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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

Comparison of chemical lateral boundary conditions for air quality predictions over the contiguous United States during pollutant intrusion events

The National Air Quality Forecast Capability (NAQFC) operated in U.S.’s National Oceanic and Atmospheric Administration (NOAA) provides the operational forecast guidance for ozone and fine particulate matters with aerodynamic diameters less than 2.5μm (PM2.5) over the contiguous 48 U.S. states (CONUS) using the Community Multi-scale Air Quality (CMAQ) model. The existing NAQFC uses climatological chemical lateral boundary conditions ( CLBCs), which cannot capture pollutant intrusion events originating outside of the model domain. In this study, we developed a model framework to use dynamic CLBCs from the Goddard Earth Observing System Model, version 5 (GEOS) to drive NAQFC. A mapping of the GEOS chemical species to the CMAQ’s Carbon Bond 5 (CB05)-Aero6 species was developed. The utilization of the GEOS dynamic CLBCs in NAQFC showed the best overall performance in simulating the surface observations during the Saharan dust intrusion and Canadian wildfire events in summer 2015.The simulated PM2.5 was improved from 0.18 to 0.37 and the mean bias was reduced from -6.74 μg/m3 to -2.96 μg/m3 over CONUS. Although the effect of CLBCs on the PM2.5 correlation was mainly near the inflow boundary, its impact on the background concentrations reached further inside the domain. The CLBCs could affect background ozone concentrations through the inflows of ozone itself and its precursors, such as CO. It was further found that the aerosol optical thickness (AOT) from satellite retrievals correlated well with the column CO and elemental carbon from GEOS. The satellite-derived AOT CLBCs generally improved the model performance for the wildfire intrusion events during a summer 2018 case study, and demonstrated how satellite observations of atmospheric composition could be used as an alternative method to capture the air quality effects of intrusions when the global model CLBCs, such as GEOS CLBCs, are not available.

Community Multi-scale Air Quality (CMAQ) model↗
NASA NTRS2001

Multifunctional Carbon Foams for Aerospace Applications

Carbon foams produced by the controlled thermal decomposition of inexpensive coal extracts exhibit a combination of structural and thermal properties that make them attractive for aerospace applications. Their thermal conductivity can be tailored between 0.5 and 100 W/mK through precursor selection/modification and heat treatment conditions; thus, they can serve in either thermal protection or heat transfer systems such as heat exchangers. Because their structure is essentially a 3D random network of graphite-like members, they also can be considered low-cost, easily fabricated replacements for multi-directional structural carbon fiber preforms. Strengths of over 4000 psi in compression are common. Their density can be designed between 0.1 and 0.8 g/cc, and they can be impregnated with a variety of matrices or used, unfilled, in sandwich structures. These foams also exhibit intriguing electrochemical properties that offer potential in high-efficiency fuel cell and battery applications, mandrels and tooling for composite manufacture, ablative performance, and fire resistance. This paper presents the results of research conducted under NASA SBIR Topic 99.04.01, General Aviation Technology, supported from Langley Research Center. The potential of foam design through precursor selection, cell size and density control, density grading, and heat treatment is demonstrated.

Rogers, D. K.↗
NASA NTRS1993

Reflectance spectra of sulfate-and carbonate-bearing Fe(3+)-doped montmorillonites as Mars soil analogs

Ferric smectites and ferrihydrite may be common alteration products of igneous lithologies on Mars, and experiments involving montmorillonite enriched with Fe(3+) support the likelihood of ferric smectites on Mars. Mossbauer spectroscopy has been used to identify ferrihydrite (Fe4(O,OH,H2O)12) as the primary ferric material in Fe(3+)-doped montmorillonite. Ferrihydrite is especially interesting due to its role as a precursor in the formation of hematite and goethite. Reflectance spectroscopy in the visible and infrared regions are coupled with Mossbauer spectroscopy in this study to characterize the ferric material in montmorillonites containing Fe(3+), as well as carbonates or sulfates, in the interlayer region.

Bishop, Janice L.↗
NASA NTRS2005

Interstellar PAH in the Laboratory and in Space. What have we Learned from the New Generation of Laboratory and Observational Studies?

Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. PAHs are the best-known candidates to account for the IR emission bands (UIR bands) and PAH spectral features are now being used as new probes of the ISM. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory astrophysics is to reproduce (in a realistic way) the physical conditions that exist in the emission and/or absorption interstellar zones. An extensive laboratory program has been developed at NASA Ames to assess the physical and chemical properties of PAHs in such environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. In particular, laboratory experiments provide measurements of the spectral characteristics of interstellar PAH analogs from the ultraviolet and visible range to the infrared range for comparison with astronomical data. This paper will focus on the recent progress made in the laboratory to measure the direct absorption spectra of neutral and ionized PAHs in the gas phase in the near-UV and visible range in astrophysically relevant environments. These measurements provide data on PAHs and nanometer-sized particles that can now be directly compared to astronomical observations. The harsh physical conditions of the IS medium - characterized by a low temperature, an absence of collisions and strong VUV radiation fields - are simulated in the laboratory by associating a molecular beam with an ionizing discharge to generate a cold plasma expansion. PAH ions are formed from the neutral precursors in an isolated environment at low temperature (of the order of 100 K). The spectra of neutral and ionized PAHs are measured using the high sensitivity methods of cavity ring down spectroscopy (CRDS). These experiments provide unique information on the spectra of free, cold large carbon molecules and ions in the gas phase. Intrinsic band profiles and band positions of cold gas-phase PAHs can now be measured with high-sensitivity spectroscopy and directly compared to the astronomical data. The electronic bands measured for ionized PAH are found to be intrinsically broad (about 20 cm(sup -1)) while the bands associated with the neutral precursors are narrower (of the order of 2 - 10 cm(sup -1)). The laboratory data are discussed and compared with recent astronomical spectra of large and narrow DIBs and with the spectra of circumstellar environments of selected carbon stars and the implications for the interstellar PAH population are derived. Preliminary results also show that carbon nanoparticles are formed during the short residence time of the precursors in the plasma.

Salama, Farid↗
NASA NTRS1992

Emissions of sulfur gases from wetlands

Data on the emissions of sulfur gases from marine and freshwater wetlands are summarized with respect to wetland vegetation type and possible formation mechanisms. The current data base is largest for salt marshes inhabited by Spartina alterniflora. Both dimethyl sulfide (DMS) and hydrogen sulfide (H2S) dominate emissions from salt marshes, with lesser quantities of methyl mercaptan (MeSH), carbonyl sulfide (COS), carbon disulfide (CS2) and dimethyl disulfide (DMDS) being emitted. High emission rates of DMS are associated with vegetation that produces the DMS precursor dimethylsulfonionpropionate (DMSP). Although large quantities of H2S are produced in marshes, only a small percentage escapes to the atmosphere. High latitude marshes emit less sulfur gases than temperate ones, but DMS still dominates. Mangrove-inhabited wetlands also emit less sulfur than temperate S. alterniflora marshes. Few data are available on sulfur gas emissions from freshwater wetlands. In most instances, sulfur emissions from temperate freshwater sites are low. However, some temperate and subtropical freshwater sites are similar in magnitude to those from marine wetlands which do not contain vegetation that produces DMSP. Emissions are low in Alaskan tundra but may be considerably higher in some bogs and fens.

Hines, Mark E.↗
NASA NTRS1997

A laboratory analog for the carrier of the 3 micron emission of the protoplanetary nebula IRAS 05341+0852

A mixture of the polycyclic aromatic hydrocarbons (PAHs), acenaphthylene and acenaphthene, when subjected to the energetic environment of a hydrogen plasma, is transformed into a material that exhibits an infrared absorption profile in the 3 micron region that is an excellent match of the protoplanetary nebula IRAS 05341+0852 emission profile in the same wavelength region. Acenaphthylene and acenaphthene were chosen as precursors in the experiment because these molecules have a structure that can be described as a keystone in a process in which carbon atoms in a stellar wind condense into PAH species. The spectral match between experiment and observations appears to validate that scenario.

Non-NASA Center↗
NASA NTRS1979

Non-flammable polyimide materials for commercial application

Thermally-stable, fire-resistant polyimide foams developed for use as fire protection in aircraft, spacecraft and ground applications are presented. Polyimide precursors, synthesized by the reaction of 3, 3', 4, 4'-benzophenone tetracarboxylic acid dianhydride with a mixture of two diamines, can be processed into foams by indirect or direct heating techniques. Flexible resilient foams and thermal acoustical foams produced by the microwave heating of polyimide precursors are shown to conform to requirements for aircraft seating foams and thermal and acoustical insulation materials, respectively. Rigid polyimide foams reinforced by carbon mat, chopped carbon mat and chopped glass strand fillers and prepared by the microwave heating of a continuous mat, followed by its compression, or by filling a honeycomb structure with low density foam, are found to exhibit outstanding fire resistance and have mechanical properties approaching those desired for structural materials.

