Search NASA⌕ Search

SEARCH · Search NASA

Results for “solar modules”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Photovoltaic power modules for NASA's manned Space Station

The capability and the safety of manned spacecraft are largely dependent upon reliable electric power systems. Two similar space power systems able to survive the low earth orbit environment, are being considered for NASA's Manned Space Station (SS), scheduled to begin operation in the mid 1990's. The Space Station Electric Power System (EPS) is composed of Photovoltaic (PV) Power Modules, Solar Dynamic (SD) Power Modules, and the Power Management and Distribution (PMAD) System. One EPS configuration will deliver 37.5 kW of PV based, utility grade, ac power to SS users. A second 75 kWe PV based EPS option is also being considered for SS deployment. The two EPS options utilize common modules and differ only in the total number of PV Power Modules used. Each PV Power Module supplies 18.75 kWe of ac power and incorporates its own energy storage and thermal control. The general requirements and the current preliminary design configuration of the Space Station PV Power Modules are examined.

Tatro, C. A.↗
NASA NTRS1991

Cosmic ray transport - Modulation and the anomalous component

Cosmic ray transport research is reviewed for the 1987-1990 time period, focusing on diffusive transport. Problems discussed include the diffusion model, anomalous components, radial gradient and north south anisotropy, short term modulation, long-term solar modulation, and charge sign dependent modulation.

Evenson, Paul↗
NASA NTRS1995

Pick-up ion pressure gradients modulating the solar wind dynamics

Neutral interstellar atoms penetrate deeply into the inner heliosphere before they become ionized by various processes. As ions they are picked-up by the frozen-in magnetic fields and are convected outwards with the solar wind plasma. Thereby the primary plasma flow is mass, momentum, and energy-loaded. The dynamics of the distant multi-constituent solar wind is, however, not solely determined by these loading processes, but is also affected by the wave-mediated pick-up ion pressure gradients derivable from the pick-up ion distribution function. The action of the radial components of these pressures essentially counter balances the decelerating effect of the solar wind momentum loading, diminishing strongly the deceleration of the distant solar wind. Furthermore the latitudinal components of the pick-up ion pressures induce latitudinal forces acting on the multiconstituent solar plasma outflow and inducing nonradial bulk flow components. The enforced nonradial outflow geometry on the upwind hemisphere may partly be responsible for the magnetic flux deficit which was claimed since several years in the PIONEER-10 magnetic flux data.

Fahr, Hans J.↗
NASA NTRS1973

Solar and geomagnetic modulation of low-energy secondary cosmic ray electrons.

Balloon exposures of hodoscope instruments at Churchill, Manitoba; Minneapolis, Minnesota; and Sioux Falls, South Dakota, have established that the flux of return albedo electrons does not depend upon launch latitude and varies with solar modulation in proportion to the intensity of atmospheric secondary electrons. Only one flight out of 21 showed any indication of a magnetospheric electron flux significantly in excess of that attributable to albedo. Diurnal changes in geomagnetic cutoffs exhibit marked variability from day to day, as was illustrated by one flight in which a low cutoff was observed at Churchill throughout the daytime hours. The intensity increase of 15- to 65-MeV primary cosmic ray electrons due to solar modulation was no more than a factor of 2 from 1969-1970 to 1971.

Luhmann, J. G.↗
NASA NTRS1981

Effects of drift on the transport of cosmic rays. IV - Modulation by a wavy interplanetary current sheet

The effect of a wavy interplanetary current sheet on the solar modulation of galactic cosmic rays is studied. A simple model of the heliospheric magnetic field is employed in which there is an Archimedean spiral magnetic field directed in one direction above the current sheet and another direction below. The current sheet itself is taken to be the extension by the solar wind of a surface that, at the sun, is a plane inclined at an angle alpha to the solar equator. Two magnetic sectors will therefore be seen by an observer within an angle alpha of the heliographic equator. A simple approximate model is used to investigate modulation. As the tilt angle alpha is increased from zero, it is found that the cosmic-ray intensity decreases. For reasonable variation of alpha from approximately 10 deg to approximately 30 deg, the change in intensity can be compared to that observed as one goes from solar minimum to solar maximum. It is concluded that changes in the waviness of the interplanetary current sheet can have an important, and perhaps dominant, effect in producing solar modulation of galactic cosmic rays.

