16 Psyche: An asteroid once thought to be worth $700 quintillion

Space miners may have to dig somewhere else.
Chris Young
An artist's impression of 16 Psyche.NASA/JPL-Caltech/ASU

Future space missions will travel to asteroids to mine the great wealth of material they transport around space.

The "holy grail" of asteroids for future space miners is 16 Psyche, with early estimates suggesting it has a total net worth of $700 quintillion in heavy metals. NASA has already planned a mission to reach the space rock by 2026.

Now, according to a press statement, scientists revealed that 16 Psyche may contain fewer heavy metals than previously believed, dramatically lowering that estimated value.

16 Psyche was once thought to be worth $700 quintillion

16 Psyche is the largest-ever observed M-type asteroid, which is composed mainly of iron and nickel instead of the silicate rocks that make up the majority of other asteroids. The massive space rock, which orbits between Mars and Jupiter, measures around 140 miles (225 km) in diameter. In their paper, published in the Journal of Geophysical Research, the researchers from Purdue and Brown University detail how they made their new findings using advanced computer models. 

Due to seemingly contradictory readings, scientists have so far found it difficult to ascertain the exact composition of the giant space rock. The light that reflects off the asteroid suggests that it is indeed composed mostly of metal. However, measurements of the asteroid's gravitational interaction with nearby space objects suggest it is less dense than expected of a massive ball of iron hurtling through space.

Some researchers have suggested that, if Psyche is mainly composed of metal, it might be highly porous, meaning it would somewhat resemble a giant ball of steel wool with millions of tiny holes between filaments of heavy metal. "What we wanted to do with this study was see whether it was possible for an iron body the size of Psyche to maintain that near-50 percent porosity," explained Fiona Nichols-Fleming, a Ph.D. student at Brown and the study's lead author. "We found that it's very unlikely." 

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16 Psyche might be hiding a rocky mantle beneath a metal coating

In order to estimate the porosity of an object like 16 Psyche, Nichols-Fleming and a team of scientists from Brown and Purdue created a computer model based on the known thermal properties of metallic iron. The model showed that Psyche's internal temperature would have had to cool to below 800 Kelvin (980 °F/526 °C) very quickly after its formation to remain highly porous for an extended amount of time. If the temperatures had gone any higher, the iron would have been malleable enough that Psyche's own gravity would have collapsed most of that pore space, turning it into solid metal.

The researchers explained that it is incredibly unlikely that a space object the size of 16 Psyche would have cooled so quickly given the conditions of the early universe. Given their results, it is unlikely that 16 Psyche is a porous space rock made almost entirely of iron. They posited that the asteroid is likely hiding a rocky component that gives it a lower density than estimations based on light readings.

16 Psyche: An asteroid once thought to be worth $700 quintillion
An artist's impression of NASA's Psyche space probe. Source: NASA/JPL-Caltech

One theory the researchers explained is that 16 Psyche is a ferrovolcanic object. This means that volcanic activity on the asteroid might be bringing large amounts of its core to the surface, giving Psyche a metallic outer coating. 

Of course, none of this will be proven until NASA sends its Psyche probe to the space rock. The U.S. space agency aims to launch its spacecraft in August this year. After a four-year journey, it is expected to reach 16 Psyche around January of 2026. As Nichols-Fleming explains, Psyche is "such a bizarre and mysterious thing" that "anything [NASA's] mission finds will be really important new data points for the solar system."

If the Brown and Purdue University team's estimates are found to be true, 16 Psyche might be viewed by prospective miners as the asteroid equivalent of a fraudulent gold bar that's really cheap metal covered in gold coating. While the new research doesn't provide a new estimate on the number of heavy metals contained in 16 Psyche, it's likely that the $700 quintillion estimation will have to be marked down dramatically. Maybe scientists will start to set their sights more firmly on other alternatives, such as 1986 DA, which has an estimated value of $11.65 trillion.

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