Strangers on Mars -meteorites (APOD 21 Jul 2006)

life · Post by **life** » Sat Jul 22, 2006 2:40 am

today's APOD has a reference to a martian meteor, and when I click on it it takes me to a page which poses the question: how do you find martian meteors on planet earth?

I don't really get the point of the answer. Reminds me of the old joke: where do you find elephants? A: You don't, they're so big no-one ever looses them.

the real question seems to me: A meteor which originated on Mars, how did it leave mars in the first place? It's final resting place on earth can be explained as a combination of gravity and circumstance, but - supersonic martian volcanoes - or what does it take to explain how it left mars?
Or is the real fact that it was created out of the same original cosmic soup as mars, but has always otherwise led an existence of its own, and never REALLY originated on mars?

Qev · Post by **Qev** » Sat Jul 22, 2006 5:24 am

Well, the reigning theory would be that Martian meteorites originate from material blasted from the surface of Mars during large-scale impact events, eg. asteroid or comet impacts.

harry · Post by **harry** » Sat Jul 22, 2006 7:10 am

Hello All

It is a possiblity that a large meteor eploded on Mars.

The question is

What part game to earth?

The Meteor part or the Mars part.

and if so,,,,,,,how do you prove it if they all havce the same origin within our solar system.

This is a good one for aichip

aichip · Post by **aichip** » Sat Jul 22, 2006 2:21 pm

There are a number of mechanism for getting a meteor of a planet the size of Mars. Most center around a large impact. In some cases, the impact might directly knock material into space, in others it might actually create a shock wave that can travel through the planet, where it is focused (almost like a lens) as it reaches the other side of the planet. Rock is then thrown off in a process called spalling.

Of course, it would take a huge impact, but in theory it is possible.

Now, how do they know if a meteorite is from Mars? First, the chemistry of a meteorite is a clue. We have a lot of information about what Mars is made of and we have found meteorites that match that chemistry. But that is only part of the story.

Next, they look for trapped bubbles of gas in the meteorite and test them to see if they match the Martian atmosphere's chemistry. If they do, then you have a good candidate for a meteorite from Mars.

Then the outside of the meteorite is checked for cosmic ray trails. This tells you how long it was in space. And, analysis of the isotopes can also be used to help confirm or refute the idea it is from Mars.

If the meteorite matches the chemistry, isotope ratios, atmospheric gas, and shows that it has been in space for a few million years, then it is almost certainly a Martian rock. After all, there are only a few terrestrial planets in our solar system, and that helps us a lot by narrowing things down.

harry · Post by **harry** » Sat Jul 22, 2006 2:46 pm

Hello All

Yep,,,,,,,,,,,,,,,that was one for aichip

DavidLeodis · Post by **DavidLeodis** » Sat Jul 22, 2006 6:53 pm

A little above and to the right of the large dark rock is a smaller somewhat rounded rock that appears to have a cross on it! That rock (it is seen better in the full sized image that is brought up through the "This view" link) seems to be composed of a light colour base and a darker top. It does seem to be an odd rock. The cross may be a strange erosional effect, as it does not seem to be shadow. Does anybody else think the rock looks odd (or even see what I see!).

toejam · Post by **toejam** » Sat Jul 22, 2006 8:35 pm

Yes. The cross is there, on the rock. Anyone explain it?

orin stepanek · Post by **orin stepanek** » Sun Jul 23, 2006 4:32 am

http://antwrp.gsfc.nasa.gov/apod/image/ ... orites.jpg
Yes I see the Cross shape also! And beneath that rack is a bigger rock; Under that rock is a chip that looks a bit like driftwood. Probably just an eroded rock.???

BMAONE23 · Post by **BMAONE23** » Sun Jul 23, 2006 10:52 pm

If you are refering to what I believe you to be refering to, the "Driftwood" resembles the "Dust Bunny" at Eagle Crater.

