Solar Orbiter, the first probe in the joint ESA-NASA HELiophysical EXplorers (HELEX) program, aims to better our understanding of the solar atmosphere and the dynamic solar wind. Solar Orbiter is scheduled to launch in 2017 with a primary mission duration of 7 years. The orbit of Solar Orbiter - between 0.9 AU at aphelion and 0.28 AU at perihelion - will allow for a comprehensive study of solar wind evolution. Additionally, over the course of the mission, Solar Orbiter will increase its inclination to the solar equator over time, through the use of gravity assists from Venus, and reach an inclination of 34°.
The Heavy Ion Sensor (HIS), part of the Solar Wind plasma Analyzer (SWA) instrument suite on Solar Orbiter, is currently in development at SwRI. HIS will measure the composition and kinetic properties of heavy ions (He, C, O, Ne, Mg, Si, and Fe - for a variety of charge states) in the solar wind, as well as the composition and velocity distribution functions of major heavy ion constituents in the suprathermal energy range (up to ~100 keV/q). These measurements will allow for a comprehensive study of minor ion species in the solar wind allowing for characterization of the origin of the solar wind and parameterization of the corona, along with solar wind evolution.