Wednesday August 7 2:44 PM EDT
Debate on Evidence of Ancient Life on Mars
HOUSTON (Reuter) - The discovery that life apparently existed on Mars
was hailed Wednesday as the
greatest discovery of this century, one that could have far-reaching
effects on philosophy, religion and
science.
``This changes our view of ourselves, it changes our view of the
universe,'' Louis Friedman of The Planetary
Society said.
Planetary scientists were unusually enthusiastic about the evidence,
laboriously put together by electron
microscopic analysis of fossils dating back billions of years. One
scientist called the discovery ``unequivocal''
and another said it was the most stunning scientific find in decades.
NASA scientists planned to disclose at a press conference in Washington
at 1 p.m. EDT Wednesday more
details of their discovery of evidence of single-cell, bacteria-like
organisms inside an ancient Martian
meteorite that plunged to Earth more than 13,000 years ago.
For the past two years, a team of NASA and Stanford University
scientists has been examining a 4.2 pound,
potato-sized meteorite for traces of organic molecules and carbon
compounds, the building blocks of life on
Earth.
The rock formed under the surface of Mars about 4.5 billion years ago,
the scientists said. Between 3.6
billion and 4 billion years ago, water penetrated fractures in the rock
and deposited carbonate materials.
The scientists said they believe living organisms may have been involved
in the formation of the carbonate
and some of the microscopic organisms may have fossilized in the rock.
Inside the microscopic globs of carbonate, the scientists said they
found detectable amounts of polycyclic
aromatic hydrocarbons, mineral compounds associated with microscopic
organisms and possible
microscopic fossils.
``It is not any one finding that leads us to believe that this is
evidence of past life on Mars. Rather, it is a
combination of many things that we have found,'' NASA scientist David
McKay said. ``The relationship of
all these things in terms of location -- within a few hundred
thousandths of an inch of one another -- is the
most compelling evidence.''
The scientists said they expected their startling findings to come under
attack by the international scientific
community and they welcomed the controversy.
``We don't claim that we have conclusively proven it. We are putting
this evidence out to the scientific
community for other investigators to verify, enhance, attack -- disprove
if they can,'' planetary scientist
Everett Gibson said in a statement released by Stanford University.
NASA administrator Daniel Goldin made it clear the discovery bore no
relation to science fiction or
Hollywood versions of life's beginnings in space.
``I want everybody to know that we are not talking about 'little green
men,''' he said. ``These are extremely
small, single-cell structures that somewhat resemble bacteria on Earth.
There is no evidence or suggestion
that any higher life form ever existed on Mars.''
The possible fossils included egg-shaped and tubular structures so small
they can be seen only under an
electron microscope. ``The structures are strikingly similar to
microscopic fossils of the tiniest bacteria found
on Earth,'' the Stanford statement said.
The meteorite was probably blasted off the surface of Mars 16 million
years ago after a massive comet or
asteroid struck the now-dead planet, the NASA researchers said in a
draft article of their findings to be
published in Science magazine.
After floating in space for millions of years the meteorite plunged to
Earth, where it was discovered in a
frozen field in Antarctica in 1984. The make-up of the meteorite known
as ALH84001 matches the chemical
compositions of the surface of Mars measured by the Viking spacecraft
that landed on the planet in 1976,
the scientists said.
The NASA researchers said it was unlikely the evidence of living
organisms was deposited deep inside
fissures of the rock after it entered the Earth's atmosphere but they
expected that and other facets of their
research to be challenged.
``It is very difficult to prove life existed 3.6 billion years ago on
Earth, let alone on Mars,'' said Stanford
chemist Richard Zare, a member of the NASA research team.
The scientists plan to publish their findings in the Aug. 16 issue of
Science magazine and will discuss their
findings publicly for the first time Wednesday.