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#1 2008-03-24 03:22:42

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: New Clues to Guide Search for Life on Mars

Chlorides_ODY_fig1a_br.jpg

New Clues to Guide Search for Life on Mars - 20 Mar 2008

PASADENA, Calif. - NASA's Mars Odyssey orbiter has found evidence of salt deposits. These deposits point to places where water once was abundant and where evidence might exist of possible Martian life from the Red Planet's past.

A team led by Mikki Osterloo of the University of Hawaii, Honolulu, found approximately 200 places on southern Mars that show spectral characteristics consistent with chloride minerals. Chloride is part of many types of salt, such as sodium chloride or table salt. The sites range from about a square kilometer (0.4 square mile) to 25 times that size.

"They could come from groundwater reaching the surface in low spots," Osterloo said. "The water would evaporate and leave mineral deposits, which build up over years. The sites are disconnected, so they are unlikely to be the remnants of a global ocean."

Scientists used Odyssey's Thermal Emission Imaging System, a camera designed and operated by Arizona State University, Tempe, to take images in a range of visible light and infrared wavelengths. Thermal infrared wavelengths are useful for identifying different mineral and rock types on the Martian surface. Osterloo found the sites by looking through thousands of images processed to reveal, in false colors, compositional differences on the Martian surface.

Plotted on a Mars map, the chloride sites appear only in the southern highlands, the most ancient rocks on Mars. Osterloo and seven co-authors report the findings in this week's issue of the journal Science.

"Many of the deposits lie in basins with channels leading into them," said Philip Christensen, co-author and principal investigator for the camera at Arizona State University. "This is the kind of feature, like salt-pan deposits on Earth, that's consistent with water flowing in over a long time."

Scientists think the salt deposits formed approximately 3.5 to 3.9 billion years ago. Several lines of evidence suggest Mars then had intermittent periods with substantially wetter and warmer conditions than today's dry, frigid climate.

Scientists looking for evidence of past life on Mars have focused mainly on a handful of places that show evidence of clay or sulfate minerals. Clays indicate weathering by water, and sulfates may have formed by water evaporation. The new research, however, suggests an alternative mineral target to explore for biological remains.

"By their nature, salt deposits point to a lot of water, which potentially could remain standing in pools as it evaporates," said Christensen. "That's crucial. For life, it's all about a habitat that endures for some time."


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#2 2012-05-05 20:01:59

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 10,637

Re: New Clues to Guide Search for Life on Mars

There's another article at THIS SITE which adds to the evidence that life exists on Mars - at least under the surface.

Apparently there are thriving colonies of bacteria and archaea (primitive microorganisms) about 2 metres below the Atacama Desert in Chile, the driest desert on our planet.

oo40827_web.jpg

The microbes cling to hygroscopic minerals, such as salts, which attract water out of the air.

"We have named it a 'microbial oasis' because we found microorganisms developing in a habitat that was rich in halite (rock salt) and other highly hygroscopic compounds (anhydrite and perchlorate) that absorb water" explained Victor Parro, researcher from the Center of Astrobiology (INTA-CSIC, Spain) and coordinator of the study.

Furthermore, the substrates where the microbes live favour deliquescence, which means they can attract the limited moisture in the air, condensing it on the surface of the salt crystals. Thin films of water that are a few microns thick are thereby formed.

The species are not very different from others in similar hypersaline environments, but the peculiar thing is that they were discovered at a depth of between 2 and 3 metres, without any oxygen or sunlight.

No oxygen, no sunlight, almost no water - but still the colonies thrive. smile

Of course, the other advantage of the thin films of water forming on the surface of these minerals is that they are highly saline, which means the freezing point of the water is lowered way down below zero - very handy on a cold planet like Mars. smile

The researcher explained that saline deposits have been found on the red planet, therefore it is possible to think that there maybe hypersaline environments in its subsoil. "The high concentration of salt has a double effect: it absorbs water between the crystals and lowers the freezing point, so that they can have thin films of water (in brine) at temperatures several degrees below zero, up to minus 20°C."

This estimate of the extent of the lowering of the freezing point of water is probably very conservative. As we saw a while back over at the Northern Lowlands thread, Antarctic brine pools like Don Juan Pond can stay liquid down to -24°C.

DJP.view.JPeG
[SIZE=1]Don Juan Pond, Antarctica. Posted at 'Northern Lowlands' Mar 21st 2009[/SIZE]

But getting further below -20°C would require a mixture of salts rather than just good ol' sodium chloride. So we need more information about the varieties of salt 2 metres under the Martian surface before we can talk about water remaining liquid there.
[But then I suppose by the time we're able to dig up soil from such a depth on Mars, we'll be able to examine it for microbes directly anyhow. roll ]

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#3 2012-05-06 16:02:38

Void
Member
Registered: 2011-12-29
Posts: 1,806

Re: New Clues to Guide Search for Life on Mars

I hate to be a posting pig, but that picture just had to draw me in.

I see the rocks in the pool of water.

Even though that pool of water may be very cold (And I presume any adapted life in it have an extremely low metabolism, I have to wonder what the temperature excursions are for the soil at the bottom of the pond.  It seems to me that the warmth of the noonday sunlight must improve it't temperature.

