[Bionews] Astrobiology

Masi, Paula PMasi at liebertpub.com
Wed Jul 5 08:44:08 EST 2006


For immediate release

 

Contact: Vicki Cohn, Mary Ann Liebert, Inc., (914) 740-2100, ext. 2156,
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Oxygen Trapped in Europa's Icy Surface May Offer Clues 


to Moon's Habitability

 
New Rochelle, NY, July 5, 2006 - The production of chemically reactive
oxidants on the surface of Mars and icy moons such as Europa may provide
clues to their habitability and offers new avenues for future space
exploration and the analysis of surface soil and ice shells, according
to three Special Papers published in the most recent (Volume 6, Number
3) issue of Astrobiology, a peer-reviewed journal published by Mary Ann
Liebert, Inc. 
Astrobiology is the leading peer-reviewed journal in its field.  To
promote this developing field, the Journal has teamed up with The
Astrobiology Web to highlight one outstanding paper per issue of
Astrobiology.  This paper is available free online at
www.liebertpub.com/ast and to visitors of The Astrobiology Web at
www.astrobiology.com <http://www.astrobiology.com/>  
            In a Special Paper entitled, "Clathrate Hydrates of Oxidants
in the Ice Shell of Europa," Kevin Hand, Christopher Chyba, Robert
Carlson, and John Cooper present the following hypothesis: that the
formation of mixed clathrate compounds could make up 12% to 53% of the
moon's ice shell and stably trap O2 and other gaseous oxidants within
the ice. The clathrate compounds, which consist of a lattice, or cage,
made of H2O molecules, could trap a variety of gas molecules including
O2, CO2, and SO2 produced by radiation-induced chemistry at Europa's
surface. Mixed gas clathrates are more stable, yet denser, at Europa's
outer surface than pure O2 clathrates and could more easily sink through
the thick ice crust to the subsurface ocean.
            In regions of pure H2O ice, oxygen produced by radiation
escapes from the relatively unstable pure O2 clathrate to form Europa's
extremely thin oxygen atmosphere. Earlier Hubble Space Telescope
measurements indicate that the atmosphere appears denser over the pure
water-ice regions than over sulfate-rich regions where the mixed gas
clathrates form. This finding may be further confirmed next March during
the New Horizons spacecraft flyby through the Jovian system en route to
Pluto.
            The authors, from Stanford University, the SETI Institute,
Princeton University, NASA Jet Propulsion Laboratory and NASA Goddard
Space Flight Center, also describe the usefulness of Raman spectroscopy
for studying clathrates and detecting life forms. They propose a role
for this instrument on future spacecraft landers for studying the
characteristics of the moon's icy surface and the habitability of
Europa.
"The Hand et al. hypothesis is intriguing for a couple of reasons," says
journal Editor-in-Chief, Sherry L. Cady, Ph.D., Associate Professor in
the Department of Geology at Portland State University. "The presence of
O2 enclathrating compounds not only explains the paradoxical occurrence
of solid O2 on the europan surface, but it provides a plausible
mechanism for delivering O2 to the europan ocean, which may be oxidant
limited. This work has important implications for habitability
assessments of Europa."  
            In a second Special Paper in this issue of the journal,
Gregory Delory, William Farrell, Sushil Atreya, et al. conclude that
electrically charged dust could greatly increase the production of the
oxidant hydrogen peroxide on Mars, and this could explain the inability
of the Viking spacecraft to detect organic materials and signs of
possible life. 
            The authors propose that dust devils and dust storms on Mars
generate electrostatic fields-similar to the electric fields produced by
thunderstorms on Earth--capable of transforming carbon dioxide and water
into the precursors of H2O2. In their paper entitled, "Oxidant
Enhancement in Martian Dust Devils and Storms," the authors, from the
University of California, Berkeley, NASA Goddard Space Flight Center,
the University of Michigan, Ann Arbor, Duke University, the University
of Alaska, Fairbanks, the SETI Institute, Southwest Research Institute,
the University of Washington, Seattle, and the University of Bristol
(U.K.), used a plasma physics model to determine that the strong
electric fields produced by dust storms can drive atmospheric chemical
reactions that enhance oxidant production.
            In a companion paper, Sushil Atreya, Ah-San Wong, Nilton
Renno, et al. propose that hydrogen peroxide-formed by chemical
reactions induced by electrostatic fields generated by sand and dust in
martian dust devils and storms-or another superoxide formed from
hydrogen peroxide may be responsible for scavenging organic material
from Mars and could accelerate the loss of methane from the martian
atmosphere. 
            Astrobiology is an authoritative peer-reviewed journal
published both in print and online. The Journal provides a forum for
scientists seeking to advance our understanding of life's origins,
evolution, distribution and destiny in the universe. A complete table of
contents and a full text for this issue may be viewed online at
www.liebertpub.com/ast
            Mary Ann Liebert, Inc., is a privately held, fully
integrated media company known for establishing authoritative
peer-reviewed journals in many promising areas of science and biomedical
research. Its biotechnology trade magazine, Genetic Engineering News
(GEN), was the first in its field and is today the industry's most
widely read publication worldwide. A complete list of the firm's 60
journals, books, and newsmagazines is available at www.liebertpub.com
<http://www.liebertpub.com/> . 
 
Mary Ann Liebert, Inc.    140 Huguenot St., New Rochelle, NY 10801-5215
www.liebertpub.com <http://www.liebertpub.com/> 
                                  Phone: (914) 740-2100    (800)
M-LIEBERT    Fax:  (914) 740-2101
 
 
 


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