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Transfer of Life-Bearing Meteorites from Earth to Other Planets
Tetsuya Hara, Kazuma Takagi, Daigo Kajiura
(Submitted on 8 Apr 2012)

The probability is investigated that the meteorites originating on Earth are transferred to other planets in our Solar System and to extra solar planets.
We take the collisional Chicxulub crater event, and material that was ejected as an example of Earth-origin meteors.
If we assume the appropriate size of the meteorites as 1cm in diameter, the number of meteorites to reach the exoplanet system (further than 20 ly) would be much greater than one. We have followed the ejection and capture rates estimated by Melosh (2003) and the discussion by Wallis and Wickramasinghe (2004). If we consider the possibility that the fragmented ejecta (smaller than 1cm) are accreted to comets and other icy bodies, then buried fertile material could make the interstellar journey throughout Galaxy. If life forms inside remain viable, this would be evidence of life from Earth seeding other planets.
We also estimate the transfer velocity of the micro-organisms in the interstellar space. In some assumptions, it could be estimated that, if life has originated $10^{10}$\ years ago anywhere in our Galaxy as theorized by Joseph and Schild (2010a, b), it will have since propagated throughout our Galaxy and could have arrived on Earth by 4.6 billion years ago. Organisms disperse.

I am not sure how many $10^{10}$\ is as I am unfamiliar with the $\ system of measuring stuff.

Dear authors of this paper and in particular this sentence:

"As the distance to Gl 581 is 20 light years,"

Not 65 million years ago it wasn't. GL 581's radial velocity is about 10 km/s or 1/30,000 times the speed of light. That means over sixty-five million years, it has moved almost 2200 light years from our perspective (As well, the Milky Way has rotated about one quarter since the dinosaurs got killed: Sol and GL 581 were both about 40,000 ly anti-spinward from where they are now).

Also posted at Dreamwidth, where there are comment count unavailable comment(s); comment here or there.

They should make it clear they mean a star like GL 581 because otherwise some SF writer is going to read this paper and not only use it as the basis of a very badly thought-out panspermia book in which protosimians were blasted across interstellar space 65 million ago, they will also think Alpha Centauri has been nailed in place 4 LY from us for the last four billion years. I'm only protecting the genre here.

Do you really think that the kind of author who would make that kind of mistake would read deeply enough to avoid it even if the authors put a flashing, scrolling banner in the abstract?

I'm thinking of Dan Simmons putting Epsilon Indi and Epsilon Eridani about a half light-year from each other in one of the Endymion books on the basis of some list of the nearest stars' distance from Sol.

Hey, they're both in the Epsilon system, right?