| Life on Mars! |
Date: Tue, 6 Aug 1996 16:50:22 -0400
From: NASANews@luna.osf.hq.nasa.gov (NASA HQ Public Affairs Office)
To: press-release-net@venus.hq.nasa.gov
Subject: Statement from Daniel S. Goldin, NASA Administrator
Sender: owner-press-release@venus.hq.nasa.gov
Content-Length: 1458
Laurie Boeder
Headquarters, Washington, DC
August 6, 1996
(Phone: 202/358-1898)
RELEASE: 96-159
STATEMENT FROM DANIEL S. GOLDIN, NASA ADMINISTRATOR
"NASA has made a startling discovery that points to the
possibility that a primitive form of microscopic life may
have existed on Mars more than three billion years ago. The
research is based on a sophisticated examination of an ancient
Martian meteorite that landed on Earth some 13,000 years ago.
The evidence is exciting, even compelling, but not
conclusive. It is a discovery that demands further
scientific investigation. NASA is ready to assist the
process of rigorous scientific investigation and lively
scientific debate that will follow this discovery.
I want everyone to understand that we are not talking
about 'little green men.' 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.
[JJM : He could have gotten the colour of the "little green men"
right at least :) ]
The NASA scientists and researchers who made this
discovery will be available at a news conference tomorrow to
discuss their findings. They will outline the step-by-step
"detective story" that explains how the meteorite arrived
here from Mars, and how they set about looking for evidence
of long-ago life in this ancient rock. They will also
release some fascinating images documenting their research.
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Chemical analysis of meteorite suggests life on Mars
WASHINGTON - A meteorite that fell to Earth after possibly
being ejected from Mars may bear chemical evidence that life once
existed on that planet, NASA officials said Tuesday.
The officials confirmed that a report in Space News, a weekly
publication on the space program, is "essentially correct" about
the meteorite containing possible indications of life on Mars.
Another source said the study found traces of magnetite, a mineral that
can be associated with bacterial action, but that processes
other than life can also produce magnetite.
NASA spokesman James Hartsfield of the Johnson Space Center in Houston
confirmed that research sponsored by JSC concluded that a meteorite called
ALH 84001 is 4 billion to 4.5 billion years old and that the stony object
is thought to have been blasted away from Mars when asteroids battered
the red planet.
He confirmed that some researchers studying the meteorite concluded it
bore chemical evidence of past biological activity on
Mars.
Don Savage, a spokesman at NASA's Washington headquarters, also
confirmed the report was correct. A source at Science
magazine said the publication had received a paper describing the study
and that the paper had been peer-reviewed and prepared
for publication.
Earlier research has confirmed that material has fallen to Earth from
both Mars and the Moon after being knocked into space by
impacts. Some of the material is thought to have drifted in space for
millions of years before reaching Earth.
By The Associated Press
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American Association for the Advancement of Science News Release
Signs of Past Life on Mars?
Organic Compounds and Possible Biological Features
Found in Martian Meteorite,
Featured in 16 August 1996 Science
Washington, DC - Ever since scientists learned that water once flowed on
Mars, they've wondered whether life might also have flourished on the
apparently now-dead planet. In the 16 August issue of Science, McKay et
al report the first identification of organic compounds in a Martian
meteorite. The authors further suggest that these compounds, in
conjunction with a number of other mineralogical features observed in
the rock, may be evidence of ancient Martian microorganisms.
The paper's authors are David S. McKay and Everett K. Gibson, Jr., of
NASA's Johnson Space Center in Houston, TX; Kathie L. Thomas-Keprta of
Lockheed Martin in Houston, TX; Hojatollah Vali of McGill University in
Montreal, Quebec; Christopher S. Romanek of the University of Georgia's
Savannah River Ecology Laboratory in Aiken, SC; and Simon J. Clemett,
Xavier D.F. Chllier, Claude R. Maechlin, and Richard N. Zare of Stanford
University in Stanford, CA.
Organic (complex, carbon-based) molecules are the requisite building
blocks of life on Earth. The authors looked for signs of such molecules
and other mineralogical and textural indications of past life within the
pore space and fractures of meteorite Allan Hills 84001 (ALH84001), one
of only 12 meteorites identified as having come from Mars. ALH84001 is
the oldest of the Martian dozen, having crystallized from molten rock
about 4.5 billion years ago, early in the planet's evolution, and it is
the only Martian meteorite to contain significant carbonate minerals.
(The carbonates formed sometime after the rock, perhaps about 3.6
billion years ago.)
