Asteroid 16 Psyche Thought to Be Worth $10,000 Quadrillion Could Be a 'Rubble Pile'

An asteroid that scientists have previously estimated to be worth a staggering $10,000 quadrillion due to the potential value of its resources could be a "rubble pile," the lead author of a new study has said.

The paper, published in The Planetary Science Journal, indicates that the 140-mile-wide space rock, dubbed 16 Psyche, might not be as metallic or dense as previous research has suggested.

According to the study, which was led by University of Arizona (UA) undergraduate student David Cantillo, the findings suggest that the asteroid's formation may have played out differently to what scientists had previously thought.

It was long thought that the asteroid was the exposed iron core of a small planet that failed to form during the earliest days of the solar system, stripped of its mantle and crust.

But Cantillo and colleagues said that rather than being an exposed intact core of an early planet, 16 Psyche could actually be more similar to a "rubble pile," like the asteroid Bennu.

In astronomy, a "rubble pile" asteroid is one that is made up of many separate components that are weakly held together by their own gravity, rather than a single large piece of material, according to the Southwest Research Institute, based in San Antonio, Texas.

"Psyche as a rubble pile would be very unexpected, but our data continues to show low-density estimates despite its high metallic content," Cantillo said in a UA statement.

In the study, the researchers recreated 16 Psyche's regolith—the loose rocky material on its surface—by mixing together different materials in a lab. They then analyzed how light interacted with these materials until they matched telescope observations of the space rock.

These experiments revealed the potential breakdown of the materials that make up the asteroid. The researchers proposed that 16 Psyche is 82.5 percent metal, 7 percent low-iron pyroxene—a kind of mineral—and 10.5 percent carbonaceous chondrite material.

This latter material was likely delivered to the surface as a result of collisions with other asteroids, the researchers said.

"Having a lower metallic content than once thought means that the asteroid could have been exposed to collisions with asteroids containing the more common carbonaceous chondrites, which deposited a surface layer that we are observing," Cantillo said in the statement.

"This is the first paper to set some specific constraints on its surface content. Earlier estimates were a good start, but this refines those numbers a bit more."

Previous estimates of the asteroid's composition concluded that 16 Psyche could be made up of as much as 95 percent metal. Cantillo and colleagues also proposed that the asteroid is significantly less dense than previously thought.

16 Psyche was first spotted by an Italian astronomer in 1852—becoming only the 16th asteroid ever to be discovered.

In recent times, scientists have become interested in the space rock because it could provide a rare opportunity to study an exposed planetary core close up—if the traditional story of its origin is true. In fact, NASA is planning to a launch a mission to the asteroid in 2022, which is scheduled to reach 16 Psyche in 2026.

"The opportunity to study an exposed core of a planetesimal is extremely rare, which is why they're sending the spacecraft mission there, but our work shows that 16 Psyche is a lot more interesting than expected," Cantillo said in the statement.

Principal investigator for the NASA mission, Lindy Elkins-Tanton, previously estimated that the value of materials on Psyche, which is about the size of Massachusetts, could be around $10,000 quadrillion—that's $10,000 followed by 15 additional zeroes. This amount is greater than the worth of Earth's entire economy.

While NASA has no plans to mine the asteroid, Cantillo said that the latest findings could slightly bring down the estimated value of the asteroid.

Artist’s illustration of the asteroid 16 Psyche
An artist’s illustration of the asteroid 16 Psyche. Researchers have found in a study that the asteroid could actually be a rubble pile. iStock