Asteroid 16 Psyche, once thought to be a metallic core of an ancient planetesimal, may actually be a porous rubble pile, according to new research.
The findings, published in the journal Nature, could have implications for our understanding of how planets form and evolve.
"We thought we had a pretty good understanding of Psyche, but this new data suggests that we've been wrong all along," said lead author Dr. Jeffrey Venturini of the University of Arizona. "Psyche is a much more complex and mysterious object than we ever imagined."
Psyche is a 226-kilometer (140-mile) asteroid located in the asteroid belt between Mars and Jupiter. It is one of the largest asteroids in the belt and is the target of a NASA mission scheduled to launch in 2023.
The mission, called the Psyche mission, will send a spacecraft to orbit Psyche and study its composition and structure. Scientists believe that Psyche could be the exposed core of an early planet that was never able to fully form.
However, new data from NASA's Infrared Telescope Facility (IRTF) on Mauna Kea in Hawaii suggests that Psyche may not be as dense as scientists thought. The IRTF observations revealed that Psyche has a very low density, which is more consistent with a rubble pile than a solid metallic core.
"This is a really unexpected finding," said Venturini. "We were expecting Psyche to be very dense, like iron or nickel. But the IRTF data shows that it's actually very porous and lightweight."
The researchers believe that Psyche may have been formed by a collision between two smaller asteroids. The collision would have shattered the asteroids and created a rubble pile that is now held together by gravity.
"This is a really exciting finding," said Psyche mission scientist Dr. Lindy Elkins-Tanton of Arizona State University. "It means that the Psyche mission is going to be even more exciting and challenging than we thought. We can't wait to learn more about this enigmatic object."
The Psyche mission is scheduled to launch in 2023 and arrive at Psyche in 2026. The spacecraft will spend 21 months orbiting Psyche and will conduct a detailed study of its composition and structure.
