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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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102 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Detection Opportunity for Aromatic Signature in Titan's Aerosols in the 4.1-5.3 μm Range

The Cassini/Huygens mission provided new insights on the chemistry of the upper atmosphere of Titan. The presence of large molecules and ions (>100's of amu) detected by Cassini at high altitude was not expected, and questions the original assumptions regarding the aerosol formation pathways. From recent laboratory studies, it has been shown that the inclusion of trace amounts of aromatic species drastically impacts the chemistry of aerosol formation and induces observable changes in the properties of the aerosols. In this Letter we focus on the effect of one of the simplest nitrogenous aromatics, pyridine (C5H5N), on the infrared signature of Titan's aerosol analogs. We introduce initial gas mixtures of (i) N2–C5H5N (100%/250 ppm), (ii) N2–CH4–C5H5N (99%/1%/250 ppm), and (iii) N2–CH4 (99%/1%) in a cold plasma discharge. The material produced, herein called tholins, is then analyzed by mid-infrared spectroscopy. When adding pyridine in the discharge, the tholins produced present an aromatic signature in the 4.1–5.3 μm (1850–2450 cm−1) spectral region, attributed to overtones of aromatic C–H out-of-plane bending vibrations. We also observe a spectral shift of the nitrile and iso-nitrile absorption band with the inclusion of pyridine in the gas mixture. These results could help to investigate the data obtained at Titan by the Cassini/Visual and Infrared Mapping Spectrometer (VIMS) instrument in the 1–5 μm infrared window.

Mathé, Christophe↗
NASA NTRSDate not supplied

Integrated laboratory, modeling and observational investigations of the condensation of benzene on Titan's stratospheric aerosols

Aerosols in Titan’s atmosphere play an important role in determining its thermal structure and can act as condensation nuclei for the formation of clouds. The global circulation of Titan’s atmosphere reversed within the two years following the northern spring equinox in August 2009, increasing the mixing ratios of benzene (C6H6) and other species at the South pole. A simultaneous strong cooling above the south pole (dropping temperatures below 120 K) resulted in conditions where molecules could condense at unusually high altitudes (>250 km). C6H6 and HCN ices have been detected by the Composite Infrared Spectrometer (CIRS) and the Visible and Infrared Mapping Spectrometer (VIMS), respectively, in the South polar cloud system, but the existing laboratory data is insufficient to allow models to reproduce the formation of the observed cloud system. We will present the preliminary results and the overall scope of a newly funded NASA SMD Cassini Data Analysis Program (CDAP) project which proposes to combine laboratory, modeling and observational studies to investigate the condensation of benzene on Titan’s aerosol as an important component of the cloud system that appeared during the autumn at 300 km above Titan’s South pole.

E. Sciamma-O’Brien↗
NASA NTRS2018

Organic Ices in Titan's Stratosphere

Titan’s stratospheric ice clouds are by far the most complex of any observed in the solar system, with over a dozen organic vapors condensing out to form a suite of pure and co-condensed ices, typically observed at high winter polar latitudes. Once these stratospheric ices are formed, they will diffuse throughout Titan’s lower atmosphere and most will eventually precipitate to the surface, where they are expected to contribute to Titan’s regolith. Early and important contributions were first made by the InfraRed Interferometer Spectrometer (IRIS) on Voyager 1, followed by notable contributions from IRIS’ successor, the Cassini Composite InfraRed Spectrometer (CIRS), and to a lesser extent, from Cassini’s Visible and Infrared Mapping Spectrometer (VIMS) and the Imaging Science Subsystem (ISS) instruments. All three remote sensing instruments made new ice cloud discoveries, combined with monitoring the seasonal behaviors and time evolution throughout Cassini’s 13-year mission tenure. A significant advance by CIRS was the realization that co-condensing chemical compounds can account for many of the CIRS-observed stratospheric ice cloud spectral features, especially for some that were previously puzzling, even though some of the observed spectral features are still not well understood. Relevant laboratory transmission spectroscopy efforts began just after the Voyager encounters, and have accelerated in the last few years due to new experimental efforts aimed at simulating co-condensed ices in Titan’s stratosphere. This review details the current state of knowledge regarding the organic ice clouds in Titan’s stratosphere, with perspectives from both observational and experimental standpoints.

