Earth rocks could have taken life to Titan

Boulders blasted away from the Earth's surface after a major impact could have travelled all the way to the outer solar system, new calculations reveal. The work suggests that terrestrial microbes on the rocks could in theory have landed on Saturn's giant moon, Titan. But whether they could have survived once there remains unclear.

The fact that meteorites from the Moon and Mars have landed on Earth confirms that impacts on solar system bodies can launch rocky debris to other planets. And previous studies have suggested that any life on the rocks could have survived the launch blast and the radiation and chill of the journey through space, assuming it lasted less than a few million years.

Such hardiness raises the possibility that life on Earth itself was seeded from space – a concept called panspermia. But now, researchers led by Brett Gladman of the University of British Columbia in Vancouver, Canada, have analysed the reverse situation – that life on Earth seeded other bodies in the solar system. Gladman presented the results on Thursday at the Lunar and Planetary Science Conference in Houston, Texas, US.

He says only boulders at least 3 metres across could punch out through the Earth's atmosphere and escape the planet's gravity, and that only extremely powerful impacts could achieve this. The cause of such impacts would be comets or asteroids between 10 and 50 kilometres wide, Gladman told New Scientist: "The kind of thing that killed the dinosaurs."

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