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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Prolonged triboluminescence in clays and other minerals

Samples of various clays and minerals were ground or fractured and monitored with a liquid scintillation spectrometer in order to obtain triboluminescent decay curves. Kaolinite samples displayed several million counts/min after grinding, with a surface area emission estimated at tens of billions of photons/sq cm of surface. The photon production rates varied with the origin of the sample, and kaolinite continually yielded higher production rates than bentonite. The addition of water to the samples slightly increased the count rate of emitted light, while the addition of the fluorescent molecule substance tryptofan significantly enhanced the count rate. Freezing smears of kaolinite and montmorillonite in liquid nitrogen and in a salt ice mixture also induced triboluminescence in the montmorillonite. A possible connection between powdery triboluminescent materials formed in mining industries and respiratory disorders among miners is suggested.

Lahav, N.↗
NASA NTRS1988

Mass accommodation coefficient measurements for HNO3, HCl and N2O5 on water, ice and aqueous sulfuric acid droplet surfaces

Preliminary results are reported of the direct measurement of accommodation coefficients for HNO3, N2O5 and HCl on water drops, aqueous sulfuric acid drops and ice particles. The heterogeneous chemistry of these species together with ClONO2 has been implicated in the ozone depletion observed in the Antarctic stratosphere during the spring in the last eight years. The most plausible chemical mechanism involves the removal of nitrogen oxide species via condensation on ice particles in polar stratospheric clouds resulting in a increase in the active chlorine species responsible for the ozone depletion. The observation of low NO2 and high ClO densities in the Antarctic stratosphere last summer appear to be consistent with such a mechanism.

Worsnop, Douglas↗
NASA NTRS2000

Organic Matter in the Outer Solar System

Many solid bodies in the outer Solar System are covered with ices of various compositions, including water, carbon dioxide, methane, nitrogen, and other molecules that are solid at the low temperatures that prevail there. These ices have all been detected by remote sensing observations made with telescopes on Earth, or more recently, spacecraft in orbit (notably Galileo at Jupiter). The data also reveal other solid materials that could be minerals or complex carbon-bearing organic molecules. A study in progress using large ground-based telescopes to acquire infrared spectroscopic data, and laboratory results on the optical properties of complex organic matter, seeks to identify the non-icy materials on several satellites of Saturn, Uranus, and Neptune. The work on the satellites of Saturn is in part preparatory to the Cassini spacecraft investigation of the Saturn system, which will begin in 2004 and extend for four years.

Cruiskshank, Dale P.↗
NASA NTRS1992

Secondary electron yields of solar system ices

The secondary electron yields of H2O, CO2, NH3, and CH3OH ices have been measured as a function of electron beam energy in the 2- to 30-keV energy range. The ices were produced on a liquid-nitrogen-cooled cold finger and transferred under vacuum to a SEM where the yield measurements were made. The imaging capabilities of the SEM provide a means of correlating the yield measurements with the morphology of the ices and are also used to monitor charging effects. The yields were determined by measuring the amplified current from a secondary electron detector and calibrating this current signal with the amplified current signal from samples of metals with known secondary electron yields. Each of the measured yields is found to decrease with an increase in energy in the 2- to 30-keV range. Estimates are given for the maximum secondary electron yield Y(max) of each ice and the energy at which this maximum yield occurs. Implications for the charging of solar system ice grains are discussed.

Suszcynsky, David M.↗
NASA NTRS2018

The Photochemistry of Purine in Ice Analogs Relevant to Dense Interstellar Clouds

The aromatic nitrogen heterocyclic compound purine is the core structural framework of many important biomolecules, particularly nucleobases. Purine and purine derivatives have been observed in carbonaceous chondrites, and it has been hypothesized that the exogenous delivery of these compounds, along with many other biologically relevant compounds, may have played a role in the emergence of life. Numerous experiments in our laboratory have demonstrated that the nucleobases used by life to encode genetic material could have been produced abiotically under astrophysically relevant conditions. Specically, the UV photoprocessing of pyrimidine and purine in simple ices of astrophysical interest has resulted in the production of all five biological nucleobases, namely, uracil (RNA), cytosine (RNA and DNA), thymine (DNA), adenine (RNA and DNA), and guanine (RNA and DNA). Additionally, follow-up work has examined the photochemistry of pyrimidine in more complex astrophysical ice mixtures to better understand the formation of these compounds under realistic conditions. In this work, we examine the photochemistry of purine in more complex ices of astrophysical interest and compare our results with those from simpler ice mixtures. We also examine the effects of competing parallel synthesis of organic compounds in the ices (unrelated to purine). Finally, we discuss the astrophysical and astrobiological implications of our findings.

