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El mapeo elemental realizado por Dawn revela H exogénico en el regolito de Vesta
Thomas H Prettyman1, David W Mittlefehldt, Naoyuki Yamashita
1Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA. prettyman@psi.edu
Science (New York, N.Y.)
|September 22, 2012
Resumen
Vesta Vesta es una de ellas.
Área de la Ciencia:
- Ciencias planetarias Ciencias planetarias.
- Ciencia de los asteroides Ciencia de los asteroides.
- La geoquímica es la geoquímica.
Sus antecedentes:
- Los meteoritos de howardita, eucrita y diogenita (HED) proporcionan información sobre la composición y evolución del asteroide Vesta.
- Estudios previos sugieren que los meteoritos HED se originan en Vesta.
- Comprender la diferenciación y la composición de la superficie de Vesta es crucial para la ciencia de los asteroides.
Objetivo del estudio:
- Para probar modelos de la evolución de Vesta utilizando datos del detector de rayos gamma y neutrones de la misión Dawn.
- Para investigar la distribución y el origen del hidrógeno en la superficie de Vesta.
- Para correlacionar la composición de la superficie con las características geológicas y el historial de impacto.
Principales métodos:
- Análisis de las proporciones globales de Fe/O y Fe/Si del detector de rayos gamma y neutrones de Dawn.
- Mediciones de neutrones para evaluar la composición y estructura de la corteza.
- Mapeando las concentraciones de hidrógeno a través de la superficie de Vesta.
Principales resultados:
- Las relaciones elementales globales confirman la consistencia con las composiciones de los meteoritos HED.
- Los datos de neutrones revelan una gruesa corteza inferior diogenítica expuesta en la cuenca de Rheasilvia, lo que apoya la diferenciación magmática.
- El hidrógeno sustancial está presente en el regolito de Vesta, con concentraciones más altas en las regiones ecuatoriales más antiguas y concentraciones más bajas en la cuenca de Rheasilvia.
Conclusiones:
- Vesta se sometió a una diferenciación magmática global, formando una corteza en capas.
- El hidrógeno probablemente se acumuló gradualmente a través de la caída de condrita carbonácea y fue modificado por impactos.
- Los hallazgos apoyan un modelo de la evolución de Vesta influenciado tanto por los procesos internos como por la entrega externa de materiales.
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