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All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

A determination of the masses of Ceres, Pallas, and Vesta from their perturbations upon the orbit of Mars

Measurements of Mars-orbit perturbations have been conducted in order to estimate the masses of the Ceres, Pallas, and Vesta asteroids. A full, least-squares adjustment of all ephemeris parameters, including the relevant asteroid masses, is compiled on the basis of observational data encompassing the highly accurate Viking Lander ranging data. The mass for Ceres, of 5.0 + or - 0.2 x 10 to the -10th solar masses, that for Pallas, of 1.4 + or - 0.2 x 10 to the -10th solar masses, and that for Vesta, of 1.5 + or - 0.3 x 10 to the -10th solar masses, respectively represent 15, 30, and 9 percent increases over Schubart's (1970, 1974, 1975) previous determinations.

Standish, E. Myles, Jr.↗
NASA NTRS1995

Bibliography of Doctor Chul Park

This document contains a comprehensive bibliography of the published works, and a short biography, of Dr. Chul Park. The contents of this bibliography were compiled primarily from the NASA RECON data base. The RECON citations have been modified to appear in a uniform format with all other listed citations . These other citations were located by computer searches in the INSPEC, NTIS, COMPENDEX, and Chemical Abstracts data bases, as well as through the cooperation of Dr. Chul Park, and his associates in the Reacting Flow Environments Branch at NASA Ames Research Center. All citations are presented in an approximate reverse chronological order from the present date. This work was created to honor the occasion of Dr. Chul Park's retirement on December 14, 1994, after 27 years of distinguished government service at the NASA Ames Research Center.

Gochberg, Lawrence A.↗
NASA NTRS1995

Statistical studies of impulsive events at high latitudes

A statistical study has been made of the high-latitude impulsive events that were observed during the 1985-1986 South Pole Balloon Campaign. The events were selected by searching for unipolar pulses greater than or equal to 10 nT above background in the vertical component of the magnetic field on the ground and/or pedestal or 'W' shaped horizontal electric field perturbations greater than or equal to 10 mV/m in amplitude and accompanied by perturbations in the vertical electric field at balloon altitude. A main event list comprising 112 events was compiled from the 468 hours of data available. Three aspects of the events were examined: the solar wind conditions prior to the event, local time of observation, and intrinsic properties of the events. The local time distribution was obtained from the 112 entry main event list and was found to be nearly uniform across the dayside, with no midday gap. The event rate found using our low-amplitude selection criteria was 0.7 event/hr, comparable to expectations based on in situ studies of the magnetopause. A total of 42 events were found for which data were available from Interplanetary Monitoring Platform (IMP) 8. Of these events, 12 occurred when the Z(sub GSM) component (B(sub Z)) of the interplanetary magnetic field (IMF) was northward and 30 occurred when B(sub Z) was southward or fluctuating. Only three of the B(sub Z) northward cases and only five of the B(sub Z) southward cases were preceded by pressure pulses greater than 0.4 nPa in amplitude. Ten of the events were studied in detail by means of a model-fitting method discussed elsewhere. This method infers values of several parameters, including the total current flowing in a coaxial or monopole system and a two-dimensional dipole system. The intrinsic properties of the events showed that only approximately 10% of the total current contributed to momentum transfer to the high-latitude ionosphere, that the direction of the motion depended more on local time of observation than IMF B(sub y), and that events were usually several hundred kilometers in size. The observed B(sub z) control found in the 42 event list and the prevalence of coaxial current dominated events are inconsistent with the predictions of the pressure pulse model.

