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Scientists have made a surprising discovery in a sample returned from an asteroid. NPR's Geoff Brumfiel reports it contains tiny particles from far beyond our solar system.
GEOFF BRUMFIEL, BYLINE: NASA researcher Ann Nguyen studies dust.
ANN NGUYEN: A general comment that I get is, I've got dust under my bed you can study (laughter). I'm like, no, I don't study that kind of dust. I study stardust.
BRUMFIEL: Now, you've probably heard somewhere before this idea that we're all made of stardust. That's because stars forged nearly all the elements in the universe. The atoms that make up our bodies were themselves made inside the core of a star somewhere else.
NGUYEN: The core is extremely hot. And then, as you go out in the atmosphere beyond, it's cool enough so that gas can form and aggregate into tiny grains.
BRUMFIEL: Cosmic dust motes. Sometimes the star would explode, blowing the little grains across the galaxy like dandelion seeds. Other times the grains would drift away on their own, traveling on the stellar wind into deep space.
NGUYEN: Probably a lot of them do get destroyed. But some of them survive, and they make it to our region of the universe where our solar system formed.
BRUMFIEL: The stardust swirled and clumped and eventually became part of the sun, the planets and, yes, us.
NGUYEN: These materials all played a part in our life here on Earth.
BRUMFIEL: The problem is the original dust grains were very fragile, and so when they became part of this new solar system, they were broken up and blended. Their origins were lost. Scientists like Ann Nguyen want to know more about where they came from.
NGUYEN: Yeah, that is one of the big questions in cosmochemistry.
BRUMFIEL: Then, in 2019, a Japanese spacecraft visited a little asteroid called Ryugu. It scooped up a tiny sample, and an even tinier portion of that sample found its way to Nguyen's lab. She fired up her best dust analyzers and got ready to nerd out on some asteroid grit.
NGUYEN: I kind of thought, you know, the results I would get would be kind of run-of-the-mill.
BRUMFIEL: But as her team writes in the journal Science Advances, the sample contained organic molecules from deep space, pieces of ancient rock from the very edge of our solar system and many tiny grains of perfectly preserved stardust.
NGUYEN: I cannot tell you the excitement I felt and just euphoria almost.
BRUMFIEL: Because these grains are part of the story of how we got here - blown on an interstellar wind long ago.
Geoff Brumfiel, NPR News.
(SOUNDBITE OF SONG, "STARDUST")
HOAGY CARMICHAEL: (Singing) Though I dream in vain in my heart, it will remain my stardust melody, the memory of loves' refrain. Transcript provided by NPR, Copyright NPR.
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