AlexBlackwell
Jan 29 2007, 09:45 PM
Dig deeply to seek life on MarsAGU Release No. 07-03
29 January 2007
This refers to the following paper, which was published online today in
Geophysical Research Letters:
Dartnell, L. R.; Desorgher, L.; Ward, J. M.; Coates, A. J.Modelling the surface and subsurface Martian radiation environment: Implications for astrobiologyGeophys. Res. Lett., Vol. 34, No. 2, L02207
10.1029/2006GL027494
30 January 2007
Abstract
nprev
Jan 29 2007, 11:43 PM
Interesting. Wonder if degradation of near-surface organic compounds over time is also addressed by this paper. If there is in fact anything there (even down deep), you'd think that there would be detectable organic residue within our reach due to various regolith mixing processes (esp. in the polar areas), unless the radiation environment is just too severe for them to survive...
ElkGroveDan
Jan 30 2007, 12:13 AM
AlexBlackwell
Jan 30 2007, 12:24 AM
QUOTE (nprev @ Jan 29 2007, 01:43 PM)
Interesting. Wonder if degradation of near-surface organic compounds over time is also addressed by this paper.
After a quick skim, all I could see relating to organics was the brief excerpt from paragraph 3:
QUOTE
Solar UV rapidly deactivates unshielded cells [Cockell and Raven, 2004], and is also believed to have created highly oxidising surface conditions that destroy organic molecules in the topsoil. The Viking lander probes found no trace of organic compounds, not even at the level expected from meteoritic infall [Yen et al., 2000]. UV penetrates only millimetres into regolith [Cockell and Raven, 2004], but there is estimated to be around a meter's depth of loose topsoil [Soderblom et al., 2004] within a portion of which wind-mixing of oxidants is expected to present a serious biological hazard. Beyond the penetration depth of UV the ionising radiation of solar energetic protons (SEP) and galactic cosmic rays (GCR) dominate.
That the paper doesn't address organics in greater depth shouldn't be too surprising since its thrust is with the radiation environment, not the widely suspected near-surface oxidants.
nprev
Jan 30 2007, 12:41 AM
True; always interesting to see a new set of contraints introduced to the problem, though. Thanks, Alex!
Looks like it's time to think about deep (>7m) core drilling experiments at least in order to differentiate between near-surface environmental effects & bulk regolith composition. This seems worth doing even if organics aren't the focus given the possible effects of hyper-oxidants on the terrain over time (esp. during transient moist conditions, if any).
Zvezdichko
Jan 30 2007, 03:56 PM
That's why I raised the question about the penetrators. They can "dig themselves" at least two meters under the martian soil, then a drill may go even deeper. I'd like to see yet another Deep Space 2 mission.
ustrax
Feb 5 2007, 03:57 PM
Monday bonus interview at
spacEurope...
"If cells were only recently brought to the surface, such as in the gullies in crater walls that we’ve seen flow with liquid water in the last few years, then they could survive the radiation for long enough for us to sample them."
nprev
Feb 6 2007, 02:40 AM
Food for thought indeed...
I wonder if MRO is capable of further refining our understanding of the frequency of these events (if that's what's really happening). What would be most desirable would be to find some sort of cyclic process area--ideally a periodic "eruptor" or two--that we could predict far enough in advance for a sort of a mini-MSL launch.
ustrax
Mar 16 2007, 07:39 PM
Follow the water?...
Follow the oil! ""Search for oil reservoirs on Mars" was the result of a deep study on the history of Mars, focused on the search for oil on the Red Planet, having into account that oil might be a reserve of organic material for potential life forms."
tty
Mar 16 2007, 08:24 PM
I know we have at least one petroleum geologist on the forum, so perhaps it is unwise of me to sound off on the subject. However the whole premise sounds weird to me. Here on Earth oil is created from fossils (mostly marine, occasionally freshwater), so to find oil on Mars seems to me require that life and liquid water has existed there in the past, and on a fairly large scale too.
Oil creation also requires a fair amount (but not to much) heat, so I suppose the right place to search would be on the outskirts of the Tharsis bulge.
For oil to survive for any length of time also requires an impermeable caprock. I suppose ice would do quite well under martian conditions.
nprev
Mar 17 2007, 12:45 AM
Mmm...I don't know if all possible hypotheses for petroleum formation have been completely ruled out yet, TTY. Last I heard on the subject there was still no firm consensus that oil is indeed a true fossil fuel...
MarsIsImportant
Mar 17 2007, 01:52 AM
QUOTE (nprev @ Mar 16 2007, 07:45 PM)
Mmm...I don't know if all possible hypotheses for petroleum formation have been completely ruled out yet, TTY. Last I heard on the subject there was still no firm consensus that oil is indeed a true fossil fuel...
That's true. Rumors have it that there are alternate origins for 'supposed' fossil fuels. It's hard to prove one way or the other. That's why a return sample from Titan is so important!
edstrick
Mar 17 2007, 08:28 AM
The scientific consensus is as stong as in the "Evolution vs Intelligent Design" debate that petroleum <but not all hydrocarbons.. there are methane seeps from the mantle, apparently> is from biologic materials.
Tommy Gold, the chief proponant of the primordial mantle origin theory, was a fine physicist, but no geochemist or organic chemist and was always able to ignore evidence from outside his areas of interest, while cherry-picking evidence that supported his theories. When he was right, he was very very right, but he was often wildly and "crankishly" wrong.
nprev
Mar 17 2007, 05:50 PM
Gotcha, Ed; thanks for the clarification. Given all that, though, any Martian hydrocarbons found still wouldn't constitute definitive proof of past life in my opinion, unless perhaps there were well-evolved bugs thriving in the mix. Petroleum is an extremely complex substance, so I doubt that Mars "oil" would be a close chemical match in many important respects.
Still, who really knows? Let's go drillin' & find out!
Mizar
Mar 17 2007, 09:59 PM
ustrax
Mar 19 2007, 04:39 PM
QUOTE (Mizar @ Mar 17 2007, 09:59 PM)
I say:
Follow the abyss !
Dear Mizar, the party is taking place
here...
Mizar
Mar 19 2007, 10:36 PM
ustrax, thanks, I noticed that later today.
ustrax
Apr 3 2007, 02:10 PM
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