Lin, Z. M.↗
NASA NTRS1999

Mars Observer Propulsion and Pyrotechnics Corrective Actions Test Program Status-1999

An extensive propulsion and pyrotechnic test program has been in progress at the NASA White Sands Test Facility since 1995. This program created the capabilities to: accurately measure and characterize pyrovalve combustion product blow-by into propellant systems; characterize valve operation using a Velocity Interferometer System for Any Reflector (VISAR); and evaluate hydrazine and monomethylhydrazine thermal decomposition initiated by blow-by. These capabilities were further utilized and refined this year. Low blow-by pyrovalves manufactured by Conax Florida Corporation continued to be evaluated as a potential corrective measure for blow-by induced propellant explosions. Development and testing of various advanced pyrovalves and investigation of explosion mechanisms also continued. Current and near-term testing includes: evaluation of 3/8 in. Conax pyrovalves and other commercially available valves; development and testing of advanced pyrovalve subcomponent technologies including a zero blow-by pyrovalve ram, composite overwrapped ram cylinder, and a zero particulate generating poppet; investigation of non-destructive evaluation techniques to evaluate pyrovalve ram seals; and testing and modeling of pyrotechnically induced explosive hydrazine decomposition. Evaluation of 3/8 in. Conax valves will include operational margin testing to be accomplished at NASA Langley Research Center. The test program also seeks to compile and format significant amounts of data from this and other pyrovalve test programs to generate a pyrovalve applications handbook. The handbook will facilitate formation of standards that ensure safe spacecraft applications. Current data and future plans are discussed, and community interaction is encouraged.

Saulsberry, Regor↗
NASA NTRS2005

The Distribution of Cloud to Ground Lightning Strike Intensities and Associated Magnetic Inductance Fields Near the Kennedy Space Center

Lightning strike location and peak current are monitored operationally in the Kennedy Space Center (KSC) Cape Canaveral Air Force Station (CCAFS) area by the Cloud to Ground Lightning Surveillance System (CGLSS). The present study compiles ten years worth of CGLSS data into a database of near strikes. Using shuffle launch platform LP39A as a convenient central point, all strikes recorded within a 20-mile radius for the period of record O R ) from January 1, 1993 to December 31,2002 were included in the subset database. Histograms and cumulative probability curves are produced for both strike intensity (peak current, in kA) and the corresponding magnetic inductance fields (in A/m). Results for the full POR have application to launch operations lightning monitoring and post-strike test procedures.

Burns, Lee↗
NASA NTRS2009

Space Shuttle Usage of z/OS

This viewgraph presentation gives a detailed description of the avionics associated with the Space Shuttle's data processing system and its usage of z/OS. The contents include: 1) Mission, Products, and Customers; 2) Facility Overview; 3) Shuttle Data Processing System; 4) Languages and Compilers; 5) Application Tools; 6) Shuttle Flight Software Simulator; 7) Software Development and Build Tools; and 8) Fun Facts and Acronyms.

Green, Jan↗
NASA NTRS2010

Asbestos Exposure Assessment Database

Exposure to particular hazardous materials in a work environment is dangerous to the employees who work directly with or around the materials as well as those who come in contact with them indirectly. In order to maintain a national standard for safe working environments and protect worker health, the Occupational Safety and Health Administration (OSHA) has set forth numerous precautionary regulations. NASA has been proactive in adhering to these regulations by implementing standards which are often stricter than regulation limits and administering frequent health risk assessments. The primary objective of this project is to create the infrastructure for an Asbestos Exposure Assessment Database specific to NASA Johnson Space Center (JSC) which will compile all of the exposure assessment data into a well-organized, navigable format. The data includes Sample Types, Samples Durations, Crafts of those from whom samples were collected, Job Performance Requirements (JPR) numbers, Phased Contrast Microscopy (PCM) and Transmission Electron Microscopy (TEM) results and qualifiers, Personal Protective Equipment (PPE), and names of industrial hygienists who performed the monitoring. This database will allow NASA to provide OSHA with specific information demonstrating that JSC s work procedures are protective enough to minimize the risk of future disease from the exposures. The data has been collected by the NASA contractors Computer Sciences Corporation (CSC) and Wyle Laboratories. The personal exposure samples were collected from devices worn by laborers working at JSC and by building occupants located in asbestos-containing buildings.

