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NASA NTRS1995

Quantum yield for carbon monoxide production in the 248 nm photodissociation of carbonyl sulfide (OCS)

Tunable diode laser absorption spectroscopy has been coupled with excimer laser flash photolysis to measure the quantum yield for CO production from 248 nm photodissociation of carbonyl sulfide (OCS) relative to the well-known quantum yield for CO production from 248 nm photolysis of phosgene (Cl2CO2). The temporal resolution of the experiments was sufficient to distinguish CO formed directly by photodissociation from that formed by subsequent S((sup 3)P(sub J)) reaction with OCS. Under the experimental conditions employed, CO formation via the fast S((sup 1)D(sub 2)) + OCS reaction was minimal. Measurements at 297K and total pressures from 4 to 100 Torr N2 + N2O show the CO yield to be greater than 0.95 and most likely unity. This result suggests that the contribution of OCS as a precursor to the lower stratospheric sulfate aerosol layer is somewhat larger than previously thought.

Zhao, Z.↗

NASA NTRS2021

A Short Glossary of Inclusive Language

Words matter—that old adage that many of us may have heard as children, Sticks and stones may break my bones, but words will never hurt me, is a harmful fallacy. In reality, the language we use has tremendous power to alienate, exclude, deride, humiliate, and wound. On the other hand, thoughtful use of language can signal openness, inclusivity, admiration, and celebration, or simply be an expression of empathy and care for our fellow humans. As part of The Oceanography Society (TOS) Justice, Equity, Diversity, and Inclusion Committee’s series of columns in Oceanography, here we provide a glossary of terms that are often used while discussing topics such as race, ethnicity, gender, sexual orientation, and gender identity. It should be explicitly stated that this list is neither definitive nor exhaustive. Indeed, the terms included here are likely heavily influenced by the authors’ own lived experiences and the lenses through which we see the world. Language is a living entity, a fluid social construct subject to rapid changes and overlaid with regional nuances. Indeed, what may be accurate and acceptable terminology for one person may be entirely unacceptable for another. Keeping this in mind, the following glossary is an attempt to group together some of the acronyms and phrases that are most commonly used today in social justice studies and bodies of work and that may have particular relevance to our community of ocean-related scientists, technologists, and stakeholders. We have borrowed heavily from a wide range of excellent existing scholarship and activism and have cited all sources used. We encourage the reader to follow the links to these multimedia resources and, perhaps, use them as teaching and discussion materials with your students, colleagues, and mentees. Finally, it is our hope that this glossary, along with the links provided to more comprehensive definitions and discussions, helps to define terms that you may have heard used, but not understood, and that it will serve to remind us of the power of the words we use in our everyday professional and personal lives. We begin by defining the very words that form the name of our committee: Justice, Equity, Diversity, and Inclusion (JEDI)

Susanne E. Craig↗

NASA NTRS1988

Adhesion scratch testing - A round-robin experiment

Six sets of samples, TiN coated by chemical or physical vapor deposition methods (CVD or PVD) onto cemented carbide or high-speed steel (HSS), and TiC coated by CVD onto cemented carbide have been scratch tested using three types of commercially available scratch adhesion tester. With exception of one cemented carbide set, the reproducibility of the critical loads for any given set with a given stylus is excellent, about + or - 5 percent, and is about + or - 20 percent for different styli. Any differences in critical loads recorded for any given sample set can be attributed to the condition of the stylus (clean, new, etc.), the instrument used, the stylus itself (friction coefficient, etc.), and the sample set itself. One CVD set showed remarkably large differences in critical loads for different styli, which is thought to be related to a mechanical interaction between stylus and coating which is enhanced by a plastic deformability in the film related to the coating microstructure. The critical load for TiN on HSS increases with coating thickness, and differences in frictional conditions led to a systematic variation in the critical loads depending on the stylus used.

Perry, A. J.↗

NASA NTRS1980

Association of flaring X-ray bright points with type III bursts

Using the swept-frequency radio observations obtained at the Clark Lake Radio Observatory and the X-ray photographs taken by the S-054 experiment aboard Skylab, a search has been made for type III bursts associated with X-ray bright point (XBP) flares. Using temporal as well as spatial criteria for the association, four such events are found over a period of 43 days. The time period was selected in such a way that the level of flare and radio activity was low in order to minimize the chance coincidences. The detection of type III bursts from the flaring XBPs is of great interest, since it identifies them with the flare process, of which XBP flares are thought to be the simplest form.

