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NASA NTRS2017

Lightning NOx Estimates from Space-Based Lightning Imagers

The intense heating of air by a lightning channel, and subsequent rapid cooling, leads to the production of lightning nitrogen oxides (NOx = NO + NO2) as discussed in Chameides [1979]. In turn, the lightning nitrogen oxides (or "LNOx" for brevity) indirectly influences the Earth's climate because the LNOx molecules are important in controlling the concentration of ozone (O3) and hydroxyl radicals (OH) in the atmosphere. Climate is most sensitive to O3 in the upper troposphere, and LNOx is the most important source of NOx in the upper troposphere at tropical and subtropical latitudes; hence, lightning is a useful parameter to monitor for climate assessments. The National Climate Assessment (NCA) program was created in response to the Congressionally-mandated Global Change Research Act (GCRA) of 1990. Thirteen US government organizations participate in the NCA program which examines the effects of global change on the natural environment, human health and welfare, energy production and use, land and water resources, human social systems, transportation, agriculture, and biological diversity. The NCA focuses on natural and human-induced trends in global change, and projects major trends 25 to 100 years out. In support of the NCA, the NASA Marshall Space Flight Center (MSFC) continues to assess lightning-climate inter-relationships. This activity applies a variety of NASA assets to monitor in detail the changes in both the characteristics of ground- and space- based lightning observations as they pertain to changes in climate. In particular, changes in lightning characteristics over the conterminous US (CONUS) continue to be examined by this author using data from the Tropical Rainfall Measuring Mission Lightning Imaging Sensor. In this study, preliminary estimates of LNOx trends derived from TRMM/LIS lightning optical energy observations in the 17 yr period 1998-2014 are provided. This represents an important first step in testing the ability to make remote retrievals of LNOx from a satellite-based lightning sensor. As is shown, the methodology can also be directly applied to more recently launched lightning mappers, such as the Geostationary Lightning Mapper, and the International Space Station LIS.

Koshak, William J.↗

NASA NTRS2018

A Dual Multilayer Insulation Blanket Concept to Radically Reduce Heat Loss From Thermally Controlled Spacecraft and Instruments

At large distances from the Sun (e.g. Jupiter/Saturn), the solar flux is less than 4% that at Earth. This requires very large solar arrays to meet the power demands of a typical new mission concept. Heat loss through Multi-Layer Insulation (MLI) blankets typically constitutes the vast majority of the total heat loss. Hence, improvements to MLI blankets that reduce heat loss are advantageous to the spacecraft design. The overall effective emittance (ε*) of MLI is usually a range dependent on the number of layers, size of blanket, seams, feedthroughs, layer density and operating temperatures of the heat source and heat sink. A concept has been developed at JPL to reduce the ε* by as much as a factor of two, which produces a corresponding reduction in heat losses. This concept utilizes two MLI blankets physically separated by traditional bumpers or spacers used for micrometeoroid protection. The outer surface of the inner blanket and the inner surface of the outer blanket are low emissivity surfaces to further minimize the total ε* of the overall dual MLI system. Analytical predictions of a dual MLI concept have been made using test data based ε* correlations. A development test has been conducted to validate the dual blanket design’s performance. This paper will describe the dual blanket design concept, schemes for its implementation, and the corresponding test results to validate its performance.

Duran, Mark↗

NASA NTRS1986

Measurements of the dynamics of the high-latitude thermosphere

The study of the dynamics and thermodynamics of the earth's upper atmosphere has made significant progress over the past few years owing to the availability of new global-scale data sets from the Dynamics Explorer satellites. The thermospheric wind and temperature fields at high altitude have been observed to depend strongly on forcing processes of magnetospheric origin. A key momentum source is due to the drag effect of ions convecting in response to electric fields mapped down on the ionosphere from magnetospheric boundary regions. Likewise, an important heat source derives from Joule or frictional dissipation due to ion/neutral difference velocities governed by magnetospheric forcing. In this paper the progress made over the last 2-3 years initiated by the new satellite measurements is discussed, and published data on ion and neutral motions are reviewed in the context of the energy and momentum coupling between the magnetosphere and the ionosphere/neutral upper atmosphere.

