Mission design for Venusian projects of the 2021-2028 years epoch. Launch windows

Secure methods of the cost-effective flights to Venus and the passage of its gravity sphere are necessary to increase the amount of scientific and service equipment on board spacecraft and effectively exploration of the solar system. The results of the modern methods of ballistics design using for interplanetary flights to Venus in 2021–2028 epoch are given with the purpose of accomplishing a gravitational maneuver around it, or entering the Venusian satellite orbit for the landing on its surface. In the first work of the cycle the main attention is paid to the construction of the launch windows, the second work devoted to the calculation of the reachability areas of the descent vehicle on the surface of Venus.