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["Károly Tóth" <zeroglab@freemail.c3.hu>]

first published by mateor news agency the hague nl
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---------- Forwarded message ----------
Date: Thu, 10 Dec 1998 00:29:40 +0100 (CET)
From: kabubah <mnews@xs4all.nl>

mnews is ge-abonneerd op de pressreelases van
nasa: eindelijk echt nieuws (maar of we daar zo
lbij mee zijn...)


mnews has subscribed the pressreleases of nasa. real news finally (still
unclear if it makes us happy)
(translation:0glab)

Don Savage
Headquarters, Washington, DC
December 8, 1998
(Phone:  202/358-1547)

Bill Steigerwald
Goddard Space Flight Center, Greenbelt, MD
(Phone:  301/286-5017)

RELEASE:  98-221

SOLAR WIND SQUEEZES SOME OF EARTH'S ATMOSPHERE
INTO
SPACE

Researchers using NASA's Polar spacecraft
have found the first direct evidence that bursts
of energy from the Sun can cause oxygen and other
gases to gush from Earth's upper atmosphere into
space.  Scientists first saw this effect September
24-25, 1998, when a storm from the Sun smacked
into the Earth.  Using particle detectors on Polar,
they found that the flow of "polar wind" out of
Earth's upper atmosphere increased substantially
when the storm hit. In effect, pressure from the
solar ejection squeezed gas out of the
ionosphere.

Scientists have known since the early 1980s
that Earth's upper atmosphere leaks oxygen,
helium, and hydrogen ions (atoms that have gained
or lost an electron) into space from regions near
the poles.  But it was not until the Polar
spacecraft flew through this fountain of ionized
gas in September 1998 that scientists confirmed
that the flow of ions was caused by solar
activity.

"We now have the first direct, quantifiable
evidence that disturbances in the solar wind
produce changes in the flow of ions out of the
ionosphere," said Dr.Thomas E. Moore of NASA's
Goddard Space Flight Center, Greenbelt,
MD, principal investigator for Polar's Thermal Ion
Dynamics Experiment (TIDE).  "This solar wind
energy essentially 'cooks' the upper atmosphere
off of the Earth." Moore's observations were
presented on December 8 in San Francisco,
CA, during the fall meeting of the American
Geophysical Union.

On September 22, 1998, the Sun ejected a
mass of hot, ionized gas (known as plasma) toward
Earth.  This magnetic
cloud of plasma (called a coronal mass ejection)
increased the density and pressure of the solar
wind and produced a shock wave similar to a sonic
boom.  When that shock wave arrived at Earth late
on September 24, it rammed into and compressed
Earth's magnetic shell in space (the
magnetosphere).  This shock to the magnetosphere
excited the plasma trapped in Earth's ionosphere
to a point where some ions gained enough energy to
escape Earth's gravity and flow downwind of Earth.
The amount of oxygen and other gases lost from the
ionosphere amounted to a few hundred tons, roughly
equivalent to the mass of oxygen inside the
Louisiana Superdome.

"This is the supply of plasma that makes things
interesting in space," said Moore.  "Much of the
gas ejected from the ionosphere is caught in
Earth's wake.  It then flows back toward the Earth
while being heated and accelerated by the same
processes that create auroral particles and the
radiation belts."

The ionosphere is a series of invisible layers of
ions and electrons that are suspended in Earth's
upper atmosphere at about 50 to 650 miles (80 to
1,000 kilometers) in altitude. These particles are
produced when the Sun's ultraviolet light ionizes
the atoms and molecules in the upper atmosphere.
The ionosphere makes long-distance radio
communication possible by reflecting radio waves
back to Earth.  It also is home to the aurora and
the electrical currents that heat the upper
atmosphere during magnetic storms.

"Our research shows that Earth's own ionosphere is
a major contributor to the growth of space
storms," said Barbara Giles, a co-investigator on
the TIDE team and researcher at Goddard.  "These
new observations will help us understand the
conditions that enable space storms to form,
thereby moving one step closer to the forecasting
of the most damaging storms."

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