🔭 The enigmatic metal of asteroid Psyche under simulation

At the heart of the asteroid belt, a celestial object named Psyche deeply intrigues the scientific community. With its diameter of 226 kilometers (about 140 miles), its improbable metallic structure is an enigma: is it the exposed metallic core of an ancient protoplanet, or simply a chaotic aggregate of rock and metal, shaped by ancient collisions?

To unravel this enigma, scientists from the University of Arizona have conducted computer simulations focusing on a large crater located near the asteroid's north pole. Their work, published in the Journal of Geophysical Research: Planets, aims to predict what the NASA mission – whose arrival is expected in 2029 – might observe by analyzing the morphology of this depression. The team tested several internal architectures, comparing a scenario with a metallic core enveloped in rock to a structure where the materials would be uniformly mixed.


Porosity, that is, the amount of empty spaces inside the body, greatly influences crater formation. Upon impact, a porous material compresses more easily, absorbing the impact energy and generating deeper depressions, with less ejected debris. This parameter, often overlooked in models, could precisely allow to distinguish between a layered structure and a homogeneous composition. Researchers estimate that these characteristics will be clearly observable by the spacecraft's instruments.

Concretely, the simulations reconstructed the formation of a crater approximately 48 kilometers (about 30 miles) wide by 5 kilometers (about 3.1 miles) deep, using an impactor 5 kilometers (about 3.1 miles) in diameter striking at a typical speed of the main belt. The results obtained match the observed dimensions well, but without yet strictly distinguishing between the two composition hypotheses. However, integrating porosity into the calculations has refined predictions regarding the crater's shape and the distribution of ejecta.

The future Psyche mission will carry a series of instruments dedicated to studying the surface, gravity, magnetic field, and composition of the asteroid. The modeling provides valuable clues even now, such as internal density contrasts or the dispersion of metallic debris, which scientists can compare with observations. This collaboration between modelers and planetary scientists will allow a faster and more refined interpretation of the results once the spacecraft is in place.


Ultimately, elucidating Psyche's nature will shed light on planetary formation mechanisms in the early Solar System. If this asteroid proves to be an exposed planetary core, it would offer a unique view of the violent accretion phases, normally inaccessible on planets like Earth. In the other case, its mixed structure would inform about the intense collisions that shaped small bodies.

Impact simulations using hydrodynamics

To conduct this study, the researchers used advanced smoothed particle hydrodynamics computer codes. These tools virtually recreate collisions between asteroids by simulating the behavior of materials subjected to extreme forces. A 3D version of Psyche, built from telescope observation data, was thus "hit" by a virtual impactor of realistic size and speed for the main belt.

These models allow testing different hypotheses about the internal structure by varying parameters such as the impactor's size, collision angle, or target composition. They then generate precise predictions about the crater's morphology (width, depth) and the distribution of ejected materials. By adjusting these parameters, it becomes possible to identify which scenario best matches current observations, thus paving the way for the analysis of future mission data.