A microscopic image of a dark Bennu particle, about a millimeter long, with a light phosphate crust. On the right is a smaller fragment that has broken off. Credit: From Lauretta & Connolly et al. (2024) Meteoritics and Planetary Sciencedoi:10.1111/maps.14227
Analysis of a sample from the asteroid Bennu has found the basic ingredients of life and hints of a watery past, offering insights into the origins of the solar system and prebiotic chemistry.
- An early analysis of the Bennu asteroid sample is back NASA‘with OSIRIS-REx the mission revealed dust rich in carbon, nitrogen and organic compounds, all of which are essential for life as we know it. The pattern, which is dominated by clay minerals, especially serpentine, reflects the type of rock found in mid-ocean ridges on Earth.
- The sodium magnesium phosphate found in the sample suggests that the asteroid may have separated from an ancient, small, primitive ocean world. The phosphate was a surprise to the team because the mineral was not detected by the OSIRIS-REx spacecraft while it was at Bennu.
- While a similar phosphate was found in a Ryugu asteroid sample provided by the company JAXAHayabusa2 mission (Japan Aerospace Exploration Agency) Hayabusa2 in 2020, the sodium magnesium phosphate detected in the Bennu sample stands out for its purity (that is, the lack of other materials contained in the mineral) and its grain size, unprecedented. in any meteorite sample.
This mosaic of Bennu was created using observations by NASA’s OSIRIS-REx spacecraft, which was in close proximity to the asteroid for more than two years. Credit: NASA/Goddard/University of Arizona
Discoveries of the composition of the asteroid Bennu
Scientists have been eagerly awaiting the opportunity to dig into a pristine 4.3-ounce (121.6-gram) sample of asteroid Bennu collected by NASA’s OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer) mission since it was delivered to Earth. last fall They hoped the material would hold secrets to the solar system’s past and the prebiotic chemistry that may have led to the emergence of life on Earth. An early analysis of the Bennu sample, published recently in Meteoritics and Planetary Scienceproves that this excitement was justified.
The team analyzing the OSIRIS-REx samples found that Bennu contains the original components that formed our solar system. Asteroid dust is rich in carbon and nitrogen as well as organic compounds, all of which are essential for life as we know it. The sample also contains magnesium sodium phosphate, which was a surprise to the research team because it was not seen in the remote sensing data collected by the Benn spacecraft. Its presence in the sample suggests that the asteroid may have separated from a long-extinct, tiny, primitive ocean world.
A view of the eight sample trays containing the final material from asteroid Bennu. Dust and rocks were poured into trays from the top plate of the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) head. 51.2 grams were removed from this casting, bringing the final asteroid sample weight to 121.6 grams. Credit: NASA/Erika Blumenfeld & Joseph Aebersold
Analysis of the Bennu sample revealed interesting insights into the composition of the asteroid. The pattern, which is dominated by clay minerals, especially serpentine, reflects the type of rock found in mid-ocean ridges on Earth, where material from the mantle, the layer below the Earth’s crust, meets water.
This interaction not only results in the formation of clay; it also gives rise to a number of minerals such as carbonates, iron oxides and iron sulphides. But the most unexpected discovery is the presence of water-soluble phosphates. These compounds are part of the biochemistry of all known life on Earth today.
While a similar phosphate was found in a sample of asteroid Ryugu delivered by JAXA’s (Japan Aerospace Exploration Agency) Hayabusa2 mission in 2020, the sodium magnesium phosphate detected in the Bennu sample stands out for its purity—that is, the lack of other materials in the sample. mineral—and its grain size, unprecedented in any meteorite sample.
A small fraction of a sample of the asteroid Bennu returned by NASA’s OSIRIS-REx mission, shown in microscope images. The upper left panel shows a dark Bennu particle, about a millimeter long, with an outer shell of light phosphate. The next three panels show zoomed-in views of a fragment of a particle that has split off along a bright phosphate-bearing vein captured by a scanning electron microscope. Credit: From Lauretta & Connolly et al. (2024) Meteoritics and Planetary Sciencedoi:10.1111/maps.14227
The finding of sodium magnesium phosphates in the Bennu sample raises questions about the geochemical processes that concentrated these elements and provides valuable clues about the historical conditions of Bennu.
