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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 973 records · Page 54

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NASA NTRS2007

IMP 8 GME Particle Observations Over Three Solar Cycles

The Goddard Medium Energy experiment on the IMP 8 spacecraft has made nearly continuous observations of the near-Earth energetic particle environment from its launch in October, 1973 until near present. We summarize several aspects of these observations, including solar energetic particle events, CIR-associated events, and cosmic ray modulations. In particular, we note that, as expected fiom the pattern of smaller recurrent (27 day) cosmic ray modulations seen in the mid 1980's A less than 0 solar minimum compared to the previous and following (A greater than 0) minima, recurrent modulations are again reduced in the current solar minimum.

Richardson, Ian↗

NASA NTRS1975

The X-ray line and continuum emission from a solar active region

The X-ray spectrum of the quiet sun in the energy range of 2.3-6.9 keV was observed from an Aerobee rocket using an uncollimated graphite crystal spectrometer. These results and spatial measurements made with an onboard modulation collimator are analyzed using solar models. Several methods of estimating coronal temperatures are used in the analysis and all yield results within the range of (4 plus or minus 1) million K.

Landecker, P. B.↗

NASA NTRS1978

The solar power satellite concept evaluation program

The paper describes in detail one of the preliminary baseline concepts for the solar power satellite (SPS). A large space freighter with payload capacity of 424 metric tons will deliver the material to a construction base in low earth orbit where the eight modules of the satellite are constructed. Electric thrusters will propel the modules to a smaller geosynchronous base, where the modules are docked and the solar arrays are deployed to form a satellite capable of providing 5 GW power from each of two end-mounted antennas to the two ground rectennas. The solar array is 5.3 km by 21.3 km to provide a total platform area of 113 sq km. The solar array employs silicon solar cells with a concentration ratio of unity. Details on transportation, construction bases, rectenna, and solar array design are given along with material requirements and cost estimates.

Piland, R. O.↗

NASA NTRS2006

Analyzing Power Supply and Demand on the ISS

Station Power and Energy Evaluation Determiner (SPEED) is a Java application program for analyzing the supply and demand aspects of the electrical power system of the International Space Station (ISS). SPEED can be executed on any computer that supports version 1.4 or a subsequent version of the Java Runtime Environment. SPEED includes an analysis module, denoted the Simplified Battery Solar Array Model, which is a simplified engineering model of the ISS primary power system. This simplified model makes it possible to perform analyses quickly. SPEED also includes a user-friendly graphical-interface module, an input file system, a parameter-configuration module, an analysis-configuration-management subsystem, and an output subsystem. SPEED responds to input information on trajectory, shadowing, attitude, and pointing in either a state-of-charge mode or a power-availability mode. In the state-of-charge mode, SPEED calculates battery state-of-charge profiles, given a time-varying power-load profile. In the power-availability mode, SPEED determines the time-varying total available solar array and/or battery power output, given a minimum allowable battery state of charge.

Thomas, Justin↗

NASA NTRS2009

Phytoplankton and Climate

Ocean phytoplankton supply about half of the oxygen that humans utilize to sustain life. In this lecture, we will explore how phytoplankton plays a critical role in modulating the Earth's climate. These tiny organisms are the base of the Ocean's food web. They can modulate the rate at which solar heat is absorbed by the ocean, either through direct absorption or through production of highly scattering cellular coverings. They take up and help sequester carbon dioxide, a key greenhouse gas that modulated the Earth's climate. They are the source of cloud nucleation gases that are key to cloud formation/processes. They are also able to modify the nutrient budgets of the ocean through active uptake of inert atmospheric nitrogen. Climate variations have a pronounced impact on phytoplankton dynamics. Long term variations in the climate have been studied through geological interpretations on its influence on phytoplankton populations. The presentation will focus on presenting the numerous linkages that have been observed between climate and phytoplankton and further discuss how present climate change scenarios are likely to impact phytoplankton populations as well as present findings from several studies that have tried to understand how the climate might react to the feedbacks from these numerous climate-phytop|ankton linkages.

