One of the tasks of ballistic design of flights to the planets of the solar system is to increase the spacecraft payload mass by reducing the mass of propellant spent on the mission. This important task requires finding economical ballistic flight scenarios. In this paper, the problem of interplanetary flight is considered in two different formulations, and the results obtained are compared. The problem of finding optimal dates for a two-impulse flight to the planets of the solar system is considered. Based on the obtained dates, the problem of designing a trajectory with an intermediate impulse was solved to reduce the characteristic velocity of an interplanetary flight. Using the example of flights to Mars and Venus, it is shown that the use of a deep space maneuver can significantly reduce the characteristic velocity compared to that of a standard two-impulse scheme with the same flight time.