Space Dust Is Carrying Tiny Bits of Life on Earth to Far Reaches of the Milky Way—Potentially Seeding Other Planets With Life

Space dust is everywhere—including this nebula where stars are being born and hitting Earth's atmosphere. NASA/JPL-Caltech/Harvard-Smithsonian CfA

Since the Sputnik launch in 1957, humans have been energetically catapulting all sorts of things into space, quite plausibly offering hitchhiking bacteria the ride of their lives. But it turns out life could have been catching much smaller lifts away from Earth for much longer than humans have been around, much less exploring space.

That's according to a new paper published in the journal Astrobiology, which asks whether tiny particles of space dust could ferry life off the planet and across the solar system—or even across the galaxy. The scientist behind the paper, Arjun Berera, is a particle physicist at the University of Edinburgh in the U.K.

Berera was inspired by the sheer bulk of space dust that visits Earth—about 60 tons every single day (all this dust hitting Earth probably helps shape how the planet's atmosphere and plant life works.) Some of it hits Earth head-on, but some just slides by. The particles are tiny, with even the biggest pieces weighing a fraction of a pound, and super fast, sometimes clocking as fast as 40 miles per second.

According to Berera's calculations, the stream of dust could be strong enough to bang against tiny ingredients of life out of the upper atmosphere and shoot them away like billiard balls. That force could send them to neighboring planets in the solar system, or potentially even into neighboring solar systems.

That idea is predicated upon the presence of living organisms up in the outer layers of Earth's atmosphere, which might sound wild but is actually a known phenomenon: scientists think the critters up there may even affect the weather. Even if those are too big to survive a planetary exit, smaller particles crucial to life could certainly fling out from Earth's atmosphere when ricocheted by space dust.

Berera's idea is that dust particles zooming into Earth's atmosphere can sweep these bacteria—and even more easily smaller ingredients of life—off their feet and out into space. There, they could be snatched up by something larger and more stable, like a comet, to continue their journey.

Berera is cautious about his proposal, noting that it's a rough ride out of Earth's atmosphere and the trip doesn't get any easier from there. To flee the whole solar system, not just Earth, would be another game of chance, which he thinks any life would likely lose. But he counters that if this scenario works, it would be happening continuously, unlike, say, the dramatic but rare asteroid collisions that also send material from Earth flying into space.