Mars Sedimentary Rocks Suggest Fossil Trove, Life
By John Roach <br>December 8, 2000
Exotic microbes, four-eyed fish, and other aquatic creatures of and beyond the human
imagination may have swum in lakes on Mars 4.3 to 3.5 billion years ago. Their fossils
could be preserved in the sedimentary rock left behind.
<p>
That is the vision painted by pictures of the red planet captured by a camera aboard
NASA's Mars Global Surveyor spacecraft. The images, published and described in the
December 8 issue of the journal <em>Science,</em> suggest that Mars may have been a
land of lakes.
<p>
"On Earth, sedimentary rocks preserve the surface history of our planet, and within that
history the fossil record of life," said Michael Malin, principal investigator for the camera
aboard the Mars Global Surveyor. "It is reasonable to look for evidence of past life on
Mars in these remarkably similar sedimentary layers."
<p>
<b>SEDIMENT DEPOSIT</b>
<p>
Sedimentary deposits can be produced in a variety or ways, from water and wind erosion
to volcanic eruptions and meteorite bombardment. The question of which of these
processes led to the apparent sedimentary layers on Mars remains open, as does the
question of whether they contain fossils.
<p>
Malin and colleague Ken Edgett at Malin Space Science Systems in San Diego,
California, say the prevalence of sedimentary outcrops with basin-like features suggests
they were deposited by water, most likely in lakes that formed within craters and chasms.
<p>
"This is an additional confirmation of the view that Mars was warm and wet in the distant
past," said Robert Zurbin, president of the Mars Society, an Indian Hills, Colorado, nonprofit organization dedicated to exploration and human settlement of the red planet.
<p>
<b>LIFE ON MARS</b>
<p>
The recent flood of evidence that Mars was once a wet place, including a June
announcement that water likely flowed on the planet's surface within the past few million
years, has bolstered beliefs that life existed and may still exist on the planet.
<p>
On Earth, life exists wherever there is water. Scientists argue that if water persisted on
Mars, there is no reason to believe that it would not have had the chemistry needed for
life.
<p>
<b>MISSION TO MARS</b>
<p>
"If we can go to Mars and find fossils in these sediments, then we have proven that life is
a characteristic feature of the Universe," said Zurbin. "If we could sample that life, then
we could see what Martian life is and was like. We could examine its genome and by
doing so we could see what the laws of life are."
<p>
While the Mars Society believes that the technical capacity exists today to launch a
manned-mission to Mars by 2008, NASA is expected to take a more cautious approach.
<p>
In 2003 the space agency is scheduled to launch twin rovers to study the ancient climate
and possibility of water on Mars. A rover that will collect samples of rock and soil and
return them to Earth is not expected to launch until at least 2011.
<li> Images of Mars taken by a camera aboard the Mars Global Surveyor spacecraft
suggest that Mars may have been a land of lakes.
<li> The images add to a flood of recent evidence that indicates Mars was warm and wet
in the distant past.
<li> Scientists argue that if water persisted on Mars, there is no reason to believe that the
planet would not have harbored the chemistry needed for life.
<li> A rover that will collect samples of Martian rock and soil and return them to Earth is
not expected to launch until at least 2011.
Exotic microbes, four-eyed fish, and other aquatic creatures of and beyond the human
imagination may have swum in lakes on Mars 4.3 to 3.5 billion years ago. Their fossils
could be preserved in the sedimentary rock left behind.