In “The Amazing Trajectories of Life-Bearing Meteorites from Earth” Technology Review/Physics Archiv blog, 04/11/2012), KFC reports,
The asteroid that killed the dinosaurs must have ejected billions of tons of life-bearing rock into space. Now physicists have calculated what must have happened to it.
Today, we get an answer from Tetsuya Hara and buddies at Kyoto Sangyo University in Japan. These guys say a surprisingly large amount of Earth could have ended up not just on the Moon and Mars, as might be expected, but much further afield.
In particular, they calculate how much would have ended up in other places that seem compatible for life: the Jovian moon Europa, the Saturnian moon Enceladus, and Earth-like exoplanets orbiting other stars.
Their results contain a number of surprises. First, they calculate that almost as much ejecta would have ended up on Europa as on the Moon: around 10^8 individual Earth rocks in some scenarios. That’s because the huge gravitational field around Jupiter acts as a sink for rocks, which then get swept up by the Jovian moons as they orbit.
Hara and co go further and estimate how much ought to have made its way to Gliese 581, a red dwarf some 20 light years from here that is thought to have a super-Earth orbiting at the edge of the habitable zone.
They say about a thousand Earth-rocks from this event would have made the trip, taking about a million years to reach their destination.
Of course, nobody knows if microbes can survive that kind of journey or even the shorter trips to Europa and Enceladus. But Hara and buddies say that if microbes can survive that kind of journey, they ought to flourish on a super-Earth in the habitable zone. More.
So when we meet Them, it won’t be a surprise if they are a lot like us?