Jokipii, J. R.↗
NASA NTRS2008

The Bess Investigation of the Origin of Cosmic-ray Antiprotons and Search for Cosmological Antimatter

The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) collaboration has made precise measurements of the spectra of cosmic ray antiprotons and light nuclei and conducted a sensitive search for antinuclei. Ten BESS high-latitude flights, eight from Canada and two from Antarctica, span more than a Solar cycle between 1993 and 2007/2008. BESS measurements of low-energy antiprotons constrain candidate models for dark matter including the possible signature of primordial black hole evaporation. The stringent BESS measurements of antiprotons and the elemental and isotopic spectra of H and He provide strong constraints on models of cosmic-ray transport in the Galaxy and Solar System. BESS has also reported the first antideuterium upper limit. BESS employs a superconducting magnetic-rigity spectrometer with time-of-flight and aerogel Cherenkov detectors to identify incident particles by charge, charge sign, mass, and energy. The BESS-Polar long-duration instrument has reduced lower energy limit of 100 MeV (top of the atmosphere) to increase its sensitivity to possible primary antiproton sources. BESS-Polar II was rebuilt with extended magnet lifetime, improved detector and electronic performance, and greater data storage capacity. It was flown fro Antarctica December 2007-January 2008, recording about 4.6 bission events during 24.5 days at float altitude with the magnet on. During the flight the influence of a high-speed stream in the Solar wind was observed. Details of the BESS-Polar II instrument and flight performance are reported elsewhere at this conference. The successful BESS-Polar II flight at Solar minimum is especially important. Most cosmic-ray antiprotons are secondary products of nuclear interactions of primary cosmic-ray nuclei with the interstellar gas, giving a spectrum that peaks at about 2 GeV and falls rapidly to higher and lower energies. However, BESS data taken in the previous Solar minimum show a small excess over secondary expectations at low energies, possibly suggesting the presence of an additional component that may be masked at higher levels of Solar modulation. The high-statistics Solar minimum data obtained by BESS-Polar II will provide a difinitive test of this component. We will review the BESS program and report the latest results including the antiproton and proton spectra measured in the BESS-Polar I flight, the search for cosmic antinuclei, and the status of the BESS-Polar II analysis.

Mitchell, John↗
NASA NTRS1994

Study of cosmic-ray H and He isotopes at 23 AU

We have measured the spectra of H and He isotopes during the 1987 solar minimum with the cosmic-ray detector system (CRS) on the Voyager 2 spacecraft. By carrying out the measurement near solar minimum and at large heliospheric distances, the effects of solar modulations were reduced. In particular, the adiabatic energy losses were smaller, and these results from 23 AU over the solar minimum period of cycle 21 represent observations at energies not accessible from previous measurements near 1 AU. The modulated spectra with the diffusion coefficient constant k(sub 0) = 3.15 x 10(exp 22) sq cm/s (which corresponds to a solar modulation parameter of 360 MV at 23 AU and 500 MV at 1 AU) agree well with both our data at 23 AU and the previous solar minimum measurements at 1 AU. The measured H-1 and H-2 spectra are both consistent with the calculated spectra, using standard Galactic and heliospheric propagation models without invoking an anomalous hydrogen component. With the fixed modulation parameter of 360 MV, the mean pathlengths, source spectra, and cross sections were varied to study the effects of different input parameters on the spectra and relative abundances. At this stage of our work, we have not found any strong evidence from the low-energy H-2 and He-3 data that H-1 and He-4 should have a different propagation history, or different types of source spectra from the heavier cosmic-ray nuclei.

Seo, E. S.↗
NASA NTRS1982

Transfer of Strings to the Module Fixture

Work station for transferring entire strings of solar cells places successive strings alined, with offset, or reversed end for end. Thus, various solar module formats can be accommodated. Two vacuum cups hold each solar cell in string being transferred.

Frasch, W.↗
NASA NTRS1985

The large-scale modulation of cosmic rays in mid-1982: Its dependence on heliospheric longitude and radius

Near solar maximum, a series of large radial solar wind shocks in June and July 1982 provided a unique opportunity to study the solar modulation of galactic cosmic rays with an array of spacecraft widely separated both in heliocentric radius and longitude. By eliminating hysteresis effects it is possible to begin to separate radial and azimuthal effects in the outer heliosphere. On the large scale, changes in modulation (both the increasing and recovery phases) propagate outward at close to the solar wind velocity, except for the near-term effects of solar wind shocks, which may propagate at a significantly higher velocity. In the outer heliosphere, azimuthal effects are small in comparison with radial effects for large-scale modulation at solar maximum.

Pyle, K. R.↗
NASA NTRS1986

Development of flight ready fifty-micron-thick silicon solar cell array module technology

The development of ultrathin silicon solar cell array modules from initial design to flight testing is discussed. Three 80-cell modules were subjected to the thermal soak test, the LEO thermal cycle test, and the solar array flight experiment, and six 48-cell welded modules were evaluated in the geosynchronous orbit thermal cycle test. It is observed that the electrical performance of the modules was not affected by the different environmental conditions. The automatic assembly of the cell modules, in particular the welding and solar cell glassing operation, is described. The specific power capabilities of Kapton, Kapton-Kevlar-Kapton, Kapton-graphite-Kapton, and Kapton-graphite-aluminum honeycomb-graphite solar array designs are assessed.

