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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Physics of sub-micron cosmic dust particles

Laboratory tests with simulated micrometeoroids to measure the heat transfer coefficient are discussed. Equations for ablation path length for electrically accelerated micrometeoroids entering a gas target are developed which yield guidelines for the laboratory measurement of the heat transfer coefficient. Test results are presented for lanthanum hexaboride (LaB sub 6) microparticles in air, argon, and oxygen targets. The tests indicate the heat transfer coefficient has a value of approximately 0.9 at 30 km/sec, and that it increases to approximately unity at 50 km/sec and above. Test results extend to over 100 km/sec. Results are also given for two types of small particle detectors. A solid state capacitor type detector was tested from 0.61 km/sec to 50 km/sec. An impact ionization type detector was tested from 1.0 to 150 km/sec using LaB sub 6 microparticles.

Roy, N. L.↗
NASA NTRS1975

A source for hyperbolic cosmic dust particles

Earlier analyses of the Pioneer 8 and 9 experimental meteoroid data have shown that the detectors on these two spacecraft are intercepting meteoroids with hyperbolic orbital parameters. It is shown in this paper that these results are entirely consistent with and, indeed, to be expected from other observations of the interplanetary meteoroid complex. Collisional breakup of meteoroids and post-collision radiation pressure modification of their orbits is found to be a sufficient cause for the observed results. Details of the calculations as well as of the results are presented.

Zook, H. A.↗
NASA NTRS1975

Collections of cosmic dust

Some recent results of collection experiments in the upper atmosphere by rocket techniques, by balloon collections in the intermediate atmosphere, and by recoverable satellites in near-earth space are described. Evidence is presented for the existence of relatively high and variable fluxes of submicron particles entering the atmosphere. These submicron-particle collections are consistent with implications from zodiacal light studies, provided the particles have a solar origin and are drifting outward with a constant radial velocity. A simple estimate suggests that these particles, by virtue of their refractory nature, can survive ejection from the sun near sunspots.

Hemenway, C. L.↗
NASA NTRS1978

Laboratory analogues to cosmic dust

Results are reported for a study of the condensation of a number of solids that are likely candidates for dust formed in astronomical environments. The condensate materials were produced by vaporizing a portion of a solid target of chosen composition by a laser pulse in an atmosphere of H2, O2, or Ar at 1 atm pressure. The systems studied include olivine, pyroxene, Fe-Ni alloy, Al2O3, carbon, CaCO3, SiC, Au-olivine powders, and Au-Al2O3 powders. Possible relations among the sizes, chainlike structures, and chemistries of the condensates and of grains formed in astronomical systems are investigated. The results indicate that the laser evaporation technique is useful for providing a wide variety of grain systems that are analogous to astronomical grain systems and that the grain materials produced are useful for spectral studies of materials believed to exist in astronomical environments, both as single materials and as multicomponent grain systems

Stephens, J. R.↗
NASA NTRS1981

The radiation-induced rotation of cosmic dust particles: A feasibility study

A crossed beam, horizontal optical trap, used to achieve laser levitation of particles in an effort to determine how solar radiation produces high spin rate in interplanetary dust particles, is described. It is suggested that random variations in albedo and geometry give rise to a nonzero effective torque when the influence of a unidrectional source of radiaton (due to the Sun) over the surface of a interplanetary dust particle is averaged. This resultant nonzero torque is characterized by an asymmetry factor which is the ratio of the effective moment arm to the maximum linear dimension of the body and is estimated to be 5 X 10 to the minus four power. It is hoped that this symmetry factor, which stabilizes the nonstatistical response of the particle, can be measured in a future Spacelab experiment.

Misconi, N. Y.↗
NASA NTRS1985

Polarized polymer films as electronic pulse detectors of cosmic dust particles

A new type of dust particle detector has been developed which consists of a polarized film of polyvinylidene fluoride (PVDF) having conducting electrons on its surface and operating with no bias voltage. Here, the response characteristics of PVDF detectors with areas in the range 4-150 sq cm and thickness in the range 2-28 microns to iron particles accelerated to velocities in the range 1-12 km/s are reported. The discussion also covers the mechanism of detection, fast pulse response, noise characteristics, and the dependence of the detector signal amplitude on particle mass and velocity. The detectors exhibit long-term stability and can be operated for extended periods of time over the temperature range -50 to +50 C; their response to dust particle impacts is unaffected by high background fluxes of charged particles.

