Fifty years ago, almost to the date, the first major discovery of the Space Age, the discovery of the earth’s Radiation Belts, also known as Van Allen belts, occurred.  Following USSR’s successful launch of Sputnik on October,4 1957 that did not carry scientific instruments Professor Van Allen and his team launched the “ Explorer 3” satellite that carried a Geiger counter.  To their surprise when the spacecraft reached a few thousand kilometers in altitude there was an explosion of counts that caused one of the investigators to scream “ space is radioactive”.  They had discovered the Radiation Belts – donut-shaped regions encircling the earth where extremely energetic protons and electrons are trapped by the earth’s magnetic field. These are the regions where most spacecraft orbiting the earth, partly or entirely, operate and their performance as well as lifetime depends critically on the presence and dynamic behavior of the energetic particles.  In addition to practical considerations involving danger to satellites, astronauts and even some ground-based technologies, the Radiation Belts are the locus of fascinating non-linear collisionless plasma physics. Their structure, lifetime and energetics is controlled by strongly non-linear interactions of the energetic particles with large amplitude plasma waves generated locally by instabilities or injected from the earth by low frequency transmitters or lightning discharges. Following an introduction to the fundamental physics controlling the Radiation Belts the colloquium will focus on recent advances that aim not only on understanding and predicting the dynamics of the trapped particles but also in actively controlling their flux. Within this context fundamental physics issues concerning particle acceleration and scattering, collisionless diffusion, wave amplification and injection, and operation of low frequency antennas in the space plasma will be discussed.
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For more information, contact:

Adil Hassam
hassam@umd.edu
301-405- 1417

Arthur LaPorta
alaporta@umd.edu
301-405-3291