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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Influence of anthropogenic CCN on stratus microphysics

Analysis of the airborne measurements of CCN from the FIRE marine stratocumulus project of 1987 shows that continental aerosol was pervasive in air immediately above widespread stratus decks more than 500 km from the coast of California. Indications are that a large portion of the CCN component of the continental aerosol is anthropogenic. An important issue concerning continental CCN production is the question of the ratio of manmade CCN to natural particle production processes. The measurements certainly indicate that southern California air pollution or at the least continental aerosol is manifested in the cloud and above cloud aerosol.

Hudson, James G.↗
NASA NTRS1992

Consortium for materials development in space interaction with Space Station Freedom

The Consortium for Materials Development in Space (CMDS) is one of seventeen Centers for the Commercial Development of Space (CCDS) sponsored by the Office of Commercial Programs of NASA. The CMDS formed at the University of Alabama in Huntsville in the fall of 1985. The Consortium activities therefore will have progressed for over a decade by the time Space Station Freedom (SSF) begins operation. The topic to be addressed here is: what are the natural, mutually productive relationships between the CMDS and SSF? For management and planning purposes, the Consortium organizes its activities into a number of individual projects. Normally, each project has a team of personnel from industry, university, and often government organizations. This is true for both product-oriented materials projects and for infrastructure projects. For various projects Space Station offers specific mutually productive relationships. First, SSF can provide a site for commercial operations that have evolved as a natural stage in the life cycle of individual projects. Efficiency and associated cost control lead to another important option. With SSF in place, there is the possibility to leave major parts of processing equipment in SSF, and only bring materials to SSF to be processed and return to earth the treated materials. This saves the transportation costs of repeatedly carrying heavy equipment to orbit and back to the ground. Another generic feature of commercial viability can be the general need to accomplish large through-put or large scale operations. The size of SSF lends itself to such needs. Also in addition to processing equipment, some of the other infrastructure capabilities developed in CCDS projects may be applied on SSF to support product activities. The larger SSF program may derive mutual benefits from these infrastructure abilities.

Lundquist, Charles A.↗
NASA NTRS1974

Production of edible carbohydrates from formaldehyde in a spacecraft. pH variations in the calcium hydroxide catalyzed formose reaction

The study of the calcium hydroxide catalyzed condensation of formaldehyde was extended to a batch reactor system. Decreases in pH were observed, often in the acid regime, when using this basic catalyst. This observation was shown to be similar to results obtained by others using less basic catalysts in the batch mode. The relative rates of these reactions are different in a batch reactor than in a continuous stirred tank reactor. This difference in relative rates is due to the fact that at any degree of advancement in the batch system, the products have a history of previous products, pH, and dissolved catalyst. The relative rate differences can be expected to yield a different nature of product sugars for the two types of reactors.

Weiss, A. H.↗
NASA NTRS1986

The exposure history of Jilin and production rates of cosmogenic nuclides

Jilin, the largest known story meteorite, is a very suitable object for studying the systematics of cosmic ray produced nuclides in stony meteorites. Its well established two stage exposure history even permits to gain information about two different irradiation geometries (2pi and 4pi). All stable and long-lived cosmogenic nuclides measured in Jilin so far correlate well with each other. An example is shown where the Al-26 activities are plotted vs. the spallogenic Ne-21 concentration. These records of cosmic-ray interaction in Jilin can be used both to determine the history of the target and to study the nature of production rate profiles. This is unavoidably a bootstrap process, involving studying one with assumption about the other. Production rate equations are presented and discussed.

Heusser, G.↗
NASA NTRS2019

Soil Moisture Data Assimilation

Accurate knowledge of soil moisture at the continental scale is important for improving predictions of weather, agricultural productivity and natural hazards, but observations of soil moisture at such scales are limited to indirect measurements, either obtained through satellite remote sensing or from meteorological networks. Land surface models simulate soil moisture processes, using observation-based meteorological forcing data, and auxiliary information about soil, terrain and vegetation characteristics. Enhanced estimates of soil moisture and other land surface variables, along with their uncertainty, can be obtained by assimilating observations of soil moisture into land surface models. These assimilation results are of direct relevance for the initialization of hydro-meteorological ensemble forecasting systems. The success of the assimilation depends on the choice of the assimilation technique, the nature of the model and the assimilated observations, and, most importantly, the characterization of model and observation error. Systematic differences between satellite-based microwave observations or satellite-retrieved soil moisture and their simulated counterparts require special attention. Other challenges include inferring root-zone soil moisture information from observations that pertain to a shallow surface soil layer, propagating information to unobserved areas and downscaling of coarse information to finer-scale soil moisture estimates. This chapter summarizes state-of-the-art solutions to these issues with conceptual data assimilation examples, using techniques ranging from simplified optimal interpolation to spatial ensemble Kalman filtering. In addition, operational soil moisture assimilation systems are discussed that support numerical weather prediction at ECMWF and provide value-added soil moisture products for the NASA Soil Moisture Active Passive mission.

