Subject: Life on Mars part two
From: m.pallen@ic.ac.uk (Mark Pallen)
Date: 12 Aug 1996 04:15:04 -0700
Here's the second part of Marsbugs (Netscape wouldn't let me send it
all in one go.)
Date: 8 Aug 1996 20:32:54 -0500
From: Julian Hiscox <julian_hiscox@micro.microbio.uab.edu>
Subject: Marsbugs. V.3. N.8. Part 2.
To: "Dr. Julian and Melissa Hiscox" <marsgene@aol.com>
Subject: Time:
8:31 PM
OFFICE MEMO Marsbugs. V.3. N.8. Part 2. Date:
8/8/96
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SEARCH FOR PAST LIFE ON MARS: POSSIBLE RELIC BIOGENIC ACTIVITY
IN MARTIAN METEORITE ALH84001
David S. McKay, Everett K. Gibson, Kathie L. Thomas-Keprta,
Hojatollah Vail, Christopher S. Romanek, Simon J. Clement, Xavier
D. F. Chillier, Claude R. Maechling, and Richard N. Zare.
[This message was passed along the internet, author unknown, and
is of interest to the current debate about the possible origin
and evolution of life on Mars. If we are infringing upon
someone's copyright, it is not our intention to do so, and we
apologize.]
ALH84001 is a martian meteorite, a coarse-grained orthopyroxene
containing relatively large amounts of carbonate, with a
crystallization age of 4.5 Gyr. Carbonate globules within
fractures in the rock are dated at 3.6 Gyr. Fractionation of
carbon has taken place to enhance C-13 consistent with
terrestrial biogenic process (but other processes not excluded).
PAHs also appear on interior fracture surfaces in excess of 1
ppm. They present extensive tests and discussion to show that
they are confident that these are all indigenous to the meteorite
and do not represent contamination. Mass spec studies show these
PAHs are complex not simple and suggest (to the authors) a
biogenic source. They then discuss TEM studies of the Fe/S
fraction in the meteorite. Nanometer sized magnetite and Fe-
sulfide phases are associated with Mg-Fe-rich carbonate. These
observed structures and concentrations can be explained by either
inorganic or biogenic processes. However, they argue that the
range of conditions (pH) for inorganic precipitation is unlikely
to have occurred on Mars, whereas biogenic processes seem to
offer a more natural explanation for the detailed structures
observed, and they are apparently similar to terrestrial
magnetofossils (remains of bacterial magnetosomes). SEM studies
of carbonate globules are then discussed (typically ovoid and 100
nm across). Origin of the ovoids and other observed textures is
unclear, but they may be related to terrestrial microfossils, or
they may be erosional features due to partial dissolution of the
carbonate. They do not believe these structures result from
contamination. They suggest possible microbiological activity
for both the ovoid carbonate structures and the Fe-sulfides. On
the basis of a number of circumstantial arguments, they
"interpret that the carbonate globules have a biogenic origin and
were likely formed at low temperatures". (The temperature of
formation of the carbonates in this meteorite has been
controversial).. "It is possible that all of the described
features can be explained by inorganic processes, but these
explanations appear to require restricted conditions." The
evidence consistent with life includes: (1) penetration of the
igneous rock by fluid leading to possible organic deposits of
minerals along veins (2) formation of the carbonate globules much
later than the formation of the rock itself, (3) SEM and TEM
images of the globules that resemble terrestrial biogenic
structures, (4) magnetite and iron sulfide particles that could
have been formed biogenically. The authors feel that the
cumulative effect of these points is to provide "evidence for
primitive life on early Mars"
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MARS METEORITE IMAGES AVAILABLE VIA THE INTERNET
NASA release I96-6
Photographs that support today's briefing at which a team of NASA
and Stanford scientists will discuss their findings showing
strong circumstantial evidence of possible early Martian life,
including microfossil remains found in a Martian meteorite, are
available via the Internet. Real time audio of today's briefing
also will be available from these sites.
The Internet World Wide Web URLs are:
http://www.jsc.nasa.gov/pao/flash
http://cu-ames.arc.nasa.gov/marslife
http://rsd.gsfc.nasa.gov/marslife
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PHOTOGRAPHS OF THE POSSIBLE ANCIENT MARTIAN ORGANISMS
from the Marslife web page: http://cu-ames.arc.nasa.gov/.
[Due to the nature of Marsbugs' format, the photos cannot be
easily e-mailed. However, printable copies of Marsbugs (MS-Word
for Windows format), with the photos included, are available via
anonymous FTP at ftp.uidaho.edu/pub/mmbb/marsbugs.]
A NASA research team of scientists at the Johnson Space Center
and at Stanford University has found evidence that strongly
suggests primitive life may have existed on Mars more than 3.6
billion years ago. The NASA-funded team found the first organic
molecules thought to be of Martian origin; several mineral
features characteristic of biological activity; and possible
microscopic fossils of primitive, bacteria-like organisms inside
of an ancient Martian rock that fell to Earth as a meteorite.
This array of indirect evidence of past life will be reported in
the Aug. 16 issue of the journal Science, presenting the
investigation to the scientific community at large to reach a
future consensus that will either confirm or deny the team's
conclusion.
Below is the photographic evidence for this discovery.
