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Efectos químicos de grandes impactos en la atmósfera primitiva de la Tierra
B Fegley1, R G Prinn, H Hartman
1Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge 02139, USA.
Nature
|January 23, 1986
Resumen
Los impactos gigantes en la Tierra primitiva pueden haber creado moléculas clave para la vida. Esta investigación modela cómo los impactos de asteroides produjeron cianuro de hidrógeno (HCN) y formaldehído (H2CO), precursores vitales para la síntesis orgánica.
Área de la Ciencia:
- Astrobiología Astrobiología.
- Ciencias planetarias Ciencias planetarias.
- Química de la atmósfera La química de la atmósfera
Sus antecedentes:
- La Tierra primitiva experimentó un intenso bombardeo de asteroides y cometas.
- Este bombardeo puede haber alterado significativamente la atmósfera primitiva.
- Tales impactos podrían haber generado moléculas precursoras esenciales para la síntesis abiótica de compuestos orgánicos.
Objetivo del estudio:
- Para modelar la producción de cianuro de hidrógeno (HCN) y formaldehído (H2CO) en la atmósfera primitiva de la Tierra bajo condiciones de impacto.
- Evaluar la contribución potencial del HCN y H2CO generados por el impacto a la química prebiótica.
Principales métodos:
- Se utilizaron cálculos de equilibrio termoquímico y cálculos cinéticos químicos.
- Modelado paquetes de aire conmocionado a través de un rango de temperaturas, presiones y composiciones atmosféricas iniciales.
- Centrado en atmósferas con una relación carbono-oxígeno (C/O) mayor o igual a 1.
Principales resultados:
- Los impactos de bólidos pueden generar importantes proporciones de mezcla de volumen de HCN (10^-3 a 10^-5 en las regiones de impacto, 10^-5 a 10^-12 a nivel mundial) para C/O >= 1 atmósfera.
- Las proporciones de mezcla de H2CO en las regiones de impacto oscilan entre 10^-7 y 10^-9, con una distribución global limitada debido a la rápida eliminación atmosférica.
- La precipitación de HCN a los océanos podría suministrar (3-14) x 10 ^ 11 mol de HCN por año.
Conclusiones:
- Los impactos en la Tierra primitiva fueron una fuente plausible para el HCN prebiótico, potencialmente excediendo otras fuentes estimadas.
- El HCN generado podría haber jugado un papel crucial en la síntesis abiótica de moléculas orgánicas complejas.
- Si bien se produce H2CO, su corta vida atmosférica limita su contribución a la química prebiótica global.
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