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Radar observations of Toro were made with a (one-dimensional) resolution of 0.005 arc sec. When radar and optical data are combined, they suggest an irregular rocky surface slightly smoothed by a mantle of loose material.
The orbital evolution of (1685) Toro has been investigated over 5000 yr. The asteroid exhibits a locked resonance through an 8:5 commensurability with the earth for the first 3400 yr of integration and a locked resonance with Venus through a 13:5 commensurability for the last 1000 yr. Control of these resonances passes from the earth to Venus as the distance from the earth's orbit gets greater and the distance to Venus' orbit gets closer as a consequence of the precession of the argument of perihelion. The double resonance may give Toro the ability to avoid collisions with the earth and Venus at the present time but this is still uncertain. Mars perturbations could remove Toro from the deepest part of the resonance in about 3,000,000 yrs.
Average data for igneous and/or metaigneous rocks and soils from seven lunar sites are presented. There are compositional similarities between Apollo 11 and Luna 16 eastern maria, Ap 12 and 15 western maria, and between Ap 16 and L 20 highlands. Subtle differences do exist between the paired mare sites and the two highland sites and striking differences between the eastern and western maria. Chondritic normalized REE (rare earth element) patterns for igneous rocks and soils from all sites range from 7-350 generally with negative Eu anomalies. Anorthositic gabbroes to anorthosites, presumably highland material, exhibit a positive Eu anomaly. The REE patterns or Sr isotopic ratios suggest two lava flows each for the L 16 and Ap 14 sites, at least four lava flows for the Ap 11 and 12 site and about six for the Ap 15 site.
A flight evaluation of an ambient air sample pressurization system was conducted at altitudes between 6 and 12 km. The system regulated the sample pressure to 10.15 + or - 0.1 N/sq n and provided sample flow to three gas analysis instruments included in the system. Ozone concentrations measured by two instruments employing different techniques varied from about 30 parts per billion by volume (ppbv) to over 350 ppbv, and the two ozone monitors agreed to within 20 ppbv. A carbon dioxide analyzer indicated modifications required for future installations.
Gehrels (1967), investigating the direction of Vesta's pole, found that his light curves exhibited two distinct maxima. An analysis of all available light curves over the period from 1950 to 1973 shows that Vesta has a true period of 10h40m58s.84 (+ or - 0s.01 p.e.) with two maxima and two minima. Vesta's rotation is direct. The shape is that of a spheroid, with one diameter exceeding the other two by roughly 15%, and with an apparent shape irregularity near the south pole.-
Analysis of the light curves and color-phase and polarization-phase relations of Geographos according to observations over an eight-month period in 1969. The light curves are relatively smooth with two distinct maxima and minima. The largest amplitude of 2.03 mag is the largest observed on asteroids to date. The average B-V is 0.87 and the average U-B is 0.50. A laboratory model that best reproduced Geographos' light curves was a cylinder having hemispherical ends with a length to width ratio of 2.7; on the basis of this model and a relation of Bowell and Zellner (1973), Geographos was calculated to be approximately 1.50 km wide and 4.0 km long.
A photoexcitation technique is suggested which is direct and convenient, requiring little special equipment. No change in the dimensions of the crystal sample is necessary. Although related to the technique of interposing a filter between the light source and the sample, it differs in that the filter is part of the crystal itself. Basically, one of the electrodes is split into two electrodes, one collecting charge from carriers excited in the bulk. This phenomenon in which the carriers follow very closely the electric field lines has been used in position-sensitive semiconductor radiation detectors (Norbeck and Carlson, 1963) but has not been applied to lifetime measurements. In a sense, the split electrode creates a sample without a surface.
Melilite and pyroxene were separated from a coarsely crystalline chondrule in the Allende meteorite and analyzed by microprobe and spark source mass spectrometer techniques. Elemental abundances in the bulk chondrule are consistent with a mixture of equal amounts of the two minerals, as observed microscopically. The lanthanide distributions are markedly different in the two minerals; relative to chondrite abundances, melilite shows progressive depletion of the lanthanides La-Sm, a positive Eu anomaly, and relatively constant abundances of the heavier lanthanides (Gd-Yb, and Y) whereas pyroxene shows progressive enrichment towards the heavier lanthanides, on which is superimposed a negative Eu anomaly. Both minerals, and the bulk chondrule, show unusual concentrations of the platinum metals, but the crystallographic site or sites of these metals remains to be determined.
