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Green Mineral Indicates Mars Is Dry



 
 
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  #1  
Old October 24th 03, 01:37 AM
Ron Baalke
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Default Green Mineral Indicates Mars Is Dry


Contact: Heidi Koontz

303-202-4763
United States Geological Survey

Green mineral indicates red planet is dry

The presence of a common green mineral on Mars suggests that the red planet
could have been cold and dry since the mineral has been exposed, which may
be more than a billion years according to new research appearing in the Oct.
24 edition of Science.

Todd Hoefen, a U.S. Geological Survey (USGS) geophysicist, led a team of
researchers from USGS, Arizona State University and NASA, that found
abundant quantities of olivine on Mars. They based their conclusions on data
obtained from a Thermal Emission Spectrometer (TES) carried by the Mars
Global Surveyor (MGS).

Olivine, a transparent green-colored mineral found in many mafic rocks, is
susceptible to chemical weathering and readily alters to other minerals such
as iddingsite, goethite, serpentine, chlorite, smectite, maghemite and
hematite in the presence of water. Except for trace amounts of hematite,
which gives Mars its red color, none of these other weathering products have
been found.

The team detected a 30,000 square kilometer area rich in olivine, in the
Nili Fossae region of Mars. Nili Fossae has been interpreted as a complex of
grabens and fractures related to the formation of the Isidis impact basin,
where post-impact faulting exposed the abundant olivine. They have also
found smaller deposits of olivine all over the planet, all indicating a
surface dominated by volcanic processes.

The fact that so much olivine is exposed at the surface indicates that there
has been little to no weathering due to water, thus no liquid water-mineral
chemical reactions. The age of the surface is somewhat uncertain but is
probably over 3 billion years old.

It took approximately three years for the MGS spacecraft and the TES
instrument to gather the data for the analysis, and scientists another year
to analyze the results. The MGS spacecraft is healthy and continues to map
Mars.

###

The USGS serves the nation by providing reliable scientific information to
describe and understand the Earth; minimize loss of life and property from
natural disasters; manage water, biological, energy, and mineral resources;
and enhance and protect our quality of life.
  #2  
Old October 24th 03, 07:16 PM
Robert Clark
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Posts: n/a
Default Green Mineral Indicates Mars Is Dry

This area is only 30,000 sq. kilometers or comparable to an area of
300km by 100km.
Saying Mars is dry on the basis of this is like saying Earth is dry
on the basis of the Sahara desert.

An earlier report measuring olivine over large parts of Mars found
olivine on 1 million square miles:

New Evidence Suggests Cold, Dry Mars
posted: 07:18 am ET
02 November 2000
http://www.space.com/scienceastronom...ry_001101.html

This report also claimed Mars has always been dry on this basis. The
problem is that Mars with a diameter of about 4000 miles means 1
million square miles corresponds to about 2% of the Martian surface,
using the formula for surface area for a sphere 4*Pi*radius^2 and 2000
miles for the radius.
But Earth itself has desert areas that account for 20% of its land
area, and even when you account for the fact that the Earth is covered
by 70% water, that means deserts on Earth account for 6% of its total
surface area:

Desert Habitats
Deserts of the World
"Deserts cover about one fifth (20 percent) of the earth's land area.
The desert is a harsh environment with very little rainfall and
extreme temperatures. "
http://www.enchantedlearning.com/bio...t/desert.shtml

So saying saying Mars is dry by looking at the portion that contained
olivine ignoring the overwheling majority that did not is like looking
at only the desert areas on Earth and concluding that it is dry, and
ignoring the wet areas.


Bob Clark


(Ron Baalke) wrote in message ...
Contact: Heidi Koontz

303-202-4763
United States Geological Survey

Green mineral indicates red planet is dry

The presence of a common green mineral on Mars suggests that the red planet
could have been cold and dry since the mineral has been exposed, which may
be more than a billion years according to new research appearing in the Oct.
24 edition of Science.

Todd Hoefen, a U.S. Geological Survey (USGS) geophysicist, led a team of
researchers from USGS, Arizona State University and NASA, that found
abundant quantities of olivine on Mars. They based their conclusions on data
obtained from a Thermal Emission Spectrometer (TES) carried by the Mars
Global Surveyor (MGS).

Olivine, a transparent green-colored mineral found in many mafic rocks, is
susceptible to chemical weathering and readily alters to other minerals such
as iddingsite, goethite, serpentine, chlorite, smectite, maghemite and
hematite in the presence of water. Except for trace amounts of hematite,
which gives Mars its red color, none of these other weathering products have
been found.