Astronomy↗
NASA NTRS2018

Organic Ices in Titan's Stratosphere

Titan’s stratospheric ice clouds are by far the most complex of any observed in the solar system, with over a dozen organic vapors condensing out to form a suite of pure and co-condensed ices, typically observed at high winter polar latitudes. Once these stratospheric ices are formed, they will diffuse throughout Titan’s lower atmosphere and most will eventually precipitate to the surface, where they are expected to contribute to Titan’s regolith. Early and important contributions were first made by the InfraRed Interferometer Spectrometer (IRIS) on Voyager 1, followed by notable contributions from IRIS’ successor, the Cassini Composite InfraRed Spectrometer (CIRS), and to a lesser extent, from Cassini’s Visible and Infrared Mapping Spectrometer (VIMS) and the Imaging Science Subsystem (ISS) instruments. All three remote sensing instruments made new ice cloud discoveries, combined with monitoring the seasonal behaviors and time evolution throughout Cassini’s 13-year mission tenure. A significant advance by CIRS was the realization that co-condensing chemical compounds can account for many of the CIRS-observed stratospheric ice cloud spectral features, especially for some that were previously puzzling, even though some of the observed spectral features are still not well understood. Relevant laboratory transmission spectroscopy efforts began just after the Voyager encounters, and have accelerated in the last few years due to new experimental efforts aimed at simulating co-condensed ices in Titan’s stratosphere. This review details the current state of knowledge regarding the organic ice clouds in Titan’s stratosphere, with perspectives from both observational and experimental standpoints.

C. M. Anderson↗
NASA NTRS2020

Dual Anion-Cation Crosslinked Poly(ionic liquid) Composite Membranes for Enhanced CO2 Separation

Herein, we propose a strategy of developing novel dual anionic-cationic crosslinked poly(IL)-IL composite membranes via a photopolymerization method for enhanced CO2 separations. These are the first examples of dually photopolymerized anionic-cationic poly(IL)-IL composite systems, in which the backbones of poly(IL)s feature both pendant anions and cations without any mobile counterions unlike poly(IL) reported so far in the literature. A new type of dual photopolymerizable anionic-cationic IL (DIL) monomer having methacrylate functional group tethered with highly delocalized sulfonimide anion (–SO2–N(-)–SO2–C7H7) and a vinylimidazolium counterion ([C4(vim)](+)) was successfully synthesized and photopolymerized with four distinct amounts of free IL with a structurally analogous cation ([C4(mim)][Tf2N]) and 20 wt% PEGDA crosslinker, offering novel composite matrices. Further, the structure-property relationships as well as gas separation behaviors of the four newly developed dual anioniccationic poly(IL)-IL composite membranes were extensively characterized by FT-IR, DSC, and XRD. All of the newly developed dual anionic-cationic poly(IL)-IL composite membranes displayed outstanding permselectivites for CO2/CH4, CO2/N2, and CO2/H2 gas pairs together with reasonable CO2 permeabilities. As a result, all the dual anionic-cationic poly(IL)-IL composite membranes outperformed the common poly(IL)-IL systems in the upper bound limit plots with best CO2 permeability of 40 barrer and CO2/CH4 permselectivity of 85. This study may pave a new platform to explore countless potential poly(IL)-IL composites for selective separation of CO2 from flue gas, natural gas, and syngas streams.

Irshad Kammakakam↗
NASA NTRS2018

Organic Ices in Titan’s Stratosphere

Titan’s stratospheric ice clouds are by far the most complex of any observed in the solar system, with over a dozen organic vapors condensing out to form a suite of pure and co-condensed ices, typically observed at high winter polar latitudes. Once these stratospheric ices are formed, they will diffuse throughout Titan’s lower atmosphere and most will eventually precipitate to the surface, where they are expected to contribute to Titan’s regolith. Early and important contributions were first made by the InfraRed Interferometer Spectrometer (IRIS) on Voyager 1, followed by notable contributions from IRIS’ successor, the Cassini Composite InfraRed Spectrometer (CIRS), and to a lesser extent, from Cassini’s Visible and Infrared Mapping Spectrometer (VIMS) and the Imaging Science Subsystem (ISS) instruments. All three remote sensing instruments made new ice cloud discoveries, combined with monitoring the seasonal behaviors and time evolution throughout Cassini’s 13-year mission tenure. A significant advance by CIRS was the realization that co-condensing chemical compounds can account for many of the CIRS-observed stratospheric ice cloud spectral features, especially for some that were previously puzzling, even though some of the observed spectral features are still not well understood. Relevant laboratory transmission spectroscopy efforts began just after the Voyager encounters, and have accelerated in the last few years due to new experimental efforts aimed at simulating co-condensed ices in Titan’s stratosphere. This review details the current state of knowledge regarding the organic ice clouds in Titan’s stratosphere, with perspectives from both an observational and experimental standpoint.

