A nod to Benno's past

A sample of soil from the asteroid Bennu contains surprising traces that could point to a past that researchers have yet to suspect.

WASHINGTON, D.C. – In the fall of 2023, NASA’s Osiris-Rex spacecraft was able to safely return rock samples from the asteroid Bennu to Earth. For several months, the asteroid rock, which survived re-entering Earth’s atmosphere unscathed, was analyzed by a research team led by Dante Lauretta, principal investigator for NASA’s Osiris-Rex mission. The researchers made an unexpected discovery in the Bennu rock.

In addition to the basic “ingredients” of our solar system's composition (carbon, nitrogen and organic compounds), the soil sample from the asteroid also contains magnesium and sodium phosphate. This element was a surprise to the research team, as the remote sensing data collected by the spacecraft on Bennu had not previously given any indication of it. The research team interprets the presence of sodium and magnesium phosphate as evidence of the asteroid's origin.

Asteroid Bennu may have been part of the ocean world

Loretta explains in one: notice NASA: “The presence and condition of phosphate, as well as other elements and compounds, on Bennu suggests a watery past for the asteroid,” he added. “Bennu may have once been part of a wetter world. However, this hypothesis still needs further investigation.” The study’s findings In the specialized magazine Meteorites and planetary science published.

Jason Durkin, the mission’s project scientist and co-author of the study, is excited: “Osiris-Rex has given us exactly what we hoped for: a large sample of the parent asteroid, rich in nitrogen and carbon, and from a previously wet world.” Continued analysis of the asteroid samples is giving the research team more insights into the asteroid’s composition.

NASA's Osiris-Rex mission delivers rock samples from the asteroid Bennu

The sample contained mostly clay minerals, especially serpentine. This type of rock is found on Earth at mid-ocean ridges, where material from the Earth's mantle meets water. This reaction results in the formation of clay and a variety of minerals such as carbonates, iron oxides and iron sulfides. But the most notable discovery was the presence of water-soluble phosphate. These compounds are the biochemical components of all life known on Earth today.

Loretta is convinced: “The sample we brought back from Bennu is the largest reservoir of unaltered asteroid material currently on Earth.” The composition of the sample allows scientists to look back at the beginnings of the solar system more than 4.5 billion years ago. The asteroid's material has retained its original state and has not melted or solidified since its formation, which is a real treasure for research that is likely to produce more studies about Bennu in the coming years. (unpaid invoice)