MSL scientific results Options

[HughFromAlice]

Been busy with other things for a while, so it's nice to be back and see all the photo imaging work on the site going from strength to strength

I think a lot of you guys would really enjoy "Curiosity On Mars:First Results" 3 part x approx 2 hr presentations at the EuroGeosciences Union General Assembly published on the EGU Channel on YouTube on May16th. Plenty of good listening for the weekend! Although I enjoy the NASA press briefings, it's great to hear key mission scientists talking full-on to their peers. The talks travel along at a nice fast thought provoking pace!

http://www.youtube.com/watch?v=hPbbhfGg0nc

Admin: Moved post from 'First Drill' thread.

[Paolo]

at long last, the first two peer-reviewed papers on Curiosity's scientific results!

Martian Fluvial Conglomerates at Gale Crater
Measurements of Energetic Particle Radiation in Transit to Mars on the Mars Science Laboratory

[nprev]

0.66 Sv +/- 0.12...ouch. Not good.

[imipak]

A story by Jonathon Amos on the BBC news site about the Fluvial Conglomerates paper, with a great interview with Sanjeev Gupta:
http://www.bbc.co.uk/news/science-environment-22708902

[Jimbo1955]

0.66 Sv +/- 0.12...ouch. Not good.

About what the highest dose received by a Fukashima worker obtained.

[dvandorn]

MSL's cruise phase took place as the Sun was ramping up to an activity peak in its 11-year cycle. And as I recall, we've seen a somewhat unusually active ramp-up this time around. Perhaps radiation-sensitive payloads may have to take advantage of transfer orbit windows that occur during quiet sun periods?

-the other Doug

[mcaplinger]

Perhaps radiation-sensitive payloads may have to take advantage of transfer orbit windows that occur during quiet sun periods?

The paper says that only about 5% of the total dose MSL saw in cruise was from solar events, the rest being from galactic cosmic rays. GCR dose rate is thought to be weakly anticorrelated with the solar cycle.

They do point out that "the SEP contribution could conceivably be many times larger in a different time frame" (i.e., closer to solar max.)

[atomoid]

not to get too OT here, but here's some interesting info on the topic and additional flashes of inspiration
"..The computers recover with a reboot; the cameras suffer permanent damage. After about a year, the images they produce look like they are covered with electronic snow.."

[Gerald]

Those flashes are mostly caused by Cerenkov radiation, when charged particles move faster than light moves in the same medium (phase velocity), however slower than vacuum speed of light, of course. (Light moves slower in most media than in vacuum; speed of light is dependend of wavelength in media.)

The main challenge associated with high-energy cosmic rays isn't the Cerenkov radiation, but a cascade of particle-antiparticle pair production resp. (hadronic) showers of secondary particles.
Therefore a shielding can multiply the radiation caused by a GCR hit.
The resulting question is, how to design a shielding that reduces solar energetic particles (SEP), and doesn't multiply GCR-induced secondary radiation too much.

[Gerald]

... one idea to circumvent this dilemma is a dynamic shielding, because most of SEP radiation occurs in peaks: SEP graphics in JPL Photojournal.
Thin shielding during low SEP activity to avoid secondary particles caused by GCRs; thick shielding during SEP peaks, detected by instruments, or presumed by forecast.

That's a transfere of the answer given in the recent telecon 0:47:09 to 0:49:16 to robotic missions.

[Paolo]

another batch of MSL results in Science
Isotope Ratios of H, C, and O in CO2 and H2O of the Martian Atmosphere
Abundance and Isotopic Composition of Gases in the Martian Atmosphere from the Curiosity Rover

[Marz]

fyi: The upcoming Geological Society of America's annual meeting has a few sessions dedicated to MSL:

T1. CURIOSITY AT GALE—PAST AND PRESENT ENVIRONMENTS OF MARS

LATE JURASSIC ROCKS OF THE COLORADO PLATEAU AS DEPOSITIONAL AND DIAGENETIC ANALOGS TO GALE CRATER, MARS

There's also a session on Mercury, Icy Worlds, Lunar Water, and comparison of Saharan and Mars dunes.

