[meteorite-list] Pebbly Rocks Testify to Old Streambed on Mars (MSL)

From: Steve Dunklee <steve.dunklee_at_meteoritecentral.com>
Date: Sat, 1 Jun 2013 23:28:56 -0700 (PDT)
Message-ID: <1370154536.25991.YahooMailClassic_at_web122605.mail.ne1.yahoo.com>

Hmm heres another interesting possibility. The co2 frost covers a rock overnight then when daylight hits it thaws the co2 from the same direction repeatedly causing the pebbles to tumble a microscopic amount each day.
   It might take thousands of years for co2 to do the same kind of erosion water could do in a day. I know it takes heat for the gas to dissipate into the atmosphere so it would tend to stay thicker close to the surface like frost here in winter in low areas. Then as the martian winds whip up it would hit the denser gas near the surface and slosh it around and actually increase the pressure near the surface just like the storm surge of a hurricane.
     More time and more experiments will tell us what is happening. I would like to see more temperature , pressure and wind speed measurements done close to the surface in the streambeds and then out and above the stream beds.
     Some simulations of mars atmosphere recreated in a lab might help. Atmospheric pressures directly on top of solid co2 as it sublimates might actually exceed for a few mm, earths atmospheric pressures until it dissipates. It takes energy to dissipate the gas into the atmosphere . and its pretty cold on Mars.
Cheers
Steve
--- On Sat, 6/1/13, Pict <pict at pict.co.uk> wrote:

> From: Pict <pict at pict.co.uk>
> Subject: Re: [meteorite-list] Pebbly Rocks Testify to Old Streambed on Mars (MSL)
> To: "Meteorite-list at meteoritecentral.com" <meteorite-list at meteoritecentral.com>
> Date: Saturday, June 1, 2013, 4:59 PM
> Aeolian desert sands can exhibit
> remarkable sphericity, rounding and
> sorting not unlike extremely mature water worn clastic
> sediments, but I
> don't think the phenomena extends to grain sizes beyond a
> few millimetres.
> It does seem conceivable that very high wind speeds with a
> denser
> atmosphere might get tumbling agitation going with larger
> rocks, but
> poorly sorted conglomerates suggests water not wind from an
> earthly
> perspective.
> John
>
> On 01/06/2013 23:55, "Graham Ensor" <graham.ensor at gmail.com>
> wrote:
>
> >Yes, Steve, Larry....erosion, if the flowing CO2 could
> produce any,
> >would not be anything like flowing water...eg tumbling
> rock into round
> >pebbles..the best you could hope for would be some sorts
> of ventifacts
> >being created...just as flowing gases (wind) create on
> earth.
> >
> >Graham
> >
> >On Sat, Jun 1, 2013 at 1:14 PM,? <lebofsky at lpl.arizona.edu>
> wrote:
> >> Hi Steve:
> >>
> >> Yes, I did see your video link. Thanks for sending
> that. All that this
> >> demonstrates is that CO2 is denser than air and
> that, when it displaces
> >> the oxygen, the candle goes out. So, even in this
> case it is not the
> >>force
> >> of the CO2 that is putting the flame out, but the
> lack of oxygen.
> >>
> >> CO2 gas is 1.5 as dense as air, but 1/500 the
> density of water. I doubt
> >> that you could mimic the know effects of moving
> water in a stream bed
> >>with
> >> a much less dense gas. If nothing else, the gas
> would disperse in the
> >> atmosphere rapidly unlike the much denser water.
> >>
> >> Sublimation is a very slow process, look at comet
> nuclei. There is a
> >>limit
> >> to how fast something can sublimate. As the ice
> warms up and turns to
> >>gas,
> >> the energy needed to do this actually cools the
> surface (the same thing
> >>as
> >> evaporative cooling which cools you as sweat
> evaporates off of your
> >>skin).
> >> I wrote several papers years ago on ice
> sublimation.
