Expanding Possible Landing Areas on the Surface of Venus by using Gravity Assist Maneuvers
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