Kundu, M. R.↗

NASA NTRS1986

Fast-shock formation in line-tied magnetic reconnection models of solar flares

In a previous study by the author, an approximately stationary fast shock was tentatively identified in a numerical experiment designed to study line-tied magnetic reconnection. Here the evidence for the occurrence of a stationary fast shock is reexamined, and the previous identification is confirmed. In the numerical experiment, line-tied reconnection is modeled by a configuration which produces two supermagnetosonic outflow jets - one directed upward, away from the photosphere, and one directed downward, toward an arcade of closed magnetic loops tied to the photosphere. The fast shock occurs when the downward-directed jet encounters the obstacle formed by the closed loops. Although the existence of a stationary, or nearly stationary, fast shock is confirmed, the transition from the supermagnetosonic flow region upstream of the shock to the nearly static region downstream of the shock is more complicated than was previously thought. Immediately downstream of the shock, there exists a deflection sheath in which the submagnetosonic flow coming out of the shock is diverted around the region of static closed loops. The MHD jump conditions are used to investigate the characteristics of the fast shock and to show that a stationary shock cannot exist unless accompanied by a deflection sheath. Analysis of the shock's location and dimensions suggests that such fast shocks may contribute to particle acceleration and to thermal condensation in flares.

Forbes, T. G.↗

NASA NTRS1993

The spectral effects of subsolidus reduction of olivine and pyroxene

The surfaces of atmosphereless bodies are subjected to a variety of chemical, thermal, accretionary, and shock processes related to their regolith environment. These processes are responsible for a number of alterations that occur in regoliths. Alterations include particle size commutation, implantation of solar wind gases, formation of agglutinates, spectral darkening, and, in the lunar case, the development of the very strong red continuum slope in the visible and near infrared spectra. A great deal of work has pointed to the role of agglutinates as the principal agent for darkening and reddening the lunar soil. The measures of regolith maturity are strongly linked to the accumulation of agglutinates. Recent work has suggested that the finest fractions of agglutinitic glass are major source of the spectral red slope. In particular, the red slope is most strongly associated with the agglutinitic glasses that are rich in blebs of sub-micron sized metal particles. It is thought that these metal particles, because of their size and scattering efficiently relative to the wavelength of light, are responsible for the red continuum slope. This fine fraction of metal particles is produced primarily by reduction of Fe(+2) from silicates. One mechanism for the reduction process is the reaction of solar implanted wind protons with the regolith soil during impact events. In this case the presence of hydrogen creates a reducing environment and the thermal pulse from the impact greatly speeds the reaction kinetics. To explore other reducing and thermal environments a series of experiments were done using samples in evacuated capsules buffered by Tantalum and heated to subsolidus temperatures.

Britt, D. T.↗

NASA NTRS1994

Locomotion in a rotating space station: a synthesis of new data with established concepts

Despite technical problems associated with designing a rotating space station it is still thought that such a device may provide a more tolerable work environment and prevent some of the physiological changes that currently pose a threat to long-duration space missions. In the present analysis four case studies are presented and the results show that centrifugal and Coriolis effects could hinder one's ability to walk or run in a natural way in such an environment. In a rotating station that has a nominal 'G-level' equal to that on earth it can be shown that a person running at 3.8 m s -1 could experience foot 'heaviness' effects that range from 1 to 3 g and fore-aft foot 'forces' that range fom -0.5 to +0.5 g. In contrast the hip region could sense a relatively constant 'force' equal to 2 g. With regard to the body as a whole there would be 'weight changes' that depended on the direction of gait. While these conditions imply that locomotion in a rotating space station would be different from normal gait, it is likely that given sufficient training, astronauts could learn optimal strategies to account for centrifugal and Coriolis effects on individual body segments. The learning process would also entail developing strategies on which route to take when moving from one location to another, since in many cases the shortest route would not be the least energy consuming. Such training would be justified if it were shown that artificial gravity was an effective countermeasure to the problems of muscle atrophy and bone loss.

NASA Discipline Musculoskeletal↗

NASA NTRS1974

Indium antimonide crystal growth experiment M562

It was established that ideal diffusion controlled steady state conditions, never accomplished on earth, were achieved during the growth of Te-doped InSb crystals in Skylab. Surface tension effects led to nonwetting conditions under which free surface solidification took place in confined geometry. It was further found that, under forced contact conditions, surface tension effects led to the formation of surface ridges (not previously observed on earth) which isolated the growth system from its container. In addition, it was possible, for the first time, to identify unambiguously: the origin of segregation discontinuities associated with facet growth, the mode of nucleation and propagation of rotational twin boundaries, and the specific effect of mechanical-shock perturbations on segregation. The results obtained prove the advantageous conditions provided by outer space. Thus, fundamental data on solidification thought to be unattainable because of gravity-induced interference on earth are now within reach.

