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A trillion extraterrestrial civilizations have potentially existed over the course of cosmic history, says a prof.
During the second mission to the moon in 1969, Apollo 12, the crew brought back a camera that had been sent some two and a half years earlier. When they returned, the camera underwent extensive testing including microbiological analysis. Much to their surprise, they found a colony of earthly bacteria; apparently the microbes had survived the inhospitable lunar environment.