Simpson, J. A.↗
NASA NTRS1986

The use of tethered satellites for the collection of cosmic dust and the sampling of man made orbital debris far from the space station

The use of a tethered subsatellite employed downward into the earth's upper atmosphere to an altitude of about 110 km above the earth would eliminate the orbital contamination problem while at the same time affording a measure of atmospheric braking to reduce the velocities of many particles to where they may be captured intact or nearly so with properly designed collectors. The same technique could also be used to monitor the flux of all types of man-made orbital debris out to a distance of more than a hundred kilometers in any direction from the space station. In this way the build up of any debris belt orbiting earth could be determined. The actual collecting elements used for both purposes could be of several different materials and designs so as to optimize the collection of different types of particles with different densities. Stacks of foils, films, plastics, and foams, as well as simple capture cells would be mounted in clusters around the outside of a tethered satellite and protected by iris covers until the tethered had been fully deployed. If the orientation history of the satellite were known the direction of the incoming material could be infered. A chief advantage in deploying such tethered collectors from the Space Station instead of from the shuttle is the ability to maintain deployment of the tether for days instead of hours resulting in much greater yields of intact particles and impact debris.

Corso, G. J.↗
NASA NTRS1986

Cosmic dust detection with large surface piezoceramics

Piezoelectric transducers mounted on targets made out of metal plates or plastic foils have been used in many former space missions to detect impacting dust particles and to determine some of their parameters (e.g., momentum). The proposed detector is based on a large disc made out of piezoceramic material. Dust particles impacting on the detector will cause electrical charge pulses due to the piezoelectric nature of the target material. These charge pulses are measured on the electrodes of the disc and transformed with a charge sensitive amplifier (CSA) to voltage pulses. Counting the number of pulses leads to the dust-flux impacting on the detector. Additionally the amplitude and the rise time of the pulse slopes are determinated to evaluate the momentum and the size of the dust particles. Due to the high charge production rate per force unit of piezoceramics and momentum transfer without loss the sensivity of this acoustic sensor is very high. A method to derive size and momentum from the rising slope of an acoustic signal is described.

Weishaupt, U.↗
NASA NTRS1986

Cosmic dust and space debris; Proceedings of the Topical Meetings and Workshop 6 of the 26th COSPAR Plenary Meeting, Toulouse, France, June 30-July 11, 1986

These proceedings encompass topics in the fields of extraterrestrial material samples, IRAS solar system and dust model results, and earth orbit debris. Attention is given to chemical fractionation during high velocity impact, particle deceleration and survival in multiple thin foil targets, and IRAS studies of asteroids, comets, cometary tails, the zodiacal background, and the three-dimensional modeling of interplanetary dust. Also discussed are the evolution of an earth orbit debris cloud, orbital debris due to future space activities, collision probabilities in geosynchronous orbits, and a bitelescopic survey of low altitude orbital debris.

Mcdonnell, J. A. M.↗
NASA NTRS1991

Cosmic dust particle densities - Evidence for two populations of stony micrometeorites

The existence of two populations of stony micrometeorites of distinctly different densities would result in significantly different orbital evolution properties for particles from each group. The densities inferred from deceleration of meteors in the earth's atmosphere suggest a substantial amount of the meteoric material has densities of 1 g/cu cm or less (Verniani, 1973). However, measurements of microcraters on lunar rock surfaces led Brownlee et al. (1973) to the conclusion that most micrometeoroids impacting the moon had densities in the 2-4 g/cu cm range, and low-density micrometeoroids were rare. The recovery of stony micrometeorites from the earth's stratosphere after atmospheric deceleration provides the opportunity to resolve the discrepancies. Here, the densities of 12 stony micrometeorites are determined, using synchrotron X-ray fluorescence to infer the particle mass and optical microscope measurements of the volumes. The particles fall into two distinct density groups, with mean values of 0.6 and 1.9 g/cu cm. The factor of 3 difference in the mean densities between the two populations implies differences in the orbital evolution time scales.

Flynn, G. J.↗
NASA NTRS1991

Intact capture of cosmic dust

The focus of this development effort is to capture dust particles at hypervelocities intact and unmelted in order to preserve volatile organics. At the same time, the capture process must minimize any organic elemental or compound contamination to prevent any compromise of exobiological analyses. Inorganic silicate aerogel has been developed as a successful capture medium to satisfy both requirements of intact capture and minimal organic contamination. Up to 6 km/s, silicate projectiles from a few microns up to 100 microns have been captured intact without any melting and with minimal loss of mass. Carbon in silicate aerogel can be reduced to less than 1 part in 1000 and hydrogen 3 parts in 1000 when baked in air. Under controlled inert gas environments, additional hydrocarbon reduction can be achieved.