[Don1]

fyi: The upcoming Geological Society of America's annual meeting has a few sessions dedicated to MSL:

T1. CURIOSITY AT GALE—PAST AND PRESENT ENVIRONMENTS OF MARS

I skimmed through the abstracts. Here are some quotes.

* "fluvio-lacustrine sedimentary rocks (showing some signs of volcanic influence), known as Yellowknife Bay formation, which could be as young as middle Hesperian to even early Amazonian."

* " a habitable subaqueous sedimentary environment that persisted from 100’s yrs to 10’s Kyrs. "

* " influence of at least two generations of fluids."

* "Curiosity has observed abundant evidence of geologically recent surface modification at the Gale crater landing site"

* "The flagstone-type fracture pattern, mudstone lithology, presence of swelling clay, and occurrence in a dominantly sedimentary sequence suggest that the polygonal fracture pattern of the Glenelg Regionare formed by desiccation in a drying playa...A possible change in climate resulted in drying of the lake, exposure of mudstones, and formation of desiccation cracks. "

* "ET-THEN: A POSSIBLE MARTIAN MAGMA?"

* " these data suggest late occurring, local alluvial activity on some fans...the timing of possible late alluvial activity in Gale correlates with alluvial activity in Margaritifer Terra hypothesized to result from melting snow...water would have drained downslope and could have contributed to development of late diagenetic features observed by Curiosity in the rocks at Yellowknife Bay."

* "The Yellowknife Bay formation has been split into four members (from base to top): the Sheepbed, Gillespie Lake, Point Lake, and Shaler members. The clay-bearing mudstones of the basal Sheepbed member suggest suspension settling in a distal alluvial or proximal lacustrine setting. A sharp contact traceable in orbital images for hundreds of meters separates the Sheepbed member from the Gillespie Lake member. The Gillespie Lake member consists of sheet-like beds of poorly sorted medium- to coarse-grained sandstone. The lateral continuity of these beds and the lack of channel bodies in the Gillespie Lake member indicate deposition in distal fan lobes. Overlying the Gillespie Lake member is the Point Lake member, characterized primarily by the presence of centimeter-scale vugs. Both volcanic and sedimentary interpretations are being considered for this enigmatic member. The overlying Shaler member consists of coarse-grained trough cross-bedded sandstone and pebble beds and recessive finer-grained intervals consistent with a fluvial environment dominated by bedload and suspended load transport. A set of diagenetic features observed throughout the Yellowknife Bay section suggests a complex aqueous history involving multiple phases of alteration. "

* "they also contain late diagenetic calcium-sulfate filled fractures that relate to their burial history... hydraulic fractures in YB mudstones attest to substantial burial and vertical movement of evolved brines from underlying or laterally adjacent strata."

[CosmicRocker]

Thanks for the nice summary.

[Den]

0.66 Sv +/- 0.12...ouch. Not good.

According to en.wikipedia.org/wiki/Background_radiation, average exposure in USA is 0.006 Sv/yr. There are several inhabited places on Earth with ~100 times more natural background - making 0.66 Sv/yr not as "ouch" as it looks at the first glance.

[Robotbeat]

According to en.wikipedia.org/wiki/Background_radiation, average exposure in USA is 0.006 Sv/yr. There are several inhabited places on Earth with ~100 times more natural background - making 0.66 Sv/yr not as "ouch" as it looks at the first glance.

Indeed, it's almost exactly in line with other estimates of radiation from GCR in deep space. Lithium hydride, by the way, is quite effective (i.e. good shielding per mass, low secondary production) given the low atomic masses, about even with methane (though LiH is solid and denser, both good) and better than basically everything else except liquid hydrogen. Aluminum is horrible. It may even make things worse in some cases.