Gagliani, J.↗
NASA NTRS2007

Ultra-Lightweight Hybrid Thin-Film Solar Cells: A Survey of Enabling Technologies for Space Power Applications

The development of hybrid inorganic/organic thin-film solar cells on flexible, lightweight, space-qualified, durable substrates provides an attractive solution for fabricating solar arrays with high mass specific power (W/kg). Next generation thin-film technologies may well involve a revolutionary change in materials to organic-based devices. The high-volume, low-cost fabrication potential of organic cells will allow for square miles of solar cell production at one-tenth the cost of conventional inorganic materials. Plastic solar cells take a minimum of storage space and can be inflated or unrolled for deployment. We will explore a cross-section of in-house and sponsored research efforts that aim to provide new hybrid technologies that include both inorganic and polymer materials as active and substrate materials. Research at University of Texas at Arlington focuses on the fabrication and use of poly(isothianaphthene-3,6-diyl) in solar cells. We describe efforts at Norfolk State University to design, synthesize and characterize block copolymers. A collaborative team between EIC Laboratories, Inc. and the University of Florida is investigating multijunction polymer solar cells to more effectively utilize solar radiation. The National Aeronautics and Space Administration (NASA)/Ohio Aerospace Institute (OAI) group has undertaken a thermal analysis of potential metallized substrates as well as production of nanoparticles of CuInS2 and CuInSe2 in good yield at moderate temperatures via decomposition of single-source precursors. Finally, preliminary work at the Rochester Institute of Technology (R.I.T.) to assess the impact on performance of solar cells of temperature and carbon nanotubes is reported. Technologies that must be developed to enable ultra-lightweight solar arrays include: monolithic interconnects, lightweight array structures, and new ultra-light support and deployment mechanisms. For NASA applications, any solar cell or array technology must not only meet weight and AMO efficiency goals, but also must be durable enough to survive launch conditions and space environments.

Hepp, Aloysius F.↗
NASA NTRS2016

Global and Regional Radiative Forcing from 20 Reductions in BC, OC and SO4 an HTAP2 Multi-Model Study

In the Hemispheric Transport of Air Pollution Phase 2 (HTAP2) exercise, a range of global atmospheric general circulation and chemical transport models performed coordinated perturbation experiments with 20% reductions in emissions of anthropogenic aerosols, or aerosol precursors, in a number of source regions. Here, we compare the resulting changes in the atmospheric load and vertically resolved profiles of black carbon (BC), organic aerosols (OA) and sulfate (SO4/ from 10 models that include treatment of aerosols. We use a set of temporally, horizontally and vertically resolved profiles of aerosol forcing efficiency (AFE) to estimate the impact of emission changes in six major source regions on global radiative forcing (RF) pertaining to the direct aerosol effect, finding values between. 51.9 and 210.8mW/sq m/Tg for BC, between -2.4 and -17.9mW/sq m/Tg for OA and between -3.6 and -10.3W/sq m/Tg for SO4. In most cases, the local influence dominates, but results show that mitigations in south and east Asia have substantial impacts on the radiative budget in all investigated receptor regions, especially for BC. In Russia and the Middle East, more than 80 % of the forcing for BC and OA is due to extra-regional emission reductions. Similarly, for North America, BC emissions control in east Asia is found to be more important than domestic mitigations, which is consistent with previous findings. Comparing fully resolved RF calculations to RF estimates based on vertically averaged AFE profiles allows us to quantify the importance of vertical resolution to RF estimates. We find that locally in the source regions, a 20% emission reduction strengthens the radiative forcing associated with SO4 by 25% when including the vertical dimension, as the AFE for SO4 is strongest near the surface. Conversely, the local RF from BC weakens by 37% since BC AFE is low close to the ground. The fraction of BC direct effect forcing attributable to intercontinental transport, on the other hand, is enhanced by one-third when accounting for the vertical aspect, because long-range transport primarily leads to aerosol changes at high altitudes, where the BC AFE is strong. While the surface temperature response may vary with the altitude of aerosol change, the analysis in the present study is not extended to estimates of temperature or precipitation changes.