Tsou, P.↗
NASA NTRS1992

Cosmic dust analogue material condensation in microgravity: The Stardust programme - First results and future activities

Initial results are presented from airborne experiments investigating the vapor phase condensation in microgravity, carried out in the framework of the Stardust international program. Special attention is given to the design and operation of the experimental equipment, which includes the furnace for producing vapors from different materials and the cloud chamber in which the vapor nucleation occurs. A two-part mathematical model was developed to describe the transport processes in the nucleation chamber. Results obtained from three experimental series were conducted with Mg and Zn aboard NASA's KC-135 reduced-gravity research aircraft showed that nucleation front (smoke cloud) was quite different in appearance in microgravity from that typically observed at 1-g condition. The Mg and Zn particles exhibited significant differences in shape; there was some evidence of coagulation.

Ferguson, F.↗
NASA NTRS1992

Cosmic dust

Dust is a ubiquitous component of our galaxy and the solar system. The collection and analysis of extraterrestrial dust particles is important to exobiology because it provides information about the sources of biogenically significant elements and compounds that accumulated in distant regions of the solar nebula and that were later accreted on the planets. The topics discussed include the following: general properties of interplanetary dust; the carbonaceous component of interplanetary dust particles; and the presence of an interstellar component.

Brownlee, Donald E.↗
NASA NTRS1992

Stardust: Studies in microgravity of condensation and agglomeration of cosmic dust analogue

A short description of the program Stardust whose goal is to study the formation and properties of high temperature particles and gases, including silicate and carbonaceous materials, that are of interest in astrophysics and planetary science, is given. The international program was carried out in microgravity conditions in parabolic flight. A description of the laboratory equipment, conceived to perform experimental tests in reduced gravity conditions, and which is based on the gas evaporation technique, is given. The gas evaporation technique utilizes one or more heated crucible to vaporize solids materials (SiO, Mg) in a low pressure of inert or reactive gas inside of a vacuum bell jar. The vapor pressures of the materials are controlled by the temperature of the crucibles. The temperature and pressure of inert gas are also controlled. By varying the vapor pressure relative to the gas temperature and pressure, the conditions for substantial grain condensation can be controlled and grain formation measured using light scattering techniques. Thus the partial pressure for grain condensation, can be measured as a function of temperature. The gas evaporation technique has the advantage that complex chemical systems can be studied by using multiple crucibles each containing solid source material. Experimental results and future trends are addressed.

Ferguson, F.↗
NASA NTRS1993

Stardust - Aggregation of cosmic dust analogues in microgravity

The condensation behavior of refractory grains near stars was investigated in an experiment which used a specially designed apparatus flown aboard NASA's Reduced Gravity aircraft. The apparatus consisted of a furnace in which a solid material (Zn or Mg) is vaporized into a temperature- and pressure-controlled chamber. Light scattered from the grains was recorded using a video system, and temperature measurements in the chamber were recorded throughout the microgravity period. The video and the temperature data are compared to models that predict the time dependence of the temperature- and vapor-pressure profiles to deduce the condensation behavior of the material. The joint U.S.-Italian program (named Stardust) for these experiments, designed to study refractory grain formation and aggregation, was set up to develop experimental and computational techniques for condensation studies under microgravity conditions.

Dell'aversana, P.↗
NASA NTRS1993

Helium-3 from the mantle - Primordial signal or cosmic dust?

Helium-3 in hotspot magmas has been used as unambiguous evidence for the existence of a primordial, undegassed reservoir deep in the Earth's mantle. However, a large amount of helium-3 is delivered to the Earth's surface by interplanetary dust particles (IDPs). Recycling of deep-sea sediments containing these particles to the mantle, and eventual incorporation in magma, can explain the high helium-3/helium-4 ratios of hotspot magmas. Basalts with high helium-3/helium-4 ratios may represent degassing of helium introduced by ancient (probably 1.5 to 2.0 billion years old) pelagic sediments rather than degassing of primordial lower mantle material brought to the surface in plumes. Influx of IDPs can also explain the neon and siderophile compositions of mantle samples.

Anderson, Don L.↗