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At least 1,045 records · Page 58

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NASA NTRS1981

A meeting with the universe: Science discoveries from the space program

A general history of space exploration is presented. The solar system is discussed. The Sun-Earth relationship is considered, including magnetic fields, solar wind, the magnetosphere, and the Sun-weather relationship. The universe beyond the solar system is discussed. Topics include stellar and galactic evolution, quasars and intergalactic space. The effects of weightlessness and ionizing radiation on human beings are considered. The possibility of extraterrestrial life is discussed. Lunar and planetary exploration, solar-terrestrial physics, astrophysics, biomedical research and exobiology are reviewed. Numerons color illustrations are included.

French, B. M.↗

NASA NTRS1982

Aging and space travel

The matter of aging and its relation to space vehicle crewmembers undertaking prolonged space missions is addressed. The capabilities of the older space traveler to recover from bone demineralization and muscle atrophy are discussed. Certain advantages of the older person are noted, for example, a greater tolerance of monotony and repetitious activities. Additional parameters are delineated including the cardiovascular system, the reproductive system, ionizing radiation, performance, and group dynamics.

Mohler, S. R.↗

NASA NTRS1982

Plant seeds in biological research in space

Data of 15 years of space flight and laboratory tests of plant seeds of 20 species, mainly on the combined and separate effects of launch vibration, ionizing radiation and weightlessness, are surveyed. It is concluded that plants do not show a pronounced response to space flight factors. Conditions of return to Earth, the number of heavy cosmic ray particles striking biological targets and effects of change in magnetic an electromagnetic fields have been little studied, and that more study of growing plants in space is needed.

Miller, A. T.↗

NASA NTRS1983

The problem of cooling the cold Io torus

Two models are developed for the transport of ions inward from Io's orbit, the first using the assumption that radial diffusion is the dominant transport mechanism while the second uses a combination of diffusive and convective transport. The models include thermal and number density transport, radiation, ionization and pickup of local neutrals, recombination, charge exchange, and Coulomb interactions. It is found that pure diffusive transport can account for the dramatic inward depletion of the torus only by invoking recombination or by postulating a massive increase in the production rate of torus ions sometime prior to the Voyager mission. Recombination is determined to be far too slow to be the cause of the observed density decrease inside of Io. The model combining convection and diffusion is shown to reasonably match the data, but only if a diffusion coefficient 100 times less than that derived from Pioneer observations is used. In addition, it is shown that the Pioneer derived diffusion rate combined with Voyager temperature and density measurements indicate a large nonradiative sink of energy in the inner torus.

Richardson, J. D.↗

NASA NTRS1983

The nature of NML Cygnus

Since the discovery of NML Cyg by Neugebauer et al. (1965), its nature has been uncertain because its distance and luminosity are not known. NML Cyg is partially surrounded by an H II region which is heavily obscured by intervening interstellar matter. This H II region has been mapped in the continuum at 21 cm, and it seems clearly associated with the star. In the present investigation it is proposed that the H II region has been created by ionizing radiation from the Cyg OB2 association. The close agreement between the observed structure of the H II region and that predicted by the considered model provides strong evidence that NML Cyg is indeed at the distance of the association, 2 kpc. At this distance it is among the most luminous red stars shown. Because of its high luminosity, NML Cygnus is probably a massive star of perhaps 50 solar masses.

Morris, M.↗

NASA NTRS1982

Role of succinic acid in chemical evolution

Succinic acid is converted into other carboxylic acids by ionizing radiation. The results obtained have been correlated with the ready formation of this compound in prebiotic experiments. Its role in biological systems may be related to its prebiotic occurrence.

Negron-Mendoza, A.↗

NASA NTRS1983

Dependence of radio emission in large H alpha flares 1967-1970 upon the orientation of the local solar magnetic field

Published data on ionizing radiation (as reflected in sudden ionospheric disturbances), H-alpha importance, 10-cm flux, dynamic spectrum, and 200-MHz flux are analyzed for a group of 84 solar flares (from 1967 to 1970) classified by Pudovkin and Chertkov (1976). The group consists of 29 flares with southern orientation of the 100,000-km-scale overlying magnetic field, 32 with northern orientation, and 23 with indeterminate orientation; all have H-alpha importance greater than about 2. Slightly greater X-ray and optical emissions, but one-order-of-magnitude greater prompt 200-MHz and 10-cm fluxes are found in southern as compared to northern-oriented flares. It is inferred that the amount of electromagnetic flare energy radiated promptly from the corona, as compared with that radiated from the chromosphere, was significantly affectly by the orientation of the overlying large-scale magnetic field during the period of observation. This trend is shown to be consistent despite some periodic variation.

