“Mini psyches” give a glimpse of mysterious near-Earth asteroids rich in metals

Metal-rich near-Earth asteroids, or NEAs, are rare, but their presence offers the intriguing possibility that iron, nickel, and cobalt could one day be mined for use on Earth or in space.

New research, published in the Journal of Planetary Sciences, studied two metal-rich asteroids in our own cosmic backyard to learn more about their origins, compositions, and relationships with meteorites found on Earth.

These metal-rich NEAs were thought to have been created when the cores of developing planets were catastrophically destroyed early in the solar system’s history, but little more is known about them. A team of students co-led by University of Arizona Associate Professor of Planetary Sciences Vishnu Reddy studied asteroids 1986 DA and 2016 ED85 and found that their spectral signatures are quite similar to asteroid 16 Psyche, the largest metal-rich body in the solar system. Psyche, located in the main asteroid belt between the orbits of Mars and Jupiter rather than near Earth, is the target of NASA’s Psyche mission.

“Our analysis shows that both NEAs have surfaces with 85% metal like iron and nickel and 15% silicate, which is basically rock,” said lead author Juan Sanchez, based at the Planetary Science Institute. . “These asteroids are similar to certain stony iron meteorites such as mesosiderites found on Earth.”

Astronomers have speculated on the composition of Psyche’s surface for decades. By studying the metal-rich NEAs that come closer to Earth, they hope to identify specific meteorites that resemble the surface of Psyche.

“We started a compositional population survey of the NEA in 2005, when I was a graduate student, with the aim of identifying and characterizing rare NEA such as these metal-rich asteroids,” said Reddy, researcher. principal of the NASA grant that funded the work. “It is gratifying that we have discovered these ‘mini Psyches’ so close to Earth.”

“For perspective, a 50-meter (164-foot) metallic object similar to the two asteroids we studied created the Meteor Crater in Arizona,” said Adam Battle, co-author of the article with his colleague Lunar and Planetary Laboratory. graduate students Benjamin Sharkey and Theodore Kareta; and David Cantillo, undergraduate student in the Department of Geosciences.

The paper also explored the mining potential of 1986 DA and found that the amount of iron, nickel, and cobalt that could be present on the asteroid would exceed global reserves of these metals.

Additionally, when an asteroid is catastrophically destroyed, it produces what is called an asteroid family, a group of small asteroids that share similar orbital compositions and trajectories.

The team used the compositions and orbits of the 1986 DA and 2016 ED85 asteroids to identify four possible asteroid families in the outer region of the main asteroid belt, which houses the largest reservoir of small bodies in the inner part. of the solar system. It is also the region where most of the largest known metal asteroids reside, including 16 Psyche.

“We think these two ‘mini Psyches’ are probably fragments of a large metallic asteroid in the main belt, but not 16 Psyche itself,” Cantillo said. “It is possible that some of the iron and stony iron meteorites found on Earth may also have originated from this region of the solar system.”