I'd like to see what the total levels are at the surface. It should be less than half the deep space level, and it should depend on altitude.

I came here looking for figures on the surface radiation level measured by the RAD instrument. Anyone have them?

[Greenish]

Well, you could just go here & process it yourself: http://ppi.pds.nasa.gov/search/view/?f=yes...PPI/MSLRAD_1002

But so as not to be rude, I did look around and there don't appear to be any peer-reviewed or significant public data on the surface radiation measurements. Best I could find is actually a nice summary, in the most recent PPT file (26MB) on this page: http://mslrad.boulder.swri.edu/educators.html which does have some decent (preliminary) surface info starting at slide 35, with dosimetry info on 45-47.

Bottom line is 1.84 +/-0.30 mSv/day in cruise and 0.7 +/- 0.17 mSv/day on surface. Don't want to go into implications because this is not a human spaceflight forum.

To keep this planetary-science relevant: they also have some neat charts showing the variations of charged particles and neutron dose (oppositely correlated) with pressure each sol, and comparisons with GCR spectra.

[Paolo]

A new MSL pre-print in Science Express today: Low Upper Limit to Methane Abundance on Mars

[Explorer1]

It looks more and more likely that methane emissions are highly localized, dependent on wind, temperature, etc. to spread across a wide area.
We may have to wait for dedicated instruments (on Mangalyaan) and missions (Exomars Trace Gas Orbiter) to show which places it occurs. Then would come a lander, and ground truth would follow.

[marsbug]

Barring instrument faults on either the rover or orbiter in question, three scenarios pop into my head: Either the methane is somehow very well isolated to a higher region of the atmosphere, the lifespan of methane in the martian atmosphere is much shorter than previously believed, or some unrecognised factor in the equation has changed. Could Mars Express re-take the atmospheric methane measurements?

[Phil Stooke]

A fourth scenario occurs to me. The methane doesn't exist.

Phil

[Explorer1]

Yes, that is technically possible as well. It would mean the Mars Express and Earth observations are somehow flawed.

[siravan]

The earth based observations were always somewhat suspect, because they had to account for the methane in earth atmosphere, which was estimated based on some models. The end result was subtracting two large numbers and showing the difference was small, but different from zero.

[djellison]

There are good reasons to doubt both the ground and the MEX PFS based observations - this paper takes them to task thoroughly.
http://faculty.washington.edu/dcatling/Zah..._CH4_Doubts.pdf

[nprev]

Given that methane decomposes rapidly when exposed to UV this finding to me implies that any methane in the atmosphere (if there ever is a significant amount of it) is very transient, and most likely related to occasional geological events.

We need a couple of seismometers on Mars BAD.

[mcaplinger]

Given that methane decomposes rapidly when exposed to UV this finding to me implies that any methane in the atmosphere (if there ever is a significant amount of it) is very transient...

Are you suggesting that there was methane when MEx looked, but there isn't any now? The lifetime of CH4 in the atmosphere is short, but not that short (hundreds of years.)

Occam's Razor suggests something other than transience.

[Explorer1]

Well, Insight's arrival will tell us a great deal more about the geological processes, if any, that continue. Like I said before it would be best to wait for the dedicated trace gas hunters and their results to weigh in conclusively on causal factors.

[ngunn]

It's a long shot, but there is one other way to reconcile detection of a substance from the outside but not at the surface. We are talking about very small quantities. Perhaps it is present in the upper atmosphere but not lower down. How much mixing is there? Maybe it forms at altitude and is quickly desroyed there. Maybe it arrives from comets?

[nprev]

Are you suggesting that there was methane when MEx looked, but there isn't any now? The lifetime of CH4 in the atmosphere is short, but not that short (hundreds of years.)

Occam's Razor suggests something other than transience.

