> The impact on earth to cause ejecta to have escape velocity would probably need to be larger than on mars.
significantly larger, because it has to get through our atmosphere once on the way in, and then the ejecta has to do it again on the way out, keeping in mind that drag is proportional to velocity squared, and that whatever ejecta is making this trip has to find a way not to get cooked into sterility by impact energy or friction with the air....
Too many extra factors are in play, each of which adds an exponent to the unlikelihood. But that's just my uneducated opinion, I'm certainly open to discussion.
significantly larger, because it has to get through our atmosphere once on the way in, and then the ejecta has to do it again on the way out, keeping in mind that drag is proportional to velocity squared, and that whatever ejecta is making this trip has to find a way not to get cooked into sterility by impact energy or friction with the air....
Too many extra factors are in play, each of which adds an exponent to the unlikelihood. But that's just my uneducated opinion, I'm certainly open to discussion.