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Traveler
Pooh-Bah


Reged: 08/19/07

Loc: The Netherlands
Mars meteorites on Earth: how2 proof? new
      #5605241 - 01/04/13 05:23 PM

Hi all,

Read this story if you want: link.

How can man proof the meteorite is from Mars?


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Rick Woods
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Reged: 01/27/05

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Re: Mars meteorites on Earth: how2 proof? new [Re: Traveler]
      #5605371 - 01/04/13 06:53 PM

Mars meteorites have some unique properties. Most have been analyzed and determined to be basaltic lavas, formed within the last 1.3 billion years. This would require a non-terrestrial origin with active volcanoes in that time period, and the list of candidates is small. In addition, small bubbles of trapped gas in some specimens have been analyzed, and match the Martian atmosphere perfectly.

So, they're pretty sure the rocks are from Mars.


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llanitedave
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Reged: 09/26/05

Loc: Amargosa Valley, NV, USA
Re: Mars meteorites on Earth: how2 proof? new [Re: Traveler]
      #5605510 - 01/04/13 08:20 PM

Quote:


How can man proof the meteorite is from Mars?




You asked for "proof", and Rick gave you "evidence". They aren't the same thing, but proof is something you simply don't expect or get in science. We have compelling reasons to conclude that the meteorites are from Mars, and until/unless a better and contrary hypothesis becomes available, that's the conclusion we operate on.


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Rick Woods
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Re: Mars meteorites on Earth: how2 proof? new [Re: llanitedave]
      #5605843 - 01/05/13 12:34 AM

Quote:

Quote:


How can man proof the meteorite is from Mars?




You asked for "proof", and Rick gave you "evidence". They aren't the same thing, but proof is something you simply don't expect or get in science. We have compelling reasons to conclude that the meteorites are from Mars, and until/unless a better and contrary hypothesis becomes available, that's the conclusion we operate on.




You're absolutely right. My apologies for my sloppiness of expression.
I got carried away by the stength of the evidence; but it still isn't "proof".


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llanitedave
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Re: Mars meteorites on Earth: how2 proof? new [Re: Rick Woods]
      #5605921 - 01/05/13 01:47 AM

I didn't think it was sloppy, Rick. You didn't present it as anything other than what it was. I was just making an attempted independently "helpful" observation.

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Traveler
Pooh-Bah


Reged: 08/19/07

Loc: The Netherlands
Re: Mars meteorites on Earth: how2 proof? new [Re: llanitedave]
      #5606025 - 01/05/13 04:54 AM

But how did the material went from Mars? There has to be a gigantic explosion or collision needed. Is therefor any evidence?

Btw: the use of the word proof in stead of evidence has to do with the fact that English is not my native language. I ment evidence.


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PhilCo126
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Reged: 01/14/05

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Re: Mars meteorites on Earth: how2 proof? new [Re: Traveler]
      #5606035 - 01/05/13 05:14 AM

An impact on Mars could easily result to material being ejected as the red planet has a very low gravity. The planet can't even hold on to a decent atmosphere.
Every 780 days the planet Mars comes in opposition, the ideal position for interplanetary material transfer...
Remember the 1976 Viking I & Viking II experiments? Those learned us a lot on the Martian soil composition but a Sample Return mission would be far more interesting...


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Mister T
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Reged: 02/01/08

Loc: Upstate NY
Re: Mars meteorites on Earth: how2 proof? new [Re: Traveler]
      #5606151 - 01/05/13 09:05 AM

A Mars meteorite could have been ejected from Mars any time since Mars formed.

And could have remained in "orbit" for millions(billions) of years until it was perturbed so as to send it on a path to destiny with Earth.


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Qwickdraw
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Re: Mars meteorites on Earth: how2 proof? new [Re: Mister T]
      #5606207 - 01/05/13 09:41 AM

I have to wonder if the same process can cause a meteorite from Earth to land on Mars. Obviously the sun's gravity would have to first be overcome with enough inertia from a blast.

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llanitedave
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Re: Mars meteorites on Earth: how2 proof? new [Re: Qwickdraw]
      #5606387 - 01/05/13 11:31 AM

Blasting a rock from Earth to Mars would be much more difficult, since the Earth has three times the escape velocity. But it could happen, I suppose.

Interestingly enough, from the frame of reference of a solar orbit, the amount of energy change required to get from crossing Mars' orbit to one that crosses Earth's orbit is the same as going the other way. One requires a slowing down, and one requires a speeding up, but from an orbital mechanics standpoint, they're both equal.


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Rick Woods
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Re: Mars meteorites on Earth: how2 proof? new [Re: llanitedave]
      #5606751 - 01/05/13 02:44 PM

Quote:

Blasting a rock from Earth to Mars would be much more difficult, since the Earth has three times the escape velocity. But it could happen, I suppose.





That's also why, if life is found on Mars that is similar to that on Earth, there's a much better chance that we're them than that they're us (try saying that five times fast).


