The Elusive Origin of Mercury

TL;DR

This paper reviews current hypotheses about Mercury's unique features, highlighting the challenges in understanding its origin due to gaps in knowledge about the early solar system and the incomplete nature of existing models.

Contribution

It provides a comprehensive review of proposed theories for Mercury's formation and discusses the limitations and gaps in current understanding.

Findings

Mercury's crust and mantle are more reduced than other solar system materials.

No single formation process explains all of Mercury's anomalies.

Existing models are incomplete and require further development.

Abstract

The MESSENGER mission sought to discover what physical processes determined Mercury's high metal to silicate ratio. Instead, the mission has discovered multiple anomalous characteristics about our innermost planet. The lack of FeO and the reduced oxidation state of Mercury's crust and mantle are more extreme than nearly all other known materials in the solar system. In contrast, moderately volatile elements are present in abundances comparable to the other terrestrial planets. No single process during Mercury's formation is able to explain all of these observations. Here, we review the current ideas for the origin of Mercury's unique features. Gaps in understanding the innermost regions of the solar nebula limit testing different hypotheses. Even so, all proposed models are incomplete and need further development in order to unravel Mercury's remaining secrets.