Arcot, Divya K.↗
NASA NTRS2006

Logistics Lessons Learned in NASA Space Flight

The Vision for Space Exploration sets out a number of goals, involving both strategic and tactical objectives. These include returning the Space Shuttle to flight, completing the International Space Station, and conducting human expeditions to the Moon by 2020. Each of these goals has profound logistics implications. In the consideration of these objectives,a need for a study on NASA logistics lessons learned was recognized. The study endeavors to identify both needs for space exploration and challenges in the development of past logistics architectures, as well as in the design of space systems. This study may also be appropriately applied as guidance in the development of an integrated logistics architecture for future human missions to the Moon and Mars. This report first summarizes current logistics practices for the Space Shuttle Program (SSP) and the International Space Station (ISS) and examines the practices of manifesting, stowage, inventory tracking, waste disposal, and return logistics. The key findings of this examination are that while the current practices do have many positive aspects, there are also several shortcomings. These shortcomings include a high-level of excess complexity, redundancy of information/lack of a common database, and a large human-in-the-loop component. Later sections of this report describe the methodology and results of our work to systematically gather logistics lessons learned from past and current human spaceflight programs as well as validating these lessons through a survey of the opinions of current space logisticians. To consider the perspectives on logistics lessons, we searched several sources within NASA, including organizations with direct and indirect connections with the system flow in mission planning. We utilized crew debriefs, the John Commonsense lessons repository for the JSC Mission Operations Directorate, and the Skylab Lessons Learned. Additionally, we searched the public version of the Lessons Learned Information System (LLIS) and verified that we received the same result using the internal version of LLIS for our logistics lesson searches. In conducting the research, information from multiple databases was consolidated into a single spreadsheet of 300 lessons learned. Keywords were applied for the purpose of sorting and evaluation. Once the lessons had been compiled, an analysis of the resulting data was performed, first sorting it by keyword, then finding duplication and root cause, and finally sorting by root cause. The data was then distilled into the top 7 lessons learned across programs, centers, and activities.

Evans, William A.↗
NASA NTRS2012

A Functional Comparison of Lunar Regoliths and Their Simulants

Lunar regolith simulants are essential to the development of technology for human exploration of the Moon. Any equipment that will interact with the surface environment must be tested with simulant to mitigate risk. To reduce the greatest amount of risk, the simulant must replicate the lunar surface as well as possible. To quantify the similarities and differences between simulants, the Figures of Merit were developed. The Figures of Merit software compares the simulants and regolith by particle size, particle shape, density, and bulk chemistry and mineralogy; these four properties dictate the majority of the remaining characteristics of a geologic material. There are limitations to both the current Figures of Merit approach and simulants in general. The effect of particle textures is lacking in the Figures of Merit software, and research into this topic has only recently begun with applications to simulants. In addition, not all of the properties for lunar regolith are defined sufficiently for simulant reproduction or comparison; for example, the size distribution of particles greater than 1 centimeter and the makeup of particles less than 10 micrometers is not well known. For simulants, contamination by terrestrial weathering products or undesired trace phases in feedstock material is a major issue. Vapor deposited rims have not yet been created for simulants. Fortunately, previous limitations such as the lack of agglutinates in simulants have been addressed and commercial companies are now making agglutinate material for simulants. Despite some limitations, the Figures of Merit sufficiently quantify the comparison between simulants and regolith for useful application in lunar surface technology. Over time, the compilation and analysis of simulant user data will add an advantageous predictive capability to the Figures of Merit, accurately relating Figures of Merit characteristics to simulant user parameters.

Rickman, D.↗
NASA NTRSDate not supplied

Machine Learning Applications to Metal-Silicate Equilibria and their Insights into Core Formation

An extensive number of studies have experimentally investigated how elements distribute between metal and silicate phases, to better constrain core-mantle chemical equilibrium. Here, we present a new database compiling all (to our knowledge) experimental data on liquid metal-silicate partitioning from 118 peer-reviewed publications. We applied various machine learning techniques to gain further insights into these partitioning equilibria and their dependencies. We performed a network analysis to investigate the relationship between experiments and partition coefficients, which enables visualizing gaps in the experimental dataset and biases related to varying experimental conditions and analytical setup. In addition, semi-empirical thermodynamic models are commonly used to extrapolate these chemical reactions to the wide range of pressure, temperature and compositional conditions of planetary differentiation. These models are based on linear regressions that assume continuous relationship between partition coefficients and experimental variables. Here, we considered random forest regressions, which are algorithms based on ensembles of decision trees and does not consider continuous effects of each variable. The application of this regression significantly improves the prediction of metal-silicate partitioning for several elements including Ni, Si and Cr. We will show how this new approach improves our understanding of elemental exchange between metal and silicate and their implications for the Earth’s core formation.

