How did life first occur on Earth? Did it begin with a singular event or did life develop gradually? And what if our most ancient ancestors, those first life forms to inhabit the Earth, actually came to this planet from somewhere else? I’m Jim Metzner, and this is the Pulse of the Planet, presented by the American Museum of Natural History.
Chris McKay is a scientist in the Space Science Division at NASA’s AMES Research Center. Part of his research involves the study of meteorites, rocks flung to Earth through space. He tell us that these meteorites may once have transplanted life from one planet to another.
“It’s interesting to speculate how life could transfer from planet to planet. We have rocks on Earth that came from Mars and these rocks could very easily have carried micro-organisms if there were micro-organisms on the surface of Mars, to Earth and vice versa. So life could have originated from Mars and been carried to Earth. Life could have originated on Earth and carried to Mars.”
Ah, but how could rocks here on Earth have come from Mars?
“Well these little rocks are kicked off by a comet or asteroid slamming onto the surface of Mars, kicks off the rock with enough velocity that the rock has the escape velocity from the planet. Goes in orbit around the sun and after some random number of orbits around the sun, by chance could fall into the Earth. And we know that these rocks are intact. They are not destroyed by either the ejection or the reentry and an organism in the center of the rock could easily have survived. If that rock is then weathered by water or, or kicked apart by some other process, that organism could be released and it could propagate on a new world. (1:00:33)We don’t have any evidence that life on Earth came from Mars or that life from Earth was sent to Mars via vis this mechanism. But it’s possible. ”
Pulse of the Planet is presented by the American Museum of Natural History. Additional funding for this series has been provided by the National Science Foundation. I’m Jim Metzner.