April 26, 2022

Abstract:

An essential part of the projects to explore Venus using a lander is to determine attainable landing sites on its surface. First of all, such a task appears due to the inability to land anywhere on the surface, and the reason for this is the short duration of the launch window from the Earth (approximately 2 weeks including the optimal launch date), as well as restrictions on the maximum permissible overload. An additional factor reducing attainable landing areas of the mission is the low angular velocity of own rotation of Venus. This study suggests a new approach to extend the attainable landing areas. Its essence is to use the gravitational field of Venus to transfer the spacecraft to a heliocentric orbit resonant with the orbit of Venus in the ratio of periods 1:1.

The effectiveness of the proposed approach is shown at the example of the Venus-D project, which is scheduled to launch in 2029. A variant of the scenario with a launch in 2031 is also considered. Flight trajectory modeling was carried out, maps of the areas of the surface of Venus attainable for landing were constructed. Modeling is carried out within the framework of the patched conics method. The spatial gravity maneuver model is based on the "V∞ globe" model. It has been demonstrated that there is always at least one date within the launch window, the start on which allows landing at almost any point on the surface of Venus. It is shown that, in general, the application of the proposed approach makes it possible to achieve a significant extension of the attainable landing areas (over 70%) and, in some cases, to provide access to any point on the surface of Venus by increasing the flight time by one Venusian year.