NASA’s Psyche Mission: Journey to a Metal Asteroid

More than two centuries after asteroid 16 Psyche was first identified, scientists are still working to determine its origins. Located in the main asteroid belt between Mars and Jupiter, Psyche is the 10th-most massive asteroid and the largest known object made primarily of metal, measuring approximately 140 miles in diameter. NASA’s Psyche spacecraft is scheduled to arrive in 2029 to investigate its formation.

Unraveling Psyche’s Origins

Researchers hypothesize that Psyche could be a remnant of an early planet torn apart by massive collisions, or a fragment of a once-layered body that lost its outer rocky shell. Alternative theories suggest it may have formed as a metal-rich object from the beginning, or turn into a mix of rock and metal through repeated impacts. Each scenario offers a different perspective on how planets formed in the early Solar System.

Simulating Crater Formation to Understand Psyche’s Interior

To explore these possibilities, scientists at the University of Arizona’s Lunar and Planetary Laboratory created simulations to understand how a large crater near Psyche’s north pole may have formed. Their findings, published in JGR Planets, provide predictions that will help researchers interpret data collected by the Psyche mission. By combining these simulations with real observations, scientists hope to determine Psyche’s composition.

“Large impact basins or craters excavate deep into the asteroid, which gives clues about what its interior is made of,” said Namya Baijal, a doctoral candidate at the LPL and first author of the paper. “By simulating the formation of one of its largest craters, we were able to make testable predictions for Psyche’s overall composition when the spacecraft arrives.”

The Role of Porosity in Asteroid Impacts

The research highlighted the significant role of porosity – the amount of empty space within the asteroid – in crater formation. “One of our main findings was that the porosity plays a significant role in how these craters form,” said Baijal. “Porosity is often ignored because it’s difficult to include in models, but our simulations show it can strongly affect the impact process and shape of craters left behind.”

Asteroids with more internal voids absorb impact energy more effectively, resulting in deeper, steeper craters and less surface debris. Comparing simulated crater features with spacecraft observations will help scientists determine if Psyche has a layered interior or a chaotic mixture of materials.

Psyche as a Window into Planet Formation

The research team likened their approach to examining the remnants of an abandoned pizza shop. Psyche and other main belt asteroids are thought to be leftover building blocks from planet formation. “The cooks have long left, but you can look at what’s left behind – the ovens, scraps of dough, the toppings – and make inferences about how the pizzas were made,” said Erik Asphaug, a professor in LPL and co-author of the study. “We can’t get to the cores of Earth or Mars or Venus, but maybe we can get to the core of an early asteroid.”

If Psyche is indeed the exposed core of a former planet, it would provide unique insight into the violent phase of planetary evolution.

Modeling a Massive Impact

Researchers used detailed shape models based on telescope data to create a 3D representation of Psyche and recreate the formation of a crater roughly 30 miles wide and three miles deep. Simulations involved impacts at speeds typical for the asteroid belt, around three miles per second, testing different impactor sizes and comparing two internal structure models: a metallic core with a rocky mantle, and a uniform mixture of metal and silicate.

“We found that an impactor about three miles across would create a crater of the right dimensions,” Baijal said. “The crater’s formation is consistent with both scenarios of Psyche’s makeup.”

Including porosity in their simulations demonstrated its major influence on crater formation and debris distribution, as many asteroids contain fractured material and empty spaces from past collisions.

“By rigorously treating Psyche’s shape, porosity and composition, this perform represents a true watershed moment for our capacity to realistically simulate impacts into unique types of asteroids,” said Adeene Denton, a postdoctoral researcher and co-author of the study.

The Psyche Mission and Future Research

The Psyche spacecraft is equipped to measure the asteroid’s surface, gravity, magnetic field, and composition. The simulations predict features scientists can look for, such as density variations and the spread of metal-rich debris.

“When the spacecraft arrives at Psyche in a few years, the geochemists, geologists and modelers on the team will all be looking at the same object and trying to interpret what we see,” said Asphaug. “This work gives us a head start.”

The mission is led by Arizona State University, with Lindy Elkins-Tanton of the University of California, Berkeley, serving as principal investigator. NASA’s Jet Propulsion Laboratory manages mission operations, system engineering, and testing. The spacecraft was built by Maxar Technologies (now Intuitive Machines). Psyche is the 14th mission selected under NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center.