profiles of aerosol forcing efficiency (AFE)↗
NASA NTRSDate not supplied

In-Situ Reaction Monitoring for Lunar Applications Utilizing a Single Quadrupole Residual Gas Analyzer

With a revived focus to create a permeant presence on the moon and in preparation for future Mars exploration, it is imperative that all re-sources are utilized to their fullest potential. In-Situ Resource Utilization (ISRU) will be critical for future mission success as it would enable independent operation of missions while minimally relying on the complex supply chain created between the Earth, moon and Mars. One of the most critical resources that have been identified for ISRU is the creation of liquid oxygen (O2) for not only breathable air, but also for rocket fuel. On the moon and potentially Mars, one of the most O2 rich resources is in the presence of regolith. Although there are numerous minerals within regolith and various processes to extract O2, this is not the scope of this paper. Since the O2 extraction method can vary, a critical standardized analytical method is needed to verify O2 (or oxygenated precursor compounds) for extraction efficiency and purity. Our group utilizes a modified consumer off-the-shelf (COTS), Residual Gas Analyzer (RGA) Single Quadrupole Mass Spectrometer (QMS). Due to the current field mission requirements, the gas analysis module will need to rely only on mass-to-charge ratios (m/z) and peak intensities to differentiate and quantitate targeted gas-phase reactants or products, i.e. carbon monoxide (CO), carbon dioxide (CO2), methane (CH4) and hydrogen (H2). However, due to solar wind implanted volatiles and various other compounds present in lunar regolith, such as nitrogen (N2), helium (He), and deuterium (D2), deconvolution and quantification of isobaric compounds becomes quite difficult. Specifically, the presence of N2 makes quantification of CO, an oxygenated precursor, difficult due to both compounds having a peak at m/z 28. Approaches to differentiate isobaric components: Initially, the solution to overcome isobaric overlap was to use isotopic ratios, particularly be-tween carbon-13 and nitrogen-15. Although limited literature discuss isotopic composition and attempt to quantify the ratios, variation is particularly high and limited to a few lunar regolith samples. The following were identified as potential approaches to quantify isobaric species, N2 and CO, using our RGA. Threshold Ionization. CO and N2 both have peaks at m/z 28, but only N2 is capable of producing a peak at m/z 7. While a N2 peak at m/z 7 is generally rare, instrument parameters can be optimized in order to maximize the peak intensity. Typically a standard ionization energy of 70 eV is used to monitor a batch process and would produce reliable results for a majority of the reactants or products that we are interested in quantifying. However, to analyze the rare molecular fragment of N2 (N2+ at m/z 7), a different ionization energy may be beneficial. Threshold Ionization Mass Spectrometry (TIMS) will be explored to optimize the N2+ peak at m/z 7 by varying parameters such as ionization energy and pressure. Therefore, a quantitative value at m/z 7 will be used to determine the product gas concentration of N2, which will be subtracted from the total concentration determined at m/z 28 enabling us to approximate the amount of CO. Secondary Detector (infrared gas detector, IR). Another approach to quantitate and differentiate be-tween isobaric components is to leverage alternative modes of detection. Unlike mass spectrometry, which generally uses a separation step prior to analysis (i.e. gas chromatography), IR produces energy that is specifically absorbed depending on the bond and configuration of the molecule. This technique could be leveraged since it is generally only active on non-symmetric molecules, i.e. CO. Utilizing concentrations of CO determined from another detector could help correct concentrations of CO obtained from the QMS. However, the inclusion of another detector adds additional mission requirements, such as power, software changes and avionics updates that add additional cost and schedule requirements.

mass spectrometry↗
NASA NTRS1984

Thermogravimetric analysis of silicon carbide-silicon nitride polycarbosilazane precursor during pyrolysis from ambient to 1000 C

Thermogravimetric analysis data are presented on the unmeltable polycarbosilazane precursor of silicon carbide-silicon nitride fibers, over the room temperature-1000 C range in a nitrogen atmosphere, in order to establish the weight loss at various temperatures during the precursor's pyrolysis to the fiber material. The fibers obtained by this method are excellent candidates for use in applications where the oxidation of carbon fibers (above 400 C) renders them unsuitable.

