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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 1,243 records · Page 69

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NASA NTRS2004

Multipurpose Crew Restraints for Long Duration Space Flights

With permanent human presence onboard the International Space Station (ISS), a crew will be living and working in microgravity, interfacing with their physical environment. Without optimum restraints and mobility aids (R&MA' s), the crewmembers may be handicapped for perfonning some of the on-orbit tasks. In addition to weightlessness, the confined nature of a spacecraft environment results in ergonomic challenges such as limited visibility and access to the activity area and may cause prolonged periods of unnatural postures. Thus, determining the right set of human factors requirements and providing an ergonomically designed environment are crucial to astronauts' well-being and productivity. The purpose of this project is to develop requirements and guidelines, and conceptual designs, for an ergonomically designed multi-purpose crew restraint. In order to achieve this goal, the project would involve development of functional and human factors requirements, design concept prototype development, analytical and computer modeling evaluations of concepts, two sets of micro gravity evaluations and preparation of an implementation plan. It is anticipated that developing functional and design requirements for a multi-purpose restraint would facilitate development of ergonomically designed restraints to accommodate the off-nominal but repetitive tasks, and minimize the performance degradation due to lack of optimum setup for onboard task performance. In addition, development of an ergonomically designed restraint concept prototype would allow verification and validation of the requirements defined. To date, we have identified "unique" tasks and areas of need, determine characteristics of "ideal" restraints, and solicit ideas for restraint and mobility aid concepts. Focus group meetings with representatives from training, safety, crew, human factors, engineering, payload developers, and analog environment representatives were key to assist in the development of a restraint concept based on previous flight experiences, the needs of future tasks, and crewmembers' preferences. Also, a catalog with existing IVA/EVA restraint and mobility aids has been developed. Other efforts included the ISS crew debrief data on restraints, compilation of data from MIR, Skylab and ISS on restraints, and investigating possibility of an in-flight evaluation of current restraint systems. Preliminary restraint concepts were developed and presented to long duration crewmembers and focus groups for feedback. Currently, a selection criterion is being refined for prioritizing the candidate concepts. Next steps include analytical and computer modeling evaluations of the selected candidate concepts, prototype development, and microgravity evaluations.

Whitmore, Mihriban↗

NASA NTRS2011

The Atacama Cosmology Telescope: Extragalactic Sources at 148 GHz in the 2008 Survey

We report on extragalactic sources detected in a 455 square-degree map of the southern sky made with data at a frequency of 148 GHz from the Atacama Cosmology Telescope 2008 observing season. We provide a catalog of 157 sources with flux densities spanning two orders of magnitude: from 15 mJy to 1500 mJy. Comparison to other catalogs shows that 98% of the ACT detections correspond to sources detected at lower radio frequencies. Three of the sources appear to be associated with the brightest cluster galaxies of low redshift X-ray selected galaxy clusters. Estimates of the radio to mm-wave spectral indices and differential counts of the sources further bolster the hypothesis that they are nearly all radio sources, and that their emission is not dominated by re-emission from warm dust. In a bright (> 50 mJy) 148 GHz-selected sample with complete cross-identifications from the Australia Telescope 20 GHz survey, we observe an average steepening of the spectra between .5, 20, and 148 GHz with median spectral indices of alp[ha (sub 5-20) = -0.07 +/- 0.06, alpha (sub 20-148) -0.39 +/- 0.04, and alpha (sub 5-148) = -0.20 +/- 0.03. When the measured spectral indices are taken into account, the 148 GHz differential source counts are consistent with previous measurements at 30 GHz in the context of a source count model dominated by radio sources. Extrapolating with an appropriately rescaled model for the radio source counts, the Poisson contribution to the spatial power spectrum from synchrotron-dominated sources with flux density less than 20 mJy is C(sup Sync) = (2.8 +/- 0.3) x 1O (exp-6) micro K(exp 2).

Marriage, T. A.↗

DOE OSTI2023

New Tables for Infrasound Event Catalogs with a Focus on Machine Learning

Natural and anthropogenic sources such as volcanoes, earthquakes, auroral processes, chemical and nuclear explosions, rocket launches, and aircraft can generate infrasound, sound with frequencies less than 20 Hz. Both the availability of infrasound data and interest in machine learning (ML) applications have grown in recent years. Large, open-source datasets are essential to solving complex ML problems, but the field of infrasound is lacking in this arena. To increase the utility of ML for infrasound, here we present new tables for infrasound event catalogs. It is the aim that these tables be incorporated into both existing and future infrasound processing pipelines to generate large datasets ripe for use with ML/DL methods.

