Life on Earth could be descended from space-faring microbes from Mars — or even further beyond, riding here on an interplanetary highway of asteroids. Extremophile bacteria may be resilient enough to survive the intense 3-stage journey, by repairing their own damaged DNA or hibernating for the long, deadly journey through space. The chemistry of life could even be spreading across star-systems to other parts of the galaxy, connecting biologies together... see more