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Selfsim
2012-Aug-04, 12:17 AM
So, media excitement leading to Curiosity's landing is picking up and this article serves as well as any other, as an overview summary of the history of the hunt for organics on Mars: Curiosity's search for organics (http://phys.org/news/2012-08-curiosity.html).

Trying to not anticipate too much from Curiosity, is not all together easy, particularly because of the controversy and debate stemming from Viking's findings, and the subsequential McKay speculation based on soil Perchlorates destroying any hypothesised organics during the heating process. Team leader for Viking's GC-MS instrument, Klaus Biemann's refutation of McKay's ideas, also help to bring things back to a balanced outlook. Hopefully, at the very least, Curiosity's findings may progress thinking incrementally …
The following quote provides some background:


Klaus Biemann, leader for the Viking GC-MS experiment, has sharply criticized the perchlorate theory. In a published comment on the Navarro-Gonzalez and McKay paper, he and Jeffrey Bada of the Scripps Institution wrote that the theory is based on faulty data and unfounded extrapolations, and that it ignores the known presence of several cleaning compounds found in the GC-MS during the Viking experiments. They also contend that if the process described by McKay and Navarro-Gonzalez had taken place, that other compounds – in this case other chlorinated aromatic molecules – would also be produced on Mars, yet they were not.

The two agree that meteorites with organic carbon do indeed fall continuously onto Mars, as they do throughout the galaxy. But they argue that the organics are destroyed by high-energy radiation, which in turn leads to a build-up of equally destructive oxidizing agents. Biemann says that the GC-MS instrument used by Curiosity is, in some ways, an advance over the ones on the Viking landers. That’s why, he said, if Curiosity is not able to detect organics, then it becomes ever more apparent that those compounds can’t survive on the Martian surface. “It’s end of story,” he said.
The main instrument package on Curiosity for detection of organics is the Sample Analysis on Mars (SAM) package.
The Principle investigator for SAM, Paul Mahaffy, has some interesting questions:


“Life emerged billions of years ago on Earth and a fundamental question that remains is ‘Did life also emerge on Mars at that time, and if not – why not?’” he said. “If life did emerge at some time, is it still present today? Or was the transformation of Mars so rapid that life could never get a foothold? Curiosity takes important steps toward providing a basis for answering these questions with a detailed study of early martian environments.”I'm not quite sure how much could be learned from a non-organics finding although, I do think it would be a quite a surprise for some.

Its also interesting that the approach seems to be more along the lines of developing an explanation for why organics may not be present … I guess the overall non-life interpretation coming from the Viking findings, has resulted in this approach for Curiosity.

Anyway, let's hope Curiosity makes it alive in one piece and retrieves some solid, reliable data to move things along, one way or the other.

Feel free to use this thread to capture comments on the search for Mars organics as it progresses ..

Regards

Selfsim
2012-Aug-04, 03:16 AM
The analysis of minerals is also being used as a way of inferring past life.

It seems there are approximately 4,600 known Earth minerals1, and two-thirds of known Earth minerals are thought to be formed due to interactions amongst rocks, atmosphere and life.

Mars may not have had a chance to evolve in this same way, so it is not expected to find new minerals (beyond those already known). Nonetheless, if these are detected, Curiosity's instruments should be able to determine their chemical makeup.

According to The Definition of a Mineral (http://www.minsocam.org/msa/ima/ima98(04).pdf) by E.H Nickel (1995), the organic mineral class includes biogenic substances, in which geological processes have been a part of the genesis or origin of the existing compound:

Biogenic Substances.
Biogenic substances are chemical compounds produced entirely by biological processes without a geological component (eg: urinary calculi, oxalate crystals in plant tissues, shells of marine molluscs, etc) and are not regarded as minerals. However, if geological processes were involved in the genesis of the compound, then the product can be accepted as a mineral. Examples of acceptable minerals of this kind are substances crystallized from organic matter in black shale or from bat guano in caves, and the constituents of limestone or phosphorites derived from marine organisms.

Images and spectroscopic analyses taken from orbit around Mars by the UA-operated HiRISE camera, have identified minerals at the bottom of Gale Crater, such as clays and sulfates which on Earth, require liquid water to form.

The top level classifications of organic compound minerals are listed here. (http://www.mindat.org/dana.php?a=50) The more detailed breakdown of their composition and how they are formed, is provided by following the links.

I have a feeling we'll be hearing a lot more about all this once Curiosity gets underway with its geological analysis.

