NASA Logo, External Link
Facebook icon, External Link to NASA STI page on Facebook Twitter icon, External Link to NASA STI on Twitter YouTube icon, External Link to NASA STI Channel on YouTube RSS icon, External Link to New NASA STI RSS Feed AddThis share icon
 

Record Details

Record 1 of 1
Core Formation on Asteroid 4 Vesta: Iron Rain in a Silicate Magma Ocean
NTRS Full-Text: Click to View  [PDF Size: 81 KB]
Author and Affiliation:
Kiefer, Walter S.(Lunar and Planetary Inst., Houston, TX, United States);
Mittlefehldt, David W.(NASA Johnson Space Center, Houston, TX, United States)
Abstract: Geochemical observations of the eucrite and diogenite meteorites, together with observations made by NASA's Dawn spacecraft, suggest that Vesta resembles H chondrites in bulk chemical composition, possibly with about 25% of a CM-chondrite like composition added in. For this model, the core is 15% by mass (or 8 volume %) of the asteroid. The abundances of moderately siderophile elements (Ni, Co, Mo, W, and P) in eucrites require that essentially all of the metallic phase in Vesta segregated to form a core prior to eucrite solidification. Melting in the Fe-Ni-S system begins at a cotectic temperature of ~940 deg. C. Only about 40% of the total metal phase, or 3-4 volume % of Vesta, melts prior to the onset of silicate melting. Liquid iron in solid silicate initially forms isolated pockets of melt; connected melt channels, which are necessary if the metal is to segregate from the silicate, are only possible when the metal phase exceeds about 5 volume %. Thus, metal segregation to form a core does not occur prior to the onset of silicate melting.
Publication Date: Jul 23, 2017
Document ID:
20170005408
(Acquired Jun 16, 2017)
Subject Category: METALS AND METALLIC MATERIALS; LUNAR AND PLANETARY SCIENCE AND EXPLORATION
Report/Patent Number: JSC-CN-39689
Document Type: Conference Paper
Meeting Information: Annual Meeting of the Meteoritical Society (METSOC) 2017; 80th; 23-28 Jul. 2017; Sante Fe, NM; United States
Meeting Sponsor: Meteoritical Society; Piscataway, NJ, United States
Financial Sponsor: NASA Johnson Space Center; Houston, TX, United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: CHONDRITES; IRON; MELTING; METEORITIC COMPOSITION; SIDEROPHILE ELEMENTS; SILICATES; KAMACITE; TROILITE; LIQUID METALS; MAGMA; VESTA ASTEROID; ABUNDANCE; GRAIN BOUNDARIES; STOKES FLOW; CHEMICAL EQUILIBRIUM; VISCOSITY
› Back to Top
Find Similar Records
NASA Logo, External Link
NASA Official: Gerald Steeman
Site Curator: STI Program
Last Modified: June 16, 2017
Contact Us