Life on Mars part two

Mark Pallen m.pallen at ic.ac.uk
Mon Aug 12 06:15:04 EST 1996


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 at micro.microbio.uab.edu>
Subject: Marsbugs. V.3. N.8. Part 2.
To: "Dr. Julian and Melissa Hiscox" <marsgene at 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" 
----------------------------------------------------------------- 
 
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 
----------------------------------------------------------------- 
 
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 at 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
********************************************************



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