> >>
> >> The scientists used the sizes and size distribution
> of the rounded
> >>grains
> >> to compare with what we see in stream beds on Earth
> and can actually
> >>come
> >> up with depth, duration, and speed of the water. I
> do not see how you
> >> could replicate that with a gentle flow of gas no
> matter how long you
> >>had.
> >>
> >> Your idea is interesting, but decades of research
> have shown that
> >>geologic
> >> processes on Mars (and other objects) are not that
> different than what
> >>we
> >> see on Earth. If we see on Mars what looks like a
> stream bed on Earth,
> >>it
> >> is likely that the process that formed the stream
> bed on Earth (water)
> >> also did this on Mars. So, what conditions would
> have been necessary for
> >> the stream bed to have formed on Mars? A little
> more atmosphere and a
> >> little warmer!
> >>
> >> I hope that this helps.
> >>
> >> Larry
> >>
> >>
> >>
> >>
> >>> I believe? I did not describe properly
> what I was trying to say. The
> >>>video
> >>> link I sent clearly showed co2 gas being poured
> from a beaker. During
> >>>the
> >>> cold mars night a thin layer of co2 frost can
> form on a hillside. when
> >>> daylight returns and thaws the frost, the
> recently sublimated co2 being
> >>> colder than the surrounding atmosphere is going
> to flow down hill.
> >>> Millions of years of colder denser gas flowing
> down hill is going to
> >>>cause
> >>> erosion that simulates the flow of water.
> >>>? ???Mars has an 100
> thousand year polar freeze thaw cycle. When
> >>>billions
> >>> of tons of co2 sublimate from the poles its
> going to flow out from the
> >>> poles and cause erosion as it does so. Millions
> of years of this
> >>> repeated cycle of the colder gas flowing down
> hill is going to carve
> >>> what looks like river beds, canyons and lakes.
> all without any water
> >>> needed.
> >>> Cheers
> >>> Steve
> >>>
> >>> --- On Fri, 5/31/13, Graham Ensor <graham.ensor at gmail.com>
> wrote:
> >>>
> >>>> From: Graham Ensor <graham.ensor at gmail.com>
> >>>> Subject: Re: [meteorite-list] Pebbly Rocks
> Testify to Old Streambed on
> >>>> Mars (MSL)
> >>>> To: lebofsky at lpl.arizona.edu
> >>>> Cc: "Steve Dunklee" <steve.dunklee at yahoo.com>,
> "Meteorite Mailing
> >>>>List"
> >>>> <meteorite-list at meteoritecentral.com>,
> "Ron Baalke"
> >>>> <baalke at zagami.jpl.nasa.gov>
> >>>> Date: Friday, May 31, 2013, 11:39 PM
> >>>> Hi Larry, that's exactly the word I
> >>>> was trying to look
> >>>> for..."sublimates"...just could not bring
> it to mind. (any
> >>>> was being
> >>>> too lazy to look it up)? So my
> thoughts were
> >>>> right....very unlikely
> >>>> for there ever to be any liquid CO2 on
> Mars.
> >>>>
> >>>> G
> >>>>
> >>>> On Fri, May 31, 2013 at 6:32 PM,?
> <lebofsky at lpl.arizona.edu>
> >>>> wrote:
> >>>> > Hi Graham and Steve:
> >>>> >
> >>>> > Technically, you are wrong--CO2
> sublimates (turns from
> >>>> solid to gas) and
> >>>> > does not evaporate (turns from liquid
> to gas). The
> >>>> triple point (where
> >>>> > solid, liquid, and gas exist)of CO2 is
> 5.1 atmospheres.
> >>>> Since the "sea
> >>>> > level" pressure on Mars is about 0.006
> atmospheres, the
> >>>> atmospheric
> >>>> > pressure on Mars would have had to
> have been 1000 times
> >>>> greater than it is
> >>>> > now. Not very likely. To have liquid
> water (enough for
> >>>> flowing rivers) the
> >>>> > pressure would have to be about 0.006
> atmospheres at 0
> >>>> degrees C. In fact,
> >>>> > I think that this is how they
> originally defined the
> >>>> mean surface of Mars.
