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Results for “VAN ALLEN BELT”

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 127 records · Page 7
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NASA NTRS1972

A summary of the OV1-19 satellite dose, depth dose, and linear energy transfer spectral measurements

Measurements of the biophysical and physical parameters in the near earth space environment, specifically, the Inner Van Allen Belt are discussed. This region of space is of great interest to planners of the Skylab and the Space Station programs because of the high energy proton environment, especially during periods of increased solar activity. Many physical measurements of charged particle flux, spectra, and pitch angle distribution have been conducted and are programmed in the space radiation environment. Such predictions are not sufficient to accurately predict the effects of space radiations on critical biological and electronic systems operating in these environments. Some of the difficulties encountered in transferring from physical data to a prediction of the effects of space radiation on operational systems are discussed.

Cervini, J. T.↗
NASA NTRS1972

Freedom to act fast.

The history of the development program that culminated in the Explorer and Pioneer launchings is outlined. Earlier work on launching rockets, and the discovery of the Van Allen belts is discussed. The Explorer program was carried out in less than three months, and the different Explorers launched later carried widely different payloads.

Pickering, W. H.↗
NASA NTRS1973

Apollo experience report: Protection against radiation

Radiation protection problems on earth and in space are discussed. Flight through the Van Allen belts and into space beyond the geomagnetic shielding was recognized as hazardous before the advent of manned space flight. Specialized dosimetry systems were developed for use on the Apollo spacecraft, and systems for solar-particle-event warning and dose projection were devised. Radiation sources of manmade origin on board the Apollo spacecraft present additional problems. Methods applied to evaluate and control or avoid the various Apollo radiation hazards are discussed.

English, R. A.↗
NASA NTRS1972

Calculations of neutron flux spectra induced in the earth's atmosphere by galactic cosmic rays

Calculations have been carried out to determine the neutron flux induced in the earth's atmosphere by galactic protons and alpha particles at solar minimum for a geomagnetic latitude of 42 N. Neutron flux spectra were calculated using Monte Carlo and discrete ordinates methods, and various comparisons with experimental data are presented. The magnitude and shape of the calculated neutron-leakage spectrum at the particular latitude considered support the theory that the cosmic-ray-albedo-neutron-decay mechanism is the source of the protons and electrons trapped in the Van Allen belts.

Armstrong, T. W.↗
NASA NTRS1972

Shielding of manned space vehicles against protons and alpha particles

The available information on the shielding of manned space vehicles against protons and alpha particles is summarized. The emphasis is placed on shielding against Van Allen belt protons and against solar-flare protons and alpha particles, but information on shielding against galactic cosmic rays is also presented. The approximation methods for use by nonexperts in the space shielding field are those that are standard in the space shielding literature.

Alsmiller, R. G., Jr.↗
NASA NTRS1973

Jupiter's outer atmosphere.

The current state of the theory of Jupiter's outer atmosphere is briefly reviewed. The similarities and dissimilarities between the terrestrial and Jovian upper atmospheres are discussed, including the interaction of the solar wind with the planetary magnetic fields. Estimates of Jovian parameters are given, including magnetosphere and auroral zone sizes, ionospheric conductivity, energy inputs, and solar wind parameters at Jupiter. The influence of the large centrifugal force on the cold plasma distribution is considered. The Jovian Van Allen belt is attributed to solar wind particles diffused in toward the planet by dynamo electric fields from ionospheric neutral winds, and the consequences of this theory are indicated.

Brice, N. M.↗
NASA NTRS1973

Documentation of the data analysis system for the gamma ray monitor aboard OSO-H

The programming system is presented which was developed to prepare the data from the gamma ray monitor on OSO-7 for scientific analysis. The detector, data, and objectives are described in detail. Programs presented include; FEEDER, PASS-1, CAL1, CAL2, PASS-3, Van Allen Belt Predict Program, Computation Center Plot Routine, and Response Function Programs.

Croteau, S.↗
NASA NTRS1975

An analysis of space environment effects on performance and missions of a Solar Electric Propulsion Stage (SEPS)

The development of an analysis which addresses the problems of degrading space environmental effects on the performance and missions of a Solar Electric Propulsion Stage (SEPS) is reported. A detailed study concerning the degrading effects of the Van Allen Belt charged-particle radiation on specific spacecraft subsystems is included, along with some of the thermal problems caused by electromagnetic radiation from the sun. The analytical methods used require the integration of two distinct analyses. The first, is a low-thrust trajectory analysis which uses analytical approximations to optimum steering for orbit raising, including three-dimensional plane change cases. The second is the conversion of the Vette time-averaged differential energy spectra for protons and electrons into a 1-MeV electron equivalent environment as a function of spatial position and thickness of various shielding materials and solar-cell cover slides.