Molecular Processes↗
NASA NTRS2018

The Photochemistry of Purine in Ice Analogs Relevant to Dense Interstellar Clouds

The aromatic nitrogen heterocyclic compound purine is the core structural framework of many important biomolecules, particularly nucleobases. Purine and purine derivatives have been observed in carbonaceous chondrites, and it has been hypothesized that the exogenous delivery of these compounds, along with many other biologically relevant compounds, may have played a role in the emergence of life. Numerous experiments in our laboratory have demonstrated that the nucleobases used by life to encode genetic material could have been produced abiotically under astrophysically relevant conditions. Specifically, the UV photoprocessing of pyrimidine and purine in simple ices of astrophysical interest has resulted in the production of all five biological nucleobases, namely, uracil (RNA), cytosine (RNA and DNA), thymine (DNA), adenine (RNA and DNA), and guanine (RNA and DNA). Additionally, follow-up work has examined the photochemistry of pyrimidine in more complex astrophysical ice mixtures to better understand the formation of these compounds under realistic conditions. In this work, we examine the photochemistry of purine in more complex ices of astrophysical interest and compare our results with those from simpler ice mixtures. We also examine the effects of competing parallel synthesis of organic compounds in the ices (unrelated to purine). Finally, we discuss the astrophysical and astrobiological implications of our findings.

Astrobiology↗
NASA NTRS1980

Growth of ice discs from the vapor and the mechanism of habit change of ice crystals

Ice crystals nucleated on a liquid nitrogen cooled glass fiber grow first as thin disks which subsequently transform to plates and columns as they thicken and extend to regions of higher supersaturation. Crystals are often found to be dislocation-free, which suggests that growth results from surface nucleation, the habit depending on preferential nucleation in an adsorbed multilayer on basal or prism face.

Keller, V. W.↗
NASA NTRS2001

Decoding the Domino: The Dark Side of Iapetus

We present new spectra of the leading and trailing hemispheres of Iapetus from 2.4 to 3.8 micron. We have combined the leading hemisphere spectra with previous observations by others to construct a composite spectrum of the dark side (leading) hemisphere from 0.3 to 3.8 gm. We review attempts to deduce the composition of the dark material from previously available spectrophotometry. None of them (numbering more than 20 million!) leads to a synthetic spectrum that matches the new data. An intimate mixture of water ice, amorphous carbon and a nitrogen-rich organic compound (modeled here as Triton tholin) can fit the entire composite dark side spectrum. Observations in this spectral region have not revealed this mix of material on any other object observed thus far. We propose that this dark material may have originated on Titan, where atmospheric photochemistry has been producing nitrogen-rich organic compounds for 4.5 GY.

Owen, Tobias C.↗
NASA NTRS2010

Possible Catalytic Effects of Ice Particles on the Production of NOx by Lightning Discharges

One mechanism by which NO(x) is produced in the atmosphere is heating in lightning discharge channels. Since most viable proposed electrification mechanisms involve ice crystals, it is reasonable to assume that lightning discharge channels frequently pass through fields of ice particles of various kinds. We address the question of whether ice crystals may serve as catalysts for the production of NO(x) by lightning discharges. If so, and if the effect is large, it would need to be taken into account in estimates of global NO(x) production by lightning. In this study, we make a series of plausible assumptions about the temperature and concentration of reactant species in the environment of discharges and we postulate a mechanism by which ice crystals are able to adsorb nitrogen atoms. We then compare production rates between uncatalyzed and catalytic reactions at 2000 K, 3000 K, and 4000 K. Catalyzed NO production rates are greater at 2000 K, whereas uncatalyzed production occurs most rapidly at 4000 K. 2010

Source record↗
NASA NTRS1991

Paleobiomarkers and defining exobiology experiments for future Mars experiments

Mars is a cold, dry planet with an oxidizing surface bombarded by ultraviolet and ionizing radiation, making prospects for an extant Mars biota bleak. Yet, it is suggested that early Earth and early Mars were similar enought that life may have evoled on Mars. If life did evolve on Mars, what evidence for its existence might we find? What constitutes a Martian paleobiomarker, and how can we distinguish such a marker from abiotically produced substances? The topics studied to answer this question include carbon and nitrogen cycling, as well as the stability and relative abundance of their intermediates in microbially dominated ecosystems. The microbially dominated ecosystems studied are the crytoendolithic microbial community living within sand rocks, the endoevaporite microbial community living inside salt crystals, and the microbial communities living beneath perennially ice-covered lakes and hypersaline ponds. The nitrogen cycle of these communities ranges from simple, where only assimilation occurs, to the more complex, where a complete cycle occurs. The carbon cycle of these communities appears to be complete.

