Meteor impacts blasted Martian surface material into space and it eventually entered Earth's atmosphere and rained down on the planet. AFAIK, heat is the enemy of bacteria, not acceleration -- at least not acceleration of the magnitude experienced by such ejecta. Presumably, some of this bacteria would be shielded from the intense heat of impact and entry into the Earth's atmosphere since it would be inside Martian rocks (and these we know do occasionally survive intact). Conceivably, it wouldn't take much to seed Earth with life. What I'd like to know is just how much acceleration a bacterium can survive. 100g's? 1000g's? Has anyone ever done the experiment?
I thought most meteors burned up in the earths atmosphere.