Precipitating Protons and Their Role in Ionization of the Polar Ionosphere

Spatial distributions of the electron density in the latitude range 60°–90° N were calculated on the basis of a physical model of the E and lower Fregions of the high-latitude ionosphere using statistical models of auroral proton and electron precipitation. It is shown that precipitating protons can play the key role in the ionization of the Eregion in the dusk and midnight sectors of the auroral oval. However, quantitative estimates of the contribution of protons to the ionization depend on the used statistical models of electron precipitation. Comparison of the electron density profiles calculated for two incoherent scatter radars, EISCAT (Tromsö) and ESR (Svalbard), for simultaneous precipitation of electrons and protons and for electron precipitation only show that the influence of protons is the most significant in the dusk sector over the EISCAT radar and in the midnight sector over the ESR radar. The results presented indicate the need to take protons into account when radar data are used to derive precipitating electron spectra.     

Airglow in the Visible and Infrared Spectral Ranges of the Disturbed Upper Atmosphere under Conditions of High-Velocity Plasma Jet Injection: I. Experimental data

The measurements of infrared emission from an artificial structure, which was generated during the Fluxus experiment with plasma jet injection into the atmosphere, are obtained and discussed for the first time. Additional experimental data on the airglow in the visible spectral band of the disturbed region of the atmosphere are presented. A generalized analysis of the data is given.     

Blood and small intestine cell kinetics under radiation exposures: Mathematical modeling

Mathematical models which describe the dynamics of two vital body systems (hematopoiesis and small intestinal epithelium) in mammals exposed to acute and chronic radiation are developed. These models, based on conventional biological theories, are implemented as systems of nonlinear differential equations. Their variables and constant parameters have clear biological meaning, that provides successful identification and verification of the models in hand. It is shown that the predictions of the models qualitatively and quantitatively agree with the respective experimental data for small laboratory animals (mice, rats) exposed to acute/chronic irradiation in wide ranges of doses and dose rates. The explanation of a number of radiobiological effects, including those of the low-level long-term exposures, is proposed proceeding from the modeling results. All this bears witness to the validity of employment of the developed models, after a proper identification, in investigation and prediction of radiation effects on the hematopoietic and small intestinal epithelium systems in various mammalian species, including humans. In particular, the models can be used for estimating effects of irradiation on astronauts in the long-term space missions, such as Lunar colonies and Mars voyages.     

Life-span of irradiated mammals. Mathematical modelling

A mathematical model of the mortality dynamics of irradiated mammals is developed. It relates the statistical biometrical functions with the statistical and kinetical characteristics of the critical systems in the organism. This model can be used for predicting the life shortening of irradiated mammals.     

Theoretical solution for the lift force of “ecranoplan” moving near rigid surface

This paper develops a theoretical solution for the problem of determining thin wing's lift force while moving near flat surface (a screen). The solution is determined under the assumption of fluid being ideal and incompressible. The Chaplygin–Zhukovsky hypothesis of rear-edge-limited solution is taken into consideration. The solution of a problem is reduced to the Fredholm equation that is solved numerically. The generalization of the Zhukovski solution was obtained, which provides the lift force dependence on the altitude of the flight. The behavior of the lift force is very peculiar: it increases on decreasing altitude above the rigid surface. The screen effect becomes essential on moving wing altitude being smaller than the wing's length. The effect was detected experimentally before and gave birth to construction of a special flying vehicle named “ecranoplan”. It is shown in the paper that the lift force could increase several orders of magnitude. This effect could be used in developing flying vehicles of high loading capacity, which could be used in the territories of smooth surface: savannas, steppes, deserts, lakes, swamps, etc. The effect could be used for developing vehicles for operation on other planets having not very dense atmosphere and relatively smooth surface (like Mars). Flights in such an atmosphere are energy consuming, while using the effect of lift force increase near the surface could be very effective.     

Luminescence of the disturbed upper atmosphere in the visible and infrared spectral ranges in the conditions of injection of a high-velocity plasma jet: II. Theoretical interpretation of the luminescence in the visible spectral range

A theoretical interpretation is given to the experimental data on the luminescence in the visible spectral region of the disturbed upper atmosphere in the conditions of injection of a high-velocity aluminum plasma jet (the “Fluxus” experiment). Mathematical models of optical effects are presented. It is demonstrated that the results of the calculations and the experimental data agree satisfactorily. The principal physical and chemical processes responsible for the observed luminescence are determined.     

Mathematical model for assessment of radiation risk on long space missions.

A mathematical model is developed which describes the dynamics of radiation-induced mortality in mammalian populations. It relates statistical biometric functions with statistical characteristics and dynamics of an organism's critical system. In the framework of the model the effects of low and very low dose rates of chronic radiation on mice are simulated. Respectively, thrombocytopoietic and granulocytopoietic systems are considered as the critical ones. To calculate the dynamics of these systems, mathematical models are applied, too. In accordance with experimental data, the mortality model reproduces on quantitative level both increased and decreased mortality rates in populations of LAF1 mice, which were chronically exposed, respectively, to low and very low level radiation. All this makes it feasible to use the model as a basis for risk assessments of low level long-term irradiation.     

Fluid flow interaction with an obstacle near free surface

The two-dimensional problem of thin obstacle interaction with compressible fluid flow near free surface under microgravity was regarded. The fluid was assumed occupying infinite semi-space, gravity was neglected as compared with fluid inertia. The obtained exact solution shows that for relatively thin layer the resistance force does not depend on the layer thickness, but depend on body length and inclination angle, and surpasses twice the respective values for the infinite medium, which could be explained by additional wave resistance arising in the presence of free surface.