The Implications of 'Oumuamua on Panspermia

Panspermia is the hypothesis that life originated on Earth from the bombardment of foreign interstellar ejecta harboring polyextremophile microorganisms. Since the 2017 discovery of the comet-like body 'Oumuamua (1I/2017 U1) by the Pans-STARRS telescope, various studies have re-examined panspermia based on updated number density models that accommodate for 'Oumuamua's properties. By utilizing 'Oumuamua's properties as an anchor, we estimate the mass and number density of ejecta in the ISM (rho(m) [kg & sdot;au](-3) and rho n [au](-3)). We build upon prior work by first accounting for the minimum ejecta size to shield microbes from supernova radiation. Second, we estimate the total number of impact events C-n on Earth after its formation and prior to the emergence of life (approximate to 0.8 Gyr). We derive a conditional probability relation for the likelihood of panspermia for Earth specifically of <10(-5), given a number of factors including f(B), the fraction of ejecta harboring extremophiles and other factors that are poorly constrained. However, we find that panspermia is a plausible potential life-seeding mechanism for (optimistically) up to similar to 10(5) of the similar to 10(9) Earth-sized habitable zone worlds in our Galaxy.