Roelof, E. C.↗

NASA NTRS1983

Broad emission lines of QSOs are consistent with rotating supermassive stars

The basic properties of broad emission-line profiles from quasars and Seyfert galaxies are suggested to indicate emissions originating from the surface of a rotating supermassive star. The areal extent of the ionizing luminosity and its energy are calculated, showing that the broad-line region has a mass of about 10 solar masses and a volume filling factor of 1/1,000,000. It is shown that if the broad-line region consists of a layer of ionized gas on the surface of a rotating supermassive star with an equatorial speed of 5,000 km/sec and a relatively cool surface, a layer of photoionized gas will result and emit a line emission per unit area that is proportional to the incident flux of ionizing radiation. The emitting layer will be heated to about 100 million K by an X ray component of a nonthermal continuum over a 10,000 K surface.

Shields, G. A.↗

NASA NTRS1983

Latchup in CMOS devices from heavy ions

It is noted that complementary metal oxide semiconductor (CMOS) microcircuits are inherently latchup prone. The four-layer n-p-n-p structures formed from the parasitic pnp and npn transistors make up a silicon controlled rectifier. If properly biased, this rectifier may be triggered 'ON' by electrical transients, ionizing radiation, or a single heavy ion. This latchup phenomenon might lead to a loss of functionality or device burnout. Results are presented from tests on 19 different device types from six manufacturers which investigate their latchup sensitivity with argon and krypton beams. The parasitic npnp paths are identified in general, and a qualitative rationale is given for latchup susceptibility, along with a latchup cross section for each type of device. Also presented is the correlation between bit-flip sensitivity and latchup susceptibility.

Soliman, K.↗

NASA NTRS1984

Cryogenic telescope on the Infrared Astronomical Satellite (IRAS)

The Infrared Astronomical Satellite (IRAS) has completed an unbiased all-sky survey at wavelengths from 10 to 100 microns. The design and performance of the focal plane array is described with emphasis on in-orbit measurements of the sensitivity and stability. In the four broad spectral bands centered at 12, 25, 60, and 100 microns, the system noise equivalent flux density (NEFD) values are in Jy/(Square root of Hz), 0.03, 0.025, 0.046, and 0.21, respectively (Jansky = 10 to the -26th W/sq m/Hz). For point sources, a single scan at the survey rate of 3.8 arcmin/s yields limiting flux densities at the 3-sigma confidence level of 0.36, 0.30, 0.39, and 1.2 Jy. The dc stability of the junction field effect transistor (JFET) amplifiers and the excellent off-axis rejection of the telescope permit total flux measurements of extended infrared emission at levels below 6,000,000 Jy/sr. Response of the extrinsic silicon and germanium photo-detectors to ionizing radiation is described.

Low, F. J.↗

NASA NTRS1984

Nighttime auroral energy deposition in the middle atmosphere

Ionospheric rocket sounding data for eight nighttime auroral events are used to characterize relativistic electron showers and their effects on atmospheric ozone. The rockets were launched from the Poker Flat Research Range in Alaska and from Andoya, Norway over the period 1976-82. Energetic fluxes were always detected but were of insufficient magnitude to produce significant changes in stratospheric ozone. However, middle atmospheric energy sources were found to be dominated by relativistic electrons and X-ray bremmstrahlung, the latter from 40-55 km and the former from 55-60 km altitudes. The ionizing radiation is concluded to be a significant factor in mesospheric ion conductivity, mobility, electric field structure and analytical models for the ion-neutral chemistry.

Goldberg, R. A.↗

NASA NTRS1986

Testing Electronic Devices for Single-Event Upset

Report prepared describes equipment and summarizes both pretest and onsite procedures for testing of digital electronic devices for susceptibility to single-event upset. Term "single-event upset" denotes variety of temporary or permanent bit flips or latchup induced by single particles of ionizing radiation. Vacuum chamber houses device under test while exposed to ion beam. Vacuum chamber and associated equipment must be brought to ion-beam facility for test.