Gatos, H. C.↗

NASA NTRS1978

Flight experience with advanced controls and displays during piloted curved decelerating approaches in a powered-lift STOL aircraft

The control, display, and procedural features are described for a flight experiment conducted to assess the feasibility of piloted STOL approaches along predefined, steep, curved, and decelerating approach profiles. It was found to be particularly important to assist the pilot through use of the flight director computing capability with the lower frequency control-related tasks, such as those associated with monitoring and adjusting configuration trim as influenced by atmospheric effects, and preventing the system from exceeding powerplant and SAS authority limitations. Many of the technical and pilot related issues identified in the course of this flight investigation are representative of similarly demanding operational tasks that are thought to be possible only through the use of sophisticated control and display systems.

Hindson, W. S.↗

NASA NTRS2014

Phase Equilibrium Experiments on Potential Lunar Core Compositions: Extension of Current Knowledge to Multi-Component (Fe-Ni-Si-S-C) Systems

Numerous geophysical and geochemical studies have suggested the existence of a small metallic lunar core, but the composition of that core is not known. Knowledge of the composition can have a large impact on the thermal evolution of the core, its possible early dynamo creation, and its overall size and fraction of solid and liquid. Thermal models predict that the current temperature at the core-mantle boundary of the Moon is near 1650 K. Re-evaluation of Apollo seismic data has highlighted the need for new data in a broader range of bulk core compositions in the PT range of the lunar core. Geochemical measurements have suggested a more volatile-rich Moon than previously thought. And GRAIL mission data may allow much better constraints on the physical nature of the lunar core. All of these factors have led us to determine new phase equilibria experimental studies in the Fe-Ni-S-C-Si system in the relevant PT range of the lunar core that will help constrain the composition of Moon's core.

Righter, K.↗

NASA NTRS1971

Theory of the unmagnetized plasma.

The Vlasov mathematical model of a plasma, which has come to be thought more useful than any other in describing the dynamical behavior of the majority of plasmas of interest, is first examined. Macroscopic variables and moment equations; linear electrostatics solutions; plasma oscillations, ion acoustic waves, and linear instabilities are treated, as well as external fields, 'test' charges, and nonlinear Vlasov phenomena. Plasmas are statistically described, and attention is given to the kinetic theory of the stable, uniform plasma and the Balescu-Lenard equation; two-time ensemble averages and fluctuation spectra in stable plasmas; the kinetic theory of the unstable plasma; and ensembles of Vlasov plasmas. Some illustrative experiments are described. Four appendixes deal with the electrostatic approximation and transverse waves; solution of the linearized Vlasov equation in a magnetic field; estimates of correlation functions from thermal equilibrium; and equivalence of spatially uniform BBGKY and Klimontovich correlations.

Montgomery, D. C.↗

NASA NTRS2007

Aircraft Weather Mitigation for the Next Generation Air Transportation System

Atmospheric effects on aviation are described by Mahapatra (1999) as including (1) atmospheric phenomena involving air motion - wind shear and turbulence; (2) hydrometeorological phenomena - rain, snow and hail; (3) aircraft icing; (4) low visibility; and (5) atmospheric electrical phenomena. Aircraft Weather Mitigation includes aircraft systems (e.g. airframe, propulsion, avionics, controls) that can be enacted (by a pilot, automation or hybrid systems) to suppress and/or prepare for the effects of encountered or unavoidable weather or to facilitate a crew operational decision-making process relative to weather. Aircraft weather mitigation can be thought of as a continuum (Figure 1) with the need to avoid all adverse weather at one extreme and the ability to safely operate in all weather conditions at the other extreme. Realistic aircraft capabilities fall somewhere between these two extremes. The capabilities of small general aviation aircraft would be expected to fall closer to the "Avoid All Adverse Weather" point, and the capabilities of large commercial jet transports would fall closer to the "Operate in All Weather Conditions" point. The ability to safely operate in adverse weather conditions is dependent upon the pilot s capabilities (training, total experience and recent experience), the airspace in which the operation is taking place (terrain, navigational aids, traffic separation), the capabilities of the airport (approach guidance, runway and taxiway lighting, availability of air traffic control), as well as the capabilities of the airplane. The level of mitigation may vary depending upon the type of adverse weather. For example, a small general aviation airplane may be equipped to operate "in the clouds" without outside visual references, but not be equipped to prevent airframe ice that could be accreted in those clouds.

