This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The asteroid Bennu orbits the sun once every 1.2 years and approaches Earth every six years, passing within around 300,000 kilometers. NASA took advantage of this to collect material from the celestial body.
In a spectacular operation in 2023, the US space agency collected samples from the surface of the asteroid Bennu by its OSIRIS-REx probe. On Sept. 23, the sample container landed in the Utah desert, carrying around 120 grams of material from Bennu. From there, a small but precious portion made its way to ETH Zurich: Maria Schönbächler, professor of isotope geochemistry, received half a gram for analysis.
Her laboratory began analyzing the samples immediately. The investigations have now been completed, and the results have been published in Science Advances. They reveal the chemical fingerprint of Bennu's minerals and provide new insights into how our solar system formed.
The ETH researchers analyzed isotopes of iron, titanium and chromium. Isotopes are atoms of the same element that differ slightly in mass. Together, they create a distinctive fingerprint that researchers can use to determine the origin and, to some extent, the age of the asteroid.
The measurements show that titanium and iron are uniformly distributed throughout Bennu. They also reveal that Bennu has some close relatives: the asteroid Ryugu and the so-called CI meteorites, a class of primitive, carbon-rich rocky bodies found only very rarely on Earth. All three share a similar isotopic fingerprint, indicating that they formed from the same reservoir of cosmic dust.
They also differ significantly in isotopic composition from other known asteroids, meteorite groups and planets. Scientists had assumed that asteroids such as Bennu formed in the outer regions of the solar system, possibly where comets formed. They also thought Bennu formed relatively late in the solar system's evolution.
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