April 21, 2014 - SPA associate professor Jacobus le Roux has been awarded a three-year NASA grant in the amount of $396,000 as part of the 2013 Heliopshysics Supporting Research (HSR) program, to study the boundary of the solar system known as the heliopause, using theory and computer simulations. This project supports the NASA science goal for heliophysics to understand the Sun and its interaction with the solar system, the NASA science question of how the Heliosphere respond to solar variability, and the NASA science area objective to understand the fundamental physical processes of the space environment from the Sun and beyond to the interstellar medium. Recent observations by Voyager 1 of energetic charged particles with energies >40 keV suggest that the spacecraft crossed for the first time a boundary at ~122 AU from the Sun that appears to belong to the heliopause, the region separating the heliosheath from the local interstellar medium. However, the Voyager 1 observations do not in all respects reflect our expectation for a heliopause crossing. This suggests that the physics of the heliopause region is surprising and more complicated than expected. The Voyager mission provides a unique, perhaps never-to-be-repeated opportunity to probe the fundamental physics of the heliopause region. The main goal of this project is to use energetic charged particles and their mobility as a tool to infer the fundamental physics of the heliopause region, including the large-scale structure of the magnetic field and its turbulence characteristics.