Trajectory Design of Solar Probe+ Using Multiple Venus Gravity Assists

Abstract

A new trajectory for the Solar Probe+ mission is developed, which uses seven unpowered Venus gravity assist flybys to reach the Sun with repeated near-Sun passes in 6 years, at a closest approach distance of 8.5 solar radii (RS) from the Sun’s surface. The trajectory consists of 24 solar passes whose perihelion gradually decreases from 35 RS down to 9.5 RS, enabling thorough, timely, direct in situ measurements of the inner heliosphere region during 3 to 4 solar passes per year over more than half of the solar cycle. As the top mission enabler, the trajectory design introduced a new mission concept for the long-studied Solar Probe mission and made it possible for Solar Probe to move on to NASA’s mission plan for anticipated launch in 2015.