[meteorite-list] Was There Life on Mars? Shiny Rock Coating May Hold the Answer

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri Jun 30 14:26:14 2006
Message-ID: <200606301823.LAA09942_at_zagami.jpl.nasa.gov>

http://www.imperial.ac.uk/P7911.htm

Was there life on Mars? Shiny rock coating may hold the answer

Imperial College London News Release
For immediate release
Friday 30 June 2006

A mysterious shiny coating found on rocks in many of Earth's arid
environments could reveal whether there was once life on Mars, according
to new research.

The research, published in the July edition of the journal Geology,
reveals that the dark coating known as desert varnish creates a record
of life around it, by binding traces of DNA, amino acids and other
organic compounds to desert rocks. Samples of Martian desert varnish
could therefore show whether there has been life on Mars at any stage
over the last 4.5 billion years.

The source of desert varnish has intrigued scientists since the mid
nineteenth century

The researchers hope that these results will encourage any future Mars
Sample Return mission to add desert varnish to its Martian shopping list.

The source of the varnish, which looks like it has been painted onto the
rocks, has intrigued scientists since the mid nineteenth century,
including Darwin, who was so fascinated that he asked the geochemist
Berzelius to investigate it. It was previously suggested that its dark
colour was the result of the presence of the mineral manganese oxide,
and that any traces of life found within the varnish came from
biological processes caused by microbes in this mineral.

However, the new research used a battery of techniques, including high
resolution electron microscopy, to show that any traces of life in the
varnish do not come from microbes in manganese oxide. The research
reveals that the most important mineral in the varnish is silica, which
means that biological processes are not significant in the varnish's
formation. On desert rock surfaces, silica is dissolved from other
minerals and then gels together to form a glaze, trapping organic traces
from its surroundings.

Desert varnish was used to create images known as petroglyphs like these
in Grimes Point, Nevada

Dr Randall Perry, lead author of the research from the Department of
Earth Science and Engineering at Imperial College London, explained that
as life is not involved in desert varnish formation, the varnish can act
as an indicator of whether life was present or absent in the local
environment.

Dr Perry said: "If silica exists in varnish-like coatings in Martian
deserts or caves, then it may entomb ancient microbes or chemical
signatures of previous life there, too. Desert varnish forms over tens
of thousands of years and the deepest, oldest layers in the varnish may
have formed in very different conditions to the shallowest, youngest layer.

"These lustrous chroniclers of the local surroundings can provide a
window back in time. Martian desert varnish would contain a fascinating
chronology of the Martian setting," he added.

The research was carried out by researchers at Imperial College and the
Universities of Auckland (NZ); Wisconsin-Parkside and Washington (US);
and Nottingham Trent (UK).

*** Images of rocks covered with black desert varnish in Death Valley
California and Petroglyphs from Grimes Point Nevada (dating back
thousands of years) are available ***

-ends-

For further information please contact:

Laura Gallagher
Imperial College London Press Office
Email: l.gallagher_at_imperial.ac.uk
Tel: 020 7594 6702

Notes to editors:

Baking black opal in the desert sun: The importance of silica in desert
varnish Geology Volume 34, Number 7, July 2006
Randall S. Perry (1),(6), Bridget Y. Lynne (2), Mark A. Sephton (1),
Vera M. Kolb (3), Carole C. Perry (4), James T. Staley (5)

(1) Department of Earth Science and Engineering, Imperial College London, UK
(2) Department of Geology, University of Auckland, New Zealand
(3) Department of Chemistry, University of Wisconsin-Parkside, USA
(4) Chemistry Division, Nottingham Trent University, UK
(5) Department of Microbiology, University of Washington, USA
(6) Planetary Science Institute, Washington, USA
An online preview edition of the paper can be viewed here:
wwwgsajournals.org/gsaonline/?request=get-document&doi=10.1130%2FG22352A.1
<http://www.gsajournals.org/gsaonline/?request=get-document&doi=10.1130%2FG22352A.1>

About desert varnish

* Desert varnish is found across the world in areas including the
Atacama desert in Chile, the Mojave desert in Southern California, USA
and Canyonlands National Park, Utah, USA.

* It is often found on canyon walls.

* It is one of fourteen different types of rock coatings.

* Desert varnish was used by prehistoric and Neolithic people to create
images known as petroglyphs, which they crafted by scraping away the
dark varnish to reveal the light rock underneath.

* Desert varnish is sometimes mistaken for fusion crust, the melted
glassy exterior of a meteorite that forms when the meteorite passes
through the atmosphere.

About Imperial College London

Consistently rated in the top three UK university institutions, Imperial
College London is a world leading science-based university whose
reputation for excellence in teaching and research attracts students
(11,000) and staff (6,000) of the highest international quality.
Innovative research at the College explores the interface between
science, medicine, engineering and management and delivers practical
solutions that enhance the quality of life and the environment -
underpinned by a dynamic enterprise culture.
Website: www.imperial.ac.uk
Received on Fri 30 Jun 2006 02:23:51 PM PDT