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Coffee!! Who’s the Man from Mars? You’s the Man from Mars!

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David L. Chandler asks,

Are we all Martians? According to many planetary scientists, it’s conceivable that all life on Earth is descended from organisms that originated on Mars and were carried here aboard meteorites. If that’s the case, an instrument being developed by researchers at MIT and Harvard could provide the clinching evidence.- “Are you a Martian? We all could be, scientists say — and new instrument might provide proof” (Physorg March 23, 2011)

The article provides a useful summary of the state of the evidence, capped by

Christopher McKay, an astrobiologist at NASA-Ames Research Center in California who specializes in research related to the possibility of life on Mars, says this work is “very interesting and important.” He says, “it is not implausible that life on Mars will be related to life on Earth and therefore share a common genetics. In any case it would be important to test this hypothesis.”

Parts of the project I don’t get: The idea seems to be to search for sequences of DNA and RNA molecules that are “nearly universal in all forms of terrestrial life.”

Okay, but isn’t (almost) universal common descent the accepted explanation for that? Why drag Mars into it?

The researchers hope to find “living microbes” or their remains in Martian soil samples, and analyze them for the nearly universal code. Suppose they find some. Why should we suppose that we came from Mars rather than that the microbes came from Earth? The latter is vastly more plausible, I would say.

So far, it sounds like great sci-fi TV, and it would be a shame to take Occam’s Razor to it, so we won’t.

Denyse, Good comments - but I think there is an explanation for why they say what they do. On "dragging Mars into it" - I think all this does is make "universal common descent" cover a little bit more of the universe than we might have expected. On the point of it seeming more plausible that microbes came from Earth - the article explains that it is far more likely they came from Mars (about 100 times more likely from Mars, in fact). This is almost entirely based on the physics. Mars is a much smaller world, so it's easier (dynamically) for material thrown up by meteorite strikes to reach the much lower Martian escape velocity (and not fall back to the surface) than would be the case on Earth. Secondly, Mars is further from the Sun than Earth is. So, in order to "fall" towards the Sun and reach Earth, the material has to lose energy - i.e. go into a less energetic orbit. Going from Earth to Mars, the material would need to increase energy. The former is typically easier to do than the latter. So if there is life on Mars and it's relate to life on Earth, then it's much more likely that it originated on Mars. Time to look for a new location for the Garden of Eden? And looking at Mars now - what a Fall that was! Grunty
Thanks for an interesting article Eugen

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