Asteroid Bennu holds clues to the origin of our solar system

Sep 12 2025
Vial containing powdered sample of asteroid Bennu. Credit: NASA Goddard Space Flight Center
Vial containing powdered sample of asteroid Bennu. Credit: NASA Goddard Space Flight Center

In August, results from the first geochemical analyses of samples collected from asteroid Bennu by NASA’s OSIRIS-REx spacecraft were published in three journals, including Nature Astronomy. Dr. Dominique Weis, Director of the Pacific Centre for Isotopic and Geochemical Research (PCIGR) and Killam Professor in the Department of Earth, Ocean and Atmospheric Sciences (EOAS) at the University of British Columbia, Dr. Marghaleray Amini, Research Associate and a Senior Lab Manager at PCIGR, and Vivian Lai (MSc), a Research Assistant at PCIGR, were among the international team of scientists who co-authored the study.

A scanning electron microscope image of a micrometeorite impact crater in a particle of material collected from asteroid Bennu. Credit: NASA Johnson Space Center

By studying Bennu’s elemental and isotopic makeup, the scientists traced its history back to a larger parent asteroid that broke apart after a collision, likely in the asteroid belt between Mars and Jupiter. That parent body formed over 4.5 billion years ago, during the birth of our solar system, from material with diverse origins—near the Sun, in the colder outer solar system, and even from other stars. “The variety of material that makes up Bennu is much greater than we could have imagined at the beginning,” said Dr. Weis. “There are even some pieces of Bennu that might predate the creation of our solar system. We have just a few grains, a few grams, that tell a very long history.”

Comparisons between Bennu, Ryugu (a similar asteroid sampled by the Japanese Hayabusa 2 mission), and Ivuna-type (CI) carbonaceous chondrite meteorites found on Earth suggest that their parent asteroids may have originated in the same region of the early solar system. However, Bennu stands out due to its higher levels of organic matter, anhydrous silicate minerals, and lighter isotopes of potassium and zinc. These differences suggest that the building blocks in that region either shifted over time or were not as evenly mixed as once thought. Remarkably, some of Bennu’s components appear to have survived heat, water, and even the violent collision that created the asteroid itself. “It's interesting on many levels because it reflects the original or older composition of the solar system, and it also allows us to understand how we arrived at the composition of the Earth that we have today,” said Dr. Weis.

Mass spectrometers at one of PCIGR’s analytical laboratories. Credit: D. Weis

PCIGR played a key role in these discoveries, analyzing the inorganic components of the Bennu samples for major and trace elements at extremely low concentrations. The team spent months optimizing sample handling methods and PCIGR’s highly sensitive, state-of-the-art mass spectrometers by analyzing reference meteorites of expected similar composition to Bennu. From the 121 grams of Bennu material that were returned to Earth in September 2023, Canada received 4% or almost 5 grams. PCIGR received enough material to carry out and repeat a series of analyses using the fine-tuned and thoroughly tested analytical protocols. The team carefully prepared and analyzed the elemental compositions of the Bennu samples, while ensuring they remained uncontaminated. 

“These analyses will help us to understand the origin and evolution not only of the parent body of this asteroid, but also of our entire solar system and other planetary bodies in time and space,” stated Dr. Amini. 

Another PCIGR-led publication on Bennu is in progress—stay tuned.

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