Remote Sensing of Earth's Magnetosphere with Energetic Charged Particles

Professor Robyn Millan; Department of Physics and Astronomy, Dartmouth College

Earth’s magnetic bubble, the magnetosphere, provides a close-up view of how a star interacts with its magnetized planets. Driven by the solar wind, the magnetosphere’s intense storms, explosive substorms, and spectacular aurora are governed by a global circulation, known as magnetospheric convection. Earth’s magnetic tail plays an important role in this convection cycle; how the magnetotail maintains steady convection, and when and how it decides to explosively release stored energy, are long-standing questions. Magnetospheric convection involves dynamics at different scales, ranging from the largest (system-size) to the smallest (kinetic). At the largest scales, the spatial structure of the magnetic field is thought to play an important role in the stability of the magnetotail. At the smallest scales, plasma waves interact with energetic particles, leading to both their acceleration and loss into Earth’s atmosphere. 

Low-altitude measurements provide a unique vantage point for studying processes occurring in the magnetosphere, taking advantage of the fact that energetic particles move quickly along magnetic field lines, carrying information about processes occurring near the equator. Low-earth orbiting polar satellites sample a vast volume of space as they rapidly traverse magnetic field lines, providing a platform for studying the multiscale nature of the dynamics. This presentation will discuss two experiments that use energetic particles to remotely sense the magnetosphere. REAL (Relativistic Electron Atmospheric Loss) is a CubeSat mission that will make high time resolution (~50 ms) measurements of energetic particles over a wide energy range (~1 keV to 2 MeV), revealing information about the physics of plasma wave-particle interactions. CINEMA (Cross-scale INvestigation of Earth’s Magnetotail and Aurora) is a mission concept that uses a constellation of nine satellites to remotely sense the structure and dynamics of the magnetosphere, providing the first system-level, cross-scale view of magnetotail convection. 

Bio: Robyn Millan is an experimental physicist specializing in the processes acting on energetic particles in both the atmosphere and in space, and in developing new experimental methods for studying these processes. She has also worked to promote the development of small satellites for space science, and is currently serving as co-chair of the Decadal Survey for Solar and Space Physics. She has undergraduate degrees in Physics and Astronomy from U. C. Berkeley (1995) and a PhD in Physics from U. C. Berkeley (2002). She came to Dartmouth in 2002 as a NASA Spacegrant Visiting Young Scientist and joined the regular faculty in 2005. 

Dr. Millan's research uses satellites and high-altitude scientific balloons to study the near-Earth space environment. She is particularly interested in using low-altitude measurements to remotely sense energetic particle processes that occur farther from the planet. She is Principal Investigator (PI) of the NASA Relativistic Electron Atmospheric Loss (REAL) CubeSat and was PI of the Balloon Array for Radiation-belt Relativistic Electron Losses (BARREL).

To partipate in the colloquium virtually via Zoom, go to https://uiowa.zoom.us/j/96790857586

There will be a reception at 3 p.m. in 316 VAN. After the colloquium, there will be a meet and greet for graduate students and post-doctoral researchers who would like to speak with Professor Millan - it will begin at approximately 4:30 in 309 VAN.