Проведено исследование энергетически малозатратных баллистических траекторий перелета космического аппарата к Венере с попутным пролетом астероидов. Показано, что при использовании схем, включающих гравитационный маневр, требуемый для доставки посадочного аппарата в заданный район на поверхности Венеры, возможен пролет хотя бы одного астероида. Всего было обнаружено 39 астероидов, пролет которых может быть осуществлен при старте в 2029–2050 гг. Проведен анализ достижимых районов посадки при перелете космического аппарата к Венере по траекториям данного типа. Показано, что в каждое из окон старта в период с 2029 по 2050 гг. можно найти астероид, пролет которого оказывается возможным в период времени между двумя сближениями космического аппарата с Венерой.

We have studied energy-low-cost ballistic trajectories of a spacecraft flight to Venus with asteroid flyby. It is shown that when using schemes including a gravitational maneuver required to deliver the lander to a given area on the surface of Venus, the passing of at least one asteroid is possible. A total of 39 asteroids were discovered, whose passage can occur when launching in 2029–2050. An analysis of the attainable landing areas during the flight of a spacecraft to Venus along trajectories of this type has been performed. It is shown that in each launch window in the period from 2029 to 2050, it is possible to find an asteroid whose passage is possible during the time period between two approaches of the spacecraft to Venus.

In the framework of the project "Venera-D" a problem of landing the descent module in a given area of the surface of Venus is considered. With the standard approach to selection of the launch window and with limitations on the value of the re-entry angle into the atmosphere, as well as on the maximum allowable overload for lander during descent, a significant part of the planet’s surface is inaccessible for landing. The simplest way to expand the landing area could be to increase the launch window by moderate reducing the payload mass. However, the potential for such an increase is significantly limited, primarily by the required characteristic velocity cost. In this study a new approach is proposed to ensure landing of the descent module at any point on the surface of Venus. The basis of the proposed approach is the use of the gravitational field of the planet to transfer the spacecraft to the heliocentric orbit, resonant at a ratio of 1:1 with the orbit of Venus, and the subsequent return to its original position in one Venusian year, when another part of the surface will be available for landing. In the presented paper it is shown that application of new approach allows to provide radical expansion of achievable landing areas, and also to provide access to any point on the surface of Venus due to increase of duration of flight and small increase of characteristic velocity costs

The paper considers the problem of determining accessible landing areas on the surface of Venus and the possibility of expanding them by extending the launch windows in the period from 2026 to 2031, taking into account the constraints on the payload mass and the maximum overload level acting on the lander during descent in the Venusian atmosphere. We used the Venera-D planned mission requirements as the initial data set for our studies. The possibility of reaching the planet on the first and second half-orbits of the heliocentric Earth-Venus transfer orbits was explored. It was confirmed that through the extension of the launch window for 2031 it is possible to broaden the reachable landing areas. The cost of such expanding landing area in terms of payload is presented.

The SRG observatory, equipped with the X-ray telescopes Mikhail Pavlinsky ART-XC and eROSITA, was launched by Roscosmos to the L2 point on July 13, 2019. The launch was carried out from Baikonur by a Proton-M rocket with a DM-03 upper stage. The German telescope eROSITA was installed on SRG under agreement between Roskosmos and DLR. In December 2019, SRG started to scan the celestial sphere in order to obtain X-ray maps of the entire sky in several energy bands (from 0.3 to 8 keV, eROSITA, and from 4 to 30 keV, ART-XC). By mid-December 2020, the second full-sky scan had been completed. Over 4 years, 8 independent maps of the sky will be obtained. Their sum will reveal more than three million quasars and over one hundred thousand galaxy clusters and groups. The availability of 8 sky maps will enable monitoring of long-term variability (every six months) of a huge number of extragalactic and Galactic X-ray sources, including hundreds of thousands of stars. Rotation of the satellite around the axis directed toward the Sun with a period of 4 hours makes it possible to track faster variability of bright X-ray sources. The chosen scanning strategy leads to the formation of deep survey zones near both ecliptic poles. We present sky maps obtained by the telescopes aboard SRG during the first scan of the sky and a number of results of deep observations performed during the flight to L2, demonstrating the capabilities of the Observatory in imaging, spectroscopy and timing. In December 2023 the Observatory will switch for at least two years to observations of the most interesting sources in the sky in triaxial orientation mode and deep scanning of selected fields with an area of up to 150 sq. deg. These modes of operation were tested during the Performance Verification phase. Every day, SRG data are dumped onto the largest antennae of the Russian Deep Space Network in Bear Lakes and near Ussuriysk.

We consider the concept of applying gravity assist maneuvers near Venus using resonant orbits with a period equal to the Venusian one. We show that the proposed operations based on this concept allow the reachable landing areas on the surface of Venus to be expanded radically. The price of this approach is an increase of the time interval needed to solve this problem by a value equal to the orbital period of Venus. The cost of the characteristic velocity in this case remains within limits close to the standard variants of planning missions to Venus.