Mcglathery, D. M.↗
NASA NTRS1975

Composition and energy spectra of heavy nuclei of unknown origin detected on Skylab

Lexan track detectors with large collecting power were exposed inside and outside Skylab during late 1973 and early 1974. Steeply falling energy spectra of nuclei with Z greater than or equal to 8 and energies between 10 and 40 MeV were observed at intensities much higher than those observed outside the magnetosphere. Four possible sources (solar flare particles; low-energy cosmic rays; the anomalous component of low-energy cosmic rays; particles trapped in the inner Van Allen belt) are examined using Skylab particle flux data outside the magnetosphere and other measurements. The composition is found to be most consistent with that of the solar corona. It is suggested that heavy solar wind ions enter the magnetosphere, are accelerated, and populate the inner radiation belt.

Chan, J. H.↗
NASA NTRS1975

What we have learned from the magnetosphere

Three significant discoveries resulting from recent studies of earth's magnetosphere are discussed: (1) the central role of magnetic-field-line reconnection in determining the topology, geometry, and dynamics of the magnetosphere; (2) the realization that auroral arcs result from coupling of solar-wind stresses to the ionosphere and neutral atmosphere; and (3) the role of plasma turbulence in affecting both the microscopic state and macroscopic observables of the magnetospheric plasma. Magnetic-field-line reconnection is described in terms of Dungey's (1961) model of the magnetosphere, a simple picture of magnetic-substorm evolution is outlined, and questions concerning the reconnection rate are considered. The production of aurorae by field-aligned electron beams is examined, and an analogy is made between earth's magnetosphere and that of a pulsar with aligned dipole and spin axes. Plasma-turbulence problems are reviewed which concern anomalously fast electron and proton losses from the Van Allen belts, whistler-electron interactions, and anomalous resistance in auroral arcs. The Pioneer 10 encounter with Jupiter's magnetosphere is briefly noted.

Kennel, C. F.↗
NASA NTRS1976

A telescope for the Infrared Astronomical Satellite /IRAS/

The Infrared Astronomical Satellite (IRAS) will be used to survey the 8 to 120 micron spectrum of the entire sky to the faintest flux levels possible by using state-of-the-art detectors and preamplifiers. As a result of a recently completed study of the telescope and focal plane, a concept has been devised that demonstrates the feasibility of using stored cryogen to cool the telescope for one year of operation in a polar twilight orbit at an altitude of 900 km. Predictions regarding noise equivalent flux density, cryogenic lifetime, and the number of noise spikes caused by Van Allen belt radiation are presented. The telescope is cooled both by supercritical and by superfluid helium. The on-board signal processing includes provisions for suppressing noise spikes.

Hedden, R. L.↗
NASA NTRS1978

Magnetospheric substorms

The generation of magnetospheric substorms as a magnetospheric response to a rectangular wave of a component of the interplanetary magnetic field is discussed. The development and decay of auroral substorms (the only visible manifestations of magnetic substorms) are described with reference to auroral particle precipitation, joule heat dissipation, and ring current injection. Various models of substorm phenomena are reviewed, including: (1) the conversion of magnetotail magnetic energy, (2) hot plasma injection from the plasma sheet into the Van Allen belt and ring current formation, (3) field-aligned currents and the auroral electrojet, and (4) the nature of interplanetary magnetic field fluctuations.

Akasofu, S.-I.↗
NASA NTRS1978

The earth: 1 - The upper atmosphere, ionosphere and magnetosphere

Hydrogen in the upper atmosphere is considered, taking into account an identification of the geocorona, theoretical altitude distributions, theoretical diurnal variations, ion-neutral interactions, radiative transfer theory, optical observations, nonoptical observations, deuterium, observational results, the ionization of the nighttime D and E regions, and H and D around Venus, Mars, and Jupiter. The equatorial electrojet is discussed along with electron plasma resonances in the topside ionosphere. Attention is also given to observations with respect to auroral particle precipitation, observations and theory concerning polar-cap absorption, and the physical mechanisms of the inner Van Allen Belt.