Regards

Notes:
1. There are approximately 4,000 according to the International Mineralogical Association. (http://en.wikipedia.org/wiki/Minerals)
Downs and Morrison, (http://phys.org/news/2012-08-robotic-geologist-mars.html) (members of Curiosity's CheMin science team), have collected about 2,200 species samples in their lab .. which houses the greatest number of mineral samples in the world. It will be used as the reference database for analysing Curiosity's samples.

Selfsim
2012-Aug-04, 10:39 PM
Just for the record, a BAUT member with extensive geology experience (JESMKS) recorded the view that Spirit may have already discovered a deposit of diatomaceous earth (Gertrude Weise - almost pure opaline silica). Some discussion took place in this thread (http://cosmoquest.org/forum/showthread.php/126025-How-would-the-discovery-of-life-on-Mars-effect-our-society?p=1976377#post1976377) (starting at post #84). NASA apparently decided that particular find to be a sinter deposit … (and according to JESMKS, with apparently, not a lot of justification for eliminating organic origins (??) ).

This seems to be why Curiosity has been designed to look in detail, at the immediate surroundings of particular samples. In Earth-based geology, where the sample is found, and in particular, under what surrounding geological conditions, is what enables firmer conclusions to be formed. Just like life itself, its not just the presence of raw chemical compounds and their physical signatures which distinguish 'subtle' microbial life (for eg). Even less reliable, is using simple compounds as an inference of metabolic by-products … (which is what makes remote detection so open to doubt).

In the case of Earth-based geology, historical evidence-based records including a database of 'organic mineralogy', and simplistic, stable past processes, enables the piecing together of a plausible geological history, with probably universal applicability. The greater degree of complexity involved in biological processes, and absence of historical details pertaining to abiogenesis, sensitivity to environmental changes over time, and a lack of detailed knowledge of initial conditions, makes using the same process, virtually infeasible for predicting life elsewhere.

In some cases, the direct detection of past life from organic compound minerals can be conclusive, and thereby, could also be used to incrementally accumulate data on the numbers of: (i) instances of no-life with organic minerals and (ii) life with organic minerals (biogenic). Such instance data over many samples, may also lead to valid statistical inference methods for predicting the prevalence/absence of hypothesised exo-life.

In other cases however, structures within the samples can lead to misinterpretation, such as the 2002 announcements of Mars life being found in the ALH84001 meteorite, (http://en.wikipedia.org/wiki/Life_on_mars#ALH84001_meteorite) due to it exhibiting the appearance of terrestrial biological magnetite. Claims of fossilized nanobacteria have also been made from the Nakhla Meteorite. The Shergotty meteorite is also composed of pyroxene and is believed to contain signs of microbial communities. The presence of hematite is also considered to be an 'indicator'. Much of this analysis is dependent on pattern matching from the sample structures, and is heavily reliant on how this all works on Earth .. with its abundance of already entrenched water-based, C12-isotope-enriched life.

Has this fossilised meteorite evidence resulted in instruments on Curiosity being designed to eliminate any remaining doubts ? If so, then what implications would the possibility of an overall 'no-fossilised-life-detected' conclusion have ? Would this carry the same scientific weight as the opposite 'fossilised-life-detected' conclusion ?

It might take a while for the end results, but provided Curiosity arrives in a fully operational condition, the conclusions able to be formed from the physical and chemical analysis data, will certainly be invaluable to the advancement of real science … provided we listen from an unbiased perspective.

Regards

publiusr
2012-Aug-06, 09:44 PM
I wonder if the skycrane crash site should be investigated. The impact of the skycrane upon the Mars rock below, would impart enough force to shatter larger stones and open them up for study.

Then too, the fuel (hypergolics?) from leaking tankage may contaminate results. On the other hand, the oxidizer might eat away at things in a useful way. The rover itself cannot impart enough force on rock for more than a tiny amount. The brute force of the skycrane impact, or the backshell, might allow for freshly broken bits to inspect.

R.A.F.
2012-Aug-06, 09:55 PM
I wonder if the skycrane crash site should be investigated. The impact of the skycrane upon the Mars rock below, would impart enough force to shatter larger stones and open them up for study.

Then too, the fuel (hypergolics?) from leaking tankage may contaminate results.


As I understand it, they will "steer clear" of the skycrane...don't know if it's contaminates, or some other reason for avoiding it.

