Re: Too much fuss about contamination
"There's a reason that most meteorites that are found on Earth are of the metallic type"
I'm absolutely for sure not a meteorite expert. But my understanding is that the reason most reported meteorites are metallic is possibly selection bias. Metallic meteorites are relatively recognizable, magnetic, and pretty durable whereas stony meteorites tend to look more like just another rock, laugh at magnets, and some decompose fairly readily in wet environments. I've read that in Antarctica where all the rocks on the icecap are assumed to have arrived by air, the percentage of metallic objects is quite low.
As to whether living critters can by blasted into space from Earth. I dunno. Too many variables. For one thing, there's that whacking great initial acceleration required. Because of drag during exit, initial velocities well in excess of escape velocity of 11.2 km/s would be needed. OTOH, algal cysts ("acritarchs") are really durable. And they've been around for billions of years and presumably many Earth-bolide encounters. For large impactors, there may be some possibility of single celled organisms riding along inside rocks. My understanding is that variety of living creatures were found living deep in the Kola super-deep borehole despite the great heat and pressure. Maybe some of the creatures living deep in the Earth can tolerate cold and millenia in transit as well.
Biting the hand that feeds IT