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dyslexic nam
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Re: Mars meteorites on Earth: how2 proof? new [Re: Rick Woods]
      #5609818 - 01/07/13 09:34 AM

One of the theories about the moon's formation is that a huge body collided with the earth and blew off a sizeable portion a few billion years ago. If this is true (and I think it is widely viewed as the most plausible explanation - though I am no expert), then an impact/explosion of that size would liekly have sent chunks of early-Earth in all sorts of directions, at velocities that could easilly escape our gravity. They may or may not have had the right trajectory to eventually land on Mars, but it is definitely plausible.

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llanitedave
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Re: Mars meteorites on Earth: how2 proof? new [Re: dyslexic nam]
      #5610028 - 01/07/13 11:33 AM

It's extremely plausible. But that was so long ago that I think it would be tough to find any traces of the debris, even on Mars. I'm also pretty confident that an impact of that magnitude would have obliterated any trace of life on either body, if it had even originated yet. (Although conceptually some traces might have remained on individual chunks that got blown off before they melted)

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Glassthrower
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Re: Mars meteorites on Earth: how2 proof? new [Re: llanitedave]
      #5613962 - 01/09/13 03:54 PM

For reference : http://www2.jpl.nasa.gov/snc/index.html

Generally speaking, for some Martian meteorites, scientists have analyzed microscopic pockets of trapped air inside the meteorite specimen. The components of this trapped air matched the composition of Martian atmosphere as measured by our rovers on Mars (Sojourner, etc).

There are other litmus tests we can use with meteorites now to look for suitable matches for a Martian origin. Oxygen-isotope testing will usually rule in/out certain planetary bodies as being the parent of a given meteorite type.

Cosmic-ray exposure data may also come into play, along with the usual electron microprobe, thin-sectioning, etc.

Scientists are becoming increasingly familiar with Martian and Lunar meteorites now, because improved recovery rates have flooded labs and institutions with readily-available specimens. Occasionally, an oddball will come along, like this new "Black Beauty" meteorite that is capturing media attention. Originally, it was classified as an "ungrouped achondrite" because it did not closely match any known meteorite type. Subsequent testing revealed it's true Martian origin.

It wasn't until the 20th century that we discovered Martian meteorites on Earth. Until then, museums and universities had some of these meteorites sitting in their geology departments, but nobody recognized their true origins then. (see Lafayette Martian meteorite, etc)

What makes this new Martian meteorite exciting is that it is the second-oldest known Martian meteorite to date. This is significant. Out of almost 50 known Martian meteorites, this new "Black Beauty" is the second oldest, next to ALH84001. The latter is famous for it's controversial "fossil bacteria" structures. Aside from these two meteorites, all of the other Martian meteorites have originated more recently from Mars - from the arid and cold Mars we still see today. Black Beauty is much older, and it represents a younger and much wetter Mars. Until now, scientists have not had access to a sample from this period in Martian history.

The last two years have been very exciting for planetary scientists. In 2011, we had the historic Tissint meteorite fall over Morocco that yielded the first pristine Martian sample to modern scientific instruments. And now we have this "Black Beauty" recovery, which is already being studied intensely by several scientists, including Dr. Carl Agee at the UNM Institute for Meteoritics.

Long after the media coverage fades away, this meteorite is going to yield it's secrets in papers and journals. It will be interesting to follow it through the research and see what emerges.

Talk about a one-two-three punch for new Martian data : Tissint, NWA 7034 (Black Beauty), and Curiosity!

Best regards and clear dark skies,

MikeG


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David Knisely
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Reged: 04/19/04

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Re: Mars meteorites on Earth: how2 proof? new [Re: Glassthrower]
      #5614133 - 01/09/13 05:29 PM

Glassthrower wrote:

Quote:

Generally speaking, for some Martian meteorites, scientists have analyzed microscopic pockets of trapped air inside the meteorite specimen. The components of this trapped air matched the composition of Martian atmosphere as measured by our rovers on Mars (Sojourner, etc).




Actually, Sojourner and the two MER rovers did not directly measure the atmospheric composition of the Martian atmosphere. Their main instruments (alpha particle X-ray spectrometer) were designed for study the composition of the rocks only. However, the atmospheric composition was measured by the Viking 1 and 2 landers in 1976 using the landers' Gas Chromatograph/Mass Spectrometer (GCMS), and these measurements were recently duplicated by similar instruments on the Curiosity rover. Clear skies to you.


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Traveler
Pooh-Bah


Reged: 08/19/07

Loc: The Netherlands
Re: Mars meteorites on Earth: how2 proof? new [Re: Glassthrower]
      #5614862 - 01/10/13 02:54 AM

Hi Michael,

Thanks a lot for the link and your in-depth writing. Much appreciated!

How do you see the possibility that some of the 50 meteorites aren't from Mars but are parts of the asteroidsbelt between Mars and Jupiter? These are the remaining of an old and destroyed planet, aren't they?


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Rick Woods
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Re: Mars meteorites on Earth: how2 proof? [Re: Traveler]
      #5615394 - 01/10/13 12:06 PM

The last I heard, the asteroids were considered planetesimals that were prevented from coagulating into a larger body by the gravity of Jupiter. (But, things may have changed since then?)

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