Exhumed rocks reveal Mars water ran deep

Jun 28, 2012
The large 25 km-diameter crater in the foreground of this High Resolution Stereo Camera (HRSC) perspective view has excavated rocks which have been altered by groundwater in the crust before the impact occurred. Using OMEGA (Visible and Infrared Mineralogical Mapping Spectrometer) on ESA’s Mars Express and CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) on NASA’s Mars Reconnaissance Orbiter (MRO), scientists have identified hydrated minerals in the central mound of the crater, on the crater walls and on the large ejecta blanket around the crater. Hydrated minerals were found in 175 locations associated with other nearby craters in the Tyrrhena Terra region of Mars. Credits: Mars Express HRSC, ESA/DLR/FU Berlin (G. Neukum); NASA/MOLA Science Team; D. Loizeau et al.

(Phys.org) -- By studying rocks blasted out of impact craters, ESA’s Mars Express has found evidence that underground water persisted at depth for prolonged periods during the first billion years of the Red Planet’s existence.

Impact craters are natural windows into the history of planetary surfaces – the deeper the crater, the further back in time you can probe.

In addition, rocks blasted out during the impact offer a chance to study material that once lay hidden beneath the surface.

In a new study, ESA’s Express and NASA’s Mars Reconnaissance Orbiter zoomed in on craters in a 1000 x 2000 km region of the ancient southern highlands, called Tyrrhena Terra, to learn more about the history of water in this region.

Focusing on the chemistry of rocks embedded in the crater walls, rims and central uplifts, as well as the surrounding exhumed material, scientists identified 175 sites bearing minerals formed in the presence of water.  

“The large range of crater sizes studied, from less than 1 km to 84 km wide, indicates that these hydrated silicates were excavated from depths of tens of metres to kilometres,” says Damien Loizeau, lead author of the study.

“The composition of the rocks is such that underground water must have been present here for a long period of time in order to have altered their chemistry.”

The 1000 x 2000 km area region of Tyrrhena Terra (outlined by the white box in the inset) sits between two regions of low altitude - Hellas Planitia and Isidis Planitia - in Mars’ southern hemisphere, as shown in this global topography map. Hydrated minerals were found in 175 locations associated with impact craters in Tyrrhena Terra, such as inside the walls of craters, along crater rims, or in material excavated by the impact. Analysis suggests that these minerals were formed in the presence of water that persisted at depth for an extended period of time. Credits: NASA/MOLA Science Team /D. Loizeau et al.

While the material excavated by impacts appears to have been in close contact with water, there is little evidence for rocks on the surface lying between the craters in Tyrrhena Terra having been altered by water.

“Water circulation occurred several kilometres deep in the crust some 3.7 billion years ago, before the majority of craters formed in this region,” says co-author Nicolas Mangold.

“The water generated a diverse range of chemical changes in the rocks that reflect low temperatures near the surface to high temperatures at depth, but without a direct relationship to the surface conditions at that time.”

By comparison, Mawrth Vallis, one of the largest identified clay-rich regions of Mars, displays a more uniform aqueous mineralogy that indicates a closer link with surface processes.

“The role of liquid on Mars is of great importance for its habitability and this study using Mars Express describes a very large zone where groundwater was present for a long time,” says Olivier Witasse, ESA’s project scientist.

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kevinrtrs
1.1 / 5 (14) Jun 28, 2012
"Water circulation occurred several kilometres deep in the crust some 3.7 billion years ago, before the majority of craters formed in this region, says co-author Nicolas Mangold.

How does the author know this was the case? How does he get to the estimate of 3.7 billion years; based on what assumptions?
Surely no one was there to witness or record this presence of water, so how can he be sure it wasn't 100million years ago, or 10k years ago for that matter?

But of greater importance is - where did the water come from in the first place?
If one goes by the usual accretion model for planetary formation, the planet could not have had any water at that stage.
So just where did the water come from and how did it manage to STAY on Mars long enough to influence the rocks in this way?
Furthermore, where did it go?
chasehusky
5 / 5 (8) Jun 28, 2012
So just where did the water come from?