> >>>> > The only problem is that Mars is
> generally too cold at
> >>>> this pressure for
> >>>> > there to be liquid water, so you would
> need a warmer
> >>>> Mars (by a about 60
> >>>> > degrees centigrade for the "average"
> temperature) in
> >>>> order to get water
> >>>> > flowing on Mars. This is much more
> likely than a
> >>>> 1000-fold increase in
> >>>> > surface pressure.
> >>>> >
> >>>> > In fact, there is evidence for liquid
> water on Mars,
> >>>> but not in great
> >>>> > amounts (gullies, for example).
> >>>> >
> >>>> > Larry
> >>>> >
> >>>> >> Hi Steve,
> >>>> >>
> >>>> >> Liquid CO2 cannot exsist as a
> liquid at atmospheric
> >>>> pressure. It must
> >>>> >> be pressurized above 60.4 psi to
> remain as a
> >>>> liquid....so would it
> >>>> >> have ever flowed on Mars at all?
> Solid CO2
> >>>> evaporates to gas on Earth
> >>>> >> and I would say it does the same
> on
> >>>> Mars....somebody correct me there
> >>>> >> if I am wrong?
> >>>> >>
> >>>> >> Interesting thought about bog
> iron.....we would
> >>>> have hopes on Mars
> >>>> >> which would be the reverse of our
> hopes on Earth.
> >>>> Many pieces of bog
> >>>> >> iron have got folks excited on
> Earth because they
> >>>> were thought to be
> >>>> >> meteorites but are meteorwrongs.
> On Mars we would
> >>>> be hoping that a
> >>>> >> meteorite was bog iron as that
> would indicate a bog
> >>>> and thus peat and
> >>>> >> plantlife. As far as I know bog
> iron is associated
> >>>> with pea bogs and
> >>>> >> cannot form just with water...now
> a layer of old
> >>>> peat bog/coal would
> >>>> >> be an exciting find on Mars.
> >>>> >>
> >>>> >> Graham
> >>>> >>
> >>>> >> On Fri, May 31, 2013 at 9:41 AM,
> Steve Dunklee
> >>>> <steve.dunklee at yahoo.com>
> >>>> >> wrote:
> >>>> >>> What is the composition of the
> pebbles? and
> >>>> other deposits? if there are
> >>>> >>> not carbonates or other water
> soluable
> >>>> constiuentes then we may have to
> >>>> >>> accept the flow of carbon
> dioxide as the cause
> >>>> of the water like erosion
> >>>> >>> caused by the heating and
> cooling? on
> >>>> mars. where is the bog iron and
> >>>> >>> limestone or other
> precipitates which would be
> >>>> formed by water? As much
> >>>> >>> as I would wish for life and
> water on mars I
> >>>> see nothing to convince me
> >>>> >>> yet.
> >>>> >>> Cheers
> >>>> >>> Steve Dunklee
> >>>> >>> --- On Thu, 5/30/13, Ron
> Baalke <baalke at zagami.jpl.nasa.gov>
> >>>> wrote:
> >>>> >>>
> >>>> >>>> From: Ron Baalke <baalke at zagami.jpl.nasa.gov>
> >>>> >>>> Subject: [meteorite-list]
> Pebbly Rocks
> >>>> Testify to Old Streambed on Mars
> >>>> >>>> (MSL)
> >>>> >>>> To: "Meteorite Mailing
> List"
> >>>><meteorite-list at meteoritecentral.com>
> >>>> >>>> Date: Thursday, May 30,
> 2013, 7:01 PM
> >>>> >>>>
> >>>> >>>> http://www.jpl.nasa.gov/news/news.php?release=2013-181
> >>>> >>>>
> >>>> >>>>
> >>>> >>>> Pebbly Rocks Testify to
> Old Streambed on
> >>>> Mars
> >>>> >>>> Jet Propulsion Laboratory
> >>>> >>>> May 30, 2013
> >>>> >>>>
> >>>> >>>> PASADENA, Calif. -
> Detailed analysis and
> >>>> review have borne
> >>>> >>>> out
> >>>> >>>> researchers' initial
> interpretation of
> >>>> pebble-containing
> >>>> >>>> slabs that
> >>>> >>>> NASA's Mars rover
> Curiosity investigated
> >>>> last year: They are
> >>>> >>>> part of an
> >>>> >>>> ancient streambed.
