Russian program of planetary missions

In the area of Solar System Exploration most of recently proposed mission oriented to the studies of Mars. Except MARS-96 and possibly MARS SAMPLE RETURN missions other Mars missions use Molnija class launchers. All Russian missions heavily involve international partners.     

Quasilinear relaxation of pickup interstellar ions

The quasilinear relaxation of pickup interstellar helium ions is described in the diffusion shell approximation. It is shown that the Cherenkov damping of Alfvén waves due to their refraction in the nonuniform solar wind could inhibit the complete relaxation of pickup helium ions over the bispherical shell.     

Magnetopause stability threshold for patchy reconnection

This review is devoted to the problem of the internal fine structure of the Earth's magnetopause. A number of theoretical and experimental papers dealing with this subject is discussed from a unified viewpoint. The Vlasov kinetic approach is used to study the stability of magnetopause magnetic surfaces that can be destructed by the growth and overlapping of magnetic islands. The stochastic wandering of magnetic field lines between the destructed surfaces can result in magnetic percolation, i.e. the appearance of a topological connection of interplanetary and geomagnetic field lines. Such a process may be considered as a mechanism of the macroscopic (but spatially localized) reconnection. We discuss this in relation with the phenomena of spontaneous patchy reconnection, recently observed at ISEE satellites and now known as flux transfer events.Drift tearing mode, which is responsible for the growth of magnetic islands can be stabilized due to its coupling with ion sound waves, and the process of percolation will be interrupted if even a thin region with smooth stable magnetic surfaces exists within the magnetopause. Accordingly, we obtain a magnetopause stability threshold for localized reconnection. It is represented in the form of dependence of marginal dimensionless thickness of the magnetopause on the angle of magnetic field rotation within it.Further, we discuss the possible role of lower hybrid turbulence permanently observed within the. magnetopause and speeding up the process of reconnection. Nonlinear calculations supporting the developed model are given in the appendices. We consider briefly the motion of reconnecting flux tubes and evaluate the time necessary for the accomplishment of percolation. The calculations show that the appearance of reconnection patchies at the dayside magnetopause cannot occur too far from the stagnation region. The latter agrees with experimental indications on the most probable site of the formation of flux transfer events. In the concluding part of the review we discuss the necessary limitations on the theory, possible lines of its future advance and comparison with the experimental data.     

Dust hazard near Halley Comet in case of the VEGA project

The motion of dust particles near Halley Comet is studied and the probability of dust impacts with the spacecraft in case of the VEGA (Venus-Halley)- project is determined. The formation of a crater due to a particle impact with the dust shield is considered and the necessity for using a dual-sheet bumper shield is substantiated. The thickness of a front sheet that plays a role of the particle evaporator is estimated theoretically. The numerical experiment is carried out that simulates the dynamics of collision and evaporation of a particle. Three factors causing perforations of the rear sheet are discussed, i.e. dust penetrated through holes in the front sheet, gas jets and spall fragments of the front-sheet. The consideration of these factors makes it possible to estimate basic parameters of the dual-sheet bumper shield. Flexural vibrations of the front sheet under action of the reverse gaseous jet from the rear sheet are discussed that can affect essentially the shield strength. The perturbing effect of the dust and gas fluxes on the spacecraft is studied.     

Mars glob: Creation of an international network of Mars surface landers

Program MARS GLOB provides step-by-step deployment of an international network of Mars surface stations by association the MESUR NETWORK (USA), INTERMARS-NET (ESA) programs with the network of small stations and penetrators now under developing in Russia jointly with international cooperation in frameworks of the MARS-96 Project. It is offering also delivery on Mars surface two penetrators and Mars Rover. Now penetrators and Rover are developing by Russia with participation of other countries in frameworks of the MARS-98 (or MARS TOUR) Project.     

Plasma processes within the magnetosphere boundaries

A brief summary is presented of recent progress in estimating the rates of energy, momentum and mass transport of the solar wind through the magnetopause in terms of an analysis of the non-linear stage of various plasma instabilities. It is shown that the energy supply to the Earth's magnetosphere is due to reconnection on the dayside magnetopause and its dissipation during magnetospheric substorms, being controlled by both the interplanetary field parameters and by the dynamic pressure of the solar wind.     

Injection mechanism for cosmic ray acceleration

The quasilinear theory of MHD waves excitation by cosmic rays accelerated at a front of supernova shock has been constructed. It is shown that the energetic particles excite the waves propagating from the shock front, the intensity and the spectrum of these waves is obtained. The role of nonlinear Landau damping in the formation of such spectrum has been analysed. The diffusive scattering length of the high energy particles in the preshock region has been calculated and it is shown with the help of these formulae that the effective Fermi acceleration at the shock front is possible upto the values of the relativistic factor = 10⁴ - 10⁵. The injection mechanism for cosmic rays acceleration has been proposed. It is based on stochastic Fermi acceleration of the thermal plasma by MHD waves excited in the preshock region. Different possibilities for wave phase velocity dispersion needed for stochastic Fermi acceleration are analysed, those are the excitation of the oblique magnetosonic waves as well as the excitation of parallel Alfven waves propagating in opposite directions. The distribution function of the suprathermal particles accelerated by MHD waves is obtained, the cosmic rays density as well as the lower boundary of their energy spectrum realised in the proposed mechanism are also calculated.     

Solar wind interaction with comet Halley

In March 6 and 9, 1986 the spacecrafts ‘Vega-1’ and ‘Vega-2’ have flown through the coma of comet Halley and have carried measurements of plasma, energetic particles, magnetic field and plasma waves along its trajectory. A short review of these measurements and its comparison with theoretical models of solar wind interaction with comets are given.

The spacecrafts ‘Vega-1’ and ‘Vega-2’ have studied the solar wind loading by cometary ions, the structure of cometary bow shock and the processes in the inner coma of comet Halley. Exactly in this sequence we discuss the results of measurements and compare them with the theory.