Venus Interior Structure and Dynamics

No two rocky bodies offer a better laboratory for exploring the conditions controlling interior dynamics than Venus and Earth. Their similarities in size, density, distance from the sun, and young surfaces would suggest comparable interior dynamics. Although the two planets exhibit some of the same processes, Venus lacks Earth’s dominant process for losing heat and cycling volatiles between the interior and the surface and atmosphere: plate tectonics. One commonality is the size and number of mantle plume features which are inferred to be active today and arise at the core mantle boundary. Such mantle plumes require heat loss from the core, yet Venus lacks a measurable interior dynamo. There is evidence for plume-induced subduction on Venus, but no apparent mosaic of moving plates. Absent plate tectonics, one essential question for interior dynamics is how did Venus obtain its young resurfacing age? Via catastrophic or equilibrium processes? Related questions are how does it lose heat via past periods of plate tectonics, has it always had a stagnant lid, or might it have an entirely different mode of heat loss? Although there has been no mission dedicated to surface and interior processes since the Magellan mission in 1990, near infrared surface emissivity data that provides information on the iron content of the surface mineralogy was obtained fortuitously from Venus Express. These data imply both the presence of continental-like crust, and thus formation in the presence of water, and recent volcanism at mantle hotspots. In addition, the study of interior dynamics for both Earth and exoplanets has led to new insights on the conditions required to initiate subduction and develop plate tectonics, including the possible role of high temperature lithosphere, and a renewed drive to reveal why Venus and Earth differ. Here we review current data that constrains the interior dynamics of Venus, new insights into its interior dynamics, and the data needed to resolve key questions.     

Origin of Molecular Oxygen in Comets: Current Knowledge and Perspectives

The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument onboard the Rosetta spacecraft has measured molecular oxygen (O₂) in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) in surprisingly high abundances. These measurements mark the first unequivocal detection of O₂ in a cometary environment. The large relative abundance of O₂ in 67P/C-G despite its high reactivity and low interstellar abundance poses a puzzle for its origin in comet 67P/C-G, and potentially other comets. Since its detection, there have been a number of hypotheses put forward to explain the production and origin of O₂ in the comet. These hypotheses cover a wide range of possibilities from various in situ production mechanisms to protosolar nebula and primordial origins. Here, we review the O₂ formation mechanisms from the literature, and provide a comprehensive summary of the current state of knowledge of the sources and origin of cometary O₂.     

Dynamic behavior of wing leading edge assembly with thermal protection coating

The paper presents an approximate solution of a problem on dynamic behavior of a wing leading edge assembly discretely reinforced by a system of ribs and coated with thermal protection coating.     

Flight duration,potential and relative efficiency of an electric multicopter

In this paper, it is proposed the flight duration to be assessed by the potential value and the helicopter number. The data on the available power and the relative efficiency for a number of multicopter models are provided.     

On similarity criteria in flight mechanics

With the aim of enhancing the simulation of flow processes and dynamics of aircraft motion, the analysis of the appropriate equations and search for new similarity criteria are carried out. New relations are obtained for the equations of aircraft motion allowing for experiments with overweight models under certain conditions.     

Synthesis of control laws for aircraft lateral motion at the lack of data on the slip angle: Analytical solution

The problem of lateral motion stabilization is analytically solved for the fourth-order model of aircraft motion using the method of output signal control synthesis that is based on the control object decomposition. Numerical simulation data are presented.     

Coupled CFD/CSD simulation of the helicopter main rotor in high-speed forward flight

The helicopter main rotor in forward flight is considered in this paper. The results for rigid blades and elastic blades are compared by the method of coupled simulation. The influence of the structural damping coefficient on the blade in-flight deformation is also considered.     

Application of a discrete-continuous model of strength analysis to solve the identification problem of a thermally loaded structure

This paper proposes to solve the problem of determining the strength properties of materials for thin-walled structural elements under mechanical and thermal loading as an optimization problem. A mathematical statement of the problem under certain assumptions is given.     

Drop test simulation for a helicopter tail landing gear

The paper describes a mathematical model of drop tests on the landing gear of the Ka-62 helicopter. The model is formulated using the multibody system simulation procedure based on the Lagrange equations of the first kind.     

A technique for numerical modeling of liquid film disintegration in the pneumatic injector of aircraft engines

A technique for calculating the two-phase flows in the pneumatic injector of the aircraft engine is developed based on solving the model problem, namely, on verification of the two-phase flow model by means of solving the problem of liquid column disintegration under the effect of an incident airflow. We determine the turbulence models that satisfactorily describe the biphase flow processes.