Moisan, John R.↗

NASA NTRS1991

Latitudinal dynamics of steady solar wind flows

In many previous studies, it has been assumed that the streamlines of the solar wind are in a purely radial direction beyond a few solar radii. Therefore, the nonradial modulations by the magnetic force and gas pressure is neglected at large heliocentric distances. The work reported in this paper includes a two-dimensional magnetohydrodynamic (MHD) study of the latitudinal structure of solar wind flows. The dynamical effects of the interplanetary magnetic field (IMF) are investigated by MHD solutions and by comparing them with both one-dimensional and two-dimensional hydrodynamic (HD) solutions. The corotational effect of the sun and the influence of transient events in the solar atmosphere are neglected. With such a simplification, the latitudinal structure of the steady solar wind is controlled by the dynamic balance of the magnetic force and the gas pressure. Several different patterns of the evolution of the solar wind latitudinal structure are exhibited in the calculation. The results indicate the existence of a proton number density maximum at the magnetic neutral line, whether or not there is a density maximum or minimum at the inner boundary. The drift motion of magnetic field lines toward the magnetic neutral line enhances the magnetic field strength around the neutral sheet, which may provide a possible explanation of the discrepancy between the measured IMF at 1 AU and that extrapolated from the photospheric magnetic field by the current source-surface modeling.

Yang, W.-H.↗

NASA NTRS2012

Lunar Crater Mini-Wakes: Structure, Variability, and Volatiles

Within a permanently shadowed lunar crater the horizontal flow of solar wind is obstructed by upstream topography, forming a regional plasma mini-wake. In the present work kinetic simulations are utilized to investigate how the most prominent structural aspects of a crater mini-wake are modulated during passage of a solar storm. In addition, the simulated particle fluxes are coupled into an equivalent-circuit model of a roving astronaut,. including triboelectric charging due to frictional contact with the lunar regolith, to characterize charging of the astronaut suit during the various stages of the storm. In some cases, triboelectric charging of the astronaut suit becomes effectively perpetual, representing a critical engineering concern for roving within shadowed lunar regions. Finally, the present results suggest that wake structure plays a critical role in modulating the spatial distribution of volatiles at the lunar poles.

Zimmerman, Michael I.↗

NASA NTRS2013

Improvements of VIIRS and MODIS Solar Diffuser and Lunar Calibration

Both VIIRS and MODIS instruments use solar diffuser (SD) and lunar observations to calibrate their reflective solar bands (RSB). A solar diffuser stability monitor (SDSM) is used to track the SD on-orbit degradation. On-orbit observations have shown similar wavelength-dependent SD degradation (larger at shorter VIS wavelengths) and SDSM detector response degradation (larger at longer NIR wavelengths) for both VIIRS and MODIS instruments. In general, the MODIS scan mirror has experienced more degradation in the VIS spectral region whereas the VIIRS rotating telescope assembly (RTA) mirrors have seen more degradation in the NIR and SWIR spectral region. Because of this wavelength dependent mirror degradation, the sensor's relative spectral response (RSR) needs to be modulated. Due to differences between the solar and lunar spectral irradiance, the modulated RSR could have different effects on the SD and lunar calibration. In this paper, we identify various factors that should be considered for the improvements of VIIRS and MODIS solar and lunar calibration and examine their potential impact. Specifically, we will characterize and assess the calibration impact due to SD and SDSM attenuation screen transmission (uncertainty), SD BRF uncertainty and onorbit degradation, SDSM detector response degradation, and modulated RSR resulting from the sensor's optics degradation. Also illustrated and discussed in this paper are the calibration strategies implemented in the VIIRS and MODIS SD and lunar calibrations and efforts that could be made for future improvements.

