated carbon can be used regeneratively to remove NOx from incinerator flue gas. Incinerator flue gas can also be cleaned up by the use of reductive and oxidative catalysts. A catalytic incinerator flue gas cleanup system has been developed at ARC that produces flue gas clean enough (with the exception of carbon dioxide) to meet the Space Minimum Allowable Concentration limits for human exposure.

Fisher, John W.↗
NASA NTRS2006

Deep-UV Based Acousto-Optic Tunable Filter for Spectral Sensing Applications

In this paper, recent progress made in the development of quartz and KDP crystal based acousto-optic tunable filters (AOTF) are presented. These AOTFs are developed for operation over deep-UV to near-UV wavelengths of 190 nm to 400 nm. Preliminary output performance measurements of quartz AOTF and design specifications of KDP AOTF are presented. At 355 nm, the quartz AOTF device offered approx.15% diffraction efficiency with a passband full-width-half-maximum (FWHM) of less than 0.0625 nm. Further characterization of quartz AOTF devices at deep-UV wavelengths is progressing. The hermetic packaging of KDP AOTF is nearing completion. The solid-state optical sources being used for excitation include nonlinear optics based high-energy tunable UV transmitters that operate around 320 nm and 308 nm wavelengths, and a tunable deep-UV laser operating over 193 nm to 210 nm. These AOTF devices have been developed as turn-key devices for primarily for space-based chemical and biological sensing applications using laser induced Fluorescence and resonance Raman techniques.

Prasad, Narasimha S.↗
NASA NTRS2017

Microbial Extremophiles for Earth and Beyond: Pushing the Boundaries with Synthetic Biology

All organisms live in a multi-dimensional physical and chemical niche space. Discoveries in the 20th century enormously expanded the range of what was considered "habitable." However, the current diversity of life on Earth begs the question of what terrestrial life - or indeed, another life form - would be capable of. With the needs of both modern laboratory science and the burgeoning field of biotechnology, as well as our deeply held desire to answer the question "are we alone in the universe?, we are exploiting the tools of synthetic biology to probe the question of whether we can create "synthetic extremophiles" or, as our lab has dubbed them, "Hell Cells."

synthetic extremophiles↗
NASA NTRSDate not supplied

Dissociative Recombination (DR) and Associative Ionization (AI) Cross Section Calculations for the NO+ + e yields N + O (2D+3P, 2P+3P, and 2D+1D) Reaction for Atmospheric Entry Modeling

During entry of a space craft into Earth atmosphere, the flow surrounding the vehicle becomes partially ionized leading to significant cation and free-electron production. Subsequently, electron impact excitation and dissociation form radiating excited state species that contribute to the heat load on the vehicle. While experimental data on selected total cross sections are available, few experiments address the need for accurate AI cross sections for metastable atomic states at the high temperatures realized in atmospheric re-entry. In order to maintain desired safety margins during atmospheric entry of a space vehicle, chemical reaction models need to accurately account for this process. For the present study, we have computed vibrationally resolved cross sections for the DR of NO+ for electron energies between 0.01 to 10 eV and apply microscopic reversibility to obtain the AI cross sections and rate coefficients. For the DR cross section calculations, we use state-of-the-art MRCI potential energy curves. The resulting adiabatic potential curves are transformed to a diabatic representation, which is used in time-dependent wave packet calculations to describe the nuclear motion of the dissociating cation upon collision with an electron. Based on the wave function evolution in time, these calculations provide T-matrix and cross sections for the DR including recombination into the low energy metastable atomic states. The DR and AI rate coefficients are compared with the available experimental data.

Ewa Papajak↗
NASA NTRSDate not supplied

Surge Pressure Testing of Flight-Like Components

This project studies the transient surge pressure effects (such as those observed during propulsion system priming) on flight components. A water flow setup was used to impart transient surge pressures on flight-like components. The project compared the point of component failure for transient surge pressures versus static proof pressures. Results showed that designing to keep surge pressures below component proof pressures is overly conservative, because the components can handle higher transient pressures. The tests performed on burst discs showed that the rupture pressure under a transient surge pressure was at least 20% above the static rupture pressure. A tested pressure transducer remained fully functional and accurate after surge pressures 60% above its specified proof pressure. A thruster valve was exposed to transient surge pressures four times its specified proof pressure and showed no indications of damage.

propulsion components↗