S96-12301 (JPG; TIF) - In the center of this electron microscope
image of a small chip from a meteorite are several tiny
structures that are possible microscopic fossils of primitive,
bacteria-like organisms that may have lived on Mars more than 3.6
billion years ago. A two-year investigation by a NASA research
team found organic molecules, mineral features characteristic of
biological activity and possible microscopic fossils such as
these inside of an ancient Martian rock that fell to Earth as a
meteorite. The largest possible fossils are less than 1/100th the
diameter of a human hair in size while most are ten times
smaller.
S96-12299 (JPG; TIF) - This electron microscope image is a close-
up of the center part of photo number S96-12301. While the exact
nature of these tube-like structures is not known, one
interpretation is that they may be microscopic fossils of
primitive, bacteria-like organisms that may have lived on Mars
more than 3.6 billion years ago. A two-year investigation by a
NASA research team found organic molecules, mineral features
characteristic of biological activity and possible microscopic
fossils such as these inside of an ancient Martian rock that fell
to Earth as a meteorite. The largest possible fossils are less
than 1/100th the diameter of a human hair in size while most are
ten times smaller.
S96-12298 (JPG; TIF) - This electron microscope image shows
extremely tiny tubular structures that are possible microscopic
fossils of bacteria-like organisms that may have lived on Mars
more than 3.6 billion years ago. A two-year investigation by a
NASA research team found organic molecules, mineral features
characteristic of biological activity and possible microscopic
fossils such as these inside of an ancient Martian rock that fell
to Earth as a meteorite. The largest possible fossils are less
than 1/100th the diameter of a human hair in size while most are
ten times smaller. The fossil-like structures were found in
carbonate minerals formed along pre-existing fractures in the
meteorite in a fashion similar to the way fossils occur in
limestone on Earth, although on a microscopic scale.
S96-12297 (JPG; TIF) - This electron microscope image shows egg-
shaped structures, some of which may be possible microscopic
fossils of Martian origin as discussed by NASA research published
in the Aug. 16, 1996, issue of the journal Science. A two-year
investigation found organic molecules, mineral features
characteristic of biological activity and possible microscopic
fossils such as these inside of an ancient Martian rock that fell
to Earth as a meteorite. The largest possible fossils are less
than 1/100th the diameter of a human hair in size while most are
ten times smaller.
S96-12300 (JPG; TIF) - This electron microscope image shows
tubular structures of likely Martian origin. These structures are
very similar in size and shape to extremely tiny microfossils
found in some Earth rocks. This photograph is part of a report by
a NASA research team published in the Aug. 16, 1996, issue of the
journal Science. A two-year investigation by the team found
organic molecules, mineral features characteristic of biological
activity and possible microscopic fossils such as these inside of
an ancient Martian rock that fell to Earth as a meteorite. The
largest possible fossils are less than 1/100th the diameter of a
human hair in size while most are ten times smaller.
S96-12609 (JPG; TIF) & S96-12610 (JPG; TIF) - This
high-resolution scanning electron microscope image shows an
unusual tube-like structural form that is less than 1/100th the
width of a human hair in size found in meteorite ALH84001, a
meteorite believed to be of Martian origin. Although this
structure is not part of the research published in the Aug. 16
issue of the journal Science, it is located in a similar
carbonate glob in the meteorite. This structure will be the
subject of future investigations that could confirm whether or
not it is fossil evidence of primitive life on Mars 3.6 billion
years ago.
S94-032549 (JPG; TIF) - This 4.5 billion-year-old rock, labeled
meteorite ALH84001, is believed to have once been a part of Mars
and to contain fossil evidence that primitive life may have
existed on Mars more than 3.6 billion years ago. The rock is a
portion of a meteorite that was dislodged from Mars by a huge
impact about 16 million years ago and that fell to Earth in
Antarctica 13,000 years ago. The meteorite was found in Allan
Hills ice field, Antarctica, by an annual expedition of the
National Science Foundation's Antarctic Meteorite Program in
1984. It is preserved for study at the Johnson Space Center's
Meteorite Processing Laboratory in Houston.
S95-00690 (JPG; TIF) - This photograph shows orange-colored
carbonate mineral globules found in a meteorite, called ALH84001,
believed to have once been a part of Mars. These carbonate
minerals in the meteorite are believed to have been formed on
Mars more than 3.6 billion years ago. Their structure and
chemistry suggest that they may have been formed with the
assistance of primitive, bacteria-like living organisms. A two-
year investigation by a NASA research team found organic
molecules, mineral features characteristic of biological activity
and possible microscopic fossils inside of carbonate minerals
such as these in the meteorite.
Curator: Annie Platoff
Responsible NASA Official: Kelly Humphries
Page Originator: Johnson Space Center
Page Provider: Ames Research Center
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End Marsbugs Vol. 3, No. 8.
-- Mark ******************************************************** Dr Mark Pallen, Senior Lecturer in Medical Microbiology, St Bartholomew's Hospital Medical College, London, EC1A 7BE currently on a Research Leave Fellowship at Imperial College Rm 502, Dept of Biochem, Imperial College, London, SW7 2AY email:m.pallen@ic.ac.uk WWW: http://www.qmw.ac.uk/~rhbm001/mpallen.html phone: day ++44(0)1715945254, eves ++44(0)1815057937, FAX ++44(0)1715945255 Author, Microbial Underground: http://www.qmw.ac.uk/~rhbm001 ******************************************************** "Presume not mice to scan, the proper study of mankind is man" (not) Alexander Pope ********************************************************