The team detected a 30,000 square kilometer area rich in olivine, in the
Nili Fossae region of Mars. Nili Fossae has been interpreted as a complex of
grabens and fractures related to the formation of the Isidis impact basin,
where post-impact faulting exposed the abundant olivine. They have also
found smaller deposits of olivine all over the planet, all indicating a
surface dominated by volcanic processes.

The fact that so much olivine is exposed at the surface indicates that there
has been little to no weathering due to water, thus no liquid water-mineral
chemical reactions. The age of the surface is somewhat uncertain but is
probably over 3 billion years old.

It took approximately three years for the MGS spacecraft and the TES
instrument to gather the data for the analysis, and scientists another year
to analyze the results. The MGS spacecraft is healthy and continues to map
Mars.

###

The USGS serves the nation by providing reliable scientific information to
describe and understand the Earth; minimize loss of life and property from
natural disasters; manage water, biological, energy, and mineral resources;
and enhance and protect our quality of life.

  #3  
Old October 24th 03, 10:10 PM
Robert Casey
external usenet poster
 
Posts: n/a
Default Green Mineral Indicates Mars Is Dry

Ron Baalke wrote:

Green mineral indicates red planet is dry



Just like Utah? Where can someone get a beer around here?

:-)

  #4  
Old October 25th 03, 03:13 AM
Marc 182
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Posts: n/a
Default Green Mineral Indicates Mars Is Dry

In article ,
says...
This area is only 30,000 sq. kilometers or comparable to an area of
300km by 100km.
Saying Mars is dry on the basis of this is like saying Earth is dry
on the basis of the Sahara desert.

An earlier report measuring olivine over large parts of Mars found
olivine on 1 million square miles:

New Evidence Suggests Cold, Dry Mars
posted: 07:18 am ET
02 November 2000
http://www.space.com/scienceastronom...ry_001101.html

This report also claimed Mars has always been dry on this basis. The
problem is that Mars with a diameter of about 4000 miles means 1
million square miles corresponds to about 2% of the Martian surface,
using the formula for surface area for a sphere 4*Pi*radius^2 and 2000
miles for the radius.
But Earth itself has desert areas that account for 20% of its land
area, and even when you account for the fact that the Earth is covered
by 70% water, that means deserts on Earth account for 6% of its total
surface area:

Desert Habitats
Deserts of the World
"Deserts cover about one fifth (20 percent) of the earth's land area.
The desert is a harsh environment with very little rainfall and
extreme temperatures. "
http://www.enchantedlearning.com/bio...t/desert.shtml

So saying saying Mars is dry by looking at the portion that contained
olivine ignoring the overwheling majority that did not is like looking
at only the desert areas on Earth and concluding that it is dry, and
ignoring the wet areas.


There is a green beach in Hawaii made of olivine. Not exactly dry
there! See:

http://www.sease.com/regina/hawaiibeaches.html#green

  #5  
Old October 25th 03, 05:40 AM
Henry Spencer
external usenet poster
 
Posts: n/a
Default Green Mineral Indicates Mars Is Dry

In article ,
Marc 182 wrote:
There is a green beach in Hawaii made of olivine. Not exactly dry
there!


The issue is not that olivine explodes in contact with water :-), but that
it's *relatively* reactive in the presence of water, and does not last
long *by geological time standards* in a wet environment. That Hawaiian
beach is geologically very young (as is everything on the Big Island).

There is also at least one greenish beach in the Galapagos, although the
green isn't as conspicuous. (Don't know if it's in the guidebooks, but a
good guide will point out the green grains in the sand.) Same story --
olivine eroded out of lava. And again, geologically very new.

So a big, old area of exposed olivine indicates that at least one part of
Mars has been quite dry for a long time.

See:
http://www.sease.com/regina/hawaiibeaches.html#green


The beach is actually sort of olive-drab, not bright green. (And it's not
a six-mile hike, unless you're figuring the round trip; it's about three.
Mind you, that's three miles out and then three back with no shade and no
water except what you brought with you, and it's hot...)
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |
  #6  
Old October 25th 03, 06:29 AM
george
external usenet poster
 
Posts: n/a
Default Green Mineral Indicates Mars Is Dry


"Marc 182" wrote in message
t...
In article ,
says...
This area is only 30,000 sq. kilometers or comparable to an area of
300km by 100km.
Saying Mars is dry on the basis of this is like saying Earth is dry
on the basis of the Sahara desert.

