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 will 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 (carbon, nitrogen, and organic compounds), the soil sample from the asteroid also contains magnesium and sodium phosphate. This element came as a surprise to the research team, as remote sensing data collected by the spacecraft on Bennu had previously given no 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 an 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 asteroid Bennu

The sample contained mostly clay minerals, particularly serpentine. This type of rock is found on Earth at mid-ocean ridges, where material from the Earth’s mantle meets water. This interaction creates 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 phosphates. These compounds are the biochemical components of all known life on Earth today.

Lauretta 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 peer into the early solar system more than 4.5 billion years ago. The asteroid material has been preserved in its original state, neither melting nor solidifying since its formation, a real treasure trove of research that is likely to generate more studies of Bennu in the years to come. (unpaid invoice)