Discovery of a transient U-band dropout in a Lyman break survey: a tidally-disrupted star at z = 3.3.?
We report the discovery of a transient source in the central regions of galaxy cluster Abell 267.
Lyman-break↗
SEARCH · Engineering Papers
Results for “U”
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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Development and Certification of Station Development Test Objective (SDTO) Experiment # 15012-U, "Near RealTime Water Quality Monitoring Demonstration for ISS Biocides Using Colorimetric Solid Phase Extraction (CSPE)"
Scientists and engineers from the Wyle Integrated Science and Engineering Group are working with researchers at the University of Utah and Iowa State University to develop and certify an experimental water quality monitoring kit based on Colorimetric Solid Phase Extraction (CSPE). The kit will be launched as a Station Development Test Objective (SDTO) experiment and evaluated on the International Space Station (ISS) to determine the acceptability of CSPE technology for routine inflight water quality monitoring. Iodine and silver, the biocides used in the US and Russian on-orbit water systems, will serve as test analytes for the technology evaluation. This manuscript provides an overview of the CSPE SDTO experiment and details the development and certification of the experimental water quality monitoring kit. Initial results from reagent and standard solution stability testing and environmental testing performed on the kit hardware are also reported.
Gazda, Daniel B.↗
Diagnosing the Nature of Land-Atmosphere Coupling During the 2006-7 Dry/Wet Extremes in the U. S. Southern Great Plains
The degree of coupling between the land surface and PBL in NWP models remains largely undiagnosed due to the complex interactions and feedbacks present across a range of scales. In this study, a framework for diagnosing local land-atmosphere coupling (LoCo) is presented using a coupled mesoscale model with observations during the summers of 2006/7 in the U.S. Southern Great Plains. Specifically, the Weather Research and Forecasting (WRF) model has been coupled to NASA's Land Information System (LIS), which enables a suite of PBL and land surface model (LSM) options along provides a flexible and high-resolution representation and initialization of land surface physics and states. This coupling is one component of a larger project to develop a NASA-Unified WRF (NU-WRF) system. A range of diagnostics exploring the feedbacks between soil moisture and precipitation are examined for the dry/wet extremes, along with the sensitivity of PBL-LSM coupling to perturbations in soil moisture.
Santanello, Joseph A., Jr.↗
Diagnosing the Nature of Land-Atmosphere Coupling During the 2006-7 Dry/Wet Extremes in the U. S. Southern Great Plains
Land-atmosphere (L-A) interactions play a critical role in determining the diurnal evolution of land surface and planetary boundary layer (PBL) temperature and moisture states and fluxes. In turn, these interactions regulate the strength of the connection between surface moisture and precipitation in a coupled system. To address deficiencies in numerical weather prediction and climate models due to improper treatment of L-A interactions, recent studies have focused on development of diagnostics to quantify the strength and accuracy of the land-PBL coupling at the process-level. In this study, a diagnosis of the nature and impacts of local land-atmosphere coupling (LoCo) during dry and wet extreme conditions is presented using a combination of models and observations during the summers of2006-7 in the U.S. Southern Great Plains. Specifically, the Weather Research and Forecasting (WRF) model has been coupled to NASA's Land Information System (LIS), which provides a flexible and high resolution representation and initialization of land surface physics and states. A range of diagnostics exploring the links and feedbacks between soil moisture and precipitation are examined for the dry/wet regimes of this region, along with the behavior and accuracy of different land-PBL scheme couplings under these conditions. Results demonstrate how LoCo diagnostics can be applied to coupled model components in the context of their integrated impacts on the process-chain connecting the land surface to the PBL and support of hydrological anomalies.
