If we find other life in our galaxy how would we know its not caused by panspermia by Earth from the various large impacts we've had? One impact that comes to mind is the Chicxulub asteroid. A google search reveals that 70 billion tons of Earth's material was ejected from the atmosphere and into space with some debris potentially hitting Mars and Jupiter. Of course it also states that much of the material fell back onto the surface, but let's say 7 million tons of it or 1/1000th of the material was ejected into space. Thats still 7 million tons. Of course one could argue that there is no way any life including bacteria could have survived ,but who really knows. All it takes is for some extremophile bacteria to survive the immediate impact aswell as the launch into space.…