47 OTHER INSTRUMENTATION↗

DOE OSTI2024

Measuring the Conditional Luminosity and Stellar Mass Functions of Galaxies by Combining the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys Data Release 9, Survey Validation 3, and Year 1 Data

In this investigation, we leverage the combination of the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys Data Release 9, Survey Validation 3, and Year 1 data sets to estimate the conditional luminosity functions and conditional stellar mass functions (CLFs and CSMFs) of galaxies across various halo mass bins and redshift ranges. To support our analysis, we utilize a realistic DESI mock galaxy redshift survey (MGRS) generated from a high-resolution Jiutian simulation. An extended halo-based group finder is applied to both MGRS catalogs and DESI observation. By comparing the r- and z-band luminosity functions (LFs) and stellar mass functions (SMFs) derived using both photometric and spectroscopic data, we quantified the impact of photometric redshift (photo-z) errors on the galaxy LFs and SMFs, especially in the low-redshift bin at the low-luminosity/mass end. By conducting prior evaluations of the group finder using MGRS, we successfully obtain a set of CLF and CSMF measurements from observational data. We find that at low redshift, the faint-end slopes of CLFs and CSMFs below ~10 9 h –2 L ⊙ (or h –2 M ⊙ ) evince a compelling concordance with the subhalo mass functions. After correcting the cosmic variance effect of our local Universe following Chen et al., the faint-end slopes of the LFs/SMFs turn out to also be in good agreement with the slope of the halo mass function.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2022

Classifying Unidentified X-Ray Sources in the Chandra Source Catalog Using A Multiwavelength Machine-Learning Approach

The rapid increase in serendipitous X-ray source detections requires the development of novel approaches to efficiently explore the nature of X-ray sources. If even a fraction of these sources could be reliably classified, it would enable population studies for various astrophysical source types on a much larger scale than currently possible. Classification of large numbers of sources from multiple classes characterized by multiple properties (features) must be done automatically and supervised machine learning (ML) seems to provide the only feasible approach. We perform classification of Chandra Source Catalog version 2.0 (CSCv2) sources to explore the potential of the ML approach and identify various biases, limitations, and bottlenecks that present themselves in these kinds of studies. We establish the framework and present a flexible and expandable Python pipeline, which can be used and improved by others. We also release the training data set of 2941 X-ray sources with confidently established classes. In addition to providing probabilistic classifications of 66,369 CSCv2 sources (21% of the entire CSCv2 catalog), we perform several narrower-focused case studies (high-mass X-ray binary candidates and X-ray sources within the extent of the H.E.S.S. TeV sources) to demonstrate some possible applications of our ML approach. We also discuss future possible modifications of the presented pipeline, which are expected to lead to substantial improvements in classification confidences.

Hui Yang↗

DOE OSTI2023

The Target-selection Pipeline for the Dark Energy Spectroscopic Instrument

Abstract In 2021 May, the Dark Energy Spectroscopic Instrument (DESI) began a 5 yr survey of approximately 50 million total extragalactic and Galactic targets. The primary DESI dark-time targets are emission line galaxies, luminous red galaxies, and quasars. In bright time, DESI will focus on two surveys known as the Bright Galaxy Survey and the Milky Way Survey. DESI also observes a selection of “secondary” targets for bespoke science goals. This paper gives an overview of the publicly available pipeline ( desitarget ) used to process targets for DESI observations. Highlights include details of the different DESI survey targeting phases, the targeting ID ( TARGETID ) used to define unique targets, the bitmasks used to indicate a particular type of target, the data model and structure of DESI targeting files, and examples of how to access and use the desitarget code base. This paper will also describe “supporting” DESI target classes, such as standard stars, sky locations, and random catalogs that mimic the angular selection function of DESI targets. The DESI target-selection pipeline is complex and sizable; this paper attempts to summarize the most salient information required to understand and work with DESI targeting data.

47 OTHER INSTRUMENTATION↗

NASA NTRS1987

A very deep IRAS survey at the north ecliptic pole

The data from approximately 20 hours observation of the 4- to 6-square degree field surrounding the north ecliptic pole have been combined to produce a very deep IR survey at the four IRAS bands. Scans from both pointed and survey observations were included in the data analysis. At 12 and 25 microns the deep survey is limited by detector noise and is approximately 50 times deeper than the IRAS Point Source Catalog (PSC). At 60 microns the problems of source confusion and Galactic cirrus combine to limit the deep survey to approximately 12 times deeper than the PSC. These problems are so severe at 100 microns that flux values are only given for locations corresponding to sources selected at 60 microns. In all, 47 sources were detected at 12 microns, 37 at 25 microns, and 99 at 60 microns. The data-analysis procedures and the significance of the 12- and 60-micron source-count results are discussed.

