"How Scientists know if a Meteor is from Mars" Topic

Simple answer – They study the meteor and compare it to other meteors and/or rocks that come from or are on Mars, and if it is similar to those, then they say it's from Mars.

Now you can get very complicated in studying the meteor, some of it is going to be put under a microscope to see how the meteor looks, some is going to be burn 't to see what it's made of, some if it's doing very slow, very boring work determining the chemistry of the meteor, and then you compare it to data from Mar's probes, doing Spectral analysis of light coming from Mars (meaning that when light bounces off objects, the light is changed by the materials of the object, and you can use this to determine what the material the light bounced off of is made of), but what it really comes down to is comparing the measurements of the meteor you have with lots of other boring data from all the other objects you know of being from Mars , and rocks on Mars, and if it's similar, it's from Mars.

Yes, they could be wrong. But if it's similar to rocks from Mars and isn't from Mar's, then it's from a long, long, long away, another solar system, and since that's pretty unlikely, chances are, it's from Mars.

If it walks like a duck and quacks like a duck, it's a duck. AND THAT'S SCIENCE.

Unless it's a loon.

Actually, there's a flaw in your reasoning. It could be that Earth and Mars both were pelted by an external source, leaving rocks with similar properties behind. (Just because your neighbor's yard is filled with maple leaves and your yard has maple leaves in it doesn't mean that the leaves in your yard came from your neighbor's yard— they could have come from the next yard over, where the maple tree is.) These rocks could be more common on Mars because of either proximity to the source (say, the Asteroid Belt) or because Earth's more prominent geological and weather processes broke down its share of rocks (and its thicker atmosphere burned more of the meteors into vapor), or all of these. Or, yes, the rocks could be from Mars, though necessarily they would have had to have been expelled from Mars by a significant mass impact in order to be ejected at escape velocity and thus "fall" towards Earth.

One might point out that the survey missions to Mars are specifically planned to land in sites with interesting features to examine— like craters with lots of surface rocks scattered about. The "desert" areas of bland plains, not so much. So that's another element to consider— perhaps we're finding rocks similar to meteorites found on Earth because we're exploring a bunch of meteorites that fell on Mars.

I am, of course, pointing out the flaws in your simplified argument, not saying the claim is false. In this instance, I think the OFM's earlier expressed skepticism is understandable, absent a greater technical explanation than you have expressed.

I can't say much about Mars rocks, but that's pretty much how we source obsidian and other rocks used by prehistoric Americans to make stone tools. See this:

link

The best way I can describe it is that they blast the rock with this thing that looks like a Star Trek phaser and one of the outputs is a spikey graph with each spike indicating detected elements. The output reflects the precise chemical makeup of the rock at the moment it was formed. It's sorta like the rock's DNA. It also provides data on the conditions in which the rock had been formed. Like snowflakes, no two pieces of obsidian from different sources look exactly alike, and if the data is robust, the source of teh rock/obsidian can be determained with a high degree of certainty. Sourcing is important to archaeologists when considering possible trade relationships, or how far a given group of prehistoric Americans were willing to travel for good toolmaking materials.

I imagine astronomers use similar methods and equipment to determine the sources of meteorites.

The real clincher, from this site: link

But there is additional, positive, evidence that links them to the planet, which comes from gases trapped within the Elephant Moraine (EET) A79001 meteorite. This meteorite contains inclusions of black glass scattered throughout its mass. The glass was formed by shock melting of mineral grains, presumably during the impact event that lofted the meteorite from its parental surface.

Analysis of gas trapped within the glass during the impact shock shows that it is identical in composition to that of Mars' atmosphere (measured by the Viking landers in 1976). The only way that Mars' atmosphere could have become trapped in EET A79001 is if it came from Mars.

Thus EET A79001 comes from Mars, and since (on the basis of their oxygen isotopic composition) all the other SNC meteorites come from the same parent as EET A79001, then they too must come from Mars.

So those meteorites, at least, definitely came from Mars. Absolutely no room for doubt. And the cool thing is that the absolute evidence confirms the earlier hypotheses. The scientific method in action.

And jpattern for the points. Trapped gas identical to the Martian atmosphere pretty much answers the potential arguments I mentioned, and gives us a simple answer to the OFM's question. (Boosted of course by the evidence of shock melting produced by the impact that would have had to happen to loft the rocks on their interplanetary journey in the first place.)

Of course, maybe it wasn't an impact. Maybe it was intelligences greater than our own, watching from across the vast depths of space, studying our planet, so much more full of life than their dying one, planning, plotting, building, and at last launching themselves through the void to strike at us… only upon the penultimate moment of their invasion to discover that they had made two big mistakes— they were a heck of a lot smaller than we were, and they forgot to put hatches in their spaceship rocks.

The analysis of trapped meteorite gases was the first proof, even before the Viking Lander, I believe. The gas bubbles only matched the composition of the Martian atmosphere, gleaned from spectroscopic analysis. The Viking samples confirmed it.

Of course, maybe it wasn't an impact. Maybe it was intelligences greater than our own, watching from across the vast depths of space, studying our planet, so much more full of life than their dying one, planning, plotting, building, and at last launching themselves through the void to strike at us… only upon the penultimate moment of their invasion to discover that they had made two big mistakes— they were a heck of a lot smaller than we were, and they forgot to put hatches in their spaceship rocks.

I think Douglas Adams wrote something similar in the Hitchiker books.

While we are in SCi-FI mode, how about this?:

We are Martians

Mars is quite a bit smaller than the Earth, therefore it would have cooled first and formed a stable surface first. It would have also formed an atmosphere first. The possibility of forming life would have existed on Mars earlier too. Extremophiles!

Mars has the misfortune of being next to the Asteroid Belt (itself made from an even more unfortunate planet) and suffers many more impacts than does the Earth (thank God!) Some of these impacts blast chunks of the Martian surface into space. Some of these chunks fall to Earth (scientists estimate that a few tons of Martian rocks fall to Earth every year!!) These rocks carry dormant Martian soil extremophiles to a newly cooled and amino acid and nucleotide-sugar rich Earth surface. Life has found a foothold on Earth, seeded from Mars.

Voila!

Thanks for that, Bowman, I didn't know which came first, the Lander or the hypothesis.

Although Parzival's "intelligences greater than our own" is still in the running, too. :)