Engineering topics

Basilevsky, A. T.

Publications and source records attributed to Basilevsky, A. T..

23 records · Page 2

NASA NTRS1993

Preliminary Stratigraphic Basis for Geologic Mapping of Venus

The age relations between geologic formations have been studied at 36 1000x1000 km areas centered at the dark paraboloid craters. The geologic setting in all these sites could be characterized using only 16 types of features and terrains (units). These units form a basic stratigraphic sequence (from older to younger: (1) Tessera (Tt); (2-3) Densely fractured terrains associated with coronae (COdf) and in the form of remnants among plains (Pdf); (4) Fractured and ridged plains (Pfr); (5) Plains with wrinkle ridges (Pwr); (6-7) Smooth and lobate plains (Ps/Pl); and (8) Rift-associated fractures (Fra). The stratigraphic position of the other units is determined by their relation with the units of the basic sequence: (9) Ridge bells (RB), contemporary with Pfr; (10-11) Ridges of coronae and arachnoids annuli (COar/Aar), contemporary with wrinkle ridges of Pwr; (12) Fractures of coronae annuli (COaf) disrupt Pwr and Ps/Pl; (13) Fractures (F) disrupt Pwr or younger units; (14) Craters with associated dark paraboloids (Cdp), which are on top of all volcanic and tectonic units except the youngest episodes of rift-associated fracturing and volcanism; (15-16) Surficial streaks (Ss) and surficial patches (Sp) are approximately contemporary with Cdp. These units may be used as a tentative basis for the geologic mapping of Venus including VMAP. This mapping should test the stratigraphy and answer the question of whether this stratigraphic sequence corresponds to geologic events which were generally synchronous all around the planet or whether the sequence is simply a typical sequence of events which occurred in different places at diffferent times.

Basilevsky, A. T.↗

NASA NTRS1992

Geochemical aspect of impact cratering: Studies in Vernadsky Institute

Studies of the geochemical effects of impact cratering at the Vernadsky Institute in collaboration with the Institute of Dynamics of Geospheres, Moscow State University, Leningrad State University, and some other institutions were fulfilled by several approaches. At the initial stage, three approaches were used: (1) experimental studies of high-temperature vaporization of geological materials (basalts, granites, and so on) in vacuum that was considered as a model of behavior of impact melt and vapor; (2) search of impact-induced geochemical effects in the rock from terrestrial impact craters; and (3) studies of samples of lunar regolith. The next stage of the studies included experiments on quasi-equilibrium vaporization of geological material in Knudsen cells. The results of this investigation are discussed.

Yakovlev, O. I.↗

NASA NTRS1992

The geology of the Venera/Vega landing sites

We have performed a photogeological analysis of the Venera Vega landing sites using Magellan radar images. These seven sites are the only places on Venus where geochemistry measurements were taken. In this study, the updated coordinates of the landing sites are used and the landing circle has a radius with an admissible error of about 150 km.

Basilevsky, A. T.↗

NASA NTRS1992

Largest impact craters on Venus

High-resolution radar images from the Magellan spacecraft have allowed us to perform a detailed study on 25 large impact craters on Venus with diameters from 70 to 280 km. The dimension of these large craters is comparable with the characteristic thickness of the venusian lithosphere and the atmospheric scale height. Some physical parameters for the largest impact craters on Venus (LICV), such as depth, ring/diameter ratio, and range of ballistic ejecta deposits, have been obtained from the SAR images and the altimetry dataset produced by MIT. Data related to each of these parameters is discussed.

Ivanov, B. A.↗

NASA NTRS1992

Low-emissivity impact craters on Venus

An analysis of 144 impact craters on Venus has shown that 11 of these have floors with average emissivities lower than 0.8. The remaining craters have emissivities between 0.8 and 0.9, independent of the specific backscatter cross section of the crater floors. These 144 impact craters were chosen from a possible 164 craters with diameters greater than 30 km as identified by researchers for 89 percent of the surface of Venus. We have only looked at craters below 6053.5 km altitude because a mineralogical change causes high reflectivity/low emissivity above the altitude. We have also excluded all craters with diameters smaller than 30 km because the emissivity footprint at periapsis is 16 x 24 km and becomes larger at the poles.

Weitz, C. M.↗