Transfer of Life-Bearing Meteorites from Earth to Other Planets
  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. 
Tetsuya Hara, Kazuma Takagi and Daigo Kajiura
astro-ph.EP