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DOE OSTI2024

Zeolite-promoted platinum catalyst for efficient reduction of nitrogen oxides with hydrogen

Internal combustion engine fueled by carbon-free hydrogen (H 2 -ICE) offers a promising alternative for sustainable transportation. Herein, we report a facile and universal strategy through the physical mixing of Pt catalyst with zeolites to significantly improve the catalytic performance in the selective catalytic reduction of nitrogen oxides (NO x ) with H 2 (H 2 -SCR), a process aiming at NO x removal from H 2 -ICE. Via the physical mixing of Pt/TiO 2 with Y zeolite (Pt/TiO 2 + Y), a remarkable enhancement of NO x reduction activity and N 2 selectivity was simultaneously achieved. The incorporation of Y zeolite effectively captured the in-situ generated water, fostering a water-rich environment surrounding the Pt active sites. This environment weakened the NO adsorption while concurrently promoting the H 2 activation, leading to the strikingly elevated H 2 -SCR activity and N 2 selectivity on Pt/TiO 2 + Y catalyst. This study provides a unique, easy and sustainable physical mixing approach to achieve proficient heterogeneous catalysis for environmental applications.

36 MATERIALS SCIENCE↗

NASA NTRS2006

Laboratory experiments on interstellar ice analogs: The sticking and desorption of small physisorbed molecules

Molecular oxygen and nitrogen are difficult to observe since they are infrared inactive and radio quiet. The low O2 abundances found so far combined with general considerations of dense cloud conditions suggest molecular oxygen is frozen out at low temperatures (< 20 K) in the shielded inner regions of cloud cores. In solid form O2 and N2 can only be observed as adjuncts within other ice constituents, like CO. In this work we focus on fundamental properties of N2 and O2 in CO ice-gas systems, e.g. desorption characteristics and sticking probabilities at low temperatures for different ice morphologies.

Fuchs, G. W.↗

NASA NTRS2003

LSPECS: A Proposed Robotic Astronomy Mission to the Lunar South Polar Regions

This paper outlines a possible mission to emplace a robotic infrared/submillimeter wave interferometer array near the lunar south pole. This region has now been investigated by the Clementine and Lunar Prospector missions, and by Earth-based radar, and its topography and thermal environment are fairly well-known. The area would be exceptionally suitable for infrared/submillimeter astronomy because of the continually low temperatures, approaching that of liquid nitrogen (77K) in some places. The presence of ice has been inferred independently from Clementine and Lunar Prospector, providing another incentive for a south polar mission. A submillimeter spaceborne interferometer mission, Submillimeter Probe of the Evolution of the Cosmic Structure (SPECS) has been proposed by John Mather and others, covering the 40 - 500 micron region with 3 formation flying telescopes. The present paper proposes a lunar adaptation of the SPECS concept, LSPECS. This adaptation would involve landing 4 telescopes on the area north of Shackleton crater at zero degrees longitude. This is in nearly year round darkness but is continually radar visible from Earth. The landed payload of LSPECS would include a telerobotic rover, 4 three meter submm telescopes, a solar power array to be emplaced on the continually sunlit north rim of Shackleton crater, and an S-band antenna for data relay to Earth. Operation without the use of expendable cryogenics for cooling might be possible, trading long exposure time for instrument temperatures above that of liquid helium. The LSPECS would permit long-term study of an extremely wide range of cosmic and solar system phenomena in the southern celestial hemisphere. For complete sky coverage, a similar installation near the north pole would be required. The LSPECS site would also be suitable other types of observation, such as optical interferometry or centimeter wavelength radio astronomy. The lunar south pole is also of great interest because of its extensive ice deposits, which may represent cometary infall with pre-biotic compounds.

Lowman, Paul D., Jr.↗

DOE OSTI2021

Transport and chemistry of isoprene and its oxidation products in deep convective clouds

