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Initial analysis of samples from the asteroid Bennu suggests that the space rock has an unexpectedly water-rich past, and may have broken up from an ancient ocean world.
NASA’s OSIRIS-REx mission will return a 4.3-ounce (121.6-gram) pure sample from the near-Earth asteroid in 2020. It returned to Earth last September..
Since then, scientists have been analyzing the rocks and dust from these asteroids to learn secrets about their composition and whether they could have provided the building blocks of life on Earth. Asteroids intrigue scientists because they are remnants of the formation of our solar system.
In some early reviews of samples shared in October, The asteroid contained a lot of carbon..
In a new analysis of the samples, the team found that Bennu’s dust is rich in carbon, nitrogen, and organic compounds, all of which were instrumental in the formation of our solar system. These ingredients are also essential for life as we understand it, and could help scientists better understand how planets like Earth evolve.
A study detailing the findings was published in the journal Neurology on Wednesday. Meteoritics and planetary science.
“OSIRIS-REx delivered exactly what we hoped for: a large, intact asteroid sample rich in nitrogen and carbon from a once-wet world,” Jason Dworkin, OSIRIS-REx project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and co-author of the study, said in a statement.
The biggest surprise was the discovery of sodium magnesium phosphate in the samples, which was not initially detected by remote sensing when the OSIRIS-REx (or Regolith Exploration Mission) orbited Bennu.
Sodium magnesium phosphate is a water-soluble compound that functions as a building block in the biochemistry of life.
Lauretta & Connolly et al. (2024)/Meteoritics and planetary science
Microscopic images show Bennu’s dark grains, roughly one millimeter long, surrounded by a bright phosphate shell.
Asteroids The researchers said the planet is a small, primitive ocean world that no longer exists in our solar system.
The asteroid sample is composed primarily of clay minerals, including serpentine, which bears a striking similarity to rocks found in Earth’s mid-ocean ridges, where material from the mantle, the layer beneath Earth’s crust, comes into contact with water.
Similar phosphates are Samples from the asteroid Ryugu A sample of Bennu was collected by the Japan Aerospace Exploration Agency’s Hayabusa 2 mission and returned to Earth in December 2020. However, the compounds in the Bennu sample are purer and have larger particles.
“The presence and state of phosphates on Bennu, as well as other elements and compounds, suggest that this asteroid was once rich in water,” co-lead study author Dante Lauretta, OSIRIS-REx principal investigator and Executive Professor at the University of Arizona, Tucson, said in a statement. “Bennu may have once been part of a wetter world, although this hypothesis requires further investigation.”
The rocks recovered from Bennu are a time capsule of the early solar system, more than 4.5 billion years ago.
Erica Blumenfeld/Joseph Aebersold/NASA
The OSIRIS-REx probe collected rocks and dust from the asteroid Bennu and returned them to Earth.
“The samples we brought back represent the largest repository of unaltered asteroid material currently on Earth,” Lauretta said.
Astronomers believe that space rocks such as asteroids and comets may have acted as ancient messengers in our solar system.
“This means that asteroids like this could have played an important role in delivering water and the building blocks of life to Earth,” Nick Timms, a member of the OSIRIS-REx sample analysis team, associate professor in Curtin University’s School of Earth and Planetary Sciences, and co-author of the study, said in a statement.
If these small rocky bodies, carrying water, minerals and other elements, collided with Earth billions of years ago when it was forming, they could have helped set the stage for life on Earth.
“These discoveries highlight the importance of collecting and studying material from asteroids like Bennu, especially the low-density material that would burn up upon entering Earth’s atmosphere,” Lauretta said. “This material holds keys to unlocking the complex processes of the formation of our solar system and pre-biotic chemistry that may have contributed to the emergence of life on Earth.”
Because of the sheer amount of material retrieved from the asteroid, more laboratories around the world will receive portions of the samples for study.
“The Bennu sample is a fascinatingly beautiful extraterrestrial rock,” co-lead study author Harold Connolly Jr., chair of the geology department at Rowan University’s School of Earth and Environmental Sciences in Glassboro, N.J., and sample scientist for the OSIRIS-REx mission, said in a statement. “Every week, analyses by the OSIRIS-REx sample analysis team yield new, sometimes surprising, discoveries that help place important constraints on the origin and evolution of Earth-like planets.”