Synthesis of a combined system for precise stabilization of the Spektr-UF observatory: II

The paper presents the second part of the results of search studies for the development of a combined system of high-precision stabilization of the optical telescope for the designed Spectr-UF international observatory [1]. A new modification of the strict method of the synthesis of nonlinear discrete-continuous stabilization systems with uncertainties is described, which is based on the minimization of the guaranteed accuracy estimate calculated using vector Lyapunov functions. Using this method, the synthesis of the feedback parameters in the mode of precise inertial stabilization of the optical telescope axis is performed taking the design nonrigidity, quantization of signals over time and level, and errors of orientation meters, as well as the errors and limitation of control moments of executive engine-flywheels into account. The results of numerical experiments that demonstrate the quality of the synthesized system are presented.     

Disturbance of the upper atmosphere after crash launch of the <Emphasis Type="Italic">Proton</Emphasis> carrier rocket

The data of inclined sounding obtained on July 5, 1999 after explosion of the Proton carrier launcher in the upper atmosphere are discussed. A comparative analysis is performed of the detected disturbances with disturbances recorded during explosion of the Soyuz rocket in the middle atmosphere and with disturbances typical for the standard mode of the rocket flight.     

The application of space imagery to geology and mineral exploration in the USSR — A case history

A short history of the application of space images to geology and mineral exploration in the U.S.S.R. is given with special emphasis to circular features observed on small scale and low-resolution pictures within the Precambrian terrain. These features are believed to correspond to the oldest basins of volcano-sedimentary deposition or, in other words, to primary cells of basic proto-crust. Metallogenic significance of circular features is also discussed. Remote sensing in oil-gas field exploration and in the study of recent tectonics are also dealt with.     

Synthesis of a combined system for precise stabilization of the Spektr UF observatory. I

The paper presents the first part of results of basic research for development of a combined system of high-precision stabilization of the optical telescope for the international observatory Speckr UF (currently under design) planned to study emission of stars in the UV waveband. A new direct method used in these studies for calculating program controls is described. The results of numerical experiments are presented.     

ASAR imaging for coastal upwelling in the Baltic Sea

Analysis of Envisat Advanced Synthetic Aperture Radar (ASAR) and Aqua/Terra Moderate Imaging Spectrometer (MODIS) infrared (IR) imagery of coastal upwelling in the southeastern Baltic Sea is presented. It is found that upwelling features are well distinct in the SAR images, and the leading imaging mechanism appears to be the change of the marine atmospheric boundary layer (MABL) stratification over the sea surface temperature (SST) front. This finding is supported by model calculations of the MABL transformation supplemented with the SAR backscatter calculations based on the CMOD4 model. In addition an empirical dependence of the SAR contrasts over the upwelling region on the wind speed and the SST drop is suggested. Finally, surface slicks accumulated in the sea surface current convergence zones generate additional distinct features in SAR imagery. This effect is interpreted within the framework of the coastal current circulation model based on analysis of the SST snapshot.     

Standing Alfvén waves with m ≫ 1 in a dipole magnetosphere with moving plasma and aurorae

The structure of standing Alfvén waves with large azimuthal wave numbers (m ? 1) is studied in a dipole model of the magnetosphere with rotating plasma. In the direction across magnetic shells the structure of such waves is determined by their dispersion associated with curvature of geomagnetic field lines and corresponds to the travelling wave localized between toroidal and poloidal resonant surfaces. In projection into the ionosphere (along geomagnetic field lines) this structure is similar to the structure of a discrete auroral arc. The azimuthal structure of an auroral arc is similar to azimuthal structure of Alfvén waves with m ∼ 100. Possible interaction mechanisms between the Alfvén waves and energetic electron fluxes forming auroral arcs are discussed.     

Impact of microwave discharges on the lower ionosphere and middle atmosphere

The behaviour of the lower ionosphere and middle atmosphere during microwave discharges at 30 – 60 km altitude is investigated. The developed plasmachemical model includes 166 processes for 19 minor neutral (including excited) components and for 13 charged species. The distinctive differences of this model from previous investigations are (1) the equation system is closed assuming undisturbed conditions, (2) the inclusion of additional reactions involving hydrogen components, and (3) considerable improvement of the reaction scheme for ionized components. The results are analyzed in three main aspects: the behavior of the minor neutral and excited components, variations of charged species including the electron concentration, and finally possible influence of the air heating on the plasma chemistry.