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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

An Update to the NASA Reference Solar Sail Thrust Model

An optical model of solar sail material originally derived at JPL in 1978 has since served as the de facto standard for NASA and other solar sail researchers. The optical model includes terms for specular and diffuse reflection, thermal emission, and non-Lambertian diffuse reflection. The standard coefficients for these terms are based on tests of 2.5 micrometer Kapton sail material coated with 100 nm of aluminum on the front side and chromium on the back side. The original derivation of these coefficients was documented in an internal JPL technical memorandum that is no longer available. Additionally more recent optical testing has taken place and different materials have been used or are under consideration by various researchers for solar sails. Here, where possible, we re-derive the optical coefficients from the 1978 model and update them to accommodate newer test results and sail material. The source of the commonly used value for the front side non-Lambertian coefficient is not clear, so we investigate that coefficient in detail. Although this research is primarily designed to support the upcoming NASA NEA Scout and Lunar Flashlight solar sail missions, the results are also of interest to the wider solar sail community.

Heaton, Andrew F.↗
NASA NTRS2015

Emerging US Space Launch, Trends and Space Solar Power

Reviews the state of the art of emerging US space launch and spacecraft. Reviews the NASA budget ascontext, while providing example scenarios. Connects what has been learned in space systems commercial partnershipsto a potential path for consideration by the space solar power community.

space solor power↗
NASA NTRS2005

Photovoltaic Engineering

The Ohio Aerospace Institute through David Scheiman and Phillip Jenkins provided the Photovoltaics Branch at the NASA Glenn Research Center (GRC) with expertise in photovoltaic (PV) research, flight experiments and solar cell calibration. NASA GRC maintains the only world-class solar cell calibration and measurement facility within NASA. GRC also has a leadership role within the solar cell calibration community, and is leading the effort to develop ISO standards for solar cell calibration. OAI scientists working under this grant provided much of the expertise and leadership in this area.

Source record↗
NASA NTRS2013

The Solar Umbrella: A Low-cost Demonstration of Scalable Space Based Solar Power

Within the past decade, the Space Solar Power (SSP) community has seen an influx of stakeholders willing to entertain the SSP prospect of potentially boundless, base-load solar energy. Interested parties affiliated with the Department of Defense (DoD), the private sector, and various international entities have all agreed that while the benefits of SSP are tremendous and potentially profitable, the risk associated with developing an efficient end to end SSP harvesting system is still very high. In an effort to reduce the implementation risk for future SSP architectures, this study proposes a system level design that is both low-cost and seeks to demonstrate the furthest transmission of wireless power to date. The overall concept is presented and each subsystem is explained in detail with best estimates of current implementable technologies. Basic cost models were constructed based on input from JPL subject matter experts and assume that the technology demonstration would be carried out by a federally funded entity. The main thrust of the architecture is to demonstrate that a usable amount of solar power can be safely and reliably transmitted from space to the Earth's surface; however, maximum power scalability limits and their cost implications are discussed.

climate change↗
NASA NTRS2004

Design Considerations for an Integrated Solar Sail Diagnostics System

Efforts are continuing under NASA support to improve the readiness level of solar sail technology. Solar sails have one of the best chances to be the next gossamer spacecraft flown in space. In the gossamer spacecraft community thus far, solar sails have always been considered a "low precision" application compared with, say, radar or optical devices. However, as this paper shows, even low precision gossamer applications put extraordinary demands on structural measurement systems if they are to be traceable to use in space.

Jenkins, Christopher H. M.↗
NASA NTRS2011

SCOSTEP: Understanding the Climate and Weather of the Sun-Earth System

The international solar-terrestrial physics community had recognized the importance of space weather more than a decade ago, which resulted in a number of international collaborative activities such as the Climate and Weather of the Sun Earth System (CAWSES) by the Scientific Committee on Solar Terrestrial Physics (SCOSTEP). The CAWSES program is the current major scientific program of SCOSTEP that will continue until the end of the year 2013. The CAWSES program has brought scientists from all over the world together to tackle the scientific issues behind the Sun-Earth connected system and explore ways of helping the human society. In addition to the vast array of space instruments, ground based instruments have been deployed, which not only filled voids in data coverage, but also inducted young scientists from developing countries into the scientific community. This paper presents a summary of CAWSES and other SCOSTEP activities that promote space weather science via complementary approaches in international scientific collaborations, capacity building, and public outreach.

