A recent analysis of asteroid Bennu’s dust samples has unveiled crucial chemical building blocks associated with life.
The study, based on material collected by NASA’s OSIRIS-REx spacecraft, reveals a wealth of organic compounds and minerals in the asteroid’s dust, offering insights into the origins of life on Earth.
The samples, gathered from the 500-meter-wide asteroid, contain key molecules, including amino acids—the building blocks of proteins—and nucleobases, which are essential for the formation of DNA. While these findings do not indicate that life ever existed on Bennu, they support the hypothesis that asteroids, like Bennu, could have delivered vital ingredients for life to Earth billions of years ago, contributing to the conditions that enabled life to flourish.
In addition to amino acids and nucleobases, the samples also revealed an abundance of nitrogen, carbon-rich compounds, and various minerals. Some of these compounds had been observed in space rocks that have fallen to Earth, but others were new discoveries, shedding light on the potential for life to have arisen in diverse environments within our Solar System.
The study’s findings suggest that, like Earth, other planets in our Solar System could have received similar deliveries of water and organic materials from asteroids, increasing the possibility that life could exist elsewhere. The results also imply that Bennu, along with other asteroids, may have played a role in seeding early Earth with the ingredients necessary for life.
The research provides a deeper understanding of the early Solar System and the conditions that led to life on Earth.
“It enables us to answer these really, really big questions about where life began,” said Prof. Sara Russell, a cosmic mineralogist involved in the study. “Who doesn’t want to know about how life started?”
The OSIRIS-REx mission, launched in 2016, aimed to collect samples from Bennu using a robotic arm, which were then brought back to Earth in 2023. The samples, weighing around 120 grams, were distributed to scientists for analysis. Despite the seemingly small quantity, the material has proven to be an invaluable resource for understanding the asteroid’s chemical composition.
In addition to organic compounds, scientists found evidence of ammonia—an important chemical for biochemical processes—which was detected at levels much higher than those found in Earth’s natural soils. This discovery suggests that Bennu, or its precursor, once existed in a cold, outer region of space.
These findings contribute to the growing body of evidence that asteroids were instrumental in delivering organic material and water to Earth, potentially making life possible. The ongoing study of Bennu’s samples, along with future exploration of other asteroids and planets, continues to shape our understanding of life’s origins and the possibility of life beyond Earth.
While Bennu may not have supported life, its chemical composition provides crucial clues about the widespread distribution of life’s building blocks across the Solar System. The findings raise important questions for future research, particularly regarding why life emerged on Earth but not on other planets with similar ingredients.
The study was published in the journals Nature and Nature Astronomy on January 29, 2025.
