[meteorite-list] ALH84001-- the death of it's rumors greatly exaggerated

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Wed, 25 Nov 2009 11:24:21 -0500
Message-ID: <pbmqg5dtilqfa2tc5o7v5lp81qeepeq0uc_at_4ax.com>

Martian meteorite surrenders new secrets of possible life
BY CRAIG COVAULT
SPACEFLIGHT NOW
Posted: November 24, 2009

Compelling new data that chemical and fossil evidence of ancient microbial life
on Mars was carried to Earth in a Martian meteorite is being elevated to a
higher plane by the same NASA team which made the initial discovery 13 years
ago.

Sources tell Spaceflight Now that the new data are providing a powerful new case
for the Allen Hills Meteorite to have carried strong evidence of Martian life to
Earth -- evidence that is increasingly standing up to scrutiny as new analytical
tools are used to examine the specimen.
 
The latest findings are the product of new research using more advanced High
Resolution Electron Microscopy than was in existence when the initial findings
were made and announced by NASA and the White House in 1996.

Those laboratory sensors are being focused directly on carbonate discs and
associated tiny magnetite crystals present inside the meteorite Allen Hills ALH
84001.

Sources tell Spaceflight Now that the more detailed data on magnetite crystals
and carbonate discs now available largely counter a wide range of opposing
theories as to why the finding should not be supported as biological in origin.

Now, 13 years after the Martian meteorite life story emerged, the science team
finally feels vindicated. Their data shows the meteorite is no smoking gun but
is full of evidence that supports the existence of life on the surface of Mars,
or in subsurface water pools, early in the planet's history.

The new data are expected to be addressed publicly within days by NASA
Headquarters in Washington, where they could become part of the political debate
on future NASA mission directions.
 
The findings have already emerged within the scientific community in the form of
an extremely detailed 46-page paper provided to Spaceflight Now on new Mars life
findings.

The document is part of the November issue of the respected journal Geochimica
et Cosmochimica Acta, the journal of the Geochemical and Meteoritic Society.

Its authors are Kathie Thomas-Keprta, Simon Clement, David McKay (who led the
original team), Everett Gibson and Susan Wentworth, all of the Johnson Space
Center. Keprta is the principal author.

Although led by a Johnson Space Center team, the additional evidence for Martian
life in the Allen Hills meteorite has been an open topic for the last several
weeks in astrobiology division halls at the NASA Ames Research Center near San
Francisco and at the Jet Propulsion Laboratory, Pasadena. It's hot news.

The new work centers on so-called magnetic bacteria that on Earth, and
apparently Mars as well, leave distinctively-shaped remnants in the rock. In
addition the features test with a high chemical purity more like a biological
feature than geological.

These are just like the magnetite-related life forms found in the meteorite
believed to represent Martian life forms, says Dr. Dennis Bazylinski, who peer
reviewed the new findings. He also studies such Earth life forms in his
laboratory at the University of Nevada at Las Vegas.

"I think the paper is really excellent. I have no trouble with the paper,"
Bazylinski told Spaceflight Now.

"I work on magnetic bacteria, and one indication there was life on ancient Mars
are these particular magnetite crystals in the meteorite that look like they
came out of magnetic bacteria. At first [when the data was reported in 1996], I
thought there might have been an error. I have no doubt about that now. I know
there is no error," Bazylinski stressed.

"The big question is can these things [magnetite crystals] be reliable magneto
fossils, and that is a matter of debate.

"But it turns out that the magnetic bacteria make some very unique shapes of
magnetite crystals. And one of the organisms we work with on Earth makes
particles that look virtually identical to what we see from Mars in the
meteorite."


Scientists say micro-fossils of bacteria are nested with tiny crystal magnetites
that provide additional evidence for life. Credit: NASA
 
Another noted researcher in this field who has peer reviewed the new paper, and
is supportive of the findings, is Dr. Joseph L. Kirschvink of CalTech.

Unfortunately, as the new information was about to be announced by NASA, he was
on a freighter hoping to survive a crossing the treacherous Drake Passage
between Cape Horn and Antarctica, where he will do studies during the Antarctic
summer.

But posted on his Web site is a message about the Allen Hill Meteorite work:

"One of the most interesting debates involving magneto fossils concerns their
use by Dave McKay [and the Mars meteorite team] as biomarkers in the ALH84001
Martian meteorite.

"This is clearly the most interesting and innovative use of potential
magnetosomes as a biomarker," said Kirschvink.

For years after the Martian meteorite data were first presented, opponents of
the life theory argued that the same shaped features and associated chemical
purity was just as likely caused by a thermal/shock event that blasted the
material off Mars in the first place.

But research led by Kathie Thomas-Keprta of the original Allen Hills team has
now proven the thermal theory is invalid, strengthening the team's argument that
the "magnetic bacteria" features found in the meteorite were indeed formed by
biologic activity on Mars and not some non-biologic thermal event.

Although not a smoking gun, the new findings considerably strengthened the Mars
life arguments that have been hotly and passionately debated for a decade, given
that the discovery of life on Mars is the Holy Grail of science.


The meteorite was blasted off Mars by a different rock that impacted with an
oblique angle (far right) and launched ejecta skyward. Credit: NASA
 
That was made clear in the August 7, 1996, comments by President Clinton during
the White House announcement of the initial findings, now considerably
strengthened by Keprta and the rest of her team after years of hostile
criticism.

"It is well worth contemplating how we reached this moment of discovery," said
President Clinton.

"More than 4 billion years ago this piece of rock was formed as a part of the
original crust of Mars. After billions of years, it was blasted from the surface
and began a 16 million year journey through space that would end here on Earth.

"It arrived in a meteor shower 13,000 years ago. And in 1984, an American
scientist on an annual U.S. government mission to search for meteors on
Antarctica picked it up and took it to be studied. Appropriately, it was the
first rock to be picked up that year -- rock number 84001," said Clinton.

"Today, rock 84001 speaks to us across all those billions of years and millions
of miles."

"It speaks of the possibility of life. If this discovery is confirmed, it will
surely be one of the most stunning insights into our universe that science has
ever uncovered. Its implications are as far-reaching and awe-inspiring as can be
imagined. Even as it promises answers to some of our oldest questions, it poses
still others even more fundamental," Clinton said.

"We will continue to listen closely to what it has to say," the president said.

That is exactly what the NASA team has done over the last decade. And the
message that is now coming clearer from Allen Hills ALH84001, 13 years after its
initial analysis, is the more you dig into its past the more you will see that
past included life on early Mars.
Received on Wed 25 Nov 2009 11:24:21 AM PST