What are the odds that we’re all alien life forms? Even if your family has been in your home town for generations, there’s a chance that all life on Earth originated elsewhere, and was somehow transported to this planet billions of years ago. The idea is known as panspermia, and is usually based around the notion that a large asteroid broken off or expelled from a planet carried some hearty organisms along through space, eventually crashing into Earth where those organisms spread and diversified. A new wrinkle in this model is being suggested now, as simulations have found that a large rock may not have been a necessary component for life to travel— biological particles in a planet’s upper atmosphere may have been able to be launched by dust alone.
While there’s not enough air to breath in space, it’s not a complete vacuum either. In addition to larger and smaller asteroids, there’s a fair amount of dust that either never coalesced into a larger object, or was broken off a larger object in a collision. Researchers from the University of Edinburgh found that some of that dust is zipping along at a brisk 156,586 miles per hour, giving them a significant amount of energy to shove other particles that might be suspended high above a biologically active planet’s surface. For example, if a microscopic organism was suspended 93 miles over the Earth’s surface, around the altitude of auroras, a collision with space dust could knock it past the planet’s gravitational pull towards a new home (assuming it survived the collision.)
What life could survive in space?
Once biological material was on its way, the trip might be easier to survive than you’d think. Some bacteria have been found to survive in the generally hostile environment of outer space, and plants and animals do better than expected as well. However, a living creature wouldn’t be strictly necessary to seed life on a new planet. Even the delivery of organic molecules like amino acids would make a huge difference in kick-starting an ecosystem, some of which have already been linked to meteorites found on Earth. If these molecules could be sent sailing from mere dust as well, then the possibilities really open up for interstellar pollination.
Source: Space dust may transport life between worlds, University of Edinburgh News