[meteorite-list] Cosmic Dust in Ice Cores Sheds Light on Earth's Past Climate

From: E.P. Grondine <epgrondine_at_meteoritecentral.com>
Date: Sat Aug 5 09:43:25 2006
Message-ID: <20060805134321.65369.qmail_at_web36910.mail.mud.yahoo.com>

Hi Ron, all,

Once again, what these team measured was 3He and
cosmic dust - not comet dust.

It's best to announce research results like this in
August when Dr. Peiser is on vacation. That prevents
detailed technical comment by the world's best
qualified individuals.

The Brown Ammendment still stands as US law. While
some at NASA may want to try to evade their
responsibilities by rationalizations, in the end its
NASA's responsibility to see that the comet dust
studies are done, and trying to pass off cosmic dust
studies as comet dust studies will only lead to
embarassment.

good hunting,
EP

--- Ron Baalke <baalke_at_zagami.jpl.nasa.gov> wrote:

>
>
http://www.earthinstitute.columbia.edu/news/2006/story07-28-06b.php
>
> Earth Institute News
> July 28, 2006
>
> Contact: Ken Kostel
> 212-854-9729 or kkostel_at_ei.columbia.edu
>
> Contact: Clare Oh
> 212-854-5479 or coh_at_ei.columbia.edu
>
> Cosmic Dust in Ice Cores Sheds Light on Earth's Past
> Climate
>
> Each year nearly 40,000 tons of cosmic dust fall to
> Earth from outer
> space. Now, the first successful chronological study
> of extraterrestrial
> dust in Antarctic ice has shown that this amount has
> remained largely
> constant over the past 30,000 years, a finding that
> could help refine
> efforts to understand the timing and effects of
> changes in the Earth's
> past climate.
>
> The same study also used an improved analytical
> technique to show that
> dust carried to Antarctica from continental sources
> changed depending on
> climate.
>
> The study, which appears in the July 28 issue of the
> journal Science,
> involved researchers from the Lamont-Doherty Earth
> Observatory, a part
> of The Earth Institute, and the Alfred Wegener
> Institute for Polar and
> Marine Research (AWI) in Bremerhaven, Germany. The
> depth of the core
> they examined corresponded to the period between
> 6,800 and 29,000 years
> before the present day - a span that includes the
> height of the last
> glacial period, and the transition to warm
> conditions similar to today.
>
> The scientists collected particulate matter from the
> EPICA (European
> Project for Ice Coring in Antarctica) ice core and
> measured the
> concentration of helium-3 (3He), a rare isotope that
> is plentiful in the
> sun's solar wind and is carried to Earth imbedded in
> cosmic dust
> particles measuring just a few thousandths of a
> millimeter in diameter.
> These dust particles carry their exotic helium load
> to the Earth's
> surface where they are preserved in the snow and ice
> of the polar ice
> caps, among other places.
>
> Because ice cores from the polar caps provide a
> high-resolution temporal
> record of the past, the researchers were able to
> measure fine variations
> in the rate of cosmic dust accumulation between
> glacial and interglacial
> periods as well as the helium isotope
> characteristics of these rare
> particles. They found that the accumulation of
> cosmic dust did not
> change appreciably as the Earth emerged from the
> last great Ice Age and
> entered the current warm period, a fact that is
> likely to bolster the
> use of cosmic dust measuring techniques in future
> climate studies.
>
> In addition, this was the first study to examine
> both cosmic and
> terrestrial dust using the same helium-isotope
> technique. As a result,
> they also found that the composition of mineral dust
> particles carried
> by wind from the southern continents to Antarctica
> changed considerably
> as the Earth's climate changed.
>
> "The terrestrial dust coming down on Antarctica
> during the Ice Age
> obviously is not the same as that during warm
> periods," said Gisela
> Winckler, a Doherty associate research scientist at
> Lamont-Doherty and
> lead author on the study. "This may be due to the
> mineral dust
> originating from different regional sources or to
> changes in the process
> responsible for producing the dust."
>
> The project was supported by the Comer Science and
> Education Foundation.
>
> About the Lamont-Doherty Earth Observatory
>
> The Lamont-Doherty Earth Observatory, a member of
> The Earth Institute at
> Columbia University, is one of the world's leading
> research centers
> seeking fundamental knowledge about the origin,
> evolution and future of
> the natural world. More than 300 research scientists
> study the planet
> from its deepest interior to the outer reaches of
> its atmosphere, on
> every continent and in every ocean. From global
> climate change to
> earthquakes, volcanoes, nonrenewable resources,
> environmental hazards
> and beyond, Observatory scientists provide a
> rational basis for the
> difficult choices facing humankind in the planet's
> stewardship. For more
> information, visit www.ldeo.columbia.edu .
>
> About The Earth Institute
>
> The Earth Institute at Columbia University is the
> world's leading
> academic center for the integrated study of Earth,
> its environment and
> society. The Earth Institute builds upon excellence
> in the core
> disciplines - earth sciences, biological sciences,
> engineering sciences,
> social sciences and health sciences - and stresses
> cross-disciplinary
> approaches to complex problems. Through research,
> training and global
> partnerships, it mobilizes science and technology to
> advance sustainable
> development, while placing special emphasis on the
> needs of the world's
> poor. For more information, visit
> www.earth.columbia.edu .
>
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Received on Sat 05 Aug 2006 09:43:21 AM PDT