Gopalswamy, Natchimuthuk↗
NASA NTRS1996

Contamination control engineering design guidelines for the aerospace community

Thermal control surfaces, solar arrays, and optical devices may be adversely affected by a small quantity of molecular and/or particulate contamination. What is rarely discussed is how one: (1) quantifies the level of contamination that must be maintained in order for the system to function properly, and (2) enforces contamination control to ensure compliance with requirements. This document is designed to address these specific issues and is intended to serve as a handbook on contamination control for the reader, illustrating process and methodology while providing direction to more detailed references when needed. The effects of molecular contamination on reflecting and transmitting surfaces are examined and quantified in accordance with MIL STD 1246C. The generation, transportation, and deposition of molecular contamination is reviewed and specific examples are worked to illustrate the process a design engineer can use to estimate end of life cleanliness levels required by solar arrays, thermal control surfaces, and optical surfaces. A similar process is used to describe the effect of particulate contamination as related to percent area coverage (PAC) and bi-directional reflectance distribution function (BRDF). Relationships between PAC and surface cleanliness, which include the effects of submicron sized particles, are developed and BRDF is related to specific sensor design parameters such as Point Source Transmittance (PST). The pros and cons of various methods of preventing, monitoring, and cleaning surfaces are examined and discussed.

Tribble, A. C.↗
NASA NTRS2011

Solar System Planetary Science Decadal Survey and Missions in the Next Decade, 2013-2022

In 2010, the National Research Council Space Studies Board established a decadal survey committee to develop a comprehensive science, mission, and technology strategy for planetary science that updates and extends the Board's 2003 Solar System Exploration Decadal Survey, "New Frontiers in the Solar System: An Integrated Exploration Strategy." The scope of the survey encompasses the inner planets (Mercury, Venus, and Mars), the Earth's Moon, the giant planets (Jupiter, Saturn, Uranus, and Neptune), the moons of the giant planets, dwarf planets and small bodies, primitive bodies including comets and Kuiper Belt objects, and astrobiology. Over this past year, the decadal survey committee has interacted with the broad solar system science community to determine the current state of knowledge and to identify the most important scientific questions expected to face the community during the interval 2013-2022. The survey has identified candidate missions that address the most important science questions and has conducted, through NASA sponsorship, concept studies to assess the cost of such missions as well as technology needs. The purpose of this paper is to provide an overview of the 2012 Solar System Planetary Science Decadal Survey study approach and missions that were studied for implementation in the upcoming decade. Final results of the decadal survey, including studies that were completed and the specific science, programmatic, and technology recommendations will be disclosed publically in the spring of 2011 and are not the subject of this paper.

Reh, Kim↗
NASA NTRS2008

Ares V and Future Very Large Launch Vehicles to Enable Major Astronomical Missions

The current NASA architecture planned to return humans to the lunar surface includes the Ares V heavy lift launch vehicle designed primarily to carry the Altair lunar lander and to be available before about 2020. However. the capabilities of this system (and its variants) are such that adapting the vehicle to launch very large optical systems could achieve major scientific goals that are not otherwise possible. For example, an 8-m monolith UV/visual/IR telescope appears able to be launched to the Sun-Earth L2 location by an Ares V with a 10-m fairing. Even larger apertures that are deployed or assembled in space seem possible, which may take advantage of other elements of NASA's future human spaceflight architecture. Alternatively. multiple elements of a spatial array or two or three astronomical observatories might he launched simultaneously. That is, Ares V appears to offer the astronomy communities an opportunity to put into orbit extremely capable observatories, in addition to being a key element of NASA's current architecture for human spaceflight. For the past year, a number of scientists and engineers have been eva1uating concepts for astronomical observatories that take advantage of future large launch vehicles, including the science goals of such missions and design modifications to the vehicle to enable the observatories. In parallel, members of the Solar System science communities have likewise been considering what major science goals can be achieved if new, extremely capable launch systems become available.

Thronson, Harley↗
NASA NTRS1999

The Observed Spectral Evolution of Solar Flare Hard X-Ray Emission

The spectral evolution of flare emission may be characterized using color-color diagrams (CCDs), a technique which has been widely employed by the astrophysics community, but not yet by the solar flare community. CCDs are constructed for a sample of flares observed simultaneously by CGRO/BATSE and Yohkoh/HXT. It is found that flare spectral evolution follows one of only a few patterns, which generally evolve differently than the soft-hard-soft pattern put forth as the norm in previous work. The implications for the nature of flare energy release and acceleration/propagation models are discussed

Newton, Elizabeth↗
NASA NTRS2016

Validation for Global Solar Wind Prediction Using Ulysses Comparison: Multiple Coronal and Heliospheric Models Installed at the Community Coordinated Modeling Center

