Freethought & Rationalism Archive

Coragyps · 08-02-2002, 05:11 PM

A press release from NASA:

Quote:

From: NASANews@h...
Date: Fri Aug 2, 2002 1:50 pm
Subject: RESEARCHERS PUBLISH LATEST RESULTS IN CONTINUING SEARCH FOR ANCIENT MARTIAN LIFE
To: undisclosed-recipients:;

Dwayne Brown
Headquarters, Washington August 2, 2002
(Phone: 202/358-1726)

Catherine E. Watson
Johnson Space Center, Houston
(Phone: 281/483-5111)

RELEASE: 02-150

RESEARCHERS PUBLISH LATEST RESULTS
IN CONTINUING SEARCH FOR ANCIENT MARTIAN LIFE

In the latest study of a 4.5 billion-year-old Martian
meteorite, researchers have presented new evidence confirming
that 25 percent of the magnetic material in the meteorite was
produced by ancient bacteria on Mars. These latest results
were published in the journal Applied and Environmental
Microbiology.

The researchers used six physical properties they refer to as
the Magnetite Assay for Biogenicity (MAB) to compare all the
magnetic material found in the ancient meteorite -- using the
MAB as a biosignature. A biosignature is a physical and/or
chemical marker of life that does not occur through random
processes or human intervention.

"No non-biologic magnetite population, whether produced by
nature or in the laboratory, has ever met the MAB criteria,"
said Kathie Thomas-Keprta, an astrobiologist at NASA's
Johnson Space Center (JSC) in Houston and the lead researcher
on the study. "This means that one-quarter of the magnetite
crystals embedded in the carbonates in Martian meteorite
ALH84001 require the intervention of biology to explain their
presence."

Magnetotactic bacteria, which occur in aquatic habitats on
Earth, arrange magnetite crystals in chains within their
cells to make compasses, which help the bacteria locate
sources of food and energy. Magnetite (Fe3O4) is produced
inorganically on Earth, but the magnetite crystals produced
by magnetotactic bacteria are very different -- they are
chemically pure and defect-free, with distinct sizes and
shapes.

Four of the MAB biosignature properties relate to the
external physical structure of the magnetite crystals, while
another refers to their internal structure and another to
their chemical composition.

In their earlier studies, the researchers found that
approximately one-quarter of the nanometer-sized magnetite
crystals in ALH84001 had remarkable physical and chemical
similarities to magnetite particles produced by a bacteria
strain on Earth called MV-1. This is the first time, however,
that any researcher has used the full MAB range of
biosignature properties to compare the proposed bacteria-
produced crystals in Mars meteorite ALH84001with the
bacteria-produced crystals from Earth and with the other
magnetites in the meteorite.

The comparison between the proposed bacteria-produced
crystals in the meteorite and crystals known to be produced
by Earth-bacteria MV-1 is striking and provides strong
evidence that these crystals were made by bacteria on Mars.

The fact that Mars Global Surveyor data suggest that early
Mars had a magnetic field is consistent with a reason why
Mars would have magnetotactic bacteria. "Our best working
hypothesis is that early Mars supported the evolution of
bacteria that share several traits with magnetotactic
bacteria on Earth, most notably the MV-1 group," said Simon
Clemett, a coauthor of the paper at Johnson.

Mars has long been understood to provide the sources of light
and chemical energy sufficient to support life, but in 2001
the Mars Global Surveyor spacecraft observed magnetized
stripes in the crust of Mars, which showed that a strong
magnetic field existed in the planet's early history, about
the same time as the carbonate containing the unique
magnetites in ALH84001 was formed.

In June, researchers using the Mars Odyssey spacecraft
announced that they had found water ice under the surface of
Mars. These attributes, coupled with a carbon dioxide-rich
atmosphere, would have provided the necessary environment for
the evolution of microbes similar to the fossils found in
ALH84001.

"We believe this latest study proves that the magnetites in
ALH84001 can be best explained as the products of multiple
biogenic and inorganic processes that operated on early
Mars," Thomas-Keprta said.

An international team of nine researchers collaborated on the
three-year study. The team, led by Thomas-Keprta of Lockheed
Martin at Johnson Space Center, was funded by the NASA
Astrobiology Institute. Co-authors of the study are Clemett
and Susan Wentworth of Lockheed Martin at JSC; Dennis
Bazylinski of Iowa State University (funded by the National
Science Foundation); Joseph Kirschvink of the California
Institute of Technology in Pasadena; David McKay and Everett
Gibson of JSC; Hojatollah Vali of McGill University in
Canada; and Christopher Romanek of the Savannah River Ecology
Laboratory.

For a more technical discussion of this latest publication
please visit the following Web site:

<a href="http://ares.jsc.nasa.gov/astrobiology/biomarkers/recentnews.h" target="_blank">http://ares.jsc.nasa.gov/astrobiology/biomarkers/recentnews.h</a>
tml

-end-

Excuse the goofy formatting.