Santanello, Joseph A.↗
Diagnosing the Nature of Land-Atmosphere Coupling: A Case Study of Dry/Wet Extremes in the U. S. Southern Great Plains
Land-atmosphere (L-A) interactions play a critical role in determining the diurnal evolution of land surface and planetary boundary layer (PBL) temperature and moisture states and fluxes. In turn, these interactions regulate the strength of the connection between surface moisture and precipitation in a coupled system. To address model deficiencies, recent studies have focused on development of diagnostics to quantify the strength and accuracy of the land- PBL coupling at the process-level. In this paper, a diagnosis of the nature and impacts of local land-atmosphere coupling (LoCo) during dry and wet extreme conditions is presented using a combination of models and observations during the summers of 2006 and 2007 in the U.S. Southern Great Plains. A range of diagnostics exploring the links and feedbacks between soil moisture and precipitation are applied to the dry/wet regimes exhibited in this region, and in the process a thorough evaluation of nine different land-PBL scheme couplings is conducted under the umbrella of a high-resolution regional modeling testbed. Results show that the sign and magnitude of errors in land surface energy balance components are sensitive to the choice of land surface model, regime type, and running mode. In addition, LoCo diagnostics show that the sensitivity of L-A coupling is stronger towards the land during dry conditions, while the PBL scheme coupling becomes more important during the wet regime. Results also demonstrate how LoCo diagnostics can be applied to any modeling system (e.g. reanalysis products) in the context of their integrated impacts on the process-chain connecting the land surface to the PBL and in support of hydrological anomalies.
Santanello, Joseph A. Jr.↗
The Impacts of Microphysics and Planetary Boundary Layer Physics on Model Simulations of U. S. Deep South Summer Convection
Inspection of output from various configurations of high-resolution, explicit convection forecast models such as the Weather Research and Forecasting (WRF) model indicates significant sensitivity to the choices of model physics parameterizations employed. Some of the largest apparent sensitivities are related to the specifications of the cloud microphysics and planetary boundary layer physics packages. In addition, these sensitivities appear to be especially pronounced for the weakly-sheared, multicell modes of deep convection characteristic of the Deep South of the United States during the boreal summer. Possible ocean-land sensitivities also argue for further examination of the impacts of using unique ocean-land surface initialization datasets provided by the NASA Short-term Prediction Research and Transition (SPoRT Center to select NOAA/NWS weather forecast offices. To obtain better quantitative understanding of these sensitivities and also to determine the utility of the ocean-land initialization data, we have executed matrices of regional WRF forecasts for selected convective events near Mobile, AL (MOB), and Houston, TX (HGX). The matrices consist of identically initialized WRF 24-h forecasts using any of eight microphysics choices and any of three planetary boundary layer choices. The resulting 24 simulations performed for each event within either the MOB or HGX regions are then compared to identify the sensitivities of various convective storm metrics to the physics choices. Particular emphasis is placed on sensitivities of precipitation timing, intensity, and coverage, as well as amount and coverage of lightning activity diagnosed from storm kinematics and graupel in the mixed phase layer. The results confirm impressions gleaned from study of the behavior of variously configured WRF runs contained in the ensembles produced each spring at the Center for the Analysis and Prediction of Storms, but with the benefit of more straightforward control of the physics package choices. The design of the experiments thus allows for more direct interpretation of the sensitivities to each possible physics combination. The results should assist forecasters in their efforts to anticipate and correct for possible biases in simulated WRF convection patterns, and help the modeling community refine their model parameterizations.
McCaul, E. W., Jr.↗
The U. S. Space Program -- An Appraisal
The National Aeronautics and Space Administration has a significant interest in research on magnetic materials and in developing a better understanding of magnetic phenomena here on earth, in space and in the vicinity of the other planets of our solar system. But it would be presumptuous of me, an ordinary administrator, to lecture to this distinguished group of experts in the field on the subject of magnetism and magnetic materials. Instead, I propose to tell you briefly about the dimensions and principal areas of effort of the program we are pursuing in space research. Naturally, I will identify the nature of our interest in the specialty with which you are concerned. Finally, I want to attempt an assessment of the United States program in space exploration with perhaps a sidelong glance at the comparable efforts of our principal competitor in this field -- the Soviet Union. In the preparation of this paper, I have had the assistance of several very able scientists who are members of our staff at NASA.