Selfsim
2012-Aug-06, 10:18 PM
Hmm .. interesting strategy there publiusr ! Some of the rocks of interest may not need breaking open though … for example:

I read a report today, (http://phys.org/news/2012-08-varnish-clues-life-mars.html) on how some think that rock varnish may be formed, (on Earth), as a direct result of large congregations of micro organisms. (There are also similarly coated looking rocks discovered by Spirit in 2006 on Mars. The one in the photo looks like its already been broken open ...):

All life on Earth needs manganese to carry out biological functions,” Barry E. DiGregorio at the University of Buckingham in the UK told Phys.org. “The microorganisms involved in forming manganese-rich rock varnish in the samples we examined likely absorbed it from atmospheric dust, water vapor and other forms of precipitation - all available on Mars."Then again, somewhat unfortunately, Curiosity doesn't have the technology to detect any fossilised diatoms (etc) in the varnish coatings:

Once ChemCam/LIBS determines whether a rock coating is composed of manganese, the rover could then travel up to the rock, scrape a small sample and place it in the SAM organic analyses instrument to see what organic compounds exist. Unfortunately, none of the microscope instruments on Curiosity or sent to Mars previously had the ability to resolve bacteria. To do this would require sending a microscope that could ‘see’ something as small as 1 or 2 microns.”
Its also interesting to note:
The researchers acknowledge that their observations here have an important limitation, which is that just because a form has the right size and shape to be a microorganism, it doesn’t prove that the forms are microorganisms. Despite this uncertainty, they note that it would be difficult to explain the New York rock varnish formation through abiotic processes.I wonder whether that particular difficulty is more an indicator of our lack of knowledge of 'other planet' geological processes, (which could still conceivably make rock varnish in abiotic conditions) ? After all, manganese is just another free element in nature ?

Regards

djellison
2012-Aug-07, 01:50 PM
I wonder if the skycrane crash site should be investigated.

No. It was intentionally discarded to the WNW of of the rover ( it could fly away fwd or backward, and the rover was to choose whichever of those was most northerly. Turns out backwards, at a bearing of about 292deg )

THey will not be driving to see it. It offers far too much potential risk to the rover.

mutleyeng
2012-Aug-11, 12:46 AM
not sure how seriously we should take this article yet
http://www.sci-news.com/space/article00523.html

Plate tectonics found on Mars? that would be pretty big news right?

Noclevername
2012-Aug-11, 01:13 AM
Plate tectonics found on Mars? that would be pretty big news right?

If it can be confirmed, it would be big news.

mutleyeng
2012-Aug-11, 01:38 AM
I picked up the story via seti institute - if confirmed, it would seem to imply plate tectonics could be common, 2 for 2 on rocky planets with surface water - often considered highly desirable for life

iquestor
2012-Aug-11, 02:06 AM
plate tectonics was one of the criteria Ward and Brownlee (Rare Earth) posited for life, their point being it was probably a rare planetary feature. If this is true then it should mean its fairly common.

Go Life!!!!

publiusr
2012-Aug-11, 06:58 PM
No. It was intentionally discarded to the WNW of of the rover ( it could fly away fwd or backward, and the rover was to choose whichever of those was most northerly. Turns out backwards, at a bearing of about 292deg )

THey will not be driving to see it. It offers far too much potential risk to the rover.

I kinda wish the drop zone was closer to Mt. Sharp. Had the skycrane flown into the flank of the mountain, then cartwheeled down the different strata--knocking rocks from different layers off as it went--the rover would have fresh rocks rolling around at ground level there on the crater floor to inspect rather easily. A Martian LCROSS, if you will.

That might be something to keep in mind for later missions.

Selfsim
2012-Aug-11, 11:00 PM
Does anyone know the location of Curiosity relative to An Yin's plate boundaries ?

'Twould be interesting to get some data on the geology within the vicinity of where he thinks the boundary regions are

I notice that according to the article, An Yin is the sole author of the article … perhaps we should wait and look for others wiling to accept his ideas before taking it further ?

Cheers

Paul Wally
2012-Aug-13, 04:26 PM
If there is plate tectonics on Mars, shouldn't there be some earthquakes, I mean marsquakes. Are there any instruments on Curiosity or past rovers for measuring seismic activity on Mars?

mutleyeng
2012-Aug-13, 05:10 PM
Best as I could find (which means i could easily be wrong) there were seismometers on The Viking landers. The instrument on viking 1 didnt work - on viking 2 they did get a reading of what might have been a marsquake, but not sure just how good that data is considered to be.

publiusr
2012-Aug-13, 11:01 PM
Glad Curiosity didn't land on the Viking sites. Gale has about the smoothest terrain I've seen on Mars yet.

Paul Wally
2012-Aug-13, 11:41 PM
Glad Curiosity didn't land on the Viking sites. Gale has about the smoothest terrain I've seen on Mars yet.

Indeed quite smooth, but just ahead towards Mt. Sharp there is this dune field with the dark sands and beyond that some pretty challenging terrain (small mesas with what looks like vertical cliffs). I don't know how far those areas are and whether they are actually inside the landing ellipse, but imagine the mess the skycrane thrusters would have made with those sands.

