The question is more:|
The chances of bacteria adhereing to a meteor, plus the chances of said meteor* hitting a planet capable of supporting life, plus the chances of the bacteria reanimating and seeding the planet with life,
The chances of bacteria and life evolving on the planet in the first place (which by our very existence must be possible - not everything can have come from sonewhere else).
Second seems more straightforward to me.
*yes I know a meteor by definition will crash into a planet, don't split hairs.
LB, you really are a massive geek.