Researchers from JSC and Stanford have found evidence that strongly suggests primitive life may have existed on Mars more than 3.6 billion years ago. The evidence has been found inside meteorites recovered from the Antarctic icecap. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller.
Evidence of several kinds has been announced:
If the evidence survives peer review over the next months and years, this will be a very strong impetus for a Mars mission, possibly of the sort described by Dr. Robert Zubrin in varous publications. The search for fossil traces of life will certainly become a major item on the agenda for upcoming robotic Mars rover missions.
NASA has released a number of electron microscope images of the meteorites. These images show both the purported microfossils and biogenerated mineral deposits.
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.
Here is a close-up of the center of S96-12301. Tube-like structures might
be archaeobacteria-like microfossils.
S96-12298 (jpeg). This electron microscope image shows extremely tiny tubular structures. 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.
Note the egg-shaped structures in this electron microscope image.
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.
S96-12609 (jpeg) and S96-12610 (jpeg). 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, This structure is not part of the Aug. 16, 1996 Science paper but is located in a similar carbonate glob in the meteorite. It will be the subject of future investigations.
S94-032549 (jpeg). 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.
This photograph shows orange-colored carbonate mineral globules found in ALH84001. The structure and chemistry suggest that they may have been formed with the assistance of primitive, bacteria-like living organisms.
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