Deep convective clouds can transport trace gases from the planetary boundary layer into the upper troposphere where subsequent chemistry may impact aerosol particle formation and growth. In this modelling study, we investigate processes that affect isoprene and its oxidation products injected into the upper troposphere by an isolated deep convective cloud in the Amazon. We run a photochemical box model with coupled cloud microphysics along hundreds of individual air parcel trajectories sampled from a cloud-resolving model simulation of a convective event. The box model simulates gas-phase chemical reactions, gas scavenging by liquid and ice hydrometeors, and turbulent dilution inside a deep convective cloud. The results illustrate the potential importance of gas uptake to anvil ice in regulating the intensity of the isoprene oxidation and associated low volatility organic vapour concentrations in the outflow. Isoprene transport and fate also depends on the abundance of lightning-generated nitrogen oxide radicals (NO x = NO + NO 2 ). If gas uptake on ice is efficient and lightning activity is low, around 30% of the boundary layer isoprene will survive to the cloud outflow after approximately one hour of transport, while all the low volatile oxidation products will be scavenged by the cloud hydrometeors. If lightning NO x is abundant and gas uptake by ice is inefficient, then all isoprene will be oxidised during transport or in the immediate outflow region, while several low volatility isoprene oxidation products will have elevated concentrations in the cloud outflow. Reducing uncertainties associated with the uptake of vapours on ice hydrometeors, especially HO 2 and oxygenated organics, is essential to improve predictions of isoprene and its oxidation products in deep convective outflows and their potential contribution to new particle formation and growth.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1992

Triton - Voyager's finale

The investigation of the Neptunian satellite Triton by the Voyager 2 is described with interpretations of the object's nature and composition. The orbit, seasonal cycle, and southern-hemisphere solstice are described, and the composition of the satellite is discussed. Triton's mass and radius are known, and the objects is made up of about 70 percent rock and organics and 30 percent ice by mass. Triton's interior is warm and geologically active considering its distance from the sun, and large amounts of frozen methane and nitrogen are theorized to contribute to the object's high reflectivity. Also noted in the Voyager color images are creeping ice, cryogenic lava, and dark streaks on the south polar cap from nitrogen gas leaks driven by a type of greenhouse effect. Triton represents a class of satellite that has not been observed previously: a moon-sized body in a retrograde inclined orbit from the class of objects that coalesced to form Neptune.

Brown, R. H.↗

NASA NTRS1999

Energetic Charged Particle Component or the NO(y) Budget of the Polar Middle Atmosphere

Analysis of nitrates measured in polar ice cap snow at a high resolution shows large variations in the nitrates. It has been shown that the nitrate signal may contain a signature of solar activity [Zeller and Dreschhoff, 19951. Reactive odd nitrogen production associated with solar particle events (SPEs) and auroral activity may be a source of some of the nitrate anomalies observed in the polar ice caps. Periods of large SPEs can lead to a production of polar atmospheric odd nitrogen in excess of the ambient sources in the polar stratosphere and mesosphere, and may leave a large nitrate signal stratified in the polar ice cap. Auroral electrons and photoelectrons produce odd nitrogen in the thermosphere, some of which may be transported to the polar (>50 degrees) mesosphere and stratosphere. Sources of odd nitrogen in the polar middle atmosphere associated with SPEs, galactic cosmic rays, and auroral electron precipitation have been quantified. The relative contributions by the energetic particles sources to the Noy budget of the polar middle atmosphere (from tropopause to 50 km, from 50 degrees to 90 degrees latitude) are compared with the nitrates observed in the polar ice sheets.

Vitt, F. M.↗

DOE OSTI2020

Observations for Model Intercomparison Project (Obs4MIPs): status for CMIP6

The Observations for Model Intercomparison Project (Obs4MIPs) was initiated in 2010 to facilitate the use of observations in climate model evaluation and research, with a particular target being the Coupled Model Intercomparison Project (CMIP), a major initiative of the World Climate Research Programme (WCRP). To this end, Obs4MIPs (1) targets observed variables that can be compared to CMIP model variables; (2) utilizes dataset formatting specifications and metadata requirements closely aligned with CMIP model output; (3) provides brief technical documentation for each dataset, designed for nonexperts and tailored towards relevance for model evaluation, including information on uncertainty, dataset merits, and limitations; and (4) disseminates the data through the Earth System Grid Federation (ESGF) platforms, making the observations searchable and accessible via the same portals as the model output. Taken together, these characteristics of the organization and structure of obs4MIPs should entice a more diverse community of researchers to engage in the comparison of model output with observations and to contribute to a more comprehensive evaluation of the climate models. At present, the number of obs4MIPs datasets has grown to about 80; many are undergoing updates, with another 20 or so in preparation, and more than 100 are proposed and under consideration. A partial list of current global satellite-based datasets includes humidity and temperature profiles; a wide range of cloud and aerosol observations; ocean surface wind, temperature, height, and sea ice fraction; surface and top-of-atmosphere longwave and shortwave radiation; and ozone (O 3 ), methane (CH 4 ), and carbon dioxide (CO 2 ) products. A partial list of proposed products expected to be useful in analyzing CMIP6 results includes the following: alternative products for the above quantities, additional products for ocean surface flux and chlorophyll products, a number of vegetation products (e.g., FAPAR, LAI, burned area fraction), ice sheet mass and height, carbon monoxide (CO), and nitrogen dioxide (NO 2 ). While most existing obs4MIPs datasets consist of monthly-mean gridded data over the global domain, products with higher time resolution (e.g., daily) and/or regional products are now receiving more attention. Along with an increasing number of datasets, obs4MIPs has implemented a number of capability upgrades including (1) an updated obs4MIPs data specifications document that provides additional search facets and generally improves congruence with CMIP6 specifications for model datasets, (2) a set of six easily understood indicators that help guide users as to a dataset's maturity and suitability for application, and (3) an option to supply supplemental information about a dataset beyond what can be found in the standard metadata. With the maturation of the obs4MIPs framework, the dataset inclusion process, and the dataset formatting guidelines and resources, the scope of the observations being considered is expected to grow to include gridded in situ datasets as well as datasets with a regional focus, and the ultimate intent is to judiciously expand this scope to any observation dataset that has applicability for evaluation of the types of Earth system models used in CMIP.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1991