Mars likely acquired water over time from comets and carbonaceous asteroid impacts during the period of heavy bombardment. (see: C. F. Chyba, "Impact delivery and erosion of planetary oceans in the early inner solar system", Nature, 343, 129-133, 1990; and M. Kuppers, et al., "A large dust/ice ratio in the nucleus of comet 9P/Tempel 1", Nature, 437, 987-990, 2005)

Furthermore, where did it go?


Water vapor was swept out into space by impact erosion, sputtering and solar winds. Any water that remains is predominantly in the form of ice. (see: V. W. Boynton, et al., "Distribution of hydrogen in the near surface of Mars: Evidence for subsurface ice deposits", Science, 297, 85-85, 2002; J.-P. Bibring, et al., "Perennial water ice identified in the south polar cap of Mars", Nature, 428, 627-630, 2004; and M. C. Malin, "Density of Marian north polar layer deposits: Implications for composition", Geophys. Res. Lett., 13, 444-447, 1986)
chasehusky
5 / 5 (10) Jun 28, 2012
How does the author know this was the case?


The existence of Al and Fe/Mg phyllosilicates on Mars indicates that liquid water was once present. (see: J.-P. Bibring, et al., "Global mineralogical and aqueous Mars history derived from OMEGA/Mars Express data", Science, 312, 400-404, 2006; J. F. Mustard, et al., "Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument", Nature, 454, 305-309, 2008)

Note that the presence of liquid water was during a time when Mars had a higher surface pressure. (see: D. A. Brain and B. M. Jakosky, "Atmospheric loss since the onset of the Martian geologic record: Combined roles of impact erosion and sputtering", J. Geophys. Res., 103, 22689-22694, 1998)

How does he get to the estimate of 3.7 billion years?


One can use various geological features evident from the MRO-HiRISE/MRO-CRISM imagery to date the event to the Noachian era.
deatopmg
4 / 5 (3) Jun 28, 2012
From a myriad of photographs, some showing a liquid present in depressions, some showing muddy tracks, some discolored, i.e. wet, soil in depressions, plus Phoenix ice evidence, it's obvious that a large portion of the original water is still there. Soil temperatures as high as 20 deg C have been reported and the reported pressure is high enough for liquid water to exist.

And it's not liquid CO2. Conditions are just way too far from those required for CO2 to be liquid.
PussyCat_Eyes
1 / 5 (2) Jun 28, 2012
@kevinrtrs -
Kevin...I know that you believe in God, so I will say this in a religion context so that you may understand.
If God truly exists, and I do have faith that He does, do you honestly believe the tall stories in the Jewish bible that God made good conditions for intelligent life to form and evolve on earth without doing the same for other planets in our solar system and other planets in the universe? ARE YOU SERIOUS?
Don't you understand that by saying such things as 6 or 7,000 ya everything was created, you are severely limiting God's creativity and abilities to do what he wants? You are second-guessing what He did and is doing to suit the religious dogma that you've been taught. Haven't you ever understood that God is THE ULTIMATE SCIENTIST because he has done these wonderful things AND provided the means for our existence so long ago? He also gave our species and others the chance to EVOLVE AND GROW AND IMPROVE even without His help. Accept it. You'll feel a lot better.
PussyCat_Eyes
1 / 5 (2) Jun 28, 2012
(contd)
There is a growing number of people who have the Faith who have come to understand the connection between God the Original Scientist and the origins of life. We have faith that first there was the Plan that would gather all the right ingredients to begin life as a single cell. It was protected and nurtured to allow it to evolve over billions of years. That may seem like too long a time to you, but in the COSMIC scheme of things, it's just about right. Water is a key ingredient because we are basically a bag of fluid inside our skin.
We and our physiology are not perfect, which indicates that God did not INTEND us to be perfect, otherwise we might live forever...and that would be a detriment to the process of evolution. That's why we are born and then we die, to give evolution a chance to perfect our species, such as it is. But we got intelligence and knowledge out of it, and we're still struggling with that.
Don't go crazy for religion...it's all manmade, not approved by God
PussyCat_Eyes
1 / 5 (2) Jun 28, 2012
So just where did the water come from?


