Volume 57, Nº 6 (2023)

In order to study the processes related to the origin and retention of water on the surface of the Moon, an experimental setup has been created at the Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences (GEOKHI RAS), for the analysis of (re)sublimation processes of water ice in a vacuum at low temperatures. The temperature range for (re)sublimation varies from –100 to 0°C. The setup is connected to an Isotope Ratio Mass Spectrometer (IRMS), which allows for measuring the isotopic composition of the vapor of the evaporating substance and providing an estimation of the (re)sublimation rate under specific physicochemical conditions. The direct introduction of gases into the mass spectrometer in real-time mode sets the developed setup apart from foreign counterparts. The setup is equipped with a transparent quartz window through which the surface of the studied substance can be heated using a halogen lamp, simulating the movement of solar rays on the surface of mineral grain compositions under conditions similar to those on the lunar surface. In addition to studying gas (de)sorption on the surfaces of mineral grains of various compositions, the setup can also be used for researching the (re)sublimation of gas hydrates and CO2.

A discussion is presented of the effects generated by the imbalance between the insolation energy of polar-day zones and the radiation energy of polar-night zones on multicentennial changes in the Earth’s climate. The dependence of this imbalance on the Earth’s orbital parameters is determined. The energy imbalance curves are compared with the known temperature curves for the polar regions, which have been estimated from the results of an analysis of ice cores taken in Antarctica and Greenland. The curves clearly reveal a difference between the contributions of cosmic and terrestrial factors to the temperature profiles for the regions in question and demonstrate a synchronicity of these factors. Algorithms are obtained for calculating the magnitude of fluctuations in the size of the Earth’s polar caps relative to their averages. The results obtained within the assumptions taken in this work enable predictions to be made about the development of the current global warming and about changes in the size of the Arctic and Antarctic polar caps. It is predicted that over the next three millennia, changes in the Earth’s orbital parameters will contribute to the slow melting of the northern polar cap. Then, the trend for a new growth of the northern polar cap will again manifest itself. In the Southern Hemisphere, a trend towards increased glaciation has already formed. Influenced by the cosmic factor, it will intensify over the next 20 000 years.

The paper discusses priority scientific tasks related to the study of small bodies in the Solar System, identifies the most promising objects for investigation from a spacecraft on a flyby trajectory and the sample return mission, and develops proposals for the preliminary composition of scientific instruments for remote asteroid research methods. A long-term and phased Russian scientific program for studying small Solar System bodies using spacecraft with electric propulsion has been proposed. The project is designed in such a way as to explore the largest number of scientifically interesting asteroids using a smaller number of spacecraft. A design concept for a small spacecraft to investigate near-Earth asteroids on a flyby trajectory and a main spacecraft for studying metallic asteroids in the Main Belt and sample sample return has been developed. A ballistic analysis of the flyby of five near-Earth asteroids and three metallic asteroids in the Main Belt is presented, as well as a ballistic analysis of the sample return mission from a Main Belt asteroid. The option of sample return using the nuclear tug Zevs is also considered.

Изучена дегазация вещества углистого хондрита Allende (тип СV3) на специально сконструированной для этих задач установке. Представлены результаты экспериментальных исследований по ступенчатому нагреву (без накопления газов) и изотермическому отжигу образцов метеорита с определением состава выделяемых газов методами газовой хроматографии в интервале температур от 200 до 800°C. Для учета сорбированной воды дополнительно изучена дегазация при 50 и 110°C. Получены КР- и ИК-спектры как первичного вещества Allende, так и вещества после его отжига при трех температурах: 200, 500 и 800°C. На их основе прослежен ход теплового преобразования вещества родительского тела метеорита и получена оценка максимальной температуры метаморфизма. Проведено сравнение с результатами дегазации углистого хондрита другого типа – Murchison (тип CM2).

The motion of planetesimals initially located in the feeding zone of the planet Proxima Centauri c, at distances of 500 AU from the star to the star’s Hill sphere radius of 1200 AU was considered. In the analyzed non-gaseous model, the primary ejection of planetesimals from most of the feeding zone of an almost formed planet c to distances greater than 500 AU from the star occurred during the first 10 million years. Only for planetesimals originally located at the edges of the planet’s feeding zone, the fraction of planetesimals that first reached 500 AU over the time greater than 10 million years was more than half. Some planetesimals could reach the outer part of the star’s Hill sphere over hundreds of millions of years. Approximately 90% of the planetesimals that first reached 500 AU from Proxima Centauri first reached 1200 AU from the star in less than 1 million years, given the current mass of the planet c. No more than 2% of planetesimals with aphelion orbital distances between 500 and 1200 AU followed such orbits for more than 10 million years (but less than a few tens of millions of years). With a planet mass equal to half the mass of the planet c, approximately 70–80% of planetesimals increased their maximum distances from the star from 500 to 1200 AU in less than 1 million years. For planetesimals that first reached 500 AU from the star under the current mass of the planet c, the fraction of planetesimals with orbital eccentricities greater than 1 was 0.05 and 0.1 for the initial eccentricities of their orbits eo = 0.02 and eo = 0.15, respectively. Among the planetesimals that first reached 1200 AU from the star, this fraction was approximately 0.3 for both eo values. The minimum eccentricity values for planetesimals that have reached 500 and 1200 AU from the star were 0.992 and 0.995, respectively. In the considered model, the disk of planetesimals in the outer part of the star’s Hill sphere was rather flat. Inclinations i of the orbits for more than 80% of the planetesimals that first reached 500 or 1200 AU from the star did not exceed 10°. With the current mass of the planet c, the percentage of such planetesimals with i > 20° did not exceed 1% in all calculation variants. The results may be of interest for understanding the motion of bodies in other exoplanetary systems, especially those with a single dominant planet. They can be used to provide the initial data for models of the evolution of the disk of bodies in the outer part of Proxima Centauri’s Hill sphere, which take into account gravitational interactions and collisions between bodies, as well as the influence of other stars. The strongly inclined orbits of bodies in the outer part of Proxima Centauri’s Hill sphere can primarily result from bodies that entered the Hill sphere from outside. The radius of Proxima Centauri’s Hill sphere is an order of magnitude smaller than the radius of the outer boundary of the Hills cloud in the Solar System and two orders of magnitude smaller than the radius of the Sun’s Hill sphere. Therefore, it is difficult to expect the existence of a similarly massive cloud around this star as the Oort cloud around the Sun.

Прогнозирование движения астероидов, сближающихся с Землей, (АСЗ) представляет собой комплексную задачу, требующую использования сложной техники, различных методик и больших вычислительных затрат. В последние десятилетия достигнут существенный прогресс в данной области, однако многие проблемы еще ожидают своего решения. В данной работе рассмотрены основные методы прогнозирования движения АСЗ, используемые на разных этапах, начиная c проведения наблюдений и заканчивая изучением таких особенностей движения, как тесные сближения и столкновения с планетами, орбитальные и вековые резонансы, хаотичность и предсказуемость движения. Статья основана на докладе, сделанном на научно-практической конференции с международным участием “Околоземная астрономия–2022” (18–21 апреля 2022 г., Москва).