“The presence and state of phosphates, along with other elements and compounds, on Bennu suggests a watery past for the asteroid,” said Dante Lauretta, co-author of the paper and OSIRIS-REx principal investigator at the University of Arizona. Tucson. “Bennu may once have been part of a wetter world. However, this hypothesis requires further investigation.”
“OSIRIS-REx has given us exactly what we hoped for: a large, pristine sample of a nitrogen- and carbon-rich asteroid from a formerly 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.
NASA’s OSIRIS-REx spacecraft leaving the surface of asteroid Bennu after collecting a sample. Credit: Goddard Space Flight Center/CI Lab/SVS NASA
Despite a possible history of interaction with water, Bennu remains a chemically primitive asteroid with elemental proportions very similar to those of the Sun.
“The sample we returned is the largest reservoir of unaltered asteroid material on Earth right now,” Lauretta said.
This composition offers a glimpse into the origins of our solar system more than 4.5 billion years ago. These rocks have preserved their original state, they have neither melted nor re-solidified since their formation, which confirms their ancient origin.
The team confirmed that the asteroid is rich in carbon and nitrogen. These elements are key to understanding the environment where Bennu’s materials formed and the chemical processes that transformed simple elements into complex molecules that potentially lay the foundations for life on Earth.
“These findings underscore the importance of collecting and studying material from asteroids like Bennu — especially the low-density material that would normally burn up upon entering Earth’s atmosphere,” Lauretta said. “This material is key to unraveling the complex processes of solar system formation and the prebiotic chemistry that may have contributed to life emerging on Earth.”
Dozens of other laboratories in the United States and around the world will receive portions of the Bennu sample from NASA’s Johnson Space Center in Houston in the coming months, and many more scientific papers describing Bennu sample analyzes are expected in the next few years. OSIRIS-REx Sample Analysis Team.
“The Bennu samples are tantalizingly beautiful alien rocks,” said Harold Connolly, co-author of the paper and OSIRIS-REx mission scientist at Rowan University in Glassboro, New Jersey. “Each week, analysis by the OSIRIS-REx sample analysis team provides new and sometimes surprising findings that help place important constraints on the origin and evolution of Earth-like planets.”
The OSIRIS-REx probe, which was launched on September 8, 2016, traveled to the near-Earth asteroid Bennu and collected a sample of rocks and dust from the surface. OSIRIS-REx, the first US mission to collect a sample from an asteroid, delivered the sample to Earth on September 24, 2023.
Reference: “Asteroid (101955) Bennu in the laboratory: Properties of a sample obtained by OSIRIS-REx” by Dante S. Lauretta, Harold C. Connolly, Joseph E. Aebersold, Conel M. O’D. Alexander, Ronald-L. Ballouz, Jessica J. Barnes, Helena C. Bates, Carina A. Bennett, Laurinne Blanche, Erika H. Blumenfeld, Simon J. Clemett, George D. Cody, Daniella N. DellaGiustina, Jason P. Dworkin, Scott A. Eckley, Dionysis I. Foustoukos, Ian A. Franchi, Daniel P. Glavin, Richard C. Greenwood, Pierre Haenecour, Victoria E. Hamilton, Dolores H. Hill, Takahiro Hiroi, Kana Ishimaru, Fred Jourdan, Hannah H. Kaplan, Lindsay P. Keller, Ashley J. King, Piers Koefoed, Melissa K. Kontogiannis, Loan Le, Robert J. Macke, Timothy J. McCoy, Ralph E. Milliken, Jens Najorka, Ann N. Nguyen, Maurizio Pajola, Anjani T. Polit, Kevin Righter, Heather L. Roper, Sara S. Russell, Andrew J. Ryan, Scott A. Sandford, Paul F. Schofield, Cody D. Schultz, Laura B. Seifert, Shogo Tachibana, Kathie L. Thomas-Keprta, Michelle S. Thompson, Valerie Tu, Filippo Tusberti, Kun Wang, Thomas J. Zega, CWV Wolner, and June 26, 2024, Meteoritics and Planetary Science.
DOI: 10.1111/maps.14227
NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provided overall mission control, 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 planning of the mission’s scientific observation 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. OSIRIS-REx is curated by NASA Johnson. International partnerships on this mission include CSA’s (Canadian Space Agency) OSIRIS-REx Laser Altimeter and the asteroid 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.