Nichols, D. K.↗

NASA NTRS1985

Numberical simulation of the effects of radially injected barium plasma in the ionosphere

The morphology of the ion cloud in the radial shaped charge barium injection was studied. The shape of the ion cloud that remains after the explosive products and neutral barium clears away was examined. The ion cloud which has the configuration of a rimless wagon wheel is shown. The major features are the 2.5 km radius black hole in the center of the cloud, the surrounding ring of barium ion and the spokes of barium ionization radiating away from the center. The cloud shows no evolution after it emerges from the neutral debris and it is concluded that it is formed within 5 seconds of the event. A numerical model is used to calculate the motion of ions and electrons subject to the electrostatic and lorenz forces.

Swift, D. W.↗

NASA NTRS1984

The stellar content of 30 Doradus

The components of the supergiant H II region Tarantula are surveyed, noting that 30 Doradus is really only the most active section of the Large Magellanic Cloud. The region contains at least 40 WR stars and numerous non-H II region late spectral type supergiants. Most of the stars are centrally located and presumably feed on the nebulosity. The closeness of the population will require fine spectroscopic scans of all the members to achieve accurate typing. Although the population is mixed, the ionizing radiation emitted by the region is consistent with its classification as part of the H II region. Finally, the brightest objects within Tarantula are suspected of being multiple systems.

Walborn, N. R.↗

NASA NTRS1984

Neoplastic cell transformation by energetic heavy ions and its modification with chemical agents

One of the major deleterious late effects of ionizing radiation is related to the induction of neoplasms. In the present report recent experimental results on neoplastic cell transformation by heavy ions are presented, and possible means to circumvent the carcinogenic effect of space radiation are discussed. Biological effects observed in experiments involving the use of energetic heavy ions accelerated at the Bevalac suggest that many of the biological effects observed in earlier space flight experiments may be due to space radiation, particularly cosmic rays. It is found that the effect of radiation on cell transformation is dose-rate dependent. The frequency of neoplastic transformation for a given dose decreases with a decrease of dose rate of Co-60 gamma rays. It is found that various chemical agents give radiation protection, including DMSO.

Yang, T. C.↗

NASA NTRS1984

Medical ultrasound - From inner space to outer space

During the last decade, medical ultrasound has rapidly become a widely accepted imaging modality used in many medical specialties. It has the advantages that it is noninvasive, does not use ionizing radiation, is relatively inexpensive and is easy to use. Future trends in ultrasound include expanded areas of use, advanced signal processing and digital image analysis including tissue characterization and three-dimensional reconstructions.

Rooney, J. A.↗

NASA NTRS1986

The photoionization of the diffuse galactic gas

In a study of the diffuse ionized gas (DIG) component of the interstellar medium, it is attempted to see if the general properties of dilute gas ionized by O stars are similar to observations and to what extent the observations of the DIG can be used to determine the nature of the ionizing radiation field at great distances above the plane of the Galaxy. It has been suggested by Reynolds (1985) that either shocks or photoionization might be responsible for the DIG. The photoionization model seems required by the observations.

Mathis, J. S.↗

NASA NTRS1986

Toxicological safeguards in the manned Mars missions

Safeguards against toxic chemical exposures during manned Mars missions (MMMs) will be important for the maintenance of crew health and the accomplishment of mission objectives. Potential sources include offgassing, thermodegradation or combustion of materials, metabolic products of crew members, and escape of chemical from containment. Spacecraft maximum allowable concentration (SMAC) limits will have to be established for potential contaminants during the MMMs. The following factors will be used in establishing these limits: duration of mission, simultaneous exposure to other contaminants, deconditioning of crew members after long periods of reduced gravity, and simultaneous exposure to ionizing radiation. Atmospheric contaminant levels in all compartments of the transit spacecraft and Manned Mars Station (MMS) will be monitored at frequent intervals with a real time analyzer. This analyzer will be highly automated, requiring minimal crew time and expertise. The atmospheric analyzer will find other usages during the MMMs such as analyzing Martian atmospheres and soils, exhaled breath and body fluids of crew members, and reaction products in chemical processing facilities.

Coleman, Martin E.↗