BMAONE23 · Post by **BMAONE23** » Sun Jul 23, 2006 10:58 pm

http://www.imagehosting.us/index.php?ac ... nt=1439453

Dust Bunny

http://www.imagehosting.us/index.php?ac ... nt=1439318

Driftwood???

orin stepanek · Post by **orin stepanek** » Mon Jul 24, 2006 4:35 am

Hey BMAONE23; I noticed that one also, but I meant the flat object under and to the right of the big black rock that is directly below the cross rock. I wish I had the equipment to copy or circle that portion of the print!
Orin

ckam · Post by **ckam** » Mon Jul 24, 2006 11:27 am

I believe I can help:

I used an equipment called MS® Paint™

ckam · Post by **ckam** » Mon Jul 24, 2006 11:32 am

and the cross, I believe, is remnants of old martian christian church, what else. this adds some fuel to a theory that god has played with red planet first.

aichip · Post by **aichip** » Mon Jul 24, 2006 12:25 pm

I retrieved the raw data from Sol 872 and assembled the image myself. NASA and Cornell always add that ruddy orange stuff all over them and kill the contrast and color in the process so you can't make heads or tails out of it.

Here is the calibration target, dusty but accurate.
http://xenotechresearch.com/s872cala.jpg

Now, I left the color correct but lightened the scene a little so you can tell a number of things right away.

http://xenotechresearch.com/s872clra.jpg

First, the rocks are not black, that is blue colored rock varnish identical to what is present in many of the other images. Second, the spur of rock sticking out fro under the larger porous rock is actually a thin layer of sedimentary rock, and if the spectra from these are any indication, it is identical to the bedrock in Meridiani and is therefore gypsum rock.

Third, the odd rock with the cross pattern is weathered gypsum also, and the cross pattern is no more than erosion creases in it. This stone is very soft and was probably cracked as it dried from mud into harder material. It should have the hardness of precipitated plaster.

Here is a resampled and sharpened close up view of the two rocks in question.

http://xenotechresearch.com/s872mag1.jpg

No real mysteries here, just a couple of sedimentary rocks that have weathered. They are interesting looking though.

BMAONE23 · Post by **BMAONE23** » Mon Jul 24, 2006 5:11 pm

OK,
I see waht you are talking about now. I believe that the "Driftwood" is a (large) flat rock seen edge on that the larger volcanic boulder is siting upon.
See following image
http://xenotechresearch.com/s872mag1.jpg

The Cross rock in intresting.

orin stepanek · Post by **orin stepanek** » Mon Jul 24, 2006 5:26 pm

Nice clips ckam and BMAONE23; that is the rock! I believe aichip is correct that it is sedimentary. But it is an interesting piece. That rock you depicted BMAONE23; is also interesting. The soil in this photo looks almost like a river bottom;

but maybe wind storms may have played a role in shaping the landscape as it is alongside a hill.
Orin

BMAONE23 · Post by **BMAONE23** » Mon Jul 24, 2006 7:18 pm

Looking at the distance to the "Cross Rock" I would estimate it to be about the size a Grave Headstone. hmmmm

ckam · Post by **ckam** » Tue Jul 25, 2006 7:51 am

and I wonder what is written on the back side?

orin stepanek · Post by **orin stepanek** » Tue Jul 25, 2006 4:31 pm

R.I.P.

Orin

BMAONE23 · Post by **BMAONE23** » Tue Jul 25, 2006 4:51 pm

How about

Here lies Marvin
He finally got away
from that wascally wabbit

Wadsworth · Post by **Wadsworth** » Thu Jul 27, 2006 6:24 pm

After downloading the high resolution tif image, sharpening and enhancing edges, here is what the 'cross' rock looks like.

And upon closer inspection, one can make out some ancient Martian hieroglyphics or perhaps simply a juvenile Martians attempt at outward expression through graffiti.

toejam · Post by **toejam** » Fri Jul 28, 2006 8:10 pm

And on the little rock in front of the cross are my real initials -- S A --. Don't remember too clearly carving them, but had a lot of Oaxacan mescal that night.

harry · Post by **harry** » Sun Jul 30, 2006 12:39 pm

Hello All

The cross is a normal erosion feature.

Starship Asterisk*

Strangers on Mars -meteorites (APOD 21 Jul 2006)

Strangers on Mars -meteorites (APOD 21 Jul 2006)

Martian meteorites

Strangers on Mars. (APOD 21 Jul 2006)

Odd rocks, better image to work with

cross rock