Ledbetter, F. E., III↗
NASA NTRS2002

Chemical constraints governing the origin of metabolism: the thermodynamic landscape of carbon group transformations under mild aqueous conditions

The thermodynamics of organic chemistry under mild aqueous conditions was examined in order to begin to understand its influence on the structure and operation of metabolism and its antecedents. Free energies (deltaG) were estimated for four types of reactions of biochemical importance carbon-carbon bond cleavage and synthesis, hydrogen transfer between carbon groups, dehydration of alcohol groups, and aldo-keto isomerization. The energies were calculated for mainly aliphatic groups composed of carbon, hydrogen, and oxygen. The energy values showed (1) that generally when carbon-carbon bond cleavage involves groups from different functional group classes (i.e., carboxylic acids, carbonyl groups, alcohols, and hydrocarbons), the transfer of the shared electron-pair to the more reduced carbon group is energetically favored over transfer to the more oxidized carbon group, and (2) that the energy of carbon-carbon bond transformation is primarily determined by the functional group class of the group that changes oxidation state in the reaction (i.e., the functional group class of the group that donates the shared electron-pair during cleavage, or that accepts the incipient shared electron-pair during synthesis). In contrast, the energy of hydrogen transfer between carbon groups is determined by the functional group class of both the hydrogen-donor group and the hydrogen-acceptor group. From these and other observations we concluded that the chemistry involved in the origin of metabolism (and to a lesser degree modern metabolism) was strongly constrained by (1) the limited redox-based transformation energy of organic substrates that is readily dissipated in a few energetically favorable irreversible reactions; (2) the energy dominance of a few transformation half-reactions that determines whether carbon-carbon bond transformation (cleavage or synthesis) is energetically favorable (deltaG < -3.5 kcal/mol), reversible (deltaG between +/-3.5 kcal/mol), or unfavorable (deltaG > +3.5 kcal/mol); and (3) the dependence of carbon group transformation energy on the functional group class (i.e., oxidation state) of participating groups that in turn is contingent on prior reactions and precursors in the synthetic pathway.

Carbon/chemistry/metabolism↗
NASA NTRS2015

Bulk Preparation of Holey Graphene via Controlled Catalytic Oxidation

A scalable method allows preparation of bulk quantities of holey carbon allotropes with holes ranging from a few to over 100 nm in diameter. Carbon oxidation catalyst nanoparticles are first deposited onto a carbon allotrope surface in a facile, controllable, and solvent-free process. The catalyst-loaded carbons are then subjected to thermal treatment in air. The carbons in contact with the carbon oxidation catalyst nanoparticles are selectively oxidized into gaseous byproducts such as CO or CO.sub.2, leaving the surface with holes. The catalyst is then removed via refluxing in diluted nitric acid to obtain the final holey carbon allotropes. The average size of the holes correlates strongly with the size of the catalyst nanoparticles and is controlled by adjusting the catalyst precursor concentration. The temperature and time of the air oxidation step, and the catalyst removal treatment conditions, strongly affect the morphology of the holes.

Watson, Kent↗
NASA NTRS2017

Pathways to Meteoritic Glycine and Methylamine

Glycine and methylamine are meteoritic water-soluble organic compounds that provide insights into the processes that occurred before, during, and after the formation of the Solar System. Both glycine and methylamine and many of their potential synthetic precursors have been studied in astrophysical environments via observations, laboratory experiments, and modeling. Despite these studies, the synthetic mechanisms for their formation leading to their occurrence in meteorites remain poorly understood. Typical 13C-isotopic values ((delta)13C) of meteoritic glycine and methylamine are 13C-enriched relative to their terrestrial counterparts; thus, analyses of their stable carbon isotopic compositions (13C/12C) may be used not only to assess terrestrial contamination in meteorites but also to provide information about their synthetic routes inside the parent body. Here, we examine potential synthetic routes of glycine and methylamine from a common set of precursors present in carbonaceous chondrite meteorites, using data from laboratory analyses of the well-studied CM2 Murchison meteorite. Several synthetic mechanisms for the origins of glycine and methylamine found in carbonaceous chondrites may be possible, and the prevalence of these mechanisms will largely depend on (a) the molecular abundance of the precursor molecules and (b) the levels of processing (aqueous and thermal) that occurred inside the parent body. In this work, we also aim to contextualize the current knowledge about gas-phase reactions and irradiated ice grain chemistry for the synthesis of these species through parent body processes. Our evaluation of various mechanisms for the origins of meteoritic glycine and methylamine from simple species shows what work is still needed to evaluate both the abundances and isotopic compositions of simpler precursor molecules from carbonaceous chondrites as well as the effects of parent body processes on those abundances and isotopic compositions. The analyses presented here combined with the indicated measurements will aid a better interpretation of quantitative analysis of reaction rates, molecular stability, and distribution of organic products from laboratory simulations of interstellar ices, astronomical observations, and theoretical modeling.