Gordon, C. W.↗
NASA NTRS1979

A search for the interplanetary quantity controlling the development of geomagnetic storms

An historical account is presented concerning the evolution of our present concept of geomagnetic storms. The present concept was formulated by Chapman (1927) in his magnetic data statistical studies of 'the initial rise' (now termed the initial phase) 'and subsequent larger decrease' (now termed the main phase) in H, followed by 'slow recovery'. The concept introduced by Alfven in 1940 of guiding center motions of a charged particle in a nonuniform magnetic field (ring currents) is also discussed. By 1963 it became quite certain that the ring current, namely a storm-time Van Allen belt, is formed in the magnetosphere during the storm's main phase. The search then began for the solar wind quantity controlling the development of the main phase. The author then gives a personal account of how our concept of geomagnetic storms has advanced and how new findings based on satellite and ground-based observations have made it possible to arrive at a first-approximation expression for the interplanetary quantity controlling the development of geomagnetic storms. Since a geomagnetic storm is a magnetic manifestation of a magnetospheric storm, which is a nonlinear superposition of intense magnetospheric substorms, the main emphasis is shifted toward the understanding of magnetospheric substorms in order to arrive at the parameters controlling the development of geomagnetic storms.

Akasofu, S.-I.↗
NASA NTRS1978

Characterization and modeling of radiation effects NASA/MSFC semiconductor devices

A literature review of the near-Earth trapped radiation of the Van Allen Belts, the radiation within the solar system resulting from the solar wind, and the cosmic radiation levels of deep space showed that a reasonable simulation of space radiation, particularly the Earth orbital environment, could be simulated in the laboratory by proton bombardment. A 3 MeV proton accelerator was used to irradiate CMOS integrated circuits fabricated from three different processes. The drain current and output voltage for three inverters was recorded as the input voltage was swept from zero to ten volts after each successive irradiation. Device parameters were extracted. Possible damage mechanisms are discussed and recommendations for improved radiation hardness are suggested.

Kerns, D. V., Jr.↗
NASA NTRS1984

The effect of radiation on the IRAS all-sky survey

The Infrared Astronomical Satellite (IRAS) is in a sun synchronous, 'near' polar orbit at an altitude of 900 km. The primary objective of IRAS is related to the conduction of an all-sky survey in the wavelength range from 8 microns to 120 microns. The present investigation is concerned with three components of the radiation environment encountered by IRAS, taking into account the high energy protons in the South Atlantic Anomaly, high energy electrons in the horns of the Van Allen belts, and cosmic rays. The effect of radiation on the returned data stream is studied, and attention is given to the steps which were taken to minimize the impact of radiation on the completeness of the survey.

Wolff, D. M.↗
NASA NTRS1984

The calibration of photographic and spectroscopic films: A densitometric analysis of IIaO film flown aboard the Space Shuttle 3

Three canisters of IIaO film were prepared along with packets of color film from the National Geographic Society, which were placed on the Space Shuttle. The ultimate aim was to obtain reasonably accurate data concerning the background fogging effects as related to the total environment experience of the film including the groundbased packing and loading of the film from Goddard Space Flight Center to Cape Kennedy. The affects of solar wind, humidity, cosmic rays, the Van Allen Belt radiation exposure, various thermal effects, and reentry and off-loading of the film during takeoff and 8 days, 3 hour 15 minute orbit are of particular interest.

Hammond, E. C., Jr.↗
NASA NTRS1985

Waves In Space Plasmas (WISP)

Waves in space plasmas (WISP) utilizes powerful radio transmitters and sensitive receivers to probe the secrets of the magnetosphere, ionosphere and atmosphere. The scientific objective is to achieve a better understanding of the physical processes occurring in these regions. For example, audio frequency radio waves will be radiated from the long WISP antenna, will travel to the outer reaches of the magnetosphere, and will interact with Van Allen belt particles, releasing some of their energy which amplifies the waves. Study of this interaction will give us a better understanding of a major magnetospheric process, wave particle interactions. Radio waves from WISP at higher frequencies (AM radio and beyond) will be reflected by the ionosphere and will, for example, advance our understanding of bubbles in the equatorial ionosphere which affect satellite communications.

Taylor, W. W. L.↗