Vol 53, No 6 (2019)

We have analyzed the spatial and age relationships of volcano-tectonic units that have developed on the surface of Venus: groove belts, coronae, and rift zones. Most of the coronae (60%) are spatially and stratigraphically associated with the groove belts. Those are mainly circular and calderic coronae. Some of the coronae (20%) are associated with the rift zones. Such coronae are classified as domal and are concentrated in the Beta–Atla–Themis (BAT) region. The spatial association of coronal structures with regional extension zones and predominance of extensional structures (grooves) in the corona rims suggests that these units also formed in extensional environments. The spacing of fractures (the distance between adjacent fractures) in the rims of both older and younger coronae has a typical value of 1.1 ± 0.4 km, which is approximately half the characteristic spacing of the structures of young rift zones (1.8 ± 0.4 km) and nearly coincides with the spacing of fractures in ancient groove belts (1.2 ± 0.3 km). We interpret the coincidence of the characteristic spacing of fractures in the corona rims and in the groove belts as a possible indication of an older age of the coronae, which coincides with the age of the formation of the groove belts.

This study is dedicated to the consideration of the relativistic effects (geodetic precession and nutation that make up the geodetic rotation) in the rotation of Mars and its satellites (Phobos and Deimos). The relativistic effects were calculated using the method developed in (Pashkevich, 2016), which is applicable to the study of any bodies of the Solar System that have long-term ephemerides. As a result, the most significant secular and periodic terms of the geodetic rotation in the perturbing terms of physical libration and in the Euler angles were determined for the Martian satellites for the first time.

For the purpose of mathematical simulations of the formation processes for planetesimals in the Solar protoplanetary disk, statistical thermodynamics for nonextensive fractal systems was developed and its properties were determined on the basis of the Rényi parametric entropy taking account of fractal conceptions on the properties of disperse dust aggregates in the disk medium. It has been found that there is a close relationship between the Rényi thermodynamics of nonextensive systems on the one hand and the technique for obtaining fractal and multifractal dimensions based on geometry and stochastics on the other. It has been shown that temporal evolution of a closed system to the equilibrium state depends on a sign of the deformation parameter that is a measure of nonextensivity of a fractal system. Different scenarios for constructing fractal dimensions of various orders for fractals and multifractals are discussed and their properties are analyzed. The approach developed allows the evolution of cosmologic and cosmogonic objects, from galaxies and gas−dust astrophysical disks to cosmic dust, to be modeled on the basis of the generalized thermodynamics with fractional derivatives and the thermodynamics for fractal media. A specific feature of these objects is remoteness and globality of force interactions between the system elements, a hierarchical pattern (usually, multifractality) of the geometric and phase spaces, a significant range of spatial−temporal correlations, and the prevalence of asymptotic power-law statistical distributions.

In the context of the circular restricted three-body problem (RTBP), the search for the spacecraft’s asymptotic velocity \({{V}_{\infty }}\) for gravity assist maneuvers (GMs) can be performed using the Jacobi integral \(J\) and the main property of the Jacobi integral constant for GMs, \({\text{const}} = J \approx 3 - V_{\infty }^{2}.\) It is shown in the paper that the standard cumbersome way of traditional derivation of this property that is used in modern astrodynamics can be significantly simplified.