Killeen, T. L.↗

NASA NTRS1991

Consequences of wave-particle interactions on chaotic acceleration

The recent model of Ashour-Abdalla et al. (1991) has proposed that the earth's plasma sheet can be formed by chaotic acceleration in a magnetotail-like field configuration. The ion velocity distributions created by chaotic acceleration have unstable features and represent robust free energy sources for kinetic plasma waves that can modify the original distributions. In the plasma sheet boundary layer, field-aligned ion beamlets are formed which drive a host of instabilities creating a broadbanded noise spectrum and cause thermal spreading of the beamlets. In addition, there is strong heating of any cold background plasma that may be present. In the central plasma sheet, ion antiloss cone distributions are created which are unstable to very low frequency waves that saturate by filling the antiloss cone.

Schriver, David↗

NASA NTRS2005

A Viable Scheme for Elemental Extraction and Purification Using In-Situ Planetary Resources

NASA's new strategic direction includes establishing a self-sufficient, affordable and safe human and robotic presence outside the low earth orbit. Some of the items required for a self-sufficient extra-terrestrial habitat will include materials for power generation (e.g. Si for solar cells) and habitat construction (e.g. Al, Fe, and Ti). In this paper we will present a viable elemental extraction and refining process from in-situ regolith which would be optimally continuous, robotically automated, and require a minimum amount of astronaut supervision and containment facilities, The approach is based on using a concentrated heat source and translating sample geometry to enable simultaneous oxide reduction and elemental refining. Preliminary results will be presented to demonstrate that the proposed zone refining process is capable of segregating or refining important elements such as Si (for solar cell fabrication) and Fe (for habitat construction). A conceptual scheme will be presented whereby such a process could be supported by use of solar energy and a precursor robotic mission on the surface of the moon.

Sen, S.↗

NASA NTRS2020

Nonstationary Quasiperpendicular Shock and Ion Reflection at Mars

Collisionless shocks in space plasma are regions of heating and acceleration of charged particles and dissipation of kinetic energy. These accelerated particles are the source of electromagnetic emissions from supernova remnants and other astrophysical structures.At high Mach numbers, shocks can be inherently nonstationary and exhibit modulated energy transfer and recurring plasma compression areas in the form of reformation. We use data from the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft to study reformation of the Martian bow shock which has a relatively high curvature compared to that at Earth and the upstream solar wind is often mass loaded with a population of pickup ions. We show evidence of ion reflection effects in reformation of a supercritical quasi-perpendicular shock.

Hadi Madanian↗

NASA NTRS1987

Refractory semiconductors for high temperature thermoelectric energy conversion

Thermoelectric energy conversion utilizing nuclear heat sources has been employed for several decades to generate power for deep space probes. In the past, lead telluride and, more recently, silicon-germanium alloys have been the prime choices as thermoelectric materials for this application. Currently, a number of refractory semiconductors are under investigation at the Jet Propulsion Laboratory in order to produce power sources of higher conversion efficiency and, thus, lower mass per unit of power output. Included among these materials are improved Si-Ge alloys, rare earth compounds and boron-rich borides. The criteria used to select thermoelectric materials, in general, and the above materials, in particular, will be discussed. The current state of the art and the accomplishments to date in thermoelectric materials research will be reviewed.

Wood, Charles↗

NASA NTRS1988

Highly labile elements

Certain elements of high lability are very responsive to thermal processes, being either highly volatile during primary nebular condensation or highly mobile by postaccretionary metamorphic or shock heating. Data for highly labile elements indicate that different thermal processes were important in the genesis of each of the chondritic groups and a discussion of each is given. Contents of highly labile elements in a given group of contemporary falls differ from those of the same group that fell in Antarctica more than 0.1 Myr ago. This difference is due either to a time-dependent change in meteorite sources or, less likely, orbital variation of the meteorite flux to Earth.