Stough, H. Paul, III↗

NASA NTRS2005

Simulation of the Genesis of Hurricane Javier (2004) in the Eastern Pacific

NASA is preparing for the Tropical Cloud Systems and Processes (TCSP) field experiment in July 2005, a joint effort with NOAA to study tropical cloud systems and tropical cyclone genesis in the Eastern Pacific. A major thrust of the TCSP program is the improvement of the understanding and prediction of tropical cyclone genesis, intensity, motion, rainfall potential, and landfall impacts using remote sensing and in-situ data, as well as numerical modeling, particularly as they relate to the three phases of water. The Eastern Pacific has the highest frequency of genesis events per unit area of any region worldwide. African easterly waves, mesoscale convective systems (MCSs), and orographic effects are thought to play roles in the genesis of tropical cyclones there. The general consensus is that tropical depressions form in association with one or more mid-level, mesoscale cyclonic vortices that are generated within the stratiform region of the MCS precursors. To create the warm core tropical depression vortex, however, the midlevel cyclonic circulation must somehow extend down to the surface and the tangential winds must attain sufficient strength (-10 m s- ) to enable the wind-induced surface heat exchange to increase the potential energy of the boundary layer air.

Braun, Scott↗

NASA NTRSDate not supplied

Metal-silicate Partitioning of Re, Ru, Pt, Os, Ti, Nb, and Ta in Reduced Differentiated Planetary Bodies

Siderophile (iron-loving) elements are strongly fractionated during differentiation of planetary bodies into core and mantle [1]. Because the fractionation is controlled by the pressure, temperature, redox conditions, and composition, this group of elements can provide important constraints on the conditions of accretion and core formation in early solar system bodies (planetesimals) and planets (Earth, Mercury, Venus)[2]. At the reducing conditions thought to prevail in the early solar system, Si is known to alloy with FeNi metallic liquids (e.g., [3]) affecting the activity coefficients of siderophile elements in FeNi liquids and thus ultimately their detailed partitioning between metal and silicate melt. The effect of Si can be significant for some siderophile elements, as demonstrated previously by (e.g., [4]: Ni, Co; [5,6]: Ge, As, Sb, Pd, Pt, Au). The effect of Si has not yet been determined for several key groups of siderophile elements including the highly siderophile Re, Ru and Os, and the weakly siderophile Ta, Nb, and Ti. Here, we report new experiments designed to quantify the effect of Si on the partitioning of Re, Pt, Os, Ru, Ti, Ta and Nb between metal and silicate melts. The results will be used to evaluate metal/silicate equilibrium for Nb, Ta, Ti and Nb/Ta ratios in planetary mantles, mantle concentrations of Ru, Re, Pt, Os during accretion, the evolution of Re/Os, Pt/Os ratios in magma oceans, and the role of late veneer in establishing Re and Ru abundances in the terrestrial mantle.

core formation↗

NASA NTRS2016

Insights Into the Aqueous History of Mars from Acid-Sulfate Weathered Phyllosilicates

Phyllosilicates on Mars are thought to have formed during Mars' earliest Noachian geologic era (approx. 4.1-3.7 Ga). Sulfate formation, on the other hand, requires more acidic conditions which are thought to have occurred later during Mars' Hesperian era (approx. 3.7-3.0 Ga). Therefore, regions on Mars where phyllosilicates and sulfates are found in close proximity to each other provide evidence for the aqueous conditions during this global transition. Both phyllosilicates and sulfates form in the presence of water and thus give clues to the aqueous history of Mars and its potential for habitability. Phyllosilicates that formed during the Noachian era would have been weathered by the prevailing acidic conditions that define the Hesperian. Therefore, the purpose of this study is to characterize the alteration products of acid-sulfate weathered phyllosilicates in laboratory experiments, focusing on the Fe/Mg-smectites commonly identified on Mars. We also compare our results to observations of phyllosilicates and sulfates on Mars in regions such as Endeavour Crater and Mawrth Vallis to understand the formation process of sulfates and constrain the aqueous history of these regions.

Craig, P. I.↗

NASA NTRS1983

Photographs of lightning from the Space Shuttle

The equipment used in the Nighttime Daytime Optical Survey of Lightning experiment, carried out on the second and fourth Space Shuttle missions, is described. Attention is then given to one of the more spectacular lightning photographs, that of a Y-shaped discharge taken by Thomas K. Mattingly II on the night of June 29, 1982, over southern Brazil. Since the orientation of the camera with respect to the earth is not known, the scale of the photograph cannot be determined accurately. If the camera had been looking directly down from the vehicle at its altitude of 300 km, the Y-shaped pattern would be approximately 60 km long and 40 km wide. If, as is thought probable, the camera was not looking directly down, the pattern would have somewhat greater dimensions. The photographs show that illumination from lightning discharges can cover a rather wide area.