About 15 million years ago, a major asteroid impact on Mars threw
ALH84001 into space, where it eventually fell onto an ice field in
Antarctica about 13,000 years ago. ALH84001, which shows little evidence
of terrestrial weathering, was discovered by meteorite-hunting
scientists in 1984 and only recently identified at Martian.
ALH84001 is riven with tiny fractures resulting primarily from impacts
that occurred while the rock was on Mars. The secondary carbonates
formed along with some of these fractures. The Science authors
prepared thin sample sections that included these pre-existing
fractures, and found on their surfaces a clear and distinct distribution
of polycyclic aromatic hydrocarbons (PAHs), organic molecules containing
multiple connected rings of carbon atoms -- the first organic molecules
ever seen in a Martian rock. A variety of contamination checks and
control experiments indicated that the organic material was indigenous
to the rock and was not the result of terrestrial contamination. For
example, the authors noted that the concentration of PAHs increases
inward, whereas terrestrial contamination likely would have resulted in
more PAHs on the exterior of the rock.
The big question is: where did the PAHs come from?
It is thought that PAHs can form one of two ways: non-biologically,
during early star formation; or biologically, through the activity of
bacteria or other living organisms, or their degradation
(fossilization). On Earth, PAHs are abundant as fossil molecules in
ancient sedimentary rocks, coal and petroleum, the result of chemical
changes that occurred to the remains of dead marine plankton and early
plant life. They also occur during partial combustion, such as when a
candle burns or food is grilled.
To address the origin of these PAHs, the authors examined the chemistry,
mineralogy, and texture of carbonates associated with PAHs in the
Martian meteorite. Under the transmission electron microscope, the
carbonate globules were seen to contain fine-grained magnetite and
iron-sulfide particles. From these and other analyses, the authors
developed a list of observations about the carbonates and PAHs that,
taken individually, could be explained by non-biological means. However,
as they write in their Science article, "when considered collectively
... we conclude that [these phenomena] are evidence for primitive life
on early Mars." Some of their observations are as follows:
* The higher concentrations of PAHs were found associated with the
carbonates.
* The carbonates formed within the rock fissures, about 3.6 billion
years ago, and are younger than the rock itself.
* The magnetite and iron-sulfide particles inside the carbonate globules
are chemically, structurally and morphologically similar to magnetosome
particles produced by bacteria on Earth.
* High-resolution scanning electron microscopy revealed on the surface
of the carbonates small (100 nanometers) ovoids and elongated features.
Similar textures have been found on the surface of calcite concretions
grown from Pleistocene groundwater in southern Italy, which have been
interpreted as representing nanobacteria.
* Some earlier reports had suggested that the temperature at which the
ALH84001 carbonates formed was as high as 700' C -- much too hot for any
kind of life. However, the isotopic composition of the carbonates, and
the new data on the magnetite and iron-sulfide particles, imply a
temperature range of 0' to 80'C, cool enough for life.
* The magnetite -- a mineral which contains some ferric (Fe3+) iron,
perhaps indicating formation by oxidation (the addition of oxygen) --
and iron sulfide -- a mineral that can be formed by reduction (the loss
of oxygen) -- were found in close proximity in the Martian meteorite. On
Earth, closely associated mineralogical features involving both
oxidation and reduction are characteristic of biological activity.
Science is the official journal of the American Association for the
Advancement of Science (AAAS) in Washington, DC, the world's largest
general science organization.
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The Electronic Telegraph
UK News Wednesday August 7 1996
The bug that fell to Earth
By Roger Highfield, Science Editor
A METEORITE that fell to Earth after possibly being ejected from Mars may bear
the first traces of life elsewhere in the universe, according to new research.
If confirmed, the discovery will back the suspicion of many scientists that
the kind of self replicating chemical processes that can cross the watershed
between the inanimate and the living are more common than we think, making
alien life inevitable.
Monica Grady, of the Natural History Museum in London, said that the fossil
evidence, if correct, would be among the most sensational in history.
"It's entirely possible that very, very primitive organisms might have
arisen," she said. "I'm not talking about ammonites or corals or anything like
that, but something incredibly primitive such as micro-fossils from highly
primitive organisms. It's absolutely fascinating to find these."
The astronomer Patrick Moore said that more evidence was needed before jumping
to conclusions. "For a long time we have known there was running water on Mars
because we have seen the evidence of it. There has long been the theory that
life started there but died out. For all that, I still need to be convinced by
hard evidence.
"It is still not confirmed that these meteorites definitely came from Mars,
although they are very similar in composition to what we believe their make-up
would be if they were."
