Close approach to Sun using gravity assists of the inner planets

Abstract

Earth, Mars, and Venus gravity assists used for the close approach to the Sun (down to 15 – 30 solar radii) are considered. A few spacecraft trajectories for launch in 2002 are suggested. Launch delta-V in LEO is 3.6 – 4.1 km/s and flight duration to the closest approach is 4.5 – 13.3 years for the trajectories. The advantages of this way of performing the solar mission are its low cost relatively to the Jupiter gravity assist and the possibility of multiple approach to the Sun. Multiple Mercury flyby is also possible. Some merits of the electric propulsion use for the mission are considered: it can perform the correction maneuvers, shorten the flight duration, lower the perihelion, turn the orbit plane.