More results for the possibility of Life on Mars - Page 6

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PostPosted: March 15, 2011 4:05 PM 

Trying to post University of Kansas article


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PostPosted: March 15, 2011 6:56 PM 

Hort; What happened to my KU article?
Thanks, Ben


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Reply: 103

PostPosted: March 15, 2011 9:54 PM 



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PostPosted: March 16, 2011 1:48 PM 

One more time.



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PostPosted: March 16, 2011 2:46 PM 

Ben, sorry it took me so long to free your comments from the comment black hole.

As best as I can figure out the brain dead comment parser doesn't like shtml type links.


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PostPosted: March 16, 2011 3:15 PM 

Wow! I thought it was going to be an earth shattering expose like a modern day micro piltdown man saga. What a letdown.

OK remove those 3.5 billion year "bacterial" cavities from the record of organic matter on Earth. What are the next oldest ones? Are the KU geologists looking into those and seeking to remove them progressively as well.

Anyhow the point is well taken although the connection with the recent paper on putative mars organisms seems to be somewhat tenuous to me. Researchers should indeed be more careful.

BTW, I thought the jury is still out re. the ALH8001?? meteorite and that not all reputable scientists consider that its putative microbial inclusions are not evidence of some sort of life.



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PostPosted: March 16, 2011 4:42 PM 

The researchers did not prove that the forms were not created by bacteria, only that the evidence for bacteria was weakened.

I doubt that there will ever be evidence for ancient life that excludes every conceivable abiotic explanation. One has to weigh the likelihood of the alternatives.

Kevin Author Profile Page

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Reply: 108

PostPosted: March 17, 2011 6:47 AM 

So micro bacteria is "Goo" and as such is unlikely to fossilize, circles and rods can be formed by many different processes, or words to that effect. Does that mean you will never find fossils of bacteria?

This is a bit depressing as no matter what we may eventually find on Mars there will always be strong arguements against it being Life. Fossilized things will not hit the money we will need to find living Bacteria to ever get proof of life. We have seen plenty of things on Martian rocks that look like fossils but there always seems to be a geological reason for these shapes or features.

The further down the road you get the harder it seems to reach the end of it.


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Reply: 109

PostPosted: March 28, 2011 3:14 PM 



"Both isotopes are present in ocean water, but living things on Earth have always shown a preference for incorporating the lighter isotope, carbon 12, into their structures. Thus, where life is abundant, the ratio of carbon 13 to carbon 12 in seawater is higher than it is where there is no life.

Limestone records the composition of the seawater in which it was deposited, including the relative amounts of light and heavy carbon isotopes, so by analyzing the isotope ratio in the rocks, Meyer could infer the abundance of life in the water where the limestone formed."

This suggests a new way to detect microbial life on ancient Mars. In fact, it potentially gives a quantitative estimate of how much life existed when the limestone rock was formed.


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PostPosted: March 28, 2011 4:18 PM 

The Kinetic Isotope Effect imply that the difference in reaction rates of only 4% or so between C12 and C13 chemical reactions - and that hardly seems enough to matter.

But the fact is for some chemical reactions the effect can be to enrich the C12 in the organism by values approaching 0.33%

That's pretty impressive for a purely chemical process.

From the page Why do living organisms exhibit a preference for Carbon-12 over Carbon-13?:

some delta c13 values:

Type of organism delta 13C value

C4 photosynthetic plants -13
C3 photosynthetic plants -28
Thermal vent microorganisms -33

The essential point I want to make is that there is no a priori expectation that all life chemistry favors C12 over C13.

from the paper:

I want to reiterate that most enzymes don't really seem to care which isotope of carbon is present. In fact, even photosynthetic enzymes will fix 13C CO2 molecules when they aren't given a 12C alternative. The reason we see a preference for 12C in biological systems is because some key carbon fixing and metabolic enzymes are "finicky" or "shrewd" enough to prefer the more energetic 12C atoms.

And of course the rock guys will argue that some as of yet unknown inorganic geological process accounts for any enrichment without hard evidence for life - such as some "life-like" reaction in a controlled environment. ( Saay, didn't Viking show something like that? )

Of course, without measurable carbon in the soil the whole point is moot.


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PostPosted: March 28, 2011 4:49 PM 

> without measurable carbon in the soil the whole point is moot.

The idea is that if the microbes preferentially fix C12, and if they are plentiful, then the inorganic carbon, i.e., carbonates, will be depleted in C12. So all we need to look at are the carbonates. We already have found measurable carbonates. I wonder if the APXS readings on Comanche in Gusev included C12/C13 ratios?


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PostPosted: March 28, 2011 6:10 PM 

NIce reference about carbonates on Mars


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PostPosted: March 28, 2011 6:32 PM 

The APXS - can't determine isotope ratios.

Kevin Author Profile Page

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Reply: 114

PostPosted: March 29, 2011 5:42 AM 

Here is the latest from the findings from Lake Mono regarding microbes feeding off Arsenic. There is one big arguement on the go regarding this one, even with all the tools, time and ability to study this here on Earth we cannot agree. Now this is good Science and how Science should work but what hope in hell have we got of proving a finding on Mars when we may only get a short glimpse of it.


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PostPosted: March 29, 2011 11:06 AM 

> The APXS - can't determine isotope ratios.

Oh yeah, I forgot that. Well then, they could measure the isotope rations for the carbonate globule inclusions on the ALH 84001 meteorite, which is believed to have come from Mars.


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PostPosted: May 3, 2011 6:18 AM 

good preparations for a trip to Mawrth Vallis?



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PostPosted: May 3, 2011 12:56 PM 

i believe this would be a better analogy MPJ,

Kevin Author Profile Page

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PostPosted: May 4, 2011 6:58 AM 

What ever future missions to Mars do the scientists must find a way of doing some serious drilling and may have to find away of going miles beneath the surface. It might be worth liaising with oil exploration companies

This might be an interesting read.


Kevin Author Profile Page

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Reply: 119

PostPosted: May 5, 2011 4:14 AM 

Potential area in the MSL ellipse could be very interesting.


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PostPosted: May 6, 2011 4:36 AM 

Kevin, I dont think we will have the opportunity to drill that far below on Mars for a long time ahead. Our best shot would be some compelling evidence of Mars-life which we can gather at or near surface with MSL.
The motivation for large scale astrobiology missions to Mars will only rise to a break even point if MSL will find at least very interesting hints to Mars life if not Mars life itself i guess.

btw. I still not see any ExoMars/Max-C joint mission at the ready around 2016/18 yet without further motivation - nice plans but no action Confused

Here is an interesting read about censorship of ET-life in science and science journals which is realy not good if true:

Extraterrestrial Life and Censorship

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