Ices↗
NASA NTRS1996

The Visual and Infrared Mapping Spectrometer for Cassini

The Visual and Infrared Mapping Spectrometer (VIMS) is a remote sensing instrument developed for the Cassini mission to Saturn by an international team representing the national space agencies of the United States, Italy, and France. A dual imaging spectrometer, VMS' unique design consists of two optical systems boresighted and operating in tandem, coordinated by a common electronics unit.

imaging↗
NASA NTRS2019

Follow-on studies using the Voyager spacecraft thermal model

The 42-year-old Voyager mission, now named the Voyager Interstellar Mission (VIM) is operating long beyond its design life. In 2012, Voyager 1 crossed the heliopause into interstellar space and Voyager 2 made the same transit in November 2018. Due to declining power output from the Radioisotope Thermoelectric Generators (RTGs) the Science and Flight Operations teams continue to make difficult choices in terms of managing both the power and thermal margins to preserve critical science observations and maintain the health of the two spacecraft. A previous paper, “Creating a Voyager Thermal Model 39 Years Into the Flight Mission, Along With Model Correlation and Application” described how a thermal model of these 1977 spacecraft was developed and correlated without many design artifacts and with limited temperature telemetry. This paper describes how the thermal model has been used to establish an Allowable Flight Temperature (AFT) limit for hydrazine propellant in the propulsion subsystem to minimize the risk of freezing. Voyager 2 temperatures have already descended to this limit in the vicinity of the Roll thruster propellant lines. The Flight Operations team has investigated several ways of detecting propellant freezing based on analysis and trending of thruster performance telemetry. In addition, the Voyager thermal model is being used to predict the spacecraft response to possible changes in power state. These changes could involve turning off outboard science instruments and/or their heaters to increase power margin and hence power dissipation inside the spacecraft bus (i.e. in Bay 7, where the power regulation electronics are located). Changes might also be made to turn on or off other loads inside the bus to more effectively heat the coldest propellant lines.

Medina, Enrique↗
NASA NTRS2019

Follow-on studies using the Voyager spacecraft thermal model

The 42-year-old Voyager mission, now named the Voyager Interstellar Mission (VIM) is operating long beyond its design life. In 2012, Voyager 1 crossed the heliopause into interstellar space and Voyager 2 made the same transit in November 2018. Due to declining power output from the Radioisotope Thermoelectric Generators (RTGs) the Science and Flight Operations teams continue to make difficult choices in terms of managing both the power and thermal margins to preserve critical science observations and maintain the health of the two spacecraft. A previous paper, “Creating a Voyager Thermal Model 39 Years Into the Flight Mission, Along With Model Correlation and Application” described how a thermal model of these 1977 spacecraft was developed and correlated without many design artifacts and with limited temperature telemetry. This paper describes how the thermal model has been used to establish an Allowable Flight Temperature (AFT) limit for hydrazine propellant in the propulsion subsystem to minimize the risk of freezing. Voyager 2 temperatures have already descended to this limit in the vicinity of the Roll thruster propellant lines. The Flight Operations team has investigated several ways of detecting propellant freezing based on analysis and trending of thruster performance telemetry. In addition, the Voyager thermal model is being used to predict the spacecraft response to possible changes in power state. These changes could involve turning off outboard science instruments and/or their heaters to increase power margin and hence power dissipation inside the spacecraft bus (i.e. in Bay 7, where the power regulation electronics are located). Changes might also be made to turn on or off other loads inside the bus to more effectively heat the coldest propellant lines. Many of these changes have been or will be tested first on Voyager 1 which has more power margin and does not have the power matrix commanding issues experienced on Voyager 2. Ultimately this assessment may assist the Voyager project in making decisions on the order in which science instruments are permanently turned off.

Medina, Enrique↗
NASA NTRS2022

Western Montana Ecological Forecasting II: Enhancing Habitat Suitability Modeling of Mustelid Species and Contaminant Monitoring in Northern Montana Using NASA Earth Observations

Environmental contaminants in aquatic ecosystems threaten both human and ecosystem health. Western Montana’s rivers possess great economic and ecological value, yet the status of contaminants in these systems can be unclear. Contaminants such as brominated flame-retardants, heavy metals, and pharmaceuticals negatively affect ecosystem health by traveling through the food chain and bioaccumulating in apex predators. Exposure to these contaminants can result in neurological, endocrine, and reproductive impairments in wildlife and humans. American mink (Neovison vison) and North American river otter (Lontra canadensis) have a predominantly aquatic diet and serve as reliable indicator species of environmental health. Working Dogs for Conservation (WD4C) uses detection dogs to locate scat samples of these species which are assessed for contaminants by the Virginia Institute of Marine Science (VIMS). With Software for Assisted Habitat Modeling (SAHM), the team generated current (2013-2020) and projected (2021-2040) habitat suitability models for mink and otter utilizing NASA Earth observations from Terra Moderate Resolution Imaging Spectroradiometer (MODIS), Global Precipitation Measurement Integrated Multi-Satellite Retrievals for GPM (GPM IMERG), Shuttle Radar Topography Mission (SRTM), and Soil Moisture Active Passive (SMAP). The habitat suitability maps’ study region encompassed Flathead National Forest and Blackfeet Indian Reservation. Additionally, the team created site accessibility and precipitation anomaly maps that display the viability of survey locations. The current habitat suitability models performed well (AUC-PR=0.88). The most important predictor variables for suitable habitat were distance to rivers, elevation, and land cover. These end products will further inform WD4C survey site selection and contaminant monitoring.

Chelsea Morton↗