Polarimetric observations of 43 asteroids are presented. All objects show a well-developed negative polarization branch as an indicator of unconsolidated surface regoliths. The empirical slope-albedo law for diffusely reflecting solid surfaces is reexamined and used to compute polarimetric albedos and diameters for 30 asteroids. In many cases the results are in good agreement with infrared-radiometric diameters; the older visual diameter measurements were systematically too small. Radiometric albedos below 5%, however, are not confirmed by the polarimetry. Bimodal frequency distributions are noted for asteroid color, albedo, and the depth of the negative polarization branch. Correlations between B - V color and polarimetric parameters suggest that most of the asteroid population can be divided into silicaceous and carbonaceous opacity classes.
An investigation is conducted of upper ionosphere molecular ion composition data, which because of the unexpected, abrupt enhancements sometimes exhibited at high latitudes, may indirectly offer additional clues to understanding the processes by which the lower atmosphere becomes perturbed. It is found that molecular ion irregularities are sometimes localized in a relatively narrow region of time and space. The abruptness of these events suggests that lower atmosphere energetic processes presumed responsible for the ion enhancements may also be narrowly distributed.
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Asteroids (6), (14), (39), and (51) were observed at the Leiden Southern Station. Only (39) Laetitia seems to show some variation in color (3% in visual-ultraviolet) correlated to the light curve. If a similar effect is present for (6) Hebe, it should only be present at small phase angles. The light curves of (14) Irene and (39) Laetitia show light variations of a few percent of the rotational period indicating probable surface macrostructure.
This paper is a brief survey of a portion of the research on trace constituents in the stratosphere and mesosphere between 1971 and 1974. A primary motivation for much of the stratospheric research came from the realization that man's activities may influence global climate and the atmospheric ozone content, our shield against certain UV wavelengths. A great deal of progress has been reported in understanding both the present background stratosphere and the responses to be expected from additions of nitrogen oxides, water, and chlorine oxides, especially with respect to ozone. Trace constituents in the mesosphere have been modeled and measured to increase our understanding of the physics and chemistry of the mesosphere but also to relate mesospheric composition and transport to ionospheric processes at higher altitudes, to D region ion chemistry, and to upper stratospheric composition.
The slow bend precracked Charpy fracture toughness and tensile behavior of arc-melted and hot-rolled Fe-12Ni alloys containing up to 4 atomic percent reactive metal additions were determined at -196 C and 25 C after water quenching from three annealing temperatures. The fracture toughness of Fe-12Ni at -196 C was improved by small amounts of Al, Ce, Hf, La, Nb, Ta, Ti, V, Y, and Zr, but not by Si. Cryogenic toughness was improved up to 7.5 times that of binary Fe-12Ni and varied with the reactive metal, its concentration, and the annealing temperature.
New photometric observations on the UBV system are presented for 45 asteroids, bringing the total to 91 for which complete UBV colors are available. The reduced magnitudes B (1, 0) scatter about the adopted catalog values by + or - 0m, 25, with negligible systematic difference. The UBV colors fall into three distinct groups which correspond almost perfectly to the S (silicaceous or stony), C (carbonaceous), and U (unclassifiable) asteroid types recently identified from polarimetry, infrared radiometry, and narrow-band spectrophotometry. It becomes possible to classify asteroids from UBV observations alone. The S asteroids have colors very similar to those of L and LL ordinary chondrites, and some of the U objects are consistent in color with nickel-iron or enstatite-rich meteorites, but no meteorites appear to have the UBV colors of the C asteroids. The asteroid C and S compositional types have no exact counterparts among the surfaces of natural satellites.
Results are reported for analyses of UBV photoelectric photometric data and light curves of the asteroid Laetitia. The pole orientation is determined using a technique for reducing the scatter in the magnitude-phase relation. No significant variations in color are found over the surface, and the light curves are found to indicate topographic elements (peaks, scarps, or depressions) approximately 10 km in radius. It is shown that the light-curve amplitudes as well as the wide scatter in observed magnitude and phase relation can be explained by a triaxial ellipsoidal figure with a dimensional ratio of about 15:9:5. It is concluded that the size, shape, and composition of this asteroid are highly suggestive of a major collisional fragment from a substantially more massive differentiated parent body.
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Polarimetric observations are presented and analyzed for a total of 94 asteroids. The data include numerical parameters describing the polarization-plane curve, the maximum depth of the negative branch, geometric albedo, and diameter. With few exceptions, the polarizations are found to be repeatable from hour to hour, night to night, and apparition to apparition at the same solar phase angle within an observational accuracy of plus or minus 0.05%. It is shown that over a range of more than a factor of 50 in diameter or a factor of 100,000 in mass, all the asteroids seem to have microscopically very rough or particulate surface textures. In terms of their polarimetric properties, the asteroids are classified as follows: 48 in the broad S class, with compositions corresponding to stony-iron meteorites or ordinary chondrites; 34 in the C class, probably corresponding to carbonaceous chondrites; three to five M asteroids with surfaces rich in free metal; two with low-opacity surfaces (class E) attributable to pure enstatite; and five of other types.