This year has seen the 20th anniversary of the Viking mission to Mars, a
mission that failed to find evidence of living things and led subsequent
meetings of "exobiologists" to the disappointing conclusion that conditions on
the surface of the Red Planet were not conducive to life.
That has changed with the theory that conditions for life could have emerged
on Mars between three billion and four billion years ago, when the planet was
warmer and wetter.
The meteorite is the oldest of these, having crystallised from molten rock
early in the planet's evolution, about 4.5 billion years ago
The results will be published in the journal Science by Drs David McKay and
Everett Gibson of NASA's Johnson Space Centre in Houston, working with
colleagues at Lockheed Martin, McGill University in Montreal, University of
Georgia in Aitken, South Carolina, and Stanford University in California.
Given that the tell-tale clues occur in the same sites within the meteorite,
"when considered collectively . . . we conclude that [these phenomena] are
evidence for primitive life on early Mars," they write.
Organic (carbon-based) molecules are the requisite building blocks of life on
Earth. The team looked for signs of them and other indications of past life
within the fractures of a meteorite called ALH 84001, one of only a dozen
thought to have come from Mars.
The meteorite is the oldest of these, having crystallised from molten rock
early in the planet's evolution, about 4.5 billion years ago. Significantly, it
is the only Martian meteorite to contain carbonate minerals, which formed some
time after the rock, about 3.6 billion years ago.
About 15 million years ago, a major asteroid impact on Mars threw ALH 84001
into space, and it eventually fell on to an ice field in Antarctica about
13,000 years ago. It was discovered by meteorite hunters in 1984.
The meteorite is riven with minute fractures - formed primarily from impacts
on Mars - and secondary carbonates formed along them. The team prepared thin
samples that included these fractures, and found on their surfaces a clear and
distinct distribution of polycyclic aromatic hydrocarbons (PAHs), organic
molecules containing multiple connected rings of carbon atoms - the first
organic molecules ever seen in a Martian rock.
"Most of us here believe that there is a significant probability that there
was life on Mars"
It is possible that PAHs can form during early-star formation but they can
also be formed by bacteria or other living organisms, or their fossilisation
(they are as abundant as fossil molecules in ancient sedimentary rocks).
To pin down the origin of the PAHs, the team examined the chemistry,
minerology and texture of the carbonates from the Martian meteorite. And the
following factors convinced them that primitive life was responsible:
The highest concentrations of the PAHs were found with the carbonates;
The carbonates formed in the rock fissures about 3.6 billion years ago, and are
younger than the rock;
The carbonate globules are similar to those produced by bacteria in the
laboratory and in a freshwater pond;
The temperature at which the carbonates formed was once thought too hot for life
- around 700 deg C - but new data suggests they could have formed between 0 deg
C and 80 deg C, easily cool enough for life;
Magnetite and iron sulphide particles inside the carbonate globules are
chemically, structurally and, in terms of appearance, similar to "magnetosome
particles", which are produced by bacteria on Earth;
Electron microscopy revealed on the surface of the carbonates small ovoids and
elongated features. Similar textures found in southern Italy have been
interpreted as "nanobacteria";
The particles of magnetite, a mineral which contains some ferric iron, perhaps
indicating formation by the addition of oxygen and iron sulphide - a mineral
that can be formed by the loss of oxygen - were found in close proximity in
the Martian meteorite.
On Earth, closely associated mineralogical features involving both these
processes - oxidation and reduction - are characteristic of biological
activity.
The news will not surprise workers in the field. "Most of us here believe that
there is a significant probability that there was life on Mars," Prof Malcolm
Walter of Macquarie University, Australia, told an international meeting
organised by the charitable Ciba Foundation earlier this year in London.
The belief that life might be able to exist on Mars has also been supported by
studies of microbes thriving in extreme conditions on Earth. Last October, the
Pacific Northwest Laboratory found primitive bacteria tough enough to survive
on the Red Planet. Called hyperthermophiles, these organisms can live and
multiply without oxygen or light in extreme temperatures - the microbes derive
their nutrition from water and rock.
When the atmosphere of the planet was lost, more than two billion years ago,
Mars cooled and its surface dried to leave valleys, channels and polar ice
caps. One idea is that life would have taken a dive under the surface, tracking
the habitable zone of liquid water.
To test this theory, the first in a series of missions will be launched in
December to study a site where rapid mineral precipitation could have entombed
Martian organisms.
In July 1997 a probe will land on the planet's surface, which is below
freezing point. It will release a tethered robot which will analyse the
terrain. However, conclusive evidence of traces of life might have to wait
until 2005, when a mission will attempt to return the samples to Earth.
Electronic Telegraph is a Registered Service Mark of Telegraph Group Limited
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