San Francisco - It would be very hard for microbes to get all the way from Earth or Mars out to the ocean moons, a new study suggests. If there are creatures swimming in the buried oceans of the outer solar system, they're probably not related to us, new research suggests.
Some scientists believe that life has hopped from world to world around the solar system, aboard chunks of rock blasted into space by comet or asteroid impacts. Indeed, there's a school of thought that the life teeming here on Earth is actually native to Mars, which likely boasted habitable conditions earlier than our own planet did. (This rock-riding idea is known as "lithopanspermia," a subset of the broader panspermia notion, which envisions spread by whatever means, either natural or guided by an intelligent hand.)
But what are the odds that such putative pioneers could colonize the habitable real estate much farther out — specifically, the Jupiter moon Europa and the Saturn satellite Enceladus, both of which harbor big oceans of salty liquid water beneath their ice shells?