The prediction of the background global solar wind is a necessary part of space weather forecasting. Several coronal and heliospheric models have been installed and/or recently upgraded at the Community Coordinated Modeling Center (CCMC), including the Wang-Sheely-Arge (WSA)-Enlil model, MHD-Around-a-Sphere (MAS)-Enlil model, Space Weather Modeling Framework (SWMF), and Heliospheric tomography using interplanetary scintillation data. Ulysses recorded the last fast latitudinal scan from southern to northern poles in 2007. By comparing the modeling results with Ulysses observations over seven Carrington rotations, we have extended our third-party validation from the previous near-Earth solar wind to middle to high latitudes, in the same late declining phase of solar cycle 23. Besides visual comparison, wehave quantitatively assessed the models capabilities in reproducing the time series, statistics, and latitudinal variations of solar wind parameters for a specific range of model parameter settings, inputs, and grid configurations available at CCMC. The WSA-Enlil model results vary with three different magnetogram inputs.The MAS-Enlil model captures the solar wind parameters well, despite its underestimation of the speed at middle to high latitudes. The new version of SWMF misses many solar wind variations probably because it uses lower grid resolution than other models. The interplanetary scintillation-tomography cannot capture the latitudinal variations of solar wind well yet. Because the model performance varies with parameter settings which are optimized for different epochs or flow states, the performance metric study provided here can serve as a template that researchers can use to validate the models for the time periods and conditions of interest to them.

Jian, L. K.↗
NASA NTRS1997

An overview of IACG campaign 4: Solar sources of heliospheric structure observed out of the ecliptic

In 1994, the Inter Agency Consultative Group (IACG), with represenation from ESA, the Japanese Institute of Space and Astronautical Science, the Russian Space Agency, and NASA, initiated a data analysis campaign entitled: 'solar sources of heliospheric structure observed out of the ecliptic' (IACG campaign 4). The primary campaign themes are: the large-scale heliosphere and its dependence on solar photospheric and coronal phenomena; the topology of coronal streamers; the 3D shape of coronal hole boundaries, and solar wind source and acceleration. These themes emphasize the collaborative analysis of remote sensing and in situ data sets for solar features such as coronal holes, coronal mass ejections, and other other solar sources of heliospheric structure. The key observation intervals, covering June 1994 to January 1997, were selected based on the timeline of the unique trajectory of the Ulysses mission. The capabilities and opportunities afforded by the core campaing missions, Ulysses and Yohkoh, and the availability of supportin solar ground observatories and other spacecraft missions, make this campaign of special interest to the solar and heliospheric communities.

Galvin, A. B.↗
NASA NTRS2009

Initial Results of Aperture Area Comparisons for Exo-Atmospheric Total Solar Irradiance Measurements

In the measurement of exo-atmospheric total solar irradiance (TSI), instrument aperture area is a critical component in converting solar radiant flux to irradiance. In a May 2000 calibration workshop for the Total Irradiance Monitor (TIM) on the Earth Observing System (EOS) Solar Radiation and Climate Experiment (SORCE), the solar irradiance measurement community recommended that NASA and NISI coordinate an aperture area measurement comparison to quantify and validate aperture area uncertainties and their overall effect on TSI uncertainties. From May 2003 to February 2006, apertures from 4 institutions with links to the historical TSI database were measured by NIST and the results were compared to the aperture area determined by each institution. The initial results of these comparisons are presented and preliminary assessments of the participants' uncertainties are discussed.

Johnson, B. Carol↗
NASA NTRS2011

Accurate Radiometry from Space: An Essential Tool for Climate Studies

The Earth s climate is undoubtedly changing; however, the time scale, consequences and causal attribution remain the subject of significant debate and uncertainty. Detection of subtle indicators from a background of natural variability requires measurements over a time base of decades. This places severe demands on the instrumentation used, requiring measurements of sufficient accuracy and sensitivity that can allow reliable judgements to be made decades apart. The International System of Units (SI) and the network of National Metrology Institutes were developed to address such requirements. However, ensuring and maintaining SI traceability of sufficient accuracy in instruments orbiting the Earth presents a significant new challenge to the metrology community. This paper highlights some key measurands and applications driving the uncertainty demand of the climate community in the solar reflective domain, e.g. solar irradiances and reflectances/radiances of the Earth. It discusses how meeting these uncertainties facilitate significant improvement in the forecasting abilities of climate models. After discussing the current state of the art, it describes a new satellite mission, called TRUTHS, which enables, for the first time, high-accuracy SI traceability to be established in orbit. The direct use of a primary standard and replication of the terrestrial traceability chain extends the SI into space, in effect realizing a metrology laboratory in space . Keywords: climate change; Earth observation; satellites; radiometry; solar irradiance

