[X] My Assistant

[ljk4-1]

Wednesday, May 10-12, 2006

Astrobiology Strategy for the Exploration of Mars

National Academy of Science's Keck Building

500 Fifth St., N.W.

Washington, D.C.

Meeting information here:

http://www8.nationalacademies.org/cp/meeti...?meetingid=1352

If you would like to attend the sessions of this meeting that are open
to the public or need more information, please contact:

Contact Name: Rod Howard
Email: rhoward@nas.edu
Phone: 202-334-3477
Fax: 202-334-3701

[ngunn]

Do we know if this will include consideration of Cairns-Smith's clay theory? I am trying to find out how we might recognise evolved clays if they are (or once were) present on Mars. Can anybody here shed light?

[Guest_Richard Trigaux_*]

A good thing!

The last hopes to find life on Mars rely on tenuous indices on very special places. And even if we were on these places, we could find nothing without appropriate instruments. So the places must be identified, together with how to detect present or past life.

A secondary question still holds even if martian life is completely absent. So long as there are some doubts, drastic cautions must be taken against a contamination of earth by martian bacteria. But even if there are no such bacteria, we still need not to contaminate mars. There are several reasons for this. For instance Earth archeobacteria could easily colonize deep aquifers on mars, and completelly change their chemistry, destroying a priceless virgin environment. Eventually this could result even in geological changes.

So to meet these difficult chalenge, there will be not too much strategy.

[ngunn]

Absolutely right. The question is do we limit what we mean by life (and contamination) to carbon based organisms? As others have long ago pointed out if in fact carbon based biochemistry never took hold on Mars that would make it the ideal place to test the clay theory.

IF the clay theory proves sound and IF indeed clays did start to evolve on Mars in the absence of the more high-tech carbon biochemistry then that raises numerous questions. The fossil remains of these evolved clays could be quite extensive across the planet, but would we recognise them? Are we even looking? What sorts of instruments should be used for the search? Have we already found them without realising what they are? How vulnerable might they be to contamination?

I hope very much that someone is onto all this, but I'm not sure if clay minerals specialists participate in Astrobiology conferences, or whether the equation BIO=CARBON holds. Issues on the fault line between academic disciplines can for this reason alone be all too easily treated as peripheral, even off-beat, in both communities.

[ljk4-1]

Have any real scientists made some serious studies of those
unusual formations found by the MERs, such as the Rotini?

http://www.newsweek-interactive.org/id/6969396/

[Guest_Richard Trigaux_*]

Absolutely right. The question is do we limit what we mean by life (and contamination) to carbon based organisms? As others have long ago pointed out if in fact carbon based biochemistry never took hold on Mars that would make it the ideal place to test the clay theory.

IF the clay theory proves sound and IF indeed clays did start to evolve on Mars in the absence of the more high-tech carbon biochemistry then that raises numerous questions. The fossil remains of these evolved clays could be quite extensive across the planet, but would we recognise them? Are we even looking? What sorts of instruments should be used for the search? Have we already found them without realising what they are? How vulnerable might they be to contamination?

I hope very much that someone is onto all this, but I'm not sure if clay minerals specialists participate in Astrobiology conferences, or whether the equation BIO=CARBON holds. Issues on the fault line between academic disciplines can for this reason alone be all too easily treated as peripheral, even off-beat, in both communities.

Eventually, we could find, not life, but one of its primary steps. It is well known that clay play a role of catalists, favourising certain amino acids and certain nucleic bases among tens of similar bodies. As we could expect, our life is precisely made of those amino acids and nucleic bases, strongly hinting to the role of clays into early pro-life chemistry.

We could eventually find on mars one of these steps, for instance clays having concentrated the right amino-acids, but which not evolved into actual living being, or even some more advanced step. Even if life itself is not present, it would be a great discovery to find one of its primary stades.

As to non-carbon life, it is a bit speculative, but we cannot dismiss it for simply this reason. By definition we don't know its chemistry. So its existence could be detected only through the discovery of living beings, or their effect onto the environment. This should be anyway included in any search strategy.

Eventually we could find in clay some exotic things, such as a self-catalytic mixture which evolved through a selection, but never gave cells. If such a thing ever existed on earth, it would of course have disappeared for long. But finding such a thing would give us clues on early prebiotic stages, or on other evolution paths than just cells or carbon-based life.

By the way I have some doubt about finding 4 billion years old amino acids. Perhaps we should search for degraded products. Oil shales?

[ngunn]

The clay theory postulates that clay minerals started to evolve on their own, independently of carbon chemistry. This is the only form of non-carbon life I was referring to. You can call it 'not life but a precursor' if you prefer a definition of life that implies carbon chemistry - it's a matter of word usage. The point is that clays alone might have been capable of evolutionary adaptation through selection during many cycles of wetting, drying and transportation.

As you mention, clays are good at catalysing carbon-chemical reactions, such as the formation of amino acids. Originally this would have been advantageous to the clays (membrane formation etc.), but eventually (so the theory goes) these 'helpers' hijacked their hosts and what's left on Earth are the clay-less carbon-chemistry organisms we see today. These in turn have erased all trace of their mineral precursors. The question is: did this process start on Mars, and if so how far did it get?

For a one-click way into the references for clay theory try:
http://originoflife.net/crystals/index.html

[RNeuhaus]

The astrobiology strategy is to find any places which is only dated as Noachian epoch? This epoch, up to 3.9 Ma is too old too keep any biological traces? The strategy does not include to other places which is of Hesperian age (3.8 to 3.4 Ma)? The problem of Hesperian is of the acidity land and liquid that degrades faster the biological stuffs.

Both are the problems : Noachian - Long age, Hesperian - Acidity.

Then, how about finding any astrobiology particles of any Amazon age places? What are these problems (these places are of rich iron oxide - Hematies). Does this harm as much as the acidity places?

Rodolfo

[ljk4-1]

Small molecule interactions were central to the origin of life

http://www.spaceref.com/news/viewpr.nl.html?pid=19856

"In an important new paper forthcoming in the June issue of The Quarterly Review
of Biology, Robert Shapiro (New York University) argues against the widely held
theory that the origin of life began with the spontaneous appearance of a large,
replicating molecule such as RNA."

[Guest_BruceMoomaw_*]

Noachian clays still strike me as by far the best possible site for any fossil search -- both as an environment where life might have evolved, and as a medium that's good at preserving fossils (both microscopic and biochemical). Every other possible type of Martian site is a very poor second, and even if MSL investigates such a site and comes up empty in a search for organics I would be inclined to think that its followup should be sent to another clay site. Mars Express' results in this regard are of enormous importance.

[Bob Shaw]

Noachian clays still strike me as by far the best possible site for any fossil search...

Bruce:

Yes - and preferably in locations where erosion has acted to provide a natural 'sorting' of materials, or where 'cuts' are to be found in the landscape. Exhumed bends in ancient river beds, or cliffs along 'recent' outflow channels would be good places to look. Both require rather sophisticated rovers, though - perhaps even (dare I say it) two-legged ones!

Bob Shaw