Effect on Surface Thermal Properties of Calibrated Exposure to Micrometeoroid Environment
Reproduction of metal surface exposure to hypervelocity impact by micron-size particles
TARGET SIMULATION↗
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Ionization probability of iron particles at meteoritic velocities
Ion production for ablation of micron size iron particles moving at supersonic speed in air and argon
AIR↗
Effects of impingement of rocket exhaust gases and solid particles on a spacecraft Interim report, Mar. 18 - Oct. 25, 1966
Impingement damage to spacecraft from rocket exhaust gases and micron sized metal particles
IMPINGEMENT↗
Ionization probability of iron particles at meteoric velocities.
Meteoritic ion pair production probability by total ablation of micron-size Fe particles in air and Ar as function of particle velocity
PARTICLE CHARGING↗
Cosmic dust in the stratosphere.
Cosmic dust in one to 100 micron size range in stratosphere, noting balloon-borne collecting technique and upper limit on total terrestrial accretion rate
Arnold, J. R.↗
Fog modification with giant hygroscopic nuclei.
Visibility improvement in warm fog by seeding with micron size hygroscopic particles, noting results for NaCl
Jiusto, J. E.↗
Comments on the paper by D. G. Rea and B. T. O'Leary, ''On the composition of the Venus clouds.''
Critique of paper on water crystal existence on Venus, presenting arguments against existence of clouds of micron sized ice crystals
Cheyney, H.↗
Particle cloud impingement damage
Single impact data considered ineffective in estimating target damage induced by micron-sized particle cloud impingement
Laderman, A. J.↗
Miniature grinder for solid specimens
Machine grinds fines to appropriate micron sizes with the least biological trauma and greatest degree of reproducibility. Device controls destruction of material so that recovery of microorganisms is as great as possible and protects operation and grinding products from exogenous contamination.
Houser, C. P.↗
Venus Clouds: A dirty hydrochloric acid model
The spectral and polarization data for Venus are consistent with micron-sized, aerosol cloud particles of hydrochloric acid containing soluble and insoluble iron compounds, whose source could be volcanic or crustal dust. The ultraviolet features could arise from variations in the Fe-HCl concentration in the cloud particles.
Hapke, B.↗
Experimental investigation to simulate propellant heating in the nuclear light bulb engine.
Experiments to heat a simulated propellant to high bulk temperatures by the absorption of thermal radiation are discussed. Argon seeded with micron-sized carbon particles was used as the simulated propellant; a 500 kw d-c arc was used as the radiant energy source. Bulk temperatures up to 3860 K were obtained with greater than 95% of the incident radiation absorbed. The arc radiation source, seed dispersal equipment, techniques used to prevent transparent wall coating by the seeds, and calorimetric measurement of bulk temperature are also discussed.
Klein, J. F.↗
Petrology of basaltic and monomineralic soil fragments from the Sea of Fertility.
Basaltic and monomineralic fragments from the 150-425 micron size fractions of the Luna 16 core obtained from the Sea of Fertility were studied by optical petrographic, electron microprobe, and single-crystal X-ray diffraction techniques. Three textural varieties were identified in the basalts (intersertal, subophitic, and recrystallized). These textures, the assemblages, and individual mineral compositions (especially pyroxenes) indicate that these basalts crystallized under conditions very similar to those from Apollo 11. The pyroxenes have slightly lower Ti/Al (atomic) ratios than the Apollo 11 pyroxenes. We interpret the presence of octahedral Al as being due to the low TiO2/Al2O3 (weight %) ratio in the bulk rock. All observations made on the fine-grained basalt fragments are consistent with a rapid, near-surface, one-stage crystallization history.
Bence, A. E.↗
Extreme radiation damage in soil from Mare Fecunditatis.
High-voltage electron microscopy has been used to compare radiation effects in micron-size soil grains from the Luna 16 site (Mare Fecunditatis) and the four Apollo landing sites. Radiation damage by heavy solar particles is strikingly greater in the Luna 16 sample than in the other four samples. It is suggested that less movement of the soil at Mare Fecunditatis has taken place, perhaps because of its proximity to the limb and consequent lower exposure to energetic electrons in the earth's magnetospheric tail, which would cause electrostatic agitation of fine particles.
Phakey, P. P.↗
On circumstellar molecules in the Pleiades.
Consideration of both old and new observations of the interstellar 4232-A line of CH(+) for the brightest members of the Pleiades. These observations suggest that the molecules are circumstellar in some sense, perhaps resembling in this respect the micron-sized grains inferred to be present in this region.
Hobbs, L. M.↗
Observations on degradation of UV systems on Nimbus spacecraft
Broad band photometer experiments in the 1200 to 3000 A have been operating on Nimbus 3 and 4 since April 1969 for the purpose of determining the nature of variations in the UV solar irradiance. An Ebert-Fastie double monochromator has been measuring the solar irradiance and earth radiance from 2500 to 3400 A for the determination of global atmospheric ozone distributions since April 1970. From prelaunch testing and an evaluation of the flight data it is concluded that the principal source of degradation is probably the spacecraft. The degradation produces a characteristic signal loss and change in angular response of the system which might be explained by micron sized droplets becoming a permanent residue under the influence of solar UV radiation.
Heath, D. F.↗
Major element composition of Luna 20 glasses.
Ten per cent of the 50 to 150-micron size fraction of Luna 20 soil is glass. A random suite of 270 of these glasses has been analyzed by electron microprobe techniques. The major glass type forms a strong cluster around a mean value corresponding to Highland basalt (anorthositic gabbro) with 70% normative feldspar. Minor glass groups have the compositions of mare basalts and of low-K Fra Mauro type basalts. The glass data indicate that Highland basalt is the major rock type in the highlands north of Mare Fecunditatis.
Warner, J.↗
Radiation effects in soils from five lunar missions.
Optical and high-voltage electron microscopy were used to study radiation-produced defects. There is no systematic decrease in solar flare track distributions in lunar fines even to a depth of 2.5 m. The soil gradually accumulates in thickness; stirring by impacts is usually on a small scale. The accumulation rate at Luna 16 site is far lower than at the Apollo sites; the mean track density in micron-size grains there exceeds one trillion per sq cm; more than 90% of those grains are metamict; the Luna 16 site is at high longitude where electrostatic charging and transport of soil by geomagnetic tail electrons are minimal. A large fraction of soil grains on sloping ground have been isotropically irradiated, suggesting a tumbling downhill motion.-
Phakey, P. P.↗
Dislocation generation during early stage sintering.
Discussion of the effects of capillarity-induced stresses on dislocations during early stage sintering. A special version of Hirth's (1963) theoretical calculation procedures modified to describe dislocation nucleation on planes meeting the sintering body's neck surface obliquely is shown to predict plastic flow at stress levels know to exist between micron size metal particles in the early stages of sintering.
Sheehan, J. E.↗