{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"15d28a791441b0561289b4be4e02e439dfcf8de3676698d1798b5cc4453b93d1","created":"2026-10-03T07:18:03Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"1f9a8705021922ba21ddb566fdf7fdc4c25becaf41a9e838442db1bb9d4ca5b5","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"earth.solar-system-dynamics.mercury-core","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"About 70 percent of Mercury's mass is in its metal core, far more than for Earth or Mars. It may have lost its rocky outer layers in a giant impact, or formed from material enriched in iron near the Sun.","posed_since":"","precise":"Explain Mercury's metal mass fraction (about 0.7) by mantle stripping in one or more hit-and-run or giant impacts, by chemical or magnetic sorting of iron-bearing solids in the inner disk, or by evaporation, consistent with MESSENGER's detection of a surface high in volatile elements (high K/Th, S, Na). An answer is a scenario matching bulk composition and volatile inventory.","problem_ref":null,"references":"","settled_by":"BepiColombo measurements of Mercury's interior and surface composition combined with formation models that predict both the metal fraction and the volatile abundances.","status_note":"BepiColombo is scheduled to enter Mercury orbit in late November 2026, with interior and surface-composition measurements to follow.","title":"Why does Mercury have such an outsized iron 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