Formation of Asteroid (16) Psyche by a Giant Impact

Asteroid (16) Psyche is the largest likely metal‐rich asteroid in the Solar System and the target of the NASA Psyche mission. The mission aims to determine whether the asteroid is the core of a differentiated planetesimal that lost its mantle via a giant impact. To prepare for spacecraft observations of the asteroid, we combine impact and geodynamic models to predict the magnetization, composition, and interior structure of a mantle‐stripped core with the mass and density of Psyche. We show that Psyche‐like bodies can form from a single giant impact, with a hit‐and‐run collision being the most likely scenario. After the impact, Psyche's materials could have become magnetized while cooling in a dynamo field generated by its advecting core and/or in the magnetic field of the solar nebula. The former is diagnostic of Psyche being a mantle‐stripped core and is favored if Psyche's primordial sulfur content and current metal content are 10 wt.% and 50 wt.%, respectively. A sulfur content 10 wt.% delays core solidification long enough for kamacite in the asteroid's exterior to cool through the Curie temperature while the dynamo is still active. Formation of Psyche analogs with 50 wt.% metal content requires highly energetic impacts that more favorably occur after nebular‐gas dissipation. Therefore, if the Psyche spacecraft's Magnetometer, Gamma‐Ray Neutron Spectrometer, and Gravity and Topography Investigations respectively measure strong ( ) magnetization, sulfur‐rich surface provinces compatible with a bulk primordial sulfur content 10 wt.%, and metal content 50 wt.%, Psyche most likely formed as a mantle‐stripped core.