Tuesday, June 23, 2020

The Aurora Borealis seen from the International Space Station:  NASA astronaut Scott Kelly and ESA astronaut Tim Peake shot this beautiful image of the aurora over the Pacific Northwest from the International Space Station on January 20, 2016. Credit: ESA/NASA.


The atmosphere of the Sun, known as the solar corona, is comprised of a thin, hot plasma at more than a million degrees Celsius.  This super-heated plasma cannot be contained by the gravity of the Sun, but continually expands outward and escapes, ultimately immersing the entire solar system in the supersonic solar wind.  When the solar wind encounters the Earth, it forms a bow shock around the planet that abruptly halts its supersonic flow and converts its flow energy into heat in the plasma surrounding the Earth.  In addition, the resulting shock can also accelerate a small number ions and electrons to very high energies, contributing to the hazardous radiation environment around the Earth.  In fact, it is believed that the acceleration of ions at the shocks in the remnants of supernova explosions are responsible for the very highest energy particles that pervade interstellar and intergalactic space, known as cosmic rays.  This project, a collaborative effort between scientists at the University of Iowa, Princeton University, the University of Chicago, and NASA Goddard Space Flight Center, aims to use an innovative technique developed at the University of Iowa to investigate how shocks energize particles and accelerate them to high energies at the Earth's bowshock. The team will employ cutting-edge supercomputer simulations and sophisticated machine learning algorithms to predict and identify the characteristic signatures of the particle energization at the Earth's bowshock, ultimately seeking these signatures in spacecraft observations from NASA's Magnetospheric Multiscale mission.  An improved understanding of particle acceleration at shocks will help us to predict the extreme conditions of space weather that can damage GPS and communications satellites and can also harm astronauts, as well as to gain a more fundamental understanding of what processes generate the most energetic particles in the universe.