Not implying that, and I agree. I think that any significant amount of methane from ongoing seismic activity would result in a concentration well above what was observed by MSL. However, there may be VERY local and small-scale releases from inorganic sources from time to time.

Biggest bummer here to me is that this finding also presumably constrains the possibility of hot springs; that's been something I'd hoped we'd find somewhere someday. Looks even more unlikely now.

[serpens]

If the ground based / Mars Express methane measurements were correct then we would have the really weird scenario of highly concentrated (for Mars) local releases of methane in limited areas over an exceedingly short timeframe that then just as mysteriously disappeared due to some unknown process unique to Mars. No known process could remove methane with an efficiency so much greater than on Earth where the efficiency of methane loss should be far greater. The interpretation of the data has been the subject of vigorous debate for some years and now Curiosity has again shown the advantages of ground truth.

[marsbug]

A fourth scenario occurs to me. The methane doesn't exist.

Phil

...or the methane doesn't exist.

[Don1]

This whole Martian methane business seems like a modern day version of the controversy over Martian canals that took place 100 years ago. It is a question of people seeing what they hope to see at the limits of instrumental resolution.

[marsbug]

After all the effort and money invested in Mars exploration over the last fifteen years or so it is easy to see why people would want to find some possible evidence of extant life. I'm just hoping that a negative result on methane today won't hurt the will to explore Mars's deep past, and I think that should be my last word before this drifts any further from topic.

[Paolo]

several MSL papers in today's Science.
Analysis of Surface Materials by the Curiosity Mars Rover
Soil Diversity and Hydration as Observed by ChemCam at Gale Crater, Mars
X-ray Diffraction Results from Mars Science Laboratory: Mineralogy of Rocknest at Gale Crater
Volatile, Isotope, and Organic Analysis of Martian Fines with the Mars Curiosity Rover
The Petrochemistry of Jake_M: A Martian Mugearite
Curiosity at Gale Crater, Mars: Characterization and Analysis of the Rocknest Sand Shadow

Curiosity even made it to the cover!

[Harder]

Paolo, in the last hour or so Curiosity also made it to the "Breaking News" level: 2% water in soil. See also http://www.bbc.co.uk/news/science-environment-24287207

[CosmicRocker]

It would be interesting to learn of the details regarding this measurement. Is the water being held by hygroscopic salts in the soil, or as water of crystallization in some mineral, or as something else?

[Gerald]

The abstract X-ray Diffraction Results from Mars Science Laboratory: Mineralogy of Rocknest at Gale Crater, Paolo pointed to, mentions hisingerite (Fe₂Si₂O₅ (OH)₄ · 2H₂O) as an option:

The soil also contains ... volatile-bearing phases, including possibly a substance resembling hisingerite

[marsophile]

... or as water of crystallization ...?

The paper seems to conclude that the volatiles are almost entirely contained in the amorphous component.

[serpens]

I think the consensus was that this was bound water within the samples amorphous component.

[t_d]

Is it possible that a small amount of this water could be set free by the pressure or the heat generated by the action of the drill on the rock or soil?
TD

[t_d]

Btw would someone point me the set of all the drill sample results. We must be at a bunch now, right? I've just been too busy to follow closely - sorry.

[Phil Stooke]

Remember the drill was not used at Rocknest, so it didn't release water.

Detailed results on drill samples are still to be published.

Phil

[t_d]

Thanks! I'm sure lots of folks are looking forward to the results as much as I!
I'd always wondered if one of the images of the repeated impact of the drill into
rock on the first group of attempts left a tiny sliver of water at the bottom of the
tiny crevasse.

[Astro0]

The short answer to that question would be 'no'.

[serpens]

Interesting that the ChemCam analyses did not reveal any significant exchange of water vapour between the regolith and the atmosphere. Significant is another of those unfortunate rubbery words but the finding reflects the Phoenix TECP outcome. This would seem to constrain the diurnal exchange hypothesis. Comparison of the delta D of the current atmosphere, the sample and of SNC meteorites could possibly provide an insight into the age of the sample material .