An earlier report measuring olivine over large parts of Mars found
olivine on 1 million square miles:

New Evidence Suggests Cold, Dry Mars
posted: 07:18 am ET
02 November 2000
http://www.space.com/scienceastronom...ry_001101.html

This report also claimed Mars has always been dry on this basis. The
problem is that Mars with a diameter of about 4000 miles means 1
million square miles corresponds to about 2% of the Martian surface,
using the formula for surface area for a sphere 4*Pi*radius^2 and 2000
miles for the radius.
But Earth itself has desert areas that account for 20% of its land
area, and even when you account for the fact that the Earth is covered
by 70% water, that means deserts on Earth account for 6% of its total
surface area:

Desert Habitats
Deserts of the World
"Deserts cover about one fifth (20 percent) of the earth's land area.
The desert is a harsh environment with very little rainfall and
extreme temperatures. "
http://www.enchantedlearning.com/bio...t/desert.shtml

So saying saying Mars is dry by looking at the portion that contained
olivine ignoring the overwheling majority that did not is like looking
at only the desert areas on Earth and concluding that it is dry, and
ignoring the wet areas.


There is a green beach in Hawaii made of olivine. Not exactly dry
there! See:

http://www.sease.com/regina/hawaiibeaches.html#green


The problem there is age. If the olivine on Mars is as old as they say it
is (billions of years), then, you wouldn't expect to find much olivine left
if chemical weathering had occurred. The beaches in Hawaii are much
younger, on the order of hundreds of thousands to a few million years, and
so are still relatively fresh..


  #7  
Old October 25th 03, 09:09 AM
Marc 182
external usenet poster
 
Posts: n/a
Default Green Mineral Indicates Mars Is Dry

In article , says...
In article ,
Marc 182 wrote:
There is a green beach in Hawaii made of olivine. Not exactly dry
there!


The issue is not that olivine explodes in contact with water :-), but that
it's *relatively* reactive in the presence of water, and does not last
long *by geological time standards* in a wet environment. That Hawaiian
beach is geologically very young (as is everything on the Big Island).


Yeah, I know. The reason I'm aware of that beach is because a geologist
coworker returned from his honeymoon waving a vial of green sand around.
When I failed to react with the proper shock and awe, the nature of
olivine was explained to me in detail... *sigh*.

There is also at least one greenish beach in the Galapagos, although the
green isn't as conspicuous. (Don't know if it's in the guidebooks, but a
good guide will point out the green grains in the sand.) Same story --
olivine eroded out of lava. And again, geologically very new.

So a big, old area of exposed olivine indicates that at least one part of
Mars has been quite dry for a long time.


I didn't really have a point to my post, just being a bit snide.
Following up on that theme, "the surface of Mars is dry, wow, never
would have expected that!"

I do wonder, could this large area of olivine be a dusting of powder
eroded by wind and sand from some local volcanic rock (a dusty analog to
that beach)? Actually, now that I think about it, the source wouldn't
have to be local. Over millennia winds could have selectively sorted out
olivine grains in that area.

Also, does the presence of olivine rule out permafrost, or other
sequestered water, right below it?

See:
http://www.sease.com/regina/hawaiibeaches.html#green

The beach is actually sort of olive-drab, not bright green. (And it's not
a six-mile hike, unless you're figuring the round trip; it's about three.
Mind you, that's three miles out and then three back with no shade and no
water except what you brought with you, and it's hot...)


The stuff I saw in that vial was rather pretty, maybe not emerald, but
not olive either. The difference between wet and dry sand maybe?

Marc
  #8  
Old October 25th 03, 11:46 AM
Robert Clark
external usenet poster
 
Posts: n/a
Default Green Mineral Indicates Mars Is Dry

"george" wrote in message . ..
"Marc 182" wrote in message
t...
In article ,
says...
This area is only 30,000 sq. kilometers or comparable to an area of
300km by 100km.
Saying Mars is dry on the basis of this is like saying Earth is dry
on the basis of the Sahara desert.

An earlier report measuring olivine over large parts of Mars found
olivine on 1 million square miles:

New Evidence Suggests Cold, Dry Mars
posted: 07:18 am ET
02 November 2000
http://www.space.com/scienceastronom...ry_001101.html

This report also claimed Mars has always been dry on this basis. The
problem is that Mars with a diameter of about 4000 miles means 1
million square miles corresponds to about 2% of the Martian surface,
using the formula for surface area for a sphere 4*Pi*radius^2 and 2000
miles for the radius.
But Earth itself has desert areas that account for 20% of its land
area, and even when you account for the fact that the Earth is covered
by 70% water, that means deserts on Earth account for 6% of its total
surface area:

Desert Habitats
Deserts of the World
"Deserts cover about one fifth (20 percent) of the earth's land area.
The desert is a harsh environment with very little rainfall and
extreme temperatures. "
http://www.enchantedlearning.com/bio...t/desert.shtml

So saying saying Mars is dry by looking at the portion that contained
olivine ignoring the overwheling majority that did not is like looking
at only the desert areas on Earth and concluding that it is dry, and
ignoring the wet areas.


