Martian sands shift slowly but surely

[Sam Wormley]

Martian sands shift slowly but surely
http://physicsweb.org/articles/news/11/5/14/1

15 May 2007

Physicists may have solved a long-standing mystery about sand dunes
on Mars. The dunes looks as if they should have been created by the
action of wind, but the Martian atmosphere is so still and thin that
it was thought impossible for wind to have played a part. New
computer simulations suggest that the wind can indeed drive the sand
dunes on Mars -- it's just that the dunes are formed far more slowly
than back on Earth (Phys. Rev. Lett. 98 198001).

Astronomers have long been puzzled by the sand dunes on Mars, which
were first discovered in 1971. The dunes look very much like those on
Earth, which suggests they were created by the action of wind. The
problem is that the Martian atmosphere is so thin and still -- so how
could the wind have played a part?

Even more curious is the fact that successive missions to Mars have
not detected any change in the positions of the dunes, whereas the
dunes on Earth are shifting constantly. Some scientists have
therefore suggested that the dunes were created long ago, when the
Martian atmosphere could have been much denser than it is today.

Now, however, Eric Parteli at the University of Stuttgart and Hans
Hermann at the Swiss Federal Institute of Technology in Zürich reckon
the Martian dunes could indeed form and shift under the planet's
current atmospheric conditions. They have carried out a series of
computer simulations of the formation of two distinct types of dunes
seen on Mars -- arrowhead-shaped "barchan" dunes, which are formed
when the wind blows mainly in one direction, and elongated
"exotic" dunes that are formed when the wind alternates
between two directions (see figures).

Assuming that the sand was subject to just one 40-second gust of wind
every five years -- conditions experienced by Mars probes -- the
simulations suggested that the exotic dunes could have formed from
barchan dunes over a period of about 10,000 to 50,000 years. Parteli
told Physics Web that under the same conditions, it would take about
4000 years for a dune to shift by 1 m, which could explain why the
dunes have not appeared to move since they were first discovered.

According to Parteli, the key to modelling the dunes is a process
called "saltation", whereby a grain of sand is lifted by the wind,
and driven along above the sand until it falls back, creating a
splash of ejected grains. The ejected grains could then also be
picked up by the wind leading to a rapid multiplication of the amount
of sand that is being blown along.

Saltation has been successfully modelled for dunes on Earth using
parameters determined experimentally. But when Parteli and Herrmann
used the same parameters under Martian conditions, they found that
dunes would not form. Undeterred, they turned to research done nearly
30 years ago that established that the airborne grains should travel
10 times faster on Mars than on Earth thanks to the planet\u2019s
thinner atmosphere and lower gravity. As a result, each Martian grain
should eject about ten times more sand upon impact than does a grain
on Earth. Using these saltation parameters, Parteli and Herrmann were
able to reproduce both the barchan and exotic dunes.

According to Parteli, the simulations suggest that atmospheric
conditions on Mars have been relatively stable over the past 50,000
years and that the dunes are not necessarily evidence that the
Martian atmosphere had been more Earth-like in the past.

[G=EMC^2 Glazier]

Sam Mars never had a watery surface,nor any why near an Earth type
atmosphere. If you look at Mars Husband Hill and its shape,also the sand
rippled area around it you get a great picture 0f Mars surface..Boulders
scattered around it can show us a lot. Look it up in Google its a great
picture taken by the Mars explorer "Rover Spirit" Husband Hill is
high up and sand blasted over a long time. The boulders are fairly new
and have sharper edges. Bert

[Sam Wormley]

G=EMC^2 Glazier wrote:
> Sam Mars never had a watery surface, nor any why near an Earth type
> atmosphere.

What does the evidence say? What made all those river channels and
flood planes in photographs of the surface? Where did that hematite
come from? Sedimentary rock?

Mars Odyssey (reached Mars Oct. 24, 2001)
http://mars.jpl.nasa.gov/odyssey/
http://mars.jpl.nasa.gov/spotlight/odyssey-mission-success.html

Mars: Dead or Alive - Nova 50- min
http://www.pbs.org/wgbh/nova/mars/program.html
When things go wrong!

Mars Exploration Rover Mission (reached Mars Jan 4 & 25, 2004)
http://marsrovers.jpl.nasa.gov/home/index.html
http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?Spirit
http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?Opportunity
> http://www.sciencemag.org/cgi/content/summary/305/5685/793
> http://www.sciencemag.org/cgi/content/summary/306/5702/1697
http://marsrovers.jpl.nasa.gov/newsroom/pressreleases/20060124a.html

Mars Reconnaissance Orbiter (reached Mars Mar. 10, 2006)
http://mars.jpl.nasa.gov/mro/
http://mars.jpl.nasa.gov/mro/science/
http://mars.jpl.nasa.gov/mro/mission/sc_instru.html 30 cm

Martian Cracks Show Signs of Once-Flowing Water
http://sciencenow.sciencemag.org/cgi/content/full/2007/215/1
Password Required

[G=EMC^2 Glazier]

Sam Those same type makings of Mars river flows are also on our Moon
They were created by the flow of lava. Mars has lots of volcanoes Best
to keep in mind that Olympus Mons is the largest in the whole solar
system. Also that sand erodes the same way as water,and Mars has global
sand storms that can last for months. NASA cons the public by keep
mentioning water,and the rovers have drilled inside rock,and not one
molecule of H2O was found in a billion parts tested The sun's
inferred photons make sure water will be broken down, Bert

[Sam Wormley]

You are certainly ignorant about Mars, Herb... there's water water
everywhere, just not a drop to drink (so far).

Light Deposits Indicate Water Flowing on Mars
http://antwrp.gsfc.nasa.gov/apod/ap061212.html
http://antwrp.gsfc.nasa.gov/apod/ap061231.html

Water Ice in a Martian Crater
http://antwrp.gsfc.nasa.gov/apod/ap050720.html

Neutron Mars
http://antwrp.gsfc.nasa.gov/apod/ap040904.html

Evidence that Mars was Wet
http://www.sciencemag.org/cgi/content/summary/305/5685/793
http://www.sciencemag.org/cgi/content/summary/306/5702/1697

[G=EMC^2 Glazier]

Sam Water Water every where,but not a molecule to be found. "Once upon
a time" Mars had oceans rivers lakes,and red clams. You Sam would find
only red clams not being reality. Truth is all of it is a fairy tail .It
is NASA giving the public a snow job. They know there is no money in
sand,and water is a lot more interesting and brings in the bucks. Sam
don't be so naive. Bert

[Sam Wormley]

OK, Herb.... hmmm sand... hmmm electronic chips.... hmmm!