[DEChengst]

Full papers now up on the JPL site:

Analysis of Surface Materials by the Curiosity Mars Rover.
Soil Diversity and Hydration as Observed by ChemCam at Gale Crater, Mars.
X-Ray Diffraction Results from Mars Science Laboratory: Mineralogy of Rocknest at Gale Crater.
Volatile, Isotope, and Organic Analysis of Martian Fines with the Mars Curiosity Rover.
The Petrochemistry of Jake_M: A Martian Mugearite.
Curiosity at Gale Crater, Mars: Characterization and Analysis of the Rocknest Sand Shadow.

ADMIN: Links edited to include titles of papers.

[Don1]

AGU abstracts are now available online here. (Link edited and fixed. Thanks Phil!)
There's a lot there. For instance:

"Sedimentary rocks of the YBF [Yellowknife Bay Formation] preserve a remarkable diversity of diagenetic textural features. These features can be roughly subdivided into at least two phases of activity: (1) formation of early concretions, voids, and internally banded ridges, potentially associated with a set of redox reactions that may have produced gases of, as yet, unknown character, and (2) later precipitation of Ca-sulfate (anhydrite, bassanite, and perhaps gypsum) in veins and in early diagenetic voids that are cross-cut by veins."

"Title: Raised Ridges in the Sheepbed Member as Evidence for Early Subaqueous Diagenesis at Yellowknife Bay
Spatially restricted clusters of erosion-resistant, ridged fracture fills have been found throughout the fine-grained clay-rich Sheepbed member of the Yellowknife Bay Formation ... these are interpreted as early diagenetic synaeresis cracks, likely formed by gas expansion... the fracture-filling also occurred subaqueously, in the phreatic zone, and was likely a very early diagenetic process"


"TITLE: The Mineralogical and Chemical Case for Habitability at Yellowknife Bay, Gale crater, Mars
...The presence of Fe and S in both reduced and oxidized states represents chemical disequilibria that could have been utilized ...Saponitization of olivine (a process analogous to serpentinization) could have produced H2 in situ. Indeed, early diagenetic hollow nodules (“minibowls”) present in the Cumberland mudstone are interpreted by some as forming when gas bubbles accumulated in the unconsolidated mudstone... A rough estimate of the minimum duration of the lacustrine environment is provided by the minimum thickness of the Sheepbed member. Given 1.5 meters, and applying a mean sediment accumulation rate for lacustrine strata of 1 m/1000 yrs yields a duration of 1,500 years. If the aqueous environments represented by overlying strata are considered, such as Gillespie Lake and Shaler, then this duration increases."

And: "A potential analog for the Sheepbed smectite is ‘griffithite,’ a variety of trioctahedral smectite in altered basalt of the Topanga formation, Griffith Park, Los Angeles."

I love the irony of sending Curiosity all the way from Pasadena to Gale Crater, only to find the same rocks as are present a short drive away in Griffith Park.

[Phil Stooke]

Use this link - Don1's seems to be tangled up with his logon info so it rejects direct access.

http://fallmeeting.agu.org/2013/scientific-program-2/

Phil

[Explorer1]

RAD telecon starting soon:
http://www.nasa.gov/news/media/newsaudio/i...ml#.UqYDVOKp6Fh

[Greenish]

Well, I missed the telecon, but if this is the press release to go with it there was a lot more that just RAD!

NASA Rover Results Include First Age Measurement on Mars and Help for Human Exploration

http://www.sciencemag.org/content/early/recent has the 6 papers under today's date.

(EDIT: changed 1st link to point to JPL page instead of nasa.gov; EDIT2: 1st link fixed)

[Gerald]

The first link contains a trailing %22; it should be
NASA Rover Results Include First Age Measurement on Mars and Help for Human Exploration

[ngunn]

Thanks for those links. Rock dating by a robotic probe is a big landmark in solar system exploration. The better the robots get the less need there is for sample return.

