Yet Another Are We Martians?

Quite a lot of people have been submitting the Wired article about the "discovery" of two strains of bacteria that could be extra-terrestrial in origin. Carrying along with that beat, the Boston Globe has a report about where life on Earth came from, and whether it was Martian in origin. *Rant* The Wired article in particular makes me cross. Two strains in question, to my knowledge, have been known by biologists for at least a couple decades. The fact that they /might/ be able to survive extra-terrestrial conditions doesn't mean they are extra-terrestrial. In fact, the environments where bactera like this are often found, like deep sea vents, are in many ways just as "bad" as extra-terrestrial travel. Perhaps it's a pot-kettle situation with me, but bad science coverage irritates me greatly. */Rant*

Comments

Oh puh-leese!

[Tau Zero]

In the Wired article you'll find this gem:

The problem is to determine whether any of these bodies did in fact carry life, and then to find out where life began if it did not originate on Earth.

This gives the impression that the author thinks the original rocks from Mars, some billions of years old, are still sitting around somewhere waiting to be examined. HELLO! They've long since weathered into clay, been pressed into shale, and been hung as blackboards and roof tiles - in the Cretaceous! And a time or two since then.

There's only one thing that could give a solid (though not irrefutable) indication that Earth life originated on Mars: we go to Mars and we find a number of varieties of life, only one or two of which biochemically match the major categories found on Earth. Articles like the Wired piece are a waste of bits.
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The Article Everyone Missed

[Sargent1]

It's a shame no one else has noticed the second article Wired posted a little while later...

They Published from Outer Space
AP

3:15 a.m. 13.Jan.2000 PST
The same astronomers who reported on Wednesday they had found a tough but peaceful pair of bacteria that might have been able to survive the arduous trip from Mars, back when the Red Planet could have supported life, have also discovered that a paper copy of Wired magazine is also capable of surviving the trip. From this they theorize that Wired is from Mars, or possibly Uranus.

Sargent

The impact

[delevant]

I recently saw a TV science show talking about how the moon came into existance -- the show took the angle that a "moon-creating impact" must have occurred at some point in the distant past.

Basically, the idea was that the Earth got hit by another planet, at a fairly oblique angle. The show argued that this would explain why the Earth has an iron core (we got most of the iron from the other planet, in addition to the one we had already), and so on.

Since the impact was so cataclysmic, everything on the pre-impact Earth (Earth Mk I) got annihilated, and everything on the impacting planet gets killed too (since both planets get liquified).

My question is this: if we assume that the moon-creating impact happened, then WHEN did it happen, and how does that affect the possibility of life arriving on Earth from elsewhere in the solar system?

I mean, if everything on Earth (even bacteria) got killed only a couple billion years ago, it makes it somewhat unlikely that anything could have arrived from Mars post-impact, given the purported rates of Mars Rock Impacts mentioned in the article . . .

I dunno; it struck me as interesting.