Lipschutz, Michael E.↗

NASA NTRS2011

Introduction to: Atlantic Meridional Overturning Circulation(AMOC)

A striking conclusion of the Intergovernmental Panel on Climate Change 2007 report is the crucial role that the Atlantic Meridional Overturning Circulation (AMOC) may play in anthropogenic climate change. However, these IPCC coupled climate simulations show a broad range of uncertainty in the magnitude and timing of AMOC transport change ranging from none to nearly complete collapse within the 21st century. The potential consequences of large changes in the characteristics of AMOC have motivated the creation in the United States of an interagency program and implementation plan to develop monitoring and prediction capabilities for the AMOC This program parallels the development of substantial monitoring efforts by European, South American and African countries -- notably the UK Rapid and Rapid-Watch programs. The papers contained in this volume are derived from presentations at the First U.S. Atlantic Meridional Overturning Circulation (AMOC) Meeting held 4 - 6 May, 2009 to review the US implementation plan and its coordination with other monitoring activities. The Atlantic Meridional Overturning Circulation consists of multiple components illustrated in an attached figure. Water enters the South Atlantic at upper and intermediate depths through both western and eastern routes (where eddy transport is especially important) and is transported northward across the equator, where it recirculates within the northern subtropical and subpolar gyres. The northern end is defined by the sinking regions of the Nordic Seas and the Labrador Sea where the waters that eventually form the upper and lower branches of North Atlantic Deep Water are conditioned. High surface salinities, the result of high net evaporation in the tropics and subtropics (including the Mediterranean Sea), and presence of regions of the Arctic Ocean that remain ice-free even in winter allow for the rapid cooling and thus densification of surface water. This dense surface water becomes the source of deep water formation in the sinking regions. In addition to transporting mass, the AMOC transports roughly half of the total amount of heat carried northward through the northern subtropics (down the temperature-gradient) by the ocean. In contrast in the Southern Hemisphere AMOC transports heat up-gradient from the cool Circumpolar Current to the warm tropics. Paleoevidence suggests that AMOC heat transport in the two hemispheres has varied over time in ways intimately tied to millennial changes in the Earth's climate. In one example, the abrupt Younger Dryas spell of cold weather over the North Atlantic, which began 13,000 years ago, has generally been linked to a millennial shutdown of the AMOC as a result of massive freshwater discharge from the North American continent. The current AMOC monitoring array consists of a series of instrumented transects located across key passages (see Cunningham et al., 2010 for a recent review). In the Arctic and sub-Arctic, transects cross Fram Strait, Denmark Strait and the Faroe Channel (connecting Greenland, Iceland, and the United Kingdom), as well as the entrance to the Labrador Sea. Further south and extending outwards from the east coast of North America there are a series of monitoring arrays including arrays of the Canadian Atlantic Zone Monitoring Program, deployments of the Rapid Western Atlantic Variability Experiment (WAVE), Line W at 39 N, as well as the Rapid-MOC moored array. The latter spans the entire Atlantic basin along 26.5 N. At tropical latitudes we have the Meridional Overturning Variability Experiment (MOVE) array at 16 N, while in the Southern Hemisphere a corresponding basin-spanning transect is being established at the latitude of Cape of Good Hope, complemented by arrays at Drake Passage.

Hakkinen, Sirpa↗

NASA NTRS2015

Lightweight Damage Tolerant, High-Temperature Radiators for Nuclear Power and Propulsion

