Bennu asteroid samples reveal Jupiter's role in shaping its primordial material

By the Everything Space news desk · 23 Sep 2026 · written from the sources below

Image: Phys.org

Isotope analysis of returned Bennu samples suggests the asteroid formed near the water-ice line under Jupiter's influence, reshaping theories of early solar system chemistry.

Analysis of material collected from the asteroid Bennu by NASA's OSIRIS-REx mission has produced new evidence about how the asteroid, and possibly the building blocks of Earth, came together. Researchers at ETH Zurich examined iron, titanium and chromium isotopes in a small portion of the roughly 120 grams of Bennu material returned to Earth in 2023, uncovering a chemical fingerprint that links Bennu to the asteroid Ryugu and a rare class of meteorites known as CI chondrites.

The isotopic similarities among these three types of primitive material suggest they formed from the same reservoir of cosmic dust, distinct from other asteroids, meteorites and planets studied so far. This challenges earlier assumptions that Bennu formed in the solar system's distant outer reaches, in a region similar to where comets originate, and that it formed relatively late in the solar system's history.

Instead, the data point to a different birthplace: a zone near the water-ice line, where water vapor freezes and material from both the inner and outer solar system could mix roughly 4.5 billion years ago. In this zone, ice may have acted like a binding agent, gluing together fine dust particles from different regions of the early solar system.

The research team proposes that Jupiter played a central role in creating this mixing zone. Because Jupiter formed quickly, within about a million years of the sun's birth, it effectively blocked larger chunks of material from crossing its orbit while allowing fine dust to flow around it and combine near the ice boundary. This process, researchers suggest, explains why Bennu's material is rich in water and closely resembles the sun's own chemical composition, since fine dust throughout the early disk was well mixed.

Because Bennu's material appears to have changed very little since the solar system's formation, its composition offers a rare window into the ingredients that ultimately built the rocky planets, including the water and organic compounds needed for life. Researchers now want to know whether other asteroids share Bennu and Ryugu's isotopic signature, and how much of a role early Jupiter played in concentrating fine dust.

Interest in this line of research is expected to continue with an upcoming Japanese sample-return mission to the Martian moon Phobos, expected to launch soon, though the samples are not scheduled to reach Earth until 2031.

Written in Everything Space’s own words by our news-desk model from the sources above, and checked against them in code: every number in this report appears in its sources, and no sentence is copied from them.