More relevant to the topic, does anyone know what the chemical composition of those dark sands is? I suppose they're not carbon based organics :)

Selfsim
2012-Aug-14, 01:58 AM
Indeed quite smooth, but just ahead towards Mt. Sharp there is this dune field with the dark sands and beyond that some pretty challenging terrain (small mesas with what looks like vertical cliffs). I don't know how far those areas are and whether they are actually inside the landing ellipse, but imagine the mess the skycrane thrusters would have made with those sands.

More relevant to the topic, does anyone know what the chemical composition of those dark sands is? I suppose they're not carbon based organics :)Phyllosilicates ? (At ~22 kms distant .. 30 Sols drive). (If not, the geology of the terrain outlook was posted by ToSeek in the Curiosity Surface Operations thread. The NASA PDF presentation is here. (http://marsoweb.nas.nasa.gov/landingsites/msl/workshops/5th_workshop/talks/Tuesday_AM/Anderson_Gale_Traverse_compressed_final_opt.pdf)

Looks like the composition of the 'dark dunes' (18.7 kms distant .. after 210 Sols) is presently unknown also .. and up to Curiosity to figure out.
Interesting ...

Cheers

mutleyeng
2012-Aug-14, 02:45 AM
there is a special talk this friday 17th 20:00 UTC at the seti institute that might be of interest to some following this thread.

The Imaging group at MSSL, UK’s largest university-based space research group, has been developing life detection systems for application to Mars as part of the European Aurora programme. The starting point is the PanCam for ExoMars 2018 rover, and possible follow-on missions for sample-return with our new partners in Russia. A data fusion approach has been developed to combine orbital and ground-level panchromatic and hyperspectral imagery with targeted observations of potential life habitats such as subsurface samples, cliff overhangs and cave entrances using UV-stimulated imaging
xamples will be shown of the automated extraction of 3D terrain and associated terrain-corrected 3D information from spaceborne as well as rover camera data to produce a multi-resolution 3D environment to show "a posteriori" what areas have been imaged at different resolutions from MER and in future MSL Curiosity within the PRoGIS system.

live viewers can ask questions in the youtube comments

Selfsim
2012-Aug-16, 11:46 PM
So, yet another theory on how one might recongise signs of microbial activity published recently in Geology:

Biosignatures link microorganisms to iron mineralization in a paleoaquifer (http://geology.geoscienceworld.org/content/40/8/747.abstract)

The idea being that round, primarily sandstone, 'Moqui Marble' type rocks, which have a hard outer iron oxide shell, have been found to have had what looks to be microorganisms at play in the formation of the iron oxide:

An easier read is here. (http://phys.org/news/2012-08-unl-discovery-implications-life-earth.html)


With limited organic carbon or light to feed on, microorganisms instead used siderite, a mineral containing iron carbonate, as an energy and carbon source, a process that oxidized the iron and turned it into iron oxide. It also produced acid, which dissolved the iron carbonate into iron and carbonates that dispersed to the mineral's exterior lining. The process continued until a thick shell of iron oxide formed, leaving a bleached sandy core containing little iron. Microorganisms further converted the inorganic carbonates into organic carbon.

To determine that microorganisms were involved, researchers looked for telltale signs of life, principally nitrogen and organic carbon. Compared to minerals, living beings usually contain a "lighter" isotope of carbon, or one with fewer neutrons, and chemical analyses indicated the presence of this lighter carbon. Looking at the material using a field emission scanning electron microscope, they discovered structures that resembled microorganisms.
So examining 'sedimentary-looking' rocks with iron oxide outer shells on Mars may produce structures which resemble microorganisms. (This one sounds very similar to the AL 84001 meteorite example in post #3).

So, I guess we should prepare for seeing some images of things which may very well resemble micro-organisms on any such Mars rocks.

Curiosity has the tools to be able to detect this kind of thing, should it have happened on Mars .. but the key determining evidence in the Earth-related example was the C12/C13 ratio used to detect the past activity of our type of life. This characteristic is only known to be exhibited for Earth-life … such a test on Mars might not return the same consistency of results on Mars, however. Forming conclusions about the presence/absence of life on Mars as a result of such a test, might be very difficult.

I guess we'll have to wait and see where the Mars test results might lead …

The closing comments are also of interest:

This allows for a target that can be identified more easily than having to search at the fine scale, such as looking for DNA, Weber said.So, just because things might look like microbial activity, doesn't mean its actually been found, eh ?

Curiosity doesn't have any bio-chips for DNA detection onboard .. (pity).

Regards