Patterson, R. E.↗
NASA NTRS1977

Solar particle propagation from 1 to 5 AU

The radial variation of the interplanetary propagation of solar cosmic rays is investigated on a grand scale by performing a statistical analysis of charged-particle data obtained by Pioneers 10 and 11 from launch to Jovian encounter (i.e., at distances of 1 to 5 AU). A numerical propagation model is adopted which includes diffusion, convection, and adiabatic deceleration, as well as a variable power-law diffusion coefficient. The study of solar particle events is carried out by analyzing individually each of five key parameters that are uniquely defined in each solar particle event: the time to maximum flux starting from the initial release at the sun, the anisotropy at the time to maximum flux, the flux at that time, the time width of the event at half the flux at the time to maximum, and the decay time. Combined results for the proton energy ranges from 3.4 to 5.2 MeV and 24 to 30 MeV are presented, the average radial diffusion coefficients between 1 and 5 AU are determined for each energy range, and it is found that the combination of a near-impusive injection with a temporally constant spectral index produces a reasonably good fit to the high-energy data but not as good a fit to the low-energy data. Implications of the results obtained are discussed for cosmic-ray propagation theory, solar modulation studies, and interplanetary acceleration of solar particles.

Zwickl, R. D.↗
NASA NTRS2005

Wave-driven Equatorial Annual Oscillation Induced and Modulated by the Solar Cycle

Our model for the solar cycle (SC) modulation of the Quasi-Biennial Oscillation (QBO) produces a hemispherically symmetric 12-month Annual Oscillation (AO) in the zonal winds, which is confined to low latitudes. This Equatorial Annual Oscillation (EAO) is produced by interaction between the anti-symmetric component of SC forcing and the dominant anti-symmetric AO. The EA0 is amplified by the upward propagating small- scale gravity waves (GW), and the oscillation propagates down through the stratosphere like the QBO. The amplitude of the EA0 is relatively small, but its SC modulation contributes significantly to extend the effect to lower altitudes. Although the energy of the EA0 is concentrated at low latitudes, prominent signatures appear in the Polar Regions where the SC produces measurable temperature variations. At lower altitudes, the SC effects are significantly different in the two hemispheres because of the EAO, and due to its GW driven downward propagation the phase of the annual cycle is delayed.

Mayr, Hans G.↗
NASA NTRS1975

The solar cycle variation in the solar wind and the modulation of cosmic rays

Evidence for a solar cycle variation in the interplanetary plasma is presented based on direct observations of the solar wind by the Pioneer and Vela spacecraft. These data indicate that between 1965 and 1971 there were more days associated with high speed streams during solar maximum than during solar minimum. These observations provide the first observational explanation for the solar modulation of cosmic rays. At solar maximum the probability is highest that cosmic rays entering the solar system will encounter high speed streams. As a result, there is more modulation of cosmic rays at solar maximum than at other times.

Intriligator, D. S.↗
NASA NTRSDate not supplied

Trajectory Design for a Solar Necklace of Repurposed Gateway Logistics Modules

The Solar Necklace mission concept, initially formed from a study conducted by the Compass Team at NASA’s Glenn Research Center, aims to maximize the scientific potential of a spacecraft’s lifetime by redefining their proposed disposal trajectories. By repurposing logistics modules (LMs) initially designated for heliocentric disposal after servicing NASA’s Gateway, a constellation of spacecraft could be placed around the sun. This paper assesses the feasibility of reusing vehicles equipped with solar science packages, sending them into a heliocentric orbit to enhance solar science capabilities, and potentially provide early warning capabilities for future piloted spacecraft. A comprehensive analysis of the trajectory design aspects for the Solar Necklace mission was performed, highlighting key components of the study such as Earth-relative drift rates, ∆v requirements, Earth-flyby opportunities, number of lunar flybys, and final orbital state parameters. Additionally, the paper serves as a proof-of-concept for the repurposing of Gateway LMs using convenient, low-cost methods of advancing solar science, space weather understanding, and climate research.

Mission Design↗
NASA NTRS1994

Galactic cosmic ray composition and energy spectra

Galactic cosmic ray nuclei represent a significant risk to long-duration spaceflight outside the magnetosphere. We review briefly existing measurements of the composition and energy spectra of heavy cosmic ray nuclei, pointing out which species and energy ranges are most critical to assessing cosmic ray risks for spaceflight. Key data sets are identified and a table of cosmic ray abundances is presented for elements from H to Ni (Z = 1 to 28). Because of the 22-year nature of the solar modulation cycle, data from the approaching 1998 solar minimum is especially important to reducing uncertainties in the cosmic ray radiation hazard. It is recommended that efforts to model this hazard take advantage of approaches that have been developed to model the astrophysical aspects of cosmic rays.

Mewaldt, R. A.↗
NASA NTRS1975

A thruster sub-system module /TSSM/ for solar electric propulsion

The thruster subsystem module (TSSM) considered for solar electric propulsion (SEP) missions is to consist of a 30-cm ion thruster, a thruster gimbal system, a propellant storage and feed system, a power processing unit, a modular thermal control system, and a modular support structure. TSSM design requirements are considered along with a TSSM general design approach. It is pointed out that a TSSM for SEP missions can be designed and built based on existing technology.

Sharp, G. R.↗