Investigating the Complex Heliosheath of our Heliospheric Shield

The solar wind travels supersonically in the solar system until it reaches the termination shock, where itis slowed down due to the interplay between the interstellar medium (ISM) and heliosphere. The regionof slowed down solar wind is referred to as the heliosheath, where a great number of mysteries remainunsolved. Within the SHIELD NASA Drive Center, investigating the physical processes within theheliosheath and their consequences is a fundamental goal in understanding both the shape of theheliosphere and also how it protects the solar system from harmful galactic cosmic rays. Here, wehighlight some of the findings of SHIELD: (1) a Rayleigh-Taylor like instability develops in theheliosheath due to charge exchange, which in turn allows for mixing between the solar wind and ISMplasma yielding a short, “croissant-like” heliotail; (2) via magnetohydrodynamic modeling, we cancapture this mixing region, which has potential implications for particle acceleration; (3) currentenergetic neutral atom (ENA) observations appear to be insufficient for distinguishing the true shape ofthe heliotail, but future ENA-focused missions, such as IMAP, will have the capability to determine theshape of the heliotail; (4) ENA observations of the heliotail and Lyman-alpha observations may also beable to reveal the properties of the interstellar magnetic field