Volume 63, Nº 3 (2025)

The paper presents measurement data obtained in the space experiment “Shielding Composite” by thermoluminescent and solid-state track detectors. A cylindrical container made of a composite shielding material based on fluoroplastic (1 cm thick, density 4.05 g/cm³) was installed in the left cabin of the International Space Station (ISS) Service Module. The measurement data were obtained for the period from February 21 to September 19, 2022, which falls at the growth phase of the solar activity cycle. The shielding effect of the composite material was determined as the ratio of doses received outside and inside the container, and according to measured data, it was 1.33 ± 0.08 for the absorbed dose and 1.29 ± 0.07 for the dose equivalent. This effect is mainly due to a decrease in the contribution to the dose from the Earth's radiation belts, which corresponds to the results of calculations carried out by the ray tracing method for the detector locations.

Transfers in the central Newtonian field to the geostationary orbit are considered under the assumption that low thrust becomes zero when spacecraft with solar panels enters the Earth’s shadow. Using the maximum principle, the two-point boundary value problem is formed. It includes the conditions for optimal intersection of the shadow boundaries, the so called jump conditions in conjugate variables. Then the influence of jump conditions on the two-point boundary value problem solutions is investigated. Calculations for the flights of spacecraft with initial mass 5550 kg and thrust 0.55 N (initial acceleration 0.1 mm/s²) from the initial orbit with inclination 13° and the height of perigee 9.2 Mm and of apogee 76.8 Mm were done. They showed that if the argument of pericenter is equal to 0° and the longitude of the ascending node Ω₀ = 180°, the difference in the propellant cost for two trajectories – with or without taking into account the jump conditions – does not exceed 0.15 % (in comparison with “nominal” trajectories, i.e., transfers without zeroing the thrust), and may be less than 0.01 % for some values of initial time. For other values of Ω₀, the difference may be greater than 30 %. It was discovered also that the two-point boundary value problem may have several solutions. They differ from each other by the set of orbits crossing the Earth’s shadow.

This paper considers the idea of reducing near-Earth space debris by releasing the spent additional fuel tank (AFT) and the booster's central block (CB) into the Earth's atmosphere. The spacecraft transfer from a reference circular orbit of an artificial Earth satellite to a target elliptical orbit is optimized. The transition maneuvers are carried out using a booster with a high limited-thrust engine and the AFT. The second zonal harmonic of the Earth's gravitational field is taken into account. A simplified model of spacecraft control is considered: the direction of the thrust vector on each of the active segments are determined by two angles that depend linearly on time.

The article presents the results of a study of the deep factors influence on the spatial and temporal patterns of the the ice cover formation of the Arctic shelf cryolithozone. The main source of ice information is satellite remote sensing data, which are necessary to solve scientific and practical problems of the Northern Sea Route development. The paper presents a comparative analysis of data from satellite monitoring of the ice cover thickness with petrophysical Earth's crust sections and lithospheric magnetic anomalies measured on the CHAMP satellite. To identify the structural features of the lithosphere that affect the formation of the ice cover, petrophysical sections crossing the zones of accelerated ice melting were constructed: density–based on gravity anomalies, magnetic–based on anomalies of the Earth's magnetic field module. In the zones of potential accumulation of gas hydrates in the Arctic seas of the Northern Sea Route, channels of endogenous fluid-dynamic factor influence have been identified. This made it possible to make a forecast of the areas of occurrence of deep origin emergencies caused by the mantle fluid flows migration. Based on the analysis of deep petrophysical sections in the zones of gas hydrate development near the Northern Sea Transport Magistral, the authors have identified through taliks at the thermofluid channels output. In areas of the Laptev Sea, where, according to geochemical studies, methane emissions of deep genesis have been confirmed, the sub-vertical trajectories of fluid flows approaching the seafloor from a depth of 25-30 km have been traced in deep sections. During the work the work, an assessment was made of the most likely location of endogenous natural hazards in areas of gas hydrates accumulation and in areas with a high level of bottom sediments gas saturation in the Barents, Kara, East Siberian, Chukchi Seas and the Laptev Sea. The study of the influence of the fluid-dynamic factor on the Northern Sea Transport Corridor ice regime will optimize the choice of the safest transport and logistics routes for uninterrupted year-round navigation.