VIIRS↗

NASA NTRS1974

Test report SEPS solar array root section model

The fabrication and test of a solar array functional root section model to verify preliminary array design concepts is presented. The root section model is full scale width and contains a model array blanket. The blanket contains 1/8 live electrical modules and the remainder contains solar cell mass simulators. A storable Astromast is used for array blanket extension and retraction. The model component and system assembly hardware, tests, and test results are described.

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NASA NTRS1981

Alkaline regenerative fuel cell systems for energy storage

A description is presented of the results of a preliminary design study of a regenerative fuel cell energy storage system for application to future low-earth orbit space missions. The high energy density storage system is based on state-of-the-art alkaline electrolyte cell technology and incorporates dedicated fuel cell and electrolysis cell modules. In addition to providing energy storage, the system can provide hydrogen and oxygen for attitude control of the satellite and for life support. During the daylight portion of the orbit the electrolysis module uses power provided by the solar array to generate H2 and O2 from the product water produced by the fuel cell module. The fuel cell module supplies electrical power during the dark period of the orbit.

Schubert, F. H.↗

NASA NTRS1991

Microprocessor control of multiple peak power tracking DC/DC converters for use with solar cell arrays

A method and an apparatus is provided for efficiently controlling the power output of a solar cell array string or a plurality of solar cell array strings to achieve a maximum amount of output power from the strings under varying conditions of use. Maximum power output from a solar array string is achieved through control of a pulse width modulated DC/DC buck converter which transfers power from a solar array to a load or battery bus. The input voltage from the solar array to the converter is controlled by a pulse width modulation duty cycle, which in turn is controlled by a differential signal controller. By periodically adjusting the control voltage up or down by a small amount and comparing the power on the load or bus with that generated at different voltage values a maximum power output voltage may be obtained. The system is totally modular and additional solar array strings may be added to the system simply by adding converter boards to the system and changing some constants in the controller's control routines.

Frederick, Martin E.↗

NASA NTRS2001

Thermal Analysis for Orbiter and ISS Plume Impingement on International Space Station

The NASA Reaction Control System (RCS) Plume Model (RPM) is an exhaust plume flow field and impingement heating code that has been updated and applied to components of the International Space Station (ISS). The objective of this study was to use this code to determine if plume environments from either Orbiter PRCS jets or ISS reboost and Attitude Control System (ACS) jets cause thermal issues on ISS component surfaces. This impingement analysis becomes increasingly important as the ISS is being assembled with its first permanent crew scheduled to arrive by the end of fall 2000. By early summer 2001 , the ISS will have a number of major components installed such as the Unity (Node 1), Destiny (Lab Module), Zarya (Functional Cargo Block), and Zvezda (Service Module) along with the P6 solar arrays and radiators and the Z-1 truss. Plume heating to these components has been analyzed with the RPM code as well as additional components for missions beyond Flight 6A such as the Propulsion Module (PM), Mobile Servicing System, Space Station Remote Manipulator System, Node 2, and the Cupola. For the past several years NASA/JSC has been developing the methodology to predict plume heating on ISS components. The RPM code is a modified source flow code with capabilities for scarfed nozzles and intersecting plumes that was developed for the 44 Orbiter RCS jets. This code has been validated by comparison with Shuttle Plume Impingement Flight Experiment (SPIFEX) heat flux and pressure data and with CFD and Method of Characteristics solutions. Previous analyses of plume heating predictions to the ISS using RPM have been reported, but did not consider thermal analysis for the components nor jet-firing histories as the Orbiter approaches the ISS docking ports. The RPM code has since been modified to analyze surface temperatures with a lumped mass approach and also uses jet-firing histories to produce pulsed heating rates. In addition, RPM was modified to include plume heating from ISS jets to ISS components where the jet coordinates are specified, together with the engine cant angle. These latter studies have been focused on the PM with plumes from its reboost and ACS jets impinging on various ISS components and also focused on the Japanese H2 Transfer Vehicle (HTV) with the plumes from its reboost engines impinging on the Cupola window. This paper will present plume heating and surface temperature results on a number of ISS components with and without jet-firing histories, evaluate post-flight data, and describe any potential thermal issues