Mancinelli, R. L.↗
DOE OSTI2024

Marine aerosol generation experiments in the High Arctic during summertime

The rapidly warming Arctic has transitioned to thinner sea ice which fractures, producing leads. Few studies have investigated Arctic sea spray aerosol (SSA) produced from open ocean, leads, and melt ponds, which vary in salinity and organic and microbial community composition. A marine aerosol reference tank was deployed aboard an icebreaker to the Arctic Ocean during August–September 2018 to study SSA generated from locally collected surface waters. Aerosol generation experiments were carried out using water collected from the marginal ice zone, a human-made hole in sea ice near the North Pole, and both lead and melt pond water during an ice floe drift period. Salinity, chlorophyll a, organic carbon, nitrogen, and microbial community composition were measured. Eukaryotic plankton and bacterial abundance were elevated in experimental water from the marginal ice zone, but the relative contributions from major eukaryotic taxonomic groups varied little across the experiments. The chemical composition of individual SSA particles was analyzed using Raman microspectroscopy and computer-controlled scanning electron microscopy with energy-dispersive X-ray spectroscopy. Individual sea salt aerosol, primary organic aerosol, and mineral dust particles were observed. Sea salt aerosol constituted 44–95% of individual submicrometer and 68–100% of supermicrometer particles, by number, generated during each experiment. Carbon was detected in 85%, by number, of the individual sea salt particles, with visible organic coatings. Carbohydrates were detected in 72% of particles, by number, with smaller contributions from long-chain fatty acids (13%) and siliceous material (15%). SSA generated from melt pond water contained only long-chain fatty acids and siliceous material. Quantification of the ice-nucleating activity showed that locally produced SSA may define the High Arctic background ice-nucleating particle population, but cannot account for the peak atmospheric concentrations observed. As the Arctic warms, the increasing SSA emissions have a complex dependence on changing biological and physical processes.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1985

Evolution of Titan's coupled ocean-atmosphere system and interaction of ocean with bedrock

A recent model for the surface state of Titan proposes a liquid ethane-methane-molecular nitrogen layer of order one kilometer thick which because of stratospheric methane photolysis has become increasingly ethane-rich with time. The interaction of such an ocean with the underlying 'bedrock' of Titan (assumed to be water-ice or ammonia hydrate) and with the primarily nitrogen atmosphere is explored. It is concluded that although modest exchange of oceanic hydrocarbons with enclathrated methane in the bedrock can in principle occur, it is unlikely for reasonable regolith depths. The surprisingly high solubility of water-ice in liquid methane implies that topographic features on Titan of order 100 meters in height can be eroded away on a time scale of one-billion years. The large solubility difference of N2 in methane versus ethane implies that the ocean composition is a strong determinant of atmospheric pressure; a simple radiative model of the Titan atmosphere is employed to demonstrate that significant surface pressure and temperature changes can occur as the oceanic composition evolves with time.

Lunine, J. I.↗
NASA NTRS1989

Analysis of particulates of comet nucleus samples: Possible use of olivine as indicator phase

The electron microprobe is a proven instrument for particulate analysis and modifications are possible for in situ analysis of particulates in ice at temperatures near that of liquid nitrogen. Present sample requirements allow for polished samples with 0.25 x 0.25 dimensions to be maintained in the sample chamber of a modern electron probe (CAMECA SX-50) at a temperature of -150 C; larger samples are possible but at higher temperatures as determined by thermal conductivity. The major problem is transport and insertion of samples into the instrument through vacuum interlocks. The manufacturer of the above microprobe has designed an exchange mechanism to allow storage and transport of samples previously prepared for their sample holder which attaches to their instrument allowing extraction and insertion of samples while maintaining -150 C temperature. An important test will be the capability of preparing polished surfaces of an ice-particulate sample without loss of particles and at low temperatures. While thin sections of water ice are routine, these are not examined for particulate material and are prepared at temperatures easily obtained in room-size volumes. Anticipated problems include rounding of small grains in the relatively soft ice matrix and the technical problem of dry polishing.

