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NASA Study Suggests Giant Space Clouds Iced Earth

A team of researchers from the University of California, Santa Cruz
(UCSC), University of California, Berkeley (UC Berkeley), and the University
of British Columbia (UBC), Vancouver, Canada , reported new findings about
these bursts of energy, called terrestrial gamma ray flashes (TGFs) .

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WASHINGTON, Eons ago, giant clouds in space may
have led to global extinctions, according to two recent technical papers
supported by NASA's Astrobiology Institute.

NASA Satellite Observes Mysterious Earth Energy

It was designed to
study X-rays and gamma rays from solar flares. If we can understand the process here, it might give us insights
into similar processes in less accessible parts of the universe," said David
Smith, an assistant professor of physics at UCSC and first author of the
paper .

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RHESSI, a NASA Small Explorer spacecraft, was launched on Feb.

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It also supports research aimed
toward understanding the geochemical nature of the solar system's bodies, such
as planets, Earth 's moon, satellites of the outer planets, and small bodies. This resulted in global
extinctions, according to the second paper. He is a scientist at the University of Colorado, Boulder. The big mystery revolves around
how they are triggered," Pavlov said.

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Normally, Earth's magnetic field and ozone layer
protect life from cosmic rays and the sun's dangerous ultraviolet radiation.

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"This is a very interesting process involving extreme physics right here
on Earth. 2, 2002.
For more information, images and animations regarding this research on the
Internet, visit:

http://www.

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WASHINGTON, Scientists using observations from
NASA's Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite
detected flashes of gamma ray energy in Earth's upper atmosphere in greater
detail than ever before. This results in a
powerful electric field between the cloud tops and the ionosphere, the outer
layer of Earth's atmosphere.

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The program supports research to conduct laboratory studies of a variety
of extraterrestrial materials such as meteorites, cosmic dust, and lunar
samples, which are cosmochemical in nature. This also increases the flow
of cosmic rays towards Earth.nasa.

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RHESSI is part of NASA's Sun-Earth Connection program. "What's exciting is we are getting data
good enough for the theorists to really test their models.
Their report was published last week in the journal Science.gov

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In a more likely scenario, less dense giant molecular clouds may have
enabled charged particles to enter Earth's atmosphere, leading to destruction
of much of the planet's protective ozone layer.

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The maximum grants' value is $1,126 ,000. Because it remains beyond Earth's orbit, the
heliosphere continues to deflect dust particles away from the planet.nasa.

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Moderately dense space clouds are huge, and the solar system could take as
long as 500,000 years to cross one of them.
TGFs are very short blasts of gamma rays , lasting about one millisecond,
emitted into space from Earth's upper atmosphere.

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nasa.
However , because of the large flow of hydrogen from space clouds into the
sun's heliosphere, the sun greatly increases its production of electrically
charged cosmic rays from the hydrogen particles. During a
reversal, electrically charged cosmic rays can enter Earth's atmosphere
instead of being deflected by the planet's magnetic field. Observations from RHESSI
raised the maximum recorded energy of TGFs by a factor of 10, and indicate
Earth gives off approximately 50 TGFs or more daily.
While it remains unknown exactly how electron beams accelerate fast enough
to produce TGFs, Smith said it may involve the build-up of electric charge at
the tops of thunder clouds due to lightning discharges .

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Pavlov said this hypothesis has to be tested by geologists. He outlined a complex series of events
that would result in loss of much of Earth's protective ozone layer, if the
solar system collided with a moderately dense space cloud.

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WASHINGTON, NASA's Science Mission Directorate,
Solar System Division, Washington, selected the University of Chicago,
Chicago, for grants to support the agency's Cosmochemistry Research Program.
Sudden, small changes in the uranium 235/238-ratio in rock layers would be
proof interstellar material is present that originated from supernovae.
Cosmic rays can fly into the atmosphere and break up nitrogen molecules to
form nitrogen oxides . Nitrogen oxide catalysts would set off the destruction
of as much as 40 percent of the protective ozone in the planet's upper
atmosphere across the globe and destruction of about 80 percent of the ozone
over the polar regions according to Pavlov. They are thought to be
emitted by electrons traveling at 99. "The energies we see are as high as those of gamma rays emitted from
black holes and neutron stars," Smith said. The analysis of additional data is ongoing.

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For information about NASA and agency programs on the Web, visit:

http://www. Both recently appeared in the
Geophysical Research Letters. They would
look at Earth's rocks to find layers that relate to the snowball glaciations
to assess whether uranium 235 is present in higher amounts., and the
University of California, Berkeley, Calif.nasa.

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The
resulting dust layer hovering over the Earth would absorb and scatter solar
radiation, yet allow heat to escape from the planet into space, causing
runaway ice buildup and snowball glaciations. It presents the
first analysis for TGFs covering the results from a search of three months of
RHESSI data.gov/vision/universe/solarsystem /rhessi_tgf.

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"There are indications from 600 to 800 million years ago; at least two of
four glaciations were snowball glaciations."
TGFs have been correlated with lightning strikes and may be related to
visible phenomena that occur in the upper atmosphere over thunderstorms.

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The research also supports the Vision for Space Exploration, NASA's long-
term plan to return astronauts to the moon and extend exploration to Mars and
beyond. It cannot be
produced naturally on Earth or in the solar system, but it is constantly
produced in space clouds by exploding stars called supernovae . Once in such a cloud, the Earth
would be expected to undergo at least one magnetic reversal.
For information about NASA and agency programs on the Internet, visit:

http://www. However, RHESSI's detectors
pick up gamma rays from a variety of sources.

The Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray
Observatory first discovered TGFs in 1994.

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The program also covers cosmochemical studies concerned with the formation and
chemical development of the solar system.
One paper outlines a rare scenario in which Earth iced over during
snowball glaciations, after the solar system passed through dense space
clouds .
The research outlined a scenario that begins as Earth passes through a
moderately dense space cloud that cannot compress the outer edge of the sun's
heliosphere into a region within the Earth 's orbit.

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99 percent of the speed of light (186,000
mps), when they scatter off of atoms and decelerate in the upper atmosphere. However, BATSE's ability to count
the TGFs or measure their peak energies was limited.
"Regardless of the exact mechanism, there is some enormous particle
accelerator in the upper atmosphere that is accelerating electrons to these
very high energies, so they emit gamma rays when they hit the sparse atoms of
the upper atmosphere," Smith said.

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For information about NASA and agency programs on the Internet, visit:

http://www.

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The heliosphere is the
expanse that begins at the sun's surface and usually reaches far past the
orbits of the planets.
RHESSI investigators plan to collaborate with other researchers to investigate
how various phenomena are related, Smith said.

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He concluded the snowball glaciations
covered the entire Earth.
Collisions of the solar system with dense space clouds are rare, but according
to Pavlov's research, more frequent solar system collisions, with moderately
dense space clouds, can be devastating.
It is managed by NASA's Goddard Space Flight Center, Greenbelt, Md.

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"Computer models show dramatic climate change can be caused by
interstellar dust accumulating in Earth's atmosphere during the solar system's
immersion into a dense space cloud," said Alex Pavlov , principal author of the
two papers.
Smith worked with RHESSI principal investigator Robert Lin at UC Berkeley
and Christopher Barrington-Leigh, now at UBC, to plan ways they could use the
satellite for a range of investigations in addition to studying solar flares.