Vol 57, No 4 (2023)

The Lonar crater (India) is the best preserved and most studied on Earth, formed in basalts, which makes it possible to conduct a comparative study with impact transformations of mineral matter on the Moon and other planets of the Solar System. Comparative studies have shown that impactor material, both on the Earth and on the Moon, is present in impactites not only in a geochemically dispersed form, as previously thought, but also in the form of individual submicron particles distributed in the molten target material. These are particles of native nickel, taenite, and high-nickel kamacite, which, apparently, are the transformed material of the impactor. High-nickel submicron metal inclusions are widespread in the impactites of the Lonar crater, as they were found in all studied preparations made from materials collected from different points along the rim of the crater. The high-nickel particles found in this study are an additional argument in favor of the previously stated assumption about the chondrite type of impactor.

Temperature and pressure sensors, which are part of the ExoMars-2022 landing platform (LP) meteorological complex, are designed to measure the main parameters of the Martian atmosphere: temperature, pressure, and vertical component of wind speed. Temperature and pressure measurements begin during the descent, after the separation of the lower hemisphere, when the height above the surface will be from 2.1 to 8.5 km, depending on the descent trajectory. Above, before opening the parachute, the vertical profile of the atmosphere can be obtained using the accelerometer block, which is also part of the meteorological complex. After landing, a long-term monitoring of the near-surface layer of the atmosphere is carried out. Measurements are taken at different heights from the surface. Taking into account the measurement of the vertical component of the wind after landing, the local surface-to-atmosphere heat flux is calculated. The measurements make it possible to obtain the dynamics of the interaction between the atmosphere and the surface. In the paper we considered the scientific problems solved by the sensors, briefly described the measurement program and described in detail the sensors and their characteristics

The lidar device as part of the meteorological complex of the ExoMars-2022 landing platform is designed to study Martian aerosol, the planetary boundary layer, and small-scale atmospheric turbulence. A miniature lidar based on a pulsed semiconductor laser and an avalanche photodiode in the photon counting mode will make it possible to obtain aerosol backscattering profiles along a vertical path from 10 to 1500 m during the day and from 15 to 10000 m at night. In the passive mode, the sky brightness is measured in a narrow spectral range and in a narrow solid angle with a frequency of up to hundreds of hertz. The measured fluctuations can provide information about the turbulence of the daytime atmosphere and its relation to dust activity. In the paper we considered the scientific tasks of the experiment, the program of measurements on the surface of Mars and described in detail the components of the equipment and the features of their work.

The stability of the secular orbital dynamics of a number of potentially existing satellites of exoplanets has been analyzed. The secular dynamics of possible satellites (“exomoons”) of the planets KOI-268.01, Kepler-1000b, and Kepler-1442b have been found to be stable. The possible values of the exomoon orbital parameters for these systems have been estimated. The dynamics of the satellites discovered around the planets Kepler-1625b and Kepler-1708b from the analysis of observations are considered. It has been found that the semimajor axis of the orbit of the moon of the planet Kepler-1625b can range from 5 to 25 planetary radii. It has been shown that the solution available for the satellites of the planet Kepler-1708b (Kipping et al., 2022) corresponds to a stable orbit of the satellites.

The concept of Alfvén waves, introduced into science 80 years ago, played an important role in the formation and development of cosmic electrodynamics. Alfvén waves differ in that at each point in space the group velocity vector and the vector of the external magnetic field are collinear to each other, due to which the waves can carry momentum, energy, and information over long distances. In memory of the outstanding event, we briefly describe two Alfvén resonators, one of which is located high above the Earth, in the radiation belt, and the second, in the ionospheric layers. Both resonators have a discrete spectrum in the upper part of the range of ultralow frequency oscillations of natural origin (approximately from 0.2 Hz to 7 Hz). The close connection between the concept of Alfvén waves and the current problems of the electrodynamics of geophysical media is especially emphasized.