The initial constituents that coalesced to form entities within our Solar System were sourced from stellar remnants, the primordial molecular cloud, and the protoplanetary accretion disk. Remnants such as asteroids, which have not undergone planetary differentiation, preserve records of these foundational materials. Nevertheless, geological phenomena, including hydrothermal alteration, possess the capacity to profoundly modify their chemical makeup and composition. Within a recent scientific investigation, researchers conducted an in-depth analysis of the elemental and isotopic signatures present in samples procured from the asteroid Bennu, aiming to elucidate the provenance and nature of the substances assimilated by its progenitor body.
This mosaic image of asteroid Bennu is composed of 12 images collected on December 2, 2018 by OSIRIS-REx’s PolyCam instrument from a range of 15 miles (24 km). Image credit: NASA / NASA’s Goddard Space Flight Center / University of Arizona.
“Our findings indicate that Bennu exhibits an elemental composition remarkably congruent with that of the Sun,” remarked Greg Brennecka, a scientist at LLNL.
“Consequently, the material retrieved from Bennu serves as an exceptional benchmark for ascertaining the initial composition of the entire Solar System.”
“It is truly extraordinary that Bennu has maintained its integrity over such an extended period without experiencing high temperatures that would degrade certain constituent elements.”
The intricate processes governing planetary formation are a subject of ongoing scientific inquiry, and comprehending the initial elemental makeup of the Solar System is akin to possessing the precise list of ingredients required for baking a cake.
“Armed with this comprehensive inventory of ingredients, we now possess a more refined understanding of how these disparate elements converged to give rise to the planets within our Solar System, and ultimately, to Earth and the life it sustains,” stated Dr. Brennecka.
“To undertake a meaningful exploration of our origins, the foundational step necessitates an understanding of the Solar System’s primordial composition.”
A view of the outside of the OSIRIS-REx sample collector. Sample material from asteroid Bennu can be seen on the middle right. Image credit: NASA / Erika Blumenfeld / Joseph Aebersold.
By successfully returning an unadulterated sample to Earth, thereby circumventing any terrestrial contamination, NASA’s Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission has unlocked novel avenues for scientific discovery.
“The sheer volume of invaluable data that can be extracted from returned sample material within a laboratory setting is truly astounding,” commented Quinn Shollenberger, an LLNL scientist.
“Without the presence of the sample here on Earth, it is simply not feasible to address the profound questions surrounding our origins.”
“A key objective of our research is to delineate the complete spectrum of elements that constituted the Solar System at its inception, and their respective abundances. Bennu provides us with the means to ascertain this crucial information,” explained Jan Render, an LLNL scientist.
To achieve these groundbreaking results, the researchers meticulously pulverized the asteroid material into an exceedingly fine powder and subsequently subjected it to dissolution in an acidic medium.
Following this preparation, the resultant solution was introduced into a sophisticated array of mass spectrometers, which then meticulously quantified the concentrations of a substantial portion of the elements present in the periodic table.
Subsequently, the scientific team has embarked on a process of segregating the sample based on individual elements, and a significant milestone has been reached with the successful analysis of the isotope ratios for several elements thus far.
“A distinct advantage of conducting research at a national laboratory lies in the exceptional analytical instrumentation and the profound expertise available for operating cutting-edge technologies,” noted Josh Wimpenny, an LLNL scientist.
“The synergistic synergy of having these advanced capabilities consolidated in a single location is exceptionally rare, and it significantly enhances our ability to derive maximum benefit from these invaluable materials.”
“We have successfully traced the provenance of the primordial materials that were incorporated into the precursor of Bennu,” stated Dr. Ann Nguyen, a researcher affiliated with NASA’s Johnson Space Center.
“Our investigations have uncovered stellar dust grains possessing elemental compositions that predate the formation of the Solar System, organic compounds likely synthesized in the vastness of interstellar space, and high-temperature minerals that originated in close proximity to the Sun.”
“All of these component parts underwent extensive transit across vast cosmic distances before reaching the region where Bennu’s parent asteroid ultimately took shape.”
The discoveries have been formally documented and published within the esteemed journal, Nature Astronomy.
_____
J.J. Barnes et al. The variety and origin of materials accreted by Bennu’s parent asteroid. Nat Astron, published online August 22, 2025; doi: 10.1038/s41550-025-02631-6
