Relic of life in that Martian meteorite? A fresh look

[telfrow]

<i>Since the mid-1990s a great debate has raged over whether organic compounds and tiny globules of carbonate minerals imbedded in the Martian meteorite Allan Hills 84001 were processed by living creatures from the Red Planet. The materials have been under intense scrutiny ever since. <br /><br />Scientists at the Carnegie Institution's Geophysical Laboratory, with colleagues,1 have taken a fresh look at how material associated with carbonate globules was created using sophisticated instrumentation and they compared the results to analogous globules from a volcanic complex on Svalbard, an island north of Norway. It does not appear that living organisms were at work. <br /><br />To some, the tiny carbonate globules from the meteorite seem to resemble minerals that arise from microbial activity on Earth. The team focused on whether macromolecular carbon (MMC) in and around the globules was processed organically or not--an unresolved issue. The team had a complete depth profile of the meteorite. Lead author Andrew Steele explained, "By using micro-Raman spectroscopy and a scanning electron microscope we could detect both the structure of the minerals and the forms of carbon present. We did a similar analysis on carbonate globules from Earth in terrain analogous to Mars--the Bockjord Volcanic Complex on Svalbard--for comparison." </i><br /><br />Full Story Here<br /> <div class="Discussion_UserSignature"> <strong><font color="#3366ff">Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild.</font> - <font color="#3366ff"><em>Tennyson</em></font></strong> </div>

 

[mlorrey]

Which has virtually no scientific content. It implies that you need only magnetite to form the MMC, but fails to dispute the claim that biological processes are needed for magnetite formation, which was the whole point. There are minerals already discovered on Mars which our current understanding requires biological activity to form.<br /><br />Comparing the rock's contents to rocks from Svalbard is also dependent upon the assumption that the Martian meteorite rock was also originally formed in a way similar to that of rock formed on Svalbard. On key fact overlooked, apparently, is that for rock to form as it did on Svalbard requires an oxygen-nitrogen atmosphere and high atmospheric pressure as well as the presence of water, which these debunkers likely claim has never existed on Mars....

 

[yevaud]

<i>...requires an oxygen-nitrogen atmosphere and high atmospheric pressure as well as the presence of water, which these debunkers likely claim has never existed on Mars....</i><br /><br />Actually, I think you'll find that the mainstream are reasonably well convinced that there <i>was</i> once a (reducing) atmosphere, free standing bodies of water, and at least some volcanic activity in Mars' ancient past. Possibly enough and for long enough that perhaps some rather primitive organisms might have existed.<br /><br />Where we usually draw the line, however, is where this potentiality is represented to mean that an intelligent, skilled, technological civilization existed, and left significant artifacts. Mars simply couldn't have had a robust atmosphere for long enough due to a variety of factors to have allowed that to have occurred. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[JonClarke]

Biological processes are most emphatically <b>not</b> required for magnetite formation. It is a common mineral in igenous and metamorphic rocks and very high temperature hydrothermal alternation assemblages.<br /><br />There has been much debate as to whether the specific forms of magetite in ALH84001 indicate biological activity, as they do on earth. Magnetite is secreted by a number of organisms. Proposed examples of possible biogenic magnetite in ALH84001 include: it's ultra-pure and extremely fine-grained magnetite, possible magnetite grain chains, and truncated hexa-octahedra. However none of these are conclusive and while no consensus has been reached, the biological explanation remains unproved.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>at least some volcanic activity<p><hr /></p></p></blockquote><br /><br />Well, that one's pretty much a certainty, judging by the (extinct?) shield volcanoes scattered about on Mars. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[voyagerwsh]

Olivines and pyroxenes tunnels in Nakhla meteorite, an implication to martian biosignatures?<br /><br />Abstract<br /><br />

 

[chew_on_this]

<font color="yellow">Life is rare in our planetary system. It's present only on the earth.</font><br /><br />Pretty bold statement, especially when we've barely even looked for it.<br /><br /><font color="yellow">The environmental requirements for living cells are very, very fastidious. None of these are found any where but on the earth, in our solar system.</font><br /><br />Pure baloney. We're seeing more places than ever that life could possibly thrive.<br /><br /><font color="yellow">If the 'life is rife' crowd would spend as much time and energy tgrying to sustain and promote the biodiversity on this planet as they do searching for the non-existent</font><br /><br />Non-existent? Prove it. Quite the diatribe of drivel.<br />

 

[voyagerwsh]

Don't bother to any astrobiologic aspects or researches. <br />It's non existence. You are paramount on life science, Steve. Give you props!!!<br />

 

[alpha_taur1]

Actually the tunnels themselves (not the minerals) are quite interesting. <br /><br />That's about all we can say, given that the issue of contamination is far more of a concern for Nakhla, Egypt than it is for Allen Hills, Antartica. <br /><br />

 

[voyagerwsh]

One that abiotic process created the tunnels on terrestrial igneous rocks but have not yet discovered, mostly tunnels were borrowed through by microbes. However, lack of DNA detection in Nakhla, and contamination issue have not been addressed by the authors. Nevertheless, tunnels themselves should raise interesting aspects for us.<br /><br />Suggest reading<br /><br />Life in Tiny Tunnels?, <i>Astrobiology Magazin, NASA AMES</i><br />