- Early analysis of the asteroid Bennu sample returned by NASA’s OSIRIS-REx mission has revealed dust rich in carbon, nitrogen and organic compounds, all of which are essential components for life as we know it. The sample is dominated by clay minerals, particularly serpentine, and reflects the type of rocks found on Earth at mid-ocean ridges.
- The magnesium sodium phosphate found in the sample indicates that the asteroid could have split off from an ancient, small, primitive ocean world. The phosphate was a surprise to the team because the mineral had not been detected in Bennu by the OSIRIS-REx spacecraft.
- Although a similar phosphate was found in the asteroid Ryugu sample delivered in 2020 by JAXA’s (Japan Aerospace Exploration Agency) Hayabusa2 mission, the magnesium-sodium phosphate detected in the Bennu sample is notable for its purity (i.e. , the lack of other materials included in the mineral) and the size of the grains, unprecedented in any meteorite sample.
Scientists have been eagerly awaiting the opportunity to dig into the pristine sample of the 121.6-gram asteroid Bennu collected by NASA’s OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer) mission since it launched on earth was delivered. last fall. They hoped the material would hold secrets about the solar system’s past and the prebiotic chemistry that might have led to the origins of life on Earth. An early analysis of the Bennu sample, published June 26 in Meteoritics & Planetary Science, shows that this excitement was justified.
The OSIRIS-REx Sample Analysis Team discovered that Bennu contains the original ingredients that formed our solar system. The asteroid’s dust is rich in carbon and nitrogen, as well as organic compounds, all of which are essential components for life as we know it. The sample also contained magnesium sodium phosphate, which was a surprise to the research team as it was not seen in the remote sensing data collected by the spacecraft at Bennu. Its presence in the sample indicates that the asteroid could have split off from a long-ago, small, primitive ocean world.
Analysis of the Bennu sample revealed intriguing insights into the asteroid’s composition. The sample is dominated by clay minerals, particularly serpentine, and reflects the type of rock found at Earth’s mid-ocean ridges, where material from the mantle, the layer beneath the Earth’s crust, encounters water.
This interaction not only results in clay formation; it also gives rise to a variety of minerals such as carbonates, iron oxides and iron sulfides. But the most unexpected discovery is the presence of water-soluble phosphates. These compounds are components of the biochemistry of all current life on Earth.
While a similar phosphate was found in the asteroid Ryugu sample delivered in 2020 by JAXA’s (Japan Aerospace Exploration Agency) Hayabusa2 mission, the magnesium-sodium phosphate detected in the Bennu sample is notable for its purity – which i.e. due to the absence of other materials in the sample. the mineral – and the size of the grains, unprecedented in any meteorite sample.
The discovery of magnesium-sodium phosphates in the Bennu sample raises questions about the geochemical processes that concentrated these elements and provides valuable clues about Bennu’s historical conditions.
“The presence and status of phosphates, along with other elements and compounds on Bennu, suggest a watery past for the asteroid,” said Dante Lauretta, co-lead author of the paper and principal investigator of OSIRIS-REx at the University of Arizona, Tucson. “Bennu could once have been part of a wetter world, although this hypothesis requires further investigation.”
“OSIRIS-REx gave us exactly what we hoped for: a large, pristine asteroid sample rich in nitrogen and carbon from a previously wet world,” said Jason Dworkin, co-author of the paper and OSIRIS-REx project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Despite its possible history of interacting with water, Bennu remains a chemically primitive asteroid, with elemental proportions very similar to those of the Sun.
“The sample we returned is currently the largest reservoir of unchanged asteroid material on Earth,” says Lauretta.
This composition offers a glimpse into the early days of our solar system, more than 4.5 billion years ago. These rocks have retained their original state, having not melted or re-solidified since their creation, confirming their ancient origins.
The team confirmed that the asteroid is rich in carbon and nitrogen. These elements are crucial for understanding the environments from which Bennu’s materials came and the chemical processes that transformed simple elements into complex molecules, potentially laying the foundation for life on Earth.
“These findings underscore the importance of collecting and studying material from asteroids like Bennu — especially low-density material that would normally burn up as it enters Earth’s atmosphere,” Lauretta says. “This material holds the key to unraveling the complicated processes of solar system formation and the prebiotic chemistry that could have contributed to the origins of life on Earth.”
Dozens of laboratories in the United States and around the world will receive parts of the Bennu sample from NASA’s Johnson Space Center in Houston in the coming months, and many more scientific papers are expected in the coming years that will further analyze the Bennu sample to describe. OSIRIS-REx sample analysis team.
“The Bennu samples are tantalizingly beautiful alien rocks,” said Harold Connolly, co-lead author of the paper and OSIRIS-REx mission sample scientist at Rowan University in Glassboro, New Jersey. “Each week, analysis by the OSIRIS-REx Sample Analysis Team yields new and sometimes surprising findings that help place important constraints on the origin and evolution of Earth-like planets.”
The OSIRIS-REx spacecraft, launched on Sept. 8, 2016, traveled to the near-Earth asteroid Bennu and collected a sample of rocks and dust from its surface. OSIRIS-REx, the first U.S. mission to collect a sample from an asteroid, returned the sample to Earth on Sept. 24, 2023.
NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provided overall mission management, systems engineering, and safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator. The university leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Littleton, Colorado, built the spacecraft and provided flight operations. Goddard and KinetX Aerospace were responsible for navigating the OSIRIS-REx spacecraft. Curation for OSIRIS-REx is at NASA Johnson. International partnerships for this mission include the Canadian Space Agency’s (CSA) OSIRIS-REx Laser Altimeter instrument and the asteroid sample science collaboration with JAXA’s Hayabusa2 mission. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.
Find more information about NASA’s OSIRIS-REx mission at:
https://www.nasa.gov/osiris-rex
By Mikayla Mace Kelley
University of Arizona, Tucson
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