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Results for “Van Allen belts”

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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1964

Particle populations in space.

Space radiation flux, composition and energy spectra data that must be considered in design of manned spacecraft

COSMIC RADIATION↗
NASA NTRS1973

Optimal low thrust geocentric transfer

A computer code which will rapidly calculate time-optimal low thrust transfers is being developed as a mission analysis tool. The final program will apply to NEP or SEP missions and will include a variety of environmental effects. The current program assumes constant acceleration. The oblateness effect and shadowing may be included. Detailed state and costate equations are given for the thrust effect, oblateness effect, and shadowing. A simple but adequate model yields analytical formulas for power degradation due to the Van Allen radiation belts for SEP missions. The program avoids the classical singularities by the use of equinoctial orbital elements. Kryloff-Bogoliuboff averaging is used to facilitate rapid calculation. Results for selected cases using the current program are given.

Edelbaum, T. N.↗
NASA NTRS1975

Jovian magnetic fields is complex, Pioneer 11 shows

An analysis of the magnetic field of the planet Jupiter is presented. The data are based on the information returned by Pioneer 11 space probe. It was determined that the magnetic field stretches across 9 million miles of space at some times and shrinks in volume by three-fourths or more at other times. It was also determined that electrons trapped in the magnetic field of Jupiter are 10,000 times more intense than those in the Van Allen radiation belts which circle the earth. Additional data were obtained on the polar regions, atmospheric circulation, and the nature of the moons.

Panagakos, N.↗
NASA NTRS1976

Effects of 1- and 2-MeV electrons on photomultiplier tubes

Various types of photomultiplier tubes useful for space applications were irradiated with 1- and 2-MeV electrons at Van Allen radiation belt fluxes of 100,000 to 10 millions electrons/sq cm-sec. The increase in the dark current due to electron irradiation was observed at various bias voltages under worst-case conditions (no shielding). Results were presented in the form of dark current plotted against electron flux. All the tubes tested showed extremely large increases in dark current. Tube types 541A, 6217, 6199, and 6903 exhibited the largest increases under irradiation, whereas type 1P22 was affected the least. All the damage observed was transient. The luminescence produced in the optical window probably accounts for a large part of the dark-current increases, but there were some effects possibly due to direct irradiation of the photocathode and dynode chain.

Beatty, M. E., III↗
NASA NTRS1976

Payload influences on technology development and utilization of the Space Shuttle extravehicular mobility unit

Historical EVA approaches are examined. The considered data emphasize the overall importance of EVA for Shuttle payload operations. Twenty requirement categories related to crew protection, crew performance, and payload protection are listed in a table. Attention is given to a preliminary assessment of payload related requirements, an evaluation of the natural thermal environment in the case of the Shuttle orbiter bay, and the ability of the extravehicular mobility unit (EMU) to protect the crewman from induced or natural radiation as found in the Van Allen radiation belt South Atlantic anomaly. On the basis of the evaluation it appears very likely that design improvements alone can make the EMU meet payload requirements without requiring significant technology advances.

Patrick, J. W.↗
NASA NTRS1980

Orbit to orbit transportation

Orbital transfer vehicle propulsion options for SPS include both chemical (COTV) and electrical (EOTV) options. The proposed EOTV construction method is similar to that of the SPS and, by the addition of a transmitting antenna, may serve as a demonstration or precursor satellite option. The results of the studies led to the selection of a single stage COTV for crew and priority cargo transfer. An EOTV concept is favored for cargo transfer because of the more favorable orbital burden factor over chemical systems. The gallium arsenide solar array is favored over the silicon array because of its self annealing characteristics of radiation damage encountered during multiple transitions through the Van Allen radiation belt. Transportation system operations are depicted. A heavy lift launch vehicle (HLLV) delivers cargo and propellants to LEO, which are transferred to a dedicated EOTV by means of an intraorbit transfer vehicle (IOTV) for subsequent transfer to GEO. The space shuttle is used for crew transfer from Earth to LEO. At the LEO base, the crew module is removed from the shuttle cargo bay and mated to a COTV for transfer to GEO. Upon arrival at GEO, the SPS construction cargo is transferred from the EOTV to the SPS construction base by IOTV. Crew consumables and resupply propellants are transported to GEO by the EOTV. Transportation requirements are dominated by the vast quantity of materials to be transported to LEO and GEO.

Bergeron, R. P.↗
NASA NTRS1984

Trapped-proton energy spectrum determination (M0002-1)

The objective of this experiment is to measure the flux and energy spectrum of protons with energies of 1 to MeV. These protons are trapped on the Earth's magnetic field lines as part of the inner radiation belt, or Van Allen zone. The proton will be encountered predominantly in the South Atlantic anomaly at a 90 deg pitch angle.

Frederick J Rich↗
NASA NTRS1983

Space power system utilizing Fresnel lenses for solar power and also thermal energy storage

A solar power plant suitable for earth orbits passing through Van Allen radiation belts is described. The solar-to-electricity conversion efficiency is estimated to be around 9 percent, and the expected power-to-weight ratio is competitive with photovoltaic arrays. The system is designed to be self-contained, to be indifferent to radiation belt exposures, store energy for periods when the orbiting system is in earth shadow (so that power generation is contant), have no moving parts and no working fluids, and be robust against micrometeorite attack. No electrical batteries are required.

Turner, R. H.↗
NASA NTRS1986

Alternative power generation concepts for space

Trade and optimization studies that highlight the potential of solar and nuclear dynamic systems relative to photovoltaic power systems are summarized. The solar dynamic case is the LEO Stirling system, while the nuclear system is the SP-100 system goal. Nuclear systems have the potential for the lightest weight, least area, sunlight independent, radiation-durable system. Solar dynamic systems pose a stiff challenge to photovoltaic systems in the midaltitudes because of their insensitivity to the Van Allen radiation belts. While the initial operational capability space station power system is only slightly superior to the SOA PV system, with development focused on the key technologies, advanced solar dynamic systems are fully competitive in LEO midaltitudes with the advanced photovoltaic systems. Advances in energy storage systems (100 Whrs/kg required) are essential.

Brandhorst, Henry W., Jr.↗
NASA NTRS1987

An update on the Active Magnetospheric Particle Tracer Explorers (AMPTE) program

The principles involved in the AMPTE mission's active experiments are discussed together with the role of the AMPTE satellites (the Germany's Ion Release Module, IRM, the United Kingdom Subsatellite, and the U.S Charge Composition Explorer, CCE) in and the results of the ion-release experiments. The AMPTE orbit profile is described, with the times of solar-wind and magnetotail ion releases (two barium and two lithium releases were carried out as the IRM precessed through the magnetosheath) shown schematically. In addition to the results on the Van Allen radiation belts obtained through the ion-release experiments, studies of the radiation belts with the new generation of sensors aboard the CCE and IRM are described.

Mcentire, Richard W.↗
NASA NTRS1989

Correlation studies between solar wind parameters and the decimetric radio emission from Jupiter

Results of a study comparing long-term time variations in Jupiter's synchrotron radio emission with a variety of solar wind parameters and the 10.7 cm solar flux are reported. Data from 1963 through 1985 were analyzed, and the results suggest that many solar wind parameters are correlated with the intensity of the synchrotron emission produced by the relativistic electrons in the Jovian Van Allen radiation belts. Significant nonzero correlation coefficients appear to be associated with solar wind ion density, ram pressure, thermal pressure, flow velocity, momentum, and ion temperature. The implication of these results is that the solar wind is influencing the supply and/or loss of electrons to Jupiter's inner magnetosphere.

Bolton, S. J.↗