Fox, Nigel↗
NASA NTRS2023

Data Mining for Science of the Sun-Earth Connection as a Single System

Establishing the Sun-Earth connection requires overcoming the challenges of exploring the data from past and current missions and leveraging tools and models (data mining) to create an efficient system treatment of the Sun and heliosphere. However, solar and heliospheric environment data constitute a vast source of information whose potential is far from being optimally exploited. In the next decade, the solar and heliospheric community will have to manage the increasing amount of information coming from new missions, improve reanalysis of data from past and current missions, and create new data products from the application of new methodologies. This complex task is further complicated by practical challenges such as different datasets and catalogs in different formats that may require different pre-processing and analysis tools, and the need for numerous analysis approaches that are not all fully optimized for large volumes of data. While several ongoing efforts aim at addressing these problems, the available datasets and tools are not always used to their full potential often due to lack of awareness of available resources. In this paper, we summarize the issues raised and goals discussed by members of the community during recent conference sessions focused on data mining for science.

Sun-Earth connection↗
NASA NTRS2023

The SunPy Project: An Interoperable Ecosystem for Solar Data Analysis

The SunPy Project is a community of scientists and software developers creating an ecosystem of Python packages for solar physics. The project includes the sunpy core package as well as a set of affiliated packages. The sunpy core package provides general purpose tools to access data from different providers, read image and time series data, and transform between commonly used coordinate systems. Affiliated packages perform more specialized tasks that do not fall within the more general scope of the sunpy core package. In this article, we give a high-level overview of the SunPy Project, how it is broader than the sunpy core package, and how the project curates and fosters the affiliated package system. We demonstrate how components of the SunPy ecosystem, including sunpy and several affiliated packages, work together to enable multi-instrument data analysis workflows. We also describe members of the SunPy Project and how the project interacts with the wider solar physics and scientific Python communities. Finally, we discuss the future direction and priorities of the SunPy Project.

Solar physics↗
NASA NTRS2011

Spectral Analyses and Radiation Exposures from Several Ground-Level Enhancement (GLE) Solar Proton Events: A Comparison of Methodologies

Several methods for analyzing the particle spectra from extremely large solar proton events, called Ground-Level Enhancements (GLEs), have been developed and utilized by the scientific community to describe the solar proton energy spectra and have been further applied to ascertain the radiation exposures to humans and radio-sensitive systems, namely electronics. In this paper 12 GLEs dating back to 1956 are discussed, and the three methods for describing the solar proton energy spectra are reviewed. The three spectral fitting methodologies are EXP [an exponential in proton rigidity (R)], WEIB [Weibull fit: an exponential in proton energy], and the Band function (BAND) [a double power law in proton rigidity]. The EXP and WEIB methods use low energy (MeV) GLE solar proton data and make extrapolations out to approx.1 GeV. On the other hand, the BAND method utilizes low- and medium-energy satellite solar proton data combined with high-energy solar proton data deduced from high-latitude neutron monitoring stations. Thus, the BAND method completely describes the entire proton energy spectrum based on actual solar proton observations out to ~10 GeV. Using the differential spectra produced from each of the 12 selected GLEs for each of the three methods, radiation exposures are presented and discussed in detail. These radiation exposures are then compared with the current 30-day and annual crew exposure limits and the radiation effects to electronics.

Atwell, William↗
NASA NTRS2018

Solar System Science with the Wide-Field Infrared Survey Telescope

We present a community-led assessment of the solar system investigations achievable with NASA's next-generation space telescope, the Wide Field Infrared Survey Telescope (WFIRST). WFIRST will provide imaging, spectroscopic, and coronagraphic capabilities from 0.43 to 2.0 m and will be a potential contemporary and eventual successor to the James Webb Space Telescope (JWST). Surveys of irregular satellites and minor bodies are where WFIRST will excel with its 0.28 deg2 field-of-view Wide Field Instrument. Potential ground- breaking discoveries from WFIRST could include detection of the first minor bodies orbiting in the inner Oort Cloud, identification of additional Earth Trojan asteroids, and the discovery and characterization of asteroid binary systems similar to Ida/Dactyl. Additional investigations into asteroids, giant planet satellites, Trojan asteroids, Centaurs, Kuiper belt objects, and comets are presented. Previous use of astrophysics assets for solar system science and synergies between WFIRST, Large Synoptic Survey Telescope, JWST, and the proposed Near-Earth Object Camera mission is discussed. We also present the case for implementation of moving target tracking, a feature that will benefit from the heritage of JWST and enable a broader range of solar system observations.

Holler, Bryan J.↗