radar backscatter↗
NASA NTRS2011

Thoughts Without Content are Empty, Intuitions Without Concepts are Blind - Determinism and Contingency Revisited

Was the emergence of life a predictable outcome of chemical evolution on earth? Could evolution produce life very different from ours? These are one of the oldest questions in the field of the origin of life that not only have broad philosophical implications but also impact how we approach the problem from the methodological standpoint. Framing the issue in terms of the dichotomy between contingency and determinism is not a fortunate because these two terms in their conventional meaning are neither mutually exclusive nor jointly exhaustive. Determinism, represented in natural sciences by Newtonian physics, relies on the assumption that every event is causally determined by a chain of previous events. In the context of the origin of life it means that once the initial conditions on the early earth have been specified further evolution follows inevitably. Considering uncertainties about conditions on the prebiotic earth, many plausible sets of initial conditions can be defined, each followed by a separate deterministic trajectory. This conventional understanding of determinism does not admit contingency. Further, it has no implications for evaluating how many sets of initial conditions lead to the emergence of life. It appears that a better framing of the problem is as follows: given plausible sets of initial conditions on the early earth how probable and broadly spread are evolutionary trajectories that lead to life? Instead of undertaking an impossible task of specifying microscopic initial conditions for all components of the system one uses a reduced representation of this system and specify only a small set of essential macroscopic parameters, values (or ranges of values) of which can be identified, inferred or estimated from experiment, theory or historical record. The following evolutionary trajectories are still governed by laws of physics and chemistry but become probabilistic and "contingency" is admitted as variations in other variables in the system. A similar reasoning is common in other fields of science, for example in statistical mechanics. Some trajectories lead to life, perhaps in different forms, whereas others do not. Of our true interest is the ratio of these two outcomes. The issue of determinism does not directly enter the picture. The debate about the likelihood of the emergence of life is quite old. One view holds that the origin of life is an event governed by chance, and the result of so many random events (contingencies) is unpredictable. This view was eloquently expressed by Monod. In his book "Chance or Necessity" he argued that life was a product of "nature's roulette." In an alternative view, expressed in particular by deDuve and Morowitz, the origin of life is considered a highly probable or even inevitable event (although its details need not be determined in every respect). Only in this sense the origin of life can be considered a "deterministic event".

Pohorille, Andrew↗
NASA NTRS1974

Spectroscopy and reactions of molecules important in chemical evolution

The research includes: (1) hot hydrogen atom reactions in terms of the nature of products produced, mechanism of the reactions and the implication and application of such reactions for molecules existing in interstellar clouds, in planetary atmospheres, and in chemical evolution; (2) photochemical reactions that can lead to molecules important in chemical evolution, interstellar clouds and as constituents in planetary atmospheres; and (3) spectroscopic and theoretical properties of biomolecules and their precursors and where possible, use these to understand their photochemical behavior.

Becker, R. S.↗
NASA NTRS1974

Biological modulation of the earth's atmosphere

Review of the evidence that the earth's atmosphere is regulated by life on the surface so that the probability of growth of the entire biosphere is maximized. Acidity, gas composition including oxygen level, and ambient temperature are enormously important determinants for the distribution of life. The earth's atmosphere deviates greatly from that of the other terrestrial planets in particular with respect to acidity, composition, redox potential and temperature history as predicted from solar luminosity. These deviations from predicted steady state conditions have apparently persisted over millions of years. These anomalies may be evidence for a complex planet-wide homeostasis that is the product of natural selection. Possible homeostatic mechanisms that may be further investigated by both theoretical and experimental methods are suggested.

Margulis, L.↗
NASA NTRS1976

Energy requirements of a biosphere

The question is considered of whether a biosphere similar to that on earth could exist in the region of the outer planets, where relatively little light is available for photosynthetic processes. The type of photosynthesis most abundant on earth is discussed along with light conversion in photosynthesis, the light-harvesting system in plants, photosynthetic efficiency, and carbon production in nature. The dynamic range of metabolic rates is examined, and photosynthesis in anaerobic organisms is described. It is suggested that organisms having very large photosynthetic pigment units would thrive in the light intensities prevailing on Titan and that the surface of Titan might well be able to maintain a biosphere driven by oxygen-generating photosynthesis.

Kok, B.↗
NASA NTRS1978

Methane-producing bacteria - Natural fractionations of the stable carbon isotopes

Procedures for determining the C-13/C-12 fractionation factors for methane-producing bacteria are described, and the fractionation factors (CO2/CH4) for the reduction of CO2 to CH4 by pure cultures are 1.045 for Methanosarcina barkeri at 40 C, 1.061 for Methanobacterium strain M.o.H. at 40 C, and 1.025 for Methanobacterium thermoautotrophicum at 65 C. The data are consistent with the field determinations if fractionation by acetate dissimilation approximates fractionations observed in natural environments. In other words, the acetic acid used by acetate dissimilating bacteria, if they play an important role in natural methane production, must have an intramolecular isotopic fractionation (CO2H/CH3) approximating the observed CO2/CH4 fractionation.