interstellar ice↗
NASA NTRS1987

Silsesquioxanes as precursors to ceramic composites

Silsesquioxanes having the general structure RSiO(1.5), where R = methyl, propyl, or phenyl, melt flow at 70 to 100 C. Above 100 C, free OH groups condense. At 225 C further crosslinking occurs, and the materials form thermosets. Pyrolysis, with accompanying loss of volatiles, takes place at nominally 525 C. At higher temperatures, the R group serves as an internal carbon source for carbo-thermal reduction to SiC accompanied by the evolution of CO. By blending silsesquioxanes with varying R groups, both the melt rheology and composition of the fired ceramic can be controlled. Fibers can be spun from the melt which are stable in argon in 1400 C. The silsesquioxanes also were used as matrix precursors for Nicalon and alpha-SiC platelet reinforced composites.

Hurwitz, F. I.↗
NASA NTRS1987

Silsesquioxanes as precursors to ceramic composites

Silsesquioxanes having the general structure RSiO sub 1.5, where R = methyl, propyl, or phenyl, melt flow at 70 to 100 C. Above 100 C, free -OH groups condense. At 225 C further crosslinking occurs, and the materials form thermosets. Pyrolysis, with accompanying loss of volatiles, takes place at nominally 525 C. At higher temperatures, the R group serves as an internal carbon soruce for carbo-thermal reduction to SiC accompanied by the evolution of CO. By blending silsesquioxanes with varying R groups, both the melt rheology and composition of the fired ceramic can be controlled. Fibers can be spun from the melt which are stable in argon in 1400 C. The silsesquioxanes also were used as matrix precursors for Nicalon and alpha-SiC platelet reinforced composites.

Hurwitz, Frances I.↗
NASA NTRS2001

Chemical State of Surface Oxygen on Carbon and Its Effects on the Capacity of the Carbon Anode in a Lithium-Ion Battery Investigated

In a lithium-ion battery, the lithium-storage capacity of the carbon anode is greatly affected by a surface layer formed during the first half cycle of lithium insertion and release into and out of the carbon anode. The formation of this solid-electrolyte interface, in turn, is affected by the chemistry of the carbon surface. A study at the NASA Glenn Research Center examined the cause-and-effect relations. Information obtained from this research could contribute in designing a high-capacity lithium-ion battery and, therefore, small, powerful spacecraft. In one test, three types of surfaces were examined: (1) a surface with low oxygen content (1.5 at.%) and a high concentration of active sites, (2) a surface with 4.5 at.% -OH or -OC type oxygen, and (3) a surface with 6.5 at.% O=C type oxygen. The samples were made from the same precursor and had similar bulk properties. They were tested under a constant current of 10 mA/g in half cells that used lithium metal as the counter electrode and 0.5 M lithium iodide in 50/50 (vol%) ethylene carbonate and dimethyl carbonate as the electrolyte. For the first cycle of the electrochemical test, the graph describes the voltage of the carbon anode versus the lithium metal as a function of the capacity (amount of lithium insertion or release). From these data, it can be observed that the surface with low oxygen and a high concentration of active sites could result in a high irreversible capacity. Such a high irreversible capacity could be prevented if the active sites were allowed to react with oxygen in air, producing -OH or -OC type oxygen. The O=C type oxygen, on the other hand, could greatly reduce the capacity of lithium intercalation and, therefore, needs to be avoided during battery fabrication.

Hung, Ching-Cheh↗
NASA NTRS1991

Chemical approaches to carbon dioxide utilization for manned Mars missions

Utilization of resources available in situ is a critical enabling technology for permanent human presence in space. A permanent presence on Mars, for example, requires a tremendous infrastructure to sustain life under hostile conditions (low oxygen, partial pressure, ultraviolet radiation, low temperature, etc.). There are numerous studies on the most accessible of Martian resources: atmospheric carbon dioxide. As a resource on Mars, atmospheric CO2 is: (1) abundant; (2) available at all points on the surface; (3) of known presence, requiring no precursor mission to verify; (4) chemically simple; and (5) can be obtained by simple compression, with no requirements of mining or beneficiation equipment operation. Several novel proposals are presented for CO2 fixation through chemical, photochemical, and photoelectrochemical means.

Hepp, Aloysius F.↗