Vonnegut, B.↗

NASA NTRS2015

Sulfate Mineral Formation from Acid-Weathered Phyllosilicates: Implications for the Aqueous History of Mars

Phyllosilicates on Mars are thought to have formed under neutral to alkaline conditions during Mars' earliest Noachian geologic era (approx. 4.1-3.7 Gya). Sulfate formation, on the other hand, requires more acidic conditions which are thought to have occurred later during Mars' Hesperian era (approx. 3.7-3.0 Gya). Therefore, regions on Mars where phyllosilicates and sulfates are found in close proximity to each other provide evidence for the geologic and aqueous conditions during this global transition. Both phyllosilicates and sulfates form in the presence of water and thus give clues to the aqueous history of Mars and its potential for habitability. Phyllosilicates that formed during the Noachian era may have been weathered by the prevailing acidic conditions that characterize the Hesperian. Therefore, the purpose of this study is to characterize the alteration products resulting from acid-sulfate weathered phyllosilicates in laboratory experiments. This study focuses on two phyllosilicates commonly identified with sulfates on Mars: nontronite and saponite. We also compare our results to observations of phyllosilicates and sulfates on Mars to better understand the formation process of sulfates in close proximity to phyllosilicates on Mars and constrain the aqueous conditions of these regions on Mars.

Craig, P. I.↗

NASA NTRS1999

Behavior of Windblown Sand on Mars: Results from Single-Particle Experiments

Experiments are investigating the behavior of individual sand grains in the high-energy martian aeolian regime. Energy partitioning during impact of a saltating grain determines grain longevity, but it also influences the way in which the bed becomes mobilized by reptation. When single grains of sand are fired into loose beds, the bed can absorb up to 90% of the impact energy by momentum transfer to other grains; it has been discovered that the impacting grains cause circular craters even at low impact angles. Hundreds of grains can be splashed by a single high-velocity (100 m/s) impact causing more bed disturbance through reptation than previously thought. The research is supported by NASA's PG&G Program. Because the martian aeolian environment in both high energy and of long duration, the most mobile fractions of windblown sand should have eradicated themselves by attrition, unless sand supply has kept pace with destruction. It is therefore important to understand the rate of grain attrition in order to make sense of the existence of vast dune fields on Mars. Attrition, has been addressed in other studies, but precise data for a single saltating grain striking a loose bed of sand have not been acquired -- the quintessential case to be understood for dunes on Mars. To acquire these data, we are employing a compound crossbow which has the bolt-firing mechanism replaced with a pneumatically-automated sabot system. The sabot can launch individual grains of sand of any size between several millimeters and about 50 microns, at velocities up to 100m/s. This is around the maximum velocity expected for saltating grains on Mars. The sabot sled is equipped with photoelectric sensors for measuring shot velocity. Baffling of the grain's exit orifice has enabled projection of single grains without significant aerodynamic effects from the sabot. Grains are fired into loose beds of sand at about 15 degrees from the horizontal (typical saltation trajectory at impact) while being filmed on high-speed video. High-intensity pulse illumination for the grains is triggered by the solenoid-operated bow trigger. A 45 degree mirror over the impact site provides simultaneous horizontal and vertical images of the impact on each video frame. UV fluorescence is enabling grain and grain-fragment recovery. At 100 m/s, grains of all sizes shatter into many fragments when the sand is replaced with a solid target. Kinetic energy of the grains at this velocity exceeds the critical energy for catastrophic failure of minerals. Although probably exceptional as a grain speed, it suggests that conditions on Mars might elevate materials into an attrition regime not encountered on other planets; individual grains blown across rock pavements on Mars will have short lifespans. When experimental grains impact loose (dune) sand, much, if not most of the kinetic energy is converted into momentum of other grains. Using high-speed filming, the energy involved in splashing grains at the impact site can be derived from the size of the crater, the speed of the splashed grains, and the rebound speed of the impactor. The amount of energy partitioned into material failure (as opposed to momentum) is too small a fraction of the total to be calculated under these circumstances. This does not necessarily mean that little damage occurs to the grains (the full extent of the damage has yet to be determined) because only a small fraction of the impact energy is required for inducing brittle fracture. Damage is orders of magnitude less than during impact against solid surfaces.

Marshall, J. R.↗