Asteroid samples collected from Bennu by NASA’s OSIRIS-REx mission have revealed fascinating details about the early solar system and the history of water in space.
These samples, the largest ever returned to Earth by an asteroid, provide scientists with invaluable data about the conditions and processes that existed billions of years ago.
The significance of Bennu and the OSIRIS-REx mission
Nine months after NASA’s OSIRIS-REx mission returned samples from asteroid Bennu, scientists are revealing surprising details about the asteroid’s past. Bennu was chosen for the mission because of its proximity to Earth, manageable size and presence of organic molecules.
These attributes make Bennu an ideal candidate for primary study materials of the solar system. Returning samples to Earth allows for more comprehensive analysis than can be done remotely. As Universe Today says, “returning samples to Earth is the best and most complete way to study asteroids.”
Bennu is a B-type asteroid, rich in carbonaceous materials that are critical to understanding the early solar system. These materials are essential for tracing the origin and formation of the solar system. Dante Lauretta, the chief researcher of OSIRIS-REx missionexplained the meaning: “Bennu could potentially have once been part of a wetter world.”
Analysis of Bennu samples
The samples, weighing around 120 grams, have been meticulously analyzed using various modern techniques, including plasma mass spectrometry, infrared spectrometry and X-ray computed tomography. The results reveal a complex composition of minerals and organic compounds, some of which are unexpected. The pristine nature of these samples means they have not undergone melting and resolidification, preserving their original state from billions of years ago.
One of the most intriguing findings is the presence of serpentine and other clay minerals, similar to those found along Earth’s mid-ocean ridges. These minerals suggest that Bennu may have had interactions with water in its past. Dante Lauretta highlighted the unexpected discovery: “The biggest surprise for me is that there are salt crusts covering some of the particles. We’re probably pretty familiar with it in Arizona. If you have hard water and you build up these white, hard salts that clog your shower head and faucets, it’s the same kind of process that we’re seeing with these asteroid samples. You had a salty liquid and it evaporated and left behind what we call evaporite minerals.
Findings and implications
The discovery of these minerals suggests that Bennu may have lived hydrothermal processes, similar to those on Earth’s ocean floor. This discovery is important because it suggests that water, a critical ingredient for life, may have been more common in the early solar system than previously thought. The presence of these clay minerals on Bennu parallels processes seen on Earth, providing a fascinating comparison and deeper understanding of planetary formation and evolution.
In addition, the presence of water soluble phosphates in the Bennu sample is particularly notable. These compounds are vital components of biochemistry and are found throughout the Earth’s biosphere. Their discovery on Bennu opens new avenues for understanding the distribution of life-sustaining chemicals in the Solar System. According to the study, published in Meteoritics and Planetary Science, “The presence and state of phosphates, along with other elements and compounds on Bennu, suggest a watery past for the asteroid.”
The study, conducted by Dante S. Lauretta and his team, provided a comprehensive overview of the sample that is now available for other researchers to request and study. “Finally having the opportunity to dig into the OSIRIS-REx sample from Bennu after all these years is incredibly exciting,” Lauretta said in a press release. “This breakthrough not only answers long-standing questions about the early solar system, but also opens new avenues for studying the formation of Earth as a habitable planet.”
