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Blob
2006-Jun-30, 11:08 AM
A mysterious shiny coating found on rocks in many of Earth's arid environments could reveal whether there was once life on Mars, according to new research.

The research, published in the July edition of the journal Geology, reveals that the dark coating known as desert varnish creates a record of life around it, by binding traces of DNA, amino acids and other organic compounds to desert rocks. Samples of Martian desert varnish could therefore show whether there has been life on Mars at any stage over the last 4.5 billion years.
The researchers hope that these results will encourage any future Mars Sample Return mission to add desert varnish to its Martian shopping list.

"If silica exists in varnish-like coatings in Martian deserts or caves, then it may entomb ancient microbes or chemical signatures of previous life there, too. Desert varnish forms over tens of thousands of years and the deepest, oldest layers in the varnish may have formed in very different conditions to the shallowest, youngest layer. These lustrous chroniclers of the local surroundings can provide a window back in time. Martian desert varnish would contain a fascinating chronology of the Martian setting" - Dr Randall Perry.

Read more (http://www.imperial.ac.uk/P7911.htm)

See also (http://www.gsajournals.org/gsaonline/?request=get-document&doi=10.1130%2FG22352A.1)
Title: `Baking black opal in the desert sun: The importance of silica in desert varnish`
Authors: Perry, Randall S., Lynne, Bridget Y., Sephton, Mark A., Kolb, Vera M., Perry, Carole C., Staley, James T.
Journal: Geology (subscription)

Extra information:
What is desert varnish? (http://minerals.caltech.edu/FILES/VARNISH/Index.htm)
Desert varnish is a dark coating on rocks found in arid regions. The coating is composed dominantly of fine-grained clay minerals. Within the clays are black manganese oxide and red iron oxide. A more general term is rock varnish which applies to dark coatings on rocks in general.

Ronald Brak
2006-Jun-30, 11:39 AM
Personally I was hoping the current rovers would simply discover a layer of limestone in a crater wall. No such luck so far.

Blob
2006-Jun-30, 03:08 PM
Hum,
i was hoping the rovers would spot some Martian rock art (http://www.bautforum.com/showthread.php?t=42331)

publiusr
2006-Jun-30, 04:50 PM
The researchers hope that these results will encourage any future Mars Sample Return mission to add desert varnish to its Martian shopping list.

Varnish? Ah...I see...so Bob Vila made the Face on Mars.

This Old Mars--

"As you can see, Bob, the homeowners have been negectful in their weatherstripping--they've got dust all over. But they put down some good varnish."

"That's right Norm...stumble...who keeps leaving these toy rovers all over the place?'

"I guess we will have to add handrails, Bob."

Blob
2006-Jun-30, 06:55 PM
Hum,
to create their petroglyphs, Martians would scraped of the varnish to reveal the white stone underneath...

http://msnbcmedia.msn.com/j/msnbc/Components/Photos/060630/060630_rock_hmed_12p.thumb.jpg

darkhunter
2006-Jul-02, 04:40 PM
Hum,
to create their petroglyphs, Martians would scraped of the varnish to reveal the white stone underneath...

http://msnbcmedia.msn.com/j/msnbc/Components/Photos/060630/060630_rock_hmed_12p.thumb.jpgSo we need to find the Martian equivilent to a hill giant or the White Horse...(you can do a Google search on hill giant UK to find pictures--they are described as "rude" on some websites)


Would the varnish alone be enough to show there was life there or would the probe have to do tests? Do the probes have the gear to do the required tests if the find any?

Blob
2006-Jul-02, 05:19 PM
Hum,
No need, as i`m a pagan, and know all about these things, (plus i have google earth) ;) .

Māori
2006-Jul-02, 05:26 PM
Okay, this is funny from "extra information".

Things which look like varnish but which are not
Counterfeit manganese deposits can take various forms. This is an algal stream deposit (46K) from Rock Creek, California. It looks like a coating of manganese oxide, but contains no manganese at all.

Other than that, very nice links, Blob! :clap:

01101001
2006-Jul-02, 06:46 PM
Would the varnish alone be enough to show there was life there or would the probe have to do tests? Do the probes have the gear to do the required tests if the find any?
NASA Astrobiology Magazine: The Martian Hot Spots (http://www.astrobio.net/news/article1604.html)


Q: Have you seen anything like desert varnish?

A: [Joy Crisp:] We did on one rock, clearly, near the rim of Bonneville crater. There, as we ground into the rock, we could see that we were removing an outer coating. We took measurements, and could see some indications of the chemistry of that coating. We don't know if that rock at some point was exposed to some surface water, or if it was buried in the soil where there was a little bit of water, forming this coating. But it had water signatures.
The rovers don't have the tools to confirm biogenic desert varnishes.

01101001
2008-Dec-17, 09:22 PM
Revived for news. After a 2-1/2-year sleep.

Planetary Science Institute press release archive: Rock Varnish: A Promising Habitat for Martian Bacteria (http://www.psi.edu/press/):


Rock Varnish: A Promising Habitat for Martian Bacteria

As scientists search for life on Mars, they should take a close look at rock varnish, according to a paper in the current issue of the Journal of Geophysical Research.

The paper describes how a research team led by Kimberly R. Kuhlman, of the Tucson-based Planetary Science Institute, found bacteria associated with rock varnish in an area where the surrounding soils were essentially devoid of life. The study suggests that rock varnish could provide a niche habitat for microbial life on Mars and in other extraterrestrial environments devoid of liquid water.

Rock varnish is an extremely slow-growing coating that forms on the surfaces of rocks in arid and semiarid climates. In Southwestern deserts, it often appears as a tough, dark stain on light-colored canyon walls. Ancient petroglyphs are often found etched into rock varnishes. [...]

Similar rock coatings may exist on Mars because photos returned by every Martian lander show what looks like rock varnish coating the rocky surfaces. However, Kuhlman cautions that these coatings might not actually be rock varnish. [...]

Planetary Science Institute? They must have cool school sweathshirts!

NEOWatcher
2008-Dec-19, 03:40 PM
Revived for news. After a 2-1/2-year sleep.
Is there "news"(as in new information) or is this just a release of a paper from another study?

Ara Pacis
2008-Dec-20, 09:27 AM
Revived for news. After a 2-1/2-year sleep.

Planetary Science Institute press release archive: Rock Varnish: A Promising Habitat for Martian Bacteria (http://www.psi.edu/press/):



Planetary Science Institute? They must have cool school sweathshirts!

The letters, P, S, I in that combination are pretty awesome. Although Planetary Institute of Scientific Study would be pretty awesome too. ;-)

01101001
2008-Dec-20, 02:39 PM
Is there "news"(as in new information) or is this just a release of a paper from another study?

News of the release of a study.

And in the study, there is news of new information about the Chilean rock varnish.

NEOWatcher
2008-Dec-23, 03:20 PM
And in the study, there is news of new information about the Chilean rock varnish.
See, that's my problem. I may not understand the details, but that doesn't mean I wouldn't like to know what new developments there are, or if those developments are limited to interest in the field.
So; from a lay point of view, is there something there, or should I just chalk it up to important points for somebody in that expertise?