Forecasting Radiation Hazards with Space Imaging

Jerry Goldstein, Daniel N. Baker, Bill R. Sandel, James L. Burch, Joseph F.
Fennell, Mark Weyland


The IMAGE satellite extreme ultraviolet (EUV) imager routinely obtains global
images of the He+ ions in the Earth's plasmasphere.  Using this space imaging
capability, the plasmasphere was observed to be drastically reduced in size
during the 2003 Halloween storm.  Before the storm the plasmasphere outer
boundary, the plasmapause, was seen at roughly 4 Earth radii (RE) geocentric
distance; after the storm, the plasmapause had moved inward of 2 RE.  This
dramatic erosion of the plasmasphere apparently had a profound effect on the
global distribution of the Van Allen radiation belts.  The plasmasphere is host
to electromagnetic waves known as "hiss", "chorus", and "whistlers" which act
(through wave-particle interactions) to remove the high-energy relativistic
electrons of the radiation belts.  The presence of the plasmasphere (with its
waves) acts to maintain the slot region, a shell between 2 and 3 RE with little
or no radiation belt electrons.  However, in the days following 2003 Halloween
storm's drastic plasmasphere erosion, an extremely intense new radiation belt
formed in what was formerly the slot region.  The new radiation belt posed a
radically increased hazard to astronauts in a region normally devoid of
radiation.  This apparent causality (remove the plasmasphere, form a new
radiation belt) implies a potential space weather application.  It may be
possible, with some reliability, to predict the formation of these new radiation
belts days in advance, using routine imaging (i.e., space weather monitoring) of
the plasmasphere.  Because of the potential benefit to the safety of a sustained
human presence in space, this possibility deserves further investigation.

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Invited Talk, Space Weather Week, Broomfield, CO, April 2005