siderophile element↗
NASA NTRS1992

Simulation and analysis of support hardware for multiple instruction rollback

Recently, a compiler-assisted approach to multiple instruction retry was developed. In this scheme, a read buffer of size 2N, where N represents the maximum instruction rollback distance, is used to resolve one type of data hazard. This hardware support helps to reduce code growth, compilation time, and some of the performance impacts associated with hazard resolution. The 2N read buffer size requirement of the compiler-assisted approach is worst case, assuring data redundancy for all data required but also providing some unnecessary redundancy. By adding extra bits in the operand field for source 1 and source 2 it becomes possible to design the read buffer to save only those values required, thus reducing the read buffer size requirement. This study measures the effect on performance of a DECstation 3100 running 10 application programs using 6 read buffer configurations at varying read buffer sizes.

Alewine, Neil J.↗
DOE OSTI2023

Tonian Carbonates Record Phosphate-Rich Shallow Seas

The early-middle Neoproterozoic is thought to have witnessed significant perturbations to marine P cycling, in turn facilitating the rise of eukaryote-dominated primary production. However, with few robust constraints on aqueous P concentrations, current understanding of Neoproterozoic P cycling is generally model-dependent. To provide new geochemical constraints, we combined microanalytical data sets with solid-state Nuclear Magnetic Resonance, synchrotron-based X-ray Absorption Near Edge Structure spectroscopy, and micro-X-ray Fluorescence imaging to characterize the speciation and distribution of P in Tonian shallow-water carbonate rocks. These data reflect shallow water phosphate concentrations 10–100× higher than modern systems, supporting the hypothesis that tectonically-driven influxes in P periodically initiated kinetically-controlled CaCO 3 deposition, in turn destabilizing marine carbonate chemistry, climate, and nutrient inventories. Alongside these observations, a new compilation and statistical analysis of mudstone geochemistry data indicates that, in parallel, C org and P burial increased across later Tonian continental margins until becoming decoupled at the close of the Tonian, implicating widespread N-limitation triggered by increasing atmospheric O 2 .

58 GEOSCIENCES↗
DOE OSTI2026

Estimating Fine-Resolution Shortwave Broadband Albedo of Croplands from Harmonized Landsat and Sentinel-2 Data

Altered surface albedo due to land-cover conversions and management is a significant driver of global climate change. Albedo can be directly measured at ground stations, and remote sensing data can be used to scale-up albedo values to regional and global levels. Some previous studies have retrieved fine-resolution (10–30 m) instantaneous albedo and coarse-resolution (500–1000 m) daily mean albedo from remote sensing data, but they all required the input of Moderate Resolution Imaging Spectroradiometer (MODIS) albedo information at 500-m resolution, and none have assembled both instantaneous and daily albedo based exclusively on fine-resolution satellite data. Here, to address this issue, we compiled 387 instantaneous and 346 daily albedo records using field net radiometer measurements from the bioenergy croplands at the W. K. Kellogg Biological Station in southwest Michigan. We then connected these albedo records with a suite of variables derived from harmonized Landsat and Sentinel-2 data through two machine learning algorithms (random forest regression and extreme gradient boosting) to retrieve clear-sky instantaneous and daily shortwave broadband albedo. The performance statistics indicate reasonable accuracy of model results [root-mean-square error (RMSE)] around or below 0.03 except for snow-covered surfaces), suggesting that the retrieval of both instantaneous and daily albedo based exclusively on fine-resolution satellite data is promising. To facilitate the use of fine-resolution albedo products at the global level, future efforts need to include more albedo records of diverse surface cover types, as well as to accurately model daily albedo for cloudy days to address the “clear-sky bias.”

