NASA’s OSIRIS-REx Mission Finds Stardust in Asteroid Bennu Older Than the Solar System

In September 2025, scientists announced a surprising discovery: NASA's OSIRIS-REx mission — which collected samples from asteroid Bennu in 2020 — found tiny grains of stardust older than our Sun. These presolar grains make Bennu a “time capsule” of the early solar system. Along with ancient organic compounds from interstellar space, the Bennu material carries direct clues about the birth of our solar system and even the stars that exploded long ago. Researchers note that Bennu has preserved clues about the solar system's very earliest days.

Stardust Older Than the Sun

According to a trio of recently published papers, scientists analysed Bennu's rocks with powerful microscopes and chemical detectors, finding minuscule presolar grains — specks of dust from stars that existed before our Sun. These grains are smaller than a micrometer and carry unusual chemical fingerprints from the nuclear reactions in their parent stars.

In one study, researchers reported “we found stardust grains with compositions that predate the solar system”. In other words, Bennu contains direct samples of ancient stardust. These grains act like fossils from long-dead stars, revealing how their material was scattered into the early solar system.

Why Bennu Matters

NASA's OSIRIS-REx spacecraft traveled to Bennu, mapped its surface for a year, and in 2020 collected a rock sample. Bringing these samples to Earth allows scientists to analyze them in detail. Researchers say this gave “very valuable geological context that we cannot get from meteorites,” and that “we could only get the answers we got because of the samples”.

Most meteorites burn up or lose context, so Bennu's pristine material is rare. By studying it in labs, scientists can directly test how planets built up from this stardust. In fact, Bennu has “preserved clues about the earliest days of our solar system”