NSF PR 96-20 - May 8, 1996
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Cheryl Dybas |
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Program contact: |
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Scientists to Present Results of 'Solar Storm' Research;
Massive Events Disrupt Power, Cause Aurora Displays
A giant "bubble" that erupted from the sun -- enhancing
aurora displays and causing voltage fluctuations on
trans oceanic communications cables as it rocketed
through space has been under study by National Science
Foundation (NSF) funded scientists. They will present
results of their research at the American Geophysical
Union meeting in Baltimore, Maryland, on Tuesday,
May 21st, at 8:30 a.m., in session SM21B, Studies
of Recent Geomagnetic Storms.
"It's important to study and understand these events
now, so we will have the ability to predict future
such 'solar storms' whose effects may be far greater,"
says Sunanda Basu, director of NSF's aeronomy program.
To test existing capabilities in space weather forecasts,
scientists identified a 'solar storm' in November,
1993. This magnetic storm produced effects only on
satellites and other sensitive systems. However, bigger
storms are likely during the next rise of the solar
cycle, which will peak at the turn of the century.
The project coordinator for the study, National Science
Foundation (NSF)-funded physicist Lt. Col. Delores
Knipp of the U.S. Air Force Academy, says that on
November 3rd and 4th, 1993, U.S. and Japanese spacecraft
detected a supersonic eruption from an active region
in the sun's atmosphere. The eruption became an interplanetary
hitchhiker by catching a ride on a particularly fast
stream of material leaving the sun's atmosphere.
Scientists believe this giant "bubble" rocketed through
space at speeds approaching 1.5 million miles per
hour and encountered the earth's magnetic shield only
60 hours after leaving the solar atmosphere. "In effect,
we had an interplanetary 'collision' right in our
own front yard," says Knipp.
She notes that earth's dipole field (the field that
makes compass needles point toward the polar region)
acts as a shield against such solar eruptions. "This
protective field is, magnetically speaking, pliable,
so it can deform to absorb the shock of such collisions.
However, in the process of absorbing the shock, energy
from it has to be redistributed," Knipp explains.
Data from the study indicate that the deformation
associated with this encounter was so severe that
satellites normally orbiting within the shield's protective
cover were exposed to a hot cloud of material. Energy
from the interaction ultimately fueled a magnetic
storm that generated large currents in earth's upper
atmosphere and induced response currents on the ground.
This is one of the first situations in which scientists
have been able to use multiple satellites to follow
such an event from the sun through interplanetary
space, and into earth's near-space and atmospheric
environment.
The research was inspired by the National Space Weather
Program (NSWP), a multi-agency effort to improve the
nation's ability to forecast solar events and their
resulting effects on earth. The NSWP was motivated
by the increasing susceptibility of man-made systems
to disturbances in the space environment.
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