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Calculations of ionization-excitation source rates in gaseous media irradiated by fission fragments and alpha particles
Dissociative excitation of CO(a 3 Pi) and other metastable fragments such as O(5S) produced by electron impact on CO2
Olivine accumulation in Apollo rock 12040 and basaltic fragments, using textural and microprobe analyses
Noritic and anorthositic rock fragment proportions and sources in Apollo 12 soil samples
Apollo 11 and 12 devitrified glass fragments temperature histories indicating broad range of subsolidus crystallization temperatures
Visible and near IR spectral reflectivity measurements of basalt separates, glass and anorthositic fragments from Apollo 12 mare samples
The dissociative excitation of CO (a 3Pi) and other metastable fragments produced by electron impact on CO2 has been investigated from threshold to 50 eV. The observed threshold for CO (a 3Pi) production at 11.9 (plus or minus 0.5) eV was near the minimum required energy of 11.5 eV.
Three small fragments of Luna 16 basalt (NASA sample designation G38) have been analyzed with an electron microprobe. The mineralogy is generally similar to that found in Apollo 11 and 12 igneous rocks: major amounts of clinopyroxene, plagioclase, ilmenite and olivine; accessory spinel, troilite, Fe metal and residual phases. Unlike some Apollo 12 basalts, there is continuous zoning with no composition gap in the G38 spinels. Plagioclase analyses follow the same nonstoichiometric trends previously found in Apollo 11 and 12. The samples indicate a magmatic history (rapid crystallization from reduced melts) similar to that inferred from studies of Apollo 11 and 12 basalts.
The Ar40-Ar39 gas retention age and the Ar38-Ar37 cosmic ray exposure age have been determined on a total rock sample of the basalt fragment B-1 returned from Mare Fecunditatis by the Luna 16 mission. This sample shows a large low-temperature loss of radiogenic Ar40 but defines a reasonably good high-temperature plateau at 3.45 plus or minus 0.04 b.y. This is presumed to identify the period of igneous activity in Mare Fecunditatis. This activity is found to be later than that in the area of Mare Tranquilitatis, but earlier than that in the area of Oceanus Procellarum and Mare Imbrium. The cosmic-ray exposure age was found to be 475 m.y.
A photographic study of a simulated tank fragmentation test was made. Sixteen disks and four spheres were ejected from a test article mounted in a vertical orientation 110 ft above a target installed on the test chamber floor. The test was performed at a chamber pressure of 25 microns. Velocities at impingement on the target ranged from 88 to 120 ft/sec; corresponding ejection velocities at the exit plane of the ejector assembly ranged from 29 to 87 ft/sec. Tumble axes of the disks were expected to be all in the north-south direction; the majority of those measured were, while some were skewed from this direction, the maximum observed being 90 deg. A typical measured tumble rate was 2.4 turns/sec. The dispersion pattern measured on the target was reasonably regular, and measured approximately 16 ft east-to-west by 11 ft north-to-south.
The compositional data obtained are combined with existing data from larger rock samples and compared with bulk analyses of soils to determine compositional ranges and dominant igneous rock types present in the regolith and breccias. Criteria are presented for the recognition of three types of igneous fragments in a limited sample of Apollo 14 material. Explanations for the differences between glass and rock compositions are discussed.
One hundred seventy-six oxide mineral grains in the Luna 20 samples were analyzed by electron microprobe. Spinel is the most abundant oxide, occurring in troctolite fragments. Next most abundant is ilmenite, which occurs in all rock types except those containing spinel. Chromite also occurs in all rock types except those containing spinel. Minor amounts of ulvospinel, armalcolite, zirkelite, baddeleyite and an unidentified TiO2-rich phase were also found. Spinel grains are predominantly spinel-hercynite solid solutions, commonly with very minor chromite. The Fe/(Fe + Mg) ratio is generally lower than in spinel from Apollo 14 rocks. Chromites in non-mare rocks are similar to those from mare rocks. Ilmenite of mare origin is Mg-poor and Zr-rich compared to non-mare ilmenite; these elements may therefore be useful in determining the origin of ilmenite grains. Phase equilibria considerations suggest that spinel troctolite crystallized from a melt high in alumina; a likely candidate is the high-alumina basalt of Prinz et al. (1973).
Only fine-grained rocks are present in the Luna 20 samples, and coarser-grained rocks are represented by fragments of single crystals. A petrologic study has been made of 47 fine-grained crystalline rocks, microbreccias, and glassy aggregates. In addition, a total of 33 single crystals of pyroxene, plagioclase, olivine, and spinel, in the size range from 125 to 500 microns, have been examined using electron microprobe and single-crystal X-ray diffraction techniques. The most abundant fine-grained crystalline rocks in the samples examined are recrystallized anorthositic norite and anorthositic troctolite. Gabbroic rocks, anorthosite, and KREEP basalt are present but not common. Most of the single crystals of pyroxene and plagioclase could have been derived from coarser-grained noritic, troctolitic, and anorthositic rocks. However, three of the 14 pyroxene crystals, and two of the five olivine crystals have Fe/(Fe + Mg) contents greater than 0.45 and are believed to have been derived from mare basalts or related rocks.
Two milligrams of less than 125-micron size particles from the Luna 20 soil sample (22001,17) have been examined. The results of the mineral identification and analysis verify earlier assumptions that the nature of the lunar highlands is predominantly anorthositic in composition. The presence of highly magnesian clinopyroxene, orthopyroxene, and olivine suggests crystallization of highland rocks in an ultrabasic environment. No fragments were observed that could be unequivocally assigned to mare basalt types.
The petrology of Luna 20 lithic fragments is described and compared to that of other highland sites. An identification of the major types of rocks that compose the lunar terrae is attempted, and their probable petrogenesis is discussed.
The rate of production of new fragmental lunar surface material is derived theoretically on the hypothesis that such material is excavated from a bedrock layer by meteoroid impacts. An overlaying regolith effectively shields the bedrock layer from small impacts, reducing the production rate of centimeter-sized and smaller blocks by a large factor. Logarithmic production rate curves for centimeter to motor-sized blocks are nonlinear for any regolith from centimeters to tens of meters in thickness, with small blocks relatively much less frequent for thicker (older) regoliths, suggesting the possibility of a statistical reverse bedding. Modest variations in the exponents of scaling laws for crater depth-diameter ratio and maximum block-diameter to crater diameter ratio are shown to have significant effects on the production rates. The production rate increases slowly with increasing size of the largest crater affecting the region.
Automatic rifle was modified for remote, single-shot use. To simulate statistically--determined fragment size from rocket-motor casing blunt-nosed bullet was made of same alloy. Cartridge was loaded with enough powder to make bullet reach target at same estimated velocity as shrapnel from rocket casing.
The effect of disturbed air behind the meteor body on the motion and ablation of fragments observed partly as the difference between the photometrically and the dynamically determined masses of the meteor body. By use of extreme mathematical conditions, this difference can be made to reach orders of magnitude during the latter part of the trajectory.