[meteorite-list] Martian Rock 'Does Contain Life' (ALH84001 Meteorite)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:07:03 2004
Message-ID: <200210231808.LAA09027_at_zagami.jpl.nasa.gov>

http://news.bbc.co.uk/1/hi/sci/tech/2354533.stm

Martian rock 'does contain life'
By Dr David Whitehouse
BBC News
October 23, 2002

The strange shapes seen in a rock from Mars that some researchers say are
fossilised bacteria really are tiny micro organisms, say American
researchers.

But while they are confident the Mars rock contains fossilised life they
cannot quite bring themselves to say it comes from the Red Planet, it might
be Earthly contamination.

Despite the uncertainty about their origin establishing that the small
structures really were living things, and not just mineral globules, would
be an advance in a field that has sharply divided opinions.

Lawrence Taylor of the University of Tennessee told BBC News Online that
so-called "nannobacteria" found on Earth resemble those found in the Mars
rock." The next task is to find a way to determine if they really came from
Mars.

Life on Mars?

Since the dramatic announcement in 1996 by Nasa scientists that there were
several lines of evidence that suggested rock ALH84001, picked up from
Antarctic ice but originally from Mars, contained evidence of life,
scientific opinion has been divided between those who wanted to be
persuaded, and those who did not.

Since then the rock has been extensively analysed and many papers written,
but few have shifted their viewpoints.

One camp has looked at magnetic grains in the microfossils saying that they
appear identical to magnetic grains found in some terrestrial bacteria.
Another group of researchers looked at indications of how carbon deposits in
the rock were formed looking to see if they were deposited at low enough
temperatures so they could be by-products of life.

Rival researchers have argued that the very small size of the purported
micro organisms make it unlikely that they were living things because they
are too small.

In the past few years however some researchers, principally Robert Folk of
the University of Texas, have put forward evidence that terrestrial
nannobacteria do exist and add significantly to the Earth's biomass.

The latest study, by Robert Folk and Lawrence Taylor, casts doubt on the
lower size limit for life viewpoint. Some of the larger bacteria found in
ALH2004 are actually close in size to the smallest terrestrial organisms.

But if the case for the fossilised micro organisms in ALH84001 is
strengthened somewhat the big question remains: where did they come from?

"We conclude that the nanobodies that are so abundant in ALH84001 are indeed
nannobacteria. However whether these bodies originated on Mars, or are
Antarctic contamination remains a valid question," say the researchers.
Received on Wed 23 Oct 2002 02:08:56 PM PDT