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 Science, doi:10.1111/maps.14227
NASA‘with OSIRIS-REx mission returned a sample from the asteroid Bennu and revealed that it contained key solar system materials and possible signs of a watery past. This discovery provides valuable insights into the conditions of the early solar system and the potential origin of life.
A deep dive into a sample of rock and dust returned from near-Earth asteroid Bennu by NASA’s University of Arizona-led OSIRIS-REx mission has revealed some long-awaited surprises.
Bennu contains the primordial components that formed our solar system, the OSIRIS-REx sample analysis team found. 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 prototype reentry capsule from NASA’s OSIRIS-REx mission is seen shortly after landing in the desert on Sept. 24, 2023, at the Department of Defense Test and Training Range in Utah. The sample was taken from asteroid Bennu in October 2020 by NASA’s OSIRIS-REx spacecraft. Credit: NASA/Keegan Barber
Travel and delivery of the Bennu sample
Launched on September 8, 2016, the Origins, Spectral Interpretation, Resource Identification and Security–Regolith Explorer spacecraft, called OSIRIS-REx, began its journey to the near-Earth asteroid Bennu to collect a sample of rocks and dust from the surface. OSIRIS-REx was the first US mission to collect a sample from an asteroid. The spacecraft delivered a sample weighing 4.3 ounces, or 121.6 grams, to Earth on September 24, 2023.
“Finally, after all these years, having the opportunity to dive into an OSIRIS-REx sample from Bennu is incredibly exciting,” said Dante Lauretta, OSIRIS-REx principal investigator and professor of planetary sciences at the University of Arizona Lunar and Planetary Laboratory. “This breakthrough not only answers long-standing questions about the early solar system, but also opens up new avenues of investigation into the formation of Earth as a habitable planet. The findings in our review sparked further curiosity and fueled our desire to explore further.”
Lauretta is a co-author of an article published in Meteoritics and Planetary Science which details the nature of the asteroid sample. The article also serves as an introduction to the Bennu Specimen Catalog, an online resource where specimen information is publicly available and where scientists can request specimen material for their own research.
“The publication of the first paper led by Dr. Lauretta and Dr. Connolly describing the Bennu sample is an exciting milestone for the mission and for the Lunar and Planetary Laboratory,” said Mark Marley, director of the Lunar and Planetary Laboratory at UArizona. Department of Planetary Sciences. “Our faculty, researchers and students will continue to study the specimen for years and decades. For now, we can only imagine the stories about the origin of our planet and life on it, which are still being told by grains of Bennu already in our laboratories.”
A top-down view of one of the containers containing rocks and dust from asteroid Bennu, with a hardware scale marked in centimeters. Credit: NASA/Erika Blumenfeld and Joseph Aebersold
A “watery past” for Benna?
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 between ocean water and materials from the earth’s mantle results in the formation of clay and gives rise to a range of minerals including carbonates, iron oxides and iron sulphides. But the most unexpected discovery in the Bennu sample is the presence of water-soluble phosphates, Lauretta said. These compounds are part of the biochemistry of all known life on Earth today.
A similar phosphate was found in a sample of asteroid Ryugu delivered by the Japan Aerospace Exploration Agency’s Hayabusa2 mission in 2020. However, the sodium magnesium phosphate detected in the Bennu sample stands out for its lack of inclusions, which are like small bubbles of other minerals trapped inside. rock and its grain size, unprecedented in any meteorite sample, Lauretta said.
The finding of sodium magnesium phosphates in the Bennu sample raises questions about the geochemical processes that brought these elements together 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,” Lauretta said. “Bennu may once have been part of a wetter world. However, this hypothesis requires further investigation.”
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
From a young solar system
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.
The composition of the asteroid offers a glimpse into the origins of our solar system more than 4.5 billion years ago. The rocks have preserved their original state, neither melted nor resolidified since their formation, which confirms their pristine nature and ancient origin.
This artist’s concept shows the OSIRIS-REx (Origins Spectral Interpretation Resource Identification Security – Regolith Explorer) spacecraft contacting asteroid Bennu using the Touch-And-Go Sample Arm Mechanism, or TAGSAM. The mission successfully returned a sample of Bennu’s surface coating to Earth for study. Credit: NASA
Tips on the building blocks of life
The team also confirmed that the asteroid is rich in carbon and nitrogen. These elements are key to understanding the environment from which Bennu’s materials originated 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 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.”
What will be next
Dozens of other 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 science papers describing the Bennu sample are expected from OSIRIS in the next few years. REx sample analysis team.
“The Bennu samples are tantalizingly beautiful alien rocks,” said paper co-author Harold Connolly, the mission’s sample scientist who leads the sample analysis team, a professor at Rowan University in Glassboro, New Jersey, and a visiting scientist at UArizona. . “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.”
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