> >>>> >>>>
> >>>> >>>> The rocks are the first
> ever found on Mars
> >>>> that contain
> >>>> >>>> streambed
> >>>> >>>> gravels. The sizes and
> shapes of the
> >>>> gravels embedded in
> >>>> >>>> these
> >>>> >>>> conglomerate rocks -- from
> the size of sand
> >>>> particles to the
> >>>> >>>> size of
> >>>> >>>> golf balls -- enabled
> researchers to
> >>>> calculate the depth and
> >>>> >>>> speed of
> >>>> >>>> the water that once flowed
> at this
> >>>> location.
> >>>> >>>>
> >>>> >>>> "We completed more
> rigorous quantification
> >>>> of the outcrops
> >>>> >>>> to
> >>>> >>>> characterize the size
> distribution and
> >>>> roundness of the
> >>>> >>>> pebbles and sand
> >>>> >>>> that make up these
> conglomerates," said
> >>>> Rebecca Williams of
> >>>> >>>> the
> >>>> >>>> Planetary Science
> Institute, Tucson, Ariz.,
> >>>> lead author of a
> >>>> >>>> report
> >>>> >>>> about them in the journal
> Science this
> >>>> week. "We ended up
> >>>> >>>> with a
> >>>> >>>> calculation in the same
> range as our
> >>>> initial estimate last
> >>>> >>>> fall. At a
> >>>> >>>> minimum, the stream was
> flowing at a speed
> >>>> equivalent to a
> >>>> >>>> walking pace
> >>>> >>>> -- a meter, or three feet,
> per second --
> >>>> and it was
> >>>> >>>> ankle-deep to
> >>>> >>>> hip-deep."
> >>>> >>>>
> >>>> >>>> Three pavement-like rocks
> examined with the
> >>>> telephoto
> >>>> >>>> capability of
> >>>> >>>> Curiosity's Mast Camera
> (Mastcam) during
> >>>> the rover's first
> >>>> >>>> 40 days on
> >>>> >>>> Mars are the basis for the
> new report. One,
> >>>> "Goulburn," is
> >>>> >>>> immediately
> >>>> >>>> adjacent to the rover's
> "Bradbury Landing"
> >>>> touchdown site.
> >>>> >>>> The other
> >>>> >>>> two, "Link" and "Hottah,"
> are about 165 and
> >>>> 330 feet (50 and
> >>>> >>>> 100 meters)
> >>>> >>>> to the southeast.
> Researchers also used the
> >>>> rover's
> >>>> >>>> laser-shooting
> >>>> >>>> Chemistry and Camera
> (ChemCam) instrument
> >>>> to investigate the
> >>>> >>>> Link rock.
> >>>> >>>>
> >>>> >>>> "These conglomerates look
> amazingly like
> >>>> streambed deposits
> >>>> >>>> on Earth,"
> >>>> >>>> Williams said. "Most
> people are familiar
> >>>> with rounded river
> >>>> >>>> pebbles.
> >>>> >>>> Maybe you've picked up a
> smoothed, round
> >>>> rock to skip across
> >>>> >>>> the water.
> >>>> >>>> Seeing something so
> familiar on another
> >>>> world is exciting
> >>>> >>>> and also
> >>>> >>>> gratifying."
> >>>> >>>>
> >>>> >>>> The larger pebbles are not
> distributed
> >>>> evenly in the
> >>>> >>>> conglomerate rocks.
