2026-03-16 アリゾナ大学
An artist’s concept of asteroid 16 Psyche.Maxar/ASU/P.Rubin/NASA/JPL-Caltech
＜関連情報＞
- https://news.arizona.edu/news/large-craters-offer-clues-origin-asteroid-16-psyche
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025JE009231
盆地規模の衝突を通して（16）プシュケの内部構造を探る Exploring the Interior Structure of (16) Psyche Through Basin-Scale Collisions
Namya Baijal, Erik Asphaug, C. Adeene Denton, Martin Jutzi, Sabina Raducan, Saverio Cambioni, Linda T. Elkins-Tanton, Amanda Alexander
Journal of Geophysical Research: Planets Published: 13 March 2026
DOI:https://doi.org/10.1029/2025JE009231
Abstract
Asteroid (16) Psyche, the largest member of the M/X-type asteroids, may be the leftover core of a differentiated planetesimal. As such (16) Psyche will be explored in detail by NASA’s discovery-class Psyche mission in 2029. This will be the first mission to orbit a metal-rich asteroid, or any asteroid in the 100–500 km size range. A key unresolved question, and the primary objective of the mission, is to infer whether Psyche is a core or a primordial, unmelted object. One way to constrain an asteroid’s interior is through the study of its largest basins and how that affects its morphology, depth-to-diameter ratio, and surface distribution of metal. Here, in preparation for the mission, we model the impact formation of a significant basin at Psyche’s north pole, identified in ground-based imaging. Using high-resolution Smoothed Particle Hydrodynamics simulations applied to the asteroid’s 3D shape, we show how modeling the formation of Psyche’s impact basins will constrain its interior through comparison with mission observations and may allow us to infer whether Psyche has a core. We adopt two end-member interior structures: a differentiated target with a metal core and mantle, and a mixed rock-metal homogeneous target. We demonstrate the formation of the polar crater for both end-members, and how Psyche’s porosity and strength influence the depth-diameter ratio, the final crater morphology, and the expected simple-complex crater transition.
Plain Language Summary
Asteroid (16) Psyche, the largest (220 km diameter) of the class of objects suspected to be metal-rich, will be orbited by a NASA spacecraft in 2029–2030. It may be a large metallic core buried under rocks, a homogeneous mixture of iron and rock, or a primitive unmelted body. Here we study whether we can probe Psyche’s interior structure by studying the formation of its largest craters that may penetrate deep beneath the surface, making predictions based on models of their formation that can be tested by the spacecraft.