Glennan, T. Keith↗
Where are the Shocked Grains in the Hadean Zircon Record? Insights on the Preservation of Shocked Zircon and Their U-Pb Systematics
While the earliest history of many planetary bodies within the inner Solar System is dominated by intense bombardment, this record is missing from Earth due to active tectonics and erosion. Where-as rocks from the earliest history of Earth are absent, mineral relics, such as ancient detrital zircon concentrated in sediments within the Jack Hills, Narryer, Illara and Maynard Hills greenstone belts of the Yilgarn Craton in Western Australia preserve a record of this time.Shock in zircon: During shock deformation, resulting from hyper-velocity impact, zircon can be modified in crystallographically-controlled ways. This includes the development of planar and subplanar low-angle grain boundaries, the formation of mechanical twins, transformation to the high pressure polymorph reidite, development of polycrystalline microtexture, and dissociation to its dioxide constituents SiO2 and ZrO2.
Erickson, T. M.↗
Flight Determined Longitudinal and Lateral-Directional Derivatives of the YF-12A Airplane (U)
No abstract available
Gilyard, Glenn B↗
u-Spec Spectrometers for the EXCLAIM Instrument
The EXperiment for Cryogenic Large-aperture Intensity Mapping (EXCLAIM) is a cryogenic balloon-borne instrument that will map carbon monoxide and singly-ionized carbon emission lines across redshifts from 0to 3.5, using an intensity mapping approach. EXCLAIM will broaden our understanding of these elemental and molecular gases, and the role they play in star formation processes across cosmic time scales. The focal plane of EXCLAIM’s cryogenic telescope features sixμ-Spec spectrometers.μ-Spec is a compact, integrated grating-analog spectrometer, which uses meandered superconducting niobium microstrip transmission lines on a single-crystal silicon dielectric to synthesize the grating. It features superconducting aluminum microwave kinetic inductance detectors (MKIDs), also in a microstrip architecture. The spectrometers for EXCLAIM couple to the telescope optics via a hybrid planar antenna coupled to a silicon lenslet. The spectrometers operate from420−540 GHz with a resolving power R=λ/∆λ= 512, and employ an array of 355 MKIDs on each spectrometer. The spectrometer design targets a noise equivalent power (NEP) of 2×10−18W/√Hz (defined at the input to the main lobe of the spectrometer lenslet beam, within a 9◦half width), enabled by the cryogenic telescope environment, the sensitive MKID detectors, and the low dielectric loss of single-crystal silicon. We report on these spectrometers under development for EXCLAIM, providing an overview of the spectrometer and component designs, the spectrometer fabrication process, fabrication developments since previous prototype demonstrations, and the current status of their development for the EXCLAIM mission.
EXCLAIM Instrument↗
The Fall 2019 Southeast U. S. Flash Drought: An Extreme Event Driven by an Extreme Positive Indian Ocean Dipole
Explore the source record for details and available documents.
Drought↗
On the Development and Demise of the Fall 2019 Southeast U. S. Flash Drought: Links to an Extreme Positive IOD
Much of the southeast United States experienced record dry conditions during September of 2019, with the area in abnormally dry to exceptional drought conditions growing from 25% at the beginning of the month to 80% by the end of the month. The drought ended just as abruptlydue to above normal rain that fell during the second half of October. In this study we employed MERRA-2 and the GEOS-5 AGCM to diagnose the underlying causes of the drought’s onset, maintenance, and demise. The basic approach involves performing a series of AGCM simulations in which the model is constrained to remain close to MERRA-2 over pre-specified areas that are external to the drought region. The start of the drought appears to have been forced by anomalous heating in the central/western tropical Pacific that resulted in low level anti-cyclonic flow and a tendency for descending motion over much of the southeast. An anomalous ridge associated with a Rossby wave train (emanating from the Indian Ocean region) is found to be the main source of the most intense temperature and precipitation anomalies that develop over the southeast during the last week of September. A second Rossby wave train (emanating from the same region) is responsible for the substantial rain that fell during the second half of October to end the drought. The links to the Indian Ocean Dipole (with record positive values) as well a sa waning El Nino allow some speculation as to the likelihood of similar events occurring in the future.