Steele, I. M.↗
NASA NTRS2014

Preservation of a Preglacial Landscape Under the Center of the Greenland Ice Sheet

Continental ice sheets typically sculpt landscapes via erosion; under certain conditions, ancient landscapes can be preserved beneath ice and can survive extensive and repeated glaciation. We used concentrations of atmospherically produced cosmogenic beryllium-10, carbon, and nitrogen to show that ancient soil has been preserved in basal ice for millions of years at the center of the ice sheet at Summit, Greenland. This finding suggests ice sheet stability through the Pleistocene (i.e., the past 2.7 million years). The preservation of this soil implies that the ice has been non-erosive and frozen to the bed for much of that time, that there was no substantial exposure of central Greenland once the ice sheet became fully established, and that preglacial landscapes can remain preserved for long periods under continental ice sheets

Preservation↗
NASA NTRS2013

Compositions of the Surfaces of Pluto and its Satellites

The information we have on the chemical compositions of the surfaces of Pluto and Charon has been obtained from Earth-based near-infrared spectroscopy. These bodies are seen in diffusely scattered sunlight upon which absorption bands diagnostic of specific ices are superimposed. Identified so far on Pluto are molecular nitrogen (N2), methane (CH4), carbon monoxide (CO), and ethane (C2H6), all in the frozen state. Charon has the clear spectral signature of H2O ice in the crystalline phase, plus an absorption band near 2.2 microns identified as a hydrated form of NH3. No diagnostic spectra of Pluto's other satellites are currently available. A fraction of Pluto's CH4 is dissolved in solid N2, which is in the hexagonal beta-phase. When a small concentration of CH4 exists in a N2 crystalline matrix, its absorption bands are shifted in wavelength by a small but detectable amount. Indeed the shifting of the CH4 bands is diagnostic of a host matrix. In the case of Pluto, the N2 band (2.148 microns) itself is detected, but for other trans-Neptunian objects where the N2 band cannot be seen, the shifted CH4 bands demonstrate the presence of N2 or (less likely) some other spectrally neutral and transparent matrix material (e.g., Ar). The absence of detectable CO2 and H2O ices on Pluto, while they are clearly present on the otherwise very similar Triton, is noteworthy. The ices of Pluto distributed non-uniformly across its surface, and the distribution shows long-term (decadal) changes. Both seasonal and secular changes may be occurring through transport across the surface as a result of changing temperature, and by seasonal changes in the vapor pressure equilibrium of the ice with the tenuous and variable atmosphere. Models of the photochemistry of the surface ices and the atmosphere of Pluto predict the presence of several materials not yet detected; the most abundant photoproducts are expected to be C2H2, C4H2, HCN, C2H6; HCN has been detected on Triton. Both Pluto and Charon have surface components in addition to the detected ices. These materials of presently unknown composition serve to reduce the albedos of both bodies below that expected for pure ices, and in the case of Pluto impart a yellow-brown coloration; the color of Charon is more nearly neutral. It is generally thought that the non-ice components are more refractory than the ices and that they may be complex carbonaceous materials derived from the ultraviolet and charged particle processing of the surface ices. Minerals are also plausible candidates for the non-ice fraction. The refractory colored components may constitute bedrock upon which variable amounts of the ices are alternately deposited and evaporated as the seasons change. Water ice is expected to be a component of the bedrock, although it has not yet been reliably identified.

Pluto↗
NASA NTRS1992

Numerical study of low-current steady arcs

The development of a high-efficiency CW YLF laser doped with Er,Tm,Ho: and featuring a strongly focusing resonator that collects a high density of pump power on the active crystal is described. The emission is investigated at 2.06 microns and a tuning range both at liquid-nitrogen (77 K) and at dry-ice (210 K) temperature. The noise characteristics and the long-term power stability of the laser is studied with an eye to employing this source for high-resolution spectroscopy in the 2-micron wavelength region. The detection of several absorption lines of NH3 at low pressure is described. The output power of the laser as a function of the power impinging on the crystal for different transmission of the output mirror is illustrated. The best result obtained is 1.46 W output for 3.2 W of argon pump. The minimum threshold achieved is 3.5 mW with a 1-percent transmission mirror. It is concluded that it is possible to develop a highly efficient Ho:YLF laser featuring low noise and sufficient tunability for high-resolution spectroscopy in the 2-micron region.

Kim, S. C.↗
NASA NTRS1995

The Plausibility of Boiling Geysers on Triton

A mechanism is suggested and modeled whereby there may be boiling geysers on Triton. The geysers would be of nitrogen considering that Voyager detected cryovolcanic activity, that solid nitrogen conducts heat much less than water ice, and that there is internal heat on Triton.

Triton planetary geology geysers↗