Asteroid Bennu, a small space rock located approximately 200 million miles from Earth, serves as a time capsule revealing the materials that tell the story of its origin and transformation over billions of years. This ancient asteroid, which has been studied extensively through NASA’s OSIRIS-REx mission, has provided scientists with unique insights into the processes that shaped our solar system.
Bennu’s parent asteroid is believed to have formed more than 4 billion years ago. It was composed of materials from all different localities, including those close to the sun, far away, and yes, even materials from other stars. This intricate assembly of systems provides compelling genomic clues about the formation and evolution of our early solar system. The asteroid’s samples, now back on Earth, showcase how these materials have been altered by hydrothermal processes and interactions with water over billions of years.
Unique Geological Features of Asteroid Bennu
Studies have shown that nearly 80% of the minerals located inside space rock Asteroid Bennu harbor water hidden inside them. These unique water-bearing minerals were formed during the early years of our solar system. Water is golden. So why is water so important from an astrobiological perspective? Its existence invites profound new possibilities—like revealing the origins of all living organisms on Earth.
Bennu has survived millions of impacts with micrometeorites. These human-induced collisions have pockmarked the small world, creating microscopic craters and leaving little splashes of once-molten rock on its surface. Unique geological features on the asteroid arise from these impacts. In fact, the very severe space environment has continued to create features on its surface even today.
“In addition, we found organic material that’s highly anomalous in their isotopes and that was probably formed in interstellar space,” said Jessica Barnes, an associate professor at the University of Arizona‘s Lunar and Planetary Laboratory. “We have solids that formed closer to the sun, and for the first time, we show that all these materials are present in Bennu.”
The implications of these findings are profound. Samples collected from Bennu indicate that the starting materials in this region may have been altered over time. They propose that these materials weren’t mixed as uniformly as we once thought. This, in turn, challenges conventional understanding and highlights the need for additional research.
Research Contributions and Findings
NASA-Johnson Space Center’s Astromaterials Research and Exploration Science Division analyzed the sample returned from Bennu. Their work was instrumental in establishing the critical scientific baseline necessary for this prestigious environmental gold standard. That work has led to more than a dozen publications in leading journals, including Nature Astronomy and Nature Geoscience. The Kuiper-Arizona Laboratory for Astromaterials Analysis at the University of Arizona painstakingly analyzed the samples. This information helped to provide important context about the samples’ geological history.
Tom Zega, a researcher involved in the project, noted, “We think that Bennu’s parent asteroid accreted a lot of icy material from the outer solar system, which melted over time. Now you have a liquid in contact with a solid and heat—everything you need to start doing chemistry.” This highlights the ongoing dramatic processes that have occurred on Bennu. It further emphasizes Bennu’s ability to provide answers on how organic compounds may have originated and been delivered to Earth.
A significant aspect of the research is the recognition that weathering processes on Asteroid Bennu occur more rapidly than previously understood. This new realization really changes the game in terms of how we all thought to think about the effects time have on bodies like Bennu.”
The Importance of Sample Return Missions
Sample return missions like OSIRIS-REx are essential for improving our scientific understanding of asteroids like Bennu. By analyzing returned samples up close, scientists can learn things that aren’t possible to determine just with telescopic observations.
“It’s super exciting that we’re finally able to say these things about an asteroid that we’ve been dreaming of going to for so long and eventually brought back samples from,” Barnes expressed. Those in the scientific community are rightly disheartened by this sentiment. They understand how important these missions are to reveal the wonders of our solar system.
Bennu’s unique composition is all that remains of a record of planetary formation that took place over 4.5 billion years ago. This research is a treasure trove of exciting findings about Bennu. It reveals the past history of other worlds and the geological processes that influence their evolution.