[meteorite-list] Life Forms Ejected on Asteroid Impact Could Survive to Reseed Earth According to Study

[Ron Baalke]

http://www.liebertpub.com/prdetails.aspx?pr_id=618

Mary Ann Liebert, Inc.
For Immediate Release

Contact Vicki Cohn, (914) 740-2156, vcohn at liebertpub.com


Life Forms Ejected on Asteroid Impact Could Survive to Reseed Earth
According to a Study Published in Astrobiology

New Rochelle, February 26, 2008 - In the event that an asteroid or comet
would impact Earth and send rock fragments containing embedded
microorganisms into space, at least some of those organisms might
survive and reseed on Earth or another planetary surface able to support
life, according to a study published in the Spring 2008 (Volume 8,
Number 1) issue of Astrobiology
<http://www.liebertonline.com/toc/ast/8/1>, a peer-reviewed journal
published by Mary Ann Liebert, Inc <http://www.liebertpub.com/>. The
paper is available free online
<http://www.liebertonline.com/doi/pdfplus/10.1089/ast.2007.0134>.

In the report entitled, "Microbial Rock Inhabitants Survive
Hypervelocity Impacts on Mars-like Host Planets: First Phase of
Lithopanspermia Experimentally Tested",
<http://www.liebertonline.com/doi/pdfplus/10.1089/ast.2007.0134> Gerda
Horneck and colleagues describe systematic shock recovery experiments
designed to simulate a scenario called lithopanspermia, in which
microorganisms are transported between planets via meteorites. The first
step of lithopanspermia would involve ejection of the
microorganism-containing rock from the host planet as a result of an
impact event. The researchers sandwiched dry layers of three kinds of
biological test systems, including bacterial endospores, endolithic
cyanobacteria, and epilithic lichens, between gabbro discs, which are
analogous to martian rocks. They then simulated the shock pressures
martian meteorites experienced when they were ejected from Mars and
determined the ability of the organisms to survive the harsh conditions. 
 
The organisms selected represent "potential 'hitchhikers'
within impact-ejected rocks," explain the authors, and are hardy
examples of microbes that can withstand extreme environmental stress
conditions, write the authors.

The results support the potential for rocks ejected on
asteroidal impact to carry microorganisms capable of reseeding the
Earth, according to Horneck and coworkers, from the Institute of
Aerospace Medicine (Kon, Germany), Humboldt University of Berlin,
Heinrich-Heine University (Dusseldorf, Germany), Ernst-Mach Institute
for Short-Term Dynamics (Freiberg, Germany), Open University (Milton
Keynes, U.K.), the German Collection of Microorganism and Cell Cultures
(Braunschweig, Germany), the Russian Academy of Science (Moscow), and
the Planetary Science Institute (Tucson, AZ).

"Given that impacts have occurred on planetary bodies
throughout the history of our solar system," says journal Editor, Sherry
L. Cady, PhD, Associate Professor in the Department of Geology at
Portland State University, "the hypothesis that life in rock could have
been transferred between planets at different times during the past 3.5
billion years is plausible. These experiments advance our understanding
of the constraints on life's ability to survive the magnitude of impact
that would accompany a meteoric trip from Mars to Earth."

Astrobiology is an authoritative
peer-reviewed journal published bimonthly 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 <http://www.liebertonline.com/toc/ast/8/1>.

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 and to visitors of
The Astrobiology Web <http://www.astrobiology.com/>.