The asteroid Psyche was previously assumed to be a large ball of pure iron, but recent study reveals it may include a buried rocky component.
According to a recent study by experts from Brown and Purdue universities, the asteroid 16 Psyche, which NASA plans to visit with a spaceship in 2026, may have less heavy metal and more hard rock than scientists previously assumed.
Psyche, the biggest of the M-type asteroids, circles the sun between Mars and Jupiter in the asteroid belt between Mars and Jupiter. M-type asteroids are formed mostly of iron and nickel, as opposed to the silicate rocks that make up most other asteroids. Psyche, however, offers conflicting indications concerning its makeup when observed from Earth.
Scientists can identify that the surface is primarily metal because of the light it reflects. As a result, it’s been suggested that Psyche might be the exposed iron core of a primordial planetary body, one whose rocky crust and mantle were blown away by an ancient collision. Measurements of Psyche’s mass and density, on the other hand, reveal a different scenario. Psyche’s gravity pushes on nearby bodies, indicating that it is significantly less dense than a massive piece of iron should be. If Psyche is entirely made of metal, it must be very porous, like a gigantic ball of steel wool with approximately equal parts empty space and solid metal.
“With this work, we wanted to investigate whether an iron body the size of Psyche could sustain that near-50 percent porosity,” Fiona Nichols-Fleming, a Ph.D. student at Brown and the study’s principal author, said. “We came to the conclusion that it’s very improbable.”
Nichols-Fleming collaborated on the research with Brown assistant professor Alex Evans and Purdue professors Brandon Johnson and Michael Sori, which was published in Geophysical Research Letters. The researchers developed a computer model based on known metallic iron thermal characteristics to predict how the porosity of a massive iron body would change over time.
According to the model, Psyche’s core temperature would have to drop below 800 Kelvin very quickly after creation in order for it to stay very porous. Iron would have been so bendable at such temperatures that Psyche’s own gravity would have compressed much of the pore space inside its mass. According to the researchers, a planet the size of Psyche — roughly 140 miles in diameter — could not have cooled that fast based on what is known about early solar system circumstances.
Furthermore, any event that may have contributed porosity to Psyche after its creation, such as a big collision, would have likely heated Psyche back up to above 800 K. As a result, any newly introduced porosity was unlikely to endure.
The findings, taken together, imply that Psyche isn’t a porous, all-iron body, according to the researchers. More than likely, it has a stony component that reduces its density. But, if Psyche has a rocky component, why does its surface seem to be so metallic from Earth? According to the experts, there are just a few probable reasons.
Ferrovolcanism, or iron-spewing volcanoes, is one of these possibilities. It’s plausible that Psyche is a distinct entity with a rocky mantle and an iron core, according to the researchers. However, massive ferrovolcanic activity may have pushed substantial portions of Psyche’s core to the surface, covering its rocky mantle with iron. Johnson and Evans’ previous research has proven that ferrovolcanism is conceivable on Psyche’s body.
Whatever the situation may be, astronomers will soon have a better understanding of this enigmatic asteroid. NASA intends to launch a spacecraft later this year that will collide with Psyche after a four-year voyage to the asteroid belt.
“The expedition is thrilling because Psyche is such a strange and fascinating creature,” said Nichols-Fleming. “As a result, anything the mission discovers will be very valuable new data for the solar system.”