Siegfried D Schubert↗
Connecting NASA Capabilities and Water Resources Needs in the Western U. S.
UNKNOWN
Granger, Stephanie↗
The Effects of Hot Hydrogen Exposure on Bicarbide (U,Zr)C Fuel for Nuclear Thermal Propulsion
Explore the source record for details and available documents.
refractory carbides↗
Successful First Flight of NASA’s SLS (Space Launch System) Super Heavy-Lift Rocket Lays Groundwork for U. S.’s Most Ambitious Missions
In late 2022, NASA’s SLS (Space Launch System) super heavy-lift rocket launched for the first time. Artemis I sent an uncrewed Orion spacecraft on a 25.5-day round-trip mission to lunar orbit. The near-perfect performance laid the groundwork for the next flights and for NASA’s return of humans to the Moon. The SLS team is now preparing for the launch of Artemis II, which will be the first launch of astronauts to cislunar space since Apollo 17 in December 1972. In addition to preparations on the Artemis II launch vehicle, significant progress is being made on the hardware and software for future flights. Artemis II will include a test of a new military-grade GPS system, which will be fully utilized on Artemis III. Progress is also being made on the exploration upper stage (EUS) for the Block 1B SLS variant, which will debut on Artemis IV. New production RS-25 liquid-propellant engines will be used beginning with Artemis V. These new engines, which are in a final qualification test firing program at the time of writing, realize a cost savings of at least 30 percent and reduced production time due to streamlined manufacturing and advances in technology, including additive manufacturing. The evolved solid rocket boosters, which will debut on Artemis IX as part of the Block 2 variant, are in development now. In addition to propulsion updates, each variant of SLS maintains payload configuration flexibility and can fly crew-only, cargo-only, and crew-cargo combinations. This adaptability ensures that SLS, with its significant mass and volume capability – including the ability to launch large co-manifested payloads with Orion directly to trans-lunar injection (TLI) – can support the country’s most ambitious missions. Results from the Artemis I mission, as well as progress to the next flights and SLS variants, will be covered in the paper and presentation.
Bruce R. Askins↗
Successful First Flight of NASA’s SLS (Space Launch System) Super Heavy-Lift Rocket: Laying Groundwork for U. S.’s Most Ambitious Missions
In late 2022, NASA’s SLS (Space Launch System) super heavy-lift rocket launched for the first time. Artemis I sent an uncrewed Orion spacecraft on a 25.5-day round-trip mission to lunar orbit. The near-perfect performance laid the groundwork for the next flights and for NASA’s return of humans to the Moon. The SLS team is now preparing for the launch of Artemis II, which will be the first launch of astronauts to cislunar space since Apollo 17 in December 1972. In addition to preparations on the Artemis II launch vehicle, significant progress is being made on the hardware and software for future flights. Artemis II will include a test of a new military-grade GPS system, which will be fully utilized on Artemis III. Progress is also being made on the exploration upper stage (EUS) for the Block 1B SLS variant, which will debut on Artemis IV. New production RS-25 liquid-propellant engines will be used beginning with Artemis V. These new engines, which are in a final qualification test firing program at the time of writing, realize a cost savings of at least 30 percent and reduced production time due to streamlined manufacturing and advances in technology, including additive manufacturing. The evolved solid rocket boosters, which will debut on Artemis IX as part of the Block 2 variant, are in development now. In addition to propulsion updates, each variant of SLS maintains payload configuration flexibility and can fly crew-only, cargo-only, and crew-cargo combinations. This adaptability ensures that SLS, with its significant mass and volume capability – including the ability to launch large co-manifested payloads with Orion directly to trans-lunar injection (TLI) – can support the country’s most ambitious missions. Results from the Artemis I mission, as well as progress to the next flights and SLS variants, will be covered in the paper and presentation.
Bruce Askins↗