Rochelle, William C.↗

NASA NTRS2023

Assembly of the FOXSI-4 Mirror Modules

The Focusing Optics X-ray Solar Imager 4 (FOXSI 4) is a heliophysics sounding rocket experiment that is currently in its fourth launch campaign. The payload is comprised of seven 2 m focal length X-ray telescopes, which each consist of a grazing incidence mirror module that focuses x-rays onto an imaging detector. For this fourth flight, Marshall Space Flight Center (MSFC) designed, built, and tested three new high-angular-resolution optics. This paper describes the design and assembly of the FOXSI 4 mirror modules.

Stephen D. Bongiorno↗

NASA NTRS2023

Assembly of the FOXSI-4 Mirror Modules

The Focusing Optics X-ray Solar Imager 4 (FOXSI-4) is a heliophysics sounding rocket experiment that is currently in its fourth launch campaign. The payload is comprised of seven x-ray telescopes, which each consist of a 2 m focal length grazing incidence mirror module that focuses x-rays onto an imaging detector. For this fourth flight, Marshall Space Flight Center (MSFC) designed, built, and tested three new high-angular-resolution mirror module assemblies (MMAs). This paper describes the design and assembly of the FOXSI-4 MMAs.

FOXSI-4↗

NASA NTRS1978

Passive heat exchanger for solar heating

Requirements for design, manufacture, installation, and performance of passive heat-exchanger module with auxiliary heaters for use with solar-heating systems are described.

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NASA NTRS1984

Repairing Solar Max: The Solar Maximum Repair Mission

Technology and procedures designed for replacing a faulty attitude control module and scientific instruments on the only orbiting solar observatory are described. The rationale for the repair mission is given and the operations of the flight support system within the cargo bay of the space shuttle are discussed. The use of the manned maneuvering unit in capturing the satellite and of the remote manipulator arm in berthing it are discussed, as well as the space tools to be used for repair operations. The space crew and their responsibilities are identified.

Mcmahan, T.↗

NASA NTRS1982

The OSS-1/STS-3 mission

Integration, test, flight operations, program and science management, and experiment results from the OSS-1/STS-3 flight are reviewed. The experimental pallet, manufactured by ESA members, carried instrumentation for astronomy, space plasma studies, physics, planetology, solar physics, and life sciences. The ability of the equipment to operate in a worst-case Orbiter thermal environment was tested, as was the plasma environment around the Orbiter. The solar UV spectral irradiance monitor microprocessor was found to reset concurrently with start-up of the Shuttle hydraulic pumps. Degradations were also observed in one of the three solar flare X ray polarimeter modules, the thermal cannister experiment microprocessor, and the scientific data recorder no. 2. The Orbiter was determined to perform well during firing of an electron beam. A contamination monitor recorded matter accretion to be dependent on the solar orientation of the Orbiter. Finally, the distribution of the responsibilities and tasks for mission management are reviewed.

Kissin, K.↗

NASA NTRS1984

Electrical research on solar cells and photovoltaic materials

The flat-plate solar cell array program which increases the service lifetime of the photovoltaic modules used for terrestrial energy applications is discussed. The current-voltage response characteristics of the solar cells encapsulated in the modules degrade with service time and this degradation places a limitation on the useful lifetime of the modules. The most desirable flat-plate array system involves solar cells consisting of highly polarizable materials with similar electrochemical potentials where the cells are encapsulated in polymers in which ionic concentrations and mobilities are negligibly small. Another possible mechanism limiting the service lifetime of the photovoltaic modules is the gradual loss of the electrical insulation characteristics of the polymer pottant due to water absorption or due to polymer degradation from light or heat effects. The mechanical properties of various polymer pottant materials and of electrochemical corrosion mechanisms in solar cell material are as follows: (1) electrical and ionic resistivity; (2) water absorption kinetics and water solubility limits; and (3) corrosion characterization of various metallization systems used in solar cell construction.

Orehotsky, J.↗