NASA is increasingly emphasizing exploration to bodies beyond near-Earth orbit. New propulsion systems and new spacecraft are being built for these missions. As the target bodies get further out from Earth, high energy density systems, e.g., nuclear fusion, for propulsion and power will be advantageous. The mass and size of these systems, including supporting systems such as the heat exchange system, including thermal radiators, will need to be as small as possible. Conventional heat exchange systems are a significant portion of the total thermal management mass and size. Nuclear electric propulsion (NEP) is a promising option for high-speed, in-space travel due to the high energy density of nuclear fission power sources and efficient electric thrusters. Heat from the reactor is converted to power for use in propulsion or for system power. The heat not used in the power conversion is then radiated to space as shown in figure 1. Advanced power conversion technologies will require high operating temperatures and would benefit from lightweight radiator materials. Radiator performance dictates power output for nuclear electric propulsion systems. Pitch-based carbon fiber materials have the potential to offer significant improvements in operating temperature, thermal conductivity, and mass. These properties combine to allow significant decreases in the total mass of the radiators and significant increases in the operating temperature of the fins. A Center-funded project at NASA Marshall Space Flight Center has shown that high thermal conductivity, woven carbon fiber fins with no matrix material, can be used to dissipate waste heat from NEP systems and because of high specific power (kW/kg), will require less mass and possibly less total area than standard metal and composite radiator fins for radiating the same amount of heat. This project uses an innovative approach to reduce the mass and size required for the thermal radiators to the point that in-space NEP and power is enabled. High thermal conductivity carbon fibers are lightweight, damage tolerant, and can be heated to high temperature. Areal densities in the NASA set target range of 2 to 4 kg/m2 (for enabling NEP) are achieved and with specific powers (kW/kg) a factor of about 7 greater than conventional metal fins and about 1.5 greater than carbon composite fins. Figure 2 shows one fin under test. All tests were done under vacuum conditions.

Craven, Paul D.↗

NASA NTRSDate not supplied

Variation and evolution of atmospheric structure over the SEA BB season as seen from aircraft and reanalysis

The presence of absorbing aerosols and atmospheric water vapor will impact clouds both radiatively and dynamically. The atmosphere over the southeast Atlantic Ocean (SEA) experiences consistent springtime biomass burning (BB) smoke from widespread agricultural fires on the African continent. This smoke layer is initially lofted high in a continental mixed layer (~5-6km) and is then transported westward into the free troposphere where it overlies and ultimately mixes into the underlying stratocumulus-topped oceanic boundary layer. Coincident with this smoke is an elevated humidity signal which is present from the time a given airmass is over the continental source region. ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) was a NASA Earth Venture Suborbital mission with the goal of measuring aerosol, cloud, and atmospheric properties over this region over three deployments in September 2016, August 2017, and October 2018. Measurements included in situ profile measurements of aerosol physical and optical properties, trace gas concentrations, and cloud properties, as well as column measurements of aerosol optical depth and trace gas concentrations from an airborne sun photometer, allowing for calculation of radiative heating at different altitudes. Here we present results from the three ORACLES deployments over the southeast Atlantic Ocean. The airborne observations capture both seasonal patterns (August through October) and spatial patterns (north/south and east/west) in the vertical smoke distribution and its correlation to atmospheric specific humidity over the SEA basin. We describe the observed variations and show that the variability in both meteorological and emissions is largely captured in the European Centre for Medium-range Weather Forecasting Copernicus Atmosphere Monitoring Service (ECMWF CAMS) reanalysis, which allows for a more systematic examination of the relative frequency of observed conditions and their radiative impact over the region. Finally, we discuss the broader radiative and dynamical implications of these results for conditions of biomass burning aerosols overlying stratocumulus clouds.

Kristina Marie Myers Pistone↗

NASA NTRS1994

Axial focusing of impact energy in the Earth's interior: Proof-of-principle tests of a new hypothesis

A causal link between major impact events and global processes would probably require a significant change in the thermal state of the Earth's interior, presumably brought about by coupling of impact energy. One possible mechanism for such energy coupling from the surface to the deep interior would be through focusing due to axial symmetry. Antipodal focusing of surface and body waves from earthquakes is a well-known phenomenon which has previously been exploited by seismologists in studies of the Earth's deep interior. Antipodal focusing from impacts on the Moon, Mercury, and icy satellites has also been invoked by planetary scientists to explain unusual surface features opposite some of the large impact structures on these bodies. For example, 'disrupted' terrains have been observed antipodal to the Caloris impact basis on Mercury and Imbrium Basin on the Moon. Very recently there have been speculations that antipodal focusing of impact energy within the mantle may lead to flood basalt and hotspot activity, but there has not yet been an attempt at a rigorous model. A new hypothesis was proposed and preliminary proof-of-principle tests for the coupling of energy from major impacts to the mantle by axial focusing of seismic waves was performed. Because of the axial symmetry of the explosive source, the phases and amplitudes are dependent only on ray parameter (or takeoff angle) and are independent of azimuthal angle. For a symmetric and homogeneous Earth, all the seismic energy radiated by the impact at a given takeoff angle will be refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Mantle material near the axis of symmetry will experience more strain cycles with much greater amplitude than elsewhere and will therefore experience more irreversible heating. The situation is very different than for a giant earthquake, which in addition to having less energy, has an asymmetric focal mechanism and a larger area. Two independent proof-of-principle approaches were used. The first makes use of seismic simulations, which are being performed with a realistic Earth model to determine the degree of focusing along the axis and to estimate the volume of material, if any, that experiences significant irreversible heating. The second involves two-dimensional hydrodynamic code simulations to determine the stress history, internal energy, and temperature rise as a function of radius along the axis.

