SUMMARY: When scientists announced that they had found evidence of past life in a meteorite from Mars in 1996, it set off a controversy that has been going back and forth even now. The latest research, published in the journal American Mineralogist casts doubt that it's life that was in the space rock. The original discoverers believed that magnetite in the rock was formed by bacteria, but this new paper shows that it can also be caused by an inorganic process, which can be duplicated in the laboratory when iron-bearing carbonates decompose under high heat (such as atmospheric reentry).

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This is an interesting story, Fraser.

While cleaning up some old files today, I was reminded of a controversy in the 1960s-1980s about the low Xe/Kr ratio in air --- about a factor of 10 lower than that in meteorites.

In the 1960s, my first graduate student, Robert Canalas, had measured noble gases in shales and found much higher Xe/Kr ratios there. We speculated that Xe from air had been selectively depleted by adsorption onto sediments.

If correct (and it was disputed by some) then the Xe/Kr ratio in Mars' atmosphere may indicate the presence or absence of sediments there.

Sediments would indicate the presence of water and the possiblity of life.

With kind regards,

Oliver
http://www.umr.edu/~om

i dont really have much to say

I disagree! I was given to understand that meteors only heat up on their surfaces, that they were actually cold to the touch almost immediately after landing. I know with the ablative heating process used in ICBM's, Mercury, Gemini and Apollo that the material that was vaporizing formed a plasma that actually reflected more heat than it conducted into the surface.

Hi, Scott.

You are right that that meteorites only heat up on their surfaces. In fact, frost frequently forms on the outside after they land if the humidity is high.

So I don't understand. With what do you disagree?

With kind regards,

Oliver
http://www.umr.edu/~om