Furthermore, where did it go?


Water vapor was swept out into space by impact erosion, sputtering and solar winds. Any water that remains is predominantly in the form of ice. (see: V. W. Boynton, et al., "Distribution of hydrogen in the near surface of Mars: Evidence for subsurface ice deposits", Science, 297, 85-85, 2002; J.-P. Bibring, et al., "Perennial water ice identified in the south polar cap of Mars", Nature, 428, 627-630, 2004; and M. C. Malin, "Density of Marian north polar layer deposits: Implications for composition", Geophys. Res. Lett., 13, 444-447,...... - chasehusky

http://phys.org/n...ars.html
Close enough encounter with bodies from a small galaxy. That's also one possibility.
TheGhostofOtto1923
2 / 5 (4) Jun 28, 2012
How does the author know this was the case? How does he get to the estimate of 3.7 billion years; based on what assumptions?
Surely no one was there to witness or record this presence of water, so how can he be sure it wasn't 100million years ago...?

But of greater importance is - where did the water come from in the first place?
Etc. So easy to ask questions but so hard to answer them eh? Depends a lot on whether you really want to know, or whether you think you already DO know, and are just trying to say so in an underhanded way.

Scientists know the answers to many of your questions. As I assume these answers would upset you, I must conclude that you are one of those people who doesnt really want to know what they are.

Too bad. Ignorance is bliss - a primary component of faith. Thats why it FEELS so good.
Kevin...I know that you believe in God, so I will say this in a religion context so that you may understand.
See? This one is drunk as a skunk. Snicker. Duh.
TheGhostofOtto1923
1 / 5 (4) Jun 28, 2012
If God truly exists, and I do have faith that He does, do you honestly believe the tall stories in the Jewish bible that God made good conditions for intelligent life...ARE YOU SERIOUS?
Well, now, according to you NO jew ANYWHERE believes in these things and it is their book so they should know.
We and our physiology are not perfect, which indicates that God did not INTEND us to be perfect, otherwise we might live forever...and that would be a detriment to the process of evolution.
Bwaaahaaahaaahahahahaaaa oh jeez I just soiled myself.
Torbjorn_Larsson_OM
1 / 5 (1) Jul 01, 2012
"Mars likely acquired water over time from comets and carbonaceous asteroid impacts during the period of heavy bombardment. (see: C. F. Chyba, "Impact delivery and erosion of planetary oceans in the early inner solar system", Nature, 343, 129-133, 1990; and M. Kuppers, et al., "A large dust/ice ratio in the nucleus of comet 9P/Tempel 1", Nature, 437, 987-990, 2005)"

Except that this was, arguably, just superseded by new observations.

Mars is as wet as Earth is as seen in Mars meteorite the same minerals relatively pristine as well as processed retaining it [ http://www.space....irs.html ]. Earth is now ~ 0.05 % water by mass while typical asteroid impactors, chondrites, are 15-20 % by mass.

The uniformity between planets, and the isotope ratios suggesting at most 10 % comet contribution, suggest that the terrestrials got their water at aggregation.
Torbjorn_Larsson_OM
1 / 5 (1) Jul 01, 2012
[cont.] This is what the above observations tests, very likely.

One mechanism is physisorption, which even in the tough environment of the aggregating solar nebula would permit the same water content by mass between the ice line and up close to the Sun. (Enough water at 500 K.)

Drake, M. J. (2005) Origin of water in the terrestrial planets, Meteoritics and Planetary Science 40 (4), 515-656.

This is of course excellent news for exoplanet habitability as we know it! Enough water for life most everywhere - but also for plate tectonics even in terrestrial runts such as Earth, not too much water to have continents.