[Tom Tamlyn]

This is exciting. I've noticed some stories in the last couple of years about rock dating instruments under development for future missions, e.g. here, and especially here.

But as the middle ages roll on, one starts to curb his enthusiasm about instruments in development for hypothetical future missions. It's an unexpected treat that currently roving hardware can do this.

TTT

[Gerald]

I've been hoping that the K-Ar method could work without been anticipated before landing. So this is a really exciting success. (Btw.: It has been discussed at UMSF years ago.)
Narrowing down locations of low cumulative radiation exposure could result in even more exciting results; can't wait for the first SAM analysis of the next drill tailings (at WP4).

The MSR question is certainly highly controverse (rule 1.2?).

[ngunn]

What amazes me is that the particles that constitute the mudstone are still so big that a negligible amout of argon has escaped from their sufaces, allowing a crystallisation date to be derived for the progenitor rock. I would have expected some of that argon to have got out somehow, with all the physical and chemical processes those grains have undergone. How small do particles have to be before we can't do this? Can we get a crystallisation age for the material that forms Martian dust?

[Gerald]

K-Ar dating:

When K-40 decays to Ar-40 (Argon), the atom typically remains trapped within the lattice because it is larger than the spaces between the other atoms in a mineral crystal.

Based on this, you can well go down to the nanoscale, unless the surface doesn't get too large in comparison to the volume.
Things get a little more complicated, whenever the crystal lattice is destroyed, but the argon can't escape, and part of it is trapped again in new crystals.

The main uncertainty in the recent measurements seems to not have been caused by the argon, but by the limited accuracy of the amount of potassium.

Single interstellar dustgrains have been analysed. I'm unaware of K-Ar dating of dust.

[Gerald]

Links to the six December 9 papers, abstracts and full text.
You can also get there via Emily's post, but it's more direct this way.

[Reed]

Passive ChemCam observations have come up a few times. It appears there is a recent paper on this
ChemCam passive reflectance spectroscopy of surface materials at the Curiosity landing site, Mars (paywall, but googling the title should find you a PDF on the chemcam site)

The ChemCam publications page has a bunch more recent papers and preprints.

[TheAnt]

Researcher claim MSL images show "Earth like soils" suggestive of more benign conditions on Mars in the ancient past.

Univ of Oregon media relations page.

[Eutectic]

Published evidence for more differentiated igneous rocks:

Date:
July 14, 2015
Source:
DOE/Los Alamos National Laboratory
Summary:
The ChemCam laser instrument on NASA's Curiosity rover has turned its beam onto some unusually light-colored rocks on Mars, and the results are surprisingly similar to Earth's granitic continental crust rocks. This is the first discovery of a potential 'continental crust' on Mars.

DOE/Los Alamos National Laboratory. "Curiosity rover finds evidence of Mars' primitive continental crust: ChemCam instrument shows ancient rock much like Earth's." ScienceDaily. www.sciencedaily.com/releases/2015/07/150714142051.htm (accessed July 15, 2015).

[TheAnt]

Thank you for posting that one Eutectic, I had already read it, and if I had not been seated safely I could have fallen over in surprise.
Trondheimite type granite found on Mars! I am far from a specialist, many hobby geologists could quite likely teach me things, even so I know this is a major find.

[dvandorn]

Yes! This is an amazing find. Granites are thought to have formed on Earth when hydrated crust (read: seafloor) is subducted during plate tectonics. Now, trondhjemite (and the TTG suite in general) doesn't necessarily show the chemical signatures of having directly re-mixed with mantle material, so finding the stuff on Mars doesn't absolutely prove that Mars had what we would recognize as plate tectonics. It's a pretty sure sign that some crustal subduction of highly hydrated rocks did occur, though, of some type.

