[Rockhounds] What Dust From Space Tells Us About Ourselves

[Kreigh Tomaszewski]

Every year, roughly 10 particles of space dust land on each square meter of
Earth’s surface. “That means that they are everywhere. They are on the
streets. They are in your home. You may even have some cosmic dust on your
clothes,” said Matthew Genge <https://www.imperial.ac.uk/people/m.genge>, a
planetary scientist at Imperial College London who specializes in these
alien dust grains, known as micrometeorites.

Round and multicolored like tiny marbles, micrometeorites are as
distinctive as they are ubiquitous, yet they escaped notice until the
1870s, when the HMS Challenger expedition dredged some up
<https://oceanexplorer.noaa.gov/history/docs/science.html> from the bottom
of the Pacific Ocean. (On land, the accumulation of terrestrial dust tends
to overwhelm and conceal the cosmic kind.)

For a century, scientists thought that the strange spherules found on the
seafloor had dripped off the molten surfaces of larger meteors as they
crashed through the atmosphere. In fact, cosmic dust floats here from space
rocks hundreds of millions of miles away, bearing tiny messages.

For 30 years, Genge has been deciphering those messages, one grain at a
time.

He began his career just as Antarctica was identified as a bountiful new
source of micrometeorites. Strong southerly winds help sweep away earthly
debris, so that as much as 10% of the dust lodged in the ice comes from
space. “I got to do a lot of the easy stuff,” Genge said, like figure out
“what they’re made of, what they look like, what the different types are.”
Since then, he and other micrometeorite specialists — a small enough
community that he “knows the children of most of them” — have gleaned much
more information from the dust. Recently, Genge has been interpreting
messages the space dust carries, not about its origins, but about its
destination: Earth at different points in the planet’s history.

https://www.quantamagazine.org/matt-genge-uses-dust-from-space-to-tell-the-story-of-the-solar-system-20210204/