SwRI examines substorm in Earth's magnetotail with MMS data

SwRI examines substorm in Earth's magnetotail with MMS data
by Clarence Oxford
Los Angeles CA (SPX) May 15, 2024

Southwest Research Institute (SwRI) is analyzing an unusual event in Earth's magnetotail, the part of the magnetosphere trailing away from the Sun. Using data from NASA's Magnetospheric Multiscale (MMS) mission, SwRI scientists are studying substorms, disturbances in the magnetotail that release energy and can cause aurorae.

Since their launch in 2015, the MMS spacecraft have been examining the magnetopause, the boundary between the magnetosphere and surrounding plasma, for signs of magnetic reconnection, which occurs when magnetic field lines converge, break apart, and reconnect, converting magnetic energy into heat and kinetic energy. In 2017, MMS observed signs of magnetic reconnection in the magnetotail without the usual signs of a substorm, such as strong electrical currents and changes in the magnetic field.

"We want to see how the local physics observed by MMS affects the entire global magnetosphere," said SwRI's Dr. Andy Marshall, a postdoctoral researcher. "By comparing that event to more typical substorms, we are striving to improve our understanding of what causes a substorm and the relationship between substorms and reconnection."

During the one-year project, SwRI will compare MMS measurements of reconnection affecting local fields and particles to global magnetosphere reconstructions created by the Community Coordinated Modeling Center at NASA's Goddard Space Flight Center using the University of Michigan's Space Weather Modeling Framework.

"It's possible that significant differences exist between the global magnetotail convection patterns for substorms and non-substorm tail reconnection," Marshall said. "We have not looked at the movement of the magnetic field lines on a global scale, so it could be that this unusual substorm was a very localized occurrence that MMS happened to observe. If not, it could reshape our understanding of the relationship between tail-side reconnection and substorms."

MMS is the fourth NASA Solar Terrestrial Probes Program mission. Goddard Space Flight Center built, integrated, and tested the four MMS spacecraft and is responsible for overall mission management and operations. The principal investigator for the MMS instrument suite science team is based at SwRI in San Antonio. Science operations planning and instrument commanding are performed at the MMS Science Operations Center at the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder.