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Geological Sciences Seminar: Lindy Elkins-Tanton, Arizona State University, "Psyche: Journey to a Metal World "
When our solar system was just an infant, thousands of planetesimals formed in just a few million years. For many, heat from the decay of short-lived radioactive 26Al was trapped, causing cores to differentiate from the silicate mantle. Over the next few tens of millions of years, many planetesimals crossed paths catastrophically. Colliding worlds merged into even larger planets, eventually forming a small number of planetary embryos. Models show that among the accretionary collisions early in the solar system, some destructive “hit and run” impacts strip the silicate mantle from differentiated bodies. This is the leading hypothesis for Psyche’s formation: it is a bare planetesimal core. If our observations indicate that it is not a core, Psyche may instead be highly reduced, primordial metal-rich materials that accreted closer to the Sun.
The Psyche mission has been selected as the fourteenth in the NASA Discovery program. This mission will orbit the asteroid (16) Psyche to answer the following objectives:
- Determine whether Psyche is a core, or if it is unmelted material.
- Determine the relative ages of regions of its surface.
- Determine whether small metal bodies incorporate the same light elements as are expected in the Earth’s high-pressure core.
- Determine whether Psyche was formed under conditions more oxidizing or more reducing than Earth’s core.
- Characterize Psyche’s topography and impact crater morphology.
In this talk I will introduce what is known and what is hypothesized about Psyche, and discuss how we are progressing with this mission.