Infrared observations of small solar system bodies

Infrared reflectance spectra were measured of dark primitive asteroids in the 2 to 5 micron wavelength region. The search was for organic complexes such and CN, CH, and NH in dark material on small bodies in the solar system. A search and study was made of volatiles such as nitrogen, methane, ammonia, and carbon monoxide, both as free ices and hydrates/clathrates, on icy surfaces in the outer solar system, using high resolution spectra obtained with a multichannel cooled grating, infrared spectrometer. An absorption that can be attributed to X-C (triple bond) N in the matrix of dark materials on the primitive asteroids.

Brown, R. H.↗

NASA NTRS1997

A Laboratory Study on the Phase Transition for Polar Stratospheric Cloud Particles

The nucleation and growth of different phases of simulated polar stratospheric cloud (PSC) particles were investigated in the laboratory. Solutions and mixtures of solutions at concentrations 1 to 5 m (molality) of ammonium sulfate, ammonium bisulfate, sodium chloride, sulfuric acid, and nitric acid were supercooled to prescribed temperatures below their equilibrium melting point. These solutions were contained in small diameter glass tubing of volumes ranging from 2.6 to 0.04 ml. Samples were nucleated by insertion of an ice crystal, or in some cases by a liquid nitrogen cooled wire. Crystallization velocities were determined by timing the crystal growth front passages along the glass tubing. Solution mixtures containing aircraft exhaust (soot) were also examined. Crystallization rates increased as deltaT2, where deltaT is the supercooling for weak solutions (2 m or less). The higher concentrated solutions (greater than 3 m) showed rates significantly less than deltaT2. This reduced rate suggested an onset of a glass phase. Results were applied to the nucleation of highly concentrated solutions at various stages of polar stratospheric cloud development within the polar stratosphere.

Teets, Edward H., Jr.↗

NASA NTRS2005

Ion Neutral Mass Spectrometer Measurements from Titan

Introduction: The Ion Neutral Mass Spectrometer (INMS) aboard the Cassini orbiter has obtained the first in situ composition measurements of the neutral densities of molecular nitrogen, methane, argon, and a host of stable carbon-nitrile compounds in its first flyby of Titan. The bulk composition and thermal structure of the moon s upper atmosphere do not appear to be changed since the Voyager flyby in 1979. However, the more sensitive techniques provided by modern in-situ mass spectrometry also give evidence for large-spatial-scale large-amplitude atmospheric waves in the upper atmosphere and for a plethora of stable carbon-nitrile compounds above 1174 km. Furthermore, they allow the first direct measurements of isotopes of nitrogen, carbon, and argon, which provide interesting clues about the evolution of the atmosphere. The atmosphere was first accreted as ammonia and ammonia ices from the Saturn sub-nebula. Subsequent photochemistry likely converted the atmosphere into molecular nitrogen. The early atmosphere was 1.5 to 5 times more substantial and was lost via escape over the intervening 4.5 billion years due to the reduced gravity associated with the relatively small mass of Titan. Carbon in the form of methane has continued to outgas over time from the interior with much of it being deposited in the form of complex hydrocarbons on the surface and some of it also being lost to space.

