[meteorite-list] Life on Mars? (Again) Tissint

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Thu, 4 Dec 2014 17:16:32 -0500
Message-ID: <CAKBPJW8TCYsiqPsQPruJS5CV+r773mXyEVUKkDLYj-Yan77jdA_at_mail.gmail.com>

Hi David,

It's good to hear from you. :)

So, the fresh, relatively-uncontaminated nature of Tissint was what
allowed the organic determination to be made with more certainty? In
other words, the presence of these "organic carbon traces" could only
come from terrestrial contamination or biologic action on Mars in the
distant past, and previous analysis on other Martian meteorites had
yielded similar data, but the results could be due to terrestrial
contamination that was obviously not present in Tissint?

Best regards,

MikeG

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On 12/4/14, David R. Vann via Meteorite-list
<meteorite-list at meteoritecentral.com> wrote:
> Thought this might be of interest:
> This is from "Laboratory Equipment", but it is making the rounds of such
> rags. Let's see if I beat Paul H. on this one. ;)
> If you are interested in the original article, and do not have access,
> please contact me off-list.
>
> Did Mars ever have life? Does it still? A meteorite from Mars has reignited
> the old debate. An international team that includes scientists from EPFL
> has
> published a paper in the scientific journal Meteoritics and Planetary
> Sciences, showing that Martian life is more probable than previously
> thought.
> "So far, there is no other theory that we find more compelling," says
> Philippe Gillet, director of EPFL's Earth and Planetary Sciences
> Laboratory.
> He and his colleagues from China, Japan and Germany performed a detailed
> analysis of organic carbon traces from a Martian meteorite, and have
> concluded that they have a very probable biological origin. The scientists
> argue that carbon could have been deposited into the fissures of the rock
> when it was still on Mars by the infiltration of fluid that was rich in
> organic matter.
> Ejected from Mars after an asteroid crashed on its surface, the meteorite,
> named Tissint, fell on the Moroccan desert on July 18, 2011, in view of
> several eyewitnesses. Upon examination, the alien rock was found to have
> small fissures that were filled with carbon-containing matter. Several
> research teams have already shown that this component is organic in nature.
> But they are still debating where the carbon came from.
> Maybe biological, but not from our planet
> Chemical, microscopic and isotope analysis of the carbon material led the
> researchers to several possible explanations of its origin. They
> established
> characteristics that unequivocally excluded a terrestrial origin, and
> showed
> that the carbon content were deposited in the Tissint's fissures before it
> left Mars.
> The researchers challenged previously described views (Steele et al.,
> Science, 2012) proposing that the carbon traces originated through the
> high-temperature crystallization of magma. According to the new study, a
> more likely explanation is that liquids containing organic compounds of
> biological origin infiltrated Tissint's "mother" rock at low temperatures,
> near the Martian surface.
> These conclusions are supported by several intrinsic properties of the
> meteorite's carbon, e.g. its ratio of carbon-13 to carbon-12. This was
> found
> to be significantly lower than the ratio of carbon-13 in the CO2 of Mars's
> atmosphere, previously measured by the Phoenix and Curiosity rovers.
> Moreover, the difference between these ratios corresponds perfectly with
> what is observed on Earth between a piece of coal - which is biological in
> origin - and the carbon in the atmosphere. The researchers note that this
> organic matter could also have been brought to Mars when very primitive
> meteorites - carbonated chondrites - fell on it. However, they consider
> this
> scenario unlikely because such meteorites contain very low concentrations
> of
> organic matter.
> "Insisting on certainty is unwise, particularly on such a sensitive topic,"
> warns Gillet. "I'm completely open to the possibility that other studies
> might contradict our findings. However, our conclusions are such that they
> will rekindle the debate as to the possible existence of biological
> activity
> on Mars - at least in the past."
>
> David R. Vann, Ph.D.
> Department of Earth and Environmental Science
> The University of Pennsylvania
> 240 S. 33rd St.
> Philadelphia, PA 19104
>
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Received on Thu 04 Dec 2014 05:16:32 PM PST