Meteorites are messengers from the depths of primordial time—cast-off fragments of asteroids and comets that formed alongside our sun from raw materials predating our star itself. But their messages are often muddled by their final, fateful encounter with Earth—charred in their fiery plunge through our planet’s atmosphere and contaminated by our world’s ever-shifting environmental tumult. And unlike a typical piece of lost mail, they don’t come with a return address to reveal their provenance. But what if the scientists wishing to be historians of our solar system’s earliest days could sidestep these problems? Rather than relying solely on the random, scattered chapters of cosmic history from meteorites, wouldn’t it be better to directly visit space’s most ancient archives—the asteroids and comets—to bring back entire geologic books to read?
NASA’s Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft did just that in 2020, when it dove down to the surface of the near-Earth asteroid Bennu and retrieved some rocks dating back 4.5 billion years before bringing them back to Earth last September in dramatic fashion. It’s not the first (or second) spacecraft to burgle from an asteroid. But it retrieved the largest sample to date: a whopping 121.6 grams of pristine material from the solar system’s dawn.
Almost immediately after the sample return capsule landed on Earth, scientists began their forensic examinations. And earlier this month at the Lunar and Planetary Science Conference in The Woodlands, Tex., they presented their first in-depth findings for all the world to see. Their analyses are preliminary, but it seems that Bennu’s original form was shockingly familiar across the vast gulf of eons. Billions of years ago Bennu was apparently part of a water-soaked world now long lost and otherwise forgotten, one with a beating geologic heart and an abundance of prebiotic organic…
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