Researchers say the asteroid Bennu has a surprising watery past

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news of fascinating discoveries, scientific advances and more.

CNN
—

An early analysis of a sample collected from the asteroid Bennu suggests the space rock had an unexpectedly water-rich past, and may have been split off from an ancient ocean world.

NASA’s OSIRIS-REx mission collected the 4.3-ounce (121.6-gram) pristine sample from the near-Earth asteroid in 2020 and returned it to Earth last September.

Since then, scientists have been analyzing the asteroid’s rocks and dust to see what secrets they may hold about the asteroid’s composition and whether it could have delivered life to Earth. Asteroids are also of interest to scientists because they are remnants of the formation of the solar system.

An initial review of some samples, shared in October, indicated that the asteroid contains a significant amount of carbon.

In a new analysis of the sample, the team discovered that Bennu’s dust is rich in carbon, nitrogen, and organic compounds, all of which helped form the solar system. These ingredients are also essential for life as we understand it and could help scientists better understand how Earth-like planets evolved.

A detailed study of the findings appeared Wednesday in the journal Meteorites and planetary science.

“OSIRIS-REx has given us exactly what we were hoping for: a large sample of the parent asteroid, rich in nitrogen and carbon, from a formerly wet world,” said study co-author Jason Durkin, OSIRIS-REx project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The biggest surprise was finding sodium magnesium phosphate within the sample, which remote sensing had not initially detected when OSIRIS-REx, or the Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer mission, was orbiting Bennu.

Sodium magnesium phosphate is a compound that can be dissolved in water and is considered a component of the biochemistry of life.

It is possible that the asteroid broke away from… The researchers said that it is a small and primitive ocean world that no longer exists in our solar system.

The asteroid sample consists largely of clay minerals, including serpentine, making the sample remarkably similar to rocks found in mid-oceanic ridges on Earth. These ridges are where material from the mantle, the layer beneath the Earth’s surface crust, meets water.

Similar phosphate was found in a sample from the asteroid Ryugu collected by the Japan Aerospace Exploration Agency’s Hayabusa2 mission and returned to Earth in December 2020. But the compound from the Bennu sample is purer and contains larger grains.

“The presence and condition of phosphate, along with other elements and compounds on Bennu, suggests a watery past for the asteroid,” said study co-author Dante Lauretta, principal investigator of OSIRIS-REx and a professor at the University of Arizona. Towson, in a statement. “Bennu is likely part of a wetter world. Although this hypothesis requires further investigation.

The rocks collected from Bennu represent a time capsule from the early days of the solar system, dating back more than 4.5 billion years.

“The sample we brought back is the largest reservoir of unaltered asteroid material on Earth right now,” Loretta said.

Astronomers believe that space rocks such as asteroids and comets may have served as ancient messengers in our solar system.

“This means that asteroids like this may have played a key role in delivering water and other essential elements for life to Earth,” said Nick Timms, co-author of the study, a member of the OSIRIS-REx sample analysis team and an associate professor in the School of Earth and Planetary Science at Curtin University, in a statement.

If these smaller, rocky bodies were carrying water, minerals and other elements and collided with Earth as it formed billions of years ago, they could have helped set the stage for life to begin on our planet.

“These results underscore the importance of collecting and studying materials from asteroids like Bennu — especially low-density materials that typically burn up as they enter Earth’s atmosphere,” Lauretta said. “These materials hold the key to unraveling the complex processes of solar system formation and the biochemistry that may have contributed to the emergence of life on Earth.”

The wealth of material collected from the asteroid means that more laboratories around the world will receive their own pieces of the sample to study.

“Bennu’s samples are beautiful, exciting, extraterrestrial rocks,” said Harold Connolly Jr., the study’s principal investigator, OSIRIS-REx mission sampler and head of the geology department at Rowan University’s School of Earth and Environment in Glassboro, New Jersey. a permit. “Every week, analysis by the OSIRIS-REx Sample Analysis Team delivers new and sometimes surprising results that help place important constraints on the origin and evolution of Earth-like planets.”