[meteorite-list] Key To Life On Mars May Be In Sudbury

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:06:17 2004
Message-ID: <200211261720.JAA20324_at_zagami.jpl.nasa.gov>


Key To Life On Mars May Be In Sudbury

NASA is studying some of the most inhospitable places on Earth -- like
the crater in Sudbury -- in a bid to understand the red planet, writes
Joanne Laucius.
Joanne Laucius
The Ottawa Citizen
November 26, 2002

NASA wants to know what the Sudbury crater has to tell scientists about
life on Mars.

Researchers from the U.S. space agency are probing the most inhospitable
places on Earth in the hopes they will find clues about how lifeforms could
survive another inhospitable place -- Mars.

They are studying how lifeforms adapted to survive in the Siberian
permafrost, the arid valleys of Antarctica and a dormant volcano
in the Chilean Andes. And they're hoping that Canada's ancient
Sudbury crater also has some secrets to reveal.

There are hundreds of "impact craters" on Mars, created by asteroids and
comets that struck the red planet millions or billions of years ago. By
studying Sudbury's own impact crater, a team of six scientists, including
Ottawa's Doreen Ames, are hoping they can learn how life might thrive after a
planet gets smacked with a resounding extraterrestrial blow.

The Sudbury crater was created 1.85 billion years ago, likely when a comet
slammed into the Earth. That impact started a chain of events that would
last for tens of thousands of years, said Ms. Ames, a geologist with Natural
Resources Canada.

The crater is 200 kilometres in diameter and about a kilometre deep. The
impact exposed the rich veins of ore that make Sudbury famous. It also created
hydrothermal systems much like those that still exist deep under the sea and
near volcanoes.

When an asteroid or comet hits the Earth, it melts rock and produces a
red-hot sheet of lava. Over thousands of years, a muddy lake forms.

Like a pot of boiling water, a hydrothermal system has heat coming from below
-- the magma under the ground. The system also produces convection, pulling
water down through the rocks and generating nutrients.

It is a warm habitat -- even scalding. But some parts of the hydrothermal
system would be cool enough to support primitive life forms such as bacteria.

Scientists are searching for fossil evidence of bacteria in rock samples. If
they find that evidence in the Sudbury crater, it would help point NASA in
the right direction when it sends a robot rover to the surface of Mars.

"It's a good place to look for potential life," said Ms. Ames, who has been
studying the Sudbury crater for about 10 years. "Mars went through an early
bombardment. There are hundreds if not thousands of craters on Mars. Some
are larger than the ones on Earth."

It is unlikely that hydrothermals provided the conditions for the genesis of
life, said project leader Kevin Pope. "We're not really looking for the origin
of life, although some people have suggested that hydrothermals might have
been candidates for that the happen," he said.

Impacts may not have created life, but they did change it. Mass extinctions
are associated with impacts, including the one that created Mexico's Chicxulub
crater 65 million years ago and wiped out the dinosaurs.

On the other hand, impacts may not have been a bad thing for microbes. There was
primitive life on Earth long before the comet hit Sudbury. The impact may have
affected its evolutionary path.

"You take a big right angle turn after an impact," said Ms. Ames.

The Sudbury crater is one of the largest craters on Earth. It is also the
best-preserved, although it has been eroded over millions of years, layers of
sediment have been deposited on top of it and tectonic forces have moulded it
like plasticine, distorting its original round shape until it now appears to
be an oval with one flattened side.

Still, the Sudbury crater is better exposed than Chicxulub, which is covered
by other rocks. It is also better preserved than the Vredefort crater in
South Africa, which is so badly eroded there's hardly anything left.

Craters on Earth have been buried and distorted by tectonic activity. On Mars,
the craters are still very clearly defined, said Mr. Pope.

The project is only about a year-and-a-half old. But so far, scientists have
been disappointed by what they've seen -- or not -- under the microscope. So
far, they have found no fossil evidence of ancient bacteria.

But researchers have to get a better idea of where to look, said Mr. Pope.
"First, you have to identify parts of the hydrothermal system that would be
cool enough to have have life in them."
Received on Tue 26 Nov 2002 12:20:17 PM PST

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