LAS Meeting Oct 19 - Dr. Dan Baker, Director of LASP

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Date: 

Thursday, October 19, 2017 - 7:00pm

Presentation:

"Studying Relativistic Particles in Our Cosmic Backyard: Van Allen Belt Exploration" by Dan Baker, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA.

The first major scientific discovery of the Space Age was that the Earth is enshrouded in toroids, or “belts”, of very high-energy magnetically trapped charged particles. Early observations of the radiation environment suggested that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. Subsequent studies showed that electrons in the energy range up to a million electron Volts (MeV) often populated both the inner and outer zones with a pronounced “slot” region relatively devoid of energetic electrons existing between them. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. However, recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed wholly unexpected properties of the radiation belts, especially at highly relativistic (E > 2 MeV) and ultra-relativistic (E > 5 MeV) kinetic energies. In this presentation I show using high spatial and temporal resolution data from the University of Colorado’s Relativistic Electron-Proton Telescope (REPT) experiment on board the Van Allen Probes that multiple belts can exist concurrently and that an exceedingly sharp inner boundary exists for ultra-relativistic electrons. Using additionally available Van Allen Probes data, I demonstrate that these remarkable features of energetic electrons are not due to a physical boundary within Earth’s intrinsic magnetic field. Rather it likely that human-generated electromagnetic transmitter wave fields help produce such effects. We conclude from these unique measurements that human-made wave-particle scattering effects deep inside the Earth’s magnetosphere can contribute to an almost “impenetrable” barrier through which the most energetic Van Allen belt electrons often cannot migrate.

Location:

The meeting will be at the IHOP Restaurant, 2040 Ken Pratt Boulevard, Longmont. Please join us for coffee, dinner, or just desert around 6 pm; the meeting will begin at 7 pm.