We haven't found any martian life, but there is life on Mars: life we sent there, says NASA's planetary protection officer, Catharine A. Conley. Bacteria, pollen spores, and other pieces of life have traveled millions of miles inside our spacecraft, and we have reason to believe they could have survived the journey (life on the outsides of the craft would have been killed by exposure to UV light outside of Earth's atmosphere), and are now persisting on the Red Planet. "The saving grace to all this," Conley says, "is that the surface conditions on Mars are pretty hostile to Earth life, so it's not very likely that those organisms could actually reproduce, or even survive if they came off the spacecraft." If they're doing anything at all, they're just sitting there.