Boslough, M. B.↗

NASA NTRS1997

Exploring for Martian Life

Terrestrial life appears to have arisen very quickly during late accretion, sometime between approximately 3.5 and 4.2 Ga. During this same time, liquid water appears to have been abundant at the surface of Mars and it is quite plausable that life originated there as well. We now believe that the last common ancestor of terrestrial life was a sulfur-metabolizing microbe that lived at high temperatures. Rooting of the RNA tree in thermophily probably reflects high temperature "bottle-necking" of the biosphere by giant impacts during late accretion, sometime after life had originated. If high temperature bottle-necking is a general property of early biosphere development, Martian life may have also developed in close association with hydrothermal systems. Several independent lines of evidence suggest that hydrothermal processes have played an important role during the geological history of Mars. Because hydrothermal deposits on Earth are known to capture and retain abundant microbial fossil information, they are considered prime targets in the search for an ancient Martian biosphere. An important step in planning for future landed missions to Mars is the selection of priority targets for high resolution orbital mapping. Geotectonic terranes on Mars that provide a present focus for ongoing site selection studies include channels located along the margins of impact crater melt sheets, or on the slopes of ancient Martian volcanoes, chaotic and fretted terranes where shallow subsurface heat sources are thought to have interacted with ground ice, and the floors of calderas and rifted basins. Orbital missions in 1996, 1998 and 2001 will provide opportunities for high resolution geological mapping at key sites in such terranes, as a basis for selecting targets for future landed missions for exopaleontology.

Farmer, Jack D.↗

NASA NTRS2011

Simulation and Characterization of a Miniaturized Scanning Electron Microscope

A miniaturized Scanning Electron Microscope (mSEM) for in-situ lunar investigations is being developed at NASA Marshall Space Flight Center with colleagues from the University of Alabama in Huntsville (UAH), Advanced Research Systems (ARS), the University of Tennessee in Knoxville (UTK) and Case Western Reserve University (CWRU). This effort focuses on the characterization of individual components of the mSEM and simulation of the complete system. SEMs can provide information on the size, shape, morphology and chemical composition of lunar regolith. Understanding these basic properties will allow us to better estimate the challenges associated with In-Situ Resource Utilization and to improve our basic science knowledge of the lunar surface (either precluding the need for sample return or allowing differentiation of unique samples to be returned to Earth.) The main components of the mSEM prototype includes: a cold field emission electron gun (CFEG), focusing lens, deflection/scanning system and backscatter electron detector. Of these, the electron gun development is of particular importance as it dictates much of the design of the remaining components. A CFEG was chosen for use with the lunar mSEM as its emission does not depend on heating of the tungsten emitter (lower power), it offers a long operation lifetime, is orders of magnitude brighter than tungsten hairpin guns, has a small source size and exhibits low beam energy spread.

Gaskin, Jessica A.↗

NASA NTRS1999

Differences Between ERBE and CERES Tropical Means Fluxes: ENSO, Climate Change of Calibration?