There is a green beach in Hawaii made of olivine. Not exactly dry
there! See:

http://www.sease.com/regina/hawaiibeaches.html#green


The problem there is age. If the olivine on Mars is as old as they say it
is (billions of years), then, you wouldn't expect to find much olivine left
if chemical weathering had occurred. The beaches in Hawaii are much
younger, on the order of hundreds of thousands to a few million years, and
so are still relatively fresh..



Here's another way of presenting the same data:

"98% of Mars may have been wet recently".


Bob Clark
  #9  
Old October 25th 03, 12:52 PM
george
external usenet poster
 
Posts: n/a
Default Green Mineral Indicates Mars Is Dry


"Robert Clark" wrote in message
om...
"george" wrote in message

. ..
"Marc 182" wrote in message
t...
In article ,
says...
This area is only 30,000 sq. kilometers or comparable to an area of
300km by 100km.
Saying Mars is dry on the basis of this is like saying Earth is dry
on the basis of the Sahara desert.

An earlier report measuring olivine over large parts of Mars found
olivine on 1 million square miles:

New Evidence Suggests Cold, Dry Mars
posted: 07:18 am ET
02 November 2000

http://www.space.com/scienceastronom...ry_001101.html

This report also claimed Mars has always been dry on this basis.

The
problem is that Mars with a diameter of about 4000 miles means 1
million square miles corresponds to about 2% of the Martian surface,
using the formula for surface area for a sphere 4*Pi*radius^2 and

2000
miles for the radius.
But Earth itself has desert areas that account for 20% of its land
area, and even when you account for the fact that the Earth is

covered
by 70% water, that means deserts on Earth account for 6% of its

total
surface area:

Desert Habitats
Deserts of the World
"Deserts cover about one fifth (20 percent) of the earth's land

area.
The desert is a harsh environment with very little rainfall and
extreme temperatures. "
http://www.enchantedlearning.com/bio...t/desert.shtml

So saying saying Mars is dry by looking at the portion that

contained
olivine ignoring the overwheling majority that did not is like

looking
at only the desert areas on Earth and concluding that it is dry, and
ignoring the wet areas.

There is a green beach in Hawaii made of olivine. Not exactly dry
there! See:

http://www.sease.com/regina/hawaiibeaches.html#green


The problem there is age. If the olivine on Mars is as old as they say

it
is (billions of years), then, you wouldn't expect to find much olivine

left
if chemical weathering had occurred. The beaches in Hawaii are much
younger, on the order of hundreds of thousands to a few million years,

and
so are still relatively fresh..



Here's another way of presenting the same data:

"98% of Mars may have been wet recently".


Bob Clark


That also assumes that all of the olivine on mars that is going to be found
has been found. But I understand what you are saying. I think the evidence
overwhelming favors the fact that there is still H20 on Mars. The only
question for me is was it ever in the right form or abundance that could
have produced, or is currently producing life? I think that given what we
know today about Mars, the likelihood of that being the case is very good.
Will we ever find it? I think its going to be a hard search.


  #10  
Old October 25th 03, 06:29 PM
Henry Spencer
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Posts: n/a
Default Green Mineral Indicates Mars Is Dry

In article ,
Marc 182 wrote:
So a big, old area of exposed olivine indicates that at least one part of
Mars has been quite dry for a long time.


...I do wonder, could this large area of olivine be a dusting of powder
eroded by wind and sand from some local volcanic rock (a dusty analog to
that beach)?


I wouldn't expect it to stay confined to a local area; the Martian winds
seem to be quite effective, over long periods, at moving dust around.
But probably nothing short of a field geologist on the surface could
*completely* rule that out.

Also, does the presence of olivine rule out permafrost, or other
sequestered water, right below it?


Depends on how that water got there, I think, but it seems like it would
take careful contriving to make an explanation work over a large area.

The beach is actually sort of olive-drab, not bright green...


The stuff I saw in that vial was rather pretty, maybe not emerald, but
not olive either. The difference between wet and dry sand maybe?


I remember it as being olive-drab pretty much everywhere (you see some of
it on the ground well before you reach the beach itself). But we couldn't
stay long and I can't claim that we really surveyed the area thoroughly;
he may have found a particularly nice-looking vein to sample.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |
 




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