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Organic Chemicals on Mars

#1
Yazata Offline
NASA just held a press conference and has announced two interesting bits of new information from its Curiosity rover.

News story from the American Chemical Society here:

https://cen.acs.org/physicalChemistry/as...ars/96/i24

First, they have found organic chemicals in sedimentary rock a location that was once a liquid water lake, long long ago (3.5 billion years ago). The chemicals seem to be small fragments of what once were bigger macromolecules. But it isn't entirely clear that the macromolecules were ever associated with life.

Assuming Mars and Earth formed at the same time, Mars would have been about 1 billion years old when this lake existed. Life on Earth may (speculatively) have been a few hundred million years old at that time, probably very simple prokaryotic cells like bacteria and archaea.

The molecules found were (in the words of the ACS story) "thiophene, methylthiophenes, and methanethiol, which are probably fragments from larger organic macromolecules in the sediment. These organic deposits may be something like kerogen, the fossilized organic matter found in sedimentary rocks on Earth that contain a jumble of waxy hydrocarbons and polycyclic aromatic hydrocarbons."

I wonder whether the "probably" and the "may" in the source of these thiols being kerogen is more than mere speculation. On Earth kerogen is an early stage in the evolution of petroleum, and it typically has a living origin. But in this Mars case we still can't be certain that these small organic molecules observed really are fragments of kerogen, or that the kerogen indeed had a living origin.

https://en.wikipedia.org/wiki/Kerogen

The full-text of the paper published by Science (which I haven't read yet) is here:

http://science.sciencemag.org/content/36.../1096.full

The other news concerns methane outgassing. Methane has been noted in low concentrations previously, but seemingly at random times. Now Curiosity has determined that it's always there, but the concentrations vary seasonally. Curiosity also detected occasional spikes in the concentrations. What makes this interesting is that one of the possible sources of the methane might be microbial action. (It is on Earth.) But the source on Mars might have nothing to do with life.
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#2
C C Offline
I'll take the pessimistic view about it for the time being. There's always some buzz popping-up intermittently over the years. A minority of scientists still cling to the idea that the Viking missions even found signs of life over 40 years ago.

~
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#3
Yazata Offline
(Jun 7, 2018 08:17 PM)Yazata Wrote: The other news concerns methane outgassing. Methane has been noted in low concentrations previously, but seemingly at random times. Now Curiosity has determined that it's always there, but the concentrations vary seasonally. Curiosity also detected occasional spikes in the concentrations. What makes this interesting is that one of the possible sources of the methane might be microbial action. (It is on Earth.) But the source on Mars might have nothing to do with life.

Here's the paper for that one

http://science.sciencemag.org/content/36.../1093.full
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