Samples from the Bennu asteroid, brought back to Earth as part of NASA's OSIRIS-REx mission, have sparked excitement in the scientific world. New analyses reveal that Bennu contains not only material from the Solar System but also billions-of-years-old dust particles originating from other stars. Three new scientific papers, co-authored by Jessica Barnes from the University of Arizona, prove that Bennu's structure holds stellar remnants that existed before the formation of the Solar System.
The samples include:
Presolar (pre-solar) grains,
Organic compounds formed in interstellar space,
Solid particles shaped very close to the Sun,
Dust with abnormal isotopic compositions coming from distant regions.
These materials indicate that Bennu's parent body formed more than 4 billion years ago during the early stages of the Solar System's formation from particles originating from various sources.
The research also demonstrated hydrothermal alterations in Bennu's composition.
The asteroid's parent body was rich in ice from the outer Solar System. Over time, heat and impacts melted this ice, and the resulting water interacted with minerals, altering their compositions.
Traces of these water-rock interactions, which occurred billions of years ago, were found in 80% of the minerals analyzed in the samples.
A third study found that Bennu's surface changes rapidly due to micrometeorite impacts and solar wind.
About 20% of Bennu's particles showed signs of melting. This rate is much higher compared to samples from Ryugu (2%) and Itokawa (0.5%).
These findings suggest that space weathering occurs much faster on carbon-rich bodies.
Most meteorites that fall to Earth burn up in the atmosphere; those that do reach the surface quickly react with the atmosphere and lose their original structure.
Therefore, sample-return missions like OSIRIS-REx are considered critical for understanding the evolution of the Solar System and interstellar matter.
Scientists emphasize that with the samples from Bennu, we now have direct evidence of "stardust" older than the Solar System itself.
This is regarded as a historic step not only for understanding the asteroid but also for unraveling the origins of humanity.
