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#1 2004-04-20 12:08:56

REB
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Re: Opportunity’s Journey - Opportunity's Trek across Mars

Bounce, a rock that Opportunity studied, was shown to be Basalt, which is different from those rocks in Eagle crater. I was initially surprised at these findings, since it looked like the rocks in Eagle crater.

It seems to me that the light native rock of this area of Mars weathers quickly, leaving behind the harder, darker, blueberries. I guess I should have not been surprised that bounce was not from this area, seeing that it has not weathered as quickly as the native rock.

Opportunity is now at a crater called Fram

See:
[http://marsrovers.jpl.nasa.gov/gallery/ … _n084.html]http://marsrovers.jpl.nasa.gov/gallery/ … _n084.html

Fram looks like it could be younger than Eagle crater. Its rocks do not appear to be nearly as eroded.


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#2 2004-04-20 17:27:20

atomoid
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Re: Opportunity’s Journey - Opportunity's Trek across Mars

In trying to come up with an explanation for Bounce, here's what I think is the most likely scenario: Bounce was gouged from far away hills by a glacier then carried and dropped off here by an iceberg eons ago, it was probably buried by some sediments and has since been exhumed by wind action. It will be interesting to see how many other basalt rocks are in the region.

The bedrock here is somewhat soft and erodes quickly. The fine light dust you see collected in places like the center of Fram crater as well as the lee side and other parts of of Eagle crater blows around easily and is generally removed from the area over time leaving everything else on the top of the soil. Heres a [http://www.lyle.org/mars/imagery/1M1330 … 1.JPG.html]closeup of this dust as seen at the [http://www.lyle.org/mars/imagery/1P1329 … 1.JPG.html]little ripple field in the [http://www.lyle.org/mars/imagery/1F1329 … 1.JPG.html]center of Eagle crater.

Underneath all the sand and blueberries, which have created an erosion-resistant cover for the soil and bedrock beneath, youll find this sedimentary bedrock going down at least a few hundred feet (if the appearance of other nearby craters form orbit is any guide). But if we do find that some of the craters punched deep enough to expose basaltic layers, then Bounce could be ejecta. Thats my impression anyway.


"I think it would be a good idea". - [url=http://www.quotationspage.com/quotes/Mahatma_Gandhi/]Mahatma Gandhi[/url], when asked what he thought of Western civilization.

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#3 2004-04-21 06:28:37

REB
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Re: Opportunity’s Journey - Opportunity's Trek across Mars

Antarctica and India meteorites linked to the same origins as Bounce. Bounce came from elsewhere on Mars than the region around Eagle Crater.

Check out the end of this press release;
[http://marsrovers.jpl.nasa.gov/gallery/ … 0414a.html]http://marsrovers.jpl.nasa.gov/gallery....4a.html

'Bounce' and Shergotty Share Common Ground

This illustration compares the light signature or spectrum of "Bounce," a rock at Meridiani Planum, to that of a martian meteorite found on Earth called Shergotty. Bounce's spectrum, and thus mineral composition, is unique to the rocks studies so far at Merdiani Planum and Gusev Crater, the landings sites of the Mars Exploration Rovers Opportunity and Spirit. However, the results here indicate that Bounce is not a one-of-a-kind rock, but shares origins with Shergotty. Shergotty landed in India in 1865. Bounce's spectra were taken on sol 67 by Opportunity's Moessbauer spectrometer.

And

Meteorite Linked to Rock at Meridiani

This meteorite, a basalt lava rock nearly indistinguishable from many Earth rocks, provided the first strong proof that meteorites could come from Mars. Originally weighing nearly 8 kilograms (17.6 pounds), it was collected in 1979 in the Elephant Moraine area of Antarctica. The side of the cube at the lower left in this image measures 1 centimeter (0.4 inches).

This picture shows a sawn face of this fine-grained gray rock. (The vertical stripes are saw marks.) The black patches in the rock are melted rock, or glass, formed when a large meteorite hit Mars near the rock. The meteorite impact probably threw this rock, dubbed "EETA79001," off Mars and toward Antarctica on Earth. The black glass contains traces of martian atmosphere gases.

The Mars Exploration Rover Opportunity has discovered that a rock dubbed "Bounce" at Meridiani Planum has a very similar mineral composition to this meteorite and likely shares common origins. Bounce itself is thought to have originated outside the area surrounding Opportunity's landing site; an impact or collision likely threw the rock away from its primary home.


"Run for it? Running's not a plan! Running's what you do, once a plan fails!"  -Earl Bassett

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#4 2004-04-21 10:38:31

rgcarnes
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Re: Opportunity’s Journey - Opportunity's Trek across Mars

Atomoid,

Do we know certainly that the white "dust" is not frost?


Rex G. Carnes

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#5 2004-04-21 13:35:32

REB
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Re: Opportunity’s Journey - Opportunity's Trek across Mars

Frost is possible, but I don't think it would last long during the day. It tends to quickly evaporate in the dry air. It could always form again the next night.

One of the Vikings observed frost on the surface.


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#6 2004-04-21 18:10:43

atomoid
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Re: Opportunity’s Journey - Opportunity's Trek across Mars

Frost is possible, but I don't think it would last long during the day. It tends to quickly evaporate in the dry air. It could always form again the next night.

One of the Vikings observed frost on the surface.

Here's the http://photojournal.jpl.nasa.gov/jpegMo … jpg]Viking ice. At the viking site, which was monitored by the lander for several years (plutonium power!) the frost appeared only in the winter. Even though the temperatures are low enough at Meridiani at night to support frost formation, maybe it has to do with weather patterns and humidity, so the jury is still out on when the rovers will see some frost if they last long enough. Also, the latitude at the Viking site was higher than at that at Meridiani so the seasonal variation was greater. Being summer at Meridiani, its less likely to be frost precipitated from the atmosphere, and if it came from under the ground there would surely be signs of water movement/slumpage/salt deposits associated with it. I used to think the white stuff was salt crusts left behind from evaporating water, but this doesnt fit the observations. The white stuff definately looks "wind-blown". From looking at http://www.lyle.org/mars/imagery/1M1330 … .html]this closeup of it, it pretty much looks like a talc-like very fine powdery dust, way too fine to see any individual motes. However, i still don't know what NASA says about it, last thing i heard, they said it was "same as the ubiquitous dust found everywhere on Mars", which sort of implies that they think it all blew in on the wind.

Im running with idea that its dust that has eroded from the local blueberry bedrock in Meridiani, just seems to be the simplest explanation while supporting all observations i am aware of so it just makes the most sense to me. im still waiting for a spectrometer analysis report that will definitively connect it to the bedorck but i havent heard anything (did i miss it?).


"I think it would be a good idea". - [url=http://www.quotationspage.com/quotes/Mahatma_Gandhi/]Mahatma Gandhi[/url], when asked what he thought of Western civilization.

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#7 2004-04-28 07:43:31

REB
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Re: Opportunity’s Journey - Opportunity's Trek across Mars

Atomoid, that is one of my favorite Viking pictures. (I have thought about going over the old Viking pictures and, with our new information from Spirit and Opportunity, seeing If I can find something overlooked all these years)

I think you are right about the 'white' stuff. THe bedrock around Eagle Crater seems to weather quickly, leaving the dark blueberrys.


"Run for it? Running's not a plan! Running's what you do, once a plan fails!"  -Earl Bassett

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