Unless, of course, this is an example of a piece of Earth's Archaen crust that was whacked into space by a big impact and transported to Mars, just as Martian meteorites have been found on Earth. That would seem to be less probable than Mars creating its own granites, though, I think.

-the other Doug

[monitorlizard]

Granite (the author uses the term granitoid) rocks were found on Mars by a combination of MGS TES and Mars Odyssey THEMIS data going back to papers from 2004 and 2006 by Bandfield. The locations were in the Syrtis Major region (61.8 Lat,-65.9 E Long and a second location whose description is a bit screwed up in my source). The key paper is:

Bandfield, J.L. Extended surface exposures of granitoid composition in Syrtis Major, Mars. Geophys. Res. Lett. 33, doi:10.1029/2005GL025559, 2006.

Finding granite in Gale Crater would extend the area of extent of granite on Mars, a very welcome discovery. My source was "The Martian Surface" book edited by Jim Bell, which was published in 2008. CRISM may or may not have found additional exposures since then, I don't know. I think thermal infrared works better for finding granite's minerals than CRISM's spectrum, though.

[monitorlizard]

Oops! I completely misread the coordinates of the granitoid exposures in Syrtis Major. The correct description of the location is that there are two exposures contained within a single area that is bounded by a line running from 61.8 to 65.9 degrees East longitude and a line running from 18.4 to 20.5 degrees North latitude. By the way, the total area of exposures with significant concentrations is 19 square kilometers.

Sorry for the screw up.

[Julius]

A paper in Science magazine issued 9th October on paleoclimates and lacustrine environment in gale crater. Don't have link. Do not have free access to it I m afraid!

[Paolo]

A paper in Science magazine issued 9th October on paleoclimates and lacustrine environment in gale crater.

here it is:
Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars
it's funny... I downloaded it two days ago and I am sure it was in open access!

[Julius]

here it is:
Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars
it's funny... I downloaded it two days ago and I am sure it was in open access!

Thanks for your effort Paolo but I still don't have access to it for some reason.

[atomoid]

Oops! I completely misread the coordinates of the granitoid exposures in Syrtis Major. The correct description of the location is that there are two exposures contained within a single area that is bounded by a line running from 61.8 to 65.9 degrees East longitude and a line running from 18.4 to 20.5 degrees North latitude. By the way, the total area of exposures with significant concentrations is 19 square kilometers.

Sorry for the screw up.

curious to see if the granite would be positioned relative to Mars' magnetic features perhaps suggesting such subduction zones were positioned according to plate spreading as indicated by remnant fields..? but if i'm reading the coordinates correctly thats around Isidis..

[Julius]

Impressive study providing detailed analysis of different rock stratigraphy along the curiosity traverse from Bradbury to Murray formation. However there is no mention of rock compostion along the way. As far as I know, there had been a puzzle as the rock make up up to now had been largely basaltic in nature. Provided that these sediments had been theorised as being laid down by water, this basaltic composition seems somewhat of a contradiction since water should have altered the basaltic nature of the rock. Any thoughts?

[elakdawalla]

You can download the recent Science paper from the MSL website: http://mars.nasa.gov/msl/mission/science/researchpapers/

[serpens]

curious to see if the granite would be positioned relative to Mars' magnetic features perhaps suggesting such subduction zones were positioned according to plate spreading as indicated by remnant fields..? but if i'm reading the coordinates correctly thats around Isidis..

Impacts can demagnetise any rock having a residual field so the identification of granite near a massive impact feature with little remnant magnetism is not a contradiction. Valles Marineris seems to show evidence of lateral movement which could imply plate tectonics, while the Tharsis Montes could be an ambulatory product similar to the Hawaiian chain. As far as Gale Crater is concerned, Sautter et al (Nature Geoscience 8, 605–609 (2015)) drew attention to the possible correlation between the feldspar-rich light coloured magmatic rocks found by Curiosity and continental crust. Given the extent of cratering the wonder is that any remnants of Mar's magnetic field survived.