Sciences. Evidence for the origin of nearby asteroids rich in minerals

01-03-2022 Photograph of a stone meteorite called mesosiderite showing iron and nickel mixed with silicate rock. Arizona University of Research and Technology.

Madrid, 3 (Europe Press)

Near-infrared spectroscopy data from two material-rich NEAs (near terrestrial asteroids) have revealed new information about their composition and physical properties.

“We found that both new meteorites consist primarily of metal and a small portion of silicate minerals, similar to mesosiderites, a rare type of stony iron meteorite found on Earth,” explains Juan Sanchez, an associate research scientist, in a statement. Science Institute (PSI) and lead author of the paper, which was published in the Planetary Science Journal.

“Analysing their orbits allows them to trace their origin to a region in the outer asteroid belt where the largest metal-rich asteroids are located,” Sanchez said. The asteroid belt is located between the orbits of Mars and Jupiter.

“According to some studies, there are more than 60 archetypes represented among the iron meteorites found on Earth; however, these parental objects have not yet been identified. There are also iron stony meteorites and mineral-rich carbonaceous chondrites of unknown origin,” Sanchez said.

“Because NEAs represent a direct link between meteorites on Earth and their parent bodies throughout the Solar System, the identification of mineral-rich NEAs brings us closer to determining the exact origin of the meteorites from which they are derived.”

The largest NEA, (1986 DA), was shown to be essentially metal using radar data from a previous study. The mineral has a much higher radar reflectance than rocky objects made of silicate minerals. New near-infrared spectra from the DA team in 1986 confirmed that the asteroid’s surface is a mixture of about 85% metal and 15% pyroxene, a rock-forming silicate mineral found in igneous and metamorphic rocks.

For the other NEA, 2016 ED85, no radar data is available, but Sanchez found that the near-infrared spectrum is nearly identical to that of 1986 DA and other metal-rich asteroids, indicating that this object has a similar composition.

The paper’s findings are based on observations from NASA’s Infrared Telescope Facility on the island of Hawaii.

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