I also see the rocks poking up out of the brine.  That in fact really draws me.  Brine ponds have not been photographed on Mars, but I am not sure they cannot exist.  At least perhaps they can exist at some point in the procession of the tilting of the poles, if for instance snowfall were to contact a salt flat. smile (Your postings indicate exposed salt flats, and the ice that is quite low in lattitude under the soil in places suggests snowfall has occurred at some time in the past 100,000 years)?

Anyway a rock soaking in brine, if it is at least a bit porous, in the conditions where day night temperatures are extreem, suggests that that process could make the rocks habitible.  Where your articles suggest an extrordinary tollerance for salt by some organisms, it does leave in question if the temperatures on Mars can be high enough.  I would think that at noon time during the summer of the southern hemmisphere, 1/8-1/4 inches inside of the rock, yes.  And the rocks might be soaking in brine.  Perhaps not an open pool of water, but a pool of brine under the surface of the soil.

So, I suppose that if the rocks were like wicks, they woud draw moisture upwards to the exposed surface of the rock.  Sandstone perhaps? 

It is a feature of the Arctic ocean that ice on the ice pack can become fresh enough to drink even though it started as salt water ice.  Freezing causes brine to leave the ice through brine channels. 

So, I speculate that there might be a hope that rocks wicking up mosisture out of briny mud on Mars (Presumed covered with a dry crust), might also from exposure to the cycling of temperatures on Mars generate a less briny fluid for microbes to use within the rock.  It is even possible that orgainsms in the rocks, just under the surface might use photosynthisis.  I would only expect this if they were a remnant organism from Mars past, or some organism that somehow made it to Mars from Earth or Ancient Venus.

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#4 2012-05-07 12:20:54

louis
Member
From: UK
Registered: 2008-03-24
Posts: 2,675

Re: New Clues to Guide Search for Life on Mars

Void wrote:

I hate to be a posting pig, but that picture just had to draw me in.

I see the rocks in the pool of water.

Even though that pool of water may be very cold (And I presume any adapted life in it have an extremely low metabolism, I have to wonder what the temperature excursions are for the soil at the bottom of the pond.  It seems to me that the warmth of the noonday sunlight must improve it't temperature.

I also see the rocks poking up out of the brine.  That in fact really draws me.  Brine ponds have not been photographed on Mars, but I am not sure they cannot exist.  At least perhaps they can exist at some point in the procession of the tilting of the poles, if for instance snowfall were to contact a salt flat. smile (Your postings indicate exposed salt flats, and the ice that is quite low in lattitude under the soil in places suggests snowfall has occurred at some time in the past 100,000 years)?

Anyway a rock soaking in brine, if it is at least a bit porous, in the conditions where day night temperatures are extreem, suggests that that process could make the rocks habitible.  Where your articles suggest an extrordinary tollerance for salt by some organisms, it does leave in question if the temperatures on Mars can be high enough.  I would think that at noon time during the summer of the southern hemmisphere, 1/8-1/4 inches inside of the rock, yes.  And the rocks might be soaking in brine.  Perhaps not an open pool of water, but a pool of brine under the surface of the soil.

So, I suppose that if the rocks were like wicks, they woud draw moisture upwards to the exposed surface of the rock.  Sandstone perhaps? 

It is a feature of the Arctic ocean that ice on the ice pack can become fresh enough to drink even though it started as salt water ice.  Freezing causes brine to leave the ice through brine channels. 

So, I speculate that there might be a hope that rocks wicking up mosisture out of briny mud on Mars (Presumed covered with a dry crust), might also from exposure to the cycling of temperatures on Mars generate a less briny fluid for microbes to use within the rock.  It is even possible that orgainsms in the rocks, just under the surface might use photosynthisis.  I would only expect this if they were a remnant organism from Mars past, or some organism that somehow made it to Mars from Earth or Ancient Venus.

All that sounds feasible.  During summer on Mars temperatures are often above freezing. Organisms on Earth sometimes have only very brief windows of active experience followed by long periods of hibernation.  Maybe the organisms on Mars would spend 20 months out of 24  inactive and become active only during those brief summer months.


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#5 2017-08-28 17:07:13

EnlaleHap
Member
From: USA
Registered: 2017-08-10
Posts: 5

Re: New Clues to Guide Search for Life on Mars

Has the probability of Mars once harboring life just increased? It appears that this may be the case.

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#6 2017-10-05 04:37:13

louis
Member
From: UK
Registered: 2008-03-24
Posts: 2,675

Re: New Clues to Guide Search for Life on Mars

Here's an interesting collection of anomalies with discussion of possible explanations.  NASA seem unwilling to engage on those they don't have a ready explanation for.

https://www.thoughtco.com/the-most-myst … rs-4123208

And here's a discussion of ventifacts:

https://planetarygeomorphology.wordpres … -and-mars/

Last edited by louis (2017-10-05 04:39:53)


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#7 2017-10-05 18:05:08

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 10,637

Re: New Clues to Guide Search for Life on Mars

Since there is still methan gas being released from mars and the probable water it would make sense that as the water retreated that the methane would cause warming of the planet until the atmospher would be blown away once more causing it to force another releasal of methane as the water continued to sublime away from mars due to the triple point continuing to moce for what would keep it at liquid water.

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