Games, L. M.↗
NASA NTRS1979

Laboratory simulations of the Viking Labeled Release experiment - Kinetics following second nutrient injection and the nature of the gaseous end product

Injection of (C-14)-labeled nutrient onto Mars soil produced an evolution of C-14 gas in the Viking Labeled Release (LR) experiment. However, a second injection of nutrient seven days later was followed by an abrupt diminution of the amount of radioactive gas in the test cell. Simulation experiments performed in the LR Test Standards Module (TSM) have yielded a plausible explanation for this diminution. Radioactive carbon gases were injected into the TSM test cell in the presence and absence of two Mars analog soils. After equilibration, water was injected and its effect observed. The results indicate that the flight data following second nutrient injection can be explained on a physico-chemical basis involving a carbon dioxide/water/soil equilibrium in the test cell. The results also suggest that the gaseous end product of the Labeled Release reaction on Mars is more likely carbon dioxide than carbon monoxide.

Levin, G. V.↗
NASA NTRS1984

Helium concentration in the earth's lower atmosphere

A helium content of 5.222 + or - 0.017 ppm by volume has been established by measurements during 1981 of the earth's lower atmosphere, using isotope dilution mass spectrometry. This compares well with the currently accepted value of 5.239 + or - 0.004 ppm determined by Gluekhauf (1946) on the basis of measurements conducted in the 1930s. While processes that could have altered helium concentrations since the 1930s imply a significant increase in concentration, due to helium release during natural gas production, possible net helium losses from the atmosphere are not easily quantifiable.

Oliver, B. M.↗
NASA NTRS1985

Increased productivity in flight with voice commanding

Automatic Speech Recognition technology has matured to the point where it can provide a viable means of increasing productivity by naturalizing the man-machine interface. With ever increasing workloads being placed on astronauts, speech recognition may provide an alternative means of system controlling that would reduce the task burden. Voice commanding, allowing hands-free operation, can be especially effective during operations requiring simultaneous system control. A flight experiment is under development to demonstrate the operational effectiveness of voice control by commanding the Space Shuttle's Closed Circuit Television (CCIV) system. This experiment will help direct future applications of voice entry to space operations.

Jordan, W. T.↗
NASA NTRS1989

Observations of, and sources of the spatial and temporal variability of ozone in the middle atmosphere on climatological time scales (OZMAP) and equatorial dynamics: Seasonal variations of ozone trends

The long term trends (least square linear regression with time) of ozone content at seven European, seven North American, three Japanese and two tropical stations during 21 years (1964 to 1984) are analyzed. In all regions negative trends are observed during the 1970s, but are partly compensated by limited periods of positive trends during the late 1960s and late 1970s. Solely the North American ozone data show negative trends in all 10 year periods. When the long term ozone trends are evaluated for each month of the year separately, a seasonal variation is revealed, which in Europe and North America has largest negative trends in late winter and spring. While in Europe the negative trends in winter/spring are partly compensated by positive trends in summer, in North America the summer values reach only zero, retaining the significant negative trend in annual mean values. In contrast to the antarctic ozone hole, the spring reduction of ozone in Europe and in North America is associated with stratospheric temperatures increasing in the analyzed period and therefore is consistent with the major natural ozone production and loss processes.

Entzian, G.↗
NASA NTRS1991

Space engineering

Human productivity was studied for extravehicular tasks performed in microgravity, particularly including in-space assembly of truss structures and other large objects. Human factors research probed the anthropometric constraints imposed on microgravity task performance and the associated workstation design requirements. Anthropometric experiments included reach envelope tests conducted using the 3-D Acoustic Positioning System (3DAPS), which permitted measuring the range of reach possible for persons using foot restraints in neutral buoyancy, both with and without space suits. Much neutral buoyancy research was conducted using the support of water to simulate the weightlessness environment of space. It became clear over time that the anticipated EVA requirement associated with the Space Station and with in-space construction of interplanetary probes would heavily burden astronauts, and remotely operated robots (teleoperators) were increasingly considered to absorb the workload. Experience in human EVA productivity led naturally to teleoperation research into the remote performance of tasks through human controlled robots.

Alexander, Harold L.↗
NASA NTRS1989

A Mars base

This study was initiated to provide an approach to the development of a permanently manned Mars base. The objectives for a permanently manned Mars base are numerous. Primarily, human presence on Mars will allow utilization of new resources for the improvement of the quality of life on Earth, allowing for new discoveries in technologies, the solar system, and human physiology. Such a mission would also encourage interaction between different countries, increasing international cooperation and leading to a stronger unification of mankind. Surface studies of Mars, scientific experiments in the multiple fields, the research for new minerals, and natural resource production are more immediate goals of the Mars mission. Finally, in the future, colonization of Mars will ensure man's perpetual presence in the universe. Specific objectives of this study were: (1) to design a Mars habitat that minimizes the mass delivered to the Mars surface, provides long-stay capability for the base crew, and accommodates future expansion and modification; (2) to develop a scenario of the construction of a permanently manned Mars base; and (3) to incorporate new and envisioned technologies.

Soule, Veronique↗