Harmonized Landsat and Sentinel-2↗
DOE OSTI2022

ESS-DIVE Reporting Format for Dataset Package Metadata

ESS-DIVE’s (Environmental Systems Science Data Infrastructure for a Virtual Ecosystem) dataset metadata reporting format is intended to compile information about a dataset (e.g., title, description, funding sources) that can enable reuse of data submitted to the ESS-DIVE data repository. The files contained in this dataset include instructions (dataset_metadata_guide.md and README.md) that can be used to understand the types of metadata ESS-DIVE collects. The data dictionary (dd.csv) follows ESS-DIVE’s file-level metadata reporting format and includes brief descriptions about each element of the dataset metadata reporting format. This dataset also includes a terminology crosswalk (dataset_metadata_crosswalk.csv) that shows how ESS-DIVE’s metadata reporting format maps onto other existing metadata standards and reporting formats.Data contributors to ESS-DIVE can provide this metadata by manual entry using a web form or programmatically via ESS-DIVE’s API (Application Programming Interface). A metadata template (dataset_metadata_template.docx or dataset_metadata_template.pdf) can be used to collaboratively compile metadata before providing it to ESS-DIVE.Since being incorporated into ESS-DIVE’s data submission user interface, ESS-DIVE’s dataset metadata reporting format, has enabled features like automated metadata quality checks, and dissemination of ESS-DIVE datasets onto other data platforms including Google Dataset Search and DataCite.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1978

LACIE (Large Area Crop Inventory Experiment) Programme

Large Area Crop Inventory Experiment was a three year experiment conducted jointly by the United States Department of Agriculture, NASA, and NOAA (National Oceanic and Atmospheric Administration) to determine if global wheat production can be forecast from LANDSAT data to within 90% of actual yield for each observed 9 years out of 10. Data for the third crop year (1976-1977) was compiled. The proportional area of cultivated land devoted to wheat was estimated based on a statistical sampling of LANDSAT data. Yield is presently estimated by NOAA using regression models developed from historical weather and yield information. Results are discussed.

Whitman, R. I.↗
DOE OSTI2022

Nuclear Data Sheets for A=48

Experimental nuclear structure data from various reactions and decays are compiled and evaluated for all known nuclides with mass number A=48 (S, Cl, Ar, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni). For each nuclide, detailed evaluated nuclear structure information is presented for each individual reaction and decay, and the best values combining all available data are recommended for spectroscopic properties, such as level energies, half-lives, γ-ray energies and intensities, decay radiations. No excited states have been identified in 48 S, 48 Cl, 48 Co and 48 Ni, among which the first three even have no measured ground-state half-lives and decay modes. For 48 Fe, a level scheme with a sequence of excited states was established for the first time from a recent one-neutron removal measurement by 2021Ya33. Data for excited states in 48 Ar, 48 K and 48 Mn remain limited; no decay scheme has been measured for 48 Ar and 48 K yet, while the decay scheme for 48 Ni is incomplete due to unobserved levels. 48 Ti is the most studied nuclide through various reactions and decays, followed by 48 V, 40 Ca, 48 Sc, and 48 Cr, among which no decay event to 48 Sc has been observed and the decay schemes for 48 V and 48 Cr are considered as incomplete. Furthermore, this work supersedes the previous full evaluations of A=48: 2006Bu08, 1993Bu04, 1985Al14, 1978Be01.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Using MLIR Framework for Codesign of ML Architectures Algorithms and Simulation Tools

MLIR (Multi-Level Intermediate Representation), is an extensible compiler framework that supports high-level data structures and operation constructs. These higher-level code representations are particularly applicable to the artificial intelligence and machine learning (AI/ML) domain, allowing developers to more easily support upcoming heterogeneous AI/ML accelerators and develop flexible domain specific compilers/frameworks with higher-level intermediate representations (IRs) and advanced compiler optimizations. The result of using MLIR within the LLVM compiler framework is expected to yield significant improvement in the quality of generated machine code, which in turn will result in improved performance and hardware efficiency

97 MATHEMATICS AND COMPUTING↗