> Regarding planetary contamination, with the amount of meteorites hitting ocean I do not think we have anything to worry about. The amount of oxygen in the at

> Regarding planetary contamination, with the amount of meteorites hitting ocean I do not think we have anything to worry about. The amount of oxygen in the atmosphere helps a lot. The onset of photosynthesis caused a mass extinction ~two billion years ago. https://en.wikipedia.org/wiki/Great_Oxygenation_Event https://en.wikipedia.org/wiki/Great_Oxygenation_Event I love that name. It sounds like some kind of a party.