HElium Resonance Scattering in the Corona and HELiosphere (HERSCHEL)

The proposed HERSCHEL (HElium Resonance Scattering in the Corona and HELiosphere) program will investigate coronal heating and solar wind acceleration from a range of solar source structures by obtaining simultaneous observations of the electron, proton and helium solar coronae. The HERSCHEL will establish proof-of-principle for the Ultra-Violet Coronagraph (UVC), which is in the ESA Solar Orbiter Mission baseline. The NRL Solar Physics Branch is joining with the Italian UVC Consortium to address the objectives of the International Living With a Star program with this combination of NASA suborbital program and ESA Solar Orbiter flight opportunities. Indeed, while the Solar Orbiter flight is still many years away, the 3 year program being proposed here is essential in order to prove the validity of this exciting new concept before the Solar Orbiter instrument selection is finalized. This proposal aims to develop instrumentation that for the first time will directly image and characterize on a global coronal scale the two must abundant elements, hydrogen and helium. This will directly address three outstanding questions in the Sun-Earth Connection theme: 1) Origin of the slow solar wind, 2) Acceleration mechanisms of the fast solar wind, and 3) Variation of Helium abundance in coronal structures. Additionally, by establishing proof of concept for the UVC on Solar Orbiter, this will facilitate future investigations of CME's kinematics, and solar cycle evolution of the electron, proton, and helium coronae. Lastly, this mission fits the goals of the International Living With a Star (ILWS) program. This work has been supported by the Office of Naval Research.