Dr.GH · 08-02-2002, 08:00 PM

Interestin'

More and more I am inclined to the notion that "life is easy." Living can be hard, but the start is not a problem.

ID has really nothing but the OOL to grasp inorder to keep their later day crationist affair afloat.

beausoleil · 08-02-2002, 10:25 PM

I've seen this evidence presented several times at conferences over the last few years, and the debate still rages. Some of it is down to morphology - you'd be surprised how hard it seems to be to decide exactly what shape a magnetite cryslal that size is. Then there are arguments about how well studied non-biological natural magnetite crystals are (goes to the 'no non-biological magnetite has these properties' bit). One competing explanation is that these grew as the siderite (iron carbonate) in the globules decomposed - it seems unclear how that affects the morphology. If they've convinced the rest of the mineralogists, I've not heard, and I'm suspicious that this has appeared in a microbiology journal rather than a mineralogical publication. (But I'm suspicious by nature!)

At the last LPSC conference it struck me that astrobiology is still a bandwagon with no samples and too much money being thrown at it.

Utnapishtim · 08-03-2002, 10:40 AM

That link of yours doesn't appear to work. Here's one that should: <a href="http://ares.jsc.nasa.gov/astrobiology/biomarkers/recentnews.html" target="_blank">right here</a>

[ August 03, 2002: Message edited by: Utnapishtim ]</p>

Dr.GH · 08-03-2002, 11:28 AM

beausoleil

I think that there is more than a 'grain' of truth to what you say.

Starboy · 08-03-2002, 11:47 AM

I concur. I went to the first case for Mars conference so long ago. Chris McKay is an old friend of mine. The Martians have a definite aura of "keep the faith".

Starboy

[ August 03, 2002: Message edited by: Starboy ]</p>

Valentine Pontifex · 08-03-2002, 03:18 PM

Quote:

"This means that one-quarter of the magnetite
crystals embedded in the carbonates in Martian meteorite
ALH84001 require the intervention of biology to explain their
presence."

NASA is sounding more and more like William Dembski all the time. This is nothing more than an argument from ignorance: we don't know what caused it therefore life caused it. "QED."

ps418 · 08-03-2002, 04:23 PM

Quote:

Originally posted by LordValentine:
<strong>

NASA is sounding more and more like William Dembski all the time. This is nothing more than an argument from ignorance: we don't know what caused it therefore life caused it. "QED."</strong>

I'd have to disagree. The articles claiming that some of the magnetite grains in ALH84001 are probable biogenic claim as much because (some of) the grains supposedly meet positive criteria for biogenicity [the "Magnetite Assay for Biogenicity"], not simply because they display features not known from abiogenic magnetite. I think the case for their being biogenic is far from conclusive, and their MAB is probably incomplete, but their arguments arent purely eliminative like Dembski's.

Patrick

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08-02-2002, 08:00 PM	#2
Dr.GH Veteran Member Join Date: Jul 2001 Location: Dana Point, Ca, USA Posts: 2,115	Interestin' More and more I am inclined to the notion that "life is easy." Living can be hard, but the start is not a problem. ID has really nothing but the OOL to grasp inorder to keep their later day crationist affair afloat.

08-02-2002, 10:25 PM	#3
beausoleil Senior Member Join Date: May 2002 Location: US and UK Posts: 846	I've seen this evidence presented several times at conferences over the last few years, and the debate still rages. Some of it is down to morphology - you'd be surprised how hard it seems to be to decide exactly what shape a magnetite cryslal that size is. Then there are arguments about how well studied non-biological natural magnetite crystals are (goes to the 'no non-biological magnetite has these properties' bit). One competing explanation is that these grew as the siderite (iron carbonate) in the globules decomposed - it seems unclear how that affects the morphology. If they've convinced the rest of the mineralogists, I've not heard, and I'm suspicious that this has appeared in a microbiology journal rather than a mineralogical publication. (But I'm suspicious by nature!) At the last LPSC conference it struck me that astrobiology is still a bandwagon with no samples and too much money being thrown at it.

08-03-2002, 10:40 AM	#4
Utnapishtim Regular Member Join Date: Feb 2002 Location: Vancouver, BC Posts: 330	That link of yours doesn't appear to work. Here's one that should: <a href="http://ares.jsc.nasa.gov/astrobiology/biomarkers/recentnews.html" target="_blank">right here</a> [ August 03, 2002: Message edited by: Utnapishtim ]</p>

08-03-2002, 11:28 AM	#5
Dr.GH Veteran Member Join Date: Jul 2001 Location: Dana Point, Ca, USA Posts: 2,115	beausoleil I think that there is more than a 'grain' of truth to what you say.

08-03-2002, 11:47 AM	#6
Starboy Banned Join Date: Jun 2002 Location: Tallahassee, FL Reality Adventurer Posts: 5,276	I concur. I went to the first case for Mars conference so long ago. Chris McKay is an old friend of mine. The Martians have a definite aura of "keep the faith". Starboy [ August 03, 2002: Message edited by: Starboy ]</p>

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