If the bacteria floated up to LEO (which is very possible) the impact was likely in the meters/second range because it would have had to match the orbit closely

If the bacteria floated up to LEO (which is very possible) the impact was likely in the meters/second range because it would have had to match the orbit closely enough. Because bacteria are so small (and the filaments they use to support the cell membrane is so strong) it would take an extreme impact to "splatter" them. Remember also that archaeic bacteria (as well as simple multicellular organisms) live on the bottom of oceans like the Mariana Trench where the pressure is over 1,000 atmospheres (enough to turn you into a miniature hockey puck).