The paper considers the problem of finding accessible areas on the Venus surface and the prospect of their increasing by extension of launch windows during the period from 2026 to 2031; taking into account the restrictions on the payload weight and the maximum overload level affecting the lander during the descent in the Venus atmosphere. The project of the Venera-D mission is used as the initial data for the work. The possibility of reaching the planet on the first and second half-turns of the heliocentric transfer orbit is analyzed. As an example, the effect of the launch window expansion for 2031 on the nature of changes in the accessible landing areas is considered. Possible payload weight expenses for launch window expansion are estimated. The launch windows are selected by solving the Lambert problem, where the transit spacecraft momentum near the Earth for the flight to Venus along the first and second half-orbit paths at the period from 2026 to 2042 is calculated. The accessible landing area is shown when increasing the launch windows initially adopted for 2031.The estimation of payload weight expenses for increasing the launch windows is performed.

The Spectrum–Röntgen–Gamma (SRG) space observatory was launched from Baikonur on July 13, 2019, and is currently on a flight trajectory in the vicinity of the collinear Sun–Earth libration point L2. The planned service life of the observatory is 7 years and includes an all-sky survey and in-depth studies of individual objects in the X-ray range 0.3–15 keV. We consider the technical limitations of the mission pertaining to the launch scenario, the spacecraft design and system characteristics, including the data and command transmission, orbital motion and attitude control systems, and the peculiarities of the ground segment used to accomplish these tasks. The flywheel offloading strategy for the attitude control system is analyzed within the mentioned limitations. The goal of this analysis is to determine an optimal balance between the flywheel offloading operations while controlling the attitude of the observatory, the orbital maneuvers to keep it on a given trajectory, propellant consumption, and the requirements from the scientific measurements. The proposed method allows the total propellant consumption to be minimized by coordinated control of the operation of the system of attitude control rocket engines while simultaneously using them to maintain the specified orbital parameters.

The Spectrum-Roentgen-Gamma (SRG) project is intended for surveying the entire sky in the X‑ray band using two telescopes mounted onboard the spacecraft of the same name (SRG). In addition, some specially chosen areas of the sky and some radiation sources are planned to be investigated after the completion of the survey. The spacecraft was planned to be launched in 2018 into the vicinity of solar-terrestrial collinear libration point L2, using the Proton-M launch vehicle with a DM-03 block upper stage. The technology for completely surveying the celestial sphere consists in scanning by rotating the parallel axes of telescopes around the spacecraft axis, which roughly followed the direction to the Sun. The measurement data, stored onboard the spacecraft, would then be transmitted to the ground receiving stations using the mean gain antenna, the axis of which coincided with the spacecraft’s axis of rotation. This imposed some constraints on the mission design. These constraints included the permissible amplitude of the trajectory of spacecraft motion relative to the libration point in the direction orthogonal to the Sun–Earth line. In addition, the consumption of the onboard propellant was allowed only for orbit correction needed for keeping the spacecraft near the libration point. In this connection, a method was developed using the upper stage in order to decrease the mentioned amplitude down to acceptable values, in the conditions of the requirements imposed on the unit. The paper presents an assessment of its effectiveness.

The paper focuses on a future mission to Venus, Venera-D, which is presently at the stage of defining the scientific objectives and shaping the preliminary mission architecture. The main scientific goals regarding the atmosphere, magnetosphere and internal structure of Venus are considered. The current configuration, baseline, and additional elements of the mission are described.

The article describes the trajectory scenario for the Venera-D mission. The main aspects of optimal launch dates are considered. A scenario, which enables insertion of an orbiter into a highly elliptical orbit and a lander on the surface of Venus is described. Characteristics of the choice for operational orbit and scenario ensuring scientific data transfer from the lander on the surface of Venus to the Earth are justified. In addition, possibilities of transfer of a small satellite to the vicinity of the collinear Lagrangian point of the Sun-Venus system, and also a subsatellite into the orbit of the main orbiter, are considered.

Spectrum–Röntgen–Gamma (SRG) is a space observatory designed to observe astrophysical objects in the X-ray range of the electromagnetic spectrum. SRG is planned to be launched in 2019 by a Proton-M launch vehicle with a DM3 upper stage. The spacecraft will be delivered to an orbit around the Sun–Earth collinear libration point L2 located at a distance of ~1.5 million km from the Earth. Although the SRG launch scheme has already been determined at present, in this paper we consider an alternative spacecraft transfer scenario using a lunar gravity-assist maneuver. The proposed scenario allows a oneimpulse transfer from a low Earth orbit to a small-amplitude orbit around the libration point to be performed while fulfilling the technical constraints and the scientific requirements of the mission.