Houck, J. R.↗

NASA NTRS2004

NASA's Swarm Missions: The Challenge of Building Autonomous Software

The days of watching a massive manned cylinder thrust spectacularly off a platform into space might rapidly become ancient history when the National Aeronautics and Space Administration (NASA) introduces its new millenium mission class. Motivated by the need to gather more data than is possible with a single spacecraft, scientists have developed a new class of missions based on the efficiency and cooperative nature of a hive culture. The missions, aptly dubbed nanoswarm will be little more than mechanized colonies cooperating in their exploration of the solar system. Each swarm mission can have hundreds or even thousands of cooperating intelligent spacecraft that work in teams. The spacecraft must operate independently for long periods both in teams and individually, as well as have autonomic properties - self-healing, -configuring, -optimizing, and -protecting- to survive the harsh space environment. One swarm mission under concept development for 2020 to 2030 is the Autonomous Nano Technology Swarm (ANTS), in which a thousand picospacecraft, each weighing less than three pounds, will work cooperatively to explore the asteroid belt. Some spacecraft will form teams to catalog asteroid properties, such as mass, density, morphology, and chemical composition, using their respective miniature scientific instruments. Others will communicate with the data gatherers and send updates to mission elements on Earth. For software and systems development, this is uncharted territory that calls for revolutionary techniques.

Truszkowski, Walt↗

DOE OSTI2021

Protocols for Uranium Carbon Analysis

In 1998, MST-6 (now SIGMA) installed a Horiba EMIA-8200 Carbon/Sulfur analyzer to provide the ability to perform in-house chemical analysis on a variety of materials including uranium. While many of the results and procedures were detailed in program files, no compiled record of the overall analytic process was ever published. This retrospective utilizes existing logbooks, operator interviews, instrument manuals, and notes to catalog what is known about the past procedures and protocols for carbon analysis that were established and present the data informing those decisions.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2021

Seeking Echoes of Circumstellar Disks in Kepler Light Curves

Light echoes of flares on active stars offer the opportunity for direct detection of circumstellar dust. We revisit the problem of identifying faint echoes in postflare light curves, focusing on debris disks from ongoing planet formation. Starting with simulations, we develop an algorithm for estimating the radial extent and total mass from disk echo profiles. We apply this algorithm to light curves from over 2100 stars observed by NASA’s Kepler mission, selected for multiple short-lived flares in either the long-cadence or short-cadence data sets. While flux uncertainties in light curves from individual stars preclude useful mass limits on circumstellar disks, catalog-averaged light curves yield constraints on disk mass that are comparable to estimates from known debris disks. The average mass in micron- to millimeter-sized dust around the Kepler stars cannot exceed 10% of an Earth mass in exo-Kuiper belts or 10% of a lunar mass in the terrestrial zone. We group stars according to IR excess, based on WISE W1–W3 color, as an indicator for the presence of circumstellar dust. The mass limits are greater for stars with strong IR excess, a hint that echoes are lurking not far beneath the noise in postflare light curves. With increased sensitivity, echo detection will let time-domain astronomy complement spectroscopic and direct-imaging studies in mapping how, when, and where planets form.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1976

LANDSAT: US standard catalog, 1-29 February 1976

The U.S. Standard Catalog lists U.S. imagery acquired by LANDSAT 1 and LANDSAT 2 which has been processed and input to the data files during the referenced month. Data, such as date acquired, cloud cover and image quality are given for each scene. The microfilm roll and frame on which the scene may be found is also given.

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NASA NTRS1976

LANDSAT US standard catalog, 1-31 March 1976

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NASA NTRS1976

LANDSAT US standard catalog, 1-31 May 1976

The U.S. standard catalog lists U.S. imagery acquired by LANDSAT 1 and LANDSAT 2 which has been processed and input to the data files during the referenced month. Data, such as date acquired, cloud cover and image quality are given for each scene. The microfilm and frame on which the scene may be found is also given.

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NASA NTRS1976

LANDSAT 1 non-US cumulative catalog, 1975 - 1976

The LANDSAT 1 non-U.S. Cumulative Catalog lists Non-U.S. imagery acquired by LANDSAT 1 which has been processed and input to the data files during the referenced year. Data, such as date acquired, cloud cover and image quality are given for each scene. The microfilm roll and frame on which the scene may be found is also given.

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NASA NTRS1976

LANDSAT US standard catalog, 1-30 November 1976

The U.S. Standard Catalog lists U.S. imagery acquired by LANDSAT 1 and LANDSAT 2 which las been processed and input to the data files during the referenced month. Data, such as date acquired, cloud cover and image quality are given for each scene. The microfilm roll and frame on which the scene may be found is also given.

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NASA NTRS1976

LANDSAT: US Standard Catalog, 1-31 December 1976

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NASA NTRS1977

LANDSAT: US standard catalog, 1 January 1977 through 31 January 1977

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NASA NTRS1977

LANDSAT: US standard catalog, 1 February 1977 - 28 February 1977

The U.S. Standard Catalog lists U.S. imagery acquired by LANDSAT 1 and LANDSAT 2 which has been processed and input to the data files during the referenced month. Data, such as data acquired, cloud cover and image quality are given for each scene. The microfilm roll and frame on which the scene may be found is also given.

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