Verner E. Soumi was the father of radiation budget measurements from space. He directed the team at the University of Wisconsin that developed the first radiation budget measurements on the Iota (Explorer VII) coverage) spacecraft in 1959. The first data published was from hand calculations of night-time long-wave fluxes, with absolute accuracy estimated as better than 10 percent, and the data shown as hand drawn maps with lines of equal "long-wave radiation loss, in Langleys per minute X 10(exp -3) (isolangleys)". The first comparisons of the new radiation data with nephanalyses showed that clouds dominated the radiation patterns. Soumi immediately proposed using the radiation fields to help understand the atmospheric heat sources necessary to drive the atmospheric circulation. This early work already pointed to the relationship between the outgoing longwave radiation at the top of the atmosphere and the vertical flux divergence of infrared radiation within the atmosphere. In the next 30 years, global satellite observations of the radiation balance of the planet have advanced both in accuracy, stability, and in their ability to address cause and effect in the climate system. The purpose of the present paper is to examine early results of the new Clouds and the Earth's Radiant Energy System (CERES) data on Tropical Rainfall Measuring System (TRMM) which started data collection in January, 1998. CERES is a direct descendant of the legacy of Soumi's foresight on understanding the global energetics using satellite observations of broadband radiation.

Wielicki, Bruce A.↗

NASA NTRS2005

Differences between ERBE and CERES Tropical Mean Fluxes: ENSO, Climate Change or Calibration?

Wielicki, Bruce A.↗

NASA NTRS2004

High Temperature mechanically pumped fluid loop for space applications - working fluid selection

Mechanically pumped single-phase fluid loops are increasingly being used for heat rejection purposes in space applications. Examples of Earth orbiting missions using this technology include NSTS Shuttles (water and Freon-based loops) and the International Space Station (water and ammonia-based loops). For deep space missions, both the Mars Pathfinder (1996) and Mars Exploration Rover (2003) missions used mechanically pumped Freon-I 1 loops for their primary Heat Rejection Systems (HRS.) Mechanically pumped loops are particularly well suited for rejecting large amounts of waste heat from spacecraft and future missions incorporating components with extremely high thermal energy dissipation (e.g. radar instruments, Radioisotope-based power sources) are ideal candidates for their use. However, previous implementations of mechanically pumped loops were designed for moderate temperatures (below 6OOC) and, thus, would require relatively large radiators to reject high heat loads to space. Loops designed for a higher operating temperature would allow large amounts of heat to be rejected within the constraints of a mass efficient thermal control system.

high temperature↗

NASA NTRSDate not supplied

Variations in radiative heating of humid biomass burning aerosols in the southeast Atlantic from airborne observations and reanalysis

The atmosphere over the southeast Atlantic Ocean (SEA) experiences consistent springtime biomass burning (BB) smoke from widespread agricultural fires on the African continent. This smoke layer is initially lofted high in a continental mixed layer (~5-6km) and is then transported westward into the free troposphere where it overlies and ultimately mixes into a stratocumulus-topped oceanic boundary layer. Coincident with this smoke is an elevated humidity signal which is present from the time a given airmass is over the continental source region. ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) was a NASA Earth Venture Suborbital mission with the goal of measuring aerosol, cloud, and atmospheric properties over this region over three deployments in September 2016, August 2017, and October 2018. Measurements included in situ profile measurements of aerosol physical and optical properties, trace gas concentrations, and cloud properties, as well as column measurements of aerosol optical depth and trace gas concentrations from an airborne sun photometer. Here we present results from each of the ORACLES deployments over the southeast Atlantic Ocean. Despite the differing locations and season of each deployment, we show that there is good agreement between the airborne ORACLES dataset and large-scale reanalyses, specifically the ECMWF ERA5 reanalyses (and, to a degree, the CAMS product) as compared to other available products. This agreement allows us to examine multi-year seasonal patterns and trends beyond the three months with available aircraft data. In both the data and reanalysis, we find distinct variations between each deployment in terms of vertical smoke distribution and correlation to atmospheric specific humidity, due to changing conditions over the BB season. We trace the origin and the history of these smoky airmasses and finally, we briefly discuss the broader radiative and dynamical implications of these results for conditions of aerosols overlying stratocumulus clouds.

K. Pistone↗