> >>>> >>>> In Hottah, researchers
> detected alternating
> >>>> pebble-rich
> >>>> >>>> layers and sand
> >>>> >>>> layers. This is common in
> streambed
> >>>> deposits on Earth and
> >>>> >>>> provides
> >>>> >>>> additional evidence for
> stream flow on
> >>>> Mars. In addition,
> >>>> >>>> many of the
> >>>> >>>> pebbles are touching each
> other, a sign
> >>>> that they rolled
> >>>> >>>> along the bed
> >>>> >>>> of a stream.
> >>>> >>>>
> >>>> >>>> "Our analysis of the
> amount of rounding of
> >>>> the pebbles
> >>>> >>>> provided further
> >>>> >>>> information," said Sanjeev
> Gupta of
> >>>> Imperial College,
> >>>> >>>> London, a
> >>>> >>>> co-author of the new
> report. "The rounding
> >>>> indicates
> >>>> >>>> sustained flow. It
> >>>> >>>> occurs as pebbles hit each
> other multiple
> >>>> times. This wasn't
> >>>> >>>> a one-off
> >>>> >>>> flow. It was sustained,
> certainly more than
> >>>> weeks or months,
> >>>> >>>> though we
> >>>> >>>> can't say exactly how
> long."
> >>>> >>>>
> >>>> >>>> The stream carried the
> gravels at least a
> >>>> few miles, or
> >>>> >>>> kilometers, the
> >>>> >>>> researchers estimated.
> >>>> >>>>
> >>>> >>>> The atmosphere of modern
> Mars is too thin
> >>>> to make a
> >>>> >>>> sustained stream
> >>>> >>>> flow of water possible,
> though the planet
> >>>> holds large
> >>>> >>>> quantities of
> >>>> >>>> water ice. Several types
> of evidence have
> >>>> indicated that
> >>>> >>>> ancient Mars
> >>>> >>>> had diverse environments
> with liquid water.
> >>>> However, none
> >>>> >>>> but these
> >>>> >>>> rocks found by Curiosity
> could provide the
> >>>> type of stream
> >>>> >>>> flow
> >>>> >>>> information published this
> week.
> >>>> Curiosity's images of
> >>>> >>>> conglomerate
> >>>> >>>> rocks indicate that
> atmospheric conditions
> >>>> at Gale Crater
> >>>> >>>> once enabled
> >>>> >>>> the flow of liquid water
> on the Martian
> >>>> surface.
> >>>> >>>>
> >>>> >>>> During a two-year prime
> mission,
> >>>> researchers are using
> >>>> >>>> Curiosity's 10
> >>>> >>>> science instruments to
> assess the
> >>>> environmental history in
> >>>> >>>> Gale Crater
> >>>> >>>> on Mars, where the rover
> has found evidence
> >>>> of ancient
> >>>> >>>> environmental
> >>>> >>>> conditions favorable for
> microbial life.
> >>>> >>>>
> >>>> >>>> More information about
> Curiosity is online
> >>>> at:
> >>>> >>>> http://www.jpl.nasa.gov/msl , http://www.nasa.gov/msl and
> >>>> >>>> http://mars.jpl.nasa.gov/msl/ .
> >>>> >>>>
> >>>> >>>> You can follow the mission
> on Facebook at:
> >>>> >>>> http://www.facebook.com/marscuriosity and
> >>>> >>>> on Twitter at
> >>>> >>>> http://www.twitter.com/marscuriosity .
> >>>> >>>>
> >>>> >>>> Guy Webster 818-354-6278
> >>>> >>>> Jet Propulsion Laboratory,
> Pasadena,
> >>>> Calif.
> >>>> >>>> guy.webster at jpl.nasa.gov
> >>>> >>>>
> >>>> >>>> 2013-181
> >>>> >>>>
> >>>> >>>>
> >>>>
> ______________________________________________
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Received on Sun 02 Jun 2013 02:28:56 AM PDT