Waite, J. H., Jr.↗

NASA NTRS2005

Neptune Polar Orbiter with Probes

The giant planets of the outer solar system divide into two distinct classes: the gas giants Jupiter and Saturn, which consist mainly of hydrogen and helium; and the ice giants Uranus and Neptune, which are believed to contain significant amounts of the heavier elements oxygen, nitrogen, and carbon and sulfur. Detailed comparisons of the internal structures and compositions of the gas giants with those of the ice giants will yield valuable insights into the processes that formed the solar system and, perhaps, other planetary systems. By 2012, Galileo, Cassini and possibly a Jupiter Orbiter mission with microwave radiometers, Juno, in the New Frontiers program, will have yielded significant information on the chemical and physical properties of Jupiter and Saturn. A Neptune Orbiter with Probes (NOP) mission would deliver the corresponding key data for an ice giant planet. Such a mission would ideally study the deep Neptune atmosphere to pressures approaching and possibly exceeding 1000 bars, as well as the rings, Triton, Nereid, and Neptune s other icy satellites. A potential source of power would be nuclear electric propulsion (NEP). Such an ambitious mission requires that a number of technical issues be investigated, however, including: (1) atmospheric entry probe thermal protection system (TPS) design, (2) probe structural design including seals, windows, penetrations and pressure vessel, (3) digital, RF subsystem, and overall communication link design for long term operation in the very extreme environment of Neptune's deep atmosphere, (4) trajectory design allowing probe release on a trajectory to impact Neptune while allowing the spacecraft to achieve a polar orbit of Neptune, (5) and finally the suite of science instruments enabled by the probe technology to explore the depths of the Neptune atmosphere. Another driving factor in the design of the Orbiter and Probes is the necessity to maintain a fully operational flight system during the lengthy transit time from launch through Neptune encounter, and throughout the mission. Following our response to the recent NASA Research Announcement (NRA) for Space Science Vision Missions for mission studies by NASA for implementation in the 2013 or later time frame, our team has been selected to explore the feasibility of such a Neptune mission.

Bienstock, Bernard↗

NASA NTRS1988

Antarctic ozone depletion chemistry - Reactions of N2O5 with H2O and HCl on ice surfaces

In a study concerning Antarctic ozone depletion, reactions of dinitrogen pentoxide with water and hydrochloric acid were studied on ice surfaces in a Knudsen cell flow reactor. The N2O5 reacted on ice at 185 K to form condensed-phase nitric acid (HNO3). This reaction may provide a sink for odd nitrogen, NO(x), during the polar winter, a requirement in nearly all models of Antarctic ozone depletion. The reaction of N2O5 on HCl-ice surfaces at 185 K produced gaseous nitryl chloride (ClNO2) and condensed-phase HNO3 and proceeded until all of the HCl within the ice was depleted. The ClNO2 which did not react or condense on ice at 185 K, can be readily photolyzed in the Antarctic spring to form atomic chlorine for catalytic ozone destruction cycles. The other photolysis product, gaseous nitrogen dioxide may be important in the partitioning of NO(x) between gaseous and condensed phases in the Antarctic winter.

Tolbert, Margaret A.↗

NASA NTRS1988

Volatiles on Triton - The infrared spectral evidence, 2.0-2.5 microns

The new IR spectra presented for Triton exhibit the 2.3-micron methane band as well as Cruikshank et al.'s (1984) 2.15-micron spectral band. It is found on the basis of comparisons with methane ice spectra, and laboratory spectra of methane dissolved in liquid nitrogen, that the former band cannot be exclusively due to methane's presence. Also, the strength of the 2.3-micron band does not allow any obvious correlation with the satellite's orbital position in the new data set.

Cruikshank, Dale P.↗

NASA NTRS2002

Side Group Addition to the PAH Coronene by UV Photolysis in Cosmic Ice Analogs

Ultraviolet photolysis of various ice mixtures at low temperature and pressure caused the addition of amino (-NH2), methyl (-CH3), methoxy (-OCH3), and cyano (-CN) functional groups to the polycyclic aromatic hydrocarbon (PAH) coronene (C22H12). The implications of these results for interstellar and meteoritic chemistry are discussed. Previously only simple PAH photo-oxidation had been reported. This work represents the first experimental evidence that ice photochemistry may have contributed to aromatics bearing carbon and nitrogen containing side groups that are detected in primitive meteorites and interplanetary dust particles. Furthermore, these results suggest a wider range of modified PAHs should be expected in interstellar lees and materials predating solar system formation.

Bernstein, Max P.↗

NASA NTRSDate not supplied

NASA 5.2%-Scale High Lift Common Research Model (CRM-HL) Test in the National Transonic Facility (NTF)

Problem: Predicting CL,max and assessing transition, turbulence models, and Reynolds number effect predictions in CFD requires wind tunnel data for comparison. Objective: Expand the CFD validation database by running multiple models designed using the same reference geometry in various wind tunnels around the world. The wind tunnel data and model geometry will be open source to allow for CFD validation use. Approach: Run the NASA 5.2%-scale High Lift Common Research Model (CRM-HL) semi-span model at the National Transonic Facility (NTF). Test the model at chord Reynolds numbers (Rec) between 1.6 million and 30 million and at varying Q/Es to assess Reynolds number effects and aeroelasticity affects on the model, while collecting force and moment, pressure and wing deformation data. Test the model with ice shapes installed on the leading edges. Results: Ran eight model configurations, including four landing, two landing with ice shapes installed, and two takeoff configurations. Ran in air (120°F) and nitrogen operations (-50°F, -180°F and -250°F) at 7 different chord Reynolds numbers. The data compare well with previous tests of the same model at DLR (The Germany Aerospace Center) and the 14- by 22-Foot Subsonic Tunnel (14x22). Significance: Provided valuable high Reynolds number data on a high lift configuration to the worldwide research community. Provide icing data at flight Reynolds number to the research community.

CRM-HL↗

NASA NTRS1994

Recent Advances in Organic Cosmochemistry

The Astrochemistry Laboratory at NASA's Ames Research Center pursues a variety of activities, most of which center around the use of spectroscopy (ultraviolet to far-infrared) for the interpretation of astronomical and meteoritic data. One of our key activities is the study of the chemical and physical properties of cometary, interstellar, and planetary ice analogs and matrix-isolated molecules of astrophysical interest. As a result of these studies it is now known that a significant fraction of the carbon in the interstellar medium (ISM) is in reasonably complex forms, some of which are clearly of interest for exobiology. Examples of compounds known or suspected to be present in space include polycyclic aromatic hydrocarbons (PAHs), microdiamonds, an aliphatic-rich component found in the diffuse interstellar medium, and a variety of molecular species produced by the irradiation of mixed molecular ices in dense clouds. A number of the species produced by irradiation contain nitrogen and appear to offer an additional means of producing some of the amino acids found in meteorites. I will review these complex carbonaceous materials and discuss how they are connected with each other and the organic materials that ultimately ended up as part of our own Solar System. Specific points that will probably be covered include: (1) the composition of the ices in interstellar dense molecular clouds; (2) the more complex organic compounds produced when these ices are irradiated and/or warmed; (3) the detection of microdiamonds in space; (4) the discovery that aliphatic materials may constitute as much as 15% of all the carbon in the diffuse ISM, appears to be present everywhere in the galaxy, and yet seems to be present everywhere in the galaxy, and yet seems to be significantly concentrated towards the center of the galaxy.

Sandford, Scott A.↗

NASA NTRS1976

Production of I-123

Bombarding a cesium heat pipe with high energy particles causes a spallation reaction which produces vapors of Xe-123 and contaminants. The contaminants are removed in a dry ice cold trap while the Xe-123 condenses in a liquid nitrogen trap where it decays.

Blue, J. W.↗

NASA NTRS2005

[Stellar Occultation Studies of Small Bodies in the Outer Solar System: Accomplishments, Status, and Plans]

Bodies residing in the outer solar system exhibit unique physical processes, and some of the lessons learned from them can be applied to understanding what occurred in the outer solar system during its formation and early evolution. Pluto, the largest known Kuiper Belt object (KBO), and its near twin Triton--an ex-KBO that has been captured by Neptune--have nitrogen atmospheres that are in vapor-pressure equilibrium with surface ice. These atmospheres are most sensitively probed from Earth by the technique of Stellar occultations, which can provide the temperature and pressure profiles of these atmospheres at a spatial resolution of a few kilometers. Recent results from occultations show that the surface pressure of Triton's atmosphere has been increasing and that the shape of the atmosphere deviates from its expected spherical figure. With the occultation technique we can also learn the sizes of smaller bodies that have formed in the outer solar system: Charon, the Centaurs, and KBOs. Our proposed program involves identifying occultation candidates, predicting occultations, observing occultations, analysis of the data, and synthesis of the occultation results with other data. The main goals for our proposed work are to (i) further observe occultations by Triton with the objectives of understanding its pressure changes, distortion, and enigmatic thermal structure (ii) determine whether the abrupt drop in Pluto's stellar occultation light curve is caused by a sharp thermal gradient near its surface or by atmospheric haze, (iii) further observations to characterize the potential collapse of Pluto's atmosphere as it recedes from the sun (information that should be of interest to the Pluto-Kuiper Express), ( iv ) determine Charon's radius more accurately than can be done with the mutual events to derive a better estimate of Charon's density, and ( v ) directly determine the size (and albedo) of Centaurs with the goal of more accurately estimating the sizes of KBOS.

Elliott, James↗