The OSIRIS-REx Sample Analysis Team found that Bennu contains the primary components that formed our solar system. The dust from Bennu is rich in carbon, nitrogen, and organic compounds, essential for life. The sample also includes magnesium sodium phosphate, a finding that surprised researchers since it wasn't detected in the spacecraft's remote sensing data. This discovery suggests Bennu might have originated from a tiny, primitive ocean world.
Launched on September 8, 2016, the OSIRIS-REx spacecraft aimed to collect samples from Bennu's surface. This mission marked the first U.S. endeavor to collect asteroid samples, returning 121.6 grams of material to Earth on September 24, 2023.
"Finally having the opportunity to delve into the OSIRIS-REx sample from Bennu after all these years is incredibly exciting," said Dante Lauretta, principal investigator for OSIRIS-REx and Regents Professor of planetary sciences in the University of Arizona Lunar and Planetary Laboratory. "This breakthrough not only answers longstanding questions about the early solar system but also opens new avenues of inquiry into the formation of Earth as a habitable planet. The insights outlined in our overview paper have sparked further curiosity, driving our eagerness to explore deeper."
Lauretta co-authored a paper in Meteoritics and Planetary Science that details the Bennu sample's characteristics and introduces an online catalog where information about the sample is publicly available. Scientists can also request sample material for research through this resource.
"The publication of the first paper led by Dr. Lauretta and Dr. Connolly describing the Bennu sample is an exciting milepost for the mission and for the Lunar and Planetary Laboratory," said Mark Marley, director of the UArizona Lunar and Planetary Laboratory and head of the Department of Planetary Sciences. "Our faculty, scientists and students will continue to study the sample for years and decades to come. For now, we can only imagine the stories of the origins of our planet and the life upon it still to be told by the Bennu grains already in our laboratories."
Analysis of the Bennu sample has revealed it is dominated by clay minerals, particularly serpentine, similar to those found at mid-ocean ridges on Earth where mantle material encounters water. This interaction results in clay formation and produces various minerals, including carbonates, iron oxides, and iron sulfides. The most unexpected discovery in the Bennu sample is water-soluble phosphates, crucial to biochemistry for all known life on Earth today.
A similar phosphate was found in the Ryugu asteroid sample by Japan's Hayabusa2 mission in 2020. However, the magnesium sodium phosphate in the Bennu sample is unique due to its lack of inclusions and grain size, unprecedented in meteorite samples, according to Lauretta.
"The presence and state of phosphates, along with other elements and compounds on Bennu, suggest a watery past for the asteroid," Lauretta said. "Bennu potentially could have once been part of a wetter world. Although, this hypothesis requires further investigation."
Despite Bennu's possible watery history, it remains a chemically primitive asteroid, closely resembling the sun's elemental proportions. "The sample we returned is the largest reservoir of unaltered asteroid material on Earth right now," Lauretta said.
The asteroid's composition offers insights into the early solar system, over 4.5 billion years ago. The rocks have preserved their original state without melting or resolidifying, confirming their ancient origins.
The team also confirmed that Bennu is rich in carbon and nitrogen, crucial for understanding the chemical processes that transformed simple elements into complex molecules, potentially laying the groundwork for life on Earth.
"These findings underscore the importance of collecting and studying material from asteroids like Bennu - especially low-density material that would typically burn up upon entering Earth's atmosphere," said Lauretta. "This material holds the key to unraveling the intricate processes of solar system formation and the prebiotic chemistry that could have contributed to life emerging on Earth."
In the coming months, more laboratories worldwide will receive portions of the Bennu sample from NASA's Johnson Space Center in Houston. Numerous scientific papers from the OSIRIS-REx Sample Analysis Team are expected in the next few years.
"The Bennu samples are tantalizingly beautiful extraterrestrial rocks," said the paper's co-lead author, Harold Connolly, the mission sample scientist who leads the Sample Analysis Team, professor at Rowan University in Glassboro, New Jersey, and a visiting research scientist at UArizona. "Each week, analysis by the OSIRIS-REx Sample Analysis Team provides new and sometimes surprising findings that are helping place important constraints on the origin and evolution